Experimental CHF and MHF correlations in transient boiling systems with vertical rectangular parallel plates

The objectives of this article are to propose critical heat flux (CHF) and minimum heat flux (MHF) correlations in transient forced-convective boiling systems and to investigate the parametric effects on CHF and MHF. Experiments were conducted to obtain the CHF and MHF values in forced-convective boiling systems with vertical, parallel, rectangular channels between parallel plates. A nondimensional transient parameter, T=(Z²/α_fT_sat)(dt_w/dt)_CHFwas adopted to quantify the transient effects on CHF and MHF values. Experimental ranges are 718.0-2162.0 kg/m² s for mass flux, 7.5-20.3°C for inlet subcooling, and 3.0-8.0 mm for channel gap distance. The system pressure is l.Oatm. The results show that CHF and MHF increased with increasing inlet subcooling. It was also found that CHF and MHF increased somewhat linearly with increasing mass flux at the top of the test section, while they were weakly dependent on the mass flux at the bottom of the test section. New CHF and MHF correlations were developed for upward flow in transient boiling heal transfer with maximum error bands of ±18% for CHF and ±30% for MHF.