Thermoeconomic Analysis On The System Of Micro Gas Turbine Integrated With Organic Rankine Cycle

Now, China faces the serious problem of the resources and the environment pollution, improving the energy efficiency and energy saving have become the shared challenge to all of us. The Combined Heating and Power(CHP) system composed by the Micro Gas Turbine(MGT) has attracted much more attention since it has the advantages of high efficiency, less pollution and especially it is suit for the micro distributed energy system. However, the temperature of the exhaust gas from the micro gas turbine is medium or low; thus, people pay much attention on how to make good use of these part energy for improving the energy efficiency. While, the Organic Rankine Cycle(ORC) has high availability and promising future for recovering low or medium waste heat, it has a great significance for improving energy efficiency and ecological environment.Therefore, the combined heating and power system of the micro gas turbine integrated with the organic Rankine cycle is proposed in this paper. The parametric analyses from the viewpoint of thermodynamics and thermoeconomics have been performed on the CHP system using the EES software. The main contents of this paper are summarized below:Firstly, the principle of the ORC system and fluid selection are introduced, the parameters of the heat source inlet temperature, evaporation temperature and pinch point temperature difference are considered and their influences on the performance of the ORC system using four kinds of working fluids are studied. By comparison, Toluene is selected as the working fluid of the bottoming ORC system. Secondly, the principle and mathematical model of the CHP system are introduced. The energy utilization efficiency and exergy efficiency are increased to 76.79%, 36.09% at the design condition, respectively. Meanwhile, the influences on the thermodynamic efficiency of the proposed system by the pressure ratio, gas turbine inlet temperature and evaporation temperature are also studied. Thirdly, the basic theory of thermoeconomics is introduced, the thermoeconomic mathematical models based on “exergy” cost and “monetary” cost are developed. The results show that the thermoeconomic cost of the thermal energy is higher than the electricity. In addition, the influences on the thermoeconomic indicators of the system by the parameters mentioned above and the causes of the variation are analyzed, the measures for improving the thermoeconomic performance of the system are proposed at the same time.The results obtained in this paper have some significances for guiding the design and optimization of the MGT- ORC system; it will be benefit for promoting the engineering application of the proposed CHP system and the analysis method of thermoeconomics.