Energy saving and economic analyses of design heating load ratio of ground source heat pump with gas boiler as auxiliary heat source

In order to make the best of the energy-saving of ground source heat pump (GSHP) and the lower initial cost of auxiliary heat source, the characteristics of energy saving and economy of GSHP assisted by gas boiler were investigated by numerical simulation and case study according to the weather data and fuel prices in some city of Xinjiang. The results show that if the design heating load distributes as 60% and 40% for GSHP and gas boiler respectively, the source energy consumption could not increase much more, however, the best economy is achieved for gas boiler assisted GSHP. In this case, the heat output of gas boiler forms only 8.3 percent of total heating output, and the total coal equivalent (CE) increased only 5.22% compared with the case of 100% design heating load supplied by GSHP, while the smallest present value of costs (249.3 RMB/m²) is acquired.