Power Flow Method-Based Integrated Modeling and Optimization for Building Heat Transport and Gas Refrigeration System

Abstract

The combination of heat transport and heat-work conversion processes in thermal systems highlights the importance of the integrated modeling and optimization method. Following the analogy between power flow and heat transfer, this study introduces a power flow model for a building heat transport and gas refrigeration system that combines the linear temperature difference-based thermal resistances, energy sources, and additive thermo-motive forces. Holistic system constraints are deduced from the power flow model and constructed by combining Kirchhoff’s law with the heat-work conversion equations. The constraints represent each component’s performance and the system topological characteristics and reveal the system-level overall thermal energy transport and conversion discipline. For validation, an optimization case that minimizes the net input work of this system is introduced. The results show that the same heat capacity rates are necessary for the ambient and indoor air for the minimum net input work. Meanwhile, improvements in building thermal insulation performance and incremental increases in the total thermal conductance of the heat exchangers and total heat capacity rates of the working fluid all reduce the net input work. That is, the power flow method is a feasible and useful tool for the integrated modeling and optimization of thermal systems such as thermal management in the building or aircraft fields.