| As a kind of air-conditioning equipment,air-conditioning system aims to provide a comfortable indoor environment to meet the environmental needs of indoor personnel for working and living.Besides,as a new type of air-conditioning system,radiant heating and cooling system has attracted the attention of a large number of experts and scholars.Radiant ceiling heating and cooling system,as a typical terminal of radiant heating and cooling system,is widely used in existing buildings.Compared with the traditional convective air-conditioning system,radiant heating and cooling system has the advantages of better comfort,larger energy-saving potential and lower indoor noise.However,the existing studies rarely objectively compare the energy consumption level and thermal environment difference between convective air-conditioning terminal and radiant system terminal combined with real time and field conditions.Meanwhile,there is litter research on the interaction between the terminal of the radiation system and different transparent envelopes(external windows).In addition,the comparative research on the performance differences of the terminal of radiant system in different types of rooms is inadequate.Therefore,it is necessary to deeply explore the energy consumption and thermal environment of the terminal of the radiant heating and cooling system(radiant ceiling system)under the conditions of different building envelopes and different room types.According to the existing research background,this paper carries out a series of experimental research and numerical simulation on the radiant ceiling heating and cooling system.Firstly,through comparative experiments,this paper studies the energy consumption difference between the terminal of radiant system(radiant ceiling system)and convective air-conditioning system(fan coil)under the same thermal comfort benchmark.What’s more,this paper studies the energy consumption and thermal environment level of the radiant ceiling system under different external windows(ordinary uncoated insulating glass window,heat reflection insulating glass window and triple silver Low-E insulating glass window).And the paper takes five typical city of different thermal zones in China as the research object,analyzes the applicability of the system in different climatic regions of the country,and evaluates the application potential of the radiant ceiling system under different transparent envelope conditions.Finally,taking a complex building for flight zone management as the experimental object,the energy consumption and indoor thermal environment level of radiant ceiling system in four different types and functional rooms(restaurant,office,lighting control room and conference room)are studied and compared.The results show that under the same operative temperature,the radiant ceiling terminal(RC terminal)can save 26.53% and 34.75% of energy consumption compared with the convective air-conditioning terminal(CAC terminal)in the cooling and heating test periods,respectively.Meanwhile,the air temperature of the RC terminal room is 2.4 ?C higher than that of the CAC terminal room for cooling season and 2.2?C lower for heating season.The vertical temperature gradient distribution of the RC terminal room is 0.6–1.5 ?C/m,which is only 27.5% of that of the CAC terminal room.Moreover,the horizontal temperature fluctuation of the RC terminal room is only 1/3of that of the CAC terminal room.Therefore,as for considering energy consumption and indoor thermal comfort level,the RC terminal outperforms than the CAC terminal.Taking the annual air conditioning energy consumption of ordinary uncoated insulating glass window(OIG)as the comparison standard,in five climate regions of China,the energy-saving rates of heat reflection insulating glass window(HFIG)and three silver Low-E insulating glass window(TSIG)in radiant ceiling heating and cooling system rooms are-9.78%,0.27%,21.46%,30.73%,48.00% and 8.82%,15.67%,42.57%,57.73% and 63.65% respectively.Moreover,there is a significant difference in the average indoor temperature between uncoated OIG window room and coated glass window(HFIG and TSIG)rooms.When the solar radiation is strong,the temperature difference is as high as 2 ℃-4 ℃.Therefore,for the buildings,radiant ceiling heating and cooling system as an energy-saving air-conditioning system,considering the overall energy consumption and thermal environment of the building,different transparent envelopes should be matched for different climate zones.For areas where cooling is dominated,both HFIG and TSIG windows can save a lot of airconditioning energy consumption,and the specific selection of these two kinds of windows should consider different building types and construction costs.For areas where heating is the dominated,the TSIG window should be preferred to,and the HFIG window with heat reflective coated should be avoided.There are some differences in terms of the indoor thermal environment of different types of rooms at different times.The results show that the factors such as solar radiation,outdoor cold air infiltration,and personnel flow are the main causes of indoor thermal environment fluctuations.Cold air infiltration has a great impact on the overall performance of radiant ceiling heating system.Affected by cold air infiltration,the indoor air temperature of the restaurant fluctuates greatly in a certain period,and the maximum temperature gradient reach as high as 3.5 ℃ / m at the height of 0.1m-2.0m.On the whole,according to the use of radiant ceiling system in different types of rooms(large space,small and medium-sized space),it can be seen that the radiant ceiling system has lower average energy consumption level and better indoor thermal environment in large space rooms.Therefore,radiant ceiling system is more suitable for large space rooms.By studying and comparing the energy consumption and thermal environment levels of different air-conditioning system terminals(CAC terminal and RC terminal)and radiant ceiling system under different transparent envelopes(external windows)and different types of rooms,this paper makes up for the research gap in the field of radiant heating and cooling system.Besides the paper systematically discusses the different changes of radiant ceiling system performance under different building envelopes and types of room,and analyses the applicability of radiant ceiling system in different climate regions.The research results provide reference for researchers and practitioners on the performance of radiant ceiling system under different building envelopes and different types of rooms(different terminals of air-conditioning system,different transparent envelopes and different types of rooms). |
