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The exploitation of highly activity oxygen evolution reaction (OER) electrocatalysts is critical for the application of electrocatalytic water splitting. Triggering the lattice oxygen mechanism (LOM) is expected to provide a promising pathway to overcome the sluggish OER kinetics, however, effectively enhancing the involvement of lattice oxygen remains challenging. In this study, the fabrication of B, Fe co‐doped CoP (B, Fe─CoP) nanofibers is reported, which serve as highly efficient OER electrocatalyst through phosphorization and boronation treatment of Fe‐doped Co3O4 nanofibers. Experimental results combined with theoretical calculations reveal that simultaneous incorporation of both B and Fe can more effectively trigger the participation of lattice oxygen in CoFe oxyhydroxides reconstructed from B, Fe─CoP nanofibers compared to incorporating only B or Fe. Therefore, the optimized B, Fe─CoP nanofibers exhibit superb OER activity with low overpotentials of 361 and 376 mV at 1000 mA cm−2 in alkaline freshwater and alkaline natural seawater, respectively. The present work provides significant guidelines and innovative design concepts for the development of OER electrocatalysts following the LOM pathway. [ABSTRACT FROM AUTHOR]

The efficacy of employing multiple cylindrical phase change materials (PCM) to enhance the performance of an air conditioning (AC) unit is examined in this study. The objective of the present study is to examine the effects of combining an AC unit with a cylindrical PCM container configuration on the PCM discharge process and the performance of the AC system. The procedure involves the connection of a heat exchanger with a cold energy storage PCM to the condenser of the AC. During the daytime, the warm surrounding air is cooled and then transmitted to the AC unit's condenser. Four different turbulence models, that is, the SST k−ω$$ k-\omega $$, standard k−ω$$ k-\omega $$, Realizable k−ɛ$$ k-\varepsilon $$ and RNG k−ɛ$$ k-\varepsilon $$ have been considered for the present computational study. The investigation has been performed for different air flow rates, that is, 33.6, 42, and 49 L/s$$ \mathrm{L}/\mathrm{s} $$ for a constant inlet air temperature of 308.15 K. The present outcomes indicate that as the flow rate rises, the air temperature inside the domain increases and the solid PCM starts melting. It is noted that complete discharging time for multi‐cylindrical PCM reduces as the air flow rate rises which are around 13.36, 11.03, and 9.94 h for airflow rates of 33.6, 42, and 49 L/s$$ \mathrm{L}/\mathrm{s} $$, respectively. The maximum achieved increase in the COP is around 94.49%, 88.68%, and 87.57% at airflow rates of 33.6, 42, and 49 L/s, respectively, for the multi‐cylindrical PCM throughout the summer. It is found that for the same temperature, as the airflow rate rises, the consumed power saving rises. [ABSTRACT FROM AUTHOR]

• 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]

This study compares the exergy of an ejector‐based two evaporator cycle (EB‐TEC) with a conventional two evaporator cycle (C‐TEC). The analysis utilizes a modified Gouy–Stodola equation, which provides a more accurate insight of the system irreversibility compared to the standard Gouy–Stodola formulation. Furthermore, the comparison includes three working fluids, that is, R134a, R1234ze, and R600 in both the cycles. The study examines the effects of varying evaporators and condenser temperatures and the dryness fraction at the exit of Evaporator 1. The data is analyzed using an Engineering Equation Solver. The findings indicate that increasing the temperature of the low‐temperature evaporator leads to a drop in exergy losses and enhancement in exergy efficiency in both the cycles. When the temperature of Evaporator 1 is increased, the total exergy of the EB‐TEC is decreased but for the C‐TEC, it is increased. Furthermore, increasing the condenser temperature results in higher exergy destruction in both EB‐TEC and C‐TEC. Notably, the maximum exergy destruction is 49.44 kW for R600, whereas the minimum exergy destruction is 14.42 kW for R1234ze in the EB‐TEC. [ABSTRACT FROM AUTHOR]

This paper proposes, for the first time, the research concept of comparing energy and economy between transcritical cycle high-temperature heat pumps and subcritical cycle high-temperature heat pumps with new refrigerants. Experiments and simulations are conducted to compare the system performance and economy of two heat pumps, and the effects of different factors on the performance of two heat pumps are analyzed. The results show that R744/R1234yf (90/10) and R515-1 are the preferred refrigerants for transcritical cycle heat pumps and subcritical cycle heat pumps, respectively. The COP of the R744/R1234yf (90/10) transcritical heat pump is generally higher than that of the R515B-1 subcritical heat pump, and compared to the R515B-1 subcritical heat pump, the cost recovery period of the R744/R1234yf (90/10) transcritical heat pump is about 9–15 years. Therefore, it is recommended that users who use heat pumps for a long time choose transcritical cycle heat pumps. Meanwhile, with the change of evaporation temperature, the system COP of the R515B-1 subcritical heat pump and R744/R1234yf (90/10) transcritical heat pump increases by 61.11% and 65.91%, respectively. In addition, the optimal charge amount for the R515B-1 subcritical heat pump is 81.8% of that of the R744/R1234yf (90/10) transcritical heat pump. [ABSTRACT FROM AUTHOR]

