Primjena RC-modela u simulaciji dimamičkih procesa razmjene toplote građevinskih objekata sa okruženjem

Abstract

The applied methodology for the simulation of the dynamic heat exchange processes is based on the application of the RC-model (R-resistor, C-capacitor). According to that model the final number of parallel layers is formed through the cross- section of the construction element and to those layers the characteristics which are equivalent to the elements of the electric circuit are assigned. By establishing the heat balance equations for the nodes between adjacent layers, heat transfer matrices are determined for each time interval, and therefore the dynamics of heat exchange is defined as well. The complexity of the heat exchange process of the buildings with the environment is particularly pronounced in the cooling mode, when the influence of short-wave radiation is dominant within other influences. Due to the absorption of short-wave radiation, the processes of periodic accumulation and release of heat in the opaque building elements are expressed. The results of established model were compared on the results of three validation tests given in EN ISO 52017, and they showed good matches with the given hourly values of the operative temperature. After validation procedure, the effect of the thermal capacity influence on the dynamics of heat exchange of several different opaque building elements, the effect of the intensity of ventilation on the cooling needs as well as the influence of the external shade on the reduction of cooling needs were assayed.