Method for evaluating the dynamic thermal performance of heating terminals based on an analysis of heat quantity and grade

Behavior energy conservation in buildings greatly impacts energy conservation and carbon reductions at the national level, and part-time space heating has become an important part of building operation. Under these conditions, heating terminals with different properties differ significantly in their heat consumption and heat grade demands. However, a comprehensive evaluation of the transference of quantities and grades of heat during the part-time heating of different terminals remains lacking. In this study, we developed a entransy-based analytical method and used it to compare the experimental and field-measured performances of three typical heating terminals (a radiator, radiant flooring, and a fan coil) from start-up to stabilization. The entire energy flow networks - from the heat source to the outdoor environment - were analyzed. Transient and cumulative entransy dissipation was analyzed to determine the energy utilization trends of the terminals. The dissipations between thermal nodes were also explored to intuitively reflect the key process(es) limiting heat transfer in a terminal. Further, we compared variations in heating performance under different operating durations to determine the applicability of each terminal type. Our results suggest that the radiant floor had the greatest entransy dissipation during start-up owing to its high thermal storage capacity and transfer resistance. However, because of the high thermal resistance of the terminal-to-chamber process, the entransy dissipation of the radiator was the greatest following stabilization (accounting for 57.0%), and the difference in the dissipation between radiators and the other terminal would increase with longer operating times. CO 2021 Elsevier B.V. All rights reserved.