最新刊期
卷 40 ， 期 4 ， 2019
- 摘要：The performance of gas-pump-driven free-cooling unit for heat dissipation was analyzed in a small data center in Beijing. The operating characteristics of the unit were fitted to its operating curve. The results show that the heat exchange capacity of the unit increases with the increase in the difference between the indoor and outdoor temperatures. When the indoor and outdoor temperature difference was 11 °C, the heat exchange capacity was approximately 10.4 kW, and when the difference reached 23 °C, the heat exchange capacity was approximately 13.6 kW. The difference between indoor and outdoor temperatures is the main factor affecting the heat exchange capacity of the unit. The power of the gas pump decreases with the increase in the temperature difference. For differences of 11 °C and 23 °C, the power of gas pump was 1300 W and 810 W, respectively. When the outdoor temperature was ?3.7 °C, the heat exchange capacity of the unit was 13.6 kW, and the EER reached 10.40. When the outdoor temperature was lower than 15 °C, the gas-pump-driven free-cooling unit could meet the cooling load of the data center. Compared with the original air conditioning, the electricity power was reduced by 6842.24 kW?h, and its annual energy saving rate was 25.78%.关键词：data center;gas pump;free cooling;energy efficiency ratio5596|2205|3发布时间：2024-07-18
- 摘要：To investigate the effect of deposited dust particles on the long-term performance degradation of outdoor air-conditioner units, acceleration experiments on dust deposition were carried out in the present study. An acceleration-experiment method for short-term dust deposition with high dust concentration was proposed to simulate the actual long-term dust deposition with low dust concentration, and an experimental rig was established to perform the accelerating-dust test. Acceleration experiments for 2–10 h were carried out on three types of heat-exchanger samples with different fin structures and tube row numbers, and the test results were used to predict the long-term performance degradation of outdoor heat exchangers operated for one to five years. The results show that after five years of operation, the air-side pressure drops of a one-tube wavy fin-and-tube heat exchanger, a two-tube wavy fin-and-tube heat exchanger, and a two-tube plate fin-and-tube heat exchanger were increased by 21.8%, 29.5%, and 25.0%, respectively. Meanwhile, the air-side heat-transfer capacity was reduced by 11.2%, 19.3%, and 18.0%, respectively.关键词：heat exchanger;dust deposition;performance degradation;accelerated experiment;air-side pressure drop;heat transfer capacity5669|2103|3发布时间：2024-07-18
- 摘要：To improve the performance of an air-source heat pump system under large temperature difference conditions, this paper proposed a triple-loop air-source heat pump system scheme. An energy recovery performance test platform was set up according to the exhaust energy recovery in a public building air-conditioning system. The performances of the single- and triple-loop heat-pump systems were tested through experiments under different outdoor-temperature conditions in winter and summer. The results show that the overall performance of the triple-loop system was significantly higher than that of the single-loop system under all operating conditions. With the increase in the indoor and outdoor temperature difference, the triple-loop heat pump system could significantly minimize the problems of excessive compression ratio and system performance degradation of the traditional air-source heat pump. Under winter conditions, the increase rate of the coefficient of performance (COP) of the triple-loop system reached up to 1.88. When the indoor and outdoor temperature difference was 40 ℃, the COP of the triple-loop system was 54.8% higher than that of the single-loop system. Under summer conditions, the increase rate of the COP of the triple-loop system reached 89.8%. When the indoor and outdoor temperature difference was 13 ℃, the COP of the triple-loop system was 74.6% higher than that of the single-loop system.关键词：air source heat pump;exhaust heat recovery;triple-loop system;COP5505|1942|0发布时间：2024-07-18
