最新刊期
卷 42 ， 期 1 ， 2021
- 摘要：Electrocaloric cooling technology has advanced with the discovery of the giant electrocaloric effect, employing the entropy change during the poling and de-poling processes to enable operation of the refrigeration cycle. Electrocaloric refrigeration involves solid-state working bodies, without any greenhouse gas; thus, it is believed to be environmentally benign. The solid-state phase transition in the working bodies is directly induced by electricity, without any secondary energy transition, whereby a high energy efficiency and structural simplicity are achieved. These advantages enable provision of thermal management for micro-systems. After more than a decade of development, a large electrocaloric effect has been observed in many material systems such as ferroelectric ceramics, single crystals, polymers, and dielectric fluids. Several technical advances have been made in electrocaloric thermodynamic cycles and cooling device prototypes. This review article introduces the development status and the latest progress in electrocaloric refrigeration technology from three standpoints: the thermodynamic principle of the electrocaloric effect, the electrocaloric material, and the development and simulation of electrocaloric refrigeration devices. This article also discusses the opportunities and challenges faced in the field of electrocaloric refrigeration technology. The state-of-the-art electrocaloric refrigeration comprises an adiabatic temperature change of the material of 40–50 K, an irreversible loss of the working body of less than 10%, a theoretical thermodynamic perfection of 40%–60%, and a temperature span of the prototype of 14 K. Future advances in the field depend on the synergic development in the phase transition theory in condensed matter, the synthesis of new materials, material integration processes, a mass and heat transfer across the solid-state interfaces, and solid-state thermodynamic theory. Only when the above key development is achieved can one realize the possible advantages of electrocaloric refrigeration in micro-cooling systems, which may eventually provide solutions to aid on-chip cooling, battery thermal management, and many other technological aspects that require highly efficient, light-weighted, compact, and point-of-care thermal management.关键词：electrocaloric effect;solid state refrigeration technology;ferroelectrics and relaxors;dielectrics;thermal management technology3012|2723|6更新时间：2025-09-03
- 摘要：Geothermal energy is widely used in building heating owing to its stability, large reserves, and wide distribution. Beginning from the classification of geothermal energy heating technology, this paper elaborates on the basic concepts, development history, and application status of shallow ground source heat pump technology, hydrothermal heating technology, and medium-deep borehole heat exchanger heating technology. Based on the reported research, future directions for investigation of geothermal energy heating technology are summarized, from the perspective of the operation mechanism and application practice. These future research directions mainly include heat balance analysis of large-scale shallow borehole heat exchanger arrays, high-efficiency water recharge technology of hydrothermal heating, and evaluation of the heat transfer performance of medium and deep borehole heat exchanger arrays.关键词：geothermal heat pump;heating technology;borehole heat exchanger;thermal balance;performance optimization1998|2106|19更新时间：2025-09-03
- 摘要：The non-uniform distribution of two-phase flow usually happens in a microchannel heat exchanger, which significantly reduces the performance of the microchannel heat exchanger. In this paper, research on the two-phase flow distribution in a microchannel heat exchanger is summarized and analyzed, with focus on the factors affecting the two-phase flow distribution characteristics in a microchannel heat exchanger, techniques to improve the distribution uniformity of a two-phase flow, simulation studies on a two-phase flow distribution of a microchannel heat exchanger, and applications of phase separation technology in microchannel heat exchangers. Finally, the research status and future direction of a two-phase flow in a microchannel heat exchanger is discussed关键词：microchannel heat exchanger;two-phase flow distribution;distribution uniformity;correlations;phase separation1869|1970|5更新时间：2025-09-03
- 摘要：To exhaust the ammonia gas released after the rupture of a low-pressure suction pipe of an ammonia refrigeration compressor, a computational fluid dynamics (CFD) method was used to numerically calculate the accident ventilation process and compare the emergency ventilation effectiveness under different airflow patterns in this study. According to the calculation results, the upper edge of the exhaust vent in the side wall has little effect on the removal of pollutants within the range of 0–0.2 m. When there are doors at both ends of the ammonia refrigeration plant, and there are upper and lower rows of windows in the middle, , the volume of the area where the NH3 mass fraction exceeds 4.2 × 10-4 after 120 s of emergency ventilation is: 133.0% higher with all doors open, 60.7% higher with all doors and windows open, 98.1% lower with the upper row of windows open, and 180.3% higher with the lower row of windows open respectively than that with all open windows. The total indoor NH3 mass after 120 s of ventilation is 40.6% higher with all doors open, 12.7% higher with all windows and doors open, 24.1% lower when the upper row of windows are open, and 44.4% higher when the lower row of windows are opened than that with all windows open.关键词：refrigeration room;leakage;computational fluid dynamics;obstacles;emergency ventilation;air flow pattern1598|1868|3更新时间：2025-09-03
