Field Measurement And Simulation Of Outdoor Space Radiation Environment In Cold Area

In the study of outdoor thermal environment,radiation is one of the most complex physical environmental parameters due to its instantaneous variability and spatial unevenness.Domestic and foreign scholars have carried out a lot of research on the actual measurement and simulation of outdoor radiation,but there are still some imperfections.In this paper,through theoretical analysis and experimental research combined with simulation approach,firstly,the general rule of the radiation in the outdoor space radiation field is explored.Secondly,the in-depth analysis and comparison between the six-direction method and globe thermometer method are conducted.Finally,the calculation and optimization of the outdoor thermal comfort model are carried out.In this paper,a multi-condition radiation observation experiment was conducted at selected test sites in the campus of Tianjin University,and the general rules of outdoor radiation changes were summarized.It is found that the composition of the space would have a significant impact on the short-wave radiation flux.The reduction of Sky View Factor(SVF)will result in the reduction of short-wave radiation level in the site,but it has no significant impact on the overall level of long-wave radiation.The solar altitude angle and azimuth angle change in different seasons,which mainly affects the short-wave radiation flux.The change of air temperature and underlying surface temperature caused by the alternations of seasons leads to the change of long-wave radiation.Changes in weather conditions have a significant effect on short-wave radiation,but little effect on long-wave radiation.Combining theoretical analysis and experimental data,it was found that the average results of the six-direction method and the globe thermometer method are well correlated,but the results of Tmrt(globe)within a single day are very volatile and the range is very large.As the short-wave radiation flux increases,the accuracy of the Tmrt(globe)result decreases.Different wind speeds have different effects on the results.When the wind speed is lower than 0.1m/s and higher than 1.5m/s,the inaccuracy of Tmrt(globe)results is high.Accordingly,the accuracy of the globe thermometer method is evaluated and its modification is proposed.In addition,the change of wind direction affects the heat distribution and heat transfer effect on the black sphere surface.Finally,the outdoor thermal comfort models are sorted out and the calculation methods of radiation heat transfer of different models are summarized.And the optimization of the radiation heat exchange module is explored,which provides a basis for the subsequent exploration of the relationship between fluctuations in radiation parameters and local thermal perception.