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Johnson Controls delivered a large heat pump system with Vahterus heat exchangers to boost a district heating system that formerly extracted heat from fresh lava on a volcanic island Vestmannaeyjar (Westmen islands) near the southern coast of Iceland. The lava temperature has been reduced over the last few decades and the volcanic heat could not been utilised anymore.

As the electricity supply is limited on the island, the local energy company HS Veitur hf begun searching for alternative energy sources to improve the situation. Their initial idea was to optimize the energy consumption of the water heating process. The solution they chose was a large 10 MW Heat Pump system built by Sabroe factory in Denmark with Vahterus heat exchangers.

The new setup can be expected to provide over 40 GWh/year of free ocean heat releasing that same amount of electricity for other more valuable activities in the island. The usage of heat pumps requires around 75% less energy than the former boiler whic is a significant improvement for both ecological and economical point of view.

The heating system is circular (closed loop): hot water is delivered to the homes and companies, and after use it gets pumped back to the boiling station for reheating. The system is built with 4 identical heat pump units, each with 2,5 MW heating capacity, designed as a flooded NH3 economised system. In the heat pumps, water is heated from 34°C to 77°C.

To achieve the highest possible efficiency, the heated circuit first enters the subcooler and condenser. After this, the flow is divided in to three: to one de-superheater and two oil coolers in parallel. The design of the system allows HS Veitur to achieve temperatures approximately 8-9°C higher than the condensing temperature, resulting in a superior COP.

With the constant challenge for finding more ecological alternatives in the energy market, the large Heat Pump application packages will likely face a growing demand around the world in the future.