Thermostatic Expansion Valve

This type of thermostatic is used in industrial and commercial refrigeration system. This is an expansion device, and it is also known as constant superheat valve.

In this ther are many different types of elements presented like evaporator, adjusting screw, feeler bulb, diaphragm, spring, valve, strainer.

Let,

Pb- pressure in the bulb.

Ps - pressure in the spring

Pe - pressure in the evoparator.

It is said to be in equilibrium state when the pressure in the bulb is equal to the sum of thepressure in the spring and evaporator. Then it is known as state of equilibrium.

Pb= Ps+Pe.

Power fluid.

Power fluid is contained with the liquid refrigerant. It is used to measure the temperature of the vapour coming out of the evaporator coil, a feeler bulb is placed near the outlet of the evaporator coil.

The diaphragm deflects downwards due to the cooling load increases by this more quantity of refrigerant enters into the valve.

.•. Pb>(Ps+Pb).

When the cooling load decreases the diaphragm is used to move upwards.

.•. Pb<(Ps+Pe).

These values are also used commonly in airconditioning system and refrigeration system.