embedded-tube radiant systems; TRNSYS models; finite difference method; experimental measurements
Radiant floor heating and cooling systems can be beneficial in various applications such as heating or cooling buildings and in infrastructure applications such as de-icing of bridges and roads as well as snow melting. Such systems usually include a significant amount of thermal mass, thus providing energy flexibility in buildings. Models of embedded-tube radiant systems are therefore useful to predict their behavior (rate of heat transfer and outlet heat-transfer fluid temperature), which can be used for the development of predictive control strategies and optimal control algorithms. As a result, a comparison of different models is conducted in this paper. The TRNSYS simulation software provides three different ways of modeling radiant floor systems (Type 56, Type 653, and Type 993), which are compared in this paper with one another in order to assess their accuracy and limitations. Each approach is compared with measurements from an experimental set-up in a controlled environmental chamber. This paper aims at: (i) evaluating the appropriate model resolution for embedded-tube radiant floor systems, (ii) validating experimentally the three aforementioned TRNSYS types (which have been validated qualitatively only), and (iii) providing a mathematical explanation of Type 993 (whose description is still unavailable to TRNSYS users). A sensitivity analysis is also performed to estimate the impact of the different types’ parameters.