THERMAL SCIENCE

International Scientific Journal

Thermal Science - Online First

online first only

CFD-simulation of indoor climate in low energy buildings computational setup

ABSTRACT
In this paper computational fluid dynamics (CFD) was used for simulation of the indoor climate in a part of a low energy building. The focus of the work was on investigating the computational setup, such as grid size and boundary conditions in order to solve the indoor climate problems in an accurate way. Future work is to model a complete building, with reasonable calculation time and accuracy. A limited number of grid elements and knowledge of boundary settings are therefore essential. An accurate grid edge size of around 0.1 m was enough to predict the climate according to a grid independency study. Different turbulence models were compared with only small differences in the indoor air velocities and temperatures. The models show that radiation between building surfaces has a large impact on the temperature field inside the building, with the largest differences at the floor level. Simplifying the simulations by modelling the radiator as a surface in the outer wall of the room is appropriate for the calculations. The overall indoor climate is finally compared between three different cases for the outdoor air temperature. The results show a good indoor climate for a low energy building all around the year.
KEYWORDS
PAPER SUBMITTED: 2015-06-04
PAPER REVISED: 2015-10-15
PAPER ACCEPTED: 2015-10-15
PUBLISHED ONLINE: 2015-11-15
DOI REFERENCE: https://doi.org/10.2298/TSCI150604167R
REFERENCES
  1. Nielsen, P.V, Flow in Air-Conditioned Rooms. Ph. D. thesis, Technical University of Denmark, Copenhagen, 1974
  2. SCNH. FEBY12: Kravspecifikation för nollenergihus, passivhus och minienergihus - Bostäder (in Swedish) (2012)
  3. Rohdin, P., Molin, A., Moshfegh, B., Experiences from nine passive houses in Sweden - Indoor thermal environment and energy use, Building and Environment, 71, (2014), pp. 176-185
  4. Lin Z, Chow T, Wang Q, Fong KF, Chan LS. Validation of CFD Model for Research into Displacement Ventilation, Architectural Science Review 48:4 (2005) pp.305-316
  5. Allocca C, Chen Q, Glicksman L.R. Design analysis of single-sided natural ventilation, Energy and Buildings 35:8 (2003) pp.785-795
  6. Zhuang, R., Li, X., Tu, J., CFD study of the effects of furniture layout on indoor air quality under typical office ventilation schemes, BUILD SIMUL 7, (2014) pp. 263-275
  7. Zhai, Z. J., Zhang, Z., Zhang, W., & Chen, Q. Y.. Evaluation of various turbulence models in predicting airflow and turbulence in enclosed environments by CFD: Part 1—Summary of prevalent turbulence models. Hvac&R Research, 13(6), (2007) pp.853-870.
  8. Rohdin, P. Moshfegh, B. Numerical Predictions of Indoor Climate in Large Industrial Premises - A Comparison between Different k-ε Models Supported by Field Measurements. Building and Environment 42 (2007) pp.3872-3888.
  9. Wallentén P. Convective heat transfer coeffcients in a full-scale room with and without furniture, Building and Environment 36: (2001) pp.743-751
  10. Delaforce SR, Hitchin ER, Watson DMT. Convective Heat Transfer at Internal Surfaces. Building and Environment 28:2 (1993) pp.211-220
  11. Khalifa A-JN. Natural convective heat transfer coefficient - a review: II. Surfaces in two- and three-dimensional enclosures. Energy Conversion and Management 42: (2001) pp.505-517
  12. Boverket, BFS 2011:26, BBR 19 in English. Boverket (2011)
  13. Ansys. ANSYS CFX-14.5 Solver Theory Guide. Ansys,inc (2012)
  14. Chen Q, Xu W. A zero-equation turbulence model for indoor airflow simulation. Energy and Buildings 28: (1998) pp.137-144
  15. Stamou A, Katsiris I. Verification of a CFD model for indoor airflow and heat transfer, Building and Environment 41: (2006) pp.1171-1181
  16. Sørensen DN, Nielsen PV. Quality control of computational fluid dynamics in indoor environments. Indoor Air 13: (2003) pp.2-17
  17. Persson T. Elbesparing med pelletkaminer och solvärme i direktelvärmda småhus. Licentiate Dissertation, KTH Energiteknik, Stockholm, Sweden, 2004 (in Swedish)
  18. Celik IB, Ghia U, Roache PJ, Freitas CJ. Procedure for Estimation and Reporting of Uncertainty Due to Discretization in CFD Applications, 2008
  19. Roache PJ, Perspective: a method for uniform reporting of grid refinement studies. ASME J. Fluids Engng, 116: (1994) 405
  20. Howarth AT. The prediction of air temperature variations in naturally ventilated rooms with convective heating. BSER&T 6: (1985) 169
  21. Riederer, P., Thermal Room Modelling adapted to the test of HVAC control systems. Ph. D thesis, Ecole des Mines de Paris, France, 2002