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• COP improvements of up to 16 % experimentally shown for high-glide mixtures compared to pure refrigerants. • COP of mixtures more robust against changes of operating conditions than pure fluids. Climate change necessitates the reduction of primary energy consumption. Industrial heat pumps can contribute by replacing oil and gas fired boilers in various applications. To cater the application, heat pumps must often impose temperature differences of 25 K or more to the heat source and heat sink, causing great irreversibility if evaporation and condensation occur at constant temperatures. Many theoretical studies suggest that high-glide refrigerant mixtures designed to match the temperature differences have a superior COP for such applications. In contrast to the numerous theoretical studies, systematic experimental studies are missing. This study tests high-glide mixtures at varying compositions at constant operating conditions. COP improvements of 16 % are shown comparing the best mixture against the best pure fluid. The improvement was established despite a significant degradation in the heat transfer coefficient, which could presumably be alleviated with larger heat exchangers. Additional parametric studies are conducted on the temperature differences of heat sink and source as well as the temperature level. The results show that mixtures not only outperform pure fluids at certain operating conditions but can maintain a higher COP across varying operating conditions. The binary and ternary mixtures in this study have glides between 10 and 40 K and consist of R1336mzz(Z), R1233zd(E), R1224yd(Z), R1234yf and R32. [ABSTRACT FROM AUTHOR]

In pharmaceutical freeze-drying processes, batch homogeneity is an important quality attribute. In this context, the edge-vial-effect is a challenging phenomenon. Shortly, this effect describes that vials at the edges of the shelf dry faster and at a higher temperature compared to vials in the middle of the shelf. Studies by Ehlers et al. revealed that this effect mainly origins from the number of neighbor vials cooling each other, which is reduced for vials in corners and edges compared to vials in the middle. Due to the reduced heat transfer in cyclic olefin polymer (COP) vials, the adverse edge-vial-effect should be greatly reduced allowing a better batch uniformity. In this focused study, glass and COP vials are compared regarding this effect on a fully loaded shelf. A reference experiment with vials placed at distance using a specially designed frame is presented as well. [ABSTRACT FROM AUTHOR]

• Energy, exergy, environment analyses and multi-objective optimization are performed for vortex tube coupled with transcritical refrigeration cycle (TVTC). • The parametric investigation is done to assess the thermodynamic performance of TVTC. • The cooling capacity of TVTC is found to be 10.1 % to 21.1 % higher than that of TVCR. • The maximum COP and exergetic efficiency of TVTC are higher than those of TVCR. • The evaporator temperature is the most influential input parameter in multi-objective optimization. The present study deals with the thermodynamic investigation of vortex tube coupled with trans-critical vapour compression refrigeration cycle (TVTC), followed by environmental analysis and multi-objective optimization. In this research, effect of various operating and design parameters is studied on the performance of TVTC. Furthermore, a comparison is made between the outcomes of TVTC and simple trans-critical vapour compression refrigeration cycle (TVCR). Results show that the optimum gascooler pressure for TVTC is observed to be lower than that of TVCR. Also, the cooling capacity and COP of TVTC are observed to be 10.1 % to 21.1 % and 2.3 % to 11.3 %, respectively, greater than those of TVCR. Moreover, the exergetic efficiency of TVTC is 2.3 % to 11.3 % higher than that of TVCR for the investigated range of evaporator and gascooler exit temperatures. The environmental penalty cost (per unit cooling capacity) of TVTC is 3.5 % to 12.2 % lower than that of TVCR. Furthermore, the coefficient of structural bond is calculated in order to choose the most sensitive parameters for system's performance. Additionally, genetic algorithm-based multi-objective optimization has been performed, with the evaporator temperature serving as the primary determining factor in establishing the optimal solution. This finding can guide the development of TVTC-based systems for a wide range of applications. [ABSTRACT FROM AUTHOR]

The investigation of cost-effective and highly efficient electrocatalysts for alkaline water and simulative seawater oxidation is essential to the conversion and storage of renewable energy. In this paper, the Ce–NiSe 2 /CoP catalyst with multihole and ultrathin nanosheet structure is generated. The unique structural characteristics of Ce–NiSe 2 /CoP heterojunction nanosheets contribute the excellent OER performance under different alkaline 1 M KOH and simulated seawater (1 M KOH + 0.5 M NaCl) electrolytes. Specifically, this catalyst exhucture is generated. The unique structural characteristics of Ce–NiSe 2 /CoP heterojunction nanosheets conibits the low overpotentials of 287 and 304 mV at the current density of 10 mA cm−2, along with the Tafel slopes of 87.1 and 78.8 mV dec−1 in two solutions, respectively. Moreover, the Ce–NiSe 2 /CoP target product also displays good stability. The present study introduces a promising strategy for the advancement of high-performance electrocatalysts in green energy field. [Display omitted] • The Ce-doped NiSe 2 /CoP heterostructure nanosheets are triumphantly generated. • The Ce–NiSe 2 /CoP product possesses multihole and ultrathin lamella architecture. • Each nanosheet with coarse surface is composed of prolifically nanosecondary units. • This catalyst presents fine OER properties in alkaline water and simulative seawater. [ABSTRACT FROM AUTHOR]

• Heat pump water heater with liquid-separation condensation is modelled and verified. • A 7.43 % improved COP and a 13.1 % shorter time with same condenser area is achieved. • A 22.22 % reduced condenser area and a 4.1 % shorter time with similar COP is obtained. • Optimized cases are superior at early stage of transient heating-up process. Heat pump water heater (HPWH) offers great potential to reduce energy consumption in water heating applications. But its performance enhancement and/or initial cost deduction are the main challenges to promote market penetration. In this paper, a heat transfer improvement technology, i.e., liquid-separation condensation (LSC), is implemented to HPWH and screen to achieve the maximized COP (E-HPWH) or reduced condenser area (R-HPWH). A model of HPWH with LSC is developed and validated, and its predictions are in good agreements with tested results from the baseline (B-HPWH) with an average deviation of 4.92 % at most. By using this validated model, E-HPWH and R-HPWH are obtained by adjusting the path arrangement and separation efficiencies. With the same heat transfer area, the COP of E-HPWH reaches 4.48, which is 7.43 % higher than that of B-HPWH, and the heating time is shortened by 13.1 %. With the same COP of B-HPWH being 4.17, the heat transfer area of R-HPWH is reduced by 22.2 % and heating time is shortened by 4.1 %. Then transient heating-up process of three HPWHs are comparatively investigated. Results indicate that E-HPWH has the highest compressor power as well as pressures and temperatures at the inlets of condenser and evaporator, followed by R-HPWH and B-HPWH. E-HPWH and R-HPWH overperform B-HPWH in terms of heat capacity before 4220s, due to the increased mass flowrate. Compared to B-HPWH, E-HPWH and R-HPWH have averagely 15.02 % and 7.29 % higher COP before 2790s and 1860s, respectively. Their states are less differentiated as the water temperature increases. [ABSTRACT FROM AUTHOR]

• Detailed energy and exergy analyses are conducted on the proposed ARC. • Explore the effects of varying refrigerant mass flow rate and ammonia concentration in strong and weak solutions on key performance parameters. • Employing the GBRT machine learning method and FHO approach in the ARC is highly recommended. • The GBRT model proves to be a reliable predictive tool with strong accuracy, offering valuable insights into system performance. • The generator is the main source of exergy destruction rate (50 %). A detailed analysis of energy and exergy is conducted on a single-effect solar ammonia–water (NH 3 –H 2 O) absorption refrigeration cycle (ARC) using TRNSYS and EES software. Considering the physical and chemical exergies, the exergy destruction rate (Ė D) in each component of the system is calculated, highlighting its contribution to the overall Ė D. The study explores the effects of varying refrigerant mass flow rate (ṁ ᵣ) and ammonia concentration in strong and weak solutions (X s and X w) on key performance parameters, including coefficient of performance (COP), exergy efficiency (Ė D), and overall Ė D across a range of generator temperatures (T g). In this study, a gradient boosting regression tree (GBRT) is employed as a supervised machine-learning technique for classification and regression problems, utilizing boosting to enhance conventional decision tree predictions. The Fire Hawk Optimizer (FHO) approach is also utilized to optimize performance parameters, maximizing COP and η η E while minimizing T g and Ė D. The GBRT models are developed using available experimental and simulation data, revealing relationships between variables (ṁ ᵣ, X s , X w , and T g) and outcomes (COP, Ė D , and overall Ė D). The results revealed that the generator exhibits considerable Ė D regardless of operating conditions, underscoring its pivotal role in the ARC. It emerges as the primary Ė D contributor (50 %), followed by the evaporator (17 %) and the absorber (15 %). However, Ė D associated with the recooler, pump, and expansion valves is negligible in comparison. Optimization results reveal that, when minimizing T g and Ė D , the highest COP and Ė D at T g of 373.15 K reach 0.8081 and 0.46, respectively. [ABSTRACT FROM AUTHOR]

