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Theoretical Evaluation of the Vapor Compression Cycle With a Liquid-Line/Suction-Line Heat Exchanger, Economizer, and Ejector.


pdf icon Theoretical Evaluation of the Vapor Compression Cycle With a Liquid-Line/Suction-Line Heat Exchanger, Economizer, and Ejector. (1983 K)
Domanski, P. A.

NISTIR 5606; 37 p. March 1995.

Available from:

National Technical Information Service
Order number: PB95-216917

Keywords:

air conditioning; ejector; liquid-line/suction-line heat exchange; Rankine cycle; refrigeration; vapor compression cycle

Abstract:

The report presents a theoretical analysis of three vapor compression cycles which are derived from the Rankine cycle by incorporating a liquid-line/suction-line heat exchanger, economizer, or ejector. These addendums to the basic cycle reduce throttling losses using different principles, and they require different mechanical hardware of different complexity and cost. The theoretical merits of the three modified cycles were evaluated in relation to the reversed Carnot and Rankine cycle. Thirty-eight fluids were included in the study using the Carnahan-Starling-DeSantis equation of state. In general, the benefit of these addendums increases with the amount of the throttling losses realized by the refrigerant in the Rankine cycle. The liquid-line/suction-line heat exchange cycle shows the smallest COP improvement. Theoretically, the ejector cycle can reach the highest COP, but this requires a high level of ejector efficiency, which has not been demonstrated to be feasible in practice. If the two-phase ejector efficiency is assigned the value attainable in a typical single-phase ejector, the COP of the ejector cycle is comparable to the COP of the one-stage economizer cycle.