Study On Heat Transfer Characteristics Of Volumetric Receivers With Water As Heat Transfer Fluid

A solid-liquid composite volumetric receiver using water as a heat transfer fluid and a porous material as a heat absorbing body,because of its high heat capacity,can ensure stable operation of the tower solar collector under complicated weather conditions.It has broad application prospects in the field of season heat storage and heating.However,the simulation model of this type of volumetric receiver is still blank,which brings difficulties to the operation prediction of the tower solar collector system and the thermal performance prediction of the volumetric receiver.This project relies on the solar energy season storage and heating system located in Fangshan Town,Zhulu County,Zhangjiakou City.The experimental study and theoretical analysis of the heat transfer characteristics of this new type of volumetric receiver are carried out.On this basis,a one-dimensional unsteady model of the volumetric receiver is established and the experimental results are used to verify it.Provide research tools for solar energy season storage system operation prediction.The verified model is used to analyze the influencing factors of the thermal performance of the volumetric receiver to provide theoretical guidance for the mechanism optimization of the volumetric receiver.The main findings of this paper are as follows:?1?An experimental platform for heat transfer characteristics of volumetric receivers was built.The experimental results show that the volumetric receiver maintains stable operation under complex weather conditions,ensuring that the volumetric receiver outlet temperature is above 50°C.?2?Based on theoretical analysis and experimental research,a one-dimensional unsteady model of volumetric receiver is established.The equations in the model are discretized by the control volume balance method,and the discrete equations are used MATLAB software to solve.The one-dimensional unsteady model of the volumetric receiver was verified by experiments.The relative error between the simulated value and the experimental value was less than 10%.?3?Using the one-dimensional unsteady model of volumetric receiver to analyze the influencing factors of the thermal performance of the volumetric receiver,respectively study the distribution of solar radiation energy density,wind speed,extinction coefficient,ambient temperature and flow rate.It is found that when the extinction coefficient and wind speed have a significant effect on the thermal efficiency of the volumetric receiver,when the wind speed increases from 0 m/s to 10 m/s,the convective heat transfer coefficient between the light window of the volumetric receiver and the outside air is The increase was 83.7%,the thermal efficiency of the volumetric receiver decreased by 7.8 percentage points;when the extinction coefficient increased from 0 m^-1 to 10 m^-1,the average temperature difference between the light window of the volumetric receiver and the air increased by 4°C.The thermal efficiency of the volumetric receiver decreased by 6.1 percentage points.