Study On A30MW CCHP System Assisted With Solar Energy

Over the past two centuries, the energy system based on fossil fuels has greatlypromoted the development of the mankind but also leads to complex environmentaland social problems. In the context of energy crisis, solar energy attracts greatattention from each aspect of the society due to its opposite characteristics comparingto fossil fuels. While compared to the electricity driven chiller, absorption chiller useslow temperature heat to generate cold, which can be used for heat recovery from thelow temperature heat source and reduce electricity consumption.Based on a30MW coal fire power plant, a combined cooling, heating and powersystem integrated with solar energy and LiBr absorption chiller is proposed. At first,solar resource and heat/cold need are analyzed for different regions of China. Resultsshow in Southern China, direct solar irradiance is relatively low due to the climate butvery high cooling need exists, which makes this region suitable for CCHP systemintegrated with solar energy especially for300-600W/m~2. Secondly, heat transferprocess in the solar field is analyzed and models for concentrated solar field, coalcombustion, steam cycle and LiBr absorption chiller are established aftermathematical analysis. The models are validated with low difference to the referencedata. What’s more, results show that when the inlet temperature increases andtemperature difference keeps constant, reduction on net efficiency of solar field isseverer for low irradiance condition than the higher one. At last, different operationschemes are proposed based on different irradiance considering the mass flowconstraint of the solar field. The schemes are: non-irradiation condition, insufficientirradiation condition and sufficient irradiation condition. The results show that, theprimary energy efficiency and fossil fuel conservation ratio will increase with theincrease of the mass flow of the steam for the absorption chiller while the electricitygeneration is on the opposite. In the time of insufficient irradiation, the inlet and outlettemperature for the solar field is110/200℃, and η as well as F will increase with thesolar irradiance. The inlet and outlet of oil are set as293/391℃for high irradiancesituation. The irradiance increases, the electricity generation will increase as well.When direct solar irradiance reaches900W/m~2, extra electricity can be as high as8.2MW.The special job for this paper is the different operation choice for the CCHPsystem based on the range of direct solar irradiance, which can provide guidance tothe utilization of CCHP system integrated with solar energy in Southern China.