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Fusion reactions on the cathode surface of glow discharge deuterium–deuterium fusion neutron sources contribute significantly to the neutron production rate (NPR). While the NPR shows a linear relationship with current in the low current regime, a rise in cathode temperature in the high-current regime causes stagnation of the NPR. This tendency may be caused by high-temperature-induced desorption of deuterium on the cathode. This study aims to clarify the relationship between NPR and deuterium desorption. The present study utilized a water-cooling system to prevent deuterium desorption on the cathode. A stainless-steel 304 cathode and a diamond-like carbon (DLC)-coated cathode were tested. The cooling system kept the cathode temperature below 315 K throughout the experiment. In the case of the DLC-coated cathode, the water-cooling system improves the NPR in a high-current regime (30 mA or more in the present study). At 50 kV and 60 mA, the NPRs were 1.87 × 106 and 8.39 × 105 (n/s), with and without water cooling, respectively. Furthermore, without the cooling system, the NPR correlation with the cathode temperature indicates good agreement with the estimation model of deuterium desorption on the DLC-coated cathode. This study demonstrates that suppression of deuterium desorption in the cathode improves NPR, especially in the high-current regime. [ABSTRACT FROM AUTHOR]

To address the challenges faced by designers of multi-field coupled cooling systems for high heat flux chips, this paper proposes a "near-source" microchannel cooling strategy and establishes a thermal–flow-force electrically coupled model for chips. The effects of chip Joule heat and cooling water flow rate on the cooling performance with respect to multi-field coupling effects were studied. The impact of multi-field coupling effects was revealed, and a method for enhancing microchannel cooling performance in light of multi-field coupling effects is proposed. The results indicated that considering multi-field coupling effects in the microchannel cooling process leads to a deterioration in the thermal performance of chips, accompanied by a significant increase in electrical fluctuations and thermal deformation amplitude. Compared to chips upstream of the cooling water, chips downstream subjected to thermal cascade effects were more sensitive to multi-field coupling effects. Moreover, the temperature variance index, output current, and strain energy density of high heat flux chips were positively correlated with Joule heat but inversely proportional to the Reynolds number of the cooling water for cases in respect of multi-field coupling effects. Additionally, serpentine microchannels maximized the operational performance of high heat flux chips by reducing temperature of chip by up to 55.1%, decreasing strain energy density by 96.7%, and increasing input potential by 120%. [ABSTRACT FROM AUTHOR]

Thermal comfort is crucial for indoor environmental quality, impacting occupant well-being and intellectual productivity. Despite the widespread use of HVAC technologies in residential and commercial buildings, there is growing awareness of thermal comfort, leading to more studies on this issue. According to international publication indexes nearly 60% of publications belongs to the categories of construction building technology, energy fuels, and civil engineering. It should also be noted that 40% of world energy consumption pertains to construction sector. In this context, radiant cooling and heating systems come forward with their low exergy destruction rates pointing out the potential to be energy-efficient due to their higher and lower operation temperatures. Displacement ventilation, with its low heating and cooling capacity, has not gained widespread preference. However, the increasing consciousness of global warming and energy efficiency, along with the fear of airborne virus contamination, views stand-alone or hybrid applications of radiant heating/cooling and displacement ventilation as potential future solutions. This review study investigates the impact of radiant heating/cooling and ventilation types, mixing, and displacement on thermal comfort performance, focusing on factors affecting thermal comfort in trending radiant cooling and heating applications like radiant walls, ceilings, and floors. The study emphasizes the importance of considering occupant preferences, building characteristics, and energy efficiency when choosing the most suitable heating and cooling systems for different indoor environments. Stand-alone and hybrid applications of radiant heating/cooling and displacement systems can enhance thermal comfort performance, with the exception of specific cases requiring a high thermal load or ventilation rate. [ABSTRACT FROM AUTHOR]

Multi-split backplane cooling, a typical rack-level cooling technology, has the advantage of solving local hot-spot problems with huge energy-saving potential. These systems adopt the multi-split mode, and the operation effect is affected by terminal control performance. However, there are factors in the operation process, such as superheat degree (SH), rack airflow, evaporating/condensing pressures, etc., which improve the control complication, particularly under large head load differences among different terminals. Therefore, appreciative control strategies for outlet air temperatures of terminal evaporators, including single-loop control limited by minimum stable superheat degree (SLC) and fan/electronic expansion valve (EEV) double-loop control (DLC), are proposed considering that cooling performance can be affected by both refrigerant flow and airflow. Then, comparative simulation studies are carried out to evaluate energy efficiency, control effect, and feasibility under the condition of different server heat distribution characteristics. Results indicate that the DLC strategy achieves 23 % higher energy efficiency than the SLC strategy with a better temperature control effect when the inlet air temperature (IAT) difference between terminal evaporators is within ±5K. The SLC strategy has better reliability by more stable control of SH at IATs below 42°C, but it may lead to cooling failure when IATs exceed 42°C. An insufficient liquid supply problem may happen to the evaporator adopting the DLC strategy when the IAT is too high, which can be solved by adjusting the pressure differential between the evaporator and condenser. Moreover, the DLC system exhibits intense coupling effects, and how to decouple it is worthy of further study. [ABSTRACT FROM AUTHOR]

In cold, moisture-rich winter environments, window fogging represents a substantial safety hazard for drivers. Electric vehicles often incorporate heat pump systems to address challenges such as dehumidification and heating specific to cold weather. Therefore, it is essential to evaluate the dehumidification and heating efficiency of these systems through focused research. This study presents a dual-evaporator heat pump system designed specifically for electric vehicles, equipped with two distinct modes for dehumidification and heating. The research examines how factors such as inlet air volume and the degree of opening of the electronic expansion valve affect the system's dehumidification and heating performance. Experimental analyses were conducted to explore the system's response under various conditions of inlet air humidity and compressor speed in both modes. Results suggest that increasing inlet air volume improves dehumidification effectiveness but may reduce heating performance. Likewise, a wider opening of the electronic expansion valve enhances heating but could decrease dehumidification efficiency. Importantly, the study indicates that when the relative humidity of the inlet air exceeds 70 %, a single evaporator mode is more effective for dehumidification. However, when the relative humidity is below 70 %, the dual evaporator mode is more advantageous, showing better heating performance. [ABSTRACT FROM AUTHOR]

