Gas/liquid flow in plate-and-frame heat exchangers - Part II: Two-phase multiplier and flow pattern analysis

Pressure drop data measured during adiabatic two-phase flow in a plate-and- frame heat exchanger (PHE) are normalized with respect to the single-phase liquid pressure drop to give two-phase multipliers. A curve-fitted equation defines this relationship, which is a strong function of the Lockhart-Mart inelli parameter C coefficients are shown to be strong functions of both th e Lackhart-Martinelli parameter and liquid viscosity making this correlatio n unsuited to predictions of pressure drop in PHEs. Interfacial structure, observed during air-water downflow in replica channe ls (d(C) = 3 mm), is categorized into five flow patterns. These have a numb er similarities with structures reported for circular and rectangular chann els of similarly low hydraulic diameter The transition boundaries between t he patterns are shown to be a function of the chevron angle.