Heat contracting with heat pump and eXergiemaschine
Two-stage heating solution with eXergiemaschine for efficient supply in apartment buildings
- Apartment buildings from the 1970s with 87 residential units in Lostau (Am Krankenhaus)
- 5 buildings with 4 heating centers
- Design per heating center:
- Air-to-water heat pump
- eXergiemaschine 40 kW
- 4 storage heaters, 800 liters each
- Fresh water stations
The company Enloc Construct in Dresden helps older apartment buildings to install new heating systems that are as CO2-free as possible - and this without additional costs for investors or tenants, because Enloc Construct offers heat on a contracting basis. In buildings from the 1970s, however, it is difficult to operate economically with just a conventional heat pump and flow temperatures of up to 60 degrees. The company therefore opted for a two-stage system for the apartment buildings in Lostau, in which the heating heat pump supplies heat at a low temperature level and the eXergiemaschine performs the temperature boost to 60 or 65 °C.
The two-stage solution pays off: instead of only receiving around twice the amount of heat per kilowatt hour of electricity on an annual average, a heat pump plus eXergiemaschine delivers almost twice the amount of heat for the same amount of electricity. The concept convinced Enloc Construct. „It is simply more economical because the Heating heat pump can thus run in the intended operating range and correspondingly efficiently and the eXergiemaschine the further temperature range with a COP of over five,“ says Managing Director Matti Hennel. „This results in the high annual system performance figures for the entire system.“
Image sources: Enloc Construct / Photographer: Paul Kuchel
Frequently asked, simply explained
From a physical point of view, energy is always conserved. However, it consists of usable parts, the exergy, and not directly usable parts, the so-called anergy.
Energy = exergy + anergy
In technical thermodynamics, exergy refers to the part of the energy that can perform work. In heating technology, exergy is the part that leads to heat flows due to the higher temperature level and thus makes space heating and domestic hot water heating possible in the first place.
Exergy, the proportion of energy that determines whether heat is usable, must be given greater focus. After all, exergy optimization is the key to system efficiency.
If the different temperature ranges of a well-stratified water storage tank are completely mixed, the water ends up with a uniform average temperature.
The energy content of the storage tank remains unchanged. During this process, the hot water transfers its heat to the colder water. This means that the exergy that existed at the higher temperature level compared to the average temperature and was required, for example, for
which would be necessary to heat drinking water, has disappeared, irretrievably, irreversibly. Exergy has become anergy. Anergy is energy that can no longer be used (without a new supply of energy). Only by using auxiliary means (e.g. electricity) can it be used again.
exergy arise.
In contrast to energy, exergy can therefore be reduced or even completely destroyed.
The varmeco fresh water technology uses instantaneous water heaters to heat domestic hot water only when required, eliminating the need to store it in a domestic hot water tank and inhibiting the growth of germs (e.g. legionella). The integrated VarCon211 controller only activates the charging pump when drinking water is required, which saves energy and ensures hygiene at the same time.
Thanks to the separation of heating and domestic hot water and adaptive control, the system adapts optimally to daily requirements. The circulation pump control keeps the domestic hot water at the right temperature and prevents the proliferation of legionella bacteria, ensuring a high level of hot water comfort and safety.
The eXergiemaschine recycles waste heat that escapes unused in many businesses and turns it into usable heat. It raises the temperature of the waste heat to a usable level and simultaneously cools the lower part of the heat storage tank, which improves the efficiency of the heat sources. This efficient use saves energy and is easy on both the wallet and the environment.
The eXergiemaschine is a special heat pump that enables high source temperatures and a wide temperature spread. This makes it an ideal partner for renewable energy systems, such as solar thermal and hybrid modules, which work more efficiently and supply more energy.
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