Refrigeration technology contributes to 10∼15% of global energy consumption, resulting in significant carbon emission. Solar-driven ejection-compression refrigeration system is promising for reducing electricity consumption and carbon emissions. However, existing solar ejection-compression refrigeration systems suffer from drawbacks of low heat utilization efficiency, oversized solar collectors, and thermal leakage due to large temperature differences of storage devices. Addressing these challenges, this study proposes and investigates a new solar-assisted ejector-compressor hybrid refrigeration system with subcooling storage coupled at intermediate temperatures. The system model is established, and the ejector model is experimentally validated. Through system modelling, an energetic and exergetic performance comparative analyses are conducted. The results indicate that the COP of the proposed system is 9.7% higher than that of traditional system combinations, producing the same cooling capacity with the same generating heat. Moreover, considering the stored cooling energy can be fully converted to cooling energy at evaporating temperatures, the COPh of the new system reaches 8.29, 24.5% higher than traditional systems. The cooling storage at 15°C with 0.325 ejector entrainment ratio suggests a reduction of approximately two-thirds in energy storage, lower temperature differences, and reduced thermal leakage, leading to decreased space and economic costs and improved energy performance. Additionally, as the COPh, COPgh, and η ex of MCS mode consistently outperform those of ZCS and HCS modes, the MCS mode is prioritized in system operation. This study underscores that the new system offers superior overall energy efficiency and requires smaller storage devices compared to traditional systems, revealing its promising practical applications. [ABSTRACT FROM AUTHOR]

Cooling water systems (CWSs) are extensively utilized in various industries to eliminate the excess heat and converse energy. Studies on CWSs mainly concentrated on finding the optimal cooler network structure. In addition, some works also considered the optimal design under varied operation conditions. However, in these works, once the optimal design of the cooler's network is determined, its arrangement remains fixed and cannot be adapted to accommodate diverse operating conditions. In this work, a flexible topology network concept is proposed to make the adjustment of network structure possible under different operation conditions. The CWS with integrated air cooler and flexible topology network has better overall performance, represented by a mixed integer nonlinear programming (MINLP) model that require advanced tools such as GAMS software. Case studies revealed that the proposed methodology can realize better energy-saving performance, and improve the economic performance under varied operation conditions. The impact of critical flexible nodes on system configuration and economy is achieved by sensitivity analysis. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing (WAAM) is a notable process in metal additive manufacturing (MAM) for the fabrication of metal parts that utilizes economically viable equipment and has high productivity compared to other MAM processes. However, excessive heat accumulation during metal deposition and the cooling method can induce residual tensile stresses and the emergence of defects, which can compromise the geometrical and mechanical integrity of components produced by WAAM. A relatively effective solution to reduce the occurrence of defects and increase the production of high-quality, structurally reliable parts with better surface finishes is to implement temperature control between passes in the WAAM process. This work is aimed at implementing and evaluating active cooling techniques using forced air cooling system (FACS) and half-immersion cooling system (HICS) in WAAM. For this purpose, FACS and HICS systems were implemented and WAAM preforms were produced under different cooling conditions. Visual inspection and geometric and microhardness characterization of the obtained preforms were performed, as well as productivity analysis of the system. The results of the geometric evaluation show little discrepancy between the dimensions of the preforms produced with different cooling techniques, with significant reductions in manufacturing time using FACS and HICS compared to natural cooling (NC), by approximately 73.1% and 87.1%, respectively. Similarly, the impact of the cooling mode on the formation of porosities is discernible. When the FACS system is employed, these defects are more susceptible to generation. The transverse hardness profiles of the three preforms exhibited comparable trends along the manufacturing direction. However, the manufactured system used by HICS exhibited higher average hardness values. [ABSTRACT FROM AUTHOR]

Heating or cooling systems are of high demand in many industries. Both types of systems are dependent on the geometry. We characterized the CuO-water nanofluid flow, heat and mass transfer through a horizontal channel when additionally heated through the center. The heat is transferred from the cylinder present along the flow. The velocity slip, thermal and diffusion slip effects on the cylinder are studied. The transverse magnetic field is also applied. The Galerkin finite element method is applied to solve the coupled nonlinear governing equations. The results are presented using stream plots and contour plots. The rate of heat transfer is calculated.30% increase in heat transfer rate is observed when the thermophoresis is doubled. Interestingly heat transfer rate is reduced by 40% when the thermal slip is doubled. So the thermal slip is more useful to include in heating or cooling systems as per the industrial need. [ABSTRACT FROM AUTHOR]

Due to its improved capacity compared to graphite, silicon is a promising candidate to handle the demands of high-energy batteries. With the introduction of new materials, further aspects of the battery system must be reconsidered. One of those aspects is the heat generation during the charging and discharging of a cell, which delivers important information for the development of cooling systems, the battery management system and the overall performance of the cell. Since the reversible heat presents an important contribution to the overall heat generation during cycling, the entropy coefficient is the main value that needs to be determined. This study evaluates the entropy coefficient of custom-produced 2032 coin half-cells with lithium counter electrodes, containing 45 wt% nanosilicon and 45 wt% carbon black. The potentiometric method, utilizing VR and self-discharge curves, produced reliable results, yielding entropy coefficient values between 95% SoC and 10% SoC during delithiation. These values of the entropy coefficient are consistently negative. Furthermore, ICA measurements identified two phase transitions during delithiation, with these transitions shifting to lower SoC as SoH decreases, impacting the slope of the entropy coefficient. [ABSTRACT FROM AUTHOR]

Demand is high for small, lightweight, and power-dense machines. However, as power increases and size decreases, rejecting losses becomes more difficult. Many novel cooling systems have been developed, which have allowed machines to be made smaller while increasing power. This paper proposes a cooling system making use of soft magnetic composite (SMC) cores to improve cooling specifically in a high-speed axial-flux machine via the use of an integrated cooling channel in the SMC core. A series of experiments on a prototype machine are performed and the experimental data are used to determine a set of parameters for the FEA thermal model. Using the thermal FEA model, a comparison is completed with a traditional closed cooling system using laminated steels and an attached cooling plate.The SMC machine is then simulated at speeds up to 160 krpm and currents up to 8 A. To achieve the same coil temperature between the two designs, the laminated steel model required 4 MPa contact pressure at 10 krpm and 5 MPa contact pressure at 20 krpm. At the same time, the novel design removed approximately 20% more heat per shear air gap surface area and approximately 15% more heat per total machine surface area than the version with the attached cooling plate. Extending the operating range of the model to 160 krpm demonstrated that the maximum temperature rise remained below 180 °C. [ABSTRACT FROM AUTHOR]

