Effect of Geometric Arrangement

Inasmuch as a difference in testing techniques exists between different observers, a comparison of data for geometric arrangements from different laboratories is unwise. Only data from one laboratory for each case will be included in this section. 

Both horizontal and vertical plates were used by Jakob and Linke (J4) for nucleate boiling of water at low heat fluxes. The results were nearly identical for these two cases. No other data are available for comparing orientation of plates. 

The effect of diameter has been tested for horizontal hot wires. Rinaldo (M3) used diameters of 0.024 in. and less. The data are shown in Fig. 32. The values at the lowest temperature differences are due probably to free convection rather than to boiling. For the range of 

Data from a single laboratory for tubes of different diameters are needed. Tubes are thicker than the bubbles produced, but the reverse is true for wires. The diameter effects may not be the same in the two cases. The equations of Rohsenow and of Forster and Zuber predict that the geometric arrangement is of no consequence. The prediction is not proved at present. 

Bonilla for these critical values plotted in such a way as to obtain a fairly good correlation. The optimum pressure for these six liquids is at about 35% of their critical pressures. 

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