ABSTRACT
Boiling heat transfer to binary mixtures of HFC-134 a(more volatile) and HCFC-123(less volatile) flowing in a uniformly heated vertical tube, 10mm i.d., and 2000mm heated length, was experimentally investigated to obtain new experimental data required for discussion about mixture effects on nucleate boiling and two-phase convection heat transfer.
In the low quality region where nucleate boiling is likely dominant, the mixtures gave lower heat transfer coefficients than either those of an equivalent single component of the same physical properties, or those predicted from a linear interpolation of heat transfer coefficients of the two pure components. This observed mixture effect is as usual in pool boiling.
In the two-phase convection region at higher quality where nucleation is supposed to be fully suppressed, heat transfer coefficients of the mixtures were neither noticeably reduced nor dependent on heat flux.
