Flooded Evaporator – Parts, Working, Advantages, Disadvantages, and Applications

A flooded evaporator is a device that is used in refrigeration systems as a heat exchanger which absorbs heat from the object or environment to be cooled.
It is a very efficient evaporator that has a very high heat transfer rate.
It is known as a flooded type evaporator as a large amount of refrigerant is present in this evaporator i.e. the evaporator tubes are always completely filled with liquid refrigerant.

This device is used in refrigeration systems for the clean running of refrigeration systems by maintaining constant refrigerant liquid levels.

Parts Of Flooded Evaporator :

1) Float Chamber:-
The main function of the float chamber is to store the refrigerant coming from the condenser.
It is called a float chamber because a floating object is present inside it.
The floating object is connected to a valve. The float valve and the floating chamber together are used to control the passage of liquid refrigerant inside the flooded evaporator.

2) Float:
The float is present inside the float chamber and is used to start and stop the supply of liquid refrigerant into the accumulator.

3) Inlet Pipe:
The inlet pipe is used to supply the liquid refrigerant to the float chamber.

4) Accumulator:
The accumulator is used to store the liquid refrigerant inside the flooded evaporator. The level of liquid in the accumulator and the float chamber is always the same whether its level increase or decreases.

5) Suction Pipe:
A suction pipe is to suck the vapor refrigerant and pass it to the compressor.

6) Evaporator Tubes:–
The liquid refrigerant from the accumulator passes to the evaporator tubes. The liquid refrigerant passes through the evaporator tubes. This passage is in the form of tubes so that the contact with the object to be cooled can be maximized.

7) Compressor:-
The compressor is used for the compression of vapor refrigerant. In the compressor, the vapor gets compressed at high pressure and is converted into hot high-pressure gas.

Working Of Flooded Evaporator :

First, let’s see how the entry of the refrigerant in this evaporator works:
The passage of the refrigerant inside the evaporator is controlled using a float chamber and valve.
There is a float inside the floating chamber which is connected to a valve. This valve is connected to a condenser from where the liquid refrigerant is transferred.
When this valve opens the liquid refrigerant enters the evaporator.
This valve opens when the float in the float chamber moves down due to the low level of refrigerant in the floating chamber.
As the float moves down the valve opens as both are connected to each other.

When the valve opens refrigerant pass through the valve and enters the floating chamber. As the refrigerant starts filling the float chamber, the float again moves up and the valve closes.
In this way, the valve closes when the required amount of refrigerant enters the float chamber.
In this way, the passage of refrigerant inside the flooded evaporator is controlled by a floating chamber and valve.

After the float chamber, the refrigerant is passed to the accumulator.The accumulator accumulates the liquid refrigerant inside the flooded evaporator.
From the accumulator, the liquid refrigerant is passed to the evaporator tubes.
The evaporator tubes are arranged in such a shape sothat there is maximum contact between the evaporator tubes with the object to be cooled.

Inside the evaporator tubes, the liquid refrigerant takes heat from the object to be cooled and gets converted into vapor.
So, in the evaporator tubes, there are both vapor and liquid particles.
After passing through the evaporator tubes, the refrigerant present in liquid and vapor form is again sent to the accumulator.
In this accumulator, baffles are fitted which allows the vapor refrigerant to pass but trap the liquid refrigerant, and this liquid refrigerant again gets trapped in the baffles and gets accumulated in the accumulator.

From the accumulator, the vapor refrigerant is passed to the compressor and in the compressor, the vapor refrigerant is pressurized and is turned into hot, high-pressure gas which is further transferred to the condenser.
In the condenser, the vapor refrigerant releases the heat which was absorbed in the evaporator tubes and turns into liquid refrigerant.
This liquid refrigerant is again transferred to the flooded evaporator through the float chamber and in this way, the cycle continues.

Advantages Of Flooded Evaporator:

1) One of the main advantages of flooded refrigerant is that the poor distribution in the evaporator is reduced.
2) Flooded evaporator has high transfer rates. So the small size of the flooded evaporator can do the same work as the larger size of other types of evaporator can.
3) In the flooded evaporator the refrigerant completely fills the evaporator coil so the heat transfer is much more efficient and cooling is improved.
4) The chances of frost formation is much lower in this type of evaporator.

Disadvantages Of Flooded Evaporator:

1) Not suitable for small-scale systems or applications.
2) It has a complex design and requires additional components which increases the maintenance and overall cost of the evaporator.

Applications Of Flooded Evaporator:

1) Flooded evaporators are used in large installations, especially in chemical and food processing industries.
2) It is used in multi-evaporator systems.
3) It is also suitable for refrigeration systems where load fluctuation is higher.