Abstract
The paper presents a simplified mathematical model to describe the transient heat transfer of a radiant floor heating system. A purpose-built test room has been realized to investigate the actual thermal response of a concrete radiant floor in unsteady-state conditions. Beyond the temperature sensors needed for the standard thermal analysis of the heat transfer inside the chamber, the floor temperature was retrieved by means of an infrared thermography camera, in order to validate more precisely the proposed analytical model. The infrared thermography analysis gives interesting information on the floor temperature distribution during the transient, highlighting the pipes’ layout and, if present, inhomogeneous floor zones. The thermal images have been elaborated in order to set and tune the colour map. A portion of the image has been defined for measuring the surface floor temperatures with a previous evaluation of the parameters dealing with the thermographic technique, in order to perform the quantitative survey. The comparison results show that the calculated air and floor temperatures substantially agree with the temperatures measured by infrared thermography and thermocouples, provided that the boundary conditions obtained by the field measurements are strictly reproduced in the lumped capacitance mathematical model. The difference between the two approaches results in values lower than 4 °C during the entire monitoring period: a satisfactory outcome, considering the approximations of the analytical method. The proposed model and its infrared thermography measurements validation represent a useful tool to understand at first sight the floor radiant panels behaviour in the start-up and switch off period, at the aim of gather useful information for the difficult task of their regulation.
Highlights
The use of radiant floors for heating and, less frequently, for cooling purposes, has been increasing in recent decades, both in residential and commercial buildings
The present study examines the transient heat transfer in a hydronic concrete radiant floor; the temperature field is analysed by means of an analytical model and experiments in a test room
This paper presents an analytical and an experimental method aimed at describing the transient behaviour of a concrete radiant floor, made of a concrete screed, a layer of insulation below water pipes, an ashlar panel and a wooden slab
Summary
The use of radiant floors for heating and, less frequently, for cooling purposes, has been increasing in recent decades, both in residential and commercial buildings. Ho et al [10] proposed a numerical method to predict the transient responses of a hydronic radiant floor They used both difference and finite element methods for performance comparison purposes, observing that the model transient resulted faster than the experimental one. The dynamic behaviour of a lightweight and concrete radiant floors were investigated by Zhao et al [11], examining the start-up phase with the introduction of the time constant to evaluate the floors thermal inertia They used a numerical method applied to a bi-dimensional domain, adding the analysis of the solar radiation impact on the dynamic performance. The present study examines the transient heat transfer in a hydronic concrete radiant floor; the temperature field is analysed by means of an analytical model and experiments in a test room. With the support of a quantitative thermographic procedure in a large and significant portion of the floor, the study aims at verifying the applicability (and the limits) of the lumped capacitance model as an easy tool to analyse the thermal transient behaviour of a complex system composed by multi-layers stratigraphy and internal heat generation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