Designing porous carbon materials with metal phosphides as host materials holds promise for enhancing the cyclability and durability of lithium−sulfur (Li−S) batteries by mitigating sulfur poisoning and exhibiting high electrocatalytic activity. Nevertheless, it is urgent to precisely control the size of metal phosphides to further optimize the polysulfide conversion reaction kinetics of Li−S batteries. Herein, a subtlety regulation strategy was proposed to obtain ultra‐small CoP nanoparticles‐decorated hollow carbon nanospheres (CoP@C) by using spherical polyelectrolyte brush (SPB) as the template with stabilizing assistance from polydopamine coating, which also works as carbon source. Leveraging the electrostatic interaction between SPB and Co2+, ultra‐small Co particles with sizes measuring 5.5±2.6 nm were endowed after calcination. Subsequently, through a gas‐solid phosphating process, these Co particles were converted into CoP nanoparticles with significantly finer sizes (7.1±3.1 nm) compared to state‐of‐the‐art approaches. By uniformly distributing the electrocatalyst nanoparticles on hollow carbon nanospheres, CoP@C facilitated the acceleration of Li‐ion diffusion and enhanced the conversion reaction kinetics of polysulfides through adsorption‐diffusion synergy. As a result, Li−S batteries utilizing the CoP@C/S cathode demonstrated an initial specific discharge capacity of 850.0 mAh g−1 at 1.0 C, with a low‐capacity decay rate of 0.03 % per cycle. [ABSTRACT FROM AUTHOR]

The goal of the current study is to determine how the SST k−ω$$ k-\omega $$ and the standard k−ɛ$$ k-\varepsilon $$ turbulence models prediction on PCM with cylindrical configuration affect AC performance and PCM discharging when coupled with an AC unit. For simulation, 308.15 K and 318.15 K, the inflow air temperature has been considered with a fixed 33.6 L/s intake air flow rate. The low outside temperature charges the PCMs during the night. During the daytime, heated ambient air is cooled by the PCM heat exchanger before passing over the unit condenser. The present outcomes show that using the standard k−ε$$ k-\varepsilon $$ model, the cylindrical PCM has the lowest time of complete melting. The temperature contours demonstrate that turbulence occurs, particularly at higher temperatures, in the PCM melting zone within the solid region. This implies that there is increased convection in this area. The maximum improved percentage in COP increases as the rising input air temperature for both turbulence models increases. The average power saving of AC at 308.15 K of an input air temperature for 83.33 min is predicted by both the standard k−ɛ$$ k-\varepsilon $$ and the SST k−ω$$ k-\omega $$ to be 14.0905 W and 14.1089 W, respectively. [ABSTRACT FROM AUTHOR]

In this research, a dual heat source heat pump evaporator (AWSHP) with low-temperature hot water and air energy as the heat source is presented for the frosting problem of an air-source heat pump (ASHP) in low-temperature operating conditions. The critical frost region of the AWSHP system was also mapped using air temperature and water spray temperature as variables. The heat transfer characteristics as well as the anti-frost performance of AWSHP under different operating conditions were analyzed through experiments and simulations. According to the study's findings, the AWSHP system's refrigerant evaporation temperature was higher at the same ambient temperature than that of the ASHP. With AWSHP spray water volume of 8L/min and heat pump condenser circulating water volume of 15L/min, the average refrigerant heat exchanger and COP of AWSHP increased by 14.8% and 11.1%, respectively, compared with the ASHP system. At the same time, the AWSHP anti-frost operation strategy is proposed for low-temperature operating conditions. When the water spray volume was adjusted to 0.25 and 1.75 m³/h, respectively, under varying hourly meteorological conditions, the frost-free operation time was 61.21% and 89.24%, respectively. This was an improvement of 18.17% and 46.20%, respectively, compared to the ASHP. [ABSTRACT FROM AUTHOR]

Refrigerators are one of the common machines for Indonesian people. Refrigerators can be used to store foods and ingredients for longer shelf life. The temperature in the refrigerator and freezer is low because the heat is absorbed by the evaporator and then released into ambient air through the condenser. The heat transfer velocity from the condenser to ambient air depends on the convection heat transfer coefficient of air. This study was conducted experimentally by comparing the refrigerator's performance that use air-cooled condensers and water-cooled condensers. The equipment used is a refrigerator with a portable water bath. This study aims to know the temperature change speed in the storage room and freezer room, the temperature changes before and after the condenser was used, and the change of the temperature and pressure in refrigerant before and after the evaporator was used. The results showed refrigerator with a water-cooled condenser can give cooling process in the storage room faster, give freezing process in the freezer room faster, and enhance COP.

