| Popis: |
This communication introduces an experimental setup for investigating the effect of solar radiation on the reduction of transmission heat losses and the steady state thermal conductance of uninsulated and insulated multi-layer wall samples. The setup consists of two adjacent climatic chambers, which share a common wall, in which the multi-layer wall samples are mounted. A solar simulator is applied within the outdoor air climatic chamber, whose radiation spectrum and radiation intensity are approximately equivalent to those of the sun. The first tests have been carried out on a wall sample with a typical structure of existing buildings from the year 1930 in Germany. In addition, a high-performance insulating plaster layer has been applied on a basic test sample (with existing building structure) to replicate and assess the refurbished scenario. Furthermore, a numerical investigation on the transient heat transfer process is carried out by using the simulation software COMSOL Multiphysics®. The experimental results of both uninsulated and insulated wall samples are validated against 1D and 3D models. As seen, the uninsulated wall, whose thermal conductance was experimentally determined to be equal to 1.79 W/(m²K), absorbs a heat flux of 208 W/m² through its external wall surface over a period of 8 hours. A fraction of 9.8 % of the absorbed heat arrives as a gain on the internal wall and reduces the transmission heat losses by 11.7 % over a period of 55 hours. On the other hand, the thermal conductivity of the insulation layer of the refurbished wall sample with micro hollow glass spheres was estimated by a parameter estimation procedure using the 3D model and the obtained experimental data. Using the estimated thermal conductivity, a thermal conductance of 0.42 W/(m²K) has been obtained for the refurbished wall sample. |
