Análise da interação compressor-tubo capilar na adaptação de um sistema de refrigeração de R134a para R290 ou R600

Abstract

In a context with environmental concern getting more and more importance, products that are aggressive to the environment are receiving less and less demand. For instance, the refrigeration industry is being directed to abandon some not ecological refrigerant fluids (CFCs e HFCs).Just as the R134a has replaced the R22, today the goal is to replace the R134a by more ecological fluids as R600a and R290. In that way, this monograph has as principal objective to analyze the transition of a refrigeration system, which works originally with R134a, to R600a and R290. For that, it was realized a theoretical comparison study, looking for analyzing the impacts that this change causes to the mass flow. It was used a numerical modelings which involved volumetric efficiency for the compressor and the capillary tube length’s calculus. The goal is to achieve the mass flow balance on the system. It was observed that the superheat influence to the capillary tube length is not expressive in comparison to the evaporation temperature. In all the cases, R600a needed a bigger length to the same difference of pressures in comparison to R134a and R290. Besides that, at evaporation temperature equal to -15ºC, an interchangeability is observed between R134a and R290. In that case, it is possible to switch the gas of the circuit with no changes at the capillary tube length. For the R600a, that is not possible at all the studied conditions.