INCREASING THE EFFICIENCY OF THE HEAT PUMP SYSTEMS BY A CONCRETE CORE ACTIVATION
Type of document
doctoral thesisdisertační práce
Author
Burger, Johann
Supervisor
Procházka, Petr
Field of study
Building and Structural EngineeringStudy program
Civil EngineeringInstitutions assigning rank
Czech Technical University of Prague.Metadata
Show full item recordAbstract
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.
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