Embedded water-based surface heating part 2: experimental validation

The transient operation of an embedded water-based floor heating system has been studied by means of a numerical simulation tool. Prior to this study, Caccavelli and Richard (Caccavelli D, Richard P (1994) Etude portant sur le dimensionnement d'un plancher chauffant a eau chaude en CIC. Rapport n(o) 2, n(o) GEC/DST-94.050R, CSTB, France.) experimentally derived reference data for the specific setup.

This article constitutes an attempt to experimentally validate the numerical simulation tool that was recently developed by Karlsson (Karlsson H (2010) Embedded water-based surface heating, part 1: hybrid 3D numerical model. Journal of Building Physics 33: 357-391). The thermal response of the system is tested in both long (16 h) and short (30 min) cycle experiments where the water flow alters between on and off.

Temperature distribution, within the floor construction, and the heat exchange process are studied throughout the test cycles. The model underestimates the steady-state heat exchange from the pipe loop by 16% when boundary conditions and thermal properties according to the reference case are applied.

Temperatures at the floor surface are assessed with good precision while temperatures at the core of the concrete slab are underestimated by up to 1.5 degrees C. Amplitudes, phase shifts, rise, and delay times at different measurement points are simulated with good precision. A sensitivity analysis is performed where material parameters and boundary conditions are analyzed.

None of the tested parameters can independently explain the observed general trend in temperature deviations between simulations and measurements.