Design Of Solar Energy-heat Pump Combined Drying Devicee And Experimental Studies On Drying Tilapia

In order to use new energy sources rationally, reduce the energy consumption in the process of drying food, after analyzing the advantage and disadvantage of solar drying, heat pump drying and hot air drying, this study designed and built a solar energy-heat pump combined drying device which could match with the drying performance of kinks of food, tested the relative parameter of independent and combined drying basing on the performance indexes of device, and obtained relevant results. To investigate drying characteristics of device, the matching experiment with drying materials (tilapia) which produced at Zhanjiang city Guangdong province was carried out. This paper also studied the effect of the changes in process parameters on drying characteristic, and made an economic assessment on the solar collector system finally. The following work was finished:1. On the condition of quantitative drying, according to the geographical position and solar radiation of Zhanjiang, this paper designed a solar energy-heat pump combined drying device, analyzed the coupling of it, determined running process of the system, calculated the thermal load of the solar collector, the area of absorber plate,and the size of other assistant equipment. Under the immovable operating condition, this paper calculated the thermal load of heat pump drier, determined configuration of device and relevant size, and analyzed the functions of the device. This device is a solar energy- heat pump combined drier with multi-function, which could operate independently or jointly at variable condition. According to the change of weather, operator could choice solar drying, heat pump drying, or the combined drying with drying medium cycled by open, Semi-open, or closed type, and operator also could change the operation mode to adjust the different conditions for the characteristics of drying materials during the process.2. After building a solar energy-heat pump combined drying device, we tested and analyzed the performance of it, results showed that: The SEMR of heat pump decreases with the increase of condensing temperature, and increases with the increase of evaporating temperature. The heating efficiency of heat pump system is 2.5,while that of the combined drying system is 5.0,6.7,8.0 respectively when air temperature at inlet of heat pump evaporator was 40℃, 45℃, 50℃,Which is higher than heat pump drying system obviously. The device could regulate and control temperature well, and satisfy the requirement of operating conditions.3. The paper made the drying experiment of Tilapia while heat pump and solar drying system operated alone, compared and analyzed drying curves and drying rate curves of them. The drying time and power consumption is closely related with the drying conditions, and the higher the drying temperature is, the faster the drying rate is. The lighter the material is, the lower water content can be obtained at the same drying time. All of those provide a theoretical basis for production process and the research of solar energy-heat pump combined drying device.4. A technological and economic assessment on the solar collector system was also made and presented in this study. Result of the analysis showed that the repayment period of the device was 2.3 years, and thus solar collector is economically feasible matter...