Numerical Analysis of Convective Heat Transfer for Selected Geometric System

Abstract

The contemporary problems and issues of environmental protection refer to a large extent to problems related – generally speaking – with energy. Currently, the production processes mainly concern the combustion of energy fuels, transport – over long distances – by means of transport, their use for utility purposes, e.g. engine drive or heating. All these processes have a significant negative impact on the environment and are magnified by their enormous intensity and enormous size. While the processes of energy production and transport have been studied for many years, and their result are widely published, the issues related to the application and operation of heating devices are little known and require much observation and research. The operating indicators of heating devices are generally characterized by low values (natural convection) and their artificial increase (intensity) cannot be used due to the acoustic effects and additional (significant) investment costs. The article presents some results of research on the intensification of heat flow – i.e. the thermal efficiency of flat heaters placed in a room with a specific temperature. Physical phenomena were investigated numerically by shaping the heat exchange space. The tested systems concerned a room with a free-standing heater, a heater with a vertical panel mounted in parallel, and a system with a curved bottom plate forming the so-called de Laval nozzle. Interesting results of air velocity and temperature fields as well as values of the heat transfer coefficient along the height of the heater were obtained. Based on the presented research, it can be concluded that the creation of convection surfaces around the heater is advisable because it affects the intensity of heat exchange, which can be increased without energy-intensive energy expenditure, i.e. in a non-mechanical way. Undoubtedly contributes positively to investment and operating costs, which is so important in issues related to environmental protection.