Thermal performance of a radiant wall heating and cooling system with pipes attached to thermally insulating bricks

Abstract

A radiant wall heating and cooling system with pipes attached to thermally insulating bricks was tested using climate chambers and a hotbox. This system is especially suitable for building retrofit due to its affordability and ease of installation but can be also applied in new buildings. Besides walls, the design tested can be also used for ceilings. Thermal output and response, wall surface and cross-section temperature, and water temperature were measured under a range of thermal loads. The thermal response was fast despite the coupling of the pipe with the bricks; the time constant τ63 was 0.5 h. The low-conductivity core substantially reduced thermal losses meaning that the system can properly function even without thermal insulation. These qualities may present an advantage compared to systems with pipes coupled to a conductive core which require insulation and have longer response times. The difference between water and average surface temperature was small, up to 7.0 °C at the peak output of 100 W/m2, which benefits the energy source efficiency. However, the surface temperature was non-uniform, which should be considered to prevent local condensation. Numerical simulations at room level showed that locating the system at one wall leads to a non-homogeneous thermal environment. Installation at multiple walls can be preferable to attain more uniform conditions.