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I always wondered why we don't see more Sterling Engine based heat pumps. IIUC they can use almost any gas including air.
by tdeck 7d ago
I always wondered why we don't see more Sterling Engine based heat pumps. IIUC they can use almost any gas including air.
- formerly_proven 7d agoBecause they're sensible heat machines, instead of latent heat machines. In a perfect frictionless vacuum, both of these can achieve the same theoretical efficiency. In practice, not so much. In particular, the isothermal heat exchange of the ideal Stirling cycle requires heat exchangers with no thermal resistance (and therefore no temperature difference). A latent heat pump has a much easier time to very closely approximate isothermal heat exchange because condensation/evaporation temperatures at a given pressure are essentially constant.
- tdeck 7d agoWhat is the back of the envelope efficiency penalty we're talking about here?
- formerly_proven 7d agohttps://www.sciencedirect.com/science/article/abs/pii/S0140700723004826 https://www.sciencedirect.com/science/article/abs/pii/S01407... Looks like 30-50% less efficiency.
- tdeck 7d agoThank you!