- 摘要：With the rapid development of big data and intelligence, data have played a decisive role in studies on air conditioning, and possession of good data management models appears to be extremely important. This article proposes, for the first time, a sharing scheme of electronic medical records for air-conditioning products using blockchain as the underlying technology, aiming to build a decentralized system that third-party trust can be omitted in an air-conditioning medical record information sharing platform. Through the use of hashing computing, asymmetric encryption, and a complete network consensus and other technologies, the air-conditioning fault record data of the entire network trustworthiness were achieved, breaking the trust barriers between individuals and enterprises. Research shows that the platform of electronic medical records for air-conditioning products based on blockchain technology can endow the data stored in it with the characteristics of immutability, relative transparency, and traceability to ensure complete credibility of the platform data. At the same time, its storage cost is relatively low, with an average storage cost of only 2 kB per case, which presents significant application prospects.关键词：electronic medical records for air-conditioning products;data storage;consensus algorithm1477|1824|0更新时间：2025-09-03
- 摘要：To investigate the heating performance of an electric vehicle heat pump air conditioning system at low temperature, an experimental platform for the air source heat pump air conditioning system was set up in this study to experimentally determine the heating performance of an electric vehicle heat pump air conditioning system with ambient temperature of ?10 ℃ to 0 ℃. The influences of the compressor speed (2 000–5 000 r/min), air inlet volume (300–400 m3/h), and ambient temperature on the performance of the system were analyzed. Finally, a formula was derived to estimate the range of the electric vehicle after using the air conditioning system. The results show that with an increase in compressor speed, the compressor discharge pressure and temperature, as well as the heat produced by the compressor, somewhat increase; however, the COP of the system decreases. When the compressor speed and ambient temperature are kept unchanged, the inlet air volume of the air conditioning box increases from 300 m3/h to 400 m3/h, heat production increases by 13.3%–26.0% and the COP increases by 0.03–0.80. Under other constant conditions, when the ambient temperature rises from ?10 ℃ to 0 ℃, the heat produced by the heat pump air-conditioning system increases by 60.9%–71.0% and the COP increases by 0.51–0.63. According to the formula, when the ambient temperature is ?10 ℃ to 0 ℃, the range of the heat pump air conditioning system can be improved by 13.5%–20.8% compared with the condition of same heating capacity, using a PTC heater.关键词：electric vehicle;heat pump;driving range;heating performance;coefficient of performance1638|1906|0更新时间：2025-09-03
- 摘要：The driving range of pure electric vehicles (PEVs) significantly decreases in winter. In this study, a mathematical model of vehicle driving range considering the heat production of the battery and the load of the air conditioning was established to simulate and analyze the influence of heat pump heating, ambient temperature (AT) and cabin temperature (CT) on the driving range and the vehicle battery during the cold start under three driving conditions, namely, highway fuel economy test (HWFET)、new European driving cycle(NEDC)、China light-duty vehicle test cycle for passenger car (CLTC-P). Compared with the measured data, the simulation and experiment match well. The results show that the driving range decreases gradually with the decrease of AT and the increase of CT under three driving conditions. When the AT is 0 ℃ and the CT is 15 ℃, 20 ℃, and 25 ℃, the driving range of the China CLTC-P standard decreases by 21.46%, 27.74%, and 33.19%, respectively. The influences of three heat distribution strategies on driving range are different during the cold start of PEVs. During the cold start, when all the heat of heat pump is used to heat the battery, the battery power can be recovered properly. Under the driving conditions of NEDC and CLTC-P, the maximum state of charge (SOC) of the battery increases by 1.52% and 2.03% compared with the initial SOC. The driving range can be increased to a certain extent by using the heat pump.关键词：pure electric vehicle;thermal management;heat pump;driving range;battery temperature;cold start1617|2226|1更新时间：2025-09-03