[Display omitted] Lithium-sulfur (Li-S) batteries have garnered extensive research interest as one of the most promising energy storage devices due to their ultra-high theoretical energy density. However, the sluggish reaction kinetics, abominable shuttling effect and inferior cycling stability severely restrict its practical application. Herein, a multifunctional CoP/Co@NC/CNT heterostructure host material was elaborately designed and synthesized by integrating CoP/Co heterojunction, N -doped carbon hollow polyhedrons (NC) and carbon nanotubes (CNTs). Specifically, the CoP/Co heterojunction can reconfigure the local electronic structure, resulting in a synergistic effect that enhances adsorption capacity and catalytic activity compared to CoP and Co alone. Furthermore, the CNTs-grafted NC not only provides multi-dimensional pathways for rapid electron transport and ion diffusion, but also physically restricts the diffusion of polysulfides during charge-discharge processes. Owing to these advantages, the battery assembled with the CoP/Co@NC/CNT/S cathode yields an impressive discharge specific capacity of 1479.9 mAh g−1 at 0.1C, and excellent capacity retention of 793.7 mAh g−1 over 500 cycles at 2C (∼85.5 % of initial capacity). The rational integration of multifunctional heterostructures could provide an effective strategy for designing high-efficiency nanocomposite electrocatalysts to promote sulfur redox kinetics in Li-S batteries. [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 paper presents the design of a two-stage subcritical compressor heat pump operating in an air-to-water system and running on environmentally friendly refrigerants. The pump is dedicated to buildings where there is a high-temperature central heating system and wall-mounted radiators are used as heat receivers. The first stage of the unit was supplied with R290 refrigerant and the second stage with R1234 ze(E) refrigerant. The nominal heating power of the unit is 10kW for a lower source temperature in the range -20°C÷10°C. The unit's refrigeration system was designed and simulation tests were carried out to determine the unit's operating parameters for the lower source temperature in the range -20°C÷10°C, the condensation temperature of the stage I refrigerant for values: 20°C, 25°C, 30°C and the condensation temperature of the stage II refrigerant in the range 30°C÷60°C. The value of the coefficient of performance (COP) was determined in relation to the heating power generated in stages I and II to the electricity consumed, which value, depending on the operating parameters, ranges from 2.55 to 5.6. The value of the COP related to the heating power received from the stage II condenser to the total power consumed by the stage I and II compressor, depending on the operating parameters, ranges from 1.5 to 2.9. It was found that by using a stepless adjustment of the volumetric efficiency of the stage I and II compressor, it is possible to match the heating power of stage I to the cooling power of stage II and thus increase the COP value by 50%.

At present, one of the main challenges that industry faces is its impact on global warming, linked to the greenhouse effect and ozone hole problems. These two environmental issues have not yet been solved completely and, concerning the industrial cold sector, countries are making various decisions on refrigerants. Magnetic refrigeration potentially represents a less impactful refrigeration technology. In this review, the physical basis of magnetic refrigeration is analysed, in order to propose this technology for industrial use. [ABSTRACT FROM AUTHOR]

Characterizing the optimal operating parameters for a heat pump with a specific refrigerant is paramount, as it provides valuable guidance for refrigerant selection. The temperature mismatch between cold and hot fluids in the evaporator and condenser can lead to degraded thermal performance in heat pumps with large temperature variations. To address these two key issues, we selected several pure refrigerants with varying critical temperature levels for use in a large temperature variation heat pump configuration. The corresponding thermal performance was then investigated using the Ebsilon code under fixed temperature lift conditions as the operating temperature varied. It indicates that the maximum coefficient of performance (COP) is typically achieved when the deviation factors of temperature and pressure from their critical parameters fall within the ranges of 0.62~0.71 and 0.36~0.5, respectively. Our research recommends the binary refrigerant mixture of R152a/R1336mzz(z) (COP = 3.54) for the current operating conditions, as it significantly improves thermal performance compared to pure R1336mzz (z) (COP = 2.87) and R152a (COP = 3.01). Through research on the impact of the compositional ratio of R152a/R1336mzz(z) on the thermal performance of the heat pump, we found that that the optimal ratio of R1336mzz(z) component to R152a component is 0.5/0.5. This study offers valuable guidance for selecting the most suitable refrigerants for heat pumps in practical engineering design scenarios. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the impact of solar radiation intensity on the performance of direct-expansion solar PVT heat pump systems. To this end, an experimental setup was constructed for direct-expansion photovoltaic (PVT) solar heat pump water heating systems and photovoltaic (PV) power generation systems. The system performance and main parameters were analyzed and discussed under different solar radiation intensities. The winter experiments in southern China revealed that the exhaust temperature of the heat pump unit varied considerably under clear conditions, while the back temperature remained stable, fluctuating between approximately −13.5 °C and 24 °C. In contrast, the power generation of PVT panels increased with the increase in radiation intensity, from 78.33 W to 122.68 W, for an increase of 56.6%. Furthermore, the total electricity generation of the PVT panels was higher than that of PV panels, with an increase of 8.7–8.3%. Nevertheless, discrepancies between experimental and theoretical data were observed, particularly under overcast conditions, where the back panel temperature error was pronounced. Additionally, the system exhibited enhanced stability at elevated temperatures in comparable environments, accompanied by an improvement in the system's coefficient of performance (COP) by 5.67%. [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]

