《制冷学报》摘要 09年第五期

LIN Peng, WANG R Z, MA Q

(Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, Shanghai200240, China) Abstract The research on long distance transportation technology of low-grade heat is reviewed. It consists of reversible chemical reactions, phase change materials of thermal storage and transportation, hydrogen-adsorbing alloys, solid-gas adsorption, and liquid-gas absorption. Their basic principles and research development are discussed, and the advantages and shortcomings are compared. The conclusion can be drawn that the liquid-gas absorption cycle may be prospective in application. 25Refs. In Chinese. Keywords Pyrology; Energy transportation; Absorption refrigeration; Absorption heat pump; Waste heat utilization E-mail：linpeng0478@sjtu.edu.cn

ZHAO Li-ying, NAN X H, YANG Y B

(Xi’an University of Architecture and Technology, Xi’an710055,China) Abstract The temperature distributions in an office in Xi’an with radiator heating and VRV air conditioning modes were measured by IMP, respectively. The results show that the value of temperature gradient in the working area was about 3℃ with the VRV air conditioning mode and 0.7℃ with the radiator heating mode. A mathematical model was established for the real office, and the indoor temperature field and the velocity field with these two heating modes were simulated. The numerical simulation results are in agreement with the data measured. The features of these heating modes and their influence on the indoor thermal environment were analyzed. Our results indicate that the temperature field and the velocity field in the room with the radiator heating mode may be more uniform than those with the VRV air conditioning mode. 8Refs. In Chinese. Keywords Municipal engineering; VRV air conditioning heating; Radiator heating; Temperature field E-mail：zhaoliying1983@163.com

(WU Jing-yi, JIANG M L, WANG R Z et al)

Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, Shanghai200240, China Abstract Air source heat pump water heaters(ASHPWH) run in heating mode all year around. The EER of the units varies with the difference of local meteorological conditions and hot water demand of users, and thus the EER only under the nominal working conditions is difficult to accurately reflect the actual energy saving effect of the units. In this paper, a new evaluation criteria of ASHPWH energy efficiency on the basis of the annual integrated operating conditions is proposed, in which the weather conditions of different regions and actual application of users in the south of China are considered. The results show that the present energy efficiency assessment method of heat pump water heaters based on the annual integrated operating conditions is more reasonable. 6Refs. In Chinese. Keywords Pyrology; Air source heat pump water heaters; Annual comprehensive working conditions; Energy efficiency ratio; Hot water demand E-mail：jywu@mail.sjtu.edu.cn

SHANG Ping-jun1, YUAN X L2

(1.Wuxi Institute of Technology, Wuxi214121, China; 2.Xi`an Jiaotong University, Xi`an710049, China) Abstract The experiment was conducted on the effects of ambient temperature and humidity on defrosting characteristics of an air source heat pump. The variation characteristics of fin surface temperature, subcooling temperature, and superheating temperature during the defrosting cycles and heating cycles were obtained with the acquired real-time test data. The effects of ambient temperature and humidity on recovery time of heating capacity, decline time of heating capacity, and stable heating time were analyzed. The results show that the sudden changes of the variation rate of the evaporator outlet temperature and the periodic fluctuation of the temperature occurred at the different ambient temperature and humidity, and heat capacity began to decline and frost began to grow up rapidly at this time. In addition, the sudden change of the variation rate of the evaporator outlet temperature rose by 200% and decline time of heating capacity decreased by 70% when air relative humidity increased from 70% to 90%.5Refs. In Chinese. Keywords Pyrology; Ambient temperature and Humidity; Defrost control E-mail：shangpingjun@163.com

SUN Zhi-gao1,2, JIANG C M2, SUN L1

(1.School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou215011, China; 2.School of engineering, Sun Yat-Sen University, Guangzhou510275, China) Abstract Experiment on phase change conditions and phase change latent heat of tetra-n-butyl ammonium bromide aqueous solutions for cold storage. Tetra-n-butyl ammonium bromide (TBAB) aqueous solution can form semi-clathrate hydrate at suitable solution concentration and temperature of chilled water at atmosphere pressure. It is a potential solid-liquid phase change material for cold storage in air conditioning systems. The solid-liquid phase change conditions of TBAB aqueous solutions were experimentally measured using the test rig for hydrate formation. The experimental results show that the phase change temperature of the TBAB hydrate increased with the increase of the concentration of the TBAB aqueous solution when the solution concentration was less than 45%, but the increment of the phase change temperature decreased when the TBAB solution mass fraction exceeded 25%. The phase change temperature of the TBAB hydrate decreased with the increase in the concentration of the TBAB aqueous solution when the solution concentration was more than 45%. The phase change latent of the TBAB aqueous solution was measured using the DSC rig and the test result shows that the phase change latent was about 195.9 kJ/kg.10Refs. In Chinese. Keywords Engineering thermophysics; Cold storage; Phase change conditions; Phase change latent heat; Tetra-n-butyl ammonium bromide E-mail：szg.yzu@163.com

