R1150 exhibits high latent heat and evaporation pressure, whereas R1234ze(E) is environmentally friendly and boasts excellent thermal performance. Consequently, the binary mixture of R1150 and R1234ze(E) presents a potentially valuable working fluid pair. However, the limited data on its vapor-liquid equilibrium has hindered its practical engineering applications. To address this, this study investigates the vapor-liquid phase equilibrium of the R1150+R1234ze(E) binary mixture. A static analysis method was employed in the experimental system, achieving a temperature uncertainty of 4.2 mK and a pressure uncertainty of 0.001 MPa. The vapor-liquid equilibrium data for the R1150+R1234ze(E) binary mixture were measured within the temperature range of 223.15 K to 253.15 K and correlated using the PR-MHV1-NRTL and PR-WS-NRTL models. The results demonstrated good consistency when compared with experimental data.

R290/R245fa constitutes a non-azeotropic refrigerant pair suitable for auto-cascade ejector refrigeration cycles. However, the scarcity of experimental data and significant discrepancies among prediction models pose challenges. To enhance the accuracy of vapor-liquid equilibrium (VLE) data calculations for the R290/R245fa binary mixture, this paper utilizes the Peng-Robinson (PR) equation in conjunction with three mixing rules: the van der Waals (VDW), Wong-Sandler (WS), and Modified Huron-Vidal first-order (MHV1) mixing rules. Additionally, it employs the UNIFAC (Dortmund) activity coefficient model to evaluate the VLE properties of the mixture. The results indicate that the MHV1 mixing rule exhibits superior computational accuracy for low-pressure systems compared to the WS and VDW mixing rules. Considering the impact of hydrogen bonding forces among fluorinated hydrocarbon molecules on the vapor-liquid phase composition, the optimal model modifies the area and volume parameters of fluorine-containing groups within the activity coefficient model. This modification reduces the average relative deviation of pressure to 0.7937% and lowers the absolute deviation of the vapor-phase component to 0.0018. The prediction results demonstrate that the accuracy of the modified model is comparable to that of REFPROP 10.0, with a relative deviation of pressure between the modified model and REFPROP 10.0 amounting to 0.7051%, and an absolute deviation of the vapor-phase component of 0.0025.Finally, utilizing the modified parameters, the phase diagram for the R290/R245fa mixed refrigerant is plotted within the temperature range of 243.15 K to 283.15 K.

A two-stage separated auto-cascade refrigeration cycle, incorporating one or two fractionators, has been devised to enhance the refrigeration efficiency of the conventional two-stage separation-based auto-cascade refrigeration cycle (TSARC) and attain a lower refrigeration temperature. This cycle employs the zeotropic refrigerant mixture R1150/R600a as its working fluid. To assess the thermodynamic performance of various cycles—namely, the first-stage fractionation-based auto-cascade refrigeration cycle (FRARC), second-stage fractionation-based auto-cascade refrigeration cycle (SFARC), and two-stage fractionation-based auto-cascade refrigeration cycle (TFARC)—a thermodynamic model of a two-stage separation-based auto-cascade refrigeration cycle with two fractionators has been established. The results reveal an optimal composition ratio for maximizing the coefficient of performance (COP) in each of the proposed cycles. At a condensing temperature of 30℃ and an evaporating temperature of -90℃, the FRARC, SFARC, and TFARC achieve their peak COP, which are 4.9%, 6.6%, and 16.3% lower, respectively, than that of the TSARC. Additionally, these cycles yield the lowest refrigeration temperatures of -98, -98 and -100℃. The application of fractionation to the TSARC does not improve its thermodynamic performance but does facilitate the attainment of a lower evaporating temperature.

The separation efficiency of mixtures refrigerant is a main factor affecting the performance of auto-cascade refrigeration cycles. Fractionation purifies low-boiling compositions while reducing the mass flow rate in the evaporator, which may lead to a decrease in cycle performance. This article proposes a cycle that combines fractionation and flash separation. The cycle increases the refrigerant flow rate and purifies the compositions. The thermodynamic analysis results show that under the design conditions, the mass fraction of low-boiling compositions and refrigerant mass flow rate in the new cycle is increased by 5.37% and 17.80% compared to the basic cycle. The mass flow rate within the evaporator in the fractionation cycle decreased by 11.6%. The COP and efficiency of the new cycle are increased by 26.33% and 26.05% compared to the basic cycle. Therefore, the combination of fractionation and flash separation improves the performance of the auto-cascade cycle.

The technical bottleneck that solar intermittent energy supply limits the continuous heating capacity and energy efficiency ratio of solar direct expansion heat pumps urgently need to be solved. In this paper, a flashing booster-assisted ejector heat pump cycle (FB-EHPC) is proposed. The flash tank can separate steam and liquid after partial expansion, effectively reduce the discharge temperature of the compressor and improve the mass flow rate of refrigerant steam in the high pressure loop, which is conducive to improving the heating capacity at low evaporation temperature and realize the improvement of cycle performance. In this paper, a thermodynamic analysis model of FB-EHPC cycle was established, and R134a was used as the working medium to study the system performance changes under different working conditions, and a comparison was made with B-EHPC under different working conditions. Exergy efficiency and COP of FB-EHPC system increased significantly compared with B-EHPC system. Exergy efficiency increased by 6.03% while COP of FB-EHPC system increased by 16.64% in design condition.

Addressing the issue of low energy efficiency in high-temperature heat pumps under large temperature difference heating conditions, a novel auto-cascade high-temperature heat pump cycle is proposed. The cycle employs a cascade heating strategy to achieve high-temperature water heating. The zeotropic mixed refrigerant with low GWP is selected due to temperature glide characteristics. The HCs refrigerant is chosen for the low-boiling composition. A thermodynamic mathematical model is constructed to analyze the energy and exergy performance of the modified cycle. The result indicates that within the range of outlet water temperature variation, the heating COP and heating capacity increase by an average of 49.36% and 44.30%. The mass flow rate of the refrigerant is reduced by an average of 50.53%. The exergy efficiency is enhanced by 3.47 times. Therefore, the modified cycle demonstrates potential for improvement in both energy and exergy performance.

To ensure energy security, reduce pollution and combat global climate change, the automotive industry is rapidly shifting from conventionally fuelled vehicles (CFVs) to zero-emission pure electric vehicles (BEVs). A sophisticated, reliable and efficient vehicle thermal management system is essential to enhance BEV performance and alleviate range anxiety. As environmental regulations become increasingly stringent, the selection of low global warming potential (GWP) refrigerants for thermal management systems has become a pressing sustainability issue. The study establishes a numerical simulation platform for the thermal management system of a complete vehicle and selects low GWP alternative refrigerant schemes such as R744, R290, R152a and R1234yf. The basic performance differences between these refrigerant schemes are investigated, and the thermodynamic and environmental performance of each scheme is evaluated to establish a comprehensive evaluation system. The study shows that the R744 option has the highest heating capacity of 27.5 kW, R290 performs better in terms of cooling and heating efficiency, with an average energy consumption of 5% to 7% lower than that of the R134a option, and the R290 option exhibits excellent thermodynamic performance and environmental friendliness. A comprehensive evaluation shows that the R290 and R744 options are promising refrigerant choices for future BEV thermal management systems.

