Evaluation of thermal comfort using combined CFD and experimentation study in a test room equipped with a cooling ceiling

Abstract This paper reports a full-scale experimental campaign and a computational fluid dynamics (CFD) study of a radiant cooling ceiling installed in a test room, under controlled conditions. This research aims to use the results obtained from the two studies to analyze the indoor thermal comfort using the predicted mean vote (PMV). During the whole experimental tests the indoor humidity was kept at a level where the condensation risk was minimized and no condensation was detected on the chilled surface of the ceiling. Detailed experimental measurements on the air temperature distribution, surface temperature and globe temperature were realized for different cases where the cooling ceiling temperature varied from 16.9 to 18.9 °C. The boundary conditions necessary for the CFD study were obtained from the experimental data measurements. The results of the simulations were first validated with the data from the experiments and then the air velocity fields were investigated. It was found that in the ankle/feet zone the air velocity could pass 0.2 m/s but for the rest of the zones it took values less than 0.1 m/s. The obtained experimental results for different chilled ceiling temperatures showed that with a cooling ceiling the vertical temperature gradient is less than 1 °C/m, which corresponds to the standard recommendations. A comparison between globe temperature and the indoor air temperature showed a maximum difference of 0.8 °C being noticed. This paper also presents the radiosity method that was used to calculate the mean radiant temperature for different positions along different axes. The method was based on the calculation of the view factors and on the surface temperatures obtained from the experiments. PMV plots showed that the thermal comfort is achieved and is uniformly distributed within the test room.

[1]  Patrick Depecker,et al.  Eléments de comparaison du calcul des échanges radiatifs au sein d'un local chauffé par un radiateur , 1991 .

[2]  P. Fanger.  Moderate Thermal Environments Determination of the PMV and PPD Indices and Specification of the Conditions for Thermal Comfort , 1984 .

[3]  Ken-ichi Abe,et al.  A new turbulence model for predicting fluid flow and heat transfer in separating and reattaching flows—I. Flow field calculations , 1995 .

[4]  Toshiaki Omori,et al.  Thermal comfort and energy consumption of the radiant ceiling panel system.: Comparison with the conventional all-air system , 1999 .

[5]  Dennis L. Loveday,et al.  Thermal comfort in chilled ceiling and displacement ventilation environments: vertical radiant temperature asymmetry effects , 1998 .

[6]  Standard Ashrae.  Thermal Environmental Conditions for Human Occupancy , 1992 .

[7]  Frédéric Kuznik,et al.  Experimental and numerical study of a full scale ventilated enclosure : Comparison of four two equations closure turbulence models , 2007 .

[8]  Katsunori Nagano,et al.  Experiments on thermal environmental design of ceiling radiant cooling for supine human subjects , 2004 .

[9]  Frédéric Kuznik,et al.  A second order turbulence model for the prediction of air movement and heat transfer in a ventilated room , 2008 .

[10]  Wataru Urabe,et al.  Simplified human body model for evaluating thermal radiant environment in a radiant cooled space , 2001 .

[11]  Qingyan Chen,et al.  A Procedure for Verification, Validation, and Reporting of Indoor Environment CFD Analyses , 2002 .

[12]  Bahram Moshfegh,et al.  Numerical predictions of indoor climate in large industrial premises. A comparison between different k–ε models supported by field measurements , 2007 .

[13]  S. Tanabe,et al.  Comfort limits for asymmetric thermal radiation , 1985 .

[14]  Sture Holmberg,et al.  Flow patterns and thermal comfort in a room with panel, floor and wall heating , 2008 .

[15]  Jianlei Niu,et al.  ENERGY SAVING POSSIBILITIES WITH COOLED-CEILING SYSTEMS , 1995 .

[16]  Corina Stetiu,et al.  Energy and peak power savings potential of radiant cooling systems in US commercial buildings , 1999 .

[17]  Koichi Kitagawa,et al.  Effect of humidity and small air movement on thermal comfort under a radiant cooling ceiling by subjective experiments , 1999 .

[18]  Anastasios I. Stamou,et al.  Evaluation of thermal comfort in galatsi arena of the olympics ?Athens 2004? using a CFD model , 2008 .

[19]  Håkan Nilsson,et al.  Thermal comfort evaluation with virtual manikin methods , 2007 .