MATHEMATICAL MODEL OF HEAT ENERGY REGIMES OF HEAT PUMP DRYING PLANT

Abstract

In the post-harvest processing of grain and seeds, the drying process is the most energy-intensive. During the drying of seed, energy consumption increases by 1.3–1.4 times compared to the drying of grain. Significant energy costs for the process of dehydration of grain are a prerequisite for the introduction of new energy-saving equipment and increase the efficiency of existing plants through their technical and technological modernization. Reduction of energy consumption in the agro-industrial complex for drying grain is possible through measures aimed at reducing heat emissions from spent fuel, the use of renewable energy sources and secondary energy resources. These measures are implemented, including the use of energy-efficient heat pump equipment. To determine energy and technological efficiency, rational modes of operation of heat pump drying equipment and its design parameters, it is necessary to have a method of calculations based on mathematical models of thermal energy processes in the equipment of such units, which usually operate in non-stationary conditions. The research was based on the use of the main provisions of the theory of heat and mass transfer. In the article, based on the theoretical analysis of heat and mass transfer processes in a heat pump dryer, a mathematical model of nonstationary heat and mass transfer processes is developed. The synthesized mathematical model can be used in the development of automatic control of the drying process of agricultural products, and the transformation of the dynamic model into static by excluding derivative variables that characterize the process will determine the rational operation of the heat pump system of the grain dryer. The use of heat pumps for the preparation of drying agent or cooling air in low-capacity grain dryers will eliminate the use of natural gas, diesel and furnace fuel.