In order to study the feedback pressurization process in the ascent period of the rocket and the influence of the porous plate, this paper has established the 3D multi-phase, multi-component model to simulate the pressurized discharge of helium in the liquid oxygen tank. The tank pressurized discharge tests, conducted as Lewis research center, are applied to validate the numerical model. The temperature and consumption of helium are compared with the experimental results of 12% error. This verification can demonstrate the accuracy of the model proposed. And then, the porous plate is isometrically reduced, and a simplified model is constructed to calculate the pressure drop of liquid oxygen with multiple flow rates. The effect of the porous plate on the flow is limited to a very small region near the plate. The large pressure drop exists and calculated by the porous jump model coupling with the proposed model. The permeability ε and pressure jump coefficient c₂ in the porous jump model are acquired by fitting. The different flow resistance of the cryogenic propellant at different heights through the porous plate during the variation of overload results in bending of the interface. The temperature in the liquid phase remains almost constant, and the temperature in the vapor phase increases with the axis height increases along the direction of overload. The increasing overload leads to the high temperature jetting at the lower of the diffusion inlet. Thus, the thicker thermal stratified layer forms on the overload-directed side. The pressure in the cryogenic tank can be divided into three regions, with the pressure in the ullage remaining constant and the pressure in the liquid region rising as approaching the outlet. And the porous plate produces a sudden increase in the pressure. The phase change at the interface is dominated by evaporation until 72 s and condensation thereafter. Meanwhile, the existence of porous plate prevents the natural convection in the tank which increases the temperature at the interface. The increase in temperature results in that the evaporation dominates the phase change in the cryogenic tank. Correspondingly, the mass of phase change and outlet pressure increase 17.68% and 3% compared with the pressurized discharge process without porous plate, respectively. The present study is significant for the understanding of the pressurized discharge in cryogenic propellant tank and could provide recommendations for the design and optimization of pressurization systems and structure of porous plate for cryogenic propellants.

A finned elliptical casing evaporative condenser experimental test system was constructed, and the effects of head wind speed, inlet air wet bulb temperature, circulating cooling water temperature and flow rate on the heat and mass transfer performance of this condenser were investigated by using the control variable method.The experimental results show that as the frontal wind speed gradually increased from 2.5 m/s to 3.7 m/s, the air pressure drop outside the heat exchanger tubes increased by 6.07 times. The increase in frontal wind speed led to a rise in air pressure loss outside the tubes, but it significantly improved the heat and mass transfer performance. The external heat flux density and the external heat transfer coefficient increased by 22.3% and 25.6%, respectively, and the water film-air mass transfer coefficient outside the tubes increased by 19.1%, with the optimal frontal wind speed being 3.1 m/s. When the inlet air wet-bulb temperature increased from 9.6℃ to 11.6℃, both the external heat flux density and the external heat transfer coefficient of the heat exchanger decreased by 92.2%. As the circulating cooling water temperature rose from 17℃ to 33℃, the internal heat flux density decreased by 47.8%, and the internal heat transfer coefficient decreased by 38.1%, indicating that higher inlet air wet-bulb temperature and circulating cooling water temperature both reduce the heat transfer performance of the heat exchanger. Increasing the cooling water flow rate from 0.066 m³/h to 0.162 m³/h resulted in increases of 83.4% in internal heat flux density and 91.4% in internal heat transfer coefficient, demonstrating that increasing the cooling water flow rate can significantly enhance heat transfer performance. This study provides a reference for further exploration of the heat and mass transfer processes in evaporative condensers and their application in practical engineering.

The fin and tube heat exchanger is the most commonly used type of heat exchangers in household air conditioners. The most direct way to reduce the production cost of fin and tube heat exchangers is the replacement of copper tubes with aluminum tubes. There is a lack of design experience in the aluminum tube and aluminum fin heat exchanger currently, and the development of a simulation model to predict performance can improve design efficiency. This study builds a three dimensional steady state distributed-parameters model of heat exchangers, and the adjacent matrix in graph theory is introduced to describe the complex refrigerant circuitry in heat exchangers. An overall alternating iterative algorithm is adopted, and energy equations for all control volumes and momentum equations of all control volumes are solved dependently to decouple the relationship of conservation equations. A digital simulation design software with an interactive graphical interface is implemented. Experimental validations on prototypes with different combinations of aluminum tubes and aluminum fins are carried out, and the comparison between the experimental results and the simulation results shows that under four working conditions, the deviations of predicted heat transfer, pressure drop inside and outside the pipe are within ±5%, ±10%, and ±10%, respectively. The aluminum tube and aluminum fin heat exchanger model can meet the accuracy requirement of design.

The Labyrinth valve core is a key component for controlling high-pressure liquid flow. The cavitation phenomenon in its flow channel structure is one of the bottlenecks that restricts flow adjustment. The numerical simulations have been conducted through SST k-ω turbulence model and Rayleigh-Plesset cavitation model to investigate the flow and cavitation characteristics in zigzag and array labyrinth flow channel structures. A modified trim structure was proposed that meets the requirements of low cavitation intensity and high mass flux. The results indicate that the mass flow rate of the zigzag channel was lower under identical pressure difference between inlet and outlet. The cavitation intensity was increased in zigzag channel due to the occurrence of strong boundary layer separation and the appearance of large-scale vortex regions. As for array channel, the cavitation phenomenon was observed in wake region of the final cylinder. By modifying the final cylinder to a water-droplet streamline structure, the local cavitation could be significantly mitigated while maintaining elevated mass flux. When the tail angle b=30°, the average cavitation reaches the lowest value of 41.9%. This suggests the existence of an optimal angle that minimizes the cavitation rate at the downstream outlet section. The present study can offer a theoretical foundation for optimizing the trim structure, enhancing the anti-cavitation performance, and improving the fluid mass flux of labyrinth regulating valves.

For the stability of plate heat exchanger in the dynamic ice storage system, Fluent is employed to investigate the variation rules of the heat transfer coefficient, temperature distribution and pressure drop parameters under the plate structure with different pitches, heights and angles of corrugated plate. The results indicate that: At smaller corrugation pitch (6 mm), the number of contact points increases, which leads to a enhancement of heat transfer and a more uniform temperature distribution; The increase of the corrugation height can increase the heat transfer area of the corrugated plate, but also leads to the flow velocity slowing down and the generation of high temperature stagnation zone, which is not conducive to improving the heat transfer efficiency of the corrugated plate; The change of corrugation angle effects the flow shape in plate heat exchanger. With the increase in the angle of the corrugation from 60° to 150°, the heat transfer efficiency is firstly elevated and then lowered. There is the best heat transfer effect at 120°. The complex flow with a large proportion of zigzag flow accompanied by cross flow has a more efficient heat transfer.