Elastocaloric cooling is recognized as a promising alternative to modern vapor-compression cooling systems, which often rely on environmentally hazardous refrigerants. Natural rubber (NR), a well-known renewable resource, stands out among elastomers exhibiting elastocaloric behavior due to a peculiar combination of nontoxicity, low cost, softness, long-life fatigue and high caloric power. Despite these properties, research on the refrigeration potential of NR is still in its early stages, and several aspects require attention. This work investigates, for the first time, the effect of crosslinking density on the elastocaloric properties of NR. Samples with three different crosslinking densities (2.9, 4.0 and 5.2 mol·10−4/cm3) were produced by internal compounding and hot pressing, and thermo-mechanically characterized. The assessment of the elastocaloric effect of the produced samples revealed that reducing the crosslinking degree significantly enhanced the elastocaloric properties. To compare the cooling capacity of the samples, a qualitative coefficient of performance (COPmat) was evaluated as the ratio between extracted thermal energy and deformational work per unit volume. The results highlight that the least crosslinked sample achieved the higher COPmat, equal to 2.4. These results underscore the significance of crosslinking density as one of the primary factors to be considered to enhance the refrigeration potential of NR. [ABSTRACT FROM AUTHOR]

With buildings representing a substantial portion of global energy consumption, exploring alternatives to traditional fossil fuel-based heating and cooling systems is critical. Thermoelectricity offers a promising solution by converting temperature differentials into electrical voltage or vice versa, enabling efficient indoor thermal regulation. This paper presents a comprehensive investigation into the integration of thermoelectric wall systems for sustainable building climate control through numerical simulations and experimental analyses. Numerical simulations using computational fluid dynamics (CFD) techniques were conducted to model fluid flow and heat transfer within the thermoelectric wall systems under various operating conditions. These simulations provided insights into the system's thermal behavior, which were validated through experimental setups designed to measure temperature differentials, airflow rates, and power consumption. The results showed that power consumption is directly correlated with electrical current, ranging from 0.19 W to 77.4 W as the current increased from 0.1 A to 2 A. Additionally, the heat absorbed by the system increased significantly with electrical current, by 706–1044%, depending on the air velocity. The thermal energy released from the hot side of the thermoelectric modules also rose substantially, ranging from 9850 to 5285% with increasing electrical current, and from 275 to 51% with higher air velocities. Moreover, increasing air velocity led to a 6.78–9.37% reduction in power consumption for currents between 0.1 A and 2 A. The coefficient of performance (COP) analysis revealed that optimizing both electrical current and air velocity is essential for maximizing system efficiency. While fan power consumption reduces COP at higher air velocities, neglecting fan power consumption results in COP improvements ranging from 6.5 × 10⁻⁴ to 49.0%. These findings highlight the potential of thermoelectric wall systems to enhance indoor comfort and energy efficiency in buildings. [ABSTRACT FROM AUTHOR]

Thermoelectric technology has witnessed a resurgence in recent years due to increasing demands for sustainable energy sources and efficient cooling systems. Recently, the introduction of Te‐free thermoelectric modules using non‐toxic, abundant materials including p‐type MgAgSb and n‐type Mg3(Sb,Bi)2 marked a significant breakthrough. Despite promising performance, questions persist regarding long‐term robustness and stability, especially in harsh environments. In this study, a thorough exploration of thermoelectric modules is conducted, focusing on their performance degradation under various conditions. Through elemental mapping analysis, degradation mechanisms are identified within the modules during cycling in argon environments, where atomic migrations and the formation of complex oxides at contact regions are key factors. Furthermore, cycling tests in air reveal significant degradation, prompting the exploration of protective strategies. Surface coatings using atomic layer deposition (ALD) emerge as a promising solution, particularly by HfO2, demonstrating superior protective effects. Furthermore, re‐soldering effectively restores module performance is found, highlighting the importance of developing advanced soldering techniques to promote magnesium‐based thermoelectric technology as a sustainable alternative to Bi2Te3. These findings emphasize the importance of exploring novel contact materials and demonstrate the potential of ALD as a universal approach to enhancing module reliability and robustness. [ABSTRACT FROM AUTHOR]

A novel heat-driven ejector refrigeration machine for an onboard air-conditioning system of a merchant ship was conceptualized and analyzed. The source of waste heat is low-pressure steam from the exhaust gas boiler (0.5-0.7 MPa). However, the steam from auxiliary boilers is used in port. It was proposed to include a thermal energy storage unit in the ejector refrigeration machine design to reduce fuel consumption by auxiliary boilers in the port. A phase change material with a melting point of 142 °C was proposed for use as thermal energy storage material. It was admitted for the TES unit to replace half of the generator load for 1 day of operation. For such conditions the volume and mass of the thermal energy storage unit were 16.5 tons and 125 m3 at an ejector refrigeration machine cooling capacity of 174 kW. It was shown that ejector refrigeration machine with thermal energy storage unit inherent the lower fuel consumption for its operation compared to the vapor-compression refrigeration machine: 53916 vs. 80567 kg of fuel per year. It is advisable to use the proposed ejector refrigeration machine with a thermal energy storage unit on ships that have short voyages and frequent stays in port. The problems in the TES unit design that need to be studied further have been noted in the paper. [ABSTRACT FROM AUTHOR]

Decarbonising heating and cooling systems, significant contributors to the EU's (European Union) energy consumption, is a complex and urgent matter. This article discusses the potential coupling of energy communities and district heating and cooling systems, particularly fourth‐ and fifth‐generation models, in the local energy transition. The integration of new‐generation district heating and cooling systems into renewable energy generation is crucial for sustainability, circular economy practices, and community‐based solutions. An examination of the EU legal framework within the Fit‐for‐55 package elucidates how provisions from the new Energy Efficiency Directive and Renewable Energy Directive facilitate the implementation of energy communities in the heating and cooling sector. The existing enabling legislation underscores the suitability of energy communities for heating and cooling sector activities, acknowledging their transformative potential in advancing the energy transition and fostering community empowerment. [ABSTRACT FROM AUTHOR]

The paper introduces a novel method for generalized heat exchanger (HX) design and evaluation, freeing the process from predefined geometries. It aims to facilitate early-stage conceptual exploration, allowing the designer to make informed decisions. The paper explores heat transfer and fluid friction principles in order to set key parameters for estimating aerothermal performance, introduced by LaHaye et al. Arguing against a single metric, the paper proposes a custom cost function (CF) for evaluating the integrated generalized heat exchanger. A case study applies the method to a particular aircraft engine scenario, using cost functions to evaluate intercooler designs based on pressure loss and heat transfer surface weight. The study determines suitable heat exchanger families for further development, considering factors like finned area, compactness, and flow distribution. [ABSTRACT FROM AUTHOR]

The plastic injection moulding industry is a constantly developing industrial field. This industrial process requires the manufacturing of metal moulds using complex heating and cooling systems. The purpose of this research is to optimize both the plastic injection moulding process and the mould manufacturing process itself by combining practices in this industry with current additive manufacturing technologies, specifically Wire Arc Additive Manufacturing (WAAM) technology. A mould punch was manufactured by using both WAAM technology, whose internal cooling system has been designed under the concept of Conformal Cooling, and conventional cooling channel designs and manufacturing techniques in order to carry out a comparative analysis. Theoretical results obtained by CAE methods showed an improvement in heat extraction in the WAAM mould. In addition, the WAAM mould was able to achieve better temperature homogeneity in the final part, minimizing deformations in the final part after extraction. Finally, the WAAM manufacturing process was proven to be more efficient in terms of material consumption than the conventional mould, reducing the buy-to-fly ratio of the part by 5.11. [ABSTRACT FROM AUTHOR]

