Static Drying Experiment Study Of Solar-assistant Heat Pump In Entire Warehouse Grain Drying

China is the largest food producer and consumer in the world, the food quality, quantity and safety are directly related to the development of the national economics and social stability. The main reasons for food losses in the dry storage process are that the temperature and moisture content not well controlled. The conventional drying method are not only large energy consumption, but also will cause environmental pollution. Solar energy is clean and renewable energy, heat pump is the only heat recovery system which enables the temperature of waste heat to be raised to more useful level, and heat pumps have significant energy saving potential. This paper based on reducing energy consumption and improving drying effect, proposed a new type of drying technology-solar assisted heat pump drying grain system.Based on the similarity theory, this work build a solar-assisted heat pump warehouse grain static drying system, in the grain drying process, the heating equipments, solar and heat pump performance effects were tested by experimental methods, and the changes of grain moisture and temperature were detected, the entire granary drying effect was evaluated.In this paper, three experimental conditions were carried out. Results show that thermal efficiency of solar air collector can reach60%under designed condition, and the COP of heat pump can reach2.7under experimental condition, and the maximum heating capacity can reach3000W. solar and heat pump are efficient running and running well. Under experimental condition1. the grain drying effective time is96h. the initial moisture content is13.4%. the end moisture content is11.4%. Under experimental condition2. the grain drying effective time96h. the initial moisture content is l9.6%,the end moisture content is14.2%.Experimental results show that under the same drying effectiveC time,the higher the initial moisture of the grain,the faste the precipitation speed, and the greater precipitation magnitude. Under cxperimental condition3,the grain drying effective time is10h,the preciptation magnitude is1.7%,experimental results show that the drying time is significantly shortende,but the preeopitation speed is still fast,and the precipitation magnitude is still large.The results of this study also shows that solar-assistant heat pump drrying system can be based on actual weather conditions for the optimal match、thus achieving minimum energy consumption of the drying system.This drying technique is a good use of solar and heat pump heating and dryinng advantages and it has a good application prospect.