Evaluación experimental del comportamiento del refrigerante R134a utilizado como fluido de trabajo en un colector/evaporador de placa plana de 0.08 m2.

Abstract

This project presents the results of the experimental evaluation of the behavior of refrigerant R134a and R600a, used as working fluids in a collector/evaporator of flat copper plate, of a direct expansion heat pump, assisted by solar energy. The collector/evaporator and condenser components were designed as part of a prototype, whose objective was to reduce the effective occupation area of the collector/evaporator, according to the specifications of the compressor. With the methodology used, a series configuration was proposed and an optimum area of 0.08 m2 was obtained. On the other hand, the heat pump consists of a variable speed compressor from 1200 to 3000 rpm, as well as an expansion valve electronic, which allows to control the passage of refrigerant to the system. An automated monitoring system of 20 thermocouples was installed on the surface of the collector/evaporator, obtaining real-time data on the behavior of the collector pipe with solar radiation. The COP of the pump was established by measuring the temperature rise in 5 kg of drinking water, due to the heat transfer from the condenser. The environmental conditions were measured with the help of a calibrated weather station that validates the results and the data processing was carried out in the SITRAD program. From this, information and results of the properties of the refrigerant both R134a and R600a were obtained. As well as the influence of environmental conditions on the system. The first tests were performed with refrigerant R134a, but due to the high global warming potential (GWP) of 1300, a transition was made to R600a refrigerant, since the latter has a global warming potential (GWP) of 3. The main results of this investigation were, the maximum water temperature reached with R 134a was 40.2 ° C in a span of 45 minutes and for refrigerant R600a it was 55 ° C in a lapse of 75 minutes. On the other hand, it was established that in addition to the incidence of solar radiation, the main variable that affects the operation of the heat pump is wind speed and the position of the evaporator collector. Finally, a comparative study of the properties of the two refrigerants was proposed and a fully installed equipment is left for future research.