Computational Modeling of Conjugate Heat Transfer in a Closed Rectangular Domain Under the Conditions of Radiant Heat Supply to the Horizontal and Vertical Surfaces of Enclosure Structures

Abstract

536.33:536.244 We have carried out computational modeling of nonstationary conductive-convective heat transfer in a closed rectangular domain in a conjugate formulation with a local heat source (a gas infrared radiator). Four variants of possible description of the radiant energy distribution over the inner surfaces of enclosures have been considered. As a result of the computational modeling, differential (temperature fi elds and stream functions) and integral (Nusselt numbers) heat transfer characteristics have been obtained. It has been shown that the radiant fl ux distribution infl uences the heat transfer intensity.Introduction. The steadily increasing energy consumption, the problems with operating NPPs, and the limited capacities of renewable energy sources make the use of energy-saving technologies more and more topical. The traditional convective heating of large-size industrial premises is at present ineffective in many cases. The use of gas infrared radiators (GIR) can make it possible to reduce the energy consumption, according to the authors of [1], by more than 30% due to by local heat supply to the working places.Investigations of radiant heating systems are carried out mainly with the aim of choosing optimal characteristics of the GIR [2-4]. The obtained experimental data [5,6] have shown that a microclimate favorable for personnel is attained in using GIRs at lower expenditures of fuel resources. It is not always possible to perform natural experiments under the conditions of large-size production shops with locally sitting operating equipment. In this case, it is expedient to use methods of mathematical modeling in choosing the basic parameters of GIR-based heating systems and test subsequently the results of the theoretical analysis under production conditions. It has been found [7,8] that mathematical modeling of the processes of conductive-convective heat transfer in a conjugate formulation in solving analogous problems creates conditions for a much more detailed analysis of the temperature regimes of investigated objects of heat supply. Mathematical models based on the thermal balance of a room [9] do not completely take into account the spatial character of the heat transfer typical in practice. The known solutions of heat transfer problems during operation of radiant heating systems [10,11] ignore the convection. The mathematical model of conductiveconvective nonstationary heat transfer under radiant heating of one of the internal boundaries of a closed rectangular domain in a conjugate formulation [12] was formulated under the assumption that the heat fl ux is distributed uniformly only over the horizontal surface of the lower base. It is interesting to analyze the thermal regimes of heated objects under radiant heating with account for the possible distribution of energy released by the GIR over the surfaces of vertical enclosure structures.The aim of the present work is to model computationally the nonstationary process of radiant heating of a rectangular domain in a conjugate formu...

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