Study On Exergy Of High Temperature Molten Salts And Their Corrosion Of Alloys In Argon Atmosphere In Concentrated Solar Power Stations

Due to the continuous exploitation of fossil fuels,it is imperative to find alternative energy sources.Solar energy as an easily accessible free and clean energy source is an excellent substitute for fossil energy.It can be used for energy conversion in solar thermal power stations and stably supplied.In order to ensure the stability of power supply research on the basis of heat transfer and heat storage in solar thermal power stations is indispensable.Heat transfer fluid circulation is one of the keys in solar thermal power plants.In order to achieve high efficiency and low cost,it is very important to choose a suitable heat transfer fluid.The molten salt mixture has a large operating temperature range high heat stable temperature low cost and environmental friendliness and is one of excellent materials for heat transfer fluids.In order to compare the thermodynamic performance of the heat transfer fluid the exergy concept is introduced to quantitatively describe the effective energy and efficiency of the heat transfer fluid cycle.Based on the second theorem of thermodynamics the mathematical model of exergy is derived.The exergy and system efficiency of the heat transfer fluids in the 50MW-capacity power plant are compared and the effective capacity of the molten salt is observed.Finally,the effect of the temperature range was extended to test its influence to effective energy of the molten salts in the heat transfer cycle and the thermodynamic performance of the nine molten salts.It is also a necessary research topic for the corrosiveness from HTF to the conveying pipe and the storage container material.The molten salts studied in this paper are highly corrosive to pipes which are usually alloys.It is critical to find the lowest corrosive combination.The corrosion properties of three molten salt mixtures and four common alloys at 700 °C are studied respectively.The samples after the experiment are analyzed by SEM EDS and XRD to study the corrosion principle between molten salts and samples respectively.The results show that the practical combinations are chloride with In718,In625,C276;carbonate with In718,SS316;fluorocarbon with In625,In718 respectively.This topic provides a data reference for the engineering application of concentrated solar thermal power station through the study of the thermodynamic properties and material corrosion of molten salts.They have important practical significance for the development of concentrated solar thermal power station.