It is very meaningful to predict the temperature and thawing time during the thawing process of frozen food in production and life, this paper proposes a physical model of cylindrical frozen food during the thawing process, combine the finite difference method with element balance method to solve the thawing time and the temperature at regional center R/2 and boundary nodes. Take the beef as an example for the experimental verification. Through numerical calculation and experimental verification, the maximum error between the theory thawing time and experiment is 8.4%. The results show that: it is highly consistent with the experimental results that using numerical method to predict the thawing time and temperature change curve, at the same time, the temperature maximum error in center area is 1.2°C, the temperature maximum error of R/2 is 0.8°C, the temperature maximum error of the boundary node is 1.5°C, so the numerical simulation in studying thawing of freezing food is fairly reliable.

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This paper discusses the importance of per-cooling vegetable and fruit, establishes a mathematical model of the solar adsorption refrigeration system collector bed. It applies activated carbon - methanol as working pairs, takes solar vacuum tube－water cooled collector bed for refrigerating, adsorption temperature and adsorption rate versus time are calculated , draw the corresponding curve figure. Analyses solar adsorption refrigeration system performance and puts forward the improvement direction.

Mathematical model on heat and mass transfer of hemisphere-shaped in the thawing process was established, with finite-difference numerical method, which was used to analysis the thawing time of hemisphere-shaped food and it's core temperature history. The results show that numerical methods can be used to discrete time and space in any step, predict temperatures on any node in every time interval, and also predict thawing time of food. The result of the experiment show that the simulation results match well with the experimental results. The maximum deviation is 6.7%.

This paper discusses the principles of solar adsorption refrigeration and the characteristics of air conditioning radiation, designs solar adsorbent bed with activated carbon - methanol as working pair and its accompanying condenser, evaporator, radiant cooling tubes and other equipment. Through experiments, it changes water supply by change flow rate of chilled water, in order to get chilled water supply and return water temperature and room temperature curve. To analysis COP value of system under different flow rate of chilled water, and get the optimal flow rate of chilled water supply.