Numerical Simulation Of A Novel Thermochemical Heat Storage Reactor Based On Hydrated Salt

Thermochemical heat storage technology（TCS）has gained considerable attention of many scholars owing to its high heat storage density and long-term storage without wasting heat,but it is still in the laboratory research stage due to its complex technology and large one-off investment.The paper proposed an open fixed bed that can transmit moist air through multiple channels to address problems of uneven reaction in traditional stacked packed bed reactors,and the easy deliquescence and liquefaction of reaction materials,which results in mass transfer deterioration.Selecting the salt Sr Br₂·6H₂O/Sr Br₂·H₂O as the reaction material,a physical and chemical model of the reaction salt dehydration and hydration reaction in porous media was established,and the coupling mechanism of chemical reaction,mass transfer and heat transfer between porous material and fluid in the reactor was revealed;the effect of different operating conditions（inlet air temperature,inlet air velocity,inlet water vapor partial pressure,reaction material porosity and permeability）on the reaction process was explored,and the evaluation indicators such as thermal efficiency,comprehensive energy efficiency,thermal power,energy density and reaction time were used to judge the performance of the reactor under different working conditions.The results show that the thermal charging and exothermic efficiencies of the reactor under the reference conditions are 86.34%and 77.09%respectively,the dehydration and hydration reaction times are 15.4h and 78.3h respectively,the comprehensive energy efficiency is 66.24%,and the energy storage density reaches 1.4GJ/m³.Additionally,the study found that increasing the inlet air temperature and inlet air flow rate can speed up the heating reaction rate,and a slightly lower ambient temperature and inlet air flow rate are conducive to heat release in winter and meet the needs of domestic heating and domestic hot water.The regulation of water vapor partial pressure has little effect on the rate and thermal efficiency of the dehydration（charging）reaction,but essential for hydration（exothermic）reaction.The higher the inlet water vapor partial pressure,the faster the hydration reaction rate,thus the exothermic efficiency and the temperature rise between the inlet and outlet also grow gradually.Increasing the porosity of reactive materials facilitates the rapid diffusion of vapor and accelerates the hydration reaction rate,but also reduces the energy storage density and thermal exothermic efficiency.The permeability of the reaction material will directly affect the pressure drop of the reaction bed,which has little effect on the reaction rate and the heat transfer performance.In the structural optimizations of the reactor,it was found that increasing the length of the outflow channel h _a could effectively improve the reaction rate and thermal efficiency,and 0.17m is the optimal outflow channel length with analysis.