Numerical Simulation Of Multi-module Thermochemical Heat Storage Reactor Based On Hydrated Salt

The intermittence and instability in solar energy generation can be solved by heat storage technology,which is an important part of concentrated solar power generation.Comparing with sensible heat storage and latent heat storage,chemical heat storage has the advantages of high heat storage density.long storage time,and long transport distance,and then has great potential to development.In this paper,researches of chemical heat storage reactors are done mainly by numerical simulation method.This paper firstly designs a multi-module chemical heat storage reactor using hydrated salt as thermochemical heat storage material,and builds the structure model and numerical model of the reactor.ANSYS Fluent is used to analyze and study the performance of the multi-module chemical heat storage reactor.The structure model consists of three parts:the heat transfer fluid,the hydrated salt module and the metal plate.Numerical model includes governing equations and chemical reaction model.The reaction model is realized by programming UDF files.After verifying grid independence and the experimental results,the changes in the temperature field,dehydrate speed field,dehydrate rate field and water vapor mass fraction field of the reactor by time during the heat storage process are analyzed and studied.The results show that the whole process can be divided into four stages:heating stage,fully reaction stage,completing reaction stage and ending stage.Secondly,the influence of various variable operating conditions on the reactor is discussed.By studying the changes in the dehydrate speed and dehydrate rate at the seven monitoring points and the outlet temperature of the heat transfer fluid under various operating conditions,the initial reactor temperature,the inlet temperature and velocity of the heat transfer fluid,and the inlet temperature and velocity of the air inside the reactor are analyzed.The results show that increasing the initial temperature of the reactor,increasing the inlet temperature and velocity of the heat transfer fluid,and preheating the air in the heat storage module can increase the dehydrate speed,while the inlet temperature and velocity of the heat transfer fluid have the greatest impact on the dehydrate speed;Increasing the air flow rate inside the heat storage module can reduce the temperature of the heat transfer fluid outlet and reduce the heat loss of the system.Finally,the influence of the structural parameters on the reactor are discussed,including the air and heat transfer fluid flow direction in the reactor,the length and width of the reaction module,the thickness of the metal plate,the width of the heat transfer fluid channel,and the porosity of the hydrated salt particles.Basing on the analysis of the dehydrate speed,the dehydrate rate and the outlet temperature of the heat transfer fluid under different structural parameters,the influence of these structural parameters on the reactor is studied.The results show that the structure has the fastest dehydrate speed where the heat transfer fluid is upward while the air is downward,and the structure has the highest dehydrate rate where the heat transfer fluid is downward while the air is upward;reducing the porosity,the width of the module or the thickness of the metal plate will increase the dehydrate speed;increasing the length of the heat storage module,reducing the width of the heat storage module or the thickness of the metal plate will increase the final dehydrate rate;and reducing the width of the heat transfer fluid channel can reduce the outlet temperature of the heat transfer fluid.