To develop compact space heat exchangers, experiments on the increase of CHF for narrow heated ducts between parallel plates are conducted. Fine grooves are machined on the surface of heat transfer side, and liquid is supplied underneath flattened bubbles by capillary pressure from auxiliary liquid channels separated from the main channel by porous metal plates. With this structure, values of CHF for the heating surface are increased up to twice as much as those without the structure. Effect of inlet liquid velocity on CHF values is also investigated. At an optimum flow rate, values of CHF take the maximum for a given liquid subcooling. Teh increase in CHF values is expected to become much higher when the duct is elongated and/or gravity level is reduced.
