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INFLUENCE OF OIL ON REFRIGERANT EVAPORATOR PERFORMANCE. 4. FLOW REGIME AND PRESSURE DROP IN RETURN BEND.

[In Japanese. / En japonais.]

Author(s) : KIM J. S.

Type of article: Article

Summary

THE COMPACT HEAT EXCHANGER OF THE SERPENTINE TYPE IS MADE MAINLY OF MANY STRAIGHT AND CURVED PIPES, THE LATTER PROVIDING 180 DEG U-BENDS. ALTHOUGH ALMOST HALF OF THE HEAT-TRANSFER AREA IS OCCUPIED BY THE CURVED SECTION, UP TO NOW THERMAL AND HYDRAULIC CHARACTERISTICS OF THIS SECTION HAVE BEEN PREDICTED ASSUMING A STRAIGHT TUBE. THE EXISTENCE OF VIOLENT SECONDARY FLOW AND VORTEX, THE FLOW DIRECTION CIRCULATING DOWNWARDS OR UPWARDS, MIGHT BE AN IMPORTANT FACTOR IN DETERMINING EVAPORATOR PERFORMANCE. THE EXPERIMENT COMPARED VARIATION OF THE SYSTEM MASS VELOCITY (100-250 KG/M2.SEC), MASS CONCENTRATION OF LUBRICATION OIL (0-9%) AND THERMAL EQUILIBRIUM VAPOUR QUALITY (0.1-1.2). THE TEMPERATURE OF THE OUTSIDE WALL AND THE PRESSURE DROP WERE MEASURED AND FLOW PATTERN WAS OBSERVED. AS A RESULT, THE FLOW DISTURBANCE AT THE DOWNSTREAM OF THE U-BEND WAS VIOLENT AT THE WAVY AND STRATIFIED FLOW REGIME, AND THE STRONG EFFECT OF LUBRICATION OIL WAS WAS 5 TIMES LARGER THAN THROUGH THE STRAIGHT TUBE.

Details

  • Original title: [In Japanese. / En japonais.]
  • Record ID : 1991-0579
  • Languages: Japanese
  • Source: Trans. JAR - vol. 6 - n. 1
  • Publication date: 1989
  • Document available for consultation in the library of the IIR headquarters only.

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