Performance Analysis And Optimization Of A Solar-driven Organic Rankine Cycle

Solar energy is one of the cleanest energy sources.The huge energy and almost no geographical restrictions make it available in a variety of forms.Among them,solar ventilation and heat collection technology is widely used in green buildings,and this technology is accompanied by a heat collection system.The medium and low temperature waste heat of the outlet air is produced.The organic Rankine cycle system based on the traditional Rankine cycle,which uses low-boiling organics instead of water vapor as the system circulating working fluid,has the characteristics of being driven by a medium and low temperature heat source and simple in structure.Therefore,considering the combination of the two in green buildings to realize the energy conversion of light-heatelectricity is of great significance for the energy cascade utilization and improvement of the energy structure.Choose a simple solar chimney wall type ventilation heat collection structure to cooperate with the basic organic Rankine cycle system.Due to the characteristics of solar radiation intensity changing with time,in order to ensure the stable operation of the overall system,a heat storage device needs to be added between the two system units.Then,according to the heat transfer mechanism and the laws of thermodynamics,the corresponding mathematical models are established.Among them,the calculation models of the organic Rankine cycle system include thermodynamic models and economic models.According to the established model,FLUENT and MATLAB are used for simulation calculation.The content includes: the layout parameters of the solar ventilation heat collection system unit and the simulation of the outlet air temperature based on this layout;the different working conditions(evaporation temperature,evaporation)in the organic Rankine cycle system Important operating parameters such as pressure and condensation temperature)cause changes in system performance(thermodynamic performance and economic performance)and perform corresponding sensitivity analysis to obtain operating parameters that should be considered first when optimizing different performances.In order to further optimize the performance of the organic Rankine cycle system,in addition to considering the effect of the heat source temperature on it,the system performance of a single working fluid and a working fluid with different mixing ratios was further compared.The results show that the mixed working fluid is not necessarily better than the single working fluid.It is affected by the mixing ratio,operating parameters and the physical properties of the mixed organic working fluid.According to the above simulation results,response surface method and genetic algorithm are used to calculate multi-objective(thermodynamic performance and economic performance)optimization,and finally a Pareto optimal solution set suitable for engineering problems is obtained.