Research on operation strategy and performance prediction of flat plate solar collector with dual-function for drying agricultural products

In this study, a flat plate solar collector with dual-function (FSDF) embeddable in a hybrid solar drying system is proposed and constructed. In the present drying system, air outlet temperature of FSDF is controlled within the suitable drying temperature range. Thereby the efficiency of solar energy utilization and the quality of dry product can be improved. This study has revealed, for the first time, solar drying air temperature can be controlled by adopting operation strategy based on FSDF. The operation strategy, thermal performance and economic analysis of flat plate solar collector with dual-function hybrid dryer (FSDFHD) are investigated. A detail mathematical modelling is developed to calculate the thermal parameters of FSDF. Performance test of FSDF were also carried out in the September of 2017. The results show that there is a good agreement between the simulated and experimental values of these parameters. For the glass cover, absorber plate and outlet air temperature, the root mean square deviation (RMSD) value is 8.9%, 11.9% and 10.5% respectively. The range of maximum heat collecting efficiency of FSDF is 32.5%-50.8% for three different heat collecting modes. The range of heat loss coefficient of FSDF is about 2.5-6.2 W/(K m2). In addition, operation strategy of FSDFHD all year round is given and analyzed through case study. The solar fraction and energy distribution of FSDFHD can be calculated at any day of the year. Finally, economic analysis is conducted to study the application of FSDFHD in china. The results show that FSDFHD has applicative enough for their advantages in economy with the help of judgement criteria of the present value of the cost and the annual cost. Thus, this study can provide theoretical basis for designing and operating strategy of FSDFHD in drying agricultural products.