Boiling suppression factor

Figure 4.13 Boiling suppression factor S [Eq. (4-17)]. (From Chen, 1966. Copyright 1966 by American Chemical Society, Washington, DC. Reprinted with permission.)... 

From Figure 12.57 the nucleate boiling suppression factor, = 0.23... 

Here p, is the pressure scaled by a critical pressure, and the wall roughness Rp was 5 pm. The forced convection heat transfer enhancement factor and boiling suppression factor were used as in [27] ... 

Likewise, the microscopic heat-transfer term takes accepted empirical correlations for pure-component pool boiling and adds corrections for mass-transfer and convection effects on the driving forces present in pool boiling. In addition to dependence on the usual physical properties, the extent of superheat, the saturation pressure change related to the superheat, and a suppression factor relating mixture behavior to equivalent pure-component heat-transfer coefficients are correlating functions. 

The part a B emanating from the bubble formation is based on the heat transfer coefficient aB in nucleate boiling in free flow. However because the temperature rise in the boundary layer of a forced flow is steeper than in free flow nucleate boiling, more heat will be released from the wall by conduction and the bubble formation will be partially suppressed in comparison to that in free flow. Chen accounted for this effect with a suppression factor S < 1, which the heat transfer coefficient aB in nucleate boiling in free flow is multiplied by, a B = SaB. 

Here aB is the heat transfer coefficient for nucleate boiling from section 4.2.6, and ac is that for forced, single phase flow, sections 3.7.4 and 3.9.3 The special case of S = F = 1 in saturated boiling heat transfer is included in the equations above. The factors S (suppression factor) and F (enhancement factor) are yielded from... 

For cases where both forced convective heat transfer and nucleate boiling are significant, then the power-law interpolation and suppression-type correlations can be employed. The nucleate boiling component is adjusted for the effect of multiple components as described earlier. Yoshida et al. [285] have developed a suppression-type correlation, and Winterton [286] describes the application of the Liu and Winterton [287] correlation to multicomponent mixtures the Liu and Winterton correlation is of a hybrid type that includes a suppression factor on the nucleate boiling component but that uses the power-law interpolation with n = 2 in Eq. 15.226. 

Post, S.M., E.C. de Wit, and H.M. Princen (1997). Cafestol, the cholesterol-raising factor in boiled coffee, suppresses bile acid synthesis by downregulation of cholesterol 7a-hydroxy-lase and sterol 27-hydroxylase in rat hepato-cytes. Arterioscler. Thromb. Vase. Biol. 17, 3064-3070. 

The linkage between the enhancement of heat transfer at boiling of dilute polymer solutions and the elastic properties of the system is confirmed by the existence of the optimal concentration corresponding to (Figure 7.2.14). Similar optimal concentration was established in addition of polymers to water to suppress turbulence - the phenomenon that also owes its origin to elasticity of macromolecules. Therefore, it is possible to expect that the factors favoring the chain flexibility and increase in the molecular mass, should lead to strengthening of the effect. 

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