Simulation Study On Heating Performance Of Corrugated Convection-radiation Wall Panel

In recent years,China has vigorously promoted the development of clean heating in rural areas,mainly using renewable energy sources,to improve the indoor thermal comfort of rural residents in winter and enhance the atmospheric quality and beauty of the countryside.The combination of clean heating and efficient heating end-use can improve the energy utilization efficiency of the heating system.However,traditional heating end-use requires high water supply temperatures.Moreover,due to the scattered living functional areas in rural areas,residents move in and out of various rooms,and cold air intrusion can easily cause indoor temperature fluctuations.Therefore,this paper proposes a convection radiation type wall panel heating end-use with a radiation surface in the shape of a triangular wave.The wave-shaped surface increases the working area and improves the convective heat transfer coefficient,making it possible to meet indoor heating demands with lower water supply temperatures.Forced convection can also quickly increase room temperature,thus achieving the goal of improving energy utilization efficiency and satisfying indoor thermal comfort.To explore the heat transfer performance of the wall panel and its impact on the indoor thermal environment,this paper uses a physical model and numerical simulation method to conduct the following research on the wall panel.First,the shape of the triangular wave(wave length L and wave angle β)is analyzed.The influence of L and β on the wall panel’s heat transfer capability is simulated,and the distribution of natural convection heat transfer,radiation heat transfer,indoor temperature,and velocity under various conditions is analyzed.The results show that all heat transfer quantities of the wall panel increase with a decrease in L and a smaller β.Taking into account the heat transfer performance and aesthetic considerations of the wall panel,five sets of working conditions with different β values are studied while keeping the length of the triangle’s base unchanged at 50 mm.After analysis and comparison,β is finally determined to be 60°.Second,the height,thickness,and spacing of flat fins inside the air channel of the wall panel are studied through simulation.The heat transfer performance of each structural dimension is comprehensively evaluated,and changes in pressure loss and air-side convective heat transfer coefficient are analyzed.To explore the optimal combination of each structural dimension based on the comprehensive evaluation index of heat transfer performance(PEC),a three-factor,three-level orthogonal table is established with fin height,thickness,and spacing as influencing factors.By conducting a range analysis of the results,the optimal fin dimensions are determined to be: fin height of 45 mm,fin thickness of 1.0 mm,and fin spacing of 30 mm.Finally,the simulation study of wall panels with forced convection was carried out based on the previous research.The effects of different air supply velocities and changes in wall panel temperature on the heat transfer performance of the wall panel and indoor thermal environment were explored.The results show that the air supply velocity has a significant impact on the heat transfer performance of the wall panel.The total heat transfer of the wall panel increases with the increase of air supply velocity,mainly because the forced convection heat transfer increases significantly with the increase of air supply velocity.The proportion of forced convection heat transfer to total heat transfer under different air supply velocities is 49.55%,58.56%,64.19%,and 68.10%,respectively.When the air supply velocity is greater than 1.2 m/s,indoor air circulation is formed,and a thermal air curtain is formed on the south exterior wall,effectively improving indoor thermal comfort.The temperature of the radiant wall panel has a greater impact on the total heat transfer,but the increase in each heat transfer with the increase of radiant panel temperature is relatively small.The change of wall panel temperature has a small effect on the proportion of forced convection heat transfer to total heat transfer(58.56%,56.80%,55.80%).The vertical temperature difference inside the room is small,with a maximum value of ΔT = 0.46 ℃,and the wind speed in the main activity area of the human body is low.Overall,the wall panel meets the thermal comfort requirements of the human body under various working conditions.This research provides a feasible reference solution for the selection of rural heating end-points and provides a reference for the practical application design of radiant wall panels.