Heat transfer2

Thermal insulation

For decrease the heat loss should be use thermal insulation such as:

1.   Cork: is good insulator but it charred at moderate temperature.

2.   85% magnesia with asbestos.

3.  Glass wool

When increasing the thickness of lagging will

reduce the loss of heat (Economic)  

Source of heat energy

1.   Direct heat: transfer heat from electrical resistance heater.

2. Indirect heat: is a two steps process the first began with the transfer of heat energy from the one system to heat transferring agent and the second being from the heat transferring agent to the second system. The lab should be free from dust or microorganism.               

Heat transferring agent as steam, water & air

Type of steam:

1. Saturated steam (wet)

2. Unsaturated steam (dry)

3. Super heated steam

Equipments

1. Finned tube exchanger 

Disadvantage:

1. Washing of it is difficult

2. No thermal conductivity constant

2. Plate heat exchanger

It is the best in heating but difficult in cleaning.