Exergy, exergoeconomic and exergoenvironmental assessments of experimental hybrid energy systems for hot water production to improve energy sustainability

Abstract

Hybrid energy systems have proven their efficacy in improving energy sustainability. This paper focuses on the design and evaluation of various hybrid energy systems for hot water production in the experimental plant of the Laboratory for Quality Control in Buildings. The experimental facility was created to test and control various systems for energy supplies in buildings. In this work, three thermal installations were investigated: (1) a combined boiler cogeneration system, (2) a combined boiler solar collector system, and (3) a combined boiler heat pump system. After configuring each system in the laboratory, defining the control, and running the experimental essay, the corresponding data were obtained and treated. The exergy concept matches very well with the goal of promoting new systems that efficiently integrate renewable and nonrenewable energy resources. The exergy analysis and its extended assessments, the exergoeconomic and the exergoenvironmental, were applied to the designed systems. The results show that DHW production by the combined boiler solar thermal collector system is the most expensive in terms of the exergy cost index (about 33.29 kWhex/kWhex). DHW production by the combined boiler cogeneration system offers the lowest exergy unit cost (about 21.15 kWhex/kWhex). Based on economic and environmental indexes, DHW production by the combined boiler solar thermal collector system is the most suitable option. Its unit exergoeconomic cost is around 2.15 €/kWhex, and its exergoenvironmental unit impact is equal to 9.35 kg CO2/kWhex.