HEAT-TRANSFER IN INTERMITTENT AIR-WATER FLOWS - PART II - UPWARD INCLINED TUBE

This paper presents a study on the heat transfer in intermittent air-w ater flows in an upward inclined tube. The experimental technique is b ased on infrared thermography of an electrically heated wall of the tu be, providing both visualization of the temperature held and measureme nts of the local wall temperature. Local heat transfer coefficients an d how parameters have been measured for air-water flow in a pipe of 49 .2 mm inner diameter at inclination angles of 2 degrees and 5 degrees. The water and air Froude numbers varied from 0.59 to 2.0 and from 0.0 3 to 0.57, respectively. Experimental correlations of the heat transfe r coefficient indicate that the liquid and gas Froude numbers and dime nsionless frequency of bubble appearance are good correlating paramete rs. A simple physical model was developed to correlate between the flo w parameters and the heat transfer. (C) 1998 Elsevier Science Ltd. All rights reserved.