INCREASING THE EFFICIENCY OF THE HEAT PUMP SYSTEMS BY A CONCRETE CORE ACTIVATION
Type of documentdoctoral thesis
Field of studyBuilding and Structural Engineering
Study programCivil Engineering
Institutions assigning rankCzech Technical University of Prague.
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Electrically driven heat pumps in combination with photovoltaic systems, as decentralized self-sustaining heat generation systems purely based on renewable energy, will experience a high priority and expansion degree in the near future. A heat pump is the more efficient the more is possible to reduce the temperature change between the heat source and evaporating temperature and the required flow temperature (condensation temperature). The innovation of this work consists in combining a tube spacing involving a temperature difference optimized concrete core concept (passive system) with an extremely responsive near-surface radiant heating system (active system pipe distance 50 mm), below the floor covering. It is essential and possible for the efficiency of the heat pump to provide adequate heating and cooling power for both above said systems at the same lowered flow temperature of about 25°C. This temperature reduction from 28°C to 25°C represents an additional gain of about 10% for the heat pump. In this case, the concrete core activation, which provides only about 50% of the power, is feasible to operate with a storage effect without any disadvantages. The responsive near-surface auxiliary heating system can provide the actual required additional power in accordance with the constant room temperature and without wasting energy, using highly accurate quantitative variable steady control of load. Furthermore, an optimized heat ground water pump and brine circulation is developed, furthermore built, and the increase of efficiency is proven by means of rigorous measurements. Using a special compressor construction, evaporator and condenser enables one to achieve the lowest temperature difference between evaporation and source outlet temperature and the approximation of condensation to flow temperature. By virtue of the practically feasible undercooling enthalpy and using an optimized electronic adaptive injection valve make it possible to increase the COP to 25% from industry-standard 5.6-6.0 to about 7.5 (in accordance with the standard EN 14511 at W 10/W 35; 10°C ground water, 35°C flow temperature). The developed low temperature in combination with the surface heat distribution system causes that the heat pump concept in operation at W 10/W 25 (flow temperature at 25°C) can reach a COP of nearly 10, without an auxiliary power unit. One kilowatt electric power results in 10 kilowatts of thermal heating energy, which is generated via the PV system without emissions and additional costs. Such a difference comes from the effect of environment of groundwater or from the power of the sun or the rain regenerative near-surface geothermal energy.
- Disertační práce - 11000 
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