A feasible system integrating combined heating and power system with ground-source heat pump

• CHP system based on natural gas and ground source heat pump.
• The new system can make a better utilization of waste heat in flue gas by a special way.
• The proposed system can realize energy saving potential from 0.8 to 34.7%.
• The coefficient of performance of ground source heat pump subsystem is significantly improved from 3.5 to 3.6–6.
• Warm water temperature and percentage of flue gas used to reheat are key parameters.

A system integrating CHP (combined heating and power) subsystem based on natural gas and GSHP (ground-source heat pump subsystem) in series is proposed. By help of simulation software-Aspen Plus, the energy performance of a typical CHP&GSHP-S (S refers to ‘in series’) system was analyzed. The results show that the system can make a better use of waste heat in flue gas from CHP (combined heating and power subsystem). The total system energy efficiency is 123% and the COP (coefficient of performance) of GSHP (ground-source heat pump) subsystem is 5.3. A referenced CHP&GSHP-P (P refers to ‘in parallel’) system is used for comparison; its total system energy efficiency and COP of GSHP subsystem are 118.6% and 3.5 respectively. Compared with CHP&GSHP-P system with different operating parameters, the CHP&GSHP-S system can increase total system energy efficiency by 0.8–34.7%, with related output ratio of heat to power (R) from 1.9 to 18.3. Furthermore, the COP of GSHP subsystem can be increased between the range 3.6 and 6, which is much higher than that in conventional CHP&GSHP-P system. This study will be helpful for other efficient GSHP systems integrating if there is waste heat or other heat resources with low temperature.