Study On Comfortable Air Velocity And Evaluation Method For Sleeping Human In Hot-humid Environment

With the growth of economic level,people’s demand for better indoor environment has gradually increased,and the energy consumption brought by the improvement of indoor environment has also increased rapidly.The fan improves the indoor environment by creating airflow and increasing the airflow velocity around the human body.It is widely used due to its advantages of low price,ease of use,and low power consuption.In summer,most residents in China are used to using fans to improve the indoor environment when sleeping.Since the physiological parameters of the human body in the sleep are different from those in the awake,and people cannot consciously change the thermal environment.It is not reasonable to directly copy the thermal comfort theory derived from the awake state to the sleep state,but the application research of the fan in the sleep state is less,and the use of the fan in the sleep state lacks scientific basis.In this paper,for the purpose of this article,through the thermal comfort human experiment,the thermal comfort evaluation prediction model is established to explore the appropriate airflow velocity under different temperatures and humidity in sleep state,and the fan’s summer use strategy is proposed.First of all,the reclining phase is an important transitional phase from the awake state to the sleeping state,so the thermal comfort of the human body in the reclining state is studied.In the artificial climate chamber,the experiment was carried out by using the floor fan.Three ambient temperatures of 28 ℃,30 ℃,32 ℃ and two relative humidity of 50% and 80% were selected,and the experiment was conducted under 6working conditions in total.20 healthy subjects participated in the experiment.During the experiment,the human physiological parameters and environmental parameters were continuously measured.The subjects filled out the experimental questionnaire according to the experimental requirements.The study found that the use of air blowing can improve the satisfaction of the subjects inthe hot and humid environment,reduce sweating and lower the average skin temperature.The evaluation model of draught satisfaction is obtained by establishing the relationship betweendraught satisfaction,air velocity and temperature in a hot environment.Based on the above result it is possible to determine the summer omfort zone for draught in reclining state..According to the human body heat balance theory,the experimental air velocity in the sleep state is obtained by calculating the comfortable air velocity in the reclining state.According to the investigation of fan using behavior in the state of recliningstate,four acceptable working condition were selected for night-time sleep experiment.During the experiment,the subject’s skin temperature was tested all night,and the subject’s subjective thermal comfort and sleep quality evaluation were obtained by questionnaires.The bracelet was used to monitor sleep quality at the same time.By comparing subjective evaluation of sleep quality with the objective one monitored by bracelet it is found that the subjective evaluation reflect the actual sleep quality of the human body better.Subjects under the conditions of 28℃-80% and 30℃-50% have better subjective response to sleep quality and thermal comfort evaluation,followed by 30℃-80%,but at32℃-50%,the sleep quality and thermal comfort evaluation are both poor,and it is not suitable to create a indoor thermal environment with a fan under this working condition.Finally,based on the characteristics of the heat exchange between the human body and the environment in the sleep state,a prediction model of the human body’s thermal comfort in the sleep state is established.The heat exchange between the human body and the environment is divided into three parts to calculate separately,and the thermal comfort model of the human body in the summer sleep state is obtained.Compared with the experimental data,the prediction result of this model is more accurate.Based on the above result,the comfortable air velocity in different environments in summer human sleep state is calculated.On the basis of considering the thermal adaptation of human body,the strategy for using air conditioning fan under different environmental conditions is proposed.The improvement of indoor thermal environment by fans was discussed,which provided a reference for improving indoor thermal environment by using fans under the hot environment in the Yangtze River Basin.