Investigation of the mechanism of nucleate boiling through numerical modeling

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:7255281

Lee, R C

The fundamental mechanisms accounting for the enhanced heat transfer in nucleate boiling caused by individual bubbles are difficult to quantify analytically or experimentally. A comprehensive, self-consistent numerical model has been developed to quantify these fundamental mechanisms and provide a clearer picture of the processes that occur at this microscopic level. A numerical grid generation technique was employed to transform the complicated and time-dependent geometry of a nucleate boiling bubble during growth and departure, and the axisymmetric Navier-Stokes and energy equations applied to the bulk fluid field were solved using a finite-difference formulation. The specific boiling situation chosen for simulation was saturated water at one atmosphere pressure and 8.5 K wall superheat. The results clearly indicate that microlayer evaporation is the dominant heat-transfer mechanism for this situation both in terms of energy for bubble growth and enhanced wall heat transfer. For the conditions considered, microlayer evaporation provided 90% of the energy for bubble growth and 87% of the enhanced wall heat transfer. In contrast, enhanced wall convective effects were essentially non-existent during growth and minimal following departure.

• Research Organization: Wyoming Univ., Laramie (USA)
• OSTI ID: 7255281
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420400* -- Engineering-- Heat Transfer & Fluid Flow
BOILING
BUBBLES
ENERGY TRANSFER
EVAPORATION
FINITE DIFFERENCE METHOD
HEAT TRANSFER
HEATING
ITERATIVE METHODS
LAYERS
NUCLEATE BOILING
NUMERICAL SOLUTION
PHASE TRANSFORMATIONS
SUPERHEATING
WALLS