In this study, we meticulously prepared electrocatalysts in the form of Ru nanoclusters-decorated CoP nanowire arrays supported on carbon cloth (Ru@CoP/CC) for HER under both alkaline and acidic conditions. Ru@CoP/CC exhibited exceptional catalytic activity for hydrogen evolution, showcasing overpotentials of 48 mV and 66 mV (10 mA/cm2) in acidic and alkaline media, respectively, which closes to 20% of commercial Pt/C catalysts. Moreover, they showcased outstanding durability, a crucial aspect for their practical application in hydrogen production. Furthermore, this research employed DFT computations to attain a comprehensive understanding of the electronic and structural modifications brought about by the integration of Ru nanoclusters. Ru nanoclusters could coordination environment of CoP, and then effectively accelerate the catalytic reaction. This method opens up a new way to reduce the amount of precious metals in the electrocatalyst, and is helpful to the development of high-performance HER electrocatalyst. • Ru@CoP/CC electrocatalyst is prepared by hydrothermal and phosphorization process. • Ru nanoclusters alter the local electron distribution around the CoP. • The coupling effect of Ru and CoP enhances the performance of HER. • Ru@CoP/CC electrocatalyst presents excellent acidic and alkaline HER performance. [ABSTRACT FROM AUTHOR]

• Velocity characteristics at the injection pipe outlet is affected by the pressure wave in injection pipe. • There is a backflow at the injection pipe outlet. • The amount of backflow varies against the injection pipe length and decrease under resonant condition. • A backflow may cause a heat loss by heating liquid refrigerants from the flash tank. • Reducing a backflow using the resonance is advantageous for improving the COP of vapor injection cycle. The vapor injection cycle with flash tank and two stage compressor is known as an efficient cycle. It is known that the intermediate pressure is a key factor for COP improvement and pressure change during the injection process could reduce the COP. However, the effect of the pulsating intermediate pressure of a two-stage compressor on COP is not clear. In a previous study, the authors experimentally showed that COP varied with injection pipe length. There seemed to be a correlation between COP and the resonance phenomenon caused by pressure pulsation in the injection pipe. However, the mechanism of COP improvement is not well understood. In this study, a one-dimensional simulation model was developed to clarify the mechanism and was verified with the experimental results. The simulation results show that resonance in the injection pipe does not increase the injection mass flow rate into the suction pipe. On the contrary, backflow occurs in the injection pipe and the backflow ratio is minimum in the resonant condition. Due to the high temperature of the backflow coming from the discharge pipe, the saturated vapor from the flash tank is easily heated, causing heat loss and lower COP. It was found that COP can be improved by using resonance to suppress the backflow. [ABSTRACT FROM AUTHOR]

• A direct evaporative cooler (DEC) integrates with split air conditioner (SAC). • DECSAC significantly improves C O P by 10.54 %−70.14 %. • Total cost rate (T C R) of DECSAC reduces by 5.07 %−25.36 %. • Water consumption for 1 kWh energy saving varies between 5.5 – 9.8 L. • Simple payback period lies between 1.21 to 2.99 years with maximum I R R being 59 %. As concerns regarding energy consumption and environmental impact continue to grow, the need for efficient and sustainable cooling technologies becomes increasingly significant. Among various alternatives, direct evaporative cooling (DEC) has emerged as a promising solution due to its energy-efficient operation and low environmental footprint. This paper aims to provide a comprehensive thermo-economic assessment of a 5.25 kW capacity split air conditioner (SAC) integrated with direct evaporative cooling, focusing on evaluating its performance, energy consumption, coefficient of performance (C O P) , and economic viability. A numerical model is developed to determine the reduction in the condenser inlet air temperature due to direct evaporative cooling. The ambient temperature (30–45 ⁰C), relative humidity (20–80 %), and evaporator temperature (3–12 ⁰C) are taken as the design variables. Box–Behnken design (BBD) technique of response surface methodology is applied for multi-objective optimization. The C O P , total cost rate (T C R) , and total exergy destruction ( E ˙ D , t ) are set as the objective functions. Cooling capacity, life period, operation time, interest rate, maintenance factor, and electricity cost are taken as constants. The thermoeconomic optimization evolved maximized C O P enhancement of 68.94 %, and reduction in TCR and E D , t by 26.12 % and 57.23 %, respectively. The water consumption to energy saving ratio varies from 5.5 to 9.8 L/kWh for different months of the cooling season. The thermoeconomic performance and sustainability of DECSAC is observed to significantly improve compared to conventional SAC specifically in hot-dry climates. The simple payback of the proposed system ranges between 1.21 to 2.99 years depending upon the operating conditions. [ABSTRACT FROM AUTHOR]

• A vapor-liquid adjustment evaporator is pioneered to heat pump water heater. • Serials experiments are conducted for performance comparisons. • Current vapor-liquid adjustment evaporator cannot ensure its superiority for each period. • A 6.35 % higher COP and 16.18 %−63.37 % lower evaporator pressure drops are found. Adjusting vapor and liquid in the evaporator could lead to heat transfer enhancement and pressure drop reduction simultaneously. Its benefits in the steady system, such as air conditioning and heat pump, have been confirmed extensively, but its effectiveness in the dynamic system is not explored yet. In this paper, a vapor-liquid adjustment evaporator is implemented to heat pump water heater (HPWH-AE) featured by a dynamic water heating process. Comprehensive comparisons to the heat pump water heater with a conventional evaporator (HPWH CE) are experimentally investigated and discussed. Firstly, the matching test reveals that the optimized HPWH-AE has a 6.35 % higher COP than HPWH CE. Secondly, the detailed comparisons indicate that HPWH-AE has less evaporator pressure drop, smaller compressor ratio, higher refrigerant mass flowrate and decreased power consumption than HPWH CE. Thirdly, the divided tests are carried out with an increment of half hour. The results suggest that HPWH-AE outperforms HPWH CE in terms of heating capacity and COP at the first one and half hours, which becomes inferior afterwards. However, HPWH-AE has always lower power consumption relative to HPWH CE. The images from FLIR camera show that the vapor-liquid adjustment evaporator is featured by effectively utilizing heat transfer area, resulting from more evenly distributed temperatures. Finally, the feasibility is examined at various operating conditions. HPWH-AE could have higher heating capacity and lower power consumption than HPWH CE simultaneously when ambient temperature is between 18 °C and 26.5 °C. HPWH-AE always has higher COP of 4.92–6.35 % than HPWH CE. [ABSTRACT FROM AUTHOR]

It is of great significance to develop economical, stable and abundant non-precious metal OER catalysts to replace the precious metal for the application and generalization of electrocatalytic overall water splitting technology. Herein, advanced Ni-doped CoP encapsulated by B, N co-doped carbon (Ni–CoP/BNC) electrocatalysts were prepared by using simple hydrothermal synthesis and calcination. The optimized Ni–CoP/BNC showed exhibits OER electrocatalytic performance with only need 247 mV to achieve 10 mA cm−2, outperforming the commercial RuO 2. Combining various characterizations and DFT calculations, the excellent electrocatalytic performance mainly comes from three aspects: (1) Ni doped into CoP can significantly regulate the electronic structure of Co3+, and B doped into carbon layer can slightly regulate the electronic structure of Co3+, so that the electronic structure of Co3+ can be accurately regulated, resulting in the optimal OOH* adsorption energy; (2) Ni and B can be favor in oxidizing Co0 to Co3+, which is beneficial to persistently provide a catalytic active center for oxygen evolution reaction; (3) the B, N codoped carbon layer can effectively reduce the damage of strong alkali solution to the catalytic active center as armor. This work opens up fresh opportunities in the accurate regulation of electronic structure by surface and interface double doping for efficient oxygen evolution in water applications. • Ni, B stepwise regulate the electronic structure of Co to reduce the adsorption energy of RDS. • Ni, B are favor in oxidizing Co0 to Co3+, which is benefical to persistenly provide catalytic active center for OER. • B, N-doped carbon can effectively reduce the damage of strong alkali solution to the catalytic active center. [ABSTRACT FROM AUTHOR]

Aqueous zinc-air batteries provide a possibility to replace fossil fuels. However, developing bi-functional electrocatalysts with high activity, low-cost and environmental friendliness for zinc-air batteries remains a challenge. In this work, we report an efficient bifunctional electrocatalyst (H–CoP@NC) that is fabricated by phosphating a hollow metal organic framework (MOF) prepared using a self-template method. The H–CoP@NC exhibits a half-wave potential of 0.81V (vs. RHE) for the oxygen reduction reaction (ORR), and an overpotential of 390 mV for the oxygen evolution reaction (OER) at a current density of 10 mA cm−2. Remarkably, the H–CoP@NC assembled zinc-air battery possesses a voltage gap of 0.82 V at a current density of 50 mA cm−2, and the voltage gap increases by only 0.01 V after 730 continuous charge and discharge cycles. This excellent electrocatalytic activity for ORR and OER can be attributed to the hollow structure, which improves mass transport during the electrocatalytic reaction, and the synergistic effect between CoP and heteroatom doped carbon skeletons which provide a high density of exposed active sites. • H–CoP@NC is prepared by phosphating hollow Co-based metal organic framework. • H–CoP@NC exhibits an excellent ORR activity with a half-wave potential of 0.81 V vs. RHE. • H–CoP@NC assembled battery possesses a good rechargeability, stability and battery efficiency. • The synergy effect of CoP and N–C skeletons contributes to the superior activity of ORR and OER. [ABSTRACT FROM AUTHOR]

