Study On The Heating Process And Dynamic Response Of Intermittent Cooled Room With Tubes-embedded Building Envelope Cooling System

Tubes-embedded building envelope cooling system is also called thermally activated building system(TABS).The biggest difference between tubes-embedded building envelope cooling system and other radiant cooling system is that,for TABS,water tube is embedded in concrete layer of building envelope.So building envelope can directly be involved in the indoor air conditioning as a part of the air conditioning system,and the thermal effect of envelope structure will directly affect the system's cooling performance and the operation and regulation.The thermal storage effect of the floor structure is the advantage of the TABS system and use the building's thermal mass to flatten out the peak cooling load,reduce chiller capacity and reduce the initial investment.However,the existence of the thermal storage can affect the control of system that can not achieve timely and increasethe difficulty of system operation.But it is precisely because of heat storage effect,makes intermittent operation possible in order to achieve energy-saving effect.To accurately formulate the intermittent control strategy and set parameters,it is necessary to analyze the heating process and dynamic response of thermal environment in the intermittent cooling system.In this paper,the office building was used as the research object,and using TRNSYS simulation as the research means to build a typical office building model,in which the the tubes-embedded building envelope cooling system combined with dedicated outdoor air system were employed as the air-conditionning system.Based on this system and simulate,thermal environment response characteristics and influencing factors of tube-embedded envelope radiation cooling system were analyzed.Finally,from the geometric structure and the thermophysical performance level of the cooling components and passive walls,the influence factors of the dynamic response of the room was analyzed and the obvious influencing factors were found out.The main conclusions are summarized as follows.(1)Simulated the thermal response characteristics of cooling components and passive walls to analyze the change of temperature and heat flux density.(2)Compared the effects of different cooling times on indoor air temperature and the heat flux,and discovered eight-hour cooling time can meet the indoor thermal environment of the typical office buildings in Xi'an.It was also found that there should select short cooling time considering the double target of comfort and energy saving.(3)Compared the effects of the same cooling time with different cooling period on the cooling system performance,and found that start and stop mode frequently(cooling time: 1: 00-2: 00,3: 00-4: 00,5:00-6: 00,7: 00-8: 17:00: 00-18: 00,19: 00-20: 00,21: 00-22: 00,23: 00-0: 00)have more advantage than other cooling mode.It should use night cooling mode(0: 00-8: 00)when consider energy-saving.(4)Thermal environment dynamic response factors in the room was analyzed,and discussed the effect of cooling system buried pipe parameters(buried tube spacing,borehole depth and the thickness of insulating layer)on the room air temperature and heat flux.While the effects of cooling components and passive walls thermal parameters on heat flux were also discussed.(5)It was found that the influence of the heat gain types and the heat intensity on the time constant the change rate was relatively small and the heat capacity of passive walls had a great influence,by analysis of the influencing factors on thermal dynamic characteristics of the radioactive cooling room.Determined heat capacity as a sensitive factor,which can be provide help for tube-embedded envelope radiation cooling system operation.