The upgrade of the Swiss Light Source, called SLS 2.0, necessitates comprehensive updates to all 18 user front ends. This upgrade is driven by the increased power of the synchrotron beam, reduced floor space, changing source points, new safety regulations and enhanced beam properties, including a brightness increase by up to a factor of 40. While some existing front‐end components are being thoroughly refurbished and upgraded for safety reasons, other components, especially those designed to tailor the new synchrotron beam, are being completely rebuilt. These new designs feature innovative and enhanced cooling systems to manage the high‐power load and meet new requirements such as mechanical stability and compact footprints. [ABSTRACT FROM AUTHOR]

COSINUS will be among the first underground experiments to operate Transition Edge Sensors in a dry dilution refrigerator, measuring temperature changes on the order of μ K. A pulse tube cryocooler is used to cool down to 3K, trading simplified handling, by not using liquid noble gases, for an increased vibration noise level in the acoustic frequency range. As the signals measured with a TES are in the same frequency region, it is necessary to decouple the detectors from all possible noise sources. In COSINUS, a two-level passive decoupling system was developed and tested using piezo-based accelerometers. At the first level, the refrigerator is mechanically isolated from all external noise sources. For the second level an internal spring-based system was developed and tested on a mockup system. On the first level a reduction of the vibrational background up to a factor 4 below 10 Hz could be measured. On the second level a resonance frequency of 1.2 Hz with damping of higher frequencies was achieved. [ABSTRACT FROM AUTHOR]

Two-phase flow is widely used in the cooling system of electronic equipment, where the heat source is localized. However, two-phase flow may lead to flow instabilities, which have adverse effects on the system such as heat transfer deterioration and vibration. In this study, the effects of related variables on Ledinegg instability in single and parallel channels under localized heat source are investigated. Both models of single and parallel channels have been verified, and the maximum relative error is within ±5%. Based on these two models, the results indicate that the high heating power and low inlet subcooling promote Ledinegg instability, whereas Ledinegg instability is independent of the channel inclination. The average negative slope of continuous heat source, −0.09557, is smaller than that of the heat source close to inlet, −0.07408, which shows the improvement of localized heat source on Ledinegg instability. For the parallel system, when the flow excursion occurs, the total mass flow rate, which is 0.028 kg/s, is equal to two times of the mass flow rate of maximum value in branch pressure curve at which pressure is equal to 0.778 MPa, if two branches are identical. The current work provides qualitative conclusions on how Ledinegg instability will be affected with the change of relevant variables. [ABSTRACT FROM AUTHOR]

A digital twin-driven lifecycle management method is proposed to monitor the lifespan of motorized spindle. The lifecycle management system is designed and developed based on the combined programming of MATLAB, ANSYS, and LabVIEW. The prediction models of lifespan are built according to the digital twin (DT) data of thermal characteristics of the motorized spindle. The DT for thermal characteristics is realized through correcting the thermal boundary conditions according to the correction models which are established according to the measured and simulated temperatures at thermal key points. The temperature domain and threshold models of the cooling channel are constructed using the exponential fitting method to monitor the working status of the cooling system. The experimental results show that the DT-driven lifecycle management system can effectively monitor the status and remaining useful life of the motorized spindle, which provides a basis for the lifecycle management of the motorized spindle. [ABSTRACT FROM AUTHOR]

This paper investigates the hydrothermal behavior of leaky dielectric and perfect dielectric droplets impacting a superheated wall within a specific range of Weber numbers (We≤30) $(We\le 30)$ under an electric field. Through this investigation, we aim to provide a more comprehensive understanding of the dynamics involved in droplet‐superheated surface interactions under electric fields, which can be useful in various applications, such as the design of cooling systems and combustion chambers. The study utilizes the level‐set and ghost fluid techniques to capture the interface accurately. Under an electric field, different behaviors are observed during the impact process, depending on the electrical properties of the droplet. A perfect dielectric droplet experiences a reduction in spreading extent and an increase in contact time. However, no remarkable enhancement in total heat removal occurs in this case. For the leaky dielectric droplet exhibiting prolate deformation at the stationary state, increasing the electric field magnitude results in a slight decrease in the droplet spreading extent, while the droplet contact time and total heat removal from the surface increase. At an electric capillary number of 1.55E − 2 and a Weber number of 25, the enhancement in the contact time and total heat removal is about 43% and 15%, respectively. For the leaky dielectric droplet with oblate deformation at the stationary state, the spreading extent and total heat removal increase, with negligible changes in contact time. At the above‐mentioned electric capillary and Weber numbers, the enhancement in the spreading extent and total heat removal is about 7.5% and 15%, respectively. [ABSTRACT FROM AUTHOR]

For a photovoltaic module coupled with thermoelectric generator, a unique wavy cooling channel is proposed, and its performance is numerically assessed by using three-dimensional computations. The cooling channel uses nanofluid of alumina–water with various shaped nanoparticles (spherical, cylindrical and brick). Numerical simulations are performed for a range of parameters for the corrugation amplitude ( 0 ≤ Amp ≤ 0.1 ), wave frequency ( 2 ≤ Nf ≤ 16 ), nanoparticle loading quantity ( 0 ≤ SVF ≤ 0.03 ), and nanoparticle shape (spherical, brick, and cylindrical). We analyze the photovoltaic module's average temperature and temperature uniformity for a variety of parameter variations. When nanofluid and greater channel corrugation amplitudes are utilized, the average panel surface temperature is decreased more. A wavy shape of the cooling channel at the maximum corrugation amplitude yields a cell temperature reduction of 1.88 o C, while frequency has little impact on average cell temperature and its uniformity. The best-performing particles are those with cylindrical shapes, and the drop-in average photovoltaic temperature with solid volume fraction is essentially linear. As utilizing cylindrical-shaped particles, the average temperature of corrugated cooling channels decreases by around 1.9 o C as compared to flat cooling channels with base fluid at the greatest solid volume fraction. As compared to un-cooled photovoltaic, cell temperature drops by around 43.2 o C when employing thermoelectric generator. However, temperature drop value of 59.8 o C can be obtained by using thermoelectric generator and nano-enhanced wavy cooling channel utilizing cylindrical-shaped nanoparticles. An hybrid computational strategy for the fully coupled system of photovoltaic with cooling system is provided, which reduces the computational time by a factor of 75. [ABSTRACT FROM AUTHOR]

