Study On The Measurement And Model Of Thermal Comfort Of Subway Passengers In Beijing During Summer

The relative warmth index is concluded by ASHRAE through the thermal comfort experiment,which is used to determine the design parameters of the subway platform,the station hall and the air conditioning in the carriage.In the existing researches on evaluating the comfort of subway environment in China by using relative heat index,it is found that the evaluation result of relative warmth index is deviated from the actual thermal comfort of passengers,but the reasons for the difference between the two have not been deeply explored,and there is still a lack of research on revising this index.Therefore,it is of great significance to modify the relative warmth index and build a model that can accurately predict the thermal sensation of passengers,and further put forward the control method of air temperature in the station to meet the needs of passengers' health and realize the energy-saving operation of air conditioning.During the summer,Beijing metro line 1,line 8 and line 14 were selected as the test sites.During the test,the subjects conducted a series of riding process,respectively tested the thermal environment parameters in the station and investigated the thermal comfort of passengers at the test points.After the end of the test,it was found that the relative humidity of the air in the station was between 40%?80%,and the upper limit was beyond the range stipulated in the specification.The average air temperature in the ticket office of the subway station is 28?,the station hall is 27?,the platform is 26?,and the average air temperature in the train is 25?.The air temperature in platform and carriage of metro line 1 and line 8 during the peak period of passenger flow is higher than that in the stationary period,while the air temperature in the station of line 14 is the same as that in the stationary period.During the peak period of passenger flow,passengers are easy to feel uncomfortable.The thermal environment in the station during other periods can meet the thermal comfort needs of passengers.By comparing the thermal comfort of passengers on three lines,line 1 is the most uncomfortable,followed by line 14.When the air temperature in the station exceeds the regulated value,more than 50% of the passengers feel comfortable,which indicates that under the premise of satisfying the temporary thermal comfort of passengers,certain energysaving effect can be achieved by adjusting the air conditioning system.Uses the relative warmth index evaluation results of the Beijing subway passengers thermal sensation and the actual appear large deviation,the study found that the index with passengers,unlike in the standard,the relation between thermal sensation revised the index prediction accuracy than before correction have greatly increased,and put forward from the direction of the body's metabolic rate further correction relative warmth index.Based on the theory of multiple linear regression study passengers relationship with the factors affecting the thermal sensation,found that passengers area and the area before the air temperature,relative humidity and air velocity difference and the relationship between thermal sensation,and air temperature,relative humidity,air velocity and clothing thermal resistance and the metabolic rate were used as impact factor in building a model to predict thermal sensation,the model in passenger thermal sensation value plus or minus 0.3 thermal sensation scale within the scope of the prediction accuracy of about 60%.The above 8 factors were applied to the BP neural network of bayesian optimization to construct the passenger thermal sensation prediction model,which achieved a prediction accuracy of 76.1% and high reliability,and then proposed the air temperature regulation strategy in the subway station.