- 摘要：A CO2 two-phase thermosyphon loop (TPTL) system in data centers were investigated in this study. The maximum heat transfer capacity, total thermal resistance, and driving temperature difference were compared between CO2 and R22 TPTLs experimentally. The results indicate that under the same filling ratio, the maximum heat transfer capacity of CO2 TPTL was significantly greater than that of R22 TPTL. When the diameters of the riser and downcomer were 9 mm, the maximum heat transfer capacities of the CO2 and R22 TPTLs were 3 300 W and 1 500 W, respectively. When the diameter was 12 mm, the maximum heat transfer capacity of the CO2 and R22 TPTLs were 5 400 W and 2 200 W, respectively. The study also found that the normal working load range of CO2 TPTL was larger than that of R22 TPTL, but the total thermal resistance of CO2 TPTL was lower than that of R22 TPTL. Under different heat transfer capabilities, the driving temperature difference required for CO2 TPTL was 4 °C lower than that of R22 TPTL on average; that is, the cooling source temperature required by CO2 TPTL can be increased by 4 °C under the same conditions. Taking a small data center as an example, it was calculated that the annual energy consumption of the CO2 TPTL system is 7.425 × 105 kW?h lower than that of the R22 TPTL system and 3.182 × 106 kW?h lower than the central air-conditioning system under the climate conditions in Shanghai. Keywords two-phase thermosyphon loop; CO2; data center; filling ratio关键词：two-phase thermosyphon loop;CO2;data center;filling ratio1674|1890|3更新时间：2025-09-03
- 摘要：A data center cabinet with a built-in evaporator has been proposed to reduce the energy consumption of cooling systems and improve the cooling effect. The influence of the evaporator arrangement and operating parameters on the cooling effect was evaluated by utilizing a simulation model. The results show that the cabinet achieves the best cooling performance when an evaporator is placed in the middle of two rows of servers. The qualified coefficient of temperature is 100%, and the standard deviation and uniformity coefficient are reduced by 66.67% compared to those of the original structure (the evaporator is located under two rows of servers). When the rated air volume reaches 2 000 m3/h, a further increase in the air volume causes a slow improvement on the cooling effect. Within the range of 2 000–2 400 m3/h, the variation between the average and maximum temperatures is approximately 0.5 ℃. When the rated air pressure is 250 Pa, the cooling effect of the cabinet is the highest, and the standard deviation and uniformity coefficient are 0.66 ℃ and 0.016, respectively. As the inlet-air temperature increases from 25 °C to 29 °C, the overall temperature of the server rises, but the temperature uniformity is almost stable. The largest changes in standard deviation and uniformity coefficient are only 0.05 ℃ and 0.002, respectively.关键词：data center cabinet;built-in evaporator;cooling effect;operating parameter1593|1785|1更新时间：2025-09-03
- 摘要：In this study, a low-temperature and low-pressure heat pump drying device was built to explore the drying effect of industrial iron powder at different low pressures and analyze the heat and mass transfer in the low-temperature and low-pressure drying processes. The results show that a decrease in the drying ambient pressure can increase the dehumidification capacity of wet iron powder. When the ambient pressure drops from 101 kPa to 10 kPa, the dehumidification capacity increases by 2.5 times, and the moisture content of iron powder can be reduced to less than 1% at a pressure of 10 kPa. For drying air at 50 °C and 0.5 m/s, the mass and heat transfer coefficient decrease by 28.1% and by 68.4%, respectively, as the pressure decreases from 101 kPa to 10 kPa. Therefore, the Lewis factor, which characterizes the relative intensity of heat and mass transfer, can increase with the ambient pressure decrease. In a drying environment of 10 kPa and 50 °C, the mass and heat transfer coefficient increase by 32.9% and 67.8%, respectively, when the air speed increases from 0.2 m/s to 2 m/s. This indicates that the enhanced effect of air speed on the mass transfer coefficient is inhibited by the low-pressure environment; thus, the Lewis factor increases with the increase in air speed. The Lewis factor is 0.5–0.6 in an environment of 10 kPa, indicating that there are obvious differences between the mass diffusion and heat diffusion in a low-pressure environment.关键词：heat pump;low temperature;low pressure;drying1462|1693|0更新时间：2025-09-03
- 摘要：Frosting is one of the main factors restricting the application of microchannel heat exchangers in refrigeration and air conditioning systems. Aiming at the frosting problem of a microchannel heat exchanger, the frosting mechanism was analyzed based on the phase transformation driving force, and the growth morphology of the frost layer on the cold surface under different environmental factors was observed in this study. The effects of wet air temperature, humidity ratio, air velocity, and coolant temperature on the frosting characteristics, and the heat transfer performance of the microchannel heat exchanger were experimentally studied. The results show that the humidity ratio and air velocity of the wet air are the main factors affecting the frosting of the microchannel heat exchanger. At 15 min of frosting, the amount of frost on the heat exchanger surface under a humidity ratio of 5.75 g/(kg dry air) increased by 63.87% compared with a humidity ratio of 3.58 g/(kg dry air); the amount of frost on the heat exchanger surface under an air velocity of 2.5 m/s increased by 55.4% compared to the air velocity of 1 m/s. With the increase in frosting time, the lower the temperatures of the humid air and coolant, the greater the humidity ratio and air velocity are, and the more obvious the downward trend of the heat exchange capacity is.关键词：frost;heat exchanger;phase transformation driving force;heat exchange capacity;morphology1703|2131|1更新时间：2025-09-03
