Initial parametric results using CYCLEZ---An LMTD-specified, Lorenz-Meutzner cycle refrigerator-freezer model
A computer model representing a two-evaporator, two-intercooler refrigerator-freezer operating at steady-state with nonazeotropic refrigerant mixtures (CYCLEZ) has been developed at Oak Ridge National Laboratory (ORNL). This model is being used to assess the effects of system design and operating parameters on the cycle performance of a refrigerator-freezer designed around the Lorenz- Meutzner (L-M) circuit. Separate evaporators for the freezer and fresh-food compartments are modeled, as well as two intercoolers that subcool liquid refrigerant from the condenser by heat transfer with low-pressure refrigerant. The CYCLEZ refrigerator/freezer model is derived form the CYCLEZ heat-pump model developed originally by the National Institute of Standards and Technology (NIST). CYCLEZ currently uses the Carnahan-Starling-DeSantis (CSD) equation-of-state to compute refrigerant thermodynamic properties , so that new refrigerants can easily be added. Condenser and evaporator heat-exchanger performance are defined by user-specified overall LMTDs which allow equivalent heat-exchanger sizing per unit refrigeration load to be maintained for different refrigerant mixtures. A more consistent formulation of overall heat-exchanger LMTD is applied across the condenser superheated and two-phase regions as well as over the two evaporators. Source and sink conditions are specified in terms of inlet and outlet temperatures of the external fluid streams. Intercooler high-side (subcooling) {delta} Ts and relative fresh-food-to-freezer load ratio are also user-specified. These features make this model well suited for evaluating the optimal thermodynamic cycle requirements of the five heat exchangers used in the L-M refrigerator/freezer circuit. 13 refs., 6 figs., 1 tab.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- Sponsoring Organization:
- DOE/CE; EPA
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 7174269
- Report Number(s):
- CONF-900742-1; ON: DE90010146
- Country of Publication:
- United States
- Language:
- English
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C CODES
CLOSED-CYCLE COOLING SYSTEMS
COMPARATIVE EVALUATIONS
COMPUTER CODES
COMPUTERIZED SIMULATION
COOLING SYSTEMS
DISPERSIONS
EFFICIENCY
ENERGY EFFICIENCY
ENERGY SYSTEMS
ENERGY TRANSFER
EVAPORATORS
FLUIDS
FOOD INDUSTRY
FUNCTIONS
HEAT EXCHANGERS
HEAT PUMPS
HEAT TRANSFER
HEATING
INDUSTRY
MIXTURES
OPTIMIZATION
PERFORMANCE TESTING
PRESSURE EFFECTS
REFRIGERANTS
SATURATION
SIMULATION
STANDARDS
SUPERHEATING
TESTING
THERMODYNAMICS
TRANSFER FUNCTIONS
WORKING FLUIDS