A novel thermoeconomic analysis under dynamic operating conditions for space heating and cooling systems

Abstract

Thermoeconomic analysis allows for a deep understanding of the cost formation process within an energy system, providing insights into the possible routes for improvement. Several thermoeconomic approaches are well-established for application in systems with steady operating conditions, such as power plants, while a limited number of applications to air-conditioning systems in buildings have been proposed, due to the difficulties in dealing with very irregular load profiles and unsteady plant operating conditions. This study investigates the potential of Thermoeconomics as a support for decision making in building energy systems, proving its capability to identify trade-offs between cost fractions related to capital investment and efficiency. The proposed approach to thermoeconomic analysis of dynamic systems introduces some methodological novelties, such as the use of a preliminary dynamic simulation to calculate “averaged energy flows” on an arbitrary time basis and the adoption of a flexible super-structure, capable to reflect the different operating conditions throughout the year. That is then applied to a school dwelling, supplied with space heating and cooling and a mechanical ventilation Air Handling Unit. The sources of irreversibility are evaluated and the main targets for improvement are identified, calculating the trends of exergetic, exergoeconomic and exergoenvironmental costs on a monthly basis.