Abstract
The main goal of this investigation was to increase the solar fraction and reduce the demand for non-renewable primary energy in a building heating system. Thermal performance of the prototype evacuated tube solar collector/storage integrated with a PCM (ETC/PCM) was analyzed. Technical grade paraffin with onset melting point of 51.24°C was used as a PCM. It has been shown that the highest solar energy fraction in the building heating system was obtained with a thermal load of 40 W·m-2 and the highest the surface area of ETC/PCM aperture in relation to the heating surface area value of 0.2. Lowering the heating system parameters from 45/35°C to 35/25°C allowed for an increase in heat output from solar energy in the range from 2.71% to 5.44%. The largest increase in the solar fraction was in the range of the ratio of the surface area of the solar collector ETC/PCM aperture to the area of the heated building from 0.03 to 0.07. In summary, obtained results indicated that the proposed solution allowed reduction of non-renewable primary energy demand in conceptual heating system from 6% to 27% depending on the heat load of the building and the aperture area of the ETC/PCM.
Highlights
Increasing the share of renewable energy sources in the energy demand of buildings is possible, among others by storing energy
The proposed concept of combining a heat storage system in the ground and a storage tank with phase-changing material has contributed to the increase in the thermal efficiency coefficient COP of the heat pump compared to the ground storage system without phase change material and without solar collectors
The heat generated during the maximum solar irradiance can be used during low or no solar radiation
Summary
Increasing the share of renewable energy sources in the energy demand of buildings is possible, among others by storing energy. Among the phase-changing materials, many of the beneficial thermal and physicochemical properties have paraffins that do not have: corrosive activity, supercooling effect (occurs in a small, negligible degree) and phase segregation They are not toxic and flammable at low temperatures. The presented work presents the effect of increasing the use of solar radiation energy and reducing the building's demand for non-renewable primary energy by using the integration of an evacuated tube solar collector with paraffin as a heat storage material
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