Study On Cooling Performance Of The Convection-radiant Wall Panel

In recent years,the air-conditioning cooling system includes central air conditioning or split-type air conditioning cooling based on convection heat exchange,and radiant cooling panel based on radiative heat transfer.In order to combine the advantages of the two cooling methods,scholars at home and abroad have proposed a variety of composite air conditioning cooling systems that combine convection and radiative heat exchange.However,the disadvantage of the composite system is that two sets of air conditioning systems requires higher operating costs.Therefore,this topic proposed a convectionradiation wall panel,which effectively combines two heat exchange forms in one system,and studied its cooling performance parameters and indoor thermal environment changes respectively in pure radiation mode through experimental testing and forced convection + radiation mode through numerical simulation,and analyzed the load adaptability of the wall panel in different conditions through theoretical calculations,to provide a reference for practical engineering applications.First,a convection-radiation type wall panel cooling experiment platform was designed and built,and equipment selection,experimental measurement point arrangement and temperature sensor calibration were completed.In the artificial microclimate laboratory,the cooling performance test of the convection-radiation wall panel in pure radiation mode was carried out to study the cooling performance of the wall panel and the change of the indoor thermal environment when the indoor air reached different states.The experimental results showed that: the higher the water supply temperature,the longer the time required for the indoor air to reach the design temperature of 26 ?,the higher the average surface temperature of the wall panel,and the smaller the heat exchange of the wall panel;when the water supply temperature is 18 ?,it takes about 4 hours until the indoor air reaches a stable state,the average temperature of the indoor working area is 24.7 ?,the total heat exchange of the wall panel is 131.5W,the three heat exchanges are less than the value when the air reaches the design temperature,and the indoor vertical temperature difference and PMV value both meet the comfort requirements.Secondly,the CFD numerical simulation was used to study the cooling performance and indoor thermal environment of the wall panel in the forced convection + radiation mode,and to explore the influence of the air supply speed and the surface temperature of the cooling panel.The simulation results showed that the cooling performance of the wall panel increases with the air velocity,and decreases with the surface temperature of cooling panel.When the air supply speed is 1.0m / s,the surface temperature of cooling panel is 22 ?,the indoor PMV value is 0.1 with the best thermal comfort;when the surface temperature of cooling panel is 18 ?,the total heat exchange of the wall panel increases by 44.6% after the introduction of forced convection.The indoor temperature and wind speed distribution are more uniform,and the thermal comfort is improved.Finally,the load adaptability of the wall panel was analyzed through theoretical calculations.The results showed that: When the supply air velocity is 1.0m / s in forced convection + radiation mode,the wall panel can meet the fresh air cooling load in mild region and severe cold region with strong load adaptability,while in hot summer and cold winter region and hot summer and warm winter region with weak load adaptability.With introduction of the fresh air system,the greater the proportion of the fresh air system to bear the cooling load,the faster the theoretical area of the wall panel decreases,and the smaller the metal consumption of the radiant panel,so as to the more adaptable the load per unit area.