Study On The Characteristics Of Non-uniform Thermal Environment And The Influence Of Background Radiation Field In Local Hot Air Heating

Comprehensive and continuous heating is the predominant mode of centralised heating in northern Chinese cities during the winter.According to the actual differential heat demand of personnel or space,detailed heating by time and space is a revolutionary method for conserving heating energy and providing thermal comfort for the human body.Local heating refers to a method of heating that is insufficient to maintain a specific temperature in local interior areas.Heat conduction type,convection type,radiation type,and convection radiation coupling type heating terminals are its primary forms.This article takes the local convection hot air heating terminal as its object of study,analyses the non-uniform distribution characteristics of indoor temperature created by such local terminals,and focuses on the impact mechanism of the background radiation field under varying wall temperatures of the room.The following research has been done on producing indoor non-uniform environmental characteristics after local convection heating,as well as the effect of background radiation fields on the environmental characteristics of the original convection field,in this paper through theoretical analysis,numerical simulation,and experimental testing:1)Establish non-uniform environmental characteristic parameters for indoor heating with local hot air.The local temperature imbalance rate is proposed in this document(φTlocal),heat source contribution(CDHS),and local air distribution characteristic index(P-ADPI)are utilized to conduct multidimensional evaluations of the temperature difference distribution characteristics of non-uniform environments,the heat diffusion characteristics of local heat sources,and the thermal comfort characteristics of indoor environments.And investigate the influence of various air supply methods,air supply parameters(temperature,velocity),and background radiation conditions(temperature,location)on the non-uniform characteristics of the interior environment.Comparatively,the underfloor air supply method achieves greater thermal comfort with fewer air supply parameters.2)Establish characterizing zones for non-uniform environment created by local convection heating.This paper proposes typical parameters.φTlocal is utilized to characterize the indoor temperature difference.This study,in conjunction with the statistical definition,provides the definition of the characteristic zoning of local heating that creates a non-uniform indoor environment:φTlocal>0.5 indicates the heating core,0.05<φTlocal<0.5 indicates the heating transition zone,and φTlocal<0.05 indicates the external heating dissipation zone.Through numerical simulation,the heat flow fields under different air supply modes,parameters,and background radiation conditions are obtained,and the spatial distribution and area changes of the characteristic zones are used to describe the indoor environment under different conditions.3)The impact of background radiation field on the non-uniform environmental characteristics of local convective heating.Using MATLAB to perform function fitting on the distinctive zoning boundaries of indoor non-uniform environments and to develop a mathematical model for the distinctive boundaries.To articulate the characteristic boundary function of the mixed side air supply system using a quadratic polynomial explicit function,it is necessary to introduce the parameter s.Due to the limited influence of background radiation conditions on the characteristics of interior non-uniform environments,background radiation is incorporated as a correction factor into the characterization boundary function in order to reduce errors.The correction coefficients of the background radiation temperature and location conditions on the boundary function of the characterized partition(without background radiation effects)are found to vary between 0.97 and 1.44 and 0.79 and 1.44,respectively.In conclusion,this study can provide a more thorough evaluation of the internal environmental characteristics produced by convective local heating.The characteristic boundary function can be used to calculate and predict the indoor characteristic zoning in order to meet the design requirements for the indoor environment created by local convection heating.