| dc.description.abstract | Mathematical models are increasingly explored by the scientific community in studies of thermal equipment to assess the feasibility of replacing traditional refrigerant fluids with ecological refrigerants based on 4E analysis (energetic, exergetic, environmental and economic). This doctoral work aims to develop and validate a mathematical model based on the analysis of the 4E and to carry out an experimental study of a Direct-Expansion Solar-Assisted Heat Pump (DX-SAHP) for residential water heating operating with a fluid selected from ten candidates (R152a, R744, R1234yf, R1234ze(E), R1233zd(E), R170, R290, R600, R1270 and R600a). The environmental analysis is based on the total equivalent warming impact (TEWI) and the economic analysis is based on the payback. In addition, the mathematical model of the system was validated using the infrared thermography technique. The experimental study was developed in the city of Belo Horizonte through a prototype designed and built in order to carry out the 4E analyzes of the indoor and outdoor operating system for different final water heating temperatures. After validating the developed model, the influence of environmental and geometric parameters on the system performance is investigated through simulations. The experimental study revealed that the energy performance and exergy efficiency of the system when operating in the outdoor condition were, on average, 29.8 and 17.4%, respectively, higher compared to the indoor condition. In addition, operating the system in the indoor condition was, on average, responsible for 10.7% more CO2 emissions and also resulted in a payback time for the system, on average, 9.30% higher when compared to the condition billboard. It is identified, through model simulations, that solar irradiance is the environmental parameter that most contributes to the increase in energy performance (69.3% on average) and exergy efficiency (8.72% on average). In addition, the increase in ambient temperature contributes the most to the reduction of greenhouse gas emissions (88.6% on average), but promotes the longest payback time for the system. | |