In cosmic exploration, a dependable low-temperature environment is indispensable for space detectors. The valved linear compressor (VLC) functions as the core component in the Joule-Thomson (JT) throttling cryocooler, with its structure and performance having a direct bearing on the cryocooler's cooling efficacy and efficiency. To attain lightweight and efficient VLCs for space applications, the motion characteristics of the double-acting piston structure are analyzed, building on the research foundation of our group. The gas load is then determined using the describing function method. By optimizing the motor structure and gas valve, an independent two-stage VLC prototype is developed, accompanied by variable parameter studies across different charging pressures and piston strokes. Experimental findings reveal that as the charging pressure rises from 0.1 MPa to 0.3 MPa, the mass flow rate increases by 337%, while the pressure ratio decreases by just 19.7%. Both motor efficiency and isentropic efficiency peak at 0.15 MPa. As the piston stroke expands from 2 mm to 10 mm, the mass flow rate multiplies by 10.6, and the pressure ratio increases by 9.6 times. Motor efficiency peaks at 4 mm, whereas isentropic efficiency demonstrates a linear increase with stroke length. Testing confirms that this compressor's maximum output performance is 16 mg/s at a pressure ratio of 19.7, sufficient to match the output capacity of two single-stage compressors. The creation of this prototype establishes a foundation for meeting the lightweight and efficient demands of future space throttling cryocoolers.

Forest fires have immense destructive power, and aerial firefighting is the safest and most efficient technique for combating them. Under the coupling effects of high-altitude wind fields and ground fire conditions, the fire extinguishing medium sprayed at high speed rapidly expands, fragments, atomizes, and evaporates, causing a loss of firefighting effectiveness. To understand the evaporation characteristics of the extinguishing medium, a model of droplet evaporation under thermal convection conditions is established in this study, including the dynamic equations of the heat transfer and mass transfer, and a visualized experimental setup for measuring droplet evaporation characteristics is carried out. The evaporation processes of water and gel fire extinguishing agents are observed, and the rates of change in droplet diameters are measured. The model is validated based on the experimental data. The experimental validation shows that the proposed model accurately reflects the evaporation characteristics of water and fire extinguishing agents, and the model's prediction results agree well with the experimental data, with the deviations of droplet radius being less than ±0.2 mm.

An anti-frosting strategy using ultrasonic wave and hydrophobic surface to drive droplets is proposed. The transport behavior of droplets on the aluminum plate surface under ultrasonic excitation is studied experimentally. The effects of ultrasonic power, droplet volume and surface hydrophobicity on the diameter spreading rate, average velocity of droplet are analyzed. The results show that the droplet undergoes four stages of spreading deformation―motion―atomization―evaporation under the action of ultrasonic wave. The droplet diameter spreading rate increases with the increase of ultrasonic power, but the droplet volume has no significant effect on it. The average velocity is positively correlated with ultrasonic power and droplet volume. Compared with the bare aluminum surface, the diameter spreading rate of droplet on the hydrophobic surface increased to about 1.15 times, and the average velocity increased to about 6 times.

Suppression of condensation frosting is essential for a variety of frost protection applications. However, icing of supercooled droplets at surface edges or defects can eventually lead to icing of the entire surface. For this reason, six hydrophilic and hydrophobic surface-bound hygroscopic solutions were designed and fabricated for experiments in this paper. Frosting tests show that changing the spatial distribution of the hygroscopic droplets has a significant effect on retarding the frost propagation rate. Among them, discontinuous ringlike stripe biphilic with breakpoint 16 (DRSB-16) showed an overall frost coverage time of 228—251 min under the set working conditions, which improved the frost suppression performance by 64%—74% compared with other hygroscopic solution frost suppression studies. The application of hygroscopic solutions and hydrophilic surfaces is expanded and valuable insights are provided for the application of amphiphilic surfaces and for the design of surfaces with customized frost protection properties.

In order to improve the energy efficiency of the system operation, air-conditioning systems use a distributor to achieve a uniform distribution of the two-phase refrigerant in the multi-channel fin-and-tube heat exchanger. The venturi-type distributor used in air-conditioning systems has a complex flow channel structure and requires multiple capillary tubes as fittings, which makes its cost high. In this paper, a new type of casing-type distributor is proposed to achieve uniform distribution of quality in each flow path by dispersed bubble flow, and to achieve uniform distribution of flow rate in each flow path by equal-pressure mixing and circulating. The design formula and model for the key structural parameters of the casing-type distributor are proposed and the distribution effect of the casing-type distributor is verified by experiments. Compared with the traditional venturi-type distributor, the unevenness of the casing-type distributor is reduced by 18%, and the production cost of the casing-type distributor is reduced by 30%.

Immersion and jet technology is the future development direction of data center server liquid cooling. A single-server liquid cooling test bench was built to compare the heat dissipation performance of pure immersion and immersion jet liquid cooling systems. On this basis, the effects of inlet water temperature, jet distance and inlet water flow rate on the performance of immersion jet system were analyzed. The experimental results show that in the pure immersion liquid cooling system, the inlet water temperature is reduced from 27.0℃ to 18.0℃, which can reduce the stable temperature of the server surface from 47.4℃ to 41℃, but it also increases the temperature difference between the inlet and outlet water. In the submerged jet liquid cooling system, when the jet distance is reduced from 10 cm to 1 cm, the steady-state surface heat transfer coefficient can be increased by about 467.3 W/(m²·K), and the heat exchange uniformity of the system is better at 3 cm. The steady-state surface heat transfer coefficient can be increased to 3136.2 W/(m²·K) when the inlet water flow rate is increased from 8 L/min to 18 L/min, which is about 2.1 times of that at low flow rate. Subsequently, the potential of submerged jet liquid cooling technology in large-scale applications can be further explored.

The injection or return of cold water into a steam line results in the formation of a two-phase flow with a large temperature differential within the piping. This phenomenon gives rise to the condensation of steam and the generation of water hammer, which in turn causes transient peak pressure pulses. Such pulses have the potential to cause damage to the piping. In order to forecast the pressure load of condensation hammer, this paper establishes a six-equation mathematical model of compressible two-fluid flow taking into account the elastic deformation of pipeline cross-section, which is closed by the real physical equation of state, the two-phase flow pattern discrimination formula and the flow heat transfer calculation model library. The model is used to simulate high-temperature steam condensation hammer and to forecast the pressure load by a self-programmed procedure. The PMK-2 test based on condensation water hammer verified the calculation accuracy of the model, and the prediction result of the pressure peak deviated from the test value by 1.7%. Numerical simulations were carried out for two working conditions: cold water injection into steam pipes and non-energetic waste heat discharge. The effect of cold-water flow rate, temperature and pipe diameter on condensation water hammer was investigated using the model in this paper. The findings revealed that an increase in cold water flow rate results in a corresponding rise in peak pressure pulse, while an increase in liquid phase temperature leads to a reduction in peak pressure. Additionally, the study demonstrated that when pipe diameter is sufficiently small, the water hammer phenomenon is no longer observable.