The demand for heating and air conditioning is rising due to rapidly changing climatic conditions. The market for heat pumps and air conditioning systems is seeing a steady increase in low global warming potential. There is a growing need to use environment-friendly refrigerants. Contemporary Refrigerants (HCFCs) such as those found in heat pump air conditioning systems have the potential to cause global warming and ozone depletion. Using more environmentally friendly refrigerants, including hydrocarbon and blend refrigerant mixtures, is one way to lower Global Warming Potential (GWP) and Ozone depletion potential. This study examines the performance of several alternative refrigerants, including R32, R134A, R410A, R22 and R290. To examine the performance of R290, theoretical and simulation results are compared for various refrigerants while taking into account several performance parameters, including the refrigerant energy efficiency ratio, mass flow rate, coefficient of performance, cooling capacity and compressor work for One Ton of Refrigeration (1TR) air conditioners. One player with a very low GWP is R290. However, the only drawback is that it can catch fire and is hazardous to use in splittype commercial heat pump air conditioning applications. The environmental and thermo physical properties of R290 are significantly better than those of other materials, according to theoretical and simulation studies utilising Cool Pack software, hence it is a viable replacement. [ABSTRACT FROM AUTHOR]

Indirect evaporative coolers (IECs) use the latent heat of water evaporation to cool air. This system has the advantage of operating at low power without a compressor and does not increase the absolute humidity of the air. However, an IEC is difficult to use on its own because its cooling capacity is limited by the theoretical constraint of the wet-bulb temperature of the ambient air. Therefore, an air conditioning unit (ACU) was integrated with an IEC and experimentally evaluated in this study. The dry and wet channels of the IEC were integrated with an ACU evaporator and a condenser, unlike previous studies where IECs were integrated solely with either an evaporator or a condenser. This reduced the cooling load on the evaporator and helped the condenser to dissipate heat to improve the performance of the existing ACU. In addition, the IEC was equipped with baffles to improve its performance. To assess the extent of the performance improvement due to integration with the IEC, comparisons were also performed under the same experimental conditions with an ACU only. The results showed that under conditions with an indoor temperature of 32 °C, integrating the IEC with the ACU increased the average cooling capacity by 13.1% and decreased the average power consumption by 8.60% during the test period, compared to using only the ACU. Consequently, the average coefficient of performance (COP) increased by 19.5% compared to using only the ACU under the same conditions. [ABSTRACT FROM AUTHOR]

A novel approach is proposed for optimal designing two-stage thermoelectric coolers using the biogeography-based optimization algorithm. For the comprehensiveness of the research, both types of two-stage coolers, including electrically serial and separated stages, have been investigated. Using the proposed procedure, first by selecting the most important performance parameters of the cooler, i.e. COP and the cooling capacity as objective functions, the efficiency and the validity of the approach are proved by comparing the results with results of the previous researchers. In all the examined cases, the proposed approach has led to the enhancing of the cooler performance. The results of single-objective optimization showed that using the proposed method, the cooling capacity and COP can be improved up to 17 % and 8.5 % compared to the previous designs, respectively. In the following, multi-objective optimization of thermoelectric coolers is conducted, taking into account both the objectives of the COP and the cooling capacity. Finally, Pareto optimal solutions and the exergetic efficiency of the optimized cooler were calculated for different values of the weight factor of the multi-objective function. The results of multi-objective optimization showed that by increasing the COP weight factor in the objective function, the exergetic efficiency of the refrigeration system enhances. [ABSTRACT FROM AUTHOR]

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Water source heat pumps are devices that can produce heating or cooling in the place using the energy in the ambient water which serves as the easiest source of heat. The heat pumps, which utilize the ambient water on the boiling side, are able to transfer the energy they have obtained to the water or air on the load side. The renewable geothermal energy, which is produced by the alternative energy sources, is also an important potential in Turkey as a sustainable and environmental-friendly source. The subject of utilizing geothermal energy has been among the most balanced and high efficiency, low maintenance comfortable energy sources in pace with the technological developments of the heat pumps. The widespread and daily use of the ground source heat pumps and the examination of the situation in Turkey lead us to the determination of the potential applicability which is one of the important issues. In this study, the COP of various parameters and different levels of the water source heat pumps were calculated according to the Taguchi experiment design. [ABSTRACT FROM AUTHOR]

The quest for electrocatalysts that are both stable and efficient for seawater oxidation is intriguing yet presents significant challenges. Herein, we present a hierarchical NiFe-LDH@CoP core–shell array on carbon cloth (NiFe-LDH@CoP/CC) for efficient oxygen evolution reaction (OER) in an alkaline seawater electrolyte. The NiFe-LDH@CoP/CC array exhibits remarkably low overpotential of 251 mV to achieve current density of 500 mA cm−2. Moreover, it features a modest Tafel slope of 24.9 mV dec−1. Importantly, this electrocatalyst sustains its robust stability during continuous electrolysis for 300 h at 500 mA cm−2. The outstanding performance and unique hierarchical structure of the NiFe-LDH@CoP/CC array provides innovative insights for the development of efficient electrocatalysts tailored for seawater oxidation applications. [ABSTRACT FROM AUTHOR]

