Field Investigation and Comparison Analysis of Low-Grade Heat Pump Technologies in Building Space Heating Projects

The building sector contributes a large ratio of final energy consumption, and improving building energy efficiency is expected to play a significant role in mitigating its carbon dioxide emission. Herein, we collected the on-site measurement data to investigate the techno-economic performances of different heat pump types that exist in building space heating projects in Qingdao, China. An in-depth analysis revealed the temperature varia-tions of measured low-grade heat sources over the whole heating supply period, and urban sewage water shows high stable heat energy quality compared with seawater and geothermal heat resources. Operational behaviors including cycling inlet and outlet temperature of the selected heat pumps were illustrated, and analysis evaluated detailed effects of operational parameters on energy efficiency performances. Then the relationship between COPs distributions of heat pumps and operational conditions was examined further, and the positive effect of the rising temperature of heat sources on energy efficiency improvement of heat pump is highlighted when the heating supply temperature is higher. Furthermore, we analyzed the economic and carbon emission performance of the heat pump system, and results show that electricity price plays a vital role in the lifespan energy cost saving potential, and the heat pump could serve as a promising approach in reducing CO2 related to the building space heating. Finally, we recommended suggestions for improving the overall energy efficiency and cost competitiveness of decentralized heat pump systems for building space heating. © 2022, Tech Science Press. All rights reserved.