Sessile droplets on a flat plate can absorb ultrasonic vibration and move directionally. Utilizing the piezoelectricity-acoustic streaming effect to propel droplets away from the surface directionally shows promise in inhibiting frost formation during the early stage of condensation droplets. In this study, a droplet propel technology based on the piezoelectricity-acoustic streaming effect is proposed. An experimental device with a glass flat surface as the substrate was developed, the working principle of the device was analyzed, and the effects of driving voltage and droplet volume on droplet movement speed are studied. This method can drive droplets larger than 50 μl with a voltage above 35 V, and under experimental conditions, the maximum droplet movement speed reached 88 mm/s. The results indicate that directional driving of droplets using the piezoelectric acoustic streaming effect is an effective method for defrosting formation.

Precooling the LNG carrier prior to loading is a critical process to ensure the reliability of cargo equipment and enclosure structures. This study investigates membrane LNG carriers by constructing a two-dimensional cylindrical mesh using similar methodologies, simulating both the flow distribution within the tank and the enclosure temperature. The calculations not only demonstrate efficient performance but also accurately capture the variations in the temperature gradient. The results highlight the importance of monitoring temperature changes at the center and corners of the bottom. To ensure that the main enclosures cool at a safe gradient, an operational strategy regarding the rate of liquid supply should be carefully considered.

An analysis model is established to study the heat leakage process in a liquid cargo tank, enabling the calculation of the temperature field distribution of the membrane-type cargo under various working conditions. Based on the calculated temperature field distribution data, the heat leakage and pressure holding time are analyzed. The influence of ambient temperature, filling rate, and cabin pressure on the temperature field distribution and the variation of holding time are discussed. The results indicate that when the ambient air temperature rises from 20℃ to 45℃, the heat leakage of the cargo tank increases by 4.17 kW, while the holding time decreases by 11.1 h. The ambient air temperature primarily affects the temperature distribution in the cabin above the water level. As the filling rate increases from 50% to 98%, the reduction in gas phase space enhances the solid-liquid heat transfer area of the bulkhead, leading to an overall heat leakage increase of 85.2 W in the liquid cargo tank, and the holding time extends by 121.2 h. There exists an optimal loading rate for achieving the longest holding time, with the maximum holding time of 317.8 h occurring at a loading rate of 95%. When the cabin pressure increases by 20 kPa above atmospheric pressure, the temperature gradient between the interior and exterior of the cargo decreases, resulting in a heat leakage reduction of approximately 1.09 kW.

The non-uniform distribution of wind velocity generated by the axial fan on the outside of the window air conditioner will lead to non-uniform distribution of refrigerant in the condenser and thus deteriorate the heat transfer performance, so it is necessary to analyze the characteristics of the wind velocity distribution and adjust the design of the flow path to match with it, so as to realize the performance improvement of the condenser. This paper takes the window air conditioner condenser as the research object, establishes the numerical model of non-uniform wind velocity contour of axia fan, and carries out three-dimensional numerical simulation of non-uniform wind velocity distribution. The wind velocity simulation results are discretized into a grid distribution of 18×10 and substituted as boundary conditions into CoilDesigner software to analyze the effect of the axial blowing wind velocity distribution on the performance of the condenser, and the accuracy of the model is verified by experiments, and the deviation of the model's heat exchanger calculation results is less than 2%. The simulation results show that the non-uniformity of the wind velocity distribution increases with the increase of the fan speed, and when the speed is increased from 1200 r/min to 2000 r/min, the extreme deviation and variance of the wind velocity increase by 1.95 m/s and 0.460 m²/s², respectively; furthermore, the effect of the non-uniform wind velocity distribution on the heat exchange performance of the condenser is analyzed, and it is found that the heat exchange coefficient of the condenser in the central static zone of the axial wind contour is smaller while in the bottom accelerated zone, the heat exchange coefficient is smaller than in the bottom accelerated zone. It is found that the heat transfer coefficient of the condenser in the center static zone of the axial wind field is small and the heat transfer coefficient in the bottom accelerated zone is large, and in the process of flow path design, it is necessary to increase the heat transfer area of the branch arranged in the center static zone, so as to make the heat load of the different branches equal, and to match the bottom accelerated zone with the pipeline of the refrigerant flow rate that is large to have a larger heat transfer coefficient, so as to enhance the performance of condenser. Finally, 20 flow path arrangement schemes are designed and simulated to investigate the influence of piping configuration on condenser performance under the non-uniform wind velocity distribution of axial fan, and the simulation results show that, compared with the original flow path, extending the length of the center static zone pipe, placing the convergence section in the bottom acceleration zone, and placing the convergence point of the branch in the leeward side, the heat exchange capacity can be increased by 1.8%, and the pressure drop can be reduced by 26.1%.

In comparison to single-use launch vehicles, reusable launch vehicles (RLV) are gaining significant attention due to their high efficiency, low cost, and broad application scope. However, their unique flight profiles also subject them to more complex variations in g-loading, such as axial negative gravity experienced by lower stage during specific flight phases, presenting new technical challenges in propellant management. Existing studies highlight the unique advantages of perforated plates in managing propellant under negative gravity. Consequently, this paper explores the liquid retention capabilities of perforated plates from multiple perspectives. The present study focuses on the liquid oxygen (LO _X ) tank of a typical launch vehicle. A three-dimensional CFD simulation model, based on the volume of fluid (VOF) method, was constructed to capture the gas-liquid interface. Using this model, the LO _X flow behavior was simulated under different perforated plate arrangements, different initial liquid conditions and varying negative gravity. The retention effect of perforated plate was analyzed from two perspectives: the upward ejection of LO _X and the downward movement of O₂ bubbles. The results of this study indicate that perforated plate can effectively prevent LO _X upward ejection, reducing the outflow by 95.63% under a -0.20g negative gravity; additionally, the outflow rate of liquid oxygen is positively correlated with the degree of negative gravity. The influence on liquid oxygen outflow is negligible when the liquid level is above or below the perforated plate and remains horizontal; however, when the liquid level is inclined, a rapid and significant outflow of liquid oxygen occurs due to the gas-liquid circulation channels above and below the perforated plate. The submergence speed of gas is influenced by both the morphology of bubbles and the degree of negative gravity. When the propellant fills up to the height of the perforated plate and the vehicle, tilted at 10°, is subjected to a -0.20g negative gravity, the bubbles grow rapidly, reaching an effective submergence speed of 0.317 m/s. This speed exceeds that observed under a -0.40g negative gravity with a horizontal liquid level. Therefore, the arrangement of the perforated plate should comprehensively consider factors such as volume of remaining propellant, rocket gimbal angle, and degree of negative overload.