Drying agricultural produce consumes a considerable amount of energy. As an energy-efficient system, a heat pump can improve the energy efficiency of the drying process and hence reduce the energy consumption, especially in South Africa, where both sub-tropical and temperate weather conditions dominate. The objective of this research is to experimentally investigate the impacts of weather conditions on the operational conditions and thermal performance of an open-loop air-source heat pump drying system. The experimental investigation was conducted in a climate chamber where the climate conditions were simulated from −10 °C to 20 °C with an interval of 10 °C for the typical temperature range of the harvesting season in South Africa. The findings indicate that ambient temperatures have a significant impact on both the operating conditions and thermal performance of an open-loop heat pump system; the change in ambient temperatures from −10 °C to 20 °C leads to a 141.6% improvement in the suction pressure, a 214.2% increase in the discharge pressure, and 30.1% increase in the compression ratio, as well as a consequent increase of 130.6% in the refrigerant mass flow rate (from 0.0067 to 0.0155 kg/s), resulting in a corresponding increase in the coefficient of performance (COP) of the heat pump drying system by about 42.1%. Therefore, this study suggests that, while using an open-loop air-source heat pump drying system utilising R134a refrigerant is feasible in South Africa, it may be practically limited to regions with warm climates or during warmer seasons. [ABSTRACT FROM AUTHOR]

Measuring postural control in an upright standing position is the standard method. However, this diagnostic method has floor or ceiling effects and its implementation is only possible to a limited extent. Assessing postural control directly on the trunk in a sitting position and consideration of the results in the spectrum in conjunction with an AI-supported evaluation could represent an alternative diagnostic method quantifying neuromuscular control. In a prospective cross-sectional study, 188 subjects aged between 18 and 60 years were recruited and divided into two groups: "LowBackPain" vs. "Healthy". Subsequently, measurements of postural control in a seated position were carried out for 60 s using a modified balance board. A spectrum per trail was calculated using the measured CoP tracks in the range from 0.01 to 10 Hz. Various algorithms for data classification and prediction of these classes were tested for the parameter combination with the highest proven static influence on the parameter pain. The best results were found in a frequency spectrum of 0.001 Hz and greater than 1 Hz. After transforming the track from the time domain to the image domain for representation as power density, the influence of pain was highly significant (effect size 0.9). The link between pain and gender (p = 0.015) and pain and height (p = 0.012) also demonstrated significant results. The assessment of postural control in a seated position allows differentiation between "LowBackPain" and "Healthy" subjects. Using the AI algorithm of neural networks, the data set can be correctly differentiated into "LowBackPain" and "Healthy" with a probability of 81%. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to explore the impact of irritating sounds on the postural control of healthy adults, considering both linear and nonlinear parameters, subjective assessments, and gender differences. Methods: Thirty-four young participants (17 females, 17 males) completed three 30 s bipedal standing stability tests on a balance platform: one with visual control (EO), another without visual control (EC), and a third without visual control but accompanied by irritating sounds (ECS). Additionally, participants filled out a questionnaire evaluating their sound sensitivity. Linear and nonlinear parameters from each balance test were considered for statistical analysis. Results: The findings reveal significant gender-based variations in sensitivity to sound, with women exhibiting higher sensitivity. No statistically significant differences in postural control were observed between males and females, except for a notable increase in irregularity (SampEn values) in the anterior–posterior direction for females in the ECS trial. Correlation analyses revealed a moderate and statistically significant correlation between SampEn values in the AP direction and SE scores. Conclusions: This study highlights the intricate relationship between sensory stimuli, attention, and the body's ability to maintain balance. The presence of irritating sounds led to increased irregularity in postural control, particularly in the absence of visual control. [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 the medical field, refrigeration systems are used to store and transport vaccines, blood, and other medical supplies that require specific temperature ranges to remain effective. As technology continues to advance, the demand for more efficient and sustainable refrigeration systems is also increasing. The freezer compartment is typically designed to maintain a temperature of −18°C to −23°C for storing frozen items. Consequently, this work aims to develop a hybrid refrigeration system that combines a thermoelectric cooler system (TEC) and a vapor compression refrigeration cycle (VCC) system to achieve lower temperatures than conventional refrigerators. Also, the performance of the proposed hybrid refrigeration system is experimentally assessed with various operating conditions, including varying the voltage delivered to the system. The experimental results exhibited that the temperature inside the freezer room reached −33°C, while the cold side temperature is −47°C. Also, the maximum coefficient of performance of the VCC system, TEC, and hybrid system is 2.07, 1.06, and 0.37, respectively, at a DC voltage applied of 6 V. Moreover, the results revealed that the hybrid system combining a TEC and a VCC system can be a valuable technology for specific applications with low temperatures and limited capacity requirements. [ABSTRACT FROM AUTHOR]