Designing highly-efficient, stable and low-cost catalysts for electrocatalytic hydrogen evolution reaction (HER) plays an important role in renewable energy conversion technology. The particularly ultrathin and porous 2D architecture can provide plentiful activation sites, short delivery channels to improve reaction kinetic and promote HER procedure. High-performance transition metal phosphide (CoP) combined with unique and holey 2D ultrathin nanosheet structure is prepared by successively hydrothermal reaction, oxidation and phosphorization techniques, which presents remarkable stability and electrocatalytic HER properties in a wide pH range. The thickness and pore dimension of ultrathin and porous CoP nanosheets are ∼15 and 3–17 nm. The optimized CoP nanosheets only require 60, 128, 90 mV overpotentials to drive the current density of 10 mA cm−2 in acidic, neutral and alkaline environment, respectively, much better than those of oxide counterpart and the previously reported transition metal-based electrocatalysts. Moreover, the small Tafel slopes of porous CoP nanosheets are 54, 69.9 and 62.9 mV dec−1 in acidic, neutral and alkaline media. CoP nanosheets also exhibit high conductivity, large C dl , and long-term stability for 20 h in pH-universal electrolyte. • The unique and neoteric CoP nanosheets were successfully synthesized. • The CoP nanosheets possess ultrathin and porous architecture. • The thickness and pore dimension of ultrathin CoP nanosheets are ∼15 and 3–17 nm. • The optimized CoP nanosheets displayed outstanding HER activity in a wide pH range. [ABSTRACT FROM AUTHOR]

This paper presents a comparison of the thermodynamic performances of magnetocaloric and vapor compression cooling technologies when operating the same wine cooler cabinet. The vapor compression system used is a commercially available 31-bottle domestic wine cooler, while the magnetocaloric cooling device is a state-of-the-art (TRL-5) prototype connected to the retrofitted wine cooler cabinet. The test procedures involved characterizing the unsteady and steady-state behavior of both technologies. Detailed instrumentation of both systems allowed for a unique low-level performance comparison, considering first- and second-law-based parameters, which has not been explored in the literature. Overall, the wine cooler was found to be more efficient when operated by the vapor compression system. For an ambient temperature of 25 °C and a cabinet temperature of approximately 12 °C, the coefficient of performance (COP) and second-law efficiency of the wine cooler were 0.7 and 3.6% respectively when using the vapor compression system, whereas they were 0.49 and 2.0% respectively when using the magnetocaloric refrigerator system. However, despite the contrast between the internally ideal coefficient of performance of the magnetocaloric wine cooler and the vapor compression wine cooler, significant but realistic design improvements were suggested. These suggestions were evaluated and quantified using a system-level magnetocaloric refrigerator model. The numerical results indicate that with changes in the current pumping system and magnetocaloric materials, an improved version of the magnetocaloric wine cooler could surpass the COP of its original version by 88% and the vapor compression system by 31%. • Magnetic (MR) and vapor compression (VC) coolers are compared on the same basis. • The MR device is a TRL-5 prototype connected to a retrofitted wine cooler cabinet. • For a 12 °C/25 °C span, the VC and MR systems' COPs were 0.7 and 0.49, respectively. • Design improvements were suggested for the MR system using a validated model. • An improved MR cooler could surpass the COP of its original version by 88%. [ABSTRACT FROM AUTHOR]

• Employing motor-driven turboexpander compressor provides cooling below −60 °C. • System performance under variable rotating speeds and refrigeration conditions. • Operating characteristics of motor-driven turboexpander compressor are explored. • Advanced exergy analysis shows great potential for the refrigerator improvement. Turbo-refrigerator based on reverse Brayton cycle is an attractive solution for providing refrigeration at ultra-low temperatures below −60 °C for deep freezing. Employing a motor-driven turboexpander compressor (MTEC) not only allows the turbo-refrigerator to achieve high compactness, reliability and flexibility, but also leads to new operating characteristics especially in a closed cycle. This paper aims to investigate the operating characteristics of a closed-cycle single-stage turbo-refrigerator with a MTEC. A high-speed turbo-refrigerator system with the design refrigeration temperature of −86 °C was manufactured and then tested under variable rotating speeds and refrigeration conditions. Test results show that a refrigeration temperature below −96.4 °C was obtained in a pull-down progress. Compared with a fixed-speed operation, variable-speed operation enables the independent control of the refrigeration temperature and the cooling capacity. With the decrease in the refrigeration temperature (or in the cooling capacity), the rotating speed has a greater effect on the COP than that on the cooling capacity (or on the refrigeration temperature). The mass flow rate along with the compression and expansion work shows a decreasing trend as the refrigeration temperature decreases at a fixed speed of the MTEC. The advanced exergy analysis shows a total exergy efficiency of 0.42 (with a COP of 0.62 at refrigeration temperature of −86 °C) could be expected with component improvement in the near future, and it is of the priority to increase the efficiency of the turboexpander. [ABSTRACT FROM AUTHOR]

• Performance of an ice plant is investigated with nano-refrigerant (R134a/MWCNTs). • Effect of varied mass of MWCNTs (0.05 g-0.25 g) and R134a (175 g-225 g) is studied. • Pull-down time and power consumption are reduced by 17.9%, 21.46%. • COP and cooling capacity improved by 40.09% and 11.29% respectively. • Economic analysis is also carried out, the operational cost is reduced by 7.12%. Ice plant is used for producing ice at a large scale from water filled in standard cans placed inside rectangular tanks filled with brine solution. Ice plant works on the vapour compression refrigeration (VCR) cycle, the researchers are focusing on minimizing compressor work and improving the cycle's performance by introducing nanoparticles with higher thermophysical properties. In this experimental investigation, the performance analysis of the test rig of an ice plant using varied masses of 0.05 g, 0.10 g, 0.15 g, 0.20 g, and 0.25 g of multi-walled carbon nanotubes (MWCNTs), dispersed in 250 ml polyolester (POE) oil charged with masses 175 g, 200 g, and 225 g of tetrafluoro ethane (R134a) refrigerants is carried out separately. REFPROP 9.1 software is used to obtain the properties of refrigerants. The evaluated parameters are pull-down time, cooling capacity, coefficient of performance (COP), Compressor work input, economic analysis, pressure ratio, thermal conductivity, absolute viscosity, and density. It is observed that in comparison to the pure refrigerant, the refrigerator's pull-down time and compressor work are reduced by 17.9% and 21.46%, whereas, COP and cooling capacity improved by 40.09% and 11.29% for 225 g mass of R134a with 250 ml POE respectively. In addition, thermal conductivity, density, and absolute viscosity improved at both the suction side and discharge side of the compressor. [ABSTRACT FROM AUTHOR]

• Pure, binary, and ternary refrigerants of 14 refrigerants are analyzed. • Different refrigeration systems are considered. • Pareto fronts of the COP and volumetric heating capacity are obtained. • Binary refrigerants have similar advantages to ternary refrigerants. Mixed refrigerants are widely used in heat pumps; thus, it is necessary to analyze the performance advantages of pure, binary and ternary refrigerants. In this paper, 14 kinds of pure refrigerants were selected, and 24,024 kinds of pure, binary and ternary refrigerants were obtained and analyzed. The refrigerant performance in terms of the COP and volumetric heating capacity were compared in normal, vapor injection with internal heat exchanger and with flash tank systems. In this paper, 40 °C was used as the temperature lift, and four cases with heating production temperatures of 70, 80, 90 and 100°C were analyzed. The Pareto fronts for the different refrigerant types and compositions were obtained by using exhaustive method. The COP and volumetric heating capacity exhibited contradictory trends in all cases. The results showed that mixed refrigerants had significant advantages over pure refrigerants in achieving the Pareto fronts. However, in all cases, when the COP was higher than 5, the binary refrigerants had similar advantages to ternary refrigerants; thus, ternary refrigerants were not necessary. When the COP was lower than 5, it was difficult to further increase the volumetric heating capacity by sacrificing the COP. [Display omitted] [ABSTRACT FROM AUTHOR]

Due to the increase in human population, there is an ever-increasing demand for energy in different sectors which leads to environmental problems like climate change, rise in temperature, and global catastrophes. Cooling systems have become a very essential element in recent decades for mankind. The present system focuses on the design and fabrication of a counter-flow humidification setup which uses biomass-based charcoal as the packing material. Air velocity and water flow rate have been varied along with the density of charcoal. Output parameters such as a change in pressure (ΔP), Coefficient of performance (COP), evaporation rate (ER), humidification efficiency (HE), specific cooling capacity (SCC), and energy consumption (EC) are evaluated. Performance parameters obtained for charcoal are compared with that of standard Celdek Packing. Through experiments, it is found that humidification efficiencies for Celdek and charcoal packing are 77.45% and 57.40% respectively. The overall coefficient of performance obtained is 1.41 for charcoal and 3.17 for Celdek packing. Among the three densities which were considered, charcoal packing with a density of 400 kg/m3 exhibited higher performance with respect to COP, HE, ER, and SCC. Similarly, a water flow rate of 0.4 lpm gave a maximum performance and 0.7 lpm gave the least. It is concluded that charcoal can be considered one of the highly efficient biomass-based materials contributing to sustainable energy related to cooling applications. [ABSTRACT FROM AUTHOR]

