Energy and Exergy Analysis of China’s Distributed Combined Heating and Power with Heat-Pump Heating for Peak Shaving

Abstract

China has been vigorously developing natural gas-based urban district heating (UDH) for years to reduce severe air pollution. In this paper, energy and exergy analysis methods are applied to distributed combined heating and power with heat pump heating for peak shaving (DCHP + HPH) in five representative UDH cities in China. Effects of a peak shaving ratio (a ratio of the maximum heating load undertaken by heat pump heating to the maximum design heat load of the UDH system) on gas turbine load rate, primary energy ratio and exergy efficiency of the DCHP + HPH are investigated. The analysis results show that when the peak shaving ratios are in the range of 0.3–0.4, the average exergy loss of gas turbine can be reduced by approximately 25%, and the maximum average exergy efficiencies of the DCHP + on-demand HPHs in the five representative UDH cities reach approximately 50–51.4%. This optimal natural gas-based UDH should be promoted in China instead of natural gas-fired heating boilers to replace coal-based UDH.