Scheme Design And Multi-criteria Comparative Evaluation Of CCHP System

This paper regarded the efficient utilization of energy, the lower environment emission and the higher economic benefit as foothold, viewed the system from the whole situation, built the system model, and then provided the assessment index, analyzes the performance of the system to compare and optimize.Firstly, aiming at the equipment composition and the workflow, this paper introduced the operating principle of system and equipment, provided the equipment energy-balance equations, the mass-balance equations, the medium properties equations, and the theory of electrochemical reaction, introduced the thermodynamic simulation software Cycle-Tempo, and the method of modeling by Cycle-Tempo.Secondly, the heating and cooling scheme of the Combined Cooling Heating and Power (CCHP) system was simulated and compare. The problems that come from the heat recover and the long distance transportation in the Combined Heat and Power (CHP)and Combined Cooling and Power (CCP) system. Aiming at these problems, the solution and strategy was put forward, the assessment index of thermodynamic and economy was given, and the assessment model was built. Then, on the basis of the current power plants, aiming at the configuration type of heating, four systems of CHP district heating schemes was put forward to analysis and compare. The model of four systems was built using the Cycle-Tempo to be simulated. The performance of thermodynamic and economy was analysis, the influence of nature gas price, the electricity price, the heating load and the heating distance on the economy was discussed. The CCP systems models was built using the Cycle-Tempo, the district cooling and the electric refrigeration was compared on the condition that power price was fixed, and the influence of the cooling distance on the economy was discussed. At last, the district cooling, the electric refrigeration and the ice storage were combined on the condition of peak and valley electric price, the economy of every scheme was discussed on the different cooling distance through eight cooling schemes.Thirdly, in order to improve the energy efficiency of CCHP system, the fuel cell was applied to the CCHP. Firstly, the SOFC system model was built using Cycle-Tempo, and the influence of SOFC pressure, SOFC temperature and current density on the system performance was analyzed. Then the SOFC and the gas-steam combined cycle (GT-ST) were combined. Three coupled systems were built on the basis of three patterns, the three systems were compared to select best one, and the influence of SOFC parameter on the best system power generation was analyzed. At last, the SOFC-GT-ST CCHP system and the general GT-ST CCHP system were built and analyzed.Fourthly, the multi-CCHP system schemes were optimized design and multi-criteria contrast analysis. According to different kinds of energy sources and different types of energy conversion and the configuration types of the heating and cooling, the design method of system schemes and select method were put forward. Specific to the general GT-ST CCHP system, the SOFC-GT-ST CCHP system and the biomass gasification GT-ST CCHP system, twenty system schemes were put forward, the model of each scheme was built by Cycle-Tempo. Then, the twenty schemes were assessed target the primary energy consumption, the annual total cost and the pollutant emission.