Heat transfer through window constructions

Abstract

Based on the results of theoretical, computational and experimental studies, the influence of the design features of glass unit (the number of chambers in a glass unit, the thickness of the glass, the ratio of the width of the glass unit to its height, etc.) on the intensity of convection and radiation heat transfer through translucent structures was determined. The dependence on the thickness of the gas layer of the structure of the free convection flow between the inner and outer glass of a single-chamber double-glazed window was determined. The dependence of the thermal insulation characteristics of windows on the physical properties of the gaseous medium (density, thermal conductivity, viscosity) located in the interlayer between the glasses was studied. The dependence of the intensity of radiation-convection heat transfer through translucent structures on the characteristics of the low-emission coating on the inner surfaces of the translucent part of the window was found. It has been shown that a glass unit without a low-emission coatings transfer most of the heat by radiation. Therefore, this low-e coating significantly increases the heat transfer resistance of windows. A thermophysical calculation model was developed to determine the effect of solar radiation on the thermal regime of translucent structures. Using it, the volumes of heat entering the room with solar radiation through translucent structures in the winter season were determined. The influence of heat fluxes from the ends on the temperature state of the adjacent window structures and walls was determined. The dependence of the operational characteristics and energy efficiency of the enclosing structure on the location of the translucent structure in relation to the window opening was established. The effect of the window frame profile configuration on the resistance of a translucent structure has been studied. The value of the heat transfer resistance of various window structures in the real conditions of their operation was experimentally determined. Experimental and numerical studies of heat transfer processes through energy-active windows, namely supply air’ ventilated and heated windows, have been carried out. Energy-active windows can be used as a backup heating system for the premises of the building, as well as to create a comfortable temperature and humidity regime in the room. Based on the results of theoretical and experimental research, recommendations were formulated regarding the main methods of increasing the energy efficiency of translucent enclosing structures and the walls adjacent to them.