CHEN Shu-hua1,2, ZHAO Q C1, 2, LIU X W1 et al

(1. R&D Institute of Fluid and Powder Engineering, Dalian University of Technology, Dalian116012, China; 2. School of Environment and chemical Engineering, Dalian University, Dalian116622, China) Abstract The influence of freezing-thawing process with the combination of high pressure and low temperature and with the conventional freezing-thawing method at ambient pressure on the quality of potato samples was experimentally investigated, respectively. The results show that the quality of the potato processed with high pressure and low-temperature was higher than that with the conventional process at ambient pressure, including better texture, lower dehydration rate and less broken microstructure, in particular, at PSF 200MPa and -20℃. When the pressure was higher than 100MPa, the clear inactivation on bacteria was noticed, and phase change facilitated the inactivation. 9Refs. In Chinese. Keywords Horticulture; Potato; High pressure; Low temperature; Freezing; Thawing E-mail：flower-chen@163.com

LI Jin-tian1 , MAO J F1, LI W H1 et al

(1.Engineering Institute of Corps of Engineers, PLA Univ. of Sci. & Tech., Nanjing210007, China; 2. Architectural and Civil Engineering Institute, Ezhou University, Ezhou436000, China) Abstract The supercooling mechanism of salt hydrates was analyzed to solve the supercooling of thermal storage material, sodium acetate trihydrate. The comparison experiment on three groups of different formulae was conducted under the same experimental conditions. Solidification process was analyzed based on the experimental photos of solidification and temperature curves of step cooling recorded. The results show that 5% (in mass) nucleating agent, twelve-hydrated disodium hydrogen phosphate, could reduce the supercooling degree of acetate hydroxide trihydrate to some extent but the supercooling degree was still large. However, the supercooling degree of sodium acetate trihydrate could decrease clearly by adding 3% (in mass) thickener gelatin and 5% (in mass) twelve-hydrated disodium hydrogen phosphate. 7Refs. In Chinese. Keywords Engineering thermophysics; Sodium acetate trihydrate; Supercooling; Phase change; Temperature curve for step cooling E-mail：navyeast@gmail.com

ZHANG Zhen, XIE J

(College of Food Science & Technology, Shanghai Ocean University, Shanghai201306, China) Abstract The numerical simulation of flow and temperature fields in the static pressure tank and the freezing area was performed with CFD technology based on the characteristics of airflow distribution in impingement freezers. Foodstuff and mesh belts were regarded as the inner heat source and the porous media, respectively. The results show that, in the static pressure tank, the air velocity decreased and the pressure distribution was uniform gradually in the corner between the plates and clapboards with the increase in the aperture of the perforated plates. Moreover, there was Coanda effect around the freezing food in the freezing area and the food temperature decreased from the inlet to the outlet of the freezing area. It is likely that the optimum rate of the opening aperture was 5%, which could ensure the center temperature of food below –18℃ at the end of freezing. 11Refs. In Chinese. Keywords Pyrology; Quick freezer; Perforated plates; Impingement E-mail：jxie@shou.edu.cn

ZHOU Hui-juan1,2, QIAO Y J1,2 ,WANG H H1 et al

(1.Agro-product Fresh Keeping and Processing Research Center, Shanghai Academy of Agricultural Sciences, Shanghai201106, China; 2.College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China) Abstract `Datuanmilu` is a kind of soft-pulp peach with abundant nutrition and sweet flavor but its storage and fresh-keeping is still difficult because of its particular biological and physical characteristics. In our study, changes in weightlessness rate, firmness, respiration rate, ascorbic acid, total soluble solids, total sugar content , titratable acidity and MDA content of `Datuanmilu` peaches were measured during storage at 0℃, 2℃ and 4℃, respectively. The results show that the drop of the contents of total soluble solids, titratable acidity, and Vc could be restrained during storage at 0℃ or 2℃. Moreover, the firmness and sarcocarp tint could be maintained, and the peak of peach respiration could be delayed. In addition, the changes of the total sugar content and the weightlessness rate were slight. It appears that 2℃ may be the optimum storage temperature for `Datuanmilu` peaches.15Refs. In Chinese. Keywords Horticulture; Datuanmilu; Storing at low temperature; Biological and physical characteristics; Effects of fresh-keeping E-mail：yjqiao2002@sohu.com

WANG Feng-hao1, LIU X D1, LI Y B1 et al

(1.Building Energy Research Center, Xi’an Jiaotong University,710049; 2.Building Energy & Environmental Technology Research Unit, Division of Building Science and Technology, City University of Hong Kong) Abstract The airflow characteristics in a typical office building with stratum ventilation and displacement ventilation were investigated, respectively, in the conditions of six air changes and 19℃ supply air temperature. The temperature fields, velocity fields and concentration fields in the working area and the surrounding region of human body were analyzed and compared. The airflow characteristics and thermal comfort with these two ventilation systems were studied by the numerical simulation. The experiment and calculation results show that, with the stratum ventilation, the IAQ and the thermal comfort in the breathing zone will be favourable, and the heat and air pollutants in the breathing zone can be removed effectively. 12Refs. In Chinese. Keywords Municipal engineering; Stratum ventilation; Displacement ventilation; Airflow characteristics; Thermal comfort E-mail：fhwang@mail.xjtu.edu.cn