Application Research On Floor Radiation Cooling System In Residential Buildings In Chongqing

Radiat cooling/heating technology has gained more and more recognition due to its advantages of comfort,efficiency and aesthetics.Floor radiant heating technology has been widely used.However,in practical application of floor radiant cooling system,there are many problems such as high energy consumption in continuous use,long cooling time in intermittent use and condensation problem caused by unreasonable operation strategy.Therefore,in order to solve the problems of floor radiant cooling in residential,connected with office worker family schedules,this article analyses the heat transfer process of floor radiant cooling system,indoor thermal comfort,cooling time,the key operation parameters and the energy consumption of different energy modes in the conditions of different supply water temperature and supply air in the methods of theoretical analysis,experimental research and numerical simulation.Firstly,the heat transfer process and comfortable temperature of floor radiant cooling system are described.The acceptable upper limit temperature?30??,comfortable upper limit temperature?28??and comfortable neutral temperature?27??has been cleared.The target temperatures for circumstances of cooling before or after people enter have been defined.Then,under the experimental condition of 4.5m²/person,in the moisture production view of 1 person,cooling time and indoor comfort are contrasted in different water temperature?14?,16?and 18??and different air supply conditions?1.5ach and2ach?.Then,according to the residential about 9 m²/person,supply air energy in the conditions of 0.7ach,1ach,1.5ach and 2ach with 18?supply water is simulated and calculated by Fluent.Finally,all night temperature and energy consumption of different energy modes in residential are simulated in the best supply water and air parameters.The experiment shows that:for the cooling ahead circumstance,only radiant cooling need 40⁵0 min to acceptable upper limit temperature 30?,and 82¹06 min to comfortable upper limit temperature 28?.Only fresh air cooling need 24min to 30?and58min to 28?.For the radiant and 2ach supply air cooling condition,18²6min is needed to be cooled ahead to the acceptable upper limit temperature and 42⁴6min to comfortable upper limit temperature.For the circumstance of cooling after people enter,with the same supply water temperature,radiant and 2ach supply air condition cool22²8min to acceptable temperature and 64⁶7min to comfortable upper limit temperature while for radiant and 1.5ach condition,it is 30³5min to acceptable range and 60⁶4min to comfortable upper limit.By the analysis,the supply air has a larger influence on cooling time of coupled cooling system than supply water temperature and the continuous air can strength floor cooling ability.The indoor load significantly affects the drop rate of space operating temperature,but has little effect on radiant cooling ground.In comprehensive comparison of indoor comfort and cooling time,radiant+supply air is the best cooling way and 18?is the most suitable supply water temperature.Theoretical calculation shows that:the supply air quantity has a greater influence on the supply air energy consumption than the supply air temperature and the supply air consumption with smaller air volume is less under the same dehumidification.Compared with 2ach condition,the 0.7ach,1ach and 1.5ach conditions can save energy by 48%,37%and 17%respectively.Simulation results show that:the energy consumption of cooling system per unit construction area of the whole night under different energy modes is 0.11⁰.16 kWh/m^2.It is recommended to use separate energy mode and standard energy mode in terms of whole night energy and the cooling time to acceptable and comfortable upper limit temperature after people enter rooms.For the standard energy mode,the living room,second bedroom and the master bedroom are cooled at 19:00,20:00 and 23:00 respectively.For the separate mode,from 19:00 to 23:00,only the living room is cooled and only bedrooms will be cooled after 23:00.The supply air energy consumption accounts for 72%⁸4%of the total energy consumption.The energy consumption of constant frequency water pump,accouting for 54%⁶2%of the total water system energy consumption,is larger than that of variable frequency refrigeration unit.The energy consumption can be effectively reduced by 17%³3%by adjusting the supply air volume of each room and unit.