Simple Method of Composition Shifting With a Distillation Column for a Heat Pump Employing a Zeotropic Refrigerant Mixture.
Simple Method of Composition Shifting With a
Distillation Column for a Heat Pump Employing a
Zeotropic Refrigerant Mixture.
Rothfleisch, P. I.
NISTIR 5689; 27 p. July 1995.
Sponsor:Environmental Protection Agency, Research Triangle Park,
Available from: National Technical Information Service
Order number: PB95-255821
heat pumps; air conditioning; distillation; refrigerant
mixtures; refrigeration; zeotropic refrigerants
This work presents a simplified method of controlling
heat pump capacity by shifting the composition of a
zeotropic refrigerant mixture with a distillation
column. Simplicity is achieved by incorporating the
distillation column into the typical suction accumulator
used by residential heat pumps. A U.S. patent has been
applied for under the title "Accumulator Distillation
Insert for Zeotropic Mixtures". An experimental system
employing this distillation concept has been evaluated
in the laboratory for zeotropic mixtures of R32/134a
(30/70) and R32/125/134a (23/25/52). For the binary
mixture the circulating refrigerant composition was
shifted to R32/134a (54/46). For the ternary mixture
the circulating refrigerant composition was shifted to
R32/125/134a (36/36/28). Seasonal calculations have
shown these composition shifts to reduce the seasonal
resistance heat requirement by up to five percent
compared to R22. Additionally, the instantaneous peak
energy requirement of the dwelling has been reduced
relative to R22 by six to nine percent depending on the
climate region. The distillation insert should be
capable of producing greater composition shifts after
further optimization of the insert and improved
integration with the heat pump system. For the ternary
mixture, it is expected that the insert will be capable
of producing a circulating refrigerant composition
composed entirely of R32/125.