CoP nanoparticles confined in PBA-derived nanocubes supported on MXene for efficient electrocatalytic water splitting. [Display omitted] • Simply synthesis method: Simple coprecipitation-phosphatization two steps to synthesis the heterojunction between CoP and Ti 3 C 2 T x MXene (CoP/Ti 3 C 2 T x). • Outstanding electrochemical performance: The catalyst CoP/Ti 3 C 2 T x exhibits impressive overpotentials of 103 mV and 312 mV for HER and OER, respectively, to afford 10 mA cm−2 in 1.0 M KOH and maintain for 24 h. • Thorough theoretical calculation verification: The DFT calculations reveal that the introduction of Ti 3 C 2 T x MXene can significantly enhance the electrochemical performance towards water splitting. The exploration of bifunctional catalyst with economic, durable, and efficient performance plays a crucial role to boost both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in overall water splitting. Herein, we report a feasible strategy to design effective heterostructure between CoP and Ti 3 C 2 T x MXene (denoted as CoP/Ti 3 C 2 T x). This approach allows for the growth of CoP nanoparticles with uniform size of 5 nm on the Ti 3 C 2 T x MXene, further enhancing the water electrolysis efficiency. The CoP/Ti 3 C 2 T x bifunctional catalyst demonstrates an exceptional HER activity with a satisfactory overpotential of 103 mV at 10 mA cm−2, and also can drive 10 mA cm−2 for OER with the overpotential of 312 mV in 1.0 M KOH. Moreover, the CoP/Ti 3 C 2 T x -based electrolyzer exhibits high electrochemical stability for 24 h with a low required voltage of 1.66 V at 10 mA cm−2. The density functional theory (DFT) calculations reveal that the introduction of Ti 3 C 2 T x MXene significantly adjusts d-band center towards Fermi level and expand total density of states, resulting in great electrical conductivity, enhanced water adsorption, and activation. This study provides an available mode for effective design and construction of non-noble-metal-based dual-functional catalyst toward practical energy conversion. [ABSTRACT FROM AUTHOR]

The paper presents the design of a two-stage subcritical compressor heat pump operating in an air-to-water system and running on environmentally friendly refrigerants. The pump is dedicated to buildings where there is a hightemperature central heating system and wall-mounted radiators are used as heat receivers. The first stage of the unit was supplied with R290 refrigerant and the second stage with R1234 ze(E) refrigerant. The nominal heating capacity of the unit is 10 kW for a lower source temperature in the range-20÷10 °C. The unit›s refrigeration system was designed and simulation tests were carried out to determine the unit›s operating parameters for the lower source temperature in the range -20÷10 °C, the condensation temperature of the stage I refrigerant for values: 20 °C, 25 °C, 30 °C and the condensation temperature of the stage II refrigerant in the range 30÷60 °C. The value of the coefficient of performance (COP) was determined in relation to the heating capacity generated in stages I and II to the electricity consumed, which value, depending on the operating parameters, ranges from 2.55 to 5.6. The value of the COP related to the heating capacity received from the stage II condenser to the total capacity consumed by the stage I and II compressor, depending on the operating parameters, ranges from 1.5 to 2.9. It was found that by using a stepless adjustment of the volumetric efficiency of the stage I and II compressor, it is possible to match the heating capacity of stage I to the cooling capacity of stage II and thus increase the COP value by 50%. [ABSTRACT FROM AUTHOR]

The exploration of new heterojunction materials is of great significance in reducing the cost of existing noble metal catalysts and thus realizing the large-scale application of electrocatalytic hydrolysis technology. Herein, a novel CoP/CoMoP2 heterojunction was synthesized and served as a hydrogen evolution reaction (HER) electrocatalyst. The heterojunction has morphology of nanoporous structure, which is conducive to exposing more active sites and facilitating bubbles transport. The charge distribution is optimized by a strong interface interaction between CoP and CoMoP2. The catalyst's conductivity and the adsorption properties of the intermediates have both been enhanced. CoP/CoMoP2 demonstrates excellent HER activity with an overpotential of 93.6 mV at 10 mA·cm−2, which is competitive with the reported performance of analogous electrocatalysts. This work provides insights into the development of innovative phosphide-based heterojunction electrocatalysts. [ABSTRACT FROM AUTHOR]

This study offers a comprehensive thermodynamic analysis of a cascade refrigeration system conducted for low-temperature applications, focusing on the use of low-GWP and zero-ODP refrigerants to improve efficiency and sustainability. The target of this study is to explore the performance of the system using a combination of refrigerants: low-temperature cycle refrigerants such as R744, while high-temperature cycle refrigerants such as R717, R1234yf, R1234ze(E), R1336mzz(E), and R1336mzz(Z), respectively. The ECS model incorporating in REFPROP 10.0a tool was utilized to extract the data through coding for analysis. The assessment of this system involves the examination of various parameters such as its coefficient of performance, total compressor workload, total exergy, and exergy efficiency across various operational conditions. The results are compared with and without superheated and subcooled conditions to understand the impact of these parameters on the system performance. The system with R744 in the low-temperature cycle and R717, R1234yf, R1234ze(E), R1336mzz(E), and R1336mzz(Z) in the high-temperature cycle provides a higher COP and lower total compressor work compared to the conventional cascade refrigeration system. In optimal CRS, the R744-R717 pair attains the highest COP of 2.05 at the lowest possible compressor work from 9.53 to 4.87 kW than other refrigerants pair while evaporator temperature shifting from −55 °C to −20 °C. The exergy efficiency of R744/R717 is found at 26.47 % at an evaporator temperature of −55 °C, but it extends to a peak of 51.73 % at −20 °C. The study also shows that the superheating and sub-cooling of the refrigerants have a significant impact on the performance of the cascade refrigeration system. Superheating and sub-cooling at 10 °C, improves the COP of the system by reducing the compressor work and increasing the heat transfer efficiency. The research offers valuable insights into the system’s thermodynamic performance when employing low GWP refrigerants in low-temperature applications. These findings have the potential to guide the design and optimization of cascade refrigeration systems over the range of low-temperature applications.