The flow pattern of CO₂ boiling in a horizontal smooth tube with an inner diameter of 5 mm is visualized under diabatic conditions. The flow pattern maps of CO₂ are obtained for the experimental evaporation temperatures of 7—15℃, heat flux of 5—35 kW·m^-2, and mass flux of 100—500 kg·m^-2·s^-1. The two-phase flow patterns in the tube include bubbly flow, plug flow, slug flow, stratified-wave flow, annular flow and mist flow. The experimental results show that the liquid film at the top of the annular flow dries out prematurely at low to medium quality and the heat transfer coefficient gradually decreases. The reduction of evaporation temperature and the increase of mass flow rate help to stabilize the liquid film around the tube, which can effectively inhibit the decrease of heat transfer coefficient due to early dry-out. When the mass flux is 400 kg·m^-2·s^-1 and the heat flux is 30 kW·m^-2, the heat transfer coefficient at the top of the tube at the evaporation temperature of 7℃ is about 40% higher than that at 15℃.

The accurate analysis of the distribution of airflow tissue in plant factories is an important basis for the study of plant healthy growth, but there is a lack of research on the distribution of \mathrm{C}{\mathrm{O}}_{\mathrm{2}} concentration in plant factories. Computational fluid dynamics (CFD) method was used to establish a mathematical model of porous media and net photosynthesis, and the concentration of \mathrm{C}{\mathrm{O}}_{\mathrm{2}} and energy consumption of air supply fans under different air supply speeds were explored. Based on the NSGA-Ⅱ genetic algorithm, multi-objective optimization was carried out with the velocity of the air supply outlet as the decision variable, the airflow velocity of the plant area, the concentration of \mathrm{C}{\mathrm{O}}_{\mathrm{2}}and the energy consumption of the fan as the objective functions, and the Pareto optimal solution was obtained. When the air supply speed was 3.26 m/s, the average velocity of the plant area is 0.37 m/s and \mathrm{C}{\mathrm{O}}_{\mathrm{2}} concentration of the plant area is 277 \mathrm{\mu }\mathrm{m}\mathrm{o}\mathrm{l}/\mathrm{m}\mathrm{o}\mathrm{l}, and the energy consumption of the fan is 23.26 W.

A numerical simulation model for slurry transport within the chamber of an ultra-large-diameter slurry shield tunneling machine is established based on computational fluid dynamics (CFD) methods. A theoretical approach for calculating the critical non-silting velocity in the air cushion chamber is proposed, and the internal flow field characteristics under different jet nozzle angles, both in front of the grille and behind the slurry gate, are analyzed. When the jet angle behind the slurry gate is set to α = 45°, the flow field is optimized, leading to an increase in the average velocity across the grille section, enhancing the slurry jet's transport capacity for soil agglomerates, and promoting particle entry into the grille. The critical non-silting velocity is found to range from 1.68 m/s to 1.80 m/s, with higher proportions of large particles requiring greater velocities. At α = 45° and α = 60°, the flow velocity in the lower central chamber exceeds the critical value, effectively reducing the risk of debris deposition. Moreover, the overlap of jet turbulence diffusion zones at the grille enhances particle transport efficiency. When the jet angle in front of the grille is set to β = 30°, turbulence-induced disturbances effectively prevent the deposition of easily flocculated fine particles. These findings provide valuable insights for improving the transport efficiency of soil and rock particles within the chamber and mitigating sediment blockage in the air cushion chamber.

MIL-53 is an important material for the adsorption and separation of xylene isomers, in which MIL-53(Cr) has high selectivity for o-xylene (OX) and p-xylene (PX), but low selectivity for OX and m-xylene (MX). To improve the selectivity of MIL-53(Cr) to OX and MX, a strong alkaline site was directly introduced into MIL-53(Cr) through a redox action between the base precursor KNO₃ and the metal center Cr³⁺. This alkali-modified MIL-53(Cr) was then tested as an adsorbent for the liquid-phase separation of OX, PX, and MX. The results show that the introduction of basic sites in MIL-53(Cr) does not alter the unique structure of the material. However, because the newly introduced alkaline sites partially occupy the metal sites, the adsorption capacity for xylene decreases. The adsorption selectivity for OX/PX remains unchanged, while the material's resistance to adsorption of MX increases with the density of basic sites, resulting in a decrease in overall adsorption capacity. Notably, the OX/MX adsorption selectivity improved from 2.3 for MIL-53(Cr) to 4.1 for the modified K-MIL-53(Cr). K-MIL-53(Cr) demonstrates excellent stability and regeneration ability. After five adsorption cycles, its adsorption capacity only decreased by 5.7%, and the structural integrity of the material remained largely unchanged.

This paper proposes a Matlab/Simulink-based simulation method for temperature control in large-scale high and low temperature environmental laboratories. The laboratory model is simplified and established using the lumped parameter method, integrating factors such as thermal capacity, thermal resistance, heat sources, and heat losses. By adjusting the compressor operation ratio of the cooling system, the power of electric heaters, and the status of icing and de-icing systems, precise temperature control is achieved. The research findings indicate that, under various temperature settings, the temperature regulation time remains the shortest when the icing system is engaged at the PID inflection point, reinforcing the application value of this strategy. Furthermore, after introducing the fuzzy PID control strategy, fuzzy PID control exhibits superior performance in terms of response speed and overshoot suppression.

Linear compressors offer superior performance with excellent capacity modulation, enhancing system efficiency and enabling adaptation to a wide range of operating conditions. These characteristics make them highly suitable for applications in refrigeration and cryogenic systems. Gas bearing technology facilitates oil-free lubrication and ensures high reliability in linear compressors. Carbon dioxide (CO₂), as an environmentally friendly refrigerant, has a low global warming potential (GWP) and an ozone depletion potential (ODP) of zero, along with excellent thermophysical properties. In this study, a porous gas bearing model is developed using CO₂ as the working fluid. Simulations are performed using Fluent software to evaluate the influence of porous material thickness, gas gap thickness, supply pressure, and eccentricity on the gas consumption and load capacity of the gas bearing. Using response surface methodology, the optimal design parameters were determined to be a gas gap thickness of 10.0—11.1 μm and a porous material thickness of 2.11—3.50 mm. These results provide a valuable reference for the design of gas bearings in CO₂ linear compressors.

Extensive application of energy storage batteries in the field of energy storage demands efficient thermal management systems to ensure their safety and performance. Due to its excellent temperature uniformity and high efficiency, direct cooling technology has attracted attention in the field of battery thermal management. This experimental system utilizes the two-phase vaporization process of refrigerant in the cold plate channels to achieve efficient temperature control and uniformity for the battery pack. The experimental results show that under an ambient temperature of 25℃, with a 500 W heat load and a compressor frequency of 40 Hz, the surface temperature of the cold plates remains uniform, with a maximum temperature difference controlled within 0.4℃. Additionally, the temperature variation between the cold plates is minimal, with an average temperature difference of only 0.28℃, indicating good system temperature uniformity. Pressure drop analysis reveals that the pressure loss between the cold plate inlets and outlets ranges from 4.99 kPa to 21.52 kPa. By optimizing compressor frequency and other operating parameters, system performance can be further enhanced. The study provides valuable insights for the optimized design of thermal management systems for energy storage batteries.

