In 2013, Rudolph Draaisma, presented his ideas for the atmospheric heat pump (AHP), offering a vast improvement over commonly used heat pumps today.
Apart from a lower COP at moderate temperatures, the AHP beats the very expensive regular heat pump on all fronts. It is a cheap design and it uses no refrigerants, but plain air, or a nobel gas instead. The AHP performs independently from the temperature difference over the machine, while a regular heat pump stops performing when it becomes too large.
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