Conference article

In conventional collector systems for the supply of domestic hot water and space heating the collectors come to a standstill during summer whenever the maximum temperature in the storage tank is reached. The resulting excess heat can be harnessed by a combined heat pump-Organic Rankine Cycle-system. The aim of this work is to simulate such a system in order to determine the optimum operating conditions and impacts on power requirement and cost. For this purpose models for collector; storage tank; heat pump and geothermal heat exchanger are implemented. First results indicate that the isentropic efficiency of the scroll expander has the largest influence on the ORC-revenue. For a system consisting of 12 m² flat-plate collector area with an expansion efficiency of ?_{s; exp} 0.7 = the power requirement for space heating and domestic hot water is reduced by 3.6%; whereas the costs decrease by 42 € or 12.3% respectively compared to a conventional system. The results suggest that an installation is more reasonable in larger dwelling units like hotels; senior citizens’ homes and multiple family dwellings.

Solar Heating; Organic Rankine Cycle; Heat pump