Optimization of Capacity Configuration Design for a Composite System Combining Medium-Deep Ground Source Heat Pump with Auxiliary Heat Source

Abstract

As a new form of heat pump system, medium-deep ground source heat pump (MGSHP) systems designed to overcome the limitations of traditional heat pump systems, include the low efficiency, poor operational stability, and difficult startup of air source heat pumps in low ambient temperatures, as well as the low heat exchange intensity and large land use of shallow buried pipe ground source heat pumps, and difficulty in achieving 100% same layer recharge for groundwater source heat pump systems. Current research mainly focuses on the heating performance of a single system of MGSHP. However, in practical applications, using a single MGSHP heating system often results in partial load operation frequently during the heating season, leading to underutilization of the system’s capacity and poor economic performance. To address this issue, this study proposes a composite system combining MGSHP with an auxiliary heat source. But due to its short development history, optimized configuration designs remain underexplored. Therefore, this study establishes an optimization model for the composite system by simulating typical engineering projects using dynamic methods based on building heat load data. The model aims to minimize life cycle costs and simulates the optimal system design capacity. The results show that, under the conditions set in this study, the composite system of MGSHP combined with a gas boiler achieves the lowest average annual cost of 301,300 Yuan/Year and the design capacity of the MGSHP under the optimal capacity configuration takes up 54.69% of the total design capacity. However, in actual operation, the heat pump system prioritizes bearing the base load, and the proportion of the total cumulative heat load that the MGSHP system can bear during the heating season is 73.35%. This can serve as a valuable reference for practical engineering projects in terms of system capacity configuration.

Keywords: Medium-deep ground source heat pump, Auxiliary heat source, Composite system, Configuration optimization, LCC.