Chemical absorption using alcohol amine solution as an absorbent is currently the most widely used technology in the field of natural gas decarbonization, with advantages such as large processing capacity and good cycle stability. However, the regeneration process of chemical absorbent consumes a lot of energy. To reduce the energy consumption of chemical absorption decarbonization, a natural gas chemical absorption decarbonization high-temperature heat pump coupling process is proposed. Through the high-temperature heat pump, the waste heat from the wastewater in the gas field is used for the regeneration process of the decarbonization process, achieving energy conservation and carbon reduction. Modeling and parameter optimization of the decarbonization system using MDEA solution was carried out using Aspen HYSYS software. The results showed that the decarbonization rate of the optimized process was as high as 95%, and the unit comprehensive power consumption of the system was 0.3821 kW·h/kg CO₂, which was 56.72% lower than the conventional decarbonization system (unit comprehensive power consumption of 0.8828kW·h/kg CO₂).

With the gradual depletion of conventional oil and gas resources globally, mankind has started to focus on the exploitation of unconventional oil and gas resources. As a significant unconventional resource, deep oil and gas hold immense exploitation potential. However, at present, ultra-deep well drilling technology remains imperfect, and the process encounters technical challenges, such as drilling equipment's inability to endure the high temperatures of these wells. Adsorption-type cold storage equipment, characterized by its small size, high cold storage density, wide working temperature range, and vibration resistance, stands as an ideal solution for cooling and temperature maintenance in high and ultra-high temperature drilling operations. To complement the drilling equipment, a modular cylindrical adsorption cold storage system was designed. This system employs a NaY-type zeolite molecular sieve-water pair and features an adsorption bed length of 0.87 m. In a downhole environment of 200℃, the system can maintain the temperature of electronic components in the drilling equipment at 125℃ for 30 h, meeting the demands of a single downhole operation. This innovation offers a fresh perspective for the design of high-temperature-resistant drilling equipment.

The solar-powered absorption refrigeration cycle is plagued by inherent deficiencies, such as poor performance and potential operational failures, especially under varying conditions. Although solar-powered absorption refrigeration stands as a nearly electricity-free refrigeration technology, its operational performance is significantly hindered by the intermittent nature of solar energy and fluctuating user demands. From the perspective of internally matching parameters with external conditions, a state-space model for a solar-powered single-effect LiBr-H₂O absorption refrigeration cycle is established based on modern control theory. This dynamic model of the solar-powered absorption refrigeration cycle has been validated through steady-state simulations and experimental results, and its dynamic response characteristics have been evaluated under various disturbances. The findings suggest that the state-space dynamic model not only captures the dynamic characteristics of the solar-powered absorption refrigeration cycle but also elucidates the dynamic relationships among input variables, state variables, and output variables.

Waste heat recovery is an essential solution to optimize the energy consumption structure of data center as well as save energy and reduce carbon emissions. This paper constructed a model of compression-absorption refrigeration system driven by waste heat in liquid-cooled data center, and investigated the influence of supply-side heat source temperatures, cooling water temperature and other parameters on the refrigeration performance. The coordination method of compression ratio and cooling water temperature was researched to compensate for system performance under variable cooling conditions. Combined with the year-round climate analysis in Beijing, the analysis of the refrigeration characteristics driven by waste heat source of a typical server with different heat dissipation powers was carried out, and it was concluded the performance was improved by the increasing temperature of the supply-side heat sources. The operating range of cooling water temperature was widened by 6.5℃ to 8.7℃ as the compression ratio increased from 1.2 to 1.8. In transition seasons and winter, plentiful natural cooling sources can maintain the operation of single-effect absorption refrigeration system with considerable performance, and provide effective natural cooling for servers. During the period of the environmental temperature on average, only a handful of compression power was spent in achieving efficient refrigeration. When operating in the extremely hot climate, the compression power equivalent to 15% to 20% of the waste heat was consumed to maintain efficient refrigeration. The system achieves waste heat recovery with high efficiency in most of the time of the year from the theoretical analysis. In future research, the development of new types of working pairs, the optimization of energy consumption under extreme climatic conditions, and the design and maintenance of system devices are technical difficulties that need to be broken through.

In the context of decarbonizing industrial heat demand, ultra-high temperature heat pumps, serving as active thermal energy recovery systems, are emerging as pivotal technologies for energy conservation and emission reduction. These systems convert low-grade waste heat into high-grade thermal energy with minimal electrical energy consumption. While augmenting the number of heat exchangers and compressors and refining their layout have proven beneficial in boosting system performance, they inevitably introduce complexity, posing additional hurdles for system analysis and optimization. To address this, feature importance-based variable selection techniques offer an effective means of reducing data dimensionality and swiftly pinpointing crucial system components. However, traditional correlation analysis methods frequently falter in producing consistent results when data is missing. To overcome this limitation, this study introduces a novel method for quantifying feature importance using the random forest model. Analytical results reveal that the random forest approach demonstrates superior generalization abilities when applied to 100 datasets containing missing data, achieving a variance in feature importance quantification of 0.11505, notably lower than the 0.17055 variance attained with the correlation coefficient method. Moreover, the results indicate that coupling temperature is the primary determinant affecting system performance, thus identifying a key area for further optimizing system design. Additionally, the study finds that the influence of output temperature on system efficiency is less than 5%, suggesting the system's low sensitivity to variations in output temperature and emphasizing its potential for ultra-high temperature applications.

With the formal enforcement of the Kigali Amendment, the use of R134a in future vehicle air conditioning systems will be restricted due to its high global warming potential (GWP). To study the feasibility of low GWP refrigerants as replacements, this study first conducts a thermodynamic performance analysis and multi-factor evaluation of R1234yf, R1234ze(E) and R290 across four actual automotive operating conditions, with comparisons to R134a. Additionally, a range model is developed to assess the range performance of these refrigerants under varying winter ambient temperatures. The results indicate that R1234yf has a similar volume cooling/heating capacity and compatible compressor displacement when compared to R134a. The coefficient of performance (COP) and cooling/heating effectiveness of R1234ze(E) are also found to be comparable to those of R134a. In extreme cold winter conditions, R290 demonstrates a notable performance advantage, with COP_h and q_cv that are 2.3% and 57.3% higher than R134a, respectively. Furthermore, under heat pump operating conditions, R290 shows a slower rate of range decay compared to R134a. This study provides valuable insights into the substitution and application potential of efficient and environmentally friendly refrigerants in the field of vehicle air conditioning.