• The procedure to test magnetic refrigerators using heat exchangers is described. • A simulator has been set up to obtain the device performance using heat exchangers. • The overall heat transfer characteristic affects the suitability of the heat exchangers. • The cooling capacity is maximized at a temperature span by tuning the heat exchangers. • The external temperature affects the performance in a nonlinear way. The static performance of an Active Magnetic Regenerator Refrigerator (AMRR) can be evaluated using various indicators, such as the refrigeration capacity, coefficient of performance, and efficiency, for a given temperature span (that is, the hot-to-cold heat source temperature difference). The two main control parameters (cycle frequency and fluid mass flow rate) must be adjusted according to the imposed temperature span to achieve optimum performance. However, in real-world operations, heat exchangers at both ends of the regenerator thermally connect the device to the surroundings, and the hot and cold temperatures are no more imposed quantities. Under these heat transfer constraints, the device performance, in terms of refrigeration capacity, could be suboptimal, even after adjusting the two control parameters. Indeed, to provide optimal performance, heat exchangers must have precise values of the overall heat transfer coefficient, depending on the desired operating temperature difference. So, if a single pair of heat exchangers are used, it is impossible to characterize the performance of the magnetic refrigerator at different temperature spans. This work compares the systematic procedures for evaluating the performance of a magnetic refrigeration device either with heat exchangers at the cold and hot ends or with an imposed temperature span. Both procedures can be used to obtain the optimal AMRR performance curves. However, this work highlights the necessity to use different (or variable heat transfer coefficient) heat exchangers when the first procedure is adopted. The needed overall heat transfer characteristic of both heat exchangers will be lower for a higher temperature span. [ABSTRACT FROM AUTHOR]

• Energy, exergy and multi-objective optimization are performed for vortex tube integrated single-stage vapour compression refrigeration cycle (VTC). • The parametric investigation is done to assess the thermodynamic performance of VTC. • The cooling capacity of VTC is found to be 13.19% – 49.73% higher than that of VCR. • The maximum COP and exergetic efficiency of VTC are higher than those of VCR. • The evaporator temperature is the most influential input parameter in multi-objective optimization. This paper evaluates the thermodynamic performance of a vortex tube integrated single-stage vapour compression refrigeration cycle (VTC) in a subcritical region. The thermodynamic evaluation consists of an energy and exergy analyses for VTC in order to determine the effect of various design and operating parameters on its performance. Moreover, the results of VTC are compared with those of a simple vapour compression refrigeration cycle (i.e., VCR) for the considered range of evaporator and condenser temperatures using R1234yf as a refrigerant. The analysis reveals that the cooling capacity of VTC is 14.53% – 49.73% higher than that of VCR for the considered range of condenser temperature. Also, the maximum COP of VTC is 5.59% – 27.32% higher than that of VCR. The exergetic efficiency of VTC is 5.62% – 27.33% higher than that of VCR. A multi-objective optimization using a genetic algorithm has been conducted, which suggests that the evaporator temperature is the major decisive parameter to find the suitability of various applications of the system based on VTC. [ABSTRACT FROM AUTHOR]

• Drop-in comparison of R513A and R516A for R134a were tested in refrigeration and air conditioning conditions. • R516 proved to be more suitable for low. • Compressor volumetric efficiency, pressure ratio and superheating for R516A have a similar behavior to R134a. refrigeration temperatures. • The differences in COP of R516A are reduced by up to 5.4% compared to R134a. This paper presents the experimental energy behavior of R516A and R513A compared to R134a as baseline refrigerant in refrigeration and air conditioning temperatures. The comparative is made in an evaporating temperatures range of 261 K to 285 K with step 4 K increases, taking condensing temperatures of 308 K, 313 K, and 318 K. Results show that the best energy performance was reached by R134a while the worst were for R513A in all experimental tests, here R516A shows the smallest difference respect to R134a being just 5.4%. Also, R134a showed lower values in discharge pressure respect to its replacements, while R516A exhibited the lower discharge temperatures. R513A showed lower useful superheating for refrigeration applications, while R516A achieved the minor useful superheating for air conditioning temperatures only below R134a. Finally, R513A reached the higher value of volumetric refrigeration capacity for air conditioning temperatures at 308 K condensing temperature. All results were obtained considering the optimal refrigerant mass charge which were 682 g, 655 g, and 632 g for R134a, R513A and R516A, respectively. [ABSTRACT FROM AUTHOR]

• Energy and exergy analaysis of single and double-effect ammonia-water absorption refrigeration system powered by CPC collectors were invistigated. • Parametric optimzated based on particle swarm optimization and SVMR for different operating conditions were studied. • Machine learning was utilized to identify the optimal key performance parameters of the proposed system. • The optimization process findings showed that, at a Pe = 2.8 bar, Pg = 14.5 bar, Ta = 303.15 K, the maximum COP and exergy efficiency were 0.8483 and 0.3605, respectively, concerning the minimization of tg and te were 408 K and 267 K, respectively. • It is recommended to utilize various modeling tools, including EES and TRNSYS programs, as well as the SVMR approach as a machine learning algorithm to improve the performance of absorption chiller. The coefficient of performance (COP) and exergy efficiency of a single and double-effect ammonia-water absorption refrigeration system powered by compound parabolic concentrating collectors were analyzed under various operating situations. A novel method was proposed using support vector machine regression and particle swarm optimization to identify optimal operating parameters. The optimal pressure-temperature conditions, including evaporator pressure (Pe), generator pressure (Pg), and absorber temperature (Ta) that maximize the COP and exergy efficiency while minimizing generator temperature (Tg) and evaporator temperature (Te), were investigated. The generator temperature was the main independent variable, ranging from 370 to 470 K. The findings demonstrated that the gain in COP and exergy efficiency caused by raising the generator temperature to more than 430 K is not cost-effective. The COP increased when the evaporator temperature increased along the investigated range of generator temperatures but yielded lower exergy efficiency in all cases. The exergy destruction rate in condenser, pump, recooler, reheater, and expansion valves is insignificant compared to other components. The generator has the highest exergy destruction rate regardless of operating conditions, making it the most crucial component of the absorption system. The optimization process findings showed that, at Pe = 2.8 bar, Pg = 14.5 bar, and Ta = 303.15 K, the maximum COP and exergy efficiency were 0.8483 and 0.3605, respectively, concerning the minimization of Tg and Te, which were 408 and 267 K, respectively. The model produced an acceptable performance with a high prediction accuracy (coefficient of determination > 0.99 and mean square error < 0.0064). [ABSTRACT FROM AUTHOR]

• Homogenization-based data-driven optimization method for designing graded cellular structures is developed. • The mapping relationships among the equivalent conductivity matrices, the relative densities, and the design variables are established based on the homogenization theory. • The cellular structure is composed of a series of basic microstructures generated from corresponding microstructure prototypes. • Both 2D and 3D examples of heat conduction problems are conducted for verifying the validity and effectiveness of the proposed method. In this work, experimental tests were conducted on a domestic refrigerator to evaluate three faults with three levels: deterioration of the speed of the fan coupled to the condenser; degree of external fouling on the condenser; and area restriction on the rear cover of the refrigerator. The above, to analyze the effect of the type of fault on the performance of the refrigerator. Through a thermal analysis, it was observed that components such as the compressor and condenser presented a more noticeable variation in the thermal behavior of the refrigerant in the different faults. In fact, the fault corresponding to the fan speed was the one that caused the most inadequate performance in the refrigerator, compared to the refrigerator operating under normal conditions. The high level of this fault was reflected in an increase of 14.73 °C in the temperature of the refrigerant at the condenser inlet, it even caused an increase in the discharge pressure of 2.1 bar. Finally, this fault increased by 48% in energy consumption as well, which represented a 26% decrease in the coefficient of performance. [ABSTRACT FROM AUTHOR]

• A mathematical model has been presented to study the thermodynamic performance of the rolling piston compressor with EVI. • The suction backflow process and the injection process have been considered. • The errors between calculated and experimental results are within 4%. • The optimal injection pressure for the maximum heating capacity is slightly higher than the theoretical optimal injection pressure. • The optimal injection pressure for the maximum COP is slightly lower than the theoretical optimal injection pressure. The rolling piston compressor with enhanced vapor injection (EVI) is widely used in the household air-source heat pump system. To study the thermodynamic performance and the optimal injection pressure, this paper presents a mathematical method to simulate the whole working process of rolling piston compressor with EVI, which considers suction backflow process, discharge process, vapor injection process and leakage process. According to the calculation, the effects of injection pressure on discharge mass flow rate, p-V diagram and indicated power have been analyzed. In order to verify the accuracy of simulation, an experiment has been carried out to obtain the discharge mass flow rate and the errors between simulated and experimental results are within 4%, which shows that the proposed method is precise enough. Additionally, the experimental results show that EVI can not only improve the heating capacity and COP but also decrease the discharge temperature. However, the optimal injection pressure corresponding to the maximum heating capacity is different from that corresponding to the maximum COP. From the perspective of the heating capacity, the optimal injection pressure is a little higher than the geometric mean of suction pressure and discharge pressure but from the perspective of COP , the optimal injection pressure is a little lower than the geometric mean. [ABSTRACT FROM AUTHOR]

• Five C O2 blends have been identified, attempting non-flammability and GWP below 150. A theoretical assessment was performed varying the mixture's mass fraction and the environmental temperature. • At optimum conditions, the mass fraction of the C O2 -based blends has been optimized. • Binary mixtures C O2 /R32 and C O2 /R1270 report the best COP improvements with +21.4% and +8.7%, respectively. The extensive use of CO 2 in commercial refrigeration system has grown in the last two decade thanks to the development of new components and configurations that allows working in transcritical conditions efficiently. However, using these arrangements increases the cost and complexity of the refrigerating plant, making it challenging to implement them in medium or low-capacity systems. As an alternative, CO 2 -based binary mixtures report attractive improvements that allow for enhancing the COP of the system by minimising its complexity and maintaining the safety and environmental conditions of CO 2. This manuscript analyses five binary mixtures of CO 2 with the refrigerants R32, R152a, R1234yf, R1234ze(E) and R1270, determining the optimal mixture composition for maximising the COP of a CO 2 transcritical refrigeration plant in a wide range of environmental temperatures (0 to 40°C). Fixing the operating conditions for a medium-temperature application, the binary mixtures of C O2 /R32 (81/19% in mass) and CO 2 /R1270 (92.5/7.5% in mass) reported the best COP enhancements results with increments up to +21.4% and +8.7%, respectively, at high environmental temperatures. [ABSTRACT FROM AUTHOR]

