Abstract
In order to achieve the correct heat balance equations for the walls of an air-conditioned space, the simultaneous quartic equations are generally required to be set up due to existence of radiant heat exchange between the interior surfaces. However, strict solving of the set of simultaneous quartic equations does not seem to be quite easy. In this regard, linearization process is generally applied to convert the quartic equations into the linear ones and the resultant set of simultaneous linear equations can be finally solved by matrix method. However, finding of the coefficient matrix in the matrix method seems to be troublesome. On the other hand, if the error arising from the linearization in matrix method, exceeds the limitation, the iteration process has to be performed in order to proceed the solution. In this paper, iteration process is proposed as a method through which the accurate heat balance equations can be directly solved. This method, so far called MRT-iteration method by the authors, is supposed to contain few advantages comparing with the abovementioned matrix method. In other words, as the algorithm being applied in the procedure of computer programing is simple above all, an accurate solution without any error arising from the linearization process can be directly obtained. Also, in this method the surface temperatures can be considered as effective factors in determining the convective heat transfer coefficients in the vicinity of the walls. In addition, a solution with sufficient accuracy can be practically reached within few times of iterations in the calculation, and this helps curtail the computation cost. In this study, iteration method has been employed in solving the heat balance equations of the space for two cases, that is, when the space is heated seperately, by warm air heating system and or radiant heating system. Meanwhile, for either case two different conditions of operation are assumed; first, if the space temperature is regulated by means of room temperature control, and second, if the space temperature is regualted by means of operative temperature control. Moreover, although Gebhart absorption-factor method has been applied in the calculation of radiant heat exchange, computations of the absorption factors have been proceeded, not by means of matrix method, but through simple algorithm by using the iteration method.
