An experimental investigation of bubble nucleation of a refrigerant in pressurized boiling flows

    Authors

    S. M. S. Murshed; K. Vereen; D. Strayer;R. Kumar

    Comments

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    Abbreviated Journal Title

    Energy

    Keywords

    Flow boiling; Thermo-chromic liquid crystal; Bubble nucleation; Refrigerant; THERMOCHROMIC LIQUID-CRYSTALS; NARROW ANNULAR DUCT; HEAT-TRANSFER; SMALL; CHANNELS; R-134A; THERMOGRAPHY; BEHAVIOR; GROWTH; FLUID; Thermodynamics; Energy & Fuels

    Abstract

    An experimental investigation is performed to determine the effect of system pressure and heat flux on flow boiling and associated bubble characteristics of a refrigerant in a narrow vertical duct. A high-pressure flow boiling test loop was built and TLC (thermo-chromic liquid crystal) was applied to the back of the heater foil for high resolution and accurate measurement of heater surface temperature. Refrigerant R-134a is used as the test fluid at different pressures ranging from 690 to 827 kPa and different heat fluxes to quantify their influence in bubble characteristics such as bubble nucleation, growth, departure, and coalescence. Two synchronized high resolution and high-speed cameras are used to simultaneously capture TLC images as well as bubbling activities at high frame rates. By varying flow rate and system pressure, TLC and bubble images were captured and analyzed. Results show that the bubble generation frequency and size increase with heat flux. An increase in pressure from 690 to 827 kPa increased the bubble frequency and size by about 32 Hz and 20 mu m, respectively. Bubble coalescence was also observed after departure from the nucleation site. (C) 2010 Elsevier Ltd. All rights reserved.

    Journal Title

    Energy

    Volume

    35

    Issue/Number

    12

    Publication Date

    1-1-2010

    Document Type

    Article

    Language

    English

    First Page

    5143

    Last Page

    5150

    WOS Identifier

    WOS:000286343000074

    ISSN

    0360-5442

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