| With the implementation of China’s 13th Five-Year Plan green development is becoming the themes of the development of the time.From the perspective of energy consumption,the radiation-convection air conditioning system with great energy-saving potential,is quite promising in solving energy problems in China.In this paper,the debated issues about the combined radiant floor and fan coil cooling system are investigated via a combine cooling experiment platform set up in Jinan the capital city of Shandong province in China,which is located in a climate zone with cold.Firstly,we built a 4 m×2.8m×3 m experimental room and completed the layout construction of a combined cooling automatic operation system based on outdoor weather conditions and the installation of a data monitoring system.During the experiment,we measured the temperature and flow rate of radiant floor and fan coil supply and return water,floor surface temperature,indoor air temperature and humidity,mainframe supply and return water temperature and indoor non-cooling wall temperature.Analyzed the indoor temperature change,the floor surface temperature change and the floor surface temperature change after the combined cooling system stop.The results we obtained were as follows:（1）the time duration required for the water supply temperature on the floor to reach a relatively stable state was about 2～3 times higher than that of the fan-coil.（2）the combined cooling system didn’t perform well in dealing with indoor heat load in the start-up stage.（3）The linear fitting ofτ63 andτ95 relation was verified by the data on August 24 and through the linear fitting we obtained a relation with certain accuracy.The radiant floor temperature change after the shutdown of the combined cooling system conformed to the law of exponential growth for first-order functions.Secondly,through the influence of the change in indoor load and water supply temperature on indoor temperature change trend,the following were found:（1）Radiant floor has great thermal inertia,which inhibits the effect of indoor load step change on the surface temperature change of radiant floor to a certain extent.The radiant floor has good thermal stability.（2）The fluctuation of the temperature of each wall is small,the temperature of each non-cooling wall is less affected by the change of the water supply temperature.The stabilizing effect of the radiant floor on the indoor environment is stronger during the intermittent operation.Then,we studied the calculation method of cooling capacity of radiant cooling system and vertical air temperature and each non-cooling surface temperature.The results showed that（1）The non-cooling surface temperature was relatively stable.The influence of outdoor meteorological conditions on the temperature of the inner roof was greater than that of other except the inner roof.（2）When the fan coil stopped,the total heat transfer coefficient of radiant floor,radiant heat transfer coefficient and convective heat transfer coefficient varied from5.552～6.102 W/m~2·K,4.788～5.169 W/m~2·K and 0.288～0.363 W/m~2·K respectively.The variation range of total radiant floor cooling capacity,radiant floor cooling capacity and radiant floor convection cooling capacity were 5.74～26.41 W/m~2,4.86～20.62 W/m~2 and 0.43～1.28W/m~2.The proportion of radiant floor convection cooling capacity（about 4.85～7.47%）was small.The relationship between total cooling capacity,radiant cooling capacity and radiant floor convection cooling capacity and their reference temperature difference described as Qfloor=6.061(TOP0.6-TS),Qr=4.787（Aust-TS）and Qc=0.335(Ta1.1-TS).Finally,analysis of the cooling capacity of the combined cooling system under different outdoor weather conditions.The cooling capacity of fan coil unit accounted for 65.6～76.2%of the total cooling capacity.The outdoor weather conditions have a more obvious effect on the fan coils.The higher the outdoor temperature and humidity,the greater the proportion of fan coil cooling capacity to the total cooling capacity.Concerning the influence of different outdoor meteorological conditions on the combined radiant floor and fan coil unit cooling system,this paper provides a reference basis for the promotion and application of the combined cooling system in Jinan,Shandong province. |