- 摘要：This study explores the energy consumption during the defrosting process of a cascade air-source heat pump with phase-change energy storage for defrosting and from where it comes. Experiments are carried out at an outdoor temperature of ?9 ℃, relative humidity of 85%, and frosting volume of 1.5 kg. The experimental results show that the defrosting energy is mainly used in melting the frost layer, vaporizing the retained water, heating the fins and coils of evaporator, heat transfer with the ambient air, and heating the melted water. The proportion of each part is 15.7%, 15.0%, 23.4%, 38.0%, and 7.9%, respectively. During the defrosting, the defrosting energy mainly comes from the heat released from the thermal accumulator to the lower pressure stage, heat stored in the system before defrosting, and heat provided by the compressor at lower pressure stage. The proportion of each source is 45.2%, 30.4%, and 24.4%, respectively.关键词：defrosting energy consumption;air-source heat pump;cascade cycle;thermal accumulator5551|2250|2发布时间：2024-07-18
- 摘要：The thermal performance of a traditional transcritical CO2 heat pump for space heating in winter can be improved by mechanical subcooling using a simple vapor-compression cycle. A thermodynamic model is developed in this study to analyze the operating characteristic of a CO2 heat pump system for space heating using mechanical subcooling. The results indicate that a maximum coefficient of performance (COP) exists at optimum discharge pressure and subcooling degree. The COP improves by 15.9% under a standard working condition compared with that in the traditional CO2 heat pump. This system can effectively solve the problem of rapid COP deterioration at a relatively high return water temperature. The COP of the CO2 heat pump that employs mechanical subcooling only decreases by 8.4% as the return water temperature increases from 40 to 50 ℃, whereas that of the traditional CO2 system decreases by as high as 16.9%. Moreover, the discharge pressure and temperature can be effectively reduced. The advantage in the pressure reduction is more pronounced at lower return water temperature. The overall energy efficiency of the heat-pump system is influenced by the selection of the working fluid used in the mechanical subcooling cycle. Ammonia (R717) achieves the highest energy efficiency among the 11 samples, and the lowest energy efficiency is realized in the use of R1234yf refrigerant. The thermal performance more significantly improves at low ambient temperature. Furthermore, the scale of the mechanical subcooling cycle that uses a traditional refrigerant is relatively small compared with that of the CO2 heat pump system. Employing the mechanical subcooling method is an economical solution to improve the overall thermal performance of a transcritical CO2 heat pump for space heating.关键词：heat pump;CO2;mechanical subcooling;transcritical;space heating5588|1970|8发布时间：2024-07-18
- 摘要：Air-source heat pumps suffer from many problems such as high pressure ratio, high discharge temperature, and poor performance at low temperature. The enhanced vapor injection (EVI) technology can improve the performance of an air-source heat pump at low temperature. This study sets up a numerical simulation model of an air-source heat pump system to investigate with the effect of EVI. A test bed is designed to verify the simulation model. The performance of the air-source heat pump with EVI is simulated based on the model. The results demonstrate that an optimal relative vapor-injection mass exists that achieves the highest system energy efficiency. The best range of relative vapor-injection mass is 8%–10% for the best heating performance when the environment temperature is lower than ?6 ℃. The best range of relative vapor-injection mass is 5%–8% when the environment temperature is from ?6 to 0 ℃. The best range of relative vapor-injection mass is 4%–5% when the environment temperature is higher than 0 ℃. The corresponding optimal relative vapor-injection pressure is between 0.7 and 0.9. The heating capacity increases by 33%, and the coefficient of performance increases by 31% under optimal air-injection parameters.关键词：air-source heat pump;enhanced vapor injection(EVI);vapor injection mass;numerical simulation5689|2928|3发布时间：2024-07-18