The air conditioning system in civil aircraft provides a comfortable thermal environment for the cabin, serving as a critical system to ensure the health and safety of passengers. Currently, most civil aircraft utilize a three-stage pressure-boosting high-pressure water removal system, which employs engine bleed air as the heat source and ram air as the cooling source, leading to significant fuel penalty losses. To analyze the economics of civil aircraft air conditioning systems, this paper establishes a dynamic simulation model of aircraft air conditioning system and presents a method for analyzing fuel penalty losses. The operating parameters of the system are calculated based on dynamic models and algorithms for key components such as air cycle machines and heat exchangers, combined with engine performance maps to obtain specific fuel consumption, thereby achieving the performance simulation of the air conditioning system and the analysis of fuel penalty losses. The results show that the bleed air used by the air conditioning system has a substantial impact on the system's fuel penalty losses. At a cruising altitude of 31000 ft, the fuel penalty loss caused by the bleed air accounts for 51.3% of the total fuel penalty loss of the system. An overall optimization of 10% in the air conditioning system's bleed air can reduce the total fuel penalty loss by 5.3%.

As a special equipment capable of simulating plateau conditions, the plateau environmental chamber plays a vital role in the field of special equipment testing. It can be used to provide extreme operating environments such as low pressure and low temperature of the plateau under normal ground conditions, thereby enabling the conduct of plateau testing experiments under normal ground conditions. Based on a plateau environmental simulation platform for automotive logistics equipment power equipment in Tianjin, this paper analyzes and reasonably simplifies each part of the platform to establish a mathematical model and conduct simulation research in Matlab/Simulink. The results show that the equipment selection of this plateau environmental simulation platform meets the set environmental test requirements, realizing the green and efficient design of the environmental test chamber. In addition, by studying the PID controller, the control logic of the environmental test chamber is explored, revealing the mutual influence between temperature, humidity, as well as the pressure.

The energy efficiency evaluation index of multi-split air conditioner (VRF) system has been converted into the annual performance factor (APF). To improve the APF performance of VRF system, it is necessary to improve the design efficiency through computer simulation. Based on the component models and solving method of VRF system, this article proposes a correction method for low-temperature heating under unsteady conditions, using factors such as compressor frequency and indoor and outdoor fan wind speed to correct system performance parameters, and obtain the average value of system performance during the defrosting cycle. Based on modular framework design, a multi-split air conditioner APF performance simulation software has been developed. The accuracy of the software has been verified through experimental data, and the prediction errors of the software for the system capacity and power of a single APF condition are within 7%, and the prediction errors for the overall APF of the system are within 5%. The results show that the multi-split air conditioning system APF performance simulation software developed in this article has good accuracy and can meet the needs of system optimization.

As a new type of HCFOs heat pump working medium, R1233zd(E) has a higher critical temperature (166.5℃) and a lower critical pressure (3.62 MPa), which is very suitable for high temperature and high temperature heat pump application. Therefore, this paper designed the R1233zd(E) high temperature heat pump system and built a heat pump prototype for experimental research. The experimental results show that the R1233zd(E) high temperature heat pump prototype can stably realize the high temperature heating of 120—145℃ within the evaporation temperature range of 40—65℃. When the condensation temperature is unchanged, the power consumption, heating capacity and COP of the R1233zd(E) high temperature heat pump prototype increase with the increase of evaporation temperature. Under the conditions of evaporation temperature of 65℃ and condensation temperature of 145℃, the power consumption of the R1233zd(E) high temperature heat pump prototype is 43.2 kW, the heating capacity is 96.8 kW, and the COP is 2.24. At the same time, the high temperature heat pump of the residual heat source is applied in the heat treatment production line to supply 120℃ high temperature hot water, replacing the original high temperature steam for heating. The heating capacity of the unit is 104 kW, the power consumption is 31 kW, and the COP can reach 3.4, which indicates that the energy efficiency of the system is very excellent. Compared with the original gas boiler, the operating cost can be saved about 127500 CNY/a, and the investment payback period is not more than 2 years.

Hexamethylene diisocyanate (HDI) is a pivotal chemical primarily synthesized through the photogasification reaction of hexamethylenediamine and phosgene. In isocyanate products, the content of hydrolyzed chlorine serves as a vital indicator for quality control, significantly impacting the product's stability and performance. This study delves into the formation mechanism of hydrolyzable chlorine by-products during the preparation of HDI. We analyzed the influence of oxygen content, heating time, and superheating temperature on the types and quantities of hydrolyzable chlorine, and subsequently proposed corresponding control strategies. Experimental results reveal that oxygen in the amine solution notably affects ethylenediamine. Specifically, during the heating process, oxygen accelerates the formation of hydrolyzed chlorine. Pretreatment of the amine solution to remove oxygen can effectively mitigate the formation of hydrolyzed chlorine. Additionally, the superheating temperature of hexamethylenediamine should be carefully balanced between acceptable levels of hydrolyzed chlorine and the risk of equipment blockage, thereby minimizing the production of hydrolyzed chlorine without causing equipment issues.

A solar heat pump drying system of water source is designed for the region of high cold. A cascaded latent heat thermal storage (CTS) device with three stages is integrated in the system for thermal management on the energy of heat pump. The numerical model of the system is constructed by the dynamic simulation platform of TRNSYS. The thermal characteristics of the CTS device are obtained by COMSOL numerical simulation, where the thermo-physical parameters of the phase change materials (PCMs) encapsulated are derived from three stereotyped composites of PCMs based on sodium acetate trihydrate. The operational characteristics of the system are studied before or after the integration of the CTS device. The results show that after the integration with the CTS device, the average temperature in the dry area increases by 7.76℃, the average relative humidity decreases by 8.5%, and the maximum day-night temperature difference and the maximum day-night relative humidity in the room decrease by 5.35℃ and 14.67%, respectively. The average COP of the heat pump reaches 3.40, which is 8.9% larger than that of the heat pump without the integration of the CTS device. The CTS device stores and transfers the daytime solar radiation to the nighttime circulation mode, which is beneficial for the utilization of uneven solar thermal radiation. Consequently, its integration into the heat pump system has a great potential to improve the operational efficiency and stability of the heat pump.

As a unique industrial sector in China, the brewing industry has substantial heat demands in production, with the alcohol, beverage, and refined tea sectors consuming 1.96×10⁸ GJ of heat annually. Given this profile, brewing is well-suited to pioneer industrial heat electrification, setting a model for other sectors. Industrial heat pumps, known for high efficiency and environmental benefits, are essential for this transition. This study introduces a brewery heat system centered on industrial heat pumps, validated in practical applications, showing stable heat supply and notable cost savings—only 57.5% and 54.3% of the costs of gas and electric boilers, respectively. With improvements in pump efficiency and renewable energy share, electrified heating via industrial heat pumps is poised for even greater carbon-reduction impact.

