Experimental and numerical study on the application of low-temperature radiant floor heating system with capillary tube: Thermal performance analysis

Abstract

This study is practice-based learning, investigated the thermal performance of the conventional Korea standard radiant floor heating system with polybutylene pipe (the Model with PB) and a low-temperature with capillary tube (the Model with CT) in an experimental test and simulation model, analyzing the thermal environment based on the floor surface temperature and indoor air temperature distribution. A new method that analyzes the thermal performance of two different floor heating systems being matched simultaneous measurement were developed and applied. Results of the simulation analysis were verified by comparison with the results that achieved through an analysis using the same conditions as the experimental test performance evaluation. The results show that the Model with CT maintains floor surface temperature more stable than the Model with PB under same hot water supply temperature condition. The standard deviation of floor surface temperature was only 0.5–0.6 °C for the Model with CT, showing that it had a very uniform distribution. The Model with PB had three times more initial response time toward intermittent operation compared to the Model with CT for the initial indoor air temperature to rise by 4 °C. The Model with CT showed a 12.1% and 9.2% increase in thermal performance at hot water supply temperatures of 55 °C and 40 °C, respectively, compared to the Model with PB. The thermal comfort (PMV, PPD) from the Model with CT at a hot water supply temperature of 40 °C is better than that of the Model with PB at a hot water supply temperature of 55 °C. Further research remains necessary to analyze long-term behavior and performance of this system. The differences and special features of this experimental study is that two different forms of floor heating systems were evaluated based on the same location of the equipment and the same heating load. A verified simulation model was then used to analyze the changes in heating effect while changing the depth of the embedded capillary tubes.