On the coupling of a zonal model with a BES model for predicting vertical temperature distribution

Abstract

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.The airflow in one zone is often treaded as ‘fully mixed’ in Building Energy Simulation programs (BES) e.g. TRNSYS. On the other hand Computational Fluid Dynamics (CFD) are too complex and time-consuming to predict temperature and relative humidity in a building for a longer time-period, such as one year. Nevertheless several building applications require a prediction of the vertical distribution of the indoor relative humidity and temperature. This paper presents the development and possibilities of a coupled TRNSYS-zonal model, which allows accounting the stratification in a room. The zonal model is based on the block-model proposed by Togari [1] and describes a one dimensional heat and mass transfer between horizontal layers. The goal of this preliminary study is to examine the effect of parameters such as the number of layers, the value of the heat convection coefficient and the choses time step. To validate the implemented TRNSYS-model, the case of natural convection in a test room (3m x 3m x2,55m) described by Arai [2] and Togari [1] has been used.