Enhanced boiling heat transfer surfaces

✍ Scribed by R.G. Scurlock

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 617 KB
• Volume: 35
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/0011-2275(95)90826-2

✦ Synopsis

The concept of enhanced boiling and the advantages to be gained in cryogenic plant are discussed. Experimental results are reported in liquid nitrogen, argon, oxygen and R12. The saturated boiling heat transfer chracteristics of flat surfaces are significantly enhanced by plasma spraying of porous pure aluminium and aluminium/silicon coatings. Such coatings possess heat transfer coefficients up to 10 times those for smooth untreated surfaces. The experimental results demonstrate there is an optimum thickness of plasma sprayed coating for each liquid and selected heat flux, in order to achieve maximum heat transfer coefficient. The effect of fouling by impurities has been studied, and the results suggest that smooth surfaces may show greater degradation in heat transfer performance than porous surfaces. Application of experimental results from small surfaces to the large reboiler/condensers used in cryogenic plant require consideration of the major differences between local boiling heat transfer at constant heat flux (laboratory condition) and constant wall temperature (cryogenic plant condition).