- 摘要：In this study, a pressure-adjustable closed environment chamber was built, and the effect of different tube rows and circulating hot water temperatures on the characteristics of air-side convective heat transfer for a finned tube condenser at a low-pressure environment of 40–101 kPa were studied. The results show that under the same Reynolds number, the reduction in ambient pressure leads to a reduction in air-side convective heat transfer. When the air-side Reynolds number is 400, the ambient pressure decreases from 101 kPa to 40 kPa, and the convective heat transfer coefficient decreases by 44.1%. As the ambient pressure decreases, the number of tubes has a weaker effect on the air-side convective heat transfer. In a low-pressure environment, changing the heating temperature of the circulating water does not have a significant impact on the heat transfer coefficient. As the ambient pressure decreases, the air-side convective heat transfer coefficient deviates from the calculation results of the normal atmospheric pressure model. As the ambient pressure decreases from 101 kPa to 40 kPa, the average deviation increases from 17.3% to 77.5%. Based on the experiment results, the air-side heat transfer model of the finned tube is modified at normal pressure according to the influence of the ambient pressure and the tube rows on the air-side convective heat transfer.关键词：finned tube condenser;low pressure;convective heat transfer;Reynolds number1529|1734|0更新时间：2025-09-03
- 摘要：Providing healthy air has become an important indicator of air conditioners. In this study, a self-cleaning heat exchanger was designed in a variable refrigerant flow air-conditioning system, and the potential of dedusting and sterilization of the evaporator was investigated experimentally. Firstly, the dust removal and cleaning of the indoor unit were realized by the condensed water generated by the heat exchanger. Secondly, the high temperature generated by the heat exchanger was used to sterilize the indoor unit. A fin-and-tube heat exchanger was utilized in this study, and the amount of condensate water and tube temperature of the evaporator were used as the indicators. The influence of key parameters such as the fan’s rotating speed, compressor frequency, ambient temperature, and operating time on the dedusting and sterilization of the evaporator were analyzed. The experimental results show that the amount of condensate water first increases and then decreases with an increase in fan speed during the dedusting phase, reaching 186 g at a fan speed of 350 r/min when operated under the same condition for 20 min. The condensate water increased with the increase in operating time and the frequency of the compressor. During the sterilization phase, the tube temperature increased with a decrease in the fan speed and reached 58.6 °C at a rotating speed of 200 r/min. Higher outdoor temperatures are beneficial to the tube temperature during the sterilizing stage, but will decrease the amount of condensate water in the dust removal stage.关键词：VRF system;evaporator;self-cleaning;dedusting;sterilization1479|1672|0更新时间：2025-09-03
- 摘要：An air-source heat pump (ASHP) heating system was used to improve the performance of the heating system in an old community of Handan and field test was conducted during the heating season of 2019–2020. In addition, the long-term operating performance was analyzed and the operating characteristics of the system under four different working conditions were compared based on the air temperature and humidity outdoors, temperature and flow rate of the supply and return water, the power consumption, and the practical regulation mode with variable water temperature. The results show that for the energy consumption of the entire heating period, a staged variable water temperature adjustment is beneficial for promoting the energy-saving rate of the air-source heat pump. The high outdoor relative humidity in Handan during winter can easily lead to poor operation of the air source heat pumps and an insufficient heat supply. At this time, the use of a time-varying water temperature adjustment is more beneficial than the staged variable water temperature regulation for improving the system operation. The COP of the second stage of the heating period increased from 1.63 to 1.76 in the third stage, which is an increase of 8%.关键词：air-source heat pump;heating;variable water temperature operation;operating characteristics1547|1810|3更新时间：2025-09-03
