Tubeside condensation of nonazeotropic refrigerant mixtures for two enhanced surfaces

Conference · Mon Jan 01 04:00:00 EST 1990

OSTI ID:6117005

Conklin, J C; Vineyard, E A

As part of the Building Equipment Research program at Oak Ridge National Laboratory (ORNL), nonazeotropic refrigerant mixtures (NARMs) are being investigated to replace chlorofluorocarbon compounds. The condensation of NARMs is not isothermal, and this can improve the heat exchanger effectiveness of a condenser as well as improve thermodynamic cycle efficiencies. The total condensing heat transfer coefficients for refrigerant R22 and for four nonazeotropic mixtures of refrigerants R143a and R124 were measured and are presented as a function of mass flux for two inside tube surfaces, one having spiral ridged fins and the other having a spirally corrugated or fluted surface. The total condensing coefficient for the finned tube is higher than that for the fluted tube at any given refrigerant mass flux for all the refrigerant mixtures. The measured irrecoverable pressure drop for the finned tube was approximately half that for the fluted tube; thus, the finned tube has the better thermal performance of the two enhanced tubes. The condensing heat transfer coefficient is also presented as a function of the mass fraction of R143a for three values of mass flux. Degradation of the condensing coefficient for intermediate values of R143a mass fraction is apparent, but has different trends with respect to mass flux for the two enhanced surfaces; thus, the geometry of the enhanced surface appears to affect the physical mechanism for condensation of NARMs. 13 refs., 9 figs.

• Research Organization: Oak Ridge National Lab., TN (USA)
• Sponsoring Organization: DOE/CE
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6117005
• Report Number(s): CONF-910318-8; ON: DE91004541
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320106* -- Energy Conservation
Consumption
& Utilization-- Building Equipment-- (1987-)
36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure & Phase Studies
BUILDINGS
DISPERSIONS
EFFICIENCY
ENERGY EFFICIENCY
ENERGY TRANSFER
FLUIDS
GASES
HEAT EXCHANGERS
HEAT TRANSFER
MATHEMATICAL MODELS
MIXTURES
PHASE TRANSFORMATIONS
REFRIGERANTS
THERMODYNAMIC CYCLES
TUBES
VAPOR CONDENSATION
VAPORS
WORKING FLUIDS