• A novel natural vacuum desalination system integrated with solar absorption cooling. • The thermal performance of the hybrid NVD system is investigated. • The effect of the compressible flow is considered for the first time. • A validated desalination model with two optimizing approaches is developed. • Optimal COPs and the collector area for the temperature/pressure ratio are revealed. As the world's population and increasing urbanization continue to grow, freshwater needs have risen dramatically. A desalination process based on a natural vacuum and pipeline desalination method that can produce freshwater and transfer it simultaneously is designed and modeled comprehensively in this research. It has been demonstrated that the effect of compressibility is negligible for pressure and temperature ranges of the system, indicating that the first system model using incompressible flow assumption is valid. Solar thermal energy was also utilized to improve the system's efficiency. The results are investigated for three scenarios for Bandar-Abbas and the adjacent mountain, Genu. The first, second, and third scenarios are associated with the initial model based on pipeline desalination, the model utilizing solar cooling to reduce the temperature in the condensation section, and the model using solar energy to increase the temperature in the evaporation section, respectively. The results show that the highest freshwater production is estimated at 125,842,962 and 21,101,132 kg per year for a tube diameter of 2 and 1 m, respectively. Furthermore, the annual production rate of distilled water in scenarios #2 and #3 increased by 13.85% and 139.1% compared to scenario #1, with a tube diameter of 2 m. [ABSTRACT FROM AUTHOR]

• Expander-compressor boosted subcooling refrigeration system is proposed. • For different refrigerants optimum increment in COP with respect to conventional system is determined. • Heat transfer surface area of the subcooler is calculated. Many applications have made extensive use of refrigeration systems, which have a high energy requirement. Any improvement on the refrigeration systems can reduce the need for energy demand. A common method to improve the system performance is to subcool the condenser exit temperature and known as subcooling. An expander-compressor booster enhanced subcooling vapor compression cycle is proposed as an addition to the subcooling systems described in the literature. The refrigerant is split into two parts at the condenser exit: one portion expands in the expansion device to reach the necessary subcooling temperature, while the other part goes straight into a separate heat exchanger. Later, this additional refrigerant flows into the other expansion valve, the evaporator, and a booster expander-compressor to increase inlet pressure of compressor. As working fluids, six distinct refrigerants including low global warming potential (GWP) are used (namely R134a, R1234yf, R32, R290, R1270, and R600a) in simulations. The coefficient of performance (COP) and increment in COP values for each refrigerant are computed and graphically displayed for various evaporation temperatures between -10 °C and 5 °C. Furthermore, the heat exchanger analysis of subcooling heat exchanger is performed to compare heat transfer surface area and pressure drop for each refrigerant. Results indicate that R1234yf achieves the greatest performance with an increase in COP by 16.7, 19.1 and 21.8% depending on the mechanical efficiencies of the expander and compressors and as well as isentropic efficiency of the expander. By utilizing an expander-compressor with higher or lower mechanical and isentropic efficiencies, these enhancements can be raised or lowered. Heat exchanger analyses show that the pressure drop in the exchanger does not significantly affect the performance of the system. [ABSTRACT FROM AUTHOR]

• The coupled characteristics of compressor and expander are investigated. • Model of the whole air refrigerator is established by the coupled characteristics. • Effects of turboexpander inlet temperature and first stage compression ratio. • Characteristics of the air refrigerator under variable cooling capacity. Reverse Brayton air refrigerators are environmentally friendly and have broad application prospects, which can work under various conditions. In this paper, the characteristics of a open-loop air cycle for room temperature applications were investigated. The compressor and turboexpander in the cycle were modeled by numerical simulation. Based on coupled characteristics of the compressor and expander, a system model was established. The effects of the first stage compression ratio and the expander inlet temperature on the refrigerator performance were studied by experiments. The accuracy of the system model is verified by comparing with the experiments, and the maximum deviations of expander rotating speed and supplied mass flow are 3.1% and 4.83%, respectively. With the increase of the first-stage compression ratio and the decrease of expander inlet temperature, the mass flow rate of supplied air and cooling capacity of the cycle increase. The expander efficiency can be maintained near the optimal value. At the expander inlet temperature of 313.2 K, COP drops by 31.7 % when the cooling capacity is reduced from 3.34 kW to 0.74 kW. [ABSTRACT FROM AUTHOR]

• A multi-objective optimization method for COP and volumetric heating is proposed. • The performance of ternary refrigerants in different systems is analyzed. • Optimal solution under the set conditions is obtained. • The proposed method has high scalability. Vapor injection two stage cycles proved to be an effective method for heat pumps to cope with extreme conditions. COP (coefficient of performance) and volumetric heating capacity usually contradictory as two important indicators. It is necessary to provide system designers a variety of solutions to select to adapt different working conditions. This paper proposed a method to obtain the Pareto front of COP and volumetric heating capacity by exhaustive method and non-dominated sorting. This paper sets a series of equivalent conditions and range conditions to evaluate the performance of different combinations. Variables include system form, types of mixed refrigerants, mixed refrigerants components, ratio of injection. The results show that IHX (internal heat exchanger) and ternary refrigerants have advantages under the set conditions. An example and an extended case study were used to illustrate the application method of a series of optimization schemes in the Pareto front. The method proposed in this paper is not limited to the set working conditions and can be applied to other working conditions. At the same time, the Pareto front is not limited to one solution, and the system designer can select the best solution according to the actual needs from a series of solutions. [ABSTRACT FROM AUTHOR]

It is necessary that develop broad spectrum responsive and noble-metal-free photo-catalysts to produce hydrogen. Herein, a novel nitrogen doped amorphous CoP with carbon coating (N–CoP@C) photo-catalyst was prepared by phosphating the Co-alanine complex precursor for wide spectrum photocatalytic H 2 production. Nitrogen doping can adjust the electronic structure, promote photogenerated carrier separation, and enhance electronic density. The improvement of photocatalytic hydrogen evolution activity is due to the porous structure and surface carbon layer of amorphous N–CoP@C. The porous and thin slice structure can increase the specific surface area, thus providing more active sites and separating surface charges. The carbon layer can be used as an electron acceptor to suppress charge recombination and improve photocatalytic performance. The amorphous N–CoP@C-4 exhibits the highest hydrogen evolution rate of 60.91 μmol h−1 under visible light irradiation with EY as a photosensitizer and TEOA as an electron donor, which is about 46.7 and 2.8 times higher than Co-alanine and CoP, respectively. In particular, a high photocatalytic reaction stability was achieved over N–CoP@C-4 catalyst. This work provides an effective strategy for construction N–CoP@C to improve the photocatalytic activity. A novel amorphous N–CoP@C photocatalyst was prepared by phosphating the Co-alanine complex precursor for wide spectrum photocatalytic H 2 production under light irradiation. The coating of carbon layer on the surface increased the electron density on the catalyst surface and accelerated the charge transfer efficiency. The photocatalytic hydrogen evolution performance of N–CoP@C catalyst was improved by the synergistic effect of N doping and coating of surface carbon layer. [Display omitted] • Amorphous N–CoP@C photocatalyst was prepared by phosphating Co-alanine complex. • Adjusting electronic structure by doping N to accelerate charge separation efficiency. • Carbon coating increased the surface charge transfer rate of N–CoP@C. • Amorphous structure provides more active sites for hydrogen production. • EY-sensitized N–CoP@C-4 exhibits an outstanding photocatalytic H 2 evolution rate. [ABSTRACT FROM AUTHOR]

In this paper, a composite two-stage ventilation heat recovery system with heat pipe and heat pump is proposed, heat pipe is used to recover the exhaust air energy to improve the operating performance of the system under all operating conditions. The split heat pipe heat exchanger is designed and manufactured, the working characteristics and performance of the composite heat recovery system under different working conditions are tested, and it is compared with the parallel-loop heat pump ventilation heat recovery system also. The results show that the optimal working fluid charge rate of the split heat pipe used in the composite system is 50 %–60 %, the temperature efficiency of the composite system in winter is higher than 64.31 %, the heating COP is up to 7.17, and the total heating capacity is 5.09 kW. Temperature efficiency and heating capacity of the system are 4.01 %–66.6 % and 7.68 %–67.19 % higher than that of the double loop heat pump heat recovery system, respectively. • A concept of new composite two-stage ventilation heat recovery system with heat pipe and heat pump is proposed. • The split heat pipe heat exchanger is manufactured, the composite heat recovery system are tested in environment chamber. • Compared with other system, temperature efficiency and heating capacity of the system increase 4.01%∼66.6% and 7.68%∼67.19%. [ABSTRACT FROM AUTHOR]

