**Nomenclature**

*3.2.3 Conclusion*

*are on the same scale for comparison.*

**Δ***Tsub* **[°C]**

lation:

**Table 8.**

Following critical observations were observed during Condensing bubble simu-

*Condensing bubble shape comparison for varying temperature field [*Dbo *= 2 mm,* ΔTsub *= 5* °*C]. All bubbles*

**Simulation Time,** *t* **[ms] Maximum Rise Velocity**

**(cm/s) <sup>0</sup> <sup>5</sup> 8.75**

**5 6.9**

*Heat Transfer - Design, Experimentation and Applications*

**T\_VARY 6.5**

• Bubble reduction rate depends on the liquid subcooling and bubble velocity.

• Same is true for the bubble velocity. The interfacial (convective) heat transfer coefficient (*hif*) is proportional to the bubble velocity. As such, higher the

• Precaution should be taken during the selection of an appropriate Condensate Nusselt number (*Nucond*) correlation. As the numerical results can vary

• Bubble deforms at a higher rate for larger bubble sizes during ascend. For higher surface tension force, smaller bubbles tend to keep their original spherical shape.

• Liquid subcooling also contributes to the bubble shape determination as heat and mass transfers across the interface cause distortion. With higher liquid subcooling, bubbles get smaller quickly and maintain spherical shape.

• When an adiabatic bubble is released from a stationary position, the rise

velocity of the bubble continues to rise until it reaches a stable velocity regime. Whereas for condensing bubble, the rise velocity is always changing for

• With the increase of liquid subcooling, rise velocity of the condensing bubble

• With the increase of fluid flow velocity, both bubble condensation rates and

• Varying temperature field in this particular instance had minimal effects on

Higher the liquid subcooling higher the bubble reduction rate.

significantly and should be chosen based on the applications.

bubble velocity higher the bubble condensation rate.

continual heat and mass transfers.

shape deformation increase.

condensing bubble size and shape.

increases.

**140**

