Analysis of the non-uniform thermal environment of local floor and ceiling radiant heating: Numerical simulation and thermal comfort experiment

Abstract

Local radiant heating is a crucial method for avoiding inefficient heating and reducing energy consumption in buildings. To supplement existing research, which primarily focuses on local vertical-wall radiant heating, this paper investigates the non-uniform thermal environment of local floor and ceiling radiant heating rooms under various radiant positions, areas, and temperatures. The study utilizes numerical analysis by Ansys Fluent and thermal comfort experiments in Xi'an, China, which has a Dwa Köppen climate classification. When the local heating zone is located near windows and doors, the radiant film preferentially exchanges heat with them, resulting in a decrease in air temperature and mean radiant temperature. In such cases, it is recommended to increase the radiant temperature or area. With a radiant area of 5 m2 and a radiant temperature of 25 °C, expanding the radiant area to 15 m2 increases the average air temperature in the local heating zone by 5.0 °C, while raising the radiant temperature to 29 °C increases it by 1.4 °C. Moreover, enlarging the radiant area can effectively improve occupants' skin temperature, thermal sensation, and overall thermal comfort. When the radiant area and temperature are determined, priority should be given to local floor radiant heating over local ceiling radiant heating due to its lower air temperature, larger temperature gradients, and smaller mean radiant temperatures. This study aims to provide references for proposing refined design and regulation parameters of local floor and ceiling radiant heating systems in the future.