The Monte Carlo method and the region method are combined in this paper,where a high-rise building in Harbin were taken for example to investigate the infrared radiation field of building surface.The calculation model...The Monte Carlo method and the region method are combined in this paper,where a high-rise building in Harbin were taken for example to investigate the infrared radiation field of building surface.The calculation models of temperature field and radiation transfer coefficient on the exterior surface were established.Through the self-built Bidirectional Reflectance Distribution Function(BRDF)experimental device,the BRDFs of moorstone,aluminum plate,coated glass and Ethylene-Propylene-Diene Monomer(EPDM)on the surfaces under dry and wet conditions were measured at different incidence angles with respective laser wavelengths of0.6328μm and 1.34μm.For the two wavelengths,the reflection ratios of the material surfaces under dry and wet conditions were calculated respectively.Based on some proper simplifications of the background condition,the simulation analysis of the radiation field of building surface was carried out according to the wetness theory and the measured data.Taking the situation at 9:00 a.m.on the day of summer solstice as an example,this paper made relevant quantitative calculation for the solar radiation,the self radiation of the surface units,the radiating projection between the surface units,and the general infrared radiation of the building surface.Comparisons on infrared radiance field of the building surface were obtained under cloud-free sunshine conditions and rainfall conditions respectively,and the rationality of the results was discussed.展开更多
The current exploration focuses on the ethylene glycol(EG)based nanoliquid flow in a microchannel.The effectiveness of the internal heat source and linear radiation is reflected in the present investigation.The estima...The current exploration focuses on the ethylene glycol(EG)based nanoliquid flow in a microchannel.The effectiveness of the internal heat source and linear radiation is reflected in the present investigation.The estimation of suitable thermal conductivity model has affirmative impact on the convective heat transfer phenomenon.The examination is conceded with the nanoparticle aggregation demonstrated by the Maxwell-Bruggeman and Krieger-Dougherty models which tackle the formation of nanolayer.These models effectively describe the thermal conductivity and viscosity correspondingly.The dimensionless mathematical expressions are solved numerically by the Runge Kutta Fehlberg approach.A higher thermal field is attained for the Bruggeman model due to the formation of thermal bridge.A second law analysis is carried out to predict the sources of irreversibility associated with the thermal system.It is remarked that lesser entropy generation is obtained for the aggregation model.The entropy generation rate declines with the slip flow and the thermal heat flux.A notable enhancement in the Bejan number is attained by increasing the Biot number.It is established that the nanoparticle aggragation model exhibits a higher Bejan number in comparision with the usual flow model.展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.51276050)
文摘The Monte Carlo method and the region method are combined in this paper,where a high-rise building in Harbin were taken for example to investigate the infrared radiation field of building surface.The calculation models of temperature field and radiation transfer coefficient on the exterior surface were established.Through the self-built Bidirectional Reflectance Distribution Function(BRDF)experimental device,the BRDFs of moorstone,aluminum plate,coated glass and Ethylene-Propylene-Diene Monomer(EPDM)on the surfaces under dry and wet conditions were measured at different incidence angles with respective laser wavelengths of0.6328μm and 1.34μm.For the two wavelengths,the reflection ratios of the material surfaces under dry and wet conditions were calculated respectively.Based on some proper simplifications of the background condition,the simulation analysis of the radiation field of building surface was carried out according to the wetness theory and the measured data.Taking the situation at 9:00 a.m.on the day of summer solstice as an example,this paper made relevant quantitative calculation for the solar radiation,the self radiation of the surface units,the radiating projection between the surface units,and the general infrared radiation of the building surface.Comparisons on infrared radiance field of the building surface were obtained under cloud-free sunshine conditions and rainfall conditions respectively,and the rationality of the results was discussed.
文摘The current exploration focuses on the ethylene glycol(EG)based nanoliquid flow in a microchannel.The effectiveness of the internal heat source and linear radiation is reflected in the present investigation.The estimation of suitable thermal conductivity model has affirmative impact on the convective heat transfer phenomenon.The examination is conceded with the nanoparticle aggregation demonstrated by the Maxwell-Bruggeman and Krieger-Dougherty models which tackle the formation of nanolayer.These models effectively describe the thermal conductivity and viscosity correspondingly.The dimensionless mathematical expressions are solved numerically by the Runge Kutta Fehlberg approach.A higher thermal field is attained for the Bruggeman model due to the formation of thermal bridge.A second law analysis is carried out to predict the sources of irreversibility associated with the thermal system.It is remarked that lesser entropy generation is obtained for the aggregation model.The entropy generation rate declines with the slip flow and the thermal heat flux.A notable enhancement in the Bejan number is attained by increasing the Biot number.It is established that the nanoparticle aggragation model exhibits a higher Bejan number in comparision with the usual flow model.
