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Modelling indoor air and hygrothermal wall interaction in building simulation: Comparison between CFD and a well-mixed zonal model

Steeman, H. J., Janssens, A., Carmelietc, J. and Paepe M.
2009
Building and Environment, 44(3): 572-583
CFD; Indoor climate; Heat and moisture transfer; Porous materials

Steeman, H. J., Janssens, A., Carmelietc, J. and Paepe M., (2009), "Modelling indoor air and hygrothermal wall interaction in building simulation: Comparison between CFD and a well-mixed zonal model", Building and Environment, 44(3): 572-583.
Abstract:
Traditional models for heat and moisture transport in buildings consider indoor air as a well-mixed gas with uniform properties. Computational fluid dynamics (CFD) offers the possibility of taking into account the effect of air distributions on the interaction with the walls. This paper compares simulations made with a traditional well-mixed model and a CFD model in search for the limitations of the well-mixed model. The possibility of improving the accuracy of the well-mixed results by using CFD generated surface transfer coefficients is investigated. To allow for a good comparison between both models the CFD model is extended with an effective penetration depth (EPD) model for the moisture buffering in the walls, an approach which is also used in the well-mixed model. The average indoor climate and the average relative humidity in the walls predicted by the CFD-EPD model and the well-mixed model with standard surface transfer coefficients agree quite well for the studied test case. The use of CFD generated surface transfer coefficients in the well-mixed model was able to improve the well-mixed results significantly in case a stable and physically relevant surface transfer coefficient could be related to the average indoor air conditions. The studied case showed that this is not always guaranteed.

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Author Information and Other Publications Notes
Steeman, H. J.
  1. CFD modelling of HAM transport in buildings: The importance of local indoor climate
  2. Coupled simulation of heat and moisture transport in air and porous materials for the assessment of moisture related damage
  3. Evaluation of the different definitions of the convective mass transfer coefficient for water evaporation into air
  4. On coupling 1D non-isothermal heat and mass transfer in porous materials with a multizone building energy simulation model
  5. On the applicability of the heat and mass transfer analogy in indoor air flows
  6. Sensitivity analysis of CFD coupled non-isothermal heat and moisture modelling  
Janssens, A.
Building Physics, Construction and Services http://aivwww.rug.ac.be/Onderzoeksbeleid/techno2002/EN/TW/I-TW01V02.htm
  1. Application of a new type of air and vapor retarder in a self-drying sloped roof with a cathedral ceiling
  2. Benchmark experiments for moisture transfer modelling in air and porous materials
  3. CFD modelling of HAM transport in buildings: The importance of local indoor climate
  4. Condensation risk assessment
  5. Coupled simulation of heat and moisture transport in air and porous materials for the assessment of moisture related damage
  6. Evaluation of the different definitions of the convective mass transfer coefficient for water evaporation into air
  7. Experimental validation and sensitivity analysis of a coupled BES-HAM model
  8. Heat and moisture response of vented and compact cathedral ceilings: a test house evaluation
  9. Impact of whole-building hygrothermal modelling on the assessment of indoor climate in a library building
  10. Inquiry on HAMCAT codes
  11. On coupling 1D non-isothermal heat and mass transfer in porous materials with a multizone building energy simulation model
  12. On the applicability of the heat and mass transfer analogy in indoor air flows
  13. Reliable control of interstitial condensation in lightweight roof systems, calculation and assessment methods
  14. Sensitivity analysis of CFD coupled non-isothermal heat and moisture modelling  
Carmelietc, J.
     


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