VISCOSITY OF FLUID AND ITS FLOW VELOCITY

Done by:Sean Lee 3S2-12Kenneth Leong 3S3-05Yong Sheng 3S3-22

Introduction

Low velocities and high viscosity causes Laminar Flow

Laminar flow is not good in the transfer of heat energy

Viscosity

Viscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or extensional stress.

Affected by the temperature. Raising the temperature of a fluid

tends to make it less viscous. E.g. Oil stored in the fridge

Viscosity

Low viscosity <2 or <3 centipose(cP).

High viscosity is around 50 centipose(cP).

Tap water has around 1 cP. The more viscous, the slower the fluid flows.

High viscosity, e.g. Glycerol, Honey Directly affects the velocity of the

fluid flowing through the heat exchanger

http://en.wikipedia.org/wiki/File:Viscosity.gif

Viscous fluids in heat exchangers

Sugar Petroleum

Velocity

Low velocities are liquids flowing at <2 or <3 ft/s

High velocities of >10 or >12 ft/s may cause erosion of metal surfaces and should be avoided.

Affects the effiency of heat energy transfer in the heat exchanger, the higher the velocity, the faster the exchange of heat energy.

THE ENDThank you