The design integration of absorption and adsorption cooling systems is a recently emerging research field in which the inherent advantages of both these systems are intended to be combined so as to maximize system performance. However, a vast majority of the conventional integration approaches reported in the literature still suffer from the following drawbacks: (a) the inability to provide a continuous cooling effect of the integrated design during the switching period of the adsorption component, (b) the lack of incorporation of the mass/heat recovery cycles and its subsequent effects upon the integrated performance, and (c) the lack of functional dependence of all thermodynamic variables including heat capacities and adsorption enthalpy upon operational parameters such as temperature and pressure. This study presents the first attempt of a numerically validated performance prediction of such an integrated system with parallel functionality to facilitate a continuous cooling operation. An empirical model of mass recovery cycle has been formulated for the very first time which adequately describes the sorption dynamics during mass transfer. All thermodynamic variables have been expressed as functions of operational parameters during the cooling cycle. For a mean driving temperature predicted to be as low as 38 °C and a mean cycle time of 11.82 min, the proposed integrated design has been predicted to yield a cycle-averaged specific cooling power of 48.93 W kg−1 and a minimum achievable coefficient of performance of 0.74 compared to the corresponding values of 27.64 W kg−1 and 0.57 for the benchmark stand-alone silica gel/water adsorption chiller. [ABSTRACT FROM AUTHOR]

Purpose: Steam explosions are a major safety concern in many modern furnaces. The explosions are sometimes caused by water ingress into the furnace from leaks in its high-pressure (HP) cooling water system, coming into contact with molten matte. To address such safety issues related to steam explosions, risk based inspection (RBI) is suggested in this paper. RBI is presently one of the best-practice methodologies to provide an inspection schedule and ensure the mechanical integrity of pressure vessels. The application of RBIs on furnace HP cooling systems in this work is performed by incorporating the proportional hazards model (PHM) with the RBI approach; the PHM uses real-time condition data to allow dynamic decision-making on inspection and maintenance planning. Design/methodology/approach: To accomplish this, a case study is presented that applies an HP cooling system data with moisture and cumulated feed rate as covariates or condition indicators to compute the probability of failure and the consequence of failure (CoF), which is modelled based on the boiling liquid-expanding vapour explosion (BLEVE) theory. Findings: The benefit of this approach is that the risk assessment introduces real-time condition data in addition to time-based failure information to allow improved dynamic decision-making for inspection and maintenance planning of the HP cooling system. The work presented here comprises the application of the newly proposed methodology in the context of pressure vessels, considering the important challenge of possible explosion accidents due to BLEVE as the CoF calculations. Research limitations/implications: This paper however aims to optimise the inspection schedule on the HP cooling system, by incorporating PHM into the RBI methodology, as was recently proposed in the literature by Lelo et al. (2022). Moisture and cumulated feed rate are used as covariate. At the end, risk mitigation policy is suggested. Originality/value: In this paper, the proposed methodology yields a dynamically calculated quantified risk, which emphasised the imperative for mitigating the risk, as well as presents a number of mitigation options, to quantifiably affect such mitigation. [ABSTRACT FROM AUTHOR]

An intermittent spray cooling system is applied to fuel cell vehicle heat dissipation using a plate-fin heat exchanger. The effects of various system parameters on cooling performances are evaluated. Experimental results indicate that the cooling performance can be increased by 20% to 80% at various operating conditions and fixed spray area percentage of 45%. An empirical correlation is constructed to characterize heat transfer enhancement percentage. For the 124 data points examined, 92.73% of the data are within 20% of the error range, and 81.8% are within 15% of the error range. The average absolute deviation is 9.30%. [ABSTRACT FROM AUTHOR]

Evaporative cooling systems have gained increasing attention as an energy-efficient solution for climate control in hot and dry regions. This review aims to assess the effectiveness of the most recent advancements in evaporative cooling technologies for building applications in hot and dry climates. The review focuses on global literature, with an emphasis on building applications. The findings of this review indicate that evaporative cooling systems with hybrid configurations, particularly multi-stage systems, can achieve cooling efficiencies of up to 95%. These systems are highly energy-efficient, with energy consumption ranging from 0.3 to 1.2 kW/t, with hybrid and multi-stage designs showing the best performance. Direct and indirect evaporative cooling systems also perform well, with cooling effectiveness ranging from 60% to 85%. Their reliance on water, rather than harmful refrigerants, results in minimal environmental impact, making them an eco-friendly alternative to traditional cooling methods. The coefficient of performance (COP) for these systems is favorable, with hybrid and multi-stage designs reaching COP values as high as 35, indicating substantial cooling output relative to energy input. In addition, the performance of evaporative cooling systems is highly influenced by their design parameters and operating conditions. Advanced designs that incorporate multi-stage cooling and effective water management tend to provide enhanced cooling capacity and energy efficiency. Therefore, evaporative cooling systems are an excellent option for sustainable building practices, contributing significantly to energy savings and reduced environmental impact. [ABSTRACT FROM AUTHOR]

Bamboo, particularly Guadua Angustifolia cane, offers significant thermal benefits for construction in warm, humid climates and has been a key material in Ecuador for over 9500 years due to its low cost, versatility, and low thermal conductivity. In the coastal region, including the settlement of El Carmen, traditional architectural techniques have evolved to incorporate local materials like Guadua cane. A common method involves using crushed cane as wall cladding, where longitudinally split bamboo is applied, creating openings in the structure. These openings, often viewed as a construction defect, influence passive cooling systems. This study investigated the impact of these irregularities on indoor thermal comfort by documenting the construction systems and climatic conditions of the area. Computational models were reconstructed and tested through CFD simulations to assess thermal behavior. The findings highlight the thermal implications of the vernacular construction system, revealing how wall openings affect passive cooling strategies and overall indoor comfort in the housing typologies of El Carmen. [ABSTRACT FROM AUTHOR]

Radiant cooling systems are widely valued for their great comfort and energy-saving potential. However, they still face the risk of condensation in the early stages of operation, especially in case of random occupancy and intermittent operation. This study aims to avoid unacceptable discomfort durations in randomly occupied rooms that installed integrated radiant cooling and fresh air system while consuming as little energy as possible. This paper firstly compares the effects of adopting only the setback or standby cooling strategy in a randomly occupied conference room by simulation. The simulation results demonstrate the necessity for predicting optimal operation strategy. Subsequently, optimal operation strategy predictive models were built using three machine learning algorithms on three datasets. The evaluation results of the models indicate the feasibility of using data from neighbouring cities to improve the generalisation ability of the target city model. Finally, the best one of models was used to predict optimal operation strategy and achieved good results: discomfort durations of 97.56% of the conferences were within the acceptable range. Additionally, compared to only adopting the standby cooling strategy, the radiant cooling system operating time was reduced by 8.88%, and the total energy consumption was reduced by 28.85 kWh. Practical application : In this study, a model to predict optimal operation strategy is proposed. By simulating and analysing from both comfort and energy perspectives, the optimal operation strategy predictive control method effectively limits the discomfort duration and reduces energy consumption and radiant system runtime. This study provides an example of practical engineering and machine learning applications for radiant cooling systems. [ABSTRACT FROM AUTHOR]