The direct expansion solar heat pump (DX-SHP) is a competent and sustainable option for domestic heating and drying applications. The solar collector-evaporator is a vital component of DX-SHP, which operates on solar energy and low-temperature ambient energy. The heat collection capacity, coefficient of performance, and evaporation temperature are used to quantify its performance. In this context, a systematic literature review on recent advancements in the collector-evaporator of DX-SHP is presented. This paper highlights and discusses the various configurations of solar collector-evaporators, theoretical and experimental investigations, and the selection method of eco-friendly refrigerants. The impact of different performance factors, such as ambient conditions, structural parameters, and types of refrigerants, on solar collector-evaporators is also reviewed. The optimal range for solar radiation, wind speed, and temperature is found to be 350 W/m2-700 W/m2, 0.5 m/s -2.5m/s, and 5°C to 35°C. The DX-SHP system produces hot water from 15°C to 60°C, with an average COP of 1.5 to 4.5. The finned solar collector-evaporator with R290 refrigerant performs optimally in various climatic conditions. Integrating solar collector-evaporators with innovative technologies such as microchannel, heat pipe, thermoelectric generators, photovoltaic thermal collectors with compound parabolic and Fresnel lenses can improve the system's performance. In this review, researchers can find scope for performance enhancement of the collector-evaporator used in DX-SHP.

To assess and forecast the operational performance of a modified car seat for thermal management using an air conditioning system, statistical and machine learning (ML) models were used. By extending evaporator/condenser coils beneath the back and cushion surfaces of the car seat and using operational data on the HVAC system, such as seat temperature readings, an interval of operation was gathered. Using a data mining approach, statistically relevant factors and varying the compressor speed from 500 to 1600 rpm under various scenarios to model the system were selected. Utilizing key feature variables, our data-driven approach yielded predictions with favorable accuracy for the Coefficient of Performance (COP) of the HVAC system. By using the Akaike Information Criterion (AIC) to improve the Linear Regression (LR) model, the Root Mean Square Error (RMSE) dropped to 0.20, the Mean Absolute Error (MAE) dropped to 0.16, and the Coefficient of Determination (R2) increased to 98 %. The Random Forest (RF) model, optimized with hyperparameters, demonstrated moderate predictive capability, with RMSE (0.52), MAE (0.37), and R2 (94 %). Furthermore, polynomial feature augmentation, individual and combined predictor analysis, and iterative predictor combinations all improved predictive accuracy. Detailed information on the algorithms was given for the sake of other researchers.

Unpacking the experience of Ecojesuit as a global network helps in exploring new ways of collaborating across institutions and committed individuals for better participation in global processes. Ecojesuit, a tiny voice at the fringes of the United Nations (UN) meetings on climate and sustainability, adds effort to the broader social commitment for global action. It connects with other organizations sharing goodwill, capacities and voices caring for our common home and those struggling in the local context of climate disasters. While COP28 has been a great disappointment for those seeking fossil fuel phaseout, research of the International Panel on Climate Change (IPCC) is increasingly upheld. Such participation in international relations deepens the Jesuit Universal Apostolic Preferences (UAPs) and Jesuit regional Conferences in apostolic planning. The process of growing a Jesuit network of broad collaboration takes decades; each revision involves greater participation and inclusion of present realities and meaning in life.

Synthetic refrigerants are being phased out gradually in accordance with international environmental protection protocols because of global warming and ozone layer depletion. Adopting R290/R600 refrigerant, an environmentally friendly refrigerant, to replace R134a, a high global warming potential refrigerant, provides one of the solutions. In this study, exergy analysis of R134a and TiO2 suspended with lubricant and R290/R600 with a composition of 60% R290 and 40% R600 (60:40) was investigated in vapour compression system (VCRS) using R290/ R600 in TiO2 nanomixture lubricant and compared with R134a and R290/ R600 in pure lubricant. At the inlets and outlets, the main components of the VCRS are connected to temperature and pressure sensors to measure the inlet and outlet temperatures and pressures. The results obtained were used to analyses the exergy losses at various VCRS components (compressor, condenser, evaporator, expansion valve) were investigated to determine the refrigerator’s total exergy destruction (E·xdest.Total) and efficiency (ηex). The E·xdest.Total of R290/R600 in pure lubricant and R290/R600 TiO2 nanomixture lubricant was reduced by 26.9% and 42.3%, respectively, and system ηex increased by 27.7% and 38.9% respectively when compared to R134a in the system. Hence, TiO2 suspended with R290/R600 is potential a substitute for R134a.

Abstract The performance of an ejector-assisted condenser outlet split dual-evaporator cycle is compared with a conventional dual-evaporator cycle albeit consisting a pressure reducing valve. The cycles do not employ any separator due to its inability to efficiently separate the liquid and the vapor phases. The comparison of both the cycles has been made for the same cooling capacity in low-temperature evaporator and unit flow rate of R134a and R1234yf as refrigerants. The impacts of changing the operating temperatures of evaporator and condenser have been examined in the current investigation. The study reveals that with the increase in temperature of the high-temperature evaporator, the cooling capacity of the high-temperature evaporator yields, while that of the low-temperature evaporator plummets in both the cycles. Further, the compressor work is allayed in the ejector-assisted cycle; thus, the COP is enhanced considerably. The percentage COP improvement over the basic cycle is obtained from 14.7 to 17.53% for the refrigerant R1234yf and from 14.45 to 17.32% for R134a; however, the COP of both the cycles with R12134yf is slightly lower than with R134a. The ejector has been modeled assuming a constant pressure theory. The observed trend indicates that the entrainment ratio is improved with the rise in the temperature of low-temperature evaporator, whereas it is decreased with the rise in the temperature of high-temperature evaporator.

