Water-source heat pump renewable energy utilization
WATER as a renewable energy source.
Hydrothermal energy can be briefly described as the heat stored in the water of lakes, rivers, ponds, and similar. Due to the high mass and thermal capacity of water, a huge amount of heat is available and the temperature of the water during the year can be considered constant.
The interesting thing is that this energy can be recovered and used dipping into the lake (for example) a heat exchanger where water or water-glycol mixture flows at a lower temperature than the water of the sink (cold energy source).
The heat of the earth’s mantel, a semi-fluid layer of rock at high temperatures, is transmitted by conduction through the rock of the Earth's crust.
The intensity of this energy flow depends on the distance of the mantel from the earth’s surface and generates a temperature gradient variable from 0.01°F/ft and 0.06 °F/ft.
Thanks to this phenomena it is possible to find some warm underground water even very close to the earth’s surface. The temperature of this water is constant through the year and it is not affected by the temperature of the atmosphere. It means that it provides an excellent heat source to be recovered by the heat pumps.
In conclusion, the hydrothermal energy can be fully exploited if the water sink is big enough, relatively easy to be tapped and permitted by local regulations.
Standard installations are open loop because the water is pumped in a heat exchanger where the heat pump recovers the renewable energy and then it is pumped back to the sink.
Similar to the ground source applications, during winter time the energy flows from the water to the heat pump and vice versa during summer time.
In addition, the performance of the system is not affected by the weather conditions and therefore the seasonal performance factor of the unit is normally higher if compared to an air source installation.
This is the reason why, unlike the Air Source Heat Pumps, the Water Source Heat Pumps (WSHP) can achieve high performances even if installed in very cold climate zones.
GAHP-W is the Robur Water Source Gas Absorption Heat Pump: Max outlet hot water temperature: 149°F, Minimum outlet cold water temperature 37.4°F, GUE: Over 139%