District Cooling Systems are progressively becoming a standard feature of smart cities. This is attributed to their inherent feature of low operating cost and high energy efficiency. Given the constantly increasing energy prices worldwide and the target of the Conference of the Parties-28th Session for reducing emissions, the District Cooling System technology is quite promising in this direction. Various studies are available that have particularly focused on the design phase optimization of the systems, while in-process operational optimization is still in its miniature phase. This paper presents a model-based metaheuristic optimization approach to cooling water system towards an inceptive control strategy to explore and exploit the energy-saving potential using a Real Coded Genetic Algorithm. The Algorithm is implemented in MATLAB to search for high-performance settings in real-time scenarios. The results showed that an energy saving from 9.66% to 26.54% can be obtained across 6 cases in the study, compared to the supervisory control. Practical application: District cooling technology is expected to gain more credibility as the most sustainable alternative to air conditioning in the upcoming decades due to the world's rapidly expanding need for cooling combined with the need to reduce carbon dioxide emissions. The current research and development efforts are yielding promising results for the fifth generation of this technology. Meanwhile, the study validates the enormous potential of operational optimization with contemporary artificial intelligence tools. This paper paves the way for future research by showing how the operation of a large-scale district cooling plant can be solved for energy saving. [ABSTRACT FROM AUTHOR]

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A model of the dynamics of soluble salts in the water of cooling systems of circulating water supply was developed based on mass balance principles. The proposed model is expressed in a general form under the assumption of a constant volume of circulating water and non-stationary input and output flows. The model accounts for scenarios where the concentration of soluble salts exceeds their concentration in the circulating water, thereby considering the technological necessity to change the system’s power source in the event of an emergency at the feedwater treatment facilities. The developed model enables accurate prediction of the water-chemical regime in both existing and new recirculating cooling systems, sufficient for engineering calculations. It also facilitates the selection of optimal management strategies for such systems, including stabilization methods for recirculating water, feedwater preparation, blowdown volumes, etc. The model was validated under laboratory conditions for cases of concentration and dilution of highly soluble NaCl salt, with an observed error margin not exceeding ±2%, attributed to experimental and instrumental factors. The variation in the concentration factor was analyzed for different blowdown rates, assuming initial equality of soluble salt concentrations in feedwater and circulation water. It was shown that establishing dynamic equilibrium between the circulation and feed waters can require dozens or even hundreds of circulation cycles for blowdown rates of 1–4%, and this system inertia must be considered during operation and when forecasting the performance of cooling systems with circulating water supply. [ABSTRACT FROM AUTHOR]

Carbon capture and storage can reduce the carbon emission directly and effectively. Absorption carbon capture (ACC) is currently the most promising way to remove CO2 from coal-fired power plant, yet the main drawback is the excessive thermal energy consumption for the regeneration process. In this study, a new ACC system that utilizing the low-grade waste heat to generate steam has been proposed, in which system the steam is compressed to increase the saturation temperature to satisfy the thermal energy grade demand of the absorbent regeneration. Heat pump is introduced to increase the inlet pressure and enhance the energy and economic effect of vapor compression and R245fa is found suitable for the system. The vapor generating work can be controlled below 200 kWh t−1 when Twh is higher than 60°C, and COPvg can be higher than 3.5 for situations of Ttag,sat not exceeding 130°C. The energy performance and economic analysis of the proposed ACC system driven by the new vapor generation method is analyzed. Off-peak operation by ASS shows good economic effect, the operating cost for the regeneration process of carbon capture is only 69.70 CNY t−1 CO2 under the worst condition and far below the traditional heating method. The new heat supply method for carbon capture presents reasonable energy and economic performance, which is shown suitable for peak shifting of the power grid. [ABSTRACT FROM AUTHOR]

The study of magnetohydrodynamics (MHD) and thermal radiation over‐stretching and shrinking sheets has significant applications in a wide range of fields, from chemical manufacturing to transport engine cooling systems, electronic chip cooling, plasma, the nuclear‐powered sector, saltwater, etc. The present study aims to numerically and theoretically analyze the movement of thermally magnetized Williamson nanofluid owing to an extended/contracting sheet. The regulating flow equations are converted to self‐similar equations through similarity transformation, and then numerically solved by bvp4c using MATLAB software. A comparison of the present numerical study with the published study is quite impressive. The investigation demonstrates that the self‐similar equations disclose the two branches for the limited shrinking factor range. For the stretching case, only one solution exists. As a result, the most fundamentally feasible solution has been determined by the linear assessment of temporal stability. For the aim of stability analysis, the lowest eigenvalue sign indicates the stability or instability of a solution. Through stability analysis, it is witnessed that the first solution (first branch) is stable. Due to the presence of the Lorentz force effect, it is perceived that the velocity curves decline in the whole channel. The point to be noted here is that the velocity of the lower branch compared to the upper branch is higher. The reduced Skin Friction is increased in the first branch and declines in the second branch for the two different values of magnetic factor. [ABSTRACT FROM AUTHOR]

Soft robots have excellent spatial adaptability and high flexibility, but they are limited by the low stiffness of their constituent materials when faced with high‐load tasks. In recent years, there have been many works on the development of stiffness‐tunable soft actuators by introducing variable stiffness materials into soft actuators, but the existing solutions usually suffer from the problems of slow response, complex structure, and the need of many auxiliary devices to support the completion of the stiffness tuning cycle. This paper proposes a tendon‐driven stiffness‐tunable soft actuator that addresses these issues. Benefiting from the bidirectional temperature control of thermoelectric modules and the excellent in‐plane thermal conductivity of graphene, the actuator is capable of achieving the heating and cooling process by transferring the heat flow through the graphene structure into and out of the shape‐memory polymer (SMP) layer of the tendon‐driven actuator. This enables stiffness tuning via a single device, reducing the dependence on complex external cooling systems. The use of tendon‐driven actuators further eliminates the complex bellow structure of conventional pneumatic actuators and dramatically reduces the size and manufacturing difficulty of individual actuators. Finally, the high load capacity and shape adaptability of the actuator are demonstrated by a gripper equipped with three actuators, which successfully grips objects of various shapes and weights, ranging from less than 10 g to up to 1.6 kg. [ABSTRACT FROM AUTHOR]

