| Natural ventilation of door or window may have great impacts on the thermal comfort and energy consumption of air-conditioning rooms;especially for the radiant air-conditioning rooms in summer hot and humid regions,natural ventilation of door or window may also increase condensation risk.The air carrying energy radiant air-conditioning system(ACERS)is researched in this study,which is a n innovative terminal form of radiant air-conditioning system.An experiment is carried out in an apartment installed with ACERS concerning three summer operation conditions,namely steady condition(without opening door and window),open-door condition,and open-window condition.Based on the measurement results of the maximum cooling load time as the boundary and validation conditions,three corresponding computational fluid dynamics(CFD)models are established to investigate the thermal performance of ACERS in terms of temperature and humidity distribution,airflow filed,and condensation risk.The thermodynamic method is applied to analyze the dynamic synergistic operation process of the air-conditioning room with open door/window.A synergistic operation model of mixing ventilation described by the temperature synergistic formula,moisture synergistic formula,predicted mean vote(PMV)synergistic formula,and energy consumption synergistic formula is proposed.Based on the experimental measurements and meteorological parameters,the sensitivity analysis of the mixing ventilation operation parameters on the indoor environment parameters is researched;and the synergetic effect of the supply air rate and door/window opening degree on the indoor PMV and energy consumption is analyzed.Considering the optimization of indoor thermal comfort and energy consumption,the synergistic evaluation index of mixing ventilation is presented to provide suggestions for the operation management of mixing ventilation parameters.It is indicated that under the steady condition in the test room with ACERS,the vertical temperature gradient between human head level and ankle height is about 0.1 oC and the air velocity in the occupied zone is about 0.1 m/s;there is a boundary zone with low condensation risk under the radiant orifice plate for about 12 cm.While in the unsteady conditions,the vertical temperature gradient between human head and ankle height is less than 0.6 oC and the air velocity in the occupied zone is about 0.1 m/s;the boundary zone to prevent condensation under the radiant orifice plate is approximately 6-8 cm.When the air-conditioning system and open door/window are operated according to the recommendations,the energy consumption can be reduced with an equally comfortable thermal environment.Under the calculating conditions of ACERS,the air supply of the air conditioner should be set as low grade when the window opening is between 10-40°;the air supply of the air conditioner should be set as middle grade when the window opening is between 40-60° or the door opening is between 10-20°;the air supply of the air conditioner should be set as high grade when the window opening is between 60-90° or the door opening is between 20-30°;and it would have obvious thermal discomfort when the door opening is above 30°.The ACERS has a high operation performance with low vertical temperature gradient,low air velocity,low energy consumption,and low condensation risk under both steady condition and unsteady conditions.It can be a promising technology to solve the summer air-conditioning problem of residential buildings in hot and humid regions.This study investigates the synergistic operation of natural ventilation induced by open door/window and mechanical ventilation induced by air-conditioning system in terms of basic conception,thermodynamic model,and model application.It provides guidance for the operation control and management of air-conditioning system and open door/window,and it also offers a new method for study on the mixing ventilation of buildings. |
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