General Model of Radiative and Convective Heat Transfer in Buildings: Part I: Algebraic Model of Radiative Heat Transfer

Abstract

Radiative heat transfer is the most effective mechanism of energy transport inside buildings. One of the methods capable of computing the radiative heat transport is based on the system of algebraic equations. The algebraic method has been initially developed by mechanical engineers for a wide range of thermal engineering problems. The first part of the present serial paper describes the basic features of the algebraic model and illustrates its applicability in the field of building physics. The computations of radiative heat transfer both in building enclosures and also in open building envelopes are discussed and their differences explained. The present paper serves as a preparation stage for the development of a more general model evaluating heat losses of buildings. The general model comprises both the radiative and convective heat transfers and is presented in the second part of this serial contribution.Keywords: Radiative heat transfer, view factor, radiosity, room envelope, radiative heat in interiors, heat loss.

General Model of Radiative and Convective Heat Transfer in Buildings: Part Ii: Convective and Radiative Heat Losses

“…The present paper continues the previous contribution entitled General model of radiative and convective heat transfer in buildings: Part I: Algebraic model of radiative heat transfer [1]. The first part of the serial contribution explained the basics of the radiosity method for quantifying radiative heat transfer in buildings.…”

“…In the first part of the serial publication [1], the radiative transport of heat in enclosures has been thoroughly discussed and the computational radiosity method [10,[13][14][15] has been analysed. The method has been applied not only to closed systems of surfaces but also to open systems.…”

“…For further processing, it is important to realize which of the flows {φ i } is positive (heat emission from the surface into the room) and which of the flows {φ i } is negative (heat absorption from the room into the surface). According to the analysis presented in the first part of the serial communication [1], the positive flow is associated with the heated floor (warm surface) and the rest of the inner surfaces absorb energies (cold surfaces):…”

“…For this reason, the discussion should be aimed at the radiative and convective heat transfers. Since the radiative transfer was thoroughly discussed in the preceding contribution [1], the convective transport is the subject of the central interest.…”

Numerical study of heat losses of building walls containing reflective foils

“…The radiosity technique has been applied and extended by many other authors, among them, for example, Oppenheim, 26 Ecker and Drake, 27 Gebhart, 28 Sparrow, 29 Sparrow and Cess, 30 Wiebelt, 31 Love, 32 Gebhart, 33 Howell, 34 Clark and Korybalski 35 and Ficker. 36,37 Since the radiosity method has been recently discussed very thoroughly and illustrated by means of practical examples, only basic relations are recalled here without further details to avoid overlap with previous publications. 36,37 The radiosity method is actually a three-step numerical procedure.…”