- 摘要：To obtain the applicability and operation superiority of the solar-air source heat pump hot water system in different regions, the operation performance and energy efficiency coefficient of the air source heat pump unit and solar collector unit were tested through experiments under typical conditions. Tianjin, Shanghai, Guangzhou, and Kunming were selected for cold, hot-summer and cold-winter, hot-summer and warm-winter, and temperate regions, respectively. With the consideration of Chinese habits on domestic hot water, the performance of the heat pump system was analyzed in different areas for a typical family with 3~5 persons. The annual performance factor (APF) of a hot water system in different regions is calculated based on the weighted annual meteorological data of different cities. It is concluded that the APF of the hot water system is 3.03, 3.34, 3.79, and 3.28 in cold, hot-summer and cold-winter, hot-summer and warm-winter, and temperate regions, respectively, and the annual contribution rate of solar energy in the four regions is 29.82%, 32.07%, 29.58%, and 38.62%, respectively. The APF of the combination system can reach 3.67, 4.06, 4.39, and 4.45, respectively.关键词：air source heat pump;solar collector;hot water system;APF;different climate zones5528|2137|3发布时间：2024-07-18
- 摘要：Heat-driven absorption refrigeration technology is an important approach for solar-energy utilization and industrial-waste heat recovery. Among them, the generation and absorption heat exchange (GAX) absorption cycle exhibits a high efficiency whose coefficient of performance (COP) can vary with the heat-source temperature. This paper proposes the use of an ionic liquid–water working pair without crystallization risk for the GAX absorption cycle. The NRTL model is utilized to calculate the thermal physical properties of the ionic liquid–water working pair, and the performance of the GAX absorption refrigeration cycle is calculated based on the working-pair properties. The results showed that the [DMIM][DMP]/water solution can be used in the GAX absorption cycle and achieves a COP of 1.02, which is 27.5% higher than that in a single-effect cycle. In addition, the results show that the ionic liquid–water absorption cycle achieves better performance than the LiBr–water absorption cycle.关键词：refrigeration;GAX absorption cycle;NRTL model;ionic liquid5671|1956|2发布时间：2024-07-18
- 摘要：Data center is a space for central placement and setting of data-processing equipment. It contains abundant low-temperature waste-heat resources. If a silica–water adsorption refrigeration unit is used in the data center for waste heat recovery, the cooling capacity of the refrigeration unit can satisfy the requirements of directly cooling the server CPU and the demand of the water-cooled backboard. The temperature of the heat exchange fluid under different working conditions is measured. The results show that the silica gel–water adsorption chiller can effectively utilize a low-temperature heat source in the range from 45 to 60 ℃ to cool the chilled water from approximately 23 ℃ to below 20 ℃. The cooling capacity is between 1.28 and 4.01 kW, and the coefficient of performance ranges from 0.22 to 0.51. When the hot-water temperature is increased, the cooling-water temperature is reduced, and the temperature of the chilled water is moderately increased. The silica gel–water adsorption chiller can provide more cooling capacity, and the data center can achieve better energy saving results.关键词：adsorption refrigeration;adsorbent;data center;waste heat refrigeration5653|2530|3发布时间：2024-07-18
- 摘要：Based on the ?-NTU method, a heat- and mass-transfer model of a cross-flow heat-source tower was established, and the transient simulation of the model was performed using the TRNSYS simulation platform. Then, the dynamic and static characteristics of the model were validated using experimental data under different conditions. The results showed that for the outlet temperature of a heat-source tower, the static relative error was controlled within 4%, and the dynamic relative error was less than 6%. For the latent heat transfer rate, the static error was less than 5 kW. Therefore, the model can ensure high accuracy while reducing calculation complexity. As the number of working fans increased, the total heat transfer rate increased from 780 to 1060 kW, and the latent heat transfer rate increased from 317 to 433 kW. The proportion of the latent heat transfer was not affected. As the temperature of the solution that entered the tower fell from ?2.85 to ?9.09 ℃, the latent heat transfer rate of the heat source tower increased from 165 to 227 kW, and the proportion of the latent heat transfer decreased from 42% to 31%. The latent heat transfer rate gradually increased with the decrease in the solution temperature. As the flow rate of the solution decreased from 260 to 100 m3/h, the heat absorption efficiency increased from 0.26 to 0.44. The solution flow rate exerted the greatest effect on the heat absorption efficiency among all operatin g parameters. To reduce energy consumption, attention should be given to the reduction control of the solution flow under a partial-load condition.关键词：heat-source tower;heat transfer;mass transfer;simulation;NTU5525|1988|3发布时间：2024-07-18