This paper presents a novel experimental and analytical waste heat recovery and dehumidification system on the recovery of waste heat from data centers. The proposed system uses desiccant-coated heat exchangers to harvest waste heat and utilize it for the dehumidification of fresh air, thus enabling local consumption of the recovered waste heat. The study focuses on a liquid-cooled data center at a research institute in Shanghai as the experimental subject. The performance of the waste heat recovery and dehumidification system was evaluated through a series of tests. Results show that the system is capable of recovering waste heat at 50℃ from the liquid-cooled data center to continuously dehumidify fresh air. The average coefficient of performance (COP) for dehumidification reaches 8.85. Furthermore, at an airflow rate of 4500 m³/h and a dehumidification duration time of 6 minutes, the average waste heat recovery efficiency achieves 41.94%.

Biogas is an important renewable energy source, produced from organic matter, which has no net carbon emissions from a life cycle perspective. The development of biogas is an important way to alleviate China's natural gas supply shortage. However, the CO₂ content in biogas is generally higher than 20%, which poses negatively impacts on the calorific value, storage and transportation of biogas. Biogas liquefaction after CO₂ removal to produce LNG can significantly improve the calorific value of biogas and facilitate its storage and transportation. This study proposes an integrated process of cryogenic CO₂ removal under supercritical pressure and liquefaction for biogas to address the challenges in existing cryogenic CO₂ removal technology: the risk of freeze blockage in distillation and the high energy consumption associated with low-pressure de-sublimation. The de-sublimation of biogas under critical pressure not only facilitates the effective separation of CO₂ and CH₄, but also reduces the energy consumption of the subsequent methane liquefaction process. The proposed process is modeled in HYSYS and optimized by genetic algorithm coded in MATLAB. The results show that when biogas is cooled to -131℃ at 8.5 MPa, CO₂ can be removed to 0.5% by supercritical de-sublimation. As the CO₂ content increases, the specific power consumption and exergy efficiency of the system increases gradually. When the CO₂ content is between 10% and 30%, the specific power consumption of the system is 0.5295—0.6149 kWh/kg LNG, with the exergy efficiency reaching 57.5%—62.1%. Compared with CO₂ removal processes based on dual-pressure distillation, chemical absorption, low-pressure de-sublimation, the specific power consumption is reduced by over 60% with only 11.9% reduction in LNG density. The considerable reduction in power consumption implies that this study presents a novel approach for high-efficient LNG production from biogas, which holds significant implications for promoting economically viable biogas-to-LNG conversion.

Based on the printed circuit heat exchanger (PCHE), a three-dimensional distributed parameter model was developed, utilizing a three-dimensional array to delineate the heat exchanger core and segment the control units. A method employing a vector matrix for flow path description was introduced. Correlations for heat transfer and pressure drop, pertinent to both the natural gas and water sides of PCHEs, were gathered and summarized from publicly accessible literature, subsequently applied to the simulation model. The governing equations for the model were formulated, alongside a swift iterative algorithm for solving the energy equation, leveraging the bisection method. A performance simulation of an aftercooler for a natural gas compressor on an offshore platform was conducted, yielding parameters such as heat load and flow path pressure drop within the heat exchanger. The model's accuracy was validated by comparing its results with on-site production data. The findings indicate that the simulation model calculates heat transfer with an average error of less than 5% and predicts an average pressure drop error of less than 10% on the natural gas side.

The volumetric expanders play crucial roles in applications such as the organic Rankine cycle, compressed air energy storage, and other related systems. When facing high expansion ratios, multistage expansion becomes necessary. This paper establishes an analysis model for the Wankel expander, taking into account the operation of three working chambers, and simulates expanders connected in series. The simulation results indicate that by appropriately selecting the volume and rotational speed ratio of the expander, one can achieve a maximum power density increase of 66% and an output power increase of 47%. Across a broader range of pressure ratios, the mass flow rate of two-stage series expanders remains relatively stable. When compared to a single expander, operating at a designed or higher expansion ratio results in a power density increase of at least 15%, suggesting that series-connected expanders are well-suited for scenarios with large and fluctuating expansion ratios.

In order to solve the problem of low energy storage and release efficiency, and to decrease both supercooling and superheat of heat exchangers due to large supercooling of ice, the preparation of phase change materials with low supercooling is a hotspot recently. It is an efficient solution to encapsulate n-tetradecane in a stable polystyrene shell. Based on our previous study on types and concentrations of crosslinking agents, the effects of hydrophilic-lipophilic balance of compound emulsifiers and reacting temperatures on the morphology and properties of phase change microcapsules were explored. The results show that when the reacting temperature was 60℃, the particle size increased from 2.735 μm to 24.690 μm with the increase of hydrophilic-lipophilic balance from 16.50 to 40.00. When the hydrophilic-lipophilic balance was 26.50, the particle size increased from 2.735 μm to 23.491 μm with the increase of reacting temperature from 60℃ to 80℃. And the surface morphologies of all m-PCMs was smooth. All the results showed that the microcapsules could provide the best thermal performance (148.12 J/g) and the smallest particle size (2.735 μm), when the concentration of the compound crosslinker was 1.0%, the emulsifier hydrophilic-lipophilic balance value was 26.50 and the reaction temperature was 60℃.

Liquid hydrogen receiving terminal (LHRT) is exposed to great hydrogen-leakage threat due to the frequent operation and complex components. The evaluation of the consequences resulting from a potential liquid hydrogen leakage is therefore essential. Numerical simulation of liquid hydrogen leakage based on a pseudo-source model was conducted at the operational Kobe LHRT in Japan. The effects of leakage apertures and wind speed and direction on the consequences of accidents under the current station structure were assessed in terms of both dispersion and explosive overpressure hazards. The results show that larger leakage apertures, lower wind speeds and the presence of larger obstacles in the downwind direction all cause the hydrogen cloud to build up to a larger volume and produce a larger peak explosive overpressure. The maximum explosive overpressures are all above 0.13790 bar, which would cause moderate damage to the building and moderate injury to personnel. The overpressures in the control room are all below 0.06895 bar and within safe limits.

At present, the international community demand for environmentally friendly working fluids is more and more big, but their use is limited due to their flammability. This study experimentally tested the inhibition effect of R227ea on the flammability of environmentally friendly working fluid R290. It was found that as the proportion of R227ea increased, the lower flammability limit of the mixture gradually increased, and the upper flammability limit first increased and then decreased. The critical inhibitory ratio of R227ea on the flammability of R290 was 3.35. Considering the strong greenhouse effect of R227ea, this study proposed to add environmentally friendly R1216 to R227ea to form a new hybrid flame retardant, thereby achieving“complementary advantages”in their performance. The new mixed flame retardant has a large unit volume cooling capacity compared to R227ea, higher cooling coefficient and thermal conductivity compared to R1216, and lower viscosity. By comparing the performance of ternary mixed refrigerant R290/R227ea/R1216 with pure refrigerant R290, it was found that when the composition ratio of R290/R227ea/R1216 is 21%/6%/73%, its coefficient of performance and unit volume cooling capacity were 103.8% and 94.2% of pure R290, respectively, and its environmental friendliness and flammability meet the requirements. The research results have reference significance for the safe application of R290 and the study of new hybrid flame retardant.