Study On Solar Adsorption Precooling Storage Techniques For Fruits And Vegetables

With the development of economy, environmental protection and energy crisis have become the focus of world attention. Therefore, the development and utilization of renewable energy has very important practical significance. Our country is agricultural production, consumption, waste of country, especially the waste is very serious in the refrigeration and fresh of fruits and vegetables. Precooling is an important link of fruit and vegetable cold chain, the first time precooling of fruits and vegetables can maximum guarantee its quality. At present our country most fruits and vegetables after harvest are directly transportation and sales without precooling, so the quality of fruits and vegetables is badly affected. The traditional fruit and vegetable precooling storage need electric consumption, It makes its application used in the fields to be limited some extent. If the solar energy is used as energy for the fruit and vegetable precooling storage, not only it can improve the quality of the storage fruit and vegetable, but also can use the perfect combination of green energy.This paper is comprehensive domestic and foreign research status of solar adsorption refrigeration technology, used activated carbon-methanol as the working medium, and respectively using vacuum tube-water cooling heat adsorption bed, flat-natural cooling heat adsorption bed two sets thermal adsorption bed are studied, and the mode of batch and continuous refrigeration cycle has carried on the numerical computation and related experiments.According to the calculation of cooling load structures the test bench and designs the vacuum tube collector adsorption bed, plate collector adsorption bed, condenser, evaporator and throttling set. Meanwhile put forward the improvement for the mass transfer channel of adsorption bed, the cooling water pipe, the system sealing.Through numerical calculation and analysis of the collector adsorption bed, it is concluded that the adsorption bed temperature, adsorbent adsorption rate with time. When the sun largest radiation intensity is790W/m2and its strength according to the sine changing, calculate the flat adsorption refrigeration system refrigeration coefficient COPref is0.594, the vacuum system of COPref is0.517, at the end of the stripping plate in the system residual methanol percentage is6.3%of all methanol, vacuum tube is3.8%.Three groups of experiments are carried out using the experiment device:the first is natural-cooling tablet system intermittent refrigeration, and the second is the water-cooling vacuum system intermittent refrigeration, the third is the vacuum tube water continuous refrigeration system. Experiment is measured in the evaporation temperature0℃and the condensing temperature40℃, under the condition the intermittent flat solar refrigeration system refrigeration coefficient COP is0.109～0.118;The intermittent vacuum tube solar refrigeration system refrigeration coefficient COP is0.095～0.102;The continuous vacuum tube solar refrigeration system refrigeration coefficient COP is0.105～0.110.The adsorption bed temperature of the experimental results and numerical results are compared, and the accuracy of the established model is verified.This paper analyzes the solar adsorption cold storage technology performance, objectively points out the existing problems, and puts forward suggestions for future work.