Auto-cascade refrigeration systems are the most employed systems for ultra-low temperature applications, especially for small capacity systems. Recent investigations have allowed to analyze them energetically and thermodynamically, starting a research line focused on enhancing their energy performance from experimental approaches. This work focuses on the energy optimization of a real auto-cascade system working with the mixture R600a/R1150 [70/30 %], which has been evaluated using two compressor models for R404A and R290 as well as the optimization of the two capillary tubes used in the system. Results indicate that overall efficiency of the R290 compressor is up to 21 % higher than with R404A, leading to COP increments between 35 and 81 %. Optimum capillary lengths have been determined in terms of COP and energy consumption, reaching similar values, however, the inner parameters of the system change as function of these lengths, which needs to be considered in prototypes design.

ABSTRACTThe present work focuses on the construction of a counter flow dehumidification test rig where calcium chloride liquid is used as the desiccant and is made to spray on the novel organic packing made of wood shaving with different densities and porosities. The mass flow rate of the air is varied and the performance parameters such as moisture removal rate (MRR), dehumidification effectiveness, coefficient of performance (COP), sensible heat factor (SHR) and mass transfer coefficient have been investigated. Results demonstrated an increase in the relative humidity, mass transfer coefficient and drop in the COP, MRR and dehumidification efficiency with the increase in the flow airflow rate. On increasing the CaCl2 concentration, dehumidification performance parameters such as MRR, COP and mass transfer coefficient are found to be increased. Out of the three different densities tested, 500 kg/m3 shows best performance with MRR, ΔRH and dehumidification effectiveness being 9.7%, 18.7% and 4.9% lower than the Celdek pad when measured at 5 m/s of air velocity for 30% desiccant concentration. Optimisation of the input parameters has been done and the results revealed that air velocity should be maintained within the range of 4–5 m/s to minimise energy consumption and optimum performance.

In this paper, a combined air/water source heat pump water heater is presented. At ordinary time, the heater can be used for hot water heating in water-source mode to improve the energy efficiency. While in cold season, it gives priority to air-source mode for water heating to improve operational safety. Experiments were conducted to investigate the thermodynamic performance of the heater in each operation mode, and the experiment results were analyzed. The research indicated that its operation was reliable during the long-time running. This paper offers a promising energy-saving method in future. [ABSTRACT FROM AUTHOR]

Compared with the single-stage compression, the two-stage compression cycle shows high efficiency and application potential under both severe heating and refrigerating conditions. Therefore, to improve the performance of the two-stage vapor-compression cycle furtherly, this study introduces three ejector-assisted two-stage compression cycles (E1, E2, and E3), and a conventional two-stage vapor-compression cycles (C1) also selected as the comparison. The energetic and exergetic efficiency of the systems using various refrigerants (R152a, R1234yf, R32 and R290) is investigated and compared based on the validated theoretical model for both the severe refrigerating and heating application. The result shows that the ejector improves the system's performance significantly. Under the refrigerating mode, System E3 using R32 is recommended to be applied. Compared with Systems C1, E1, and E2, the maximum refrigerating coefficient of performance (COPR) of System E3 using R32 is improved by 16.1, 12.4, and 9.1%, respectively, with the evaporation temperature of −40 °C and condensation of 30 °C. Systems E2 and E1 using R152a are recommended under the heating mode. Compared with Systems C1 and E3, the heating coefficient of performance (COPH) of Systems E1 and E2 using R152 is improved by 3.0 and 4.5%, respectively, with the condensation temperature of 70 °C and evaporation temperature of −5 °C. The result provides a deep understanding of the potential advantages of the ejector-assisted two-stage compression cycle applied in the refrigerating and heating field. [ABSTRACT FROM AUTHOR]

Applying the fuzzy logic method to FMEA and its correlation with performance investigations is rarely applied in analyzing refrigeration system risk. The aim of this study is investigate the refrigeration system performance and analyze the risk of failure mode in the performance of the refrigeration system using the fuzzy-FMEA method. In calculating performance, the COP parameter is needed. Prioritization of failure modes uses conventional FMEA (C-FMEA) and fuzzy-based FMEA (Fuzzy-FMEA), which produces conventional RPN (C-RPN) and fuzzy-RPN (F-RPN). Pareto diagrams are used to classify RPN categories which are the main causes. The result of the study is that the calculation of the refrigeration system performance shows a decreasing trend with increasing operating time. In the risk analysis, it was found that the F21 (evaporator) failure has the same rating, and the highest is C-RPN (252) and F-RPN (750). Five categories need to be mitigated. The application of fuzzy-FMEA determines the critical failure priority of the evaporator. The results of this study provide new insights into developing engine performance investigations by determining critical failure modes to get mitigation quickly by minimizing expert opinion expertise. [ABSTRACT FROM AUTHOR]