Energy and Exergetic Evaluation of Thermodynamic Systems Applied to Water Heating at Low Temperatures

Abstract

Given the changes in human needs in the 21st century, which are increasingly dependent on different energy sources, this work aims to compare the energetic and exergetic efficiency of a shower heated by electric resistance and a solar heater. The method employed is based on the first and second principles of thermodynamics. We found that, under conditions at low heating temperature, the shower has better exergetic efficiency due to solar heating when compared to electrical energy since the destroyed exergy is lesser in the solar heater. Energy efficiency (quantitative aspect) is bigger in electrical resistance because presents better performing energy than solar energy. Therefore, for the final use, of heating at low temperatures, the solar heater is recommended from the thermodynamic perspective.