The conformal cooling channel is more and more favored by the mold enterprises because of its excellent cooling performance. However, the current design of conformal cooling channel generally has the problems of complex, time-consuming, and error prone design process. The spiral cooling channel is a very important cooling channel structure in injection mold, and its application is extremely common in practical mold engineering cases. For a long time, designers have had to rely on manual construction of spiral cooling channel, which is a cumbersome and inefficient design process. Inspired by the spring structure and based on the design characteristics of spiral cooling channel, this paper puts forward an automatic generation method of conformal cooling channel based on the basic requirements of conformal cooling channel design in engineering practice. The basic idea of this method firstly is to generate the initial trajectory lines and store them in a list in the specified order. Then, based on the initial trajectory line as the basic geometry, a series of control points are generated, and all control points, including the inlet and outlet coordinate points, are sorted. Finally, generate a spline curve based on the control points and scan along the spline curve with the specified cross-section to form cooling channels. Experimental results show that this method can significantly decrease the time of design and guide users to quickly complete the design, while reducing design errors to improve working efficiency. [ABSTRACT FROM AUTHOR]

Sub‐ambient cooling technologies relying on passive radiation have garnered escalating research attention owing to the challenges posed by global warming and substantial energy consumption inherent in active cooling systems. However, achieving highly efficient radiative cooling devices capable of effective heat dissipation remains a challenge. Herein, by synergic optimization of the micro‐pyramid surface structures and 2D hexagonal boron nitride nanoplates (h‐BNNs) scattering fillers, pyramid textured photonic films with remarkable solar reflectivity of 98.5% and a mid‐infrared (MIR) emittance of 97.2% are presented. The h‐BNNs scattering filler with high thermal conductivity contributed to the enhanced through‐plane thermal conductivity up to 0.496 W m−1 K−1 and the in‐plane thermal conductivity of 3.175 W m−1 K−1. The photonic films exhibit an optimized effective radiative cooling power of 201.2 W m−2 at 40 °C under a solar irradiance of 900 W m−2 and a daily sub‐ambient cooling effect up to 11 °C. Even with simultaneous internal heat generation by a 10 W ceramic heater and external solar irradiance of 500 W m−2, a sub‐ambient cooling of 5 °C can be realized. The synergic matching strategy of high thermal conductivity scattering fillers and microstructured photonic surfaces holds promise for scalable sub‐ambient radiative cooling technologies. [ABSTRACT FROM AUTHOR]

Mean radiant temperature (MRT), which is a crucial factor for thermal comfort, varies within a space. This renders deriving the representative values for radiant heating and cooling control challenging. This study reviewed existing methods for deriving MRT in previous research and addressed their limitations by proposing a method for determining a representative MRT value. The existing methods were categorized as air temperature, single location, and area weighted. Three methods for deriving representative MRT values were proposed, considering the building's usage, scale, and applicable system installations. The proposed methods were categorized as single-zone averaged, multi-zone averaged, and point-zone MRT. Experiments were conducted by distinguishing cases based on the control of equipment systems during heating and cooling periods. During the cooling season, the single-zone averaged MRT and air temperature differed by up to 4 °C, and the difference between the multi-zone averaged MRT and MRT at a point in the perimeter zone reached up to 7 °C. During the heating season, the single-zone averaged MRT and air temperature differed by up to 2.2 °C. Thus, the results of this study emphasize the importance of applying different methods of deriving representative MRT values depending on the size and usage of the building, and demonstrate that this facilitated more effective heating and cooling control systems. [ABSTRACT FROM AUTHOR]

This paper presents the application of the multiple-criteria decision-making (SAW) method for selecting the optimum refrigerant for the refrigeration systems of commercial cooling equipment used in gastronomy furniture, which is paramount in storing food under optimal conditions. The analysis focused on comparing different refrigerants, including natural refrigerants such as R744 (carbon dioxide) and R290 (propane) and synthetic refrigerants such as R455A, R449A, and R452A. As a result of the analysis using the SAW method, the refrigerant R455A was found to be the best solution. This choice resulted from the consideration of various decision criteria, such as energy efficiency, environmental impact, operating costs, and technology availability. R455A stands out as a synthetic refrigerant that provides high energy efficiency with minimal environmental impact. Its use supports sustainability goals by reducing greenhouse gas emissions and electricity consumption, which is crucial given the modern regulatory requirements and environmental standards. This study offers a practical decision-making tool for commercial refrigeration equipment designers and manufacturers, supporting them while selecting the optimal technological solutions. The choice of refrigerant R455A addresses the need to integrate energy efficiency, environmental protection, and cost-effectiveness in the process of designing modern refrigeration systems for catering furniture. [ABSTRACT FROM AUTHOR]

In large-format pouch cells for electric vehicles, the issues of elevated and non-uniform temperatures resulting from heat generation are intensified, necessitating the use of liquid cooling systems. The design factors of the liquid cooling system influence the maximum temperature and temperature differences in the module as well as the pumping power of the cooling system. Although it is known that these design factors interact, research on these interactions and their effects is currently lacking. In this study, the individual as well as interaction effects of design factors on the performance of the liquid cooling system for a large-format pouch cell module were investigated using design of experiment and analyzed through statistical methods. Electrochemical–thermal fluid coupled analysis was used to calculate the performance according to the design factors of the liquid cooling system. The wall and channel widths are factors that directly determine the coolant flow velocity and cooling plate heat capacity, and they exhibited major effects on all three responses. Moreover, the influence of each design factor tended to change in response to variations in the other design factors. Thus, the effects of each factor individually and of interactions between factors were quantitatively compared and evaluated for significance. The width of the walls was found to contribute the most to the maximum temperature (36.00%) and pumping power (57.56%), while the width of the channels contributed the most to the temperature difference (38.24%), indicating that they are the main influencing factors. [ABSTRACT FROM AUTHOR]

A study of an alternative ejector cooling system is proposed in this paper. A mathematical model without irreversibility is developed and simulated. The numerical results are validated with literature data for two working fluids (R134a and R152a). The performance and behavior of the system using conventional refrigerants (HFC's, HC's) and unconventional (R717, R718) is obtained; the process uses 100 kW of heat available in a waste stream. Finally, the paper explores the reduction of problems associated with the use of conventional refrigerants by introducing the use of R718 (water) as the working fluid of the proposed system. [ABSTRACT FROM AUTHOR]

A thermoelectric cooling and thermal control system for electronic devices is considered. Based on a mathematical model using the operating characteristics of a serial thermoelectric module as the initial data, the energy characteristics of a thermoelectric cooling system are calculated, taking into account its thermal resistances. The calculation results are presented in the form of diagrams, which allow for a coordinated selection of the system's thermal resistances, ensuring the specified values of the cooling capacity and temperature difference. [ABSTRACT FROM AUTHOR]

