Validation of a transient zonal model to predict the detailed indoor thermal environment: Case of electric radiators and wood stoves

Abstract

In building performance simulation (BPS), zonal models are intermediate models between standard models assuming perfectly-mixed room air and Computational Fluid Dynamics (CFD): they aim to predict the air temperature and velocity fields as well as the pollutant distribution inside a room using a computational time significantly lower than using CFD. The article aims at validating a transient zonal model that is currently implemented in the commercial BPS tool, IDA ICE. In theory, this onedimensional model can address a large variety of airflows and requires almost no a priori knowledge of the flow to be computed. The model is validated against measurements in a laboratory heated by either electric radiators or an electric stove designed to mimic surface temperatures of real stoves. Unlike radiators, the case of stoves has never been addressed in the literature and is challenging due to the strong thermal coupling between the room air and walls. Heat emitters have been placed either in the middle of the room or along walls. The zonal model remarkably well predicts the time evolution of the air temperature stratification in the room for all test cases. For a heat emitter in a central position, the wall surface temperatures are predicted correctly. Nevertheless, for a heat emitter along walls, these walls cannot be considered isothermal anymore, an assumption found in most BPS tools. The paper suggests that an automatized method to divide walls in the vicinity of heat emitters is necessary for a reliable prediction of the wall surface temperatures.

Parametric Energy Simulations of a Nordic Detached House Heated by a Wood Stove

“…The living room geometry has a L-shape and, in this new version, the stove geometry is directly integrated inside the virtual geometry of the room. The resulting geometry is therefore not convex and view factors between surfaces were computed numerically by IDA-ICE [10,11].…”

Fast prediction for indoor environment: Models assessment

“…Zonal models require division of an enclosed space into several sub-zones and assume the air characteristics in a certain zone are uniform. 9 Only a few nodes in a room are computed, which would significantly reduce computing demands. Commonly, zonal models would require several to dozens of seconds to finish a certain case and the use of empirical formulas to simulate airflow in a specific area.…”

Zonal model for predicting contaminant distribution in stratum ventilated rooms

“…Further, the two‐zone and multi‐zone models have been developed to improve the accuracy 32–38 . For the multi‐zone model, the generalized zoning method divides the room into several rectangular parallel‐piped subzones 39–41 .…”

“…The error can be reduced by applying special zoning methods 28,42 . For the special zoning method, the room can be partitioned according to the age of air, 43 thermal plume, 36 boundary wall, 41,44 contaminant source location, 16,33,35,37,38,45 etc. and shows better accuracy than the generalized zoning method.…”

“…35 Further, the two-zone and multi-zone models have been developed to improve the accuracy. [32][33][34][35][36][37][38] For the multi-zone model, the generalized zoning method divides the room into several rectangular parallel-piped subzones. [39][40][41] However, the contradiction between the well-mixed assumption and the realistic non-uniform air distribution results in large errors for the multi-zone model.…”