Field performance of gas-engine driven heat pumps in a commercial building

• Oversized heat pumps reduce the overall efficiency of GEHP systems.
• The study shows the field performance of GEHP systems in a commercial building.
• Technical and economic drawbacks of oversized HVAC systems configuration in commercial buildings are presented.

The aim of this study is to evaluate the field performance of gas engine driven heat pumps (GEHP) used in a commercial building. Four, 8 TR (cooling capacity) GEHP units were employed to provide air-conditioning to seven thermal zones in a commercial building. The performance of these GEHPs was assessed over a period of 10 months and compared with prior results reported in the literature. Additionally, this study provides a comparative economic analysis of GEHPs and conventional electrical heat pumps. During normal operation, the cooling capacity ranged between 12.3 kW and 19.3 kW. The average COPunit of these systems varied from 0.15 to 0.85 during field operation. The gas engines were found to operate at significantly lower loads than their design capacity, and therefore, produced overall lower efficiencies. Oversized GEHP systems were deployed to meet the low cooling/heating demands attributed to the lower overall field performance. This study demonstrates the importance of sizing the GEHP/HVAC system similar to the load in buildings.