Comparison on energy consumption evaluation methods for CHP plants under off-design working conditions

抄録

Coal takes a big portion of power generation in many developing countries, and efficiency enhancement of coal utilization is very important for the sustainable development. Combined heat and power (CHP) is an effective way to enhance the efficiency of coal-fired power plants. Moreover, the cogeneration of heat and power can bring remarkable economic benefits for power stations. The energy consumption evaluation to express the efficiency of CHP plants is a traditional but also a reserved issue that needs to be addressed, which is very important for the design, operation, and energy saving evaluation of CHP plants. In this study, the off-design calculation models of CHP unit were developed. With a reference case, efficiency to produce thermal energy and power under variable heat and power loads were studied. Three tradition energy consumption evaluation methods were compared when the unit operates under the off-design conditions. The exergy loss and dissipation of the case unit under the off-design conditions are shown. This study may provide a reference for the development of energy consumption method for CHP plants.