The GATE Grind

GATE 2023 CH – Question 46

Heat Transfer · Boiling, condensation and evaporation · 2 marks · Multiple select

Which of the following statements is/are CORRECT?

  1. Bond number includes surface tension.
  2. Jakob number includes latent heat.
  3. Prandtl number includes liquid-vapor density difference.
  4. Biot number includes gravity.

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Show answer and explanation

Correct answer: (A) Bond number includes surface tension.; (B) Jakob number includes latent heat.

Explanation

The Bond number, $\frac{\Delta\rho gL^2}{\sigma}$, contains the surface tension $\sigma$ (A). The Jakob number, $\frac{c_p\Delta T}{h_{fg}}$, contains the latent heat (B). The Prandtl number is $\frac{c_p\mu}{k}$ and has no density difference (C false), and the Biot number $\frac{hL}{k}$ has no gravity (D false).