| In the industrial production,the working environment temperature of some special jobs is as high as 40 ? due to the production conditions and process requirements,which will has serious impact on the thermal comfort of workers.In order to improve the working environment of the high temperature workshop,and improve the thermal comfort of the workers,the workshop should be set up local air supply device.But because of its own limitations,the traditional local air supply cann't well meet the demand of workers.In recent years,the personalized ventilation draws more people's attention because of its characteristics.Personalized ventilation can be improve effectively thermal comfort of workers by transport the cool air to the workspace directly.But the study of personalized ventilation is more about civil construction environment(such as office environment,etc.),and less about high temperature environment.To improve the thermal comfort of people working under high temperature,for the air supply method with the air supply hat(ASH)in a portable air conditioning system,the paper analyses the supply air performance of which by CFD numerical simulation technology.Which can be provide theoretical guidance to the development of the equipment in the future.In the paper,the main research work is as follows:(1)Firstly,confirms research thinking and technical route by analyze and summarizes the related research literature about the personalized ventilation.Second,the heat transfer model of head is established based on Pennes biological heat transfer equation,which solved the inadaptability to conventional thermal boundary conditions by analyze the human body heat dissipation characteristics,thermal regulation model and conventional wall thermal boundary condition.Finally,Conclusion the prediction method of the human body thermal comfort for non-uniform thermal environment and the evaluation index which can be apply to evaluate thermal comfort of head in the topic is established based on the local thermal sensation evaluation model of Zhang.(2)Under the ambient temperature of 40?,analyze the distribution of head skin temperature with people were to wear and not wear ASH by transient calculation.The results show that when wear ASH the average and highest temperature of head will be low about 1~2 ?compared with not wearing ASH at same time,and the rise rate of skin temperature is decreased obviously.Analysis the velocity and temperature distribution around the head known that the supply air can be formed a air curtain around the head which could cut off the invasion of high temperature ambient,and could isolates the head and the surrounding environment.(3)With the width of air supply outlet B is 10 mm and the space between the air supply outlet and head D is mm,the influence of supply air parameters on the thermal comfort of head is studied through simulation.Results showed that the value of ? will be rise and then decreased with the supply air temperature increase,and the optimal supply air temperature range appeared;The value of ? increases gradually along with the increase of supply air velocity,and decreases gradually along with the increase of supply air angle.But the supply Angle changed in the range of 0~15 ° almost no impact on ?,and the effects is different on different working conditions when the supply angle is greater than 15°.Based on analysis of calculation results can be obtain the reasonabe range of supply air parameters: temperature T is 24~28 ?,velocity V is 0.6~0.8 m/s,angle ? is 5~10 °.(4)Based on the calculation results of supply air parameters,analyse the influence of structural parameters of air supply outlet on the thermal comfort of head by simulation.And the reasonable structural parameters can be known from the results of analysis: the width of air supply outlet B is 10~15 mm and the space between the air supply outlet and head D is 10~15 mm. |
PDF Full Text Request