Providing thermal comfort and saving energy inside the buildings using a ceiling fan in heating systems

Abstract

In the present work, a numerical study was conducted to analyze the thermal comfort parameters and energy saving inside the room with specified dimensions using a ceiling fan with central heating systems during the winter. The flow was turbulent in all models and k-ε model was used to simulate turbulence. Rayleigh and Reynolds numbers were in the range of '1.15×' 〖'10' 〗^'11' '≤ Ra ≤ 1.55×' 〖'10' 〗^'11' and '6480 ≤ Re ≤ 19440' , respectively. The finite volume method (FVM) and SIMPLE algorithm were used to solve the governing equations. Based on the results, using the ceiling fan during the winter had a considerable effect on improving the thermal comfort and energy saving inside buildings. By using the ceiling fan, the effective room temperature increased by 0.35 oC that can be used to reduce the radiators temperature, thereby reducing energy consumption. Additionally, the study results indicated that the location of ceiling fan did not have any effect on room effective temperature and residents’ thermal comfort. Furthermore, based on the results, by turning the ceiling fan on and increasing the vertical velocity, the predicted mean vote (PMV) and the predicted percentage dissatisfied (PPD) indexes improved. However, after a certain velocity, the fan application changed to cooling, which was not appropriate for the heating system. The study results showed that PMV and PPD were only necessary conditions for providing thermal comfort. In this regard, in order to provide residents’ thermal comfort, each of the five factors composing thermal comfort indexes (PMV and PPD) should have been analyzed separately and place within its own permissible range (sufficient condition). Finally, the case CF.C with radiator temperature of 51°C, and fan normal air velocity of 0.20 m/s was the optimal model by providing the complete thermal comfort conditions and 37% energy consumption reduction.