There is a rising demand for improving and analyzing the potential of alternative designs and operating conditions of heat pumps. The current study explores and reports on the techno-economic analysis (4E – Energy, Exergy, economic and environmental viability) of a Modified Dual Source Heat Pump (MDHP) water heater under various ambient and operating circumstances. There are three functioning modes are presented for operating the system all over the day irrespective of the ambient conditions: dual source with natural convection (MDHP-DN), dual source with forced convection (MDHP-DF), and air-source forced convection (MDHP-AF). The experimental analysis targeted to assess the system's overall performance under diverse design and operating conditions all over the day. The outcomes specify that the average COP of MDHP in dual source with natural convection mode (DN) is 7% and 18% larger than that of dual source with forced convection (DF) and (AF), respectively. The regular daily COP and exergy efficiency of MDHP (with five heat-up cycles per day) are 3.24 and 54.6%, respectively. Furthermore, the investigation into the annual effectiveness of the MDHP involves analyzing simulation studies that take into account the local ambient conditions. According to the results, the MDHP system has a payback period of around 689 days and a lifetime CO 2 mitigation savings cost of approximately $178,057 compared to a conventional electric heating system. This inference implies that the suggested MDHP system can be adapted to varying weather conditions, providing active and long-term solutions compared with conventional heat pump water heating systems. [Display omitted] • Forced convection is introduced during dual and air source modes. • MDHP operates effectively irrespective of the ambient conditions. • Attains the cycle COP in the dual source mode, reaching approximately 4.12. • On regular, maintains a daily COP of approximately 3.24. • Practicability of employing MDHP for effective water heating is authenticated. [ABSTRACT FROM AUTHOR]

To overcome the drawbacks associated with conventional binary mixtures (NH 3 -H 2 O and H 2 O-LiBr) in the vapor absorption refrigeration system (VARS), salt is added to the NH 3 -H 2 O mixture. The present simulation study analyzes the influence of adding LiBr and LiNO 3 salts within a salt mass fraction range of 0 to 35% on the coefficient of performance (COP) of the NH 3 -H 2 O cycle. The simulations are conducted using Aspen Plus software. Furthermore, the influence of generator temperature on the COP and evaporator capacity of the ternary NH 3 -H 2 O-LiBr and NH 3 -H 2 O-LiNO 3 cycles are also studied. The simulation results demonstrate that adding LiBr and LiNO 3 salts improves the COP and reduces the initial temperature requirement in the generator of the VARS. Specifically, the NH 3 -H 2 O-LiBr cycle achieves the highest COP of 0.645 at an NH 3 mass fraction of 55% and a LiBr mass fraction of 25%. This represents an 8.81% improvement compared to the COP of the NH 3 -H 2 O cycle. Similarly, the NH 3 -H 2 O-LiNO 3 cycle exhibits the peak COP of 0.603 with the same NH 3 mass fraction and LiNO 3 mass fraction of 20%, which is 2.2% greater than the COP of the NH 3 -H 2 O cycle. Under similar operating conditions, the COP of the NH 3 -H 2 O-LiBr cycle is greater than that of the NH 3 -H 2 O-LiNO 3 cycle. • To address the issues with the binary NH 3 -H 2 O mixture used in absorption refrigeration cycle, LiBr and LiNO 3 salts are added. • The COP of the NH 3 -H 2 O cycle increases after adding salt, reaching its maximum at a mass fraction of 25% LiBr and 20% LiNO 3. • The addition of salt also reduces the initial generator temperature and increases the evaporator capacity. [ABSTRACT FROM AUTHOR]

Refrigeration devices designed for use in industrial environments are typically equipped with universal control algorithms, which require a minimal number of signals and parameters to ensure satisfactory device operation. These algorithms are typically of the PID type. This study elaborates upon the impact of using a dedicated hybrid controller, which was designed with specific consideration of the operating conditions of a given refrigeration device. The identified nonlinear Drycooler characteristics were used to support the controller at steady-state operating conditions. The system dynamics were supervised by a dedicated, experience-based designed hybrid fuzzy logic Mamdani type controller for both freecooling and compressor modes. The switchable configuration of the MISO control architecture results in a reduction in overshoots and oscillations in the system, a decrease in the time necessary for stabilization, a reduction in CO 2 , and an increase in control quality and energy efficiency. [Display omitted] • Historical data and experience is a key to success in the fuzzy controller design. • Custom fuzzy logic controllers and switching between freecooling and compressor modes increased efficiency and control quality. • Identified nonlinear Drycooler characteristics improved control quality. • Designed hybrid controller works effectively than built-in device controllers. • The convergent nonlinear model confirmed the correct implementation of the hybrid controller. [ABSTRACT FROM AUTHOR]

• The J-T cooler with the thin-plate type sorption compressor is fabricated. • The performance of the thin-plate type and cylindrical cells are compared. • Open and closed-loop experiments are performed without thermal load. • It is estimated that the cooling capacity of 4.9 mW can be achieved at 5 K. A sorption J-T cooler for a cooling temperature of 5 K can be useful to cool the sensitive detectors and calorimeters, due to its vibration-free characteristic. It is a J-T cooler driven by the sorption compressor, that utilizes the adsorption phenomenon to create the pressure gradient. To maximize the mass flow rate, the switchless thin-plate type cell is adopted for the sorption compressor. The coiled tube-in-tube heat exchanger is fabricated to minimize the overall size of the cooler. After precooling the experimental apparatus with a two-stage G-M cooler, the open-loop test is performed to assess the mass flow rate characteristics of the J-T restrictor and the background heat ingress. In the closed-loop experiments, the cooling temperature below 5 K is achieved by the sorption compressor without heat load. The nominal mass flow rate from the sorption compressor is 1.3 mg/s with the pressure ratio between 5.9 and 6.6. Subsequently, the model of the heat exchanger is utilized to determine the maximum cooling capacity according to the inlet temperature of the high-pressure stream. Furthermore, the effectiveness and the overall COP of the sorption J-T cooler are analyzed. The maximum cooling capacity at 5 K in the experimental setup is predicted to be 3.4 mW and 4.9 mW with the original and improved heat exchangers, respectively. [ABSTRACT FROM AUTHOR]

• Double effect adsorption cycle with adsorption heat recovery was investigated. • Adsorbent combinations were examined with the heat source temperature of 90 degC. • FAM-Z01 and FAM-Z02 for low and high temperature cycles, respectively, are the best. • COP can attain 1.0 when adsorbent mass and cycle time are selected appropriately. • The total cooling power is maximized when COP=0.9. This study investigates the performance of double effect adsorption refrigeration cycle that utilizes the adsorption heat of a high-temperature adsorbent heat exchanger for desorption of a low-temperature one. Because there is a freedom to select an adsorbent for each adsorbent heat exchanger, the combination of adsorbents such as silica gel, FAM-Z01, FAM-Z02 and FAM-Z05 were examined. The temperature of an external heat source was assumed to be 90°C. Dynamic cycle simulation was employed to estimate the performance in terms of coefficient of performance (COP) and specific cooling power (SCP). The results show that the combination of the adsorbents FAM-Z01 and FAM-Z02 for the low-temperature heat exchanger and high-temperature one, respectively, is the most effective to achieve high COP as well as high SCP. The results also indicate that the COP=1.0 is attainable when the mass allocation of the adsorbents and the cycle time are selected appropriately. From the viewpoint of maximizing the cooling power, COP=0.9 is suggested for the best design, where the mass of high-temperature side is equal to the mass of low-temperature side. [ABSTRACT FROM AUTHOR]

Background: Postural control (PC) can be affected by circadian rhythm and sleep deprivation, whereby it has been reported the result of PC measurement in clinical and experimental situations can be influenced by both factors. It has been suggested sleepiness can result in deficiency in PC, which in turn can lead to occupational accidents and subsequent injuries. This is while no study critically reviews or summarizes findings surrounding this topic in the literature.Research Question: Is there any significant effect of sleep deprivation and circadian rhythm on PC variables among healthy individuals?Methods: PubMed, Web of Science, Scopus, and Embase were used to detect relevant studies. Only studies that examined the effect of time of day and/or sleep loss on PC among healthy individuals were included in this systematic review.Results: Forty-nine studies were included based on the inclusion criteria. Both circadian rhythm and sleep loss had a significant effect on PC, whereas there are inconsistent findings for optimal postural control regarding time of day. In terms of sleep deprivation, all investigations indicated that sleep loss deteriorates PC.Significance: The current systematic review represents a significant effect of circadian rhythm and sleep deprivation on PC, whereby it is suggested that clinicians and researchers consider these factors when measuring PC since it may affect the result of research and clinical test. Moreover, PC may be worsened through sleeplessness; however, some studies revealed there is no linear relationship between time of wakefulness and deteriorating PC due to the influence of circadian rhythm. Hence, while PC, as an objective tool, can help to detect those who are sleep deprived, which in turn can lead to prevent possible musculoskeletal injuries, further studies are needed to reveal more understanding about the effect of sleep loss and circadian rhythm on PC. [ABSTRACT FROM AUTHOR]

