Abstract: Natural convective boiling in a confined narrow space is frequently encountered in engineering,but there is very little information on heat transfer obtained from boiling in narrow channels with symmetric heating yet.Experiments have been performed for R-113 in narrow vertical channels which consist of a pair of flat,transparent or porcelain,and isoflux plates,The plates were made by a new technique of plating electric heating film,The effects of gap sizes,peripheral and heating conditions and heat fluxes on boiling incipience,boiling flow pattern,and heat transfer are studied systematically,The results based On the observation and measurement illustrate that the boiling flow pattern depends on gap size and heat flux.The incipient heat flux decreases with decreasing gap size. Dimensionless heat flux relationship is obtained.

Key words: narrow spaceboiling, heat transfer, heat flux