Experimental investigation on heat transfer characteristics of upward flow boiling in a vertical narrow rectangular channel

Heat transfer experiment on water flow boiling was carried out in the upward direction under atmospheric pressure through a narrow rectangular channel heated on one-side by vapor having a gap of 2.75 mm, a width of 250 mm, and length of 1400 mm. The heat transfer coefficient and thermal hydraulic thresholds of the flow boiling in forced convective flow, such as the onset of nucleate boiling (ONB) and onset of fully developed nucleate boiling (OFDB) were investigated. The experiment was performed over a wide range of inlet temperature (75-95 & DEG;C), mass flow rate (2-9 g/m), and heat fluxes (5-16 kW/m2). The effects of the parameters on the heat transfer coefficients have been discussed in detail. A series of ONB, FDB and heat transfer correlations were evaluated using the experimental data, and most of the correlations did not adequately fit the experimental results. A modified Hong et al. correlation and modified Zhu et al. correlation were used to predict the wall superheat at ONB and FDB respectively. The average errors (AEs) of the two correlations were 2.36% and -0.68%, and the root mean square errors (RMSEs) of them were both 14.00%. A modified Li and Wu correlation was used to predict heat transfer coefficients with the average error (AE) of 1.46% and the root mean square errors (RMSE) of 11.88%.

Automated summary

In this experiment, a narrow rectangular channel was used to study the heat transfer performance of water flow boiling in the upward direction under atmospheric pressure. The heated side of the channel had a gap of 2.75 mm, a width of 250 mm, and a length of 1400 mm. The heat transfer coefficient and thermal hydraulic thresholds were investigated for forced convective flow boiling, including the onset of nucleate boiling (ONB) and onset of fully developed nucleate boiling (OFDB). The effects of inlet temperature, mass flow rate, and heat fluxes on the heat transfer coefficients were discussed. Correlations for ONB, FDB, and heat transfer were evaluated, but most of them did not fit the experimental results well. Modified correlations by Hong et al. and Zhu et al. were used to predict wall superheat at ONB and FDB, with average errors of 2.36% and -0.68%, and root mean square errors of 14.00% for both. A modified correlation by Li and Wu was used to predict heat transfer coefficients, with an average error of 1.46% and a root mean square error of 11.88%.