DETERMINATION OF CONVECTIVE, RADIATIVE, AND TOTAL HEAT TRANSFER CHARACTERISTICS OVER A RADIANT HEATED CEILING: A COMPUTATIONAL APPROACH

Özgen Açikgöz

doi:10.18186/thermal.623191

Abstract

also been given in international standards for experimental approaches. In accordance with the experimental standards, the analyses are realized at the room dimensions of (L x H x W= 4 x 3 x 4 m), and at the thermal boundary conditions of (Tc= 35 – 50oC), (Tw= 15 – 24oC), (Tf= 15 – 24oC). As a result of iterations conducted using a computational fluid dynamics package program code, each corresponding to a case study, convective, radiative, and total heat fluxes from radiant heated ceiling are obtained, and afterward using relevant reference temperature proposed in the literature, heat transfer coefficients pertaining to convection, radiation, and total heat transfer have been found. In conclusion, average heat flux values of 95.83 Wm-2 and 17.49 Wm-2 are gained through the examined radiant heated ceiling, by means of radiation and convection, respectively. This denotes that roughly 85% of total heat transfer from the ceiling arises through radiation that is very compatible with the relevant literature. Finally, spanning the entire different case studies, average convective, radiative, and total heat transfer coefficients of 1.1 Wm-2K-1, 5.4 Wm-2K-1, 7.6 Wm-2K-1 are acquired.

Highlights

On radiant heating and cooling applications, numerous studies exist in the relevant literature
Carrying out case studies in computational fluid dynamics programs such as one used in the present work ANSYS 14, provides researchers and engineers to do these investigations in broader thermal boundary conditions and different room dimensions
Between the outcomes of two studies presented in this figure, a slight deviation between the trendlines of studies are discerned. This may be attributed to unavoidable experimental errors in the corresponding study, numerical errors due to the method performed in the current examination, or thermal boundary conditions of surfaces other than the heated ceiling in the present investigation

Summary

INTRODUCTION

On radiant heating and cooling applications, numerous studies exist in the relevant literature. The point still at some extent, has necessitated further investigation is the convective phenomenon which determines the total heat transfer characteristics over a radiant heated/cooled surface To respond to this purpose, in the present study, the heat transfer characteristics pertaining to a radiant ceiling heating system are investigated in a numerically modeled room at the dimensions of LxHxW= 4x3x4 m, and at the thermal boundary conditions of (Tc= 35 – 50oC), (Tw= 15 – 24oC), (Tf= 15 – 24oC). Solving governing equations (continuity, momentum, and energy) requires a package program to be employed For this purpose, initially, the simulated office was drawn and meshed by means of the program DesignModeler within ANYSY 14, and thermal boundary conditions were input and necessary options such as the turbulence model to be used, was selected in the program FLUENT. Combinations of interval counts in x-y-and z axes 20x20x20 35x20x35 45x25x45 55x30x55

RESULTS AND DISCUSSION

Results of derived correlation

CONCLUSION