Convection Heat Transfer Ch 6 Fundamental Concepts Ch 7 庄xternal flow .Heat Ch 8 Internal flow transfer Ch 9 Free convection coefficient Sh 10 Convection with phase change Ch 11 Heat exchanger
Convection Heat Transfer • Ch 6 Fundamental Concepts • Ch 7 External flow • Ch 8 Internal flow • Ch 9 Free convection • Ch 10 Convection with phase change • Ch 11 Heat exchanger •Heat transfer coefficient
Chapter 6 Principles of Convection >Boundary Layers >Laminar and Turbulent Flow Chapter 6 2
Chapter 6 2 Chapter 6 Principles of Convection ¾Boundary Layers ¾Laminar and Turbulent Flow
Introduction to Convection Convection heat transfer (HT)denotes energy transfer between a surface a fluid moving over the surface. The dominant contribution is due to the bulk(or gross)motion of fluid particles. General idea of convective HT problems: (1)simple convection problems between a surface a fluid (liquid gas) (2)between a liquid and a gas across the interface (with direct contact) (3)between two immiscible liquids across the interface. Chapter 6 3
Introduction to Convection Chapter 6 3 • Convection heat transfer (HT) denotes energy transfer between a surface & a fluid moving over the surface. • The dominant contribution is due to the bulk (or gross) motion of fluid particles. General idea of convective HT problems: (1) simple convection problems between a surface & a fluid (liquid / gas) (2) between a liquid and a gas across the interface (with direct contact) (3) between two immiscible liquids across the interface
The Mechanism of Convection Convection is not a basic heat transfer mechanism: If the fluid were perfectly at rest,heat is transferred into the fluid by molecular conduction. .Temperature gradients transfer of heat are in a direction normal to the surface. uly)a A solid surface and a fluid exchanging heat with it. Chapter 6 4
Chapter 6 4 The Mechanism of Convection Convection is not a basic heat transfer mechanism: • If the fluid were perfectly at rest, heat is transferred into the fluid by molecular conduction. • Temperature gradients & transfer of heat are in a direction normal to the surface. A solid surface and a fluid exchanging heat with it
The Mechanism of Convection T(y) .The first layer of fluid adheres to the surface because of viscous friction (no-slip condition at the wall.ie,v,velocity of surface itself) In subsequent layers,the velocity increases progressively to Uo In the first layer (no slip layer),heat transfer by conduction. other layers,also conduction. Velocity gradient exists,the fluid moving from warmer to colder part carries the stored heat (i.e,enthalpy). Chapter 6 5
Chapter 6 5 The Mechanism of Convection •The first layer of fluid adheres to the surface because of viscous friction (no-slip condition at the wall. ie, vs = velocity of surface itself) • In subsequent layers, the velocity increases progressively to U∞ • In the first layer (no slip layer), heat transfer by conduction. other layers, also conduction. • Velocity gradient exists, the fluid moving from warmer to colder part carries the stored heat (i.e, enthalpy)