| Radiant heating and cooling mode has high comfort and energy saving advantages, which has been widely used in recent years. In this paper, both the office building in HanDan and the villa in HangZhou adopt radiant heating and cooling system, building envelope thermal characteristics and thermal comfort of the rooms are analyzed theoretically and simulated under intermittent operation. The optimal control schemes under intermittent operation are developed. The main contents of this paper are following.1. Based on theoretical analysis of heat transfer mechanism of radiant air- conditioning system, the heat transfer calculation model is established. The thermal comfort index PMV of experimental test room 1(two external walls, towards the sun) is simulated by AIRPAK that is numerical simulation professional software. Experimental test room 1 adopts radiant floor cooling combined displacement ventilation system. Simulation results show that the PMV distribution in vertical direction and horizontal direction are in line with standards of human comfort.2. On the basis of the analysis of building intermittent air conditioning load characteristics, the software DeST was applied to calculate one by one hour load in whole year of the office building in Handan. Calculation results show that air-conditioning system runs three-quarters of the total time in the condition of 60% of full load, which illustrates feasibility and energy saving of the intermittent operation mode. By analyzing the thermal performance of different kinds of insulation, the conclusion that the thermal performance of inside insulation wall is better than the outside which is constituted by the same materials can be got only under intermittent operation mode.3. Through testing and analysis of radiant heating and cooling system under intermittent operation mode, the following concludes can be made: during the prechilling(preheating)period of two hours before opening the units and a period after closing them, the change range of indoor temperature is relatively great, changing approximately under exponential law. Whereas after preheating period or prechilling period, vertical temperature distribution and horizontal temperature distribution of the room are relatively uniform, thermal stratification are slight. Affected by building orientation and external envelope structure, temperature change range of temperature in shaded halves rooms is more than in exposed halves ones, and the rooms having two exterior walls are less than the three ones.4. VB software programming was applied to calculate the PMV and PPD value of each testing room. The following concludes can be made: in the cooling conditions, Room 2(only one external wall, towards the sun) has the best comfort, PMV=0.018, PPD=5.01%; Room 1(two external walls, towards the sun) PMV=0.47, PPD=10.88%; the indoor design temperature of room 3 (Only one external wall, in shaded halves) is less than requirement, PMV=-1.09, PPD=54.38%. In the heating conditions, the indoor temperature of room 5 (Audio-Visual Room is located in the first floor) is slightly high, PMV=0.83, PPD=30.57%; Room 4 (bedroom is located in the second floor) has better comfort, PMV=-0.21, PPD=5.96%.5. Based on the experiment analysis, the control strategy for the heating, cooling supply and transition season are separately analyzed. Take the office building and house building for example to explain the operation scheme for intermittent operation. In winter, radiant floor heating combined natural or forced ventilation can be used. In summer, radiant floor cooling combined displacement ventilation to dehumidify are adopted. In the transition season, fresh air handling unit combined natural ventilation is applied. |
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