Parameter optimization of multistage closed series heat pump drying system

Abstract

In the heat pump drying system (HPDS), there are few studies on energy efficiency and system process optimization, so based on the basic principle of heat pump drying, this paper proposes a multistage closed series drying system for corn drying to strengthen the research gap. The drying system is simulated and researched by establishing mathematical model and programming with MATLAB software. The calculation results show that the coefficient of performance (COP) of the four stage closed heat pump drying system (HPDS) can reach about 5.5 in summer and 4.5 in winter; with the increase of the cooling temperature difference of the auxiliary evaporator, the COP values of system 1, 3 and 4 increase about 10% in summer, while the COP of system 2 is almost unchanged, and the COP changes of the four systems in winter are very small; the compressor powers increase except that of system 1. With the increase of the return air temperature, except that the COP of system 2 does not change much, the COP of the remaining systems decrease about 15% in summer and 5% in winter; the compressor power increases about 40 kW except for system 2 in summer and decreases largely in winter for each system. And the payback period of the system is about 1.22 years.