- 摘要：This study aimed to optimize the heat production performance of an enhanced vapor injection air source heat pump system with R32. Combined with the structure and actual operation characteristics of a scroll compressor system, a complete mathematical model was established and programmed using MATLAB. After verification of the simulation results with experimental data, the influences of the vapor injection pressure of the system, and the specific volume ratio of the quasi-one-stage compression on the relative vapor injection volume of the system were explored under different ambient temperatures. It was found that the vapor injection heat pump system is more suitable for operation at ambient temperatures of below ?10 °C than an ordinary heat pump system. The optimal operating range of the heating mode of the air-source heat pump system with vapor injection was obtained. Because the specific volume ratio of the quasi-one-stage compression of the system is 1.1, the relative vapor injection volume is the maximum. When the ambient temperature is below -10 °C, within ?10– -5 °C or above -5 °C respectively, the optimal relative injection volume should be within 0.22–0.33, 0.20–0.22 and 0.18–0.20 respectively. The corresponding optimal relative inject pressure ranges 0.85–1.31. Within the range of the optimal vapor injection parameters, the advantages of the enhanced vapor injection air-source heat pump system with R32 are obvious.关键词：vapor injection;air-source heat pump;low ambient temperature;R32;scroll compressor1525|1795|4更新时间：2025-09-03
- 摘要：According to experiments performed on a counter flow dew point evaporative cooling device, the effects of the air inlet temperature, humidity, and air speed on the dew point efficiency, wet bulb efficiency, exergy efficiency ratio, and other performance evaluation indicators were analyzed in this study. The proposed heat transfer amplification coefficient is suitable for dew point evaporative cooling, which can reflect the strength of latent heat exchange in the wet channel and the performance of the device. The research results indicate that when the inlet temperature is 33 ℃ and the relative humidity is 22%, the air speed increases from 1 m/s to 3 m/s, the refrigeration capacity increases from 29.5 kW to 69.0 kW, and the heat transfer amplification coefficient first increases and then decreases, reaching the maximum value at an air speed of 1.8 m/s. In addition, the change law of the wet-bulb efficiency and the dew point efficiency is inconsistent with the temperature drop trend and refrigeration effect. Therefore, both wet-bulb efficiency and dew point efficiency are unsuitable as a performance evaluation index of the device. When the relative humidity is 43% and the air speed is 1.3 m/s, the inlet temperature increases from 25 °C to 40 °C, and the heat transfer amplification factor increases from 11 to 54. The change is consistent with the cooling effect, which can reflect the cooling performance of the device. The exergy efficiency ratio can be used to evaluate the energy saving of this device from the perspective of thermodynamics. Under high temperature and low humidity conditions, the exergy efficiency ratio is larger, and the device is more energy-saving.关键词：dew point evaporative cooling;heat transfer amplification coefficient;dew point efficiency;wet bulb efficiency;exergy efficiency ratio1438|1746|1更新时间：2025-09-03
- 摘要：The cooling capacity of a reciprocating compressor can be finely adjusted using the clearance volume. To study the influence of the clearance volume and the intermediate clearance volume on the performance of the reciprocating compressor, the clearance volume was taken as a single variable to investigate the relationship between parameters such as the cooling capacity and COP and clearance volume under the designated conditions (evaporation temperature of 23.3 ℃ and condensation temperature of 54.4 °C). The result shows that when the clearance volume or the intermediate clearance volume increases, the COP first increases and then decreases, and increasing the intermediate clearance volume is better than the clearance volume for increasing the COP. Among them, when the relative clearance is 0.56%–0.73%, the performance of the reciprocating compressor reaches the maximum value, and the COP can be increased by 0.62%. When the relative intermediate clearance is 18%, the cooling capacity can be reduced by 10%, and the COP increases by 1.31%. In addition, increasing the intermediate clearance volume also helps reduce the exhaust temperature of the compressor.关键词：reciprocating compressor;clearance volume;coefficient of performance;standard conditions1583|1661|0更新时间：2025-09-03
