ISSN Online: 2377-424X
ISBN Print: 0-89116-559-2
International Heat Transfer Conference 8
BOILING HEAT TRANSFER DETERIORATION IN THE BEND OF VERTICAL U-SHAPED TUBES
Abstract
This paper describes the experimental results on the boiling heat transfer deterioration in the bend of а Ø25×2 mm vertical U-shaped tube with the radius of 700 mm under the conditions of P = 4.5−14.4 MPa, G = 800-2000 kg/(m2 s) and q = 80-330 kw/m2 in our high pressure electrically heated water loop. The circumferential wall temperature profile along the bend was obtained. The wall temperature in inner side of the bend was found to increase in the range of φ = 45−105° at low st earn qualities and reach its peak value at φ = 75 . The temperature difference between the inner side and outer side of the bend was seen to vary with the mass velocity, steam quality, heat flux and pressure. The variation of Δt was found to reflect the influence of the two-phase flow pattern transitions. Application of the present results to the design suggests that the avoidance of stratified and intermittent flow is important for insureing isothermality.