Eventos Anais de eventos
ENCIT 2018
Brazilian Congress of Thermal Sciences and Engineering
OPTIMAL HIGH PRESSURE CORRELATION FOR R744 DIRECT EXPANSION SOLAR ASSISTED HEAT PUMP FOR DOMESTIC HOT WATER
Submission Author:
Willian Moreira Duarte , MG , Brazil
Co-Authors:
Willian Moreira Duarte, Tiago de Freitas Paulino, Sabrina Nogueira Rabelo, Luiz Machado, Antônio Maia
Presenter: Willian Moreira Duarte
doi://10.26678/ABCM.ENCIT2018.CIT18-0235
Abstract
Heat pumps can operate with a variety of refrigerant fluids. Among of them, the CO2 has excelled because of its favorable thermodynamics characteristics and zero net impact in climate change. The control of the gas cooler pressure is of utmost importance as it plays an important role in the system coefficient of performance (COP). In some research works it was proposed correlations to estimate the optimum high pressure, but none of them focusing solar assisted heat pumps. In this work it is presented a mathematical model of a Direct-Expansion Solar Assisted Heat Pump (DX-SAHP). This model was employed to investigate the influence of the high pressure on the system thermal performance. The results obtained from simulation were compared with the values estimated using correlations available in the literature. The mean difference of the optimum pressure found comparing both approaches was -25%. A new correlation was proposed in function of water flow rate and solar radiation rate. The mean difference of the optimum pressure obtained through simulations and by using the proposed correlation was 2.6%.
Keywords
R744, Transcritical cycle, Optimum pressure, COP, Solar assisted heat pump