- 摘要：The simulation accuracy of the thermophysical properties of gas-liquid equilibrium of a single refrigerant based on a conductor-like screening model for real solvent (COSMO-RS) is investigated in this work. The research results show that in order to improve the simulation accuracy, the scale factor of the surface area of the molecules needs to be adjusted. A single refrigerant is divided into inorganic substances, hydrocarbons, and HFCs. The simulation results under an optimum scale factor are compared with the values from NIST. The relative errors for CO2 and NH3 in inorganic matters are less than ±3% and ±1%, respectively. The relative error for the hydrocarbon refrigerant is within ±3%, and that for HFCs is not more than ±2%. Then the rule of the scale factor of the molecules is studied and the saturated vapor-pressure equation of a single refrigerant is fitted. Therefore, COSMO-RS can predict the gas–liquid equilibrium of a single refrigerant and provide a method for the gas-liquid equilibrium of new refrigerants.关键词：COSMO-RS;vapor-liquid equilibrium;single refrigerant;HFCs9014|1977|0发布时间：2024-07-18
- 摘要：The current experiment uses de-ionized water as a substance to investigate the influence of a small amount of residual non-condensable gas in a narrow rectangular vertical channel on the condensation heat transfer characteristics. The steam condensation surface heat transfer coefficient is obtained using the thermal resistance separation method, and the influence of non-condensable gas, cooling water mass flow rate, inlet temperature, and effective flux density on the steam condensation surface heat transfer coefficient is analyzed. The main results are as follows. When the heat flux density is 1.668 kW/m2, i.e., the steam mass flow rate is small, a 2% volume of non-condensable gas reduces the condensation surface heat transfer by 33%. However, when the heat flux density is 3.887 kW/m2, i.e., the steam mass flow rate becomes larger, a 2% volume of non-condensable gas only reduces the condensation surface heat transfer by 14%. In addition, the steam condensation surface heat transfer coefficient decreases as the volume percentage of the non-condensable gas increases. It also increases as the cooling water mass flow rate decreases and increases as the inlet temperature and effective flux density increase.关键词：rectangular channel;condensation;non-condensable gas5549|2018|1发布时间：2024-07-18
- 摘要：As an important part of a parallel flow condenser, folded tube has a good ultimate bearing capacity and is expected to gradually replace the conventional extruded tube. This paper presents the mechanism, simulation, and experimental analysis of a folding pipe. The numerical curves of the stress and strain of folded tube materials were obtained by fitting experimental data. The material parameters were imported into ANSYS to develop a simulation model of folded tube blasting. The simulated blasting value of this model was consistent with the experimental blasting value of 21.9 MPa. According to the theoretical analysis of the folding tube, a type of interpolation of a double folded new microchannel plate finned tube was designed, and a simulation model was established to analyze its internal and external wall-thickness parameters such as the effect on the bearing-capacity limit. We conclude that at a wall thickness of 0.08 mm, an outside wall thickness of 0.2 mm, and in the 19th hole, optimal comprehensive performance was achieved. The new folding tube volume decreased by 35% and the ultimate bearing capacity value increased by 30% compared with those of an ordinary microchannel tube. The new folding tube not only can save material cost and make the flat tube structure more compact but also has an excellent ultimate bearing capacity.关键词：parallel flow porous aluminum tube;numerical simulation;folding tube;finite element analysis;condenser5636|2115|1发布时间：2024-07-18