This study examines the efficiency of a microprocessor's cooling system and maintaining the optimal temperature of electronic components. To do this, experiments are carried out on the existing cooling system of the microprocessor with control of all main parameters, primarily such as the temperature and coolant flow, as well as the performance and temperature of the processor. Based on the data obtained, a mathematical model is built that describes the change in the microprocessor's power and allows us to calculate the temperatures and speeds of coolants, as well as obtain the most effective modes for the operation of the cooling system. The obtained experimental data and mathematical model make it possible to predict the required power of the cooling system and the operating parameters of microelectronic components, which is especially important when new generations of microprocessors with the highest performance appear. The data obtained also makes it possible to calculate parameters for existing processors in order to maximize the efficiency and reliability of their operation, which is also relevant for other electronic devices, in particular microcontrollers. [ABSTRACT FROM AUTHOR]

Uncooled and shutterless microbolometer cameras are good candidates for infrared imaging systems installed on small satellites or small unmanned aerial vehicles: they are light and passive since no cooling system or mechanical shutter is required and they can be operated at ambient temperatures. However, the radiometric compensation has to be carefully performed to make the system compatible with applications where the radiometric accuracy of the images is mandatory. In this paper, we study the impact of the camera environment to the radiometric accuracy of the images. We propose and test hardware and software solutions to improve this accuracy and the quality of the radiometric images. We show that the radiometric calibration of the camera with our model is valid over a long time period— about 3 years—using in-door experiments. [ABSTRACT FROM AUTHOR]

This article explores the potential applications of elastocaloric materials, specifically shape memory alloys (SMAs), in the medical and biomedical industry. It discusses the principles and mechanisms of the elastocaloric effect in SMAs and highlights the performance indices and various SMA families. The article reviews recent developments in elastocaloric cooling devices and identifies several promising areas for biomedical applications. It emphasizes the importance of durability and fatigue resistance for biomedical devices and discusses the challenges and opportunities in integrating elastocaloric elements into biomedical devices. The article concludes by encouraging further research and development in this field to support the future development of biomedical solid-state refrigeration and heating technologies. [Extracted from the article]

• A small-scale pumpless absorption refrigeration (ARC) system is established. • Switching valves method (SVM) is employed to substitute for electrical pump. • Non-toxic R134a/DMF is chosen to create high pressure differential for pumping liquid. • The pumpless ARC system is validated feasible for low-grade thermal energy recovery. • The maximum COP of the system is 0.28. To address the challenges related to corrosion, sealing, additional electrical energy consumption, and the limited adaptability imposed by the electrically-driven solution pump to small-scale absorption refrigeration cycle (ARC) system, a pumpless module based on the switching valves method (SVM) is designed and constructed for an ARC system. The pumpless operation is realized based on thermal-gravity-driven mechanism by employing a corresponding valve-assembly among three vessels, which effectively substitutes for the electrical solution pump. R134a/DMF is employed as the working pair to maintain the necessary pressure differential for efficient solution pumping process. The overall performance of the system is studied. Experimental results show that the system operating parameters fluctuate periodically, and the fluctuation induces periodic variations in heat input and cooling capacity in the range of 0.95∼1.76 kW and 0.27∼0.79 kW, respectively. For the system the maximum cooling capacity of 0.79 kW and the average cooling capacity of 0.33 kW are achieved under the conditions of valve opening of 32°, average hot oil temperature of 116.9°C, heat sink temperature of 30.9°C, cooling source temperature of 25.9°C, and cycle time of 300 s, while the average COP of 0.28 is achieved at the cycle time of 420 s under the same conditions. The pumpless module is validated feasible as a promising alternative to solution pump, especially for small-scale system. [ABSTRACT FROM AUTHOR]

• A novel parameter is introduced to refine the refrigerant leakage theory. • The refrigerant leakage process carries a higher oil content is confirmed. • The effect of leakage mass flow rate on oil content is investigated. • The oil content is highest when refrigerant leaks from the high-pressure pipe. Refrigerant leakage is a situation that often occurs in refrigeration equipment such as heat pumps. However, certain alternative refrigerants, while exhibiting superior environmental performance, possess varying levels of flammability. The leakage of flammable refrigerants into confined spaces can pose a significant risk of explosion. The amount of lubricant in the leaking refrigerant will undoubtedly affect the flammability characteristics of the refrigerant. In this paper, the content of PVE32 oil in the leaking refrigerant during the operation of a heat pump was investigated. The results showed that, under the five leakage rate scenarios set up in the experiment, the oil concentration was highest when the leakage occurred at the condenser inlet and lowest when the leakage was at the evaporator outlet. During the leakage process of the experiment, as the mass flow rate of the leakage increased, the oil content in the early stage of the leakage increased, but the oil content in the late stage of the leakage decreased. The reasons for the change in oil content were analyzed by the oil circulation rate and the degree of phase separation. The decrease of the oil circulation rate and the change of the degree of phase separation were the key factors affecting the magnitude of the oil content as the leakage proceeded. The results of the study reveal the leakage characteristics of lubricating oil with refrigerant leakage. [ABSTRACT FROM AUTHOR]

The methods of increasing the efficiency of internal combustion engines through heat utilization are examined. A proposed classification of heat utilization systems for mobile energy vehicles is presented. External utilization harnesses the heat generated by a diesel engine to fulfill the needs of consumers not directly related to the engine, such as interior heating and air conditioning systems. Internal recycling focuses on enhancing the power, environmental performance, and economic performance of an engine and its related systems. Various heat utilization schemes are compared. For the economic conditions of the European Union (EU), a turbocompounding diesel engine is acceptable if its agricultural tractor rated power is more than 275 kW and its combine harvester rated power is more than 310 kW. Steam injection into the combustion chamber is utilized to improve the technical and economic performance of gas turbine engines. This technology is also produced in Ukraine and is proposed for use in internal combustion engines. It is suggested to inject water vapor into a turbocharger turbine. This approach reduces the number of components in the heat recovery system, thereby lowering its cost. A recycling chiller can be employed to cool the air after it passes through the air cleaner, enhance the efficiency of the air cooler, and improve the performance of the thermoelectric generators. This device is particularly effective at relatively high air temperatures and can be recommended for agricultural machinery that operates in such conditions, such as combines. With the application of this new technology, it is possible to increase the power of diesel engines by 15...20% and reduce fuel consumption by up to 14%. Further research will focus on substantiating the parameters of recycling systems for different classes of vehicles. Developing a methodology to justify the effective application of heat utilization systems in agricultural mobile energy vehicles is advisable. [ABSTRACT FROM AUTHOR]