ISSN Online: 2377-424X
ISBN Print: 0-89116-559-2
International Heat Transfer Conference 8
HEAT TRANSFER IMPROVEMENT IN NUCLEATE BOILING THROUGH APPLICATION OF POORLY WETTABLE NUCLEATION ACTIVATORS
Abstrakt
In nucleate boiling the heat transfer can be considerably improved by locating porous poorly wettable solids as nucleation activators close to the heated surface. Woven and knitted fabrics of PTFE multifilament yarn have been found to be efficient nucleation activators for boiling water. The mesh size of the fabric can be optimized in order to obtain maximum heat flux density or minimum surface superheat for a chosen type of liquid at a fixed boiling pressure. For well wetting refrigerant R 113 heat transfer improvement by application of PTFE fabrics is smaller than for water but still important.
Retardation of boiling and hysteresis of the boiling curve is eliminated by applying nucleation activators. After five hours of operation no further shift of the boiling curve has been found during the following 150 hours.
Retardation of boiling and hysteresis of the boiling curve is eliminated by applying nucleation activators. After five hours of operation no further shift of the boiling curve has been found during the following 150 hours.