Abstract
Thermal output, surface temperatures, and supply and return water temperature were measured for a wall cooling system involving pipe attached to a wall section made of thermally insulating blocks. The experiment was performed for warm climatic conditions typical of, e.g., summer in Central and Northern Europe. The outdoor environment was simulated by a climatic chamber while the indoor climate was simulated by attaching a hotbox to the wall surface. The sensitivity of thermal output to several design parameters was investigated by 2D numerical simulations. The measurements showed a fast thermal response of the wall system. The cooling output was 38.3 W per m2 of the cooling area which equalled about 4.8 W/m2 per 1 K temperature difference between water and hotbox. The lowest surface temperature of 19.6 °C was measured at the pipe. Thus, the cooling output could be enhanced by reducing the surface temperature closer to the dew point temperature. The temperature of water in the pipe was very close to the surface temperature. It was illustrated how this characteristic of the wall cooling system tested positively affects the efficiency and cooling capacity of an air-to-water heat pump.
Highlights
One of the key global problems in the 21st century is climate change and the resulting weather instability and hotter summers
The corresponding supply water (Ts) and surface temperature (Tsurf,A–D) was 17.9 °C and 21 °C, respectively. This shows that the thermal output of the wall could be enhanced by further decreasing the wall surface temperature down to the dew point temperature
5.2 Results of parametric simulations The stationary simulations were performed for warm climatic conditions
Summary
One of the key global problems in the 21st century is climate change and the resulting weather instability and hotter summers. Promising technical solutions that could reduce the environmental impacts include the combination of the radiant system with a ground heat exchanger [5, 6], heat pump [7,8,9] or solar cooling system [10,11,12]. Wall cooling systems can be preferable to the more frequently used floors and ceilings. Wall systems can be more suitable for building retrofit because they do not reduce the story height and can be attached to existing structures. Radiant walls have a higher cooling capacity per surface area than floors (70 W/m2 as compared to 40 W m2) [3]. Wall cooling can lead to a more homogeneous distribution of room temperature and reduce the risk of thermal discomfort due to cold floors [15, 16]
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