- 摘要：The hysteresis or overshoot in a variable refrigerant flow (VRF) system control is studied. This study considers a variable-frequency rolling rotor refrigeration system as the research object. By changing the compressor frequency and opening of the electronic expansion valve, a curve fitting model under a separate control of the two processes was established. An experimental research on the synchronous control method of the two processes under different working conditions was carried out. The results show that the superheat decreased with the opening of the electronic expansion valve. When the electronic expansion valve opening was 28%–32% and the frequency was 44.5–46.5 Hz, the degree of superheat control became more difficult. This condition could be improved by adjusting the temperature of the chilled water. Under certain conditions, the relationship between the frequency and opening of the electronic expansion valve could be obtained by controlling the mass flow. Synchronous control of the opening degree of the electronic expansion valve and compressor frequency was achieved; thus, the system could quickly reach a stable state.关键词：compressor;electronic expansion valve;frequency;opening;control5788|2197|3发布时间：2024-07-18
- 摘要：The performance of a refrigeration system is affected by many factors, and cooling fan is one of the important factors. The distributor directly influences the heat transfer performance of the cooling fan, such as the iso-dryness and equal-flow distribution of refrigerant. In this experiment, a new type of premixed nozzle shunt (A) is designed, and a test bench is built to test the shunt performance. Improving the efficiency of the refrigeration system and saving energy are certainly significant. An R22 refrigerant was used in the experiment, and the design condition was a cold storage temperature of ?18 ℃. Experiments were carried out at 0, ?4, ?8, ?12, ?16, ?18, and ?20 ℃ (cold storage temperature). The test results were compared with another nozzle shunt (B), gas–liquid separation shunt (C), CAL shunt (D), and Venturi shunt (E). The comprehensive performance of the shunts followed the order from good to bad, i.e., A > B > C > D > E. The overheat, inhomogeneity, heat transfer coefficient, and cooling capacity of A were better than those of the others. Adopting the A shunt reduced the fan heat transfer temperature difference and irreversible loss and improved the system performance.关键词：premixed nozzle shunt;unevenness;premixing;air cooler5683|1993|0发布时间：2024-07-18
- 摘要：A new scheme using a separate heat pipe combined with the evaporator of a direct-cooling refrigerator is proposed. For a given heat sink temperature (?25 ℃) and different heat source temperatures (5, 8, and 12 ℃), the heat transfer rate of the separate heat pipe is tested. The result shows that the optimum filling amount is 120 g. Then, variation in the internal parameters of the system are studied and analyzed based on the cooling process. The experimental results show that after starting for approximately 10 min, the internal parameters of the separate heat pipe reaches a relatively stable state. The use of the separate heat pipe can reduce the temperature in the fresh food compartment from 16 to 5 ℃ in 60 min, which can satisfy the mid-range temperature requirements of a typical refrigerator. Meanwhile, it can also reduce the temperature in the fresh food compartment to 0 ℃ in approximately 135 min. Through automatic control of the solenoid valve, the temperature in the fresh food compartment can be maintained at 8 ℃, and the temperature fluctuation reaches to within 1.1 ℃, which is better than the 2.5 ℃ temperature of a direct-cooling refrigerator. In a on–off cycle, the running and stopping times of the separate heat pipe are approximately 6.5 and 42.8 min, respectively, indicating that the on–off ratio is approximately 15.2%. The good heat transfer characteristics and temperature control capabilities can meet the requirements of a new cool-storage refrigerator.关键词：heat pipe;heat transfer performance;refrigerator;temperature control performance;refrigerant5982|2184|0发布时间：2024-07-18
- 摘要：Regenerative evaporative cooling is one of the main forms of dew point evaporative cooling. Regenerative evaporative cooling can cool the air below the wet bulb temperature without changing the humidity of air. An experimental system is established in this study, and an experimental research on the cooling capacity of regenerative evaporative cooling under different environmental conditions is carried out. The effects of fresh air temperature, humidity, speed, and water supply temperature on the system performance are analyzed. The experimental results show that the system provides a good cooling effect under the conditions of high temperature and low humidity. At an ambient temperature of 31 ℃, the temperature drop is 5.6 ℃ at a relative humidity of 31.5%, whereas the temperature drop is only 3.4 ℃ at a relative humidity of 60%. Reducing the temperature of the water supply can improve the cooling efficiency of the system. By setting the fresh air temperature at 35 ℃ and ?the relative humidity at 60%, the temperature drop between the inlet and outlet when the water temperature is 13 ℃ is 6.5 ℃. When the water temperature is 31 ℃, the temperature drop between the inlet and outlet is only 3.3 ℃.关键词：regenerative evaporative cooling;experimental research;relative humidity;supply water temperature5557|1928|2发布时间：2024-07-18
