Theoretical Evaluation of the Vapor Compression Cycle With a Liquid-Line/Suction-Line Heat Exchanger, Economizer, and Ejector.
Theoretical Evaluation of the Vapor Compression Cycle
With a Liquid-Line/Suction-Line Heat Exchanger,
Economizer, and Ejector.
Domanski, P. A.
NISTIR 5606; 37 p. March 1995.
Available from: National Technical Information Service
Order number: PB95-216917
air conditioning; ejector; liquid-line/suction-line heat
exchange; Rankine cycle; refrigeration; vapor
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.