Diseño y construcción de una bomba de calor con R600a para el secado de 25 kg/día de arroz con cáscara mediante convección forzada

Abstract

This project is based on the design and construction of a heat pump for drying paddy rice, the thermodynamic process of the equipment is based on a real cycle of steam compression cooling, the working fluid is R600a, which It is shown as an ecological alternative to traditional refrigerants with high potential for destruction of the ozone layer (ODP) and global warming (GWP), the main cooling equipment used for the construction of the heat pump are: two compressors 1/4 of hp which are placed in parallel to increase the flow and pressure of the system, a 7/8 hp condenser, a 3/8 hp evaporator and an expansion valve. The results achieved through numerous tests allow to verify the temperature of entry and exit of each of the refrigeration equipment, with a special focus on the condenser as it will be considered for the study as a cross flow heat exchanger, the exchanger is considered of this type because two axial fans are used to extract the hot air from the condenser and by forced convection send that air to the drying pot, the maximum temperature reached by the condenser in the different tests was 72 ° C, reaching the pot drying between 42 and 44 ° C, sufficient temperature to achieve drying of the product in approximately 4 hours for a load of 5 kg. The equipment was launched and tested in the city of Guayaquil with an average ambient temperature of 30 ° C, the drying time varies depending on the relative humidity of the rice, the ambient temperature and the load, increasing the drying time to greater product load and relative humidity. Although the implementation of a heat pump in the rice drying industry represents a high investment compared to traditional and other drying techniques using fossil fuels, its great advantage lies in the costs compared to the use of liquefied petroleum gas (LPG) and diesel, not to mention the decrease in CO2 emissions and the development of renewable energy.