As global efforts to address climate change intensify, industrial processes are of the highest interest due to their substantial contributions to greenhouse gas emissions and use of fossil energy. The deployment of high-temperature heat pumps (HTHPs) presents a significant potential for mitigating emissions and decreasing primary energy consumption in industrial applications. However, for widespread adoption, further technological development is crucial to enhance the technology's availability at higher supply temperatures. This study is dedicated to optimising HTHPs by exploring the intricate interplay between working fluids and heat pump cycle design, with the goal of establishing a technology portfolio that guarantees high performance across a wide range of high-temperature conditions. The research evaluates 16 working fluids in 10 HTHP configurations across a broad spectrum of high-temperature conditions, with source temperatures from 0 °C to 100 °C and temperature lifts from 20 K to 150 K. A polynomial estimating the Lorenz efficiency was proposed based on these configurations and temperature conditions. A portfolio of heat pumps using either isobutane, isopentane, or hexane, in a one-stage cycle layout with a suction line heat exchanger, a two-stage cycle layout with an open intercooler using R-718, and cascade configurations using these working fluids, consistently demonstrated the highest Lorenz efficiency for 95% of the evaluated temperature conditions. Including ammonia and carbon dioxide elevated this to 98% of temperature conditions, improving particularly at large sink temperature glides. While underscoring the necessity for an approach considering both COP and production costs, the study highlights the COP as the most important aspect. The marginal improvement observed by including HFOs highlights the potential of a natural working-fluid-based portfolio to achieve high performance, instilling optimism for the future of sustainable high-temperature heat pump applications. • Analysis of 16 fluids in 10 heat pump cycles at 1124 high-temperature conditions • Natural fluids highest COP for most industrial applications • Hydrofluoroolefins (HFOs) did not improve thermodynamic performance • Best portfolio includes butane, pentane, hexane, ammonia, water and CO 2 [ABSTRACT FROM AUTHOR]

Electrocatalytic ammonia production requires high-performance catalysts for high-efficiency cathodic nitrate reduction reaction (NO 3 RR) and rapid oxidation reaction. Herein, an advanced NO 3 RR electrocatalyst based on bimetallic Co-Fe phosphide (Co-Fe-P) hollow nanocubes is prepared, which exhibits a high NH 3 yield rate of 21.11 mg h−1 mg cat. −1 with Faradaic efficiency of 98.9 % under neutral conditions. Furthermore, continuous ammonia (>94.2 % selectivity) and lactic acid production can be obtained at lower applied voltages by using a two-electrode system integrating NO 3 RR with glycerol oxidation reaction. Based on detailed mechanistic investigations by in situ characterizations and theoretical calculations, the superhydrophilic property and dual-function centers of nucleophilicity (Co) and electrophilicity (Fe) of the FeP/CoP heterostructure interface synergistically contribute to the rapid accessibility of reactant species, reducing the energy barrier of rate-determining step (*NO→*NHO) and inhibiting the competing hydrogen evolution side reaction. This study provides deep insight into the design of high-efficiency electrocatalysts for nitrogen-neutral cycles. [Display omitted] • Hollow Co-Fe-P nanocubes are prepared for NO 3 RR to ammonia and oxidizing glycerol to lactic acid. • A high NH 3 yield rate of 21.11 mg h−1 mg−1 and a Faradaic efficiency of 98.9 % are achieved. • The hetero-interface can optimize electronic structure and endow superhydrophilic property. • Co and Fe bimetallic sites reduce energy barrier of endothermic rate-determining step. [ABSTRACT FROM AUTHOR]

Air source heat pumps have gradually become a widely used heating solution worldwide due to their advantages of high efficiency, energy conservation, and environmental protection. However, air source heat pumps also face some challenges in practical applications, such as unstable heating and performance degradation in low-temperature environments. In order to improve these problems, based on the cascade heat technology, a new type of dual-source synergetic heat pump system is designed using air energy and biomass waste heat dual heat sources. In order to study its performance, a simulation model of the heat pump system was first constructed using distributed-parameter method. In order to verify the effectiveness of the model, an 18-kW heat pump experimental unit was constructed. By comparing the three key parameters of user side outlet water temperature, high-temperature compressor power, and system coefficient of performance (COP), the results show that the maximum error does not exceed 11 %; Secondly, in order to improve the stability and operational efficiency of the system, a three-level control strategy was designed based on considering the coordination of different grade heat sources; Finally, based on the above, the operating characteristics of the heat pump system were investigated through testing under different external input conditions. The research results indicate that by utilizing cascade heating and parallel heat exchange technology, the heat pump system can achieve stable heating even under large fluctuations in external working conditions. At the same time, compared with air source heat pumps, the COP can be improved by 69.7 % in low-temperature environments. The system results not only provide reference for the design and operation of new heat pump systems, but also provide practical and feasible solutions for the problem of decreased heat pump performance in low-temperature environments. • A new type of dual-source synergetic heat pump system is designed. • A 18 kW prototype unit of the heat pump system are constructed and tested. • A three-level control strategy for regulating the heat pump system is proposed. • The proposed heating device can enhance clean energy utilization and COP greatly. [ABSTRACT FROM AUTHOR]

• TU-FLANC integrates flash-driven and heat pump tech, operating under atmospheric pressure, enhancing thermal power and temp. • Sensitivity analysis shows evaporator temp and LiBr concentration significantly affect system performance. • Optimization using differential evolution algorithm achieves optimal solution for 50°C rise, COP of 0.5282, and COPW of 0.4886. To address the current deficiencies in outlet temperature and thermal power of low-temperature heating reactors while ensuring safety and economic viability, this study introduces the Temperature-Upgraded Flash-driven Low-temperature Advanced Natural Circulation Heating Reactor (TU-FLANC). The FLANC system innovatively utilizes the flashing phenomenon of the coolant in the rising channel to significantly increase the coolant circulation flow rate and thus enhance thermal power at atmospheric pressure. The TU system employs an Absorption Heat Pump (AHP) to upgrade the temperature of the reactor's output heat. The two systems are interconnected via a Coupled System Heat Exchanger (CSHEX), achieving an upgrade in reactor thermal power and outlet temperature at atmospheric pressure. To evaluate the performance of the TU-FLANC system, a mathematical model of the system was established, and a computational program was developed. The impact of key parameters such as evaporator temperature, condenser temperature, and solution concentration on system performance was analyzed. The results indicate that the evaporator temperature and solution concentration have the most significant impact on the system's coefficient of performance (COP) and the coefficient of performance considering pump work (COPW). Through Differential Evolution (DE) algorithm optimization, the optimal solution concentration combinations were determined to maximize COP and COPW under different temperature upgrade demands. For a temperature upgrade demand of 50 °C, the optimal solution concentration combinations are 40.02 % and 57.48 %, with corresponding COP and COPW values of 0.5282 and 0.4886, respectively. The research findings highlight the significant innovative potential of the TU-FLANC system in enhancing heat power and outlet temperature. [ABSTRACT FROM AUTHOR]

Adsorption heat pumps (AHPs) have been envisioned to be the next generation of cooling systems owing to their low electricity consumption and negligible total equivalent warming impact (TEWI). This study investigated the adsorption characteristics, thermodynamic properties, and environmental impact of HFC32 onto six waste mangrove-derived activated carbons (MACs), which were synthesized at various operating conditions. Adsorption isotherms were acquired below and above critical temperatures (30, 50, 70, and 90 °C) by a high-precision thermogravimetric analyzer (TGA). Notably, the most promising sample exhibited a remarkable HFC32 adsorption capacity (2.628 kg ref per kg ads), which is a benchmark for any HFC/AC pair to date. Six sets of isotherm data were fitted with well-established Dubinin-Astakhov (D–A) and Tóth equations, resulting in a notably high goodness of fit. The isosteric heat of adsorptions was also assessed and elucidated using the ideal Clausius-Clapeyron model and modified non-ideal models proposed by Rahman et al. and Chakrabarty et al. Furthermore, a comprehensive thermodynamic and ecological footprint analysis, including the specific cooling effect (SCE), coefficient of performance (COP), Clapeyron analysis, and total equivalent warming impact (TEWI) assessment, were conducted. The implementation of the aforementioned MAC/HFC pair can potentially achieve an SCE of 457 kJ kg ads –1 for space cooling and approximately 25% reduction in CO 2 emissions. Adsorption uptake, SCE, COP, and TEWI analyses collectively emphasize the significant potential of pairing MACs with HFC32 in designing an environmentally sustainable AHP. [Display omitted] • Waste biomass-derived chemically activated carbons were experimentally investigated for HFC32 adsorption. • A record uptake (2.628 kg ref per kg ads) of HFC32 was attained onto the synthesized activated carbon material. • The origin of isosteric heat of adsorption was clarified and assessed for different distinguished models. • SCE and COP analysis reveals that the pair has a huge potential for various cooling applications. • About 25% GHG emission reduction is conceivable using HFC32 in the proposed adsorption cooling system. [ABSTRACT FROM AUTHOR]

• A novel 2D supermolecule precursor (Co-MPA) was obtained by the self-assembly. • CoP was obtained by in situ phosphating during the calcination of Co-MPA. • CoP possesses a small size of 18 nm due to the encapsulated by N-doped C layer. • The CoP/N-CNT catalyst exhibits efficient and stable catalytic performance in OER. Development of high-activity and low-cost electrocatalysts is significant to enhance the low-kinetic process of oxygen evolution reaction (OER). In this paper, we utilized the self-assembly between melamine, phytic acid and cobalt ions to obtain two-dimensional Co-MPA. Subsequently, in situ phosphating of cobalt ions to obtain CoP/N-CNT was achieved by the pyrolytic of Co-MPA. The small size of CoP (∼18 nm) and the N-doped carbon material endowed CoP/N-CNT with excellent OER electrocatalytic activity, which delivered an overpotential of 330 mV to drive a current density of 10 mA cm−2. Moreover, the TOF value of CoP/N-CNT catalyst is 4.6 times higher than the commercial RuO 2 catalyst (at the overpotential of 480 mV), providing it as a promising electrocatalyst for OER. [ABSTRACT FROM AUTHOR]

