| The increasing living standard makes people’s requirements for indoor air environment increase.Ventilation mode has direct influence on indoor thermal environment and pollutant distribution characteristics in the air-conditioned room.Therefore,it is necessary to select a reasonable ventilation mode in the design of the air conditioning systems.The impinging jet ventilation system has been practically applied since the end of the last century.It also has the advantages of the mixing ventilation and the displacement ventilation.It can not only achieve similar energy-saving effects as the displacement ventilation,but also realize cooling and heating like the mixing ventilation.In theory,the impinging jet ventilation system is a more efficient and energy-saving air conditioning ventilation.However,it is rarely used in our country and lacks necessary research.In this paper,the numerical simulation method is used to compare the thermal environment and gaseous pollutant environment of the three ventilation modes(the mixing ventilation,the displacement ventilation and the impinging jet ventilation)in summer conditions.The results show that under the condition of the mixing ventilation,the indoor temperature uniformity is better.The temperature stratification is produced in the vertical direction of the impinging jet ventilation and the displacement ventilation room.The temperature in the upper part of the room is higher and the temperature in the lower space is lower.There is a certain temperature difference between the head and the ankle level for a person,but it is less than 3 degrees and meets the requirements of relevant specifications.the area near the air supply device and near the ground will cause very uncomfortable draft feeling.In addition,although the impinging jet ventilation room cause very uncomfortable draft feeling in the area,which is near the air supply device and close to the ground.Other locations can meet the thermal comfort requirements of the air-conditioned room.The order of the average carbon dioxide concentration in the personnel working area from high to low is the mixing ventilation,the impinging jet ventilation,and the displacement ventilation.The indoor air flow pattern has a direct influence on the indoor temperature distribution and the distribution of gaseous pollutants.While the position of the air supply device and the air supply temperature difference in the impinging jet ventilation room directly affect the indoor air flow pattern.Therefore,the influence of the position of the air supply device and the air supply temperature difference on the indoor thermal environment and the environment of gaseous pollutants in summer conditions are studied in detail.The results show that when the position of the air supply device is different,the order of the temperature difference between the head and the ankle level for a standing and sitting person from high to low is the radial jet,the jet near the x axis wall and the jet near the y axis wall.The air temperature difference has great influence on the indoor temperature distribution.When the air temperature difference is relatively small,there is no vertical temperature stratification in the impinging jet ventilation room.When the air temperature difference is large,there is obvious vertical temperature stratification in the room.In the room studied in this paper,the position of the air supply device and the air supply temperature difference have little influence on draft feeling.In the summer condition,different position of the air supply device has a great influence on the horizontal distribution of carbon dioxide concentration produced by people in the impinging jet ventilation room,and has little effect on the vertical distribution of the discharge efficiency.While the different air supply temperature has little effect on the distribution of carbon dioxide concentration produced by people in the room,and has a great influence on the vertical distribution of the discharge efficiency. |
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