- 摘要：A fault diagnosis model may be degraded or may fluctuate in an on-site refrigeration system. Thus, the model needs to adaptively learn the on-site data. To learn the online data stream of a refrigeration system during fault diagnosis, an adaptive diagnosis model is developed using the accurate threshold-based concept drift detection mechanism and an incremental support vector machine algorithm, which are applied to re-learn the refrigerant overcharge failure. Using two optimization processes to select and filter the data information, the algorithm retains the original diagnostic knowledge and only learns the unknown sample data information, which can greatly save training time and quickly adapt to a new environment. Simulation experiments are performed for online learning of the diagnosis of the refrigerant overcharge failure. The results show that when a new type of fault occurs, the diagnostic model detects the concept drift and then updates itself through incremental learning to learn and diagnose new faults. Three concept drifts are detected, and the diagnosis model only needs to update three times to realize learning of the refrigerant overcharge failure, that is, the diagnostic model only learns 600 of the 1400 refrigerant overcharge failure samples and ensures that the ultimate diagnosis model achieves better diagnostic performance for subsequent data streams with the correct rate reaching over 99%. In terms of on-site refrigeration system fault diagnosis application, the re-learning and self-adaptation of the diagnostic model shows good application potential.关键词：fault diagnosis;concept drift;incremental Support Vector Machine;refrigeration system;adaptive learning4131|2023|1发布时间：2024-07-18
- 摘要：The heat transfer performance of two types of doubly enhanced tubes was experimentally studied using R245fa after the horizontal single-tube falling film evaporating test bench was built. The Wilson–Gnielinski graphic method was proposed to obtain the surface heat transfer coefficient of the tubes. The effect of the wall structure on the heat transfer performance was analyzed. The heat transfer correlations inside and outside the tubes were provided, and a fitting optimization scheme was proposed. The results showed that the enhancement rates of in-tube and out-tube heat transfer of the Y tube were 2.12–2.94 and 2.27–5.54, respectively. The internal and external enhancement rates of the T tube were 2.48–2.98 and 2.58–3.00, respectively. The out-tube heat transfer performance of the Y tube and the in-tube heat transfer performance of T tube were better. The heat transfer performance of the Y tube can be reinforced by optimizing its in-tube structure. The best spraying density of the Y tube [0.14–0.18 kg/(m?s)] was higher than that of the T tube [approximately 0.10 kg/(m?s)]. The surface heat transfer coefficient of the two tubes first increased and then decreased with the increase in the heat flux. However, the surface heat transfer coefficient of the Y tube changed more rapidly, which indicated that the thermosyphon boiling phenomenon caused by the smaller fin pitch of the Y tube accelerated the evaporation of refrigerant. The surface heat transfer coefficient of the two tubes increased with the increase in the evaporation temperature.关键词：coefficient of heat transfer;improved Wilson graphic method;falling film;enhanced tube;refrigeration5625|2021|1发布时间：2024-07-18
- 摘要：The air temperature in a subway tunnel is influenced by the surrounding rocks. The temperature distribution in the surrounding rock is affected by many factors. To obtain the evolution trend of the heat transfer and thermal reservoir of the surrounding rocks, we need to understand the influence of various factors on the heat transfer. In this study, the CHAMPS-BES software is used to simulate the effect of the soil property and air temperature on the heat transfer in the surrounding rocks and the significant degree of influence of various factors on the temperature distribution characteristics in the surrounding rocks using an orthogonal experimental method. We find that the influence