Desenvolvimento de uma bomba de calor para secagem de sementes.

Abstract

A heat pump was built for the production of cold air with low relative humidity, with the objective of drying thermally sensitive products with seeds. The process consists of the utilization of compressed vapor cooling system, employing R22 as the refrigeration gas, where the surrounding air condenses part of its water vapor that exists in the air, when it passes through the cooling system’s evaporator, and then heats this air when it passes through the condenser. By controlling the massic flow of the refrigerating fluid and the air flow it was possible to obtain temperatures and relative humidities of 25 ºC and UR 55%; 25 ºC and UR 35%; 30 ºC and UR 40% and 35 ºC and UR 35%. Simulations were made of the drying of bean seeds for these air conditions obtained. For the simulation we used the computer program developed by Cavalcanti Mata (1996) for beans. The simulated results show that the conditions of the air produced by the heat pump allow the drying of bean seeds from 35% to 13.5% humidity, dry base, in an average period of time of 45, 21, 20 and 15 hours respectively.