This paper presents the investigation of zeotropic binary fluid mixtures containing cyclohexane (critical temperature above 200 °C) as the base fluid with R600, R600a, R601, R601a, R1336mzz(Z), R1234ze(Z), R1233zd(E) and cyclopropane (critical temperatures between 100 °C and 200 °C). For pure components and their mixtures, the performance of the vapor compression system with an internal heat exchanger was analysed at 50 °C and 80 °C heat source and sink inlet, respectively. Variation of the heat source temperature difference and the internal heat exchanger pinch point temperature difference at supply temperatures (140–170 °C) were also investigated. A pinch point temperature difference of 5 K was maintained for the evaporator and condenser. An increase of 6.59 % in COP was obtained with the zeotropic mixture of cyclohexane/cyclopropane compared to that of pure cyclopropane. The design point analysis showed that increasing the heat source temperature difference and internal heat exchanger pinch point temperature difference reduces the COP. The adopted mixture criteria increased the performance between 3.23 % and 3.91 % with respect to standard working fluids like R1233zd(E) and R601, for a 170 °C supply temperature. With this promising thermodynamic analysis in a subcritical operation, the cyclohexane/cyclopropane mixture has prospect of full integration heat pump design. • Siloxane and cyclic hydrocarbon mixtures are suitable for heat pump (up to 170 °C). • Cyclohexane/cyclopropane mixture improved the COP of R601a heat pump by 7.16%. • COP increased at lower heat exchanger pinch point temperature difference. • Increased source temperature glide amounted to reduction in COP. • Heat pump performance strongly correlates with heat exchanger exergy destruction. [ABSTRACT FROM AUTHOR]

This study predicts the long-term performance of ground source heat pump (GSHP) systems in different climatic regions of Japan. The research model calculates the dynamic heat load of a typical Japanese building in various cities using their meteorological data, considering different schedules for heating and cooling seasons. The model aims to analyze the performance degradation of the GSHP system after 15 years of operation due to the imbalanced heating and cooling loads. Additionally, it compares ground temperature changes, coefficient of performance (COP) variations, and annual operation times based on different thermal imbalance ratios (TIR) for the case studies. The results demonstrate that TIR serves as an appropriate factor for comprehensively evaluating system aspects, including GHE length, ground temperature, and COP degradation, across various climates. It was found that ground temperatures increased by a maximum of up to 4 °C in cooling-dominated regions due to higher thermal imbalance accumulative loads, while it decreased to around 1 °C in heating-dominated regions. The model also revealed that the COP decreased in the dominant operation for each case study due to induced thermal imbalance and soil temperature change. The thermal imbalance caused the system cooling COP decreased by 0.015/year in the worst case (Okinawa City) and 0.006/year in average for other cases. (1) The climatic regions of japan and the color-coded average hourly temperature for the different cities. (2) This variety causes different cooling and heating season schedules, imbalance load, and (3) Changes the ground temperature in long-term operation. [Display omitted] [ABSTRACT FROM AUTHOR]

• For modeling non-equilibrium condensation, the wet steam multi-phase model is used. • Water is applied in ejector refrigeration cycle as economical and non-toxic fluid. • Effects of droplets injection at secondary flow causes reducing COP and ER. • In special case, the steam accompanies by droplets at the outlet of ejector. • Designers and operators should consider effects of droplets in ejector performance. Steam ejector plays a key role in the refrigeration system. The water has been used as a working fluid because water is more economical and non-toxic. The operating fluid often enters the evaporator as a water liquid and droplets evaporate by absorbing heat. Cooling load changing causes the vapor in the outlet of the evaporator to be accompanied by droplets. Therefore, there are droplets at the inlet of secondary nozzle and flow should be simulated as a wet steam flow with injection droplets at the secondary flow. In this paper, the effects of droplets injection at secondary flow have been investigated on the performance of the refrigeration cycle. For this purpose, the Eulerian-Eulerian method has been used and the results have been validated with experimental data. Six cases are considered with different wetness and number of droplets in the secondary flow. The results of case 6 show COP, T ¯ outlet , and ER decrease about 22.93%, 15.66%, and 22.93%, respectively. In addition, the steam accompanies by droplets at the outlet of ejector. Therefore, it is essential for designers and operators to model and consider the effects of the droplets on the wall erosion to optimize the wet steam ejector and refrigeration cycle performance. [ABSTRACT FROM AUTHOR]

Designing cost-effective bifunctional catalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in alkaline electrolyte remains a significant challenge. Herein, we report adding Nb to pristine CoP nanowires enhances the material's catalytic activities towards HER and OER. Density functional theory (DFT) calculation unravels that the Nb atoms not only optimize hydrogen binding abilities on CoP surface, but also modulate the surface electron densities of in situ formed β-CoOOH during anodic oxidation, thereby greatly accelerate both the HER and OER kinetics in alkaline solutions. In addition, an alkaline electrolyzer using Nb-doped CoP nanowires as cathode and anode for overall water splitting, delivers 100 mA cm−2 at low cell voltage of 1.70 V, superior to Pt//RuO 2 couple. This doping strategy can be extended to other transition metal phosphides as multifunctional catalysts towards overall water splitting and beyond. [Display omitted] • Nb doped CoP nanowires are prepared and used as catalysts for HER and OER. • Nb–CoP NWs require only 1.60 V to reach 10 mA cm−2 for overall water splitting. • CoOOH is in-situ formed in the OER catalytic process and leading to high activity. • DFT calculations reveal the Nb doping can modulate the electronic structure of CoP and enhance the catalytic performance. [ABSTRACT FROM AUTHOR]

• Drop-in comparison of R134a, R450A and R513A. • R450A heating capacity is within − 15.02 % and − 6.59 % compared to that of R134a. • R450A COP is within − 2.48 % and + 2.99 % with respect to that of R134a. • R513A heating capacity is within − 8.78 % and + 3.16 % compared to that of R134a. • R513A COP is within − 7.48 % and 2.22% with respect to that of R134a. This paper discusses the results of an experimental analysis of the use of R450A and R513A as drop-in alternatives to R134a in a water-to-water heat pump. The heat pump is tested setting the rotational frequency of the compressor shaft, the vapour superheating at the evaporator outlet and the mass flow rates and temperatures of the secondary fluids at the heat exchangers outlets to the desired conditions. Compared to R134a, the use of R450A leads to a capacity reduction, that lays in the range 6.59% to 15.02%, and to a COP variation, that is within the range − 2.48% to +2.99%, whereas with R513A the variations of the heating capacity and COP lay in the range − 8.78% to +3.16% and − 7.48% to +2.22% respectively. The increase in the rotational frequency of the compressor shaft to bring the heating capacity back to the R134a values is discussed too. The required increase is in the range 10% to 16% with R450A and 2% to 8% with R513A, but a COP reduction in the range 0.14% to 5.22% with the former refrigerant and 2.34% to 6.48% with the latter consequently arises. [ABSTRACT FROM AUTHOR]

Background: Foot orthoses are widely used in runners with pronated feet, who are characterized with large forefoot abduction and arch deformation during gait. However, the relationship between the amount of forefoot and arch orthotic correction and the alterations in foot biomechanics remains unclear.Research Question: This study aimed to determine dose-response effects of foot orthoses with forefoot wedge and arch support components on the center of pressure (COP) trajectories and pressure distribution during running in symptomatic pronated feet.Methods: Fifteen recreational runners participated in this study. A pressure plate was used to measure plantar pressures during running with control shoe only and ten foot orthoses, varying in forefoot wedges (5 levels) and arch supports (2 levels). The COP trajectory across the entire stance phase was compared between orthotic and control conditions using one-dimensional statistical parametric mapping. The differences in the force-time integral (FTI) and temporal variables were explored between conditions using repeated measures ANOVAs. The main effect of the two orthotic components and their interaction on tested variables were examined using two-way ANOVAs.Results: A forefoot wedge, whether laterally or medially located, shifted the COP trajectory laterally during some subphases of running (p < 0.05), while using an arch support only had minimal effect on the COP. Almost all orthoses reduced the FTI on the 2nd metatarsal and medial heel, and only medial forefoot wedges reduced the FTI on the hallux. There was a linear effect of forefoot wedges on the medial-lateral COP displacements during the propulsion phase, but no interactions were found between two orthotic components.Significance: These findings suggest that forefoot orthotic components rather than arch supports are effective in altering forefoot dynamics in runners with pronated feet. This study could have implications for foot orthotic prescription and running-related injury prevention for individuals with pronated feet. [ABSTRACT FROM AUTHOR]

Renewable electricity-powered hydrogen production is an attractive alternative to unsustainable industrial processes, but the large-scale implantation of such sustainable technology still requires efficient and noble-metal-free electrocatalysts for driving cathodic hydrogen evolution reaction (HER), especially under alkaline conditions. In this paper, CoP nanowire array was in-situ developed on porous graphite felt (CoP/GF) as a new 3D electrocatalyst in facilitating hydrogen evolution electrocatalysis. This CoP/GF presents outstanding HER activity, requiring a low overpotential of 130 mV to deliver a current density of 20 mA cm−2 as tested in 1.0 M KOH. Furthermore, this free-standing catalyst exhibits impressive long-term durability of up to 50 h under working conditions. • CoP nanowire array was developed on graphite felt as a 3D electrocatalyst. • CoP/GF presents outstanding hydrogen evolution reaction performance. • CoP/GF exhibits impressive long-term durability of up to 50 h under working conditions. [ABSTRACT FROM AUTHOR]