Simulation of hybrid heat pumps with two- and three-stage solution circuits for high-lift applications

Book · Fri Nov 01 04:00:00 EST 1996

OSTI ID:392537

Mehendale, S S; Radermacher, R ^[1]

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1. Univ. of Maryland, College Park, MD (United States)

Vapor-compression heat pumps that use absorption technology with two-stage and three-stage solution circuits are investigated by simulation. Ammonia-water is the working fluid. The cycle performance is evaluated for high-temperature-lift applications. The applications include three cooling cases, four heating cases, and a combination of cooling and heating. The two- and three-stage cycle performance is compared with that of the vapor-compression cascade cycle and the single-stage vapor absorption cycle. For the combined cooling and heating case and the heating cases, the single-stage cycle is seen to operate at supercritical pressures. The two-stage and three-stage cycles operate below the critical pressure of ammonia and at significantly lower pressure ratios. With a view to improving the coefficient of performance (COP), certain modifications are introduced in the configuration of the cycles. These include passing the vapor from the lowest temperature desorber into and through the next higher temperature desorber instead of mixing separate vapor streams. Similarly, the compressed vapor is absorbed in subsequent absorbers instead of splitting the discharge vapor stream. These changes reduce the irreversibilities associated with the internal heat transfer processes in the cycle and thereby improve the COP. The cooling COP of the two-stage cycle is found to improve by about 27%, while that of the three-stage cycle improves by more than three times as compared with the original versions of these cycles.

• OSTI ID: 392537
• Report Number(s): CONF-960254--
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
ABSORPTION REFRIGERATION CYCLE
COMPUTERIZED SIMULATION
HEAT PUMPS
HYBRID SYSTEMS
PERFORMANCE
THEORETICAL DATA
VAPOR COMPRESSION REFRIGERATION CYCLE
WORKING FLUIDS