THE EMPIRICAL CORRELATION FOR HEAT TRANSFER AND PRESSURE DROP IN SINGLE-PHASE TURBULENT FLOW INSIDE INTERNALLY HELICAL-GROOVED HORIZONTAL SMALL-DIAMETER TUBES
An experimental study into pressure drop and heat transfer in single-phase turbulent flows was carried out using 10 types of internally helical-grooved tubes and smooth small-diameter tube with an outside diameter of 4.00 mm.The geometric groove parameters for the test heat-transfer tubes were: number of grooves (40 to 50); helix angle (0° to 25°); and fin height (0.1 to 0.2 mm).In the experiments,water was used as a test fluid; the inlet temperature was kept constant at 20℃; and the flow rate was varied from 0.001 to 0.047 kg/s.Nichrome wire is used to electrically heat the test tubes.The wall temperature of the test tubes is measured by using the change in the electrical resistance caused by the temperature change.The pressure drop is measured by a distortion-type differential pressure transducer.The results showed: (1) In the turbulent flow region,fin height had the greatest effect,helix angle had only a minor effect,and the number of grooves had almost no effect upon the pressure drop versus the mass flow rate of the 4 mm grooved small-diameter tubes.(2) In the turbulent flow region,the heat-transfer coefficients of the 4 mm grooved small-diameter tubes were greatly affected by fin height.The heat-transfer coefficients became the maximum when a helix angle was near 15°,and there is a different tendency in the experiments of the pressure drop.On the other hand,there is almost no effect of the number of grooves.(3) The new empirical correlations for the friction factor and heat-transfer coefficient were developed based on the experimental values,which can predict experimental values within ±15% and ±25%,respectively.
ICHINOSE J INOUE N
National Fisheries University,2-7-1 Nagata-Honmachi,Shimonoseki,759-6595,Japan Tokyo Univ.of Marine Sci.& Tech.,2-1-6 Etchujima,Koto-ku,Tokyo 135-8533,Japan
国际会议
西安
英文
1-8
2012-08-26（万方平台首次上网日期，不代表论文的发表时间）