The Transient Conjugate Heat Transfer Analysis in Multi-zone of an Apartment House by using Crank-Nicolson Finite Difference Method (FDM)

Abstract

Purpose: This study was conducted for the purpose of accurate energy analysis of apartment house which is composed of multi-zones such as a bedrooms, a livingroom, and a kitchen. Those of multi-zonal spaces have different indoor thermal environment requirements depending on space usage. For the analysis of this study was selected the 74 ㎡ type unit, which has the largest amount of supply in residential needs. The orientation of the apartment house unit was divided into the southeast and southwest directions, and the annual heating energy demand was calculated and compared. Method: A multi-zone heat transfer is done in dynamic and a very complex, such as conduction, convection, radiation and the solar radiation in a various building elements. In this paper, the Crank-Nicolson FDM scheme and the ISO 13790 algorithm were employed to analyze a complex and transient heat transfer in the multi-zone of apartment house. Result: The results of the analysis are as follows; the total amount of annual energy requirement for the apartment house unit which oriented in the southwest is 756 ㎾h. and equivalent to 10.2 ㎾h /㎡. When the required amount of primary energy was converted equivalent to electricity by unit floor area, it was 28.1 ㎾h /㎡. On the other hand, the total amount of annual energy requirement for a unit oriented in the southeast direction is 1,037 ㎾h and 14.0 ㎾h /㎡. The result of conversion (electricity) to primary energy is 38.5 ㎾h /㎡. This result indicates that the energy demand is about 27% higher than the southwest.