Carnot COP Research Articles

New Ericcson type cryogenic cooler

A new regenerative cryogenic cooler of the Ericcson type, characterized by having a double acting piston, has been conceived. A schematic of the device is shown and the idealized cycle is presented, along with an elementary analysis. The performance of the ideal cycle is between 40–70% of the Carnot COP for a wide range of temperature ratios, with a regenerator void volume 40% of the expansion volume. Expressions for heat exchange processes of the idealised cycle are expressed in terms of dimensionless design parameters.

Design considerations for refrigeration cycles

The Carnot COP, which assumes a thermodynamically ideal cycle in which no irreversibilities exist, is often considered to be a design goal for actual cycles. However, the Carnot COP does not consider heat transfer mechanisms. Heat transfer at a finite rate is necessarily an irreversible process and unavoidable in a refrigeration cycle. The lack of consideration of rate processes reduces the usefulness of the Carnot COP as a realistic design goal. In this paper, the limitations of both thermodynamics and heat transfer are considered to identify a more realistic design goal for the COP of refrigeration cycles. The consideration of heat transfer limitations leads to a design rule for the optimum distribution of heat exchange area between the low- and high-temperature heat exchangers.