1. What do you mean by thermal boundary layer? How does the ratio vary with Prandtl number? 2. Defi ne local and mean heat transfer coefficients. On what factors does the value of h depend? 3. Show...

1. What do you mean by thermal boundary layer? How does the ratio

vary with Prandtl number?

2. Defi ne local and mean heat transfer coefficients. On what factors does the value of h depend?

3. Show that the Reynolds number for flow in a circular tube of diameter D can be expressed as Re = 4´/D.