- 摘要：Based on the principle of vapor compression circle, this paper describes the formation and cool storage characteristics of CO2 hydrates in SDS solutions with different filling pressures (3.5, 3.6, 3.7, 3.8, 3.9, and 4.0 MPa) and SDS of different mass concentrations (0.3, 0.5, 0.7, and 0.9 g/L) using a water-cooled direct contact cool storage system. The experimental data were used to calculate the cool storage capacity, cool storage rate, and CO2 hydrate formation mass. The results show that, in comparison with the case of solutions without SDS, the pre-cooling time and cool storage time of the system were shortened in SDS solutions with different mass concentrations, and the hydrate formation mass, total cool storage capacity, and average cool storage rate increased. With the continuous increase in the charging pressure, the cool storage performance of the system was also strengthened. When the filling pressure was 4.0 MPa and the SDS solution mass concentration was 0.5 g/L, the pre-cooling time (5.58 min) and the cool storage time (10.92 min) were the shortest. At this time, the total cool storage capacity (4 021.2 kJ), latent heat cool storage capacity (2 476.8 kJ), CO2 hydrate formation mass (4.95 kg), and average cool storage rate (6.14 kW) of the system reached the maximum value, and the cool storage characteristics of the system attained the best condition. The study has shown that SDS has an obvious effect on the CO2 hydrate cool storage characteristics of this system.关键词：compression refrigeration cycle;cool storage;CO2 hydrate;SDS1479|1702|1更新时间：2025-09-03
- 摘要：In practical applications, pipeline transportation is usually used to transport ice slurry to the area to be cooled for heat exchange. Therefore, it is important to study the flow characteristics of ice slurries. This article is based on an ice slurry preparation and experiment in a flow characteristics test platform. The ice slurry was prepared with a 5% mass fraction urea solution, and the size and distribution of ice particles in the ice slurry were visually observed. The kinematic viscosity of the ice slurry was measured, and the relationships between the pipe diameter, ice packing factor (IPF), flow pressure drop, pipe frictional resistance coefficient, and Reynolds number (Re) were analyzed. The ratio of the experimental value (λ) of the friction resistance coefficient of the ice slurry in horizontal stainless-steel pipes with different pipe diameters to the theoretical value (λ0) was calculated by taking the ice slurry as a Newtonian fluid, and the relationship between the ratio and IPF and Re was analyzed. It was found that λ/λ0 increases with the increase in IPF and decreases with the increase in Re. That is, the ice slurry is closer to a Newtonian fluid under a high Reynolds number, whereas the deviation in ice slurry with high ice packing factor from a Newtonian fluid is larger. A power-law model was used to analyze the flow characteristics of the ice slurry. It was found that the flow characteristic index n' decreased with the increase in IPF. In a pipe with a diameter of 6.0 mm, n' gradually decreases from 1.006 under IPF = 6% to 0.611 under IPF = 26%; however, the consistency coefficient K' is positively correlated with the IPF. In a pipe with a diameter of 8.0 mm, K' increases from 0.015 under IPF = 6% to 0.274 under IPF = 26%. When the IPF is within the range of 5%–30%, n' decreases slightly with the increase in pipe diameter, whereas K' increases gradually with it. To better describe the complex flow characteristics of non-Newtonian fluids, a modified Reynolds number was introduced to quantitatively analyze the slurry. By exploring the relationship between the modified Reynolds number and Fanning friction coefficient, it was found that with the increase in the IPF, the range of transition Reynolds numbers in 4 mm, 6 mm, and 8 mm tubes were 2 500–3200, 1 600–2 300, and 1 500–1 900, respectively.关键词：ice slurry;urea aqueous solution;horizontal straight tube;flow characteristics;ice packing factor1503|1781|0更新时间：2025-09-03
- 摘要：In this study, the contactless weighting method was used to monitor the freeze-drying process of porcine aortas, and the dehydration rate was obtained in real time. For the sublimation drying process, the quasi-steady heat transfer model combined with the change in the dehydration rate could be used to calculate the change law of sublimation temperature, sublimation interface displacement, and heat transfer on each surface. The freeze-drying parameters were set as follows: the pre-freezing temperature was ?40 ℃, the primary drying temperature was ?20 ℃, the secondary drying temperature was 10 ℃, and the pressure of the freeze-drying chamber was 10 Pa. The study showed that the average moisture content of the sample was 74.24%, and the free water content was 71.96%. During the primary drying, the sublimation temperature increased slowly and eventually approached the shelf temperature. As the heat transfer temperature difference decreased, the heat transfer decreased rapidly, and the removal rate of free water decreased gradually. The sublimation of ice crystals was mainly concentrated in the inner and outer walls of the blood vessels, and its heat transfer accounted for 70%–90% of the total sublimation heat. With the decrease in heat transfer, the moving velocity of the sublimation interface decreased gradually. During the early stage of sublimation drying, the mass transfer resistance increased at a constant rate with the thickness of the dried layer, whereas during the later stage, the increasing rate of mass transfer resistance increased significantly with the restriction of the heat transfer.关键词：freeze-drying;heat and mass transfer;dehydration rate;sublimation temperature;mass transfer resistance1566|1732|2更新时间：2025-09-03
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