of the soil thermal diffusivity on the peak position of the surrounding rocks is very significant. When the soil thermal diffusivity is 7.6 × 10-7 m2/℃, the heat transfer is faster, and the thickness of the heat sink for 20 years exceeds the range of 50 m. On the basis of this research, the study on the characteristics of heat storage and change of the heat storage in the surrounding rocks in different regions reveals that the soil in north area has lower initial temperature, and the annual net heat storage of the soil is greater. In the Harbin area, the annual net heat storage of the soil is approximately 102300 MJ, which is equivalent to 1.8% of the train heat dissipation. However, the annual net heat capacity of the soil gradually decreases with the increase in the operation years.关键词：subway tunnel;surrounding rock and soil;thermal storage;orthogonal test;soil thermal diffusivity3994|2119|1发布时间：2024-07-18
- 摘要：In this study, an electric-heating film was set up in a climate chamber to simulate the heat transfer in an external building envelope. Then, the indoor air distribution characteristics in a room with chilled ceiling and mixed ventilation were studied when the cooling loads were 83 or 111 W/m2. The results show that a uniform vertical temperature profile below 1.7 m as well as a non-uniform temperature profile above 1.7 m existed when the ceiling surface temperatures varied from 15 to 23 ℃ and the supply air temperature was 22 ℃. The CO2 concentration was large in the occupied zone and small near the ceiling or floor. Moreover, the average vertical air temperature difference, turbulence intensity, and contaminant removal effectiveness were 0.1–0.2 ℃, 32%–38% and 0.62–0.86, respectively. Therefore, the changes in the ceiling surface temperature slightly affected the vertical air-temperature difference and turbulence intensity, whereas they clearly influenced the contaminant removal effectiveness.关键词：chilled ceiling;mixed ventilation;vertical air temperature difference;turbulence intensity;contaminant removal effectiveness3973|1965|1发布时间：2024-07-18
- 摘要：To address the wrong distribution of refrigerants in multi-path heat exchangers in air conditioners, a distributor, which is capable of evenly dividing a two-phase refrigerant, is proposed and tested using a visual experiment. The principle of the distributor design is to form an annular flow and then evenly allocate it. The detailed development method includes a calculation model for inlet tube geometries of the distributor to form an annular flow and a design method for the connection structure between the inlet and outlet tubes to uniformly distribute the annular flow. The experimental results show that when the mass flow rate is between 14 and 22 g/s, the distribution unevenness values of the novel distributor at the horizontal, sloped, and vertical installations are 10%–24%, 14%–27%, and 24%–47%, respectively, which are lower than those of the conventional cone-type distributor, indicating much better performance of the proposed distributor.关键词：air conditioner;distributor;gas-fluid two-phase flow regime;annular flow5556|2099|1发布时间：2024-07-18
- 摘要：The working life and reliability of power battery is very important to the electric vehicle. Based on the way of liquid cooling, a set of simple of heat management unit for power battery is designed and developed, and the feasibility of the scheme is confirmed by software simulation, laboratory test and vehicle loading test. The study shows that the air-conditioning wind and environmental wind of the bus can be cooled to the cryogenic heat exchanger in summer and the two quarter of spring and autumn, which can match the requirements of the power battery to the refrigeration capacity in different environments. Under the two conditions of laboratory and vehicle loading, the refrigerating capacity of the unit under the design condition is more than 2.5 kW, and the error between the actual power and the set power is less than 2% when the unit is heated by PTC. When the unit is loaded, the length of the intake tube is less than 2 m and the number of the 90°bend of the wind pipe is less than 2, the heat exchange still satisfies the design requirements. The guide plate of the inlet air is also optimized, the air inlet can be evenly distributed on the surface of the low temperature heat exchanger when the angle of the guide plate is 73°.关键词：thermal management;power battery;liquid cooling;experimental research5933|2268|0发布时间：2024-07-18
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