Comparison of indoor air temperatures of different under-floor heating pipe layouts

In this paper, the indoor climate using five kinds of under-floor heating pipe layouts (i.e., uniformly laid under-floor heating pipes at center spacing 300 mm, 400 mm and 500 mm, respectively; non-uniformly laid under-floor heating pipes in one loop and two loops) were predicted by k–ε renormalization group (RNG) and discrete ordinates radiation (DO) simulation. Computational fluid dynamics (CFD) simulations and variance analysis were used to investigate the differences of vertical air temperature gradients and thermal homogeneity over the floor.The general conclusions from this study are that, among five kinds of under-floor heating pipe layouts, the indoor air temperature field above the floor 0.1 m can be considered as homogeneous, and the maximum temperature difference is no more than 1 °C. However, it is found that an abrupt temperature rise can be observed over the floor zones near the heating pipes. The current results of the investigation is validated by recent literatures presented by Hasan (2009) [8] and Catalina (2009) [18]. In comparison with five kinds of under-floor heating pipe layouts (at supply water temperature 50 °C and return water temperature 40 °C), it is recommended that the best layout method is the under-floor heating pipe uniformly laid at 400 mm center spacing, which meets the standard requirements such as NEN-EN-ISO 7730, ASHRAE 55-2004 and GB 50019-2003.