STUDYING CARBON DIOXIDE AND ACETONE MIXTURES IN A SINGLE-STAGE ABSORPTION-COMPRESSION CYCLE FOR HEATING AND COOLING APPLICATIONS

Abstract

This communication analyzes the performance of a zeotropic fluid, composed by the mixture of carbon dioxide and acetone, in a vapor compression cycle with a solution circuit. The working fluid is characterized by a high temperature glide that depends on the mixture composition. The high critical temperature of the acetone and the good thermal properties of carbon dioxide makes this mixture a promising heat transfer fluid for industrial heat pumps that need to supply energy for heating and cooling processes. The heat pump analyzed has these components: evaporator, compressor, condenser, two internal heat exchangers and an expansion valve. In addition, a second liquid line with a solution pump is used to circulate the liquid from the gas-liquid separator to an internal heat exchanger, and then, to the condenser. In this way, the gas-liquid separator allows the fluid to leave the evaporator as a vapor-liquid mixture. This heat pump configuration working with the CO2/acetone mixture could provide the energy needs of an industry that requires both heating and cooling. Depending on the binary mixture composition, the source and sink temperatures change as well as the coefficient of performance. For instance, an 55% CO2/45% acetone in mass fraction, can provide heat to the sink at an average thermodynamic temperature of 110ºC, and refrigeration at an average thermodynamic temperature of 0ºC, showing a total COP of 2.55. This configuration would work at a high pressure of 40 bar and a low pressure of 10 bar.