LOW HEAT-FLUX BOILING (thesis). Quarterly Progress Reports No. 6, 7, AND 8, October 1, 1962-July 1, 1963
This investigation presents experimental data from tests of boiling saturated distilled water from the outer surface of a horizontal tube at low values of heat flux, 5,000 to 100,000 Btu/hr-ft/sup 2/, and elevated pressures, 535 to 1550 psia. Both natural convection (pool boiling) and water velocities up to 4.7 ft/sec normal to the axis of the tube are studied. The design of a system to carry out the boiling studies at pressures up to 2000 psia and temperatures up to 635 deg F is discussed in detail. The results are presented in a series of figures which show the heat flux as a function of wall superheat, (T/sub w/ --T/ sub sat/, for pressures of 535, 1015, and 1550 psia and velocities of 1.3 and 4.7 ft/sec, as well as pool boiling. A pronounced hysteresis effect is noted, with a higher wall superheat required at a given flux for increasing heat flux. The curve for decreasing heat flux is more stable and reproducible. An empirical equation which fits the pool boiling data in the range of 535 to 1550 psia, for the decreasing heat flux condition, is (q/A) = 13,700 sup p*), where f(p/sup */) = 1.56(p/sup *//sup 1/6/ and q/A) is heat flux, Btu/hr-ft/sup 2/, p/sup */ is the reduced pressure, , deg F. The effect of a velocity normal to the tube is to reduce the wail superheat at a given heat flux. It is concluded that the heat' flux in nucleate boiling of water is proportional to the wall superheat raised to a power between 1.7 and 2.1. The effect of increasing the system pressure in the range studied is to decrease the wall superheat at a given flux. The effect of heat flux history is significant for tests of up to several hours. The temperature difference appears to approach an asymptotic value for prolonged boiling at constant heat flux, regardless of the prior heat flux from the surface. (auth)
- Research Organization:
- Michigan. Univ., Ann Arbor. Coll. of Engineering
- DOE Contract Number:
- AT(38-1)-260
- NSA Number:
- NSA-17-037336
- OSTI ID:
- 4647336
- Report Number(s):
- TID-19371; ORA-04653-5-P
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- United States
- Language:
- English
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