Throttling Devices Used in the Refrigeration and Air Conditioning Systems

-

Throttling Devices or the Expansion Valves Used in the Refrigeration and Air Conditioning Systems


  • Throttling devise is another vital part of all the refrigeration systems and air conditioning systems apart from the compressor, condenser and the evaporator. The refrigerant leaves the compressor at high pressure and temperature and enters the condenser. After leaving the condenser the refrigerant is at medium temperature and high pressure and then it enters the throttling valve. In the throttling valve the pressure and the temperature of the refrigerant is reduced drastically and suddenly. Thus us it is the throttling valve where the temperature of the refrigerant is reduced and it is then able to produce the cooling effect in the evaporator of the refrigerator or the cooling coil of the air conditioner. The throttling valve also controls the amount of the refrigerant that should enter into the evaporator depending on the refrigeration load.

  • What is the Throttling Device or Expansion Valve? How Throttling Devices Work?



    The throttling devise can be the valve or the copper tubing that allows the flow of the refrigerant through very small opening also called as the orifice. The throttling devices allow restricted flow of the refrigerant. The throttling devices are also called as the expansion valves because when the refrigerant passes through them the pressure of the refrigerant drops down or it expands..
    When the refrigerant passes through the orifice its pressure reduces due to friction and also the small opening of the orifice. The amount of the refrigerant flowing through the throttling valve depends on the amount of opening of the orifice. It also depends on the difference of pressure across two sides of the throttling devise that condenser and the evaporator.
    In case of the automatic throttling valve the amount of the opening of the orifice is controlled by the pressure or the temperature in the evaporator. In case of the large refrigeration systems the opening of the orifice is controlled by the level of liquid refrigerant in the condenser or the evaporator. If the throttling valve has fix opening like in capillary tube, the amount of refrigerant flowing through it depends on the pressure towards the inlet side of the throttling valve (condenser pressure) and the outlet side of the throttling valve (evaporator pressure).

  • Functions Performed by the Throttling Devices in Refrigeration Systems


    When the high pressure refrigerant from the condenser enters the throttling devise the pressure of the refrigerant drops down suddenly, due to this the temperature of the refrigerant also drops down suddenly and substantially. There are two important functions performed by the throttling devices or the expansion valves as mentioned below:
    1) Reduce the pressure of the refrigerant: The refrigerant leaving the condenser is at high pressure. The pressure of the refrigerant has to be reduced so that it can vaporize at the required temperature in the evaporator. The small opening or the orifice in the throttling valve reduces the pressure of the refrigerant to the level such that vaporization of the refrigerant occurs. The refrigerant leaving the throttling valve enters the evaporator at low pressure, low temperature and partially liquid and vapor state.
    2) Meet the refrigeration load: The throttling valve also controls the amount of the refrigerant flowing through it and to the evaporator. When there is more refrigeration load that means the quantity of the substance stored in the freezer is more and it is at higher temperature, more amount of heat is to be removed from it. In such cases the throttling devise allows increased flow of the refrigerant through it. When the refrigeration load is less that means the quantity of the substance is less and it is at lower temperature, less amount of heat is to be removed from it. In such cases the throttling valve allows lesser flow of the refrigerant through it.

  • Types of Throttling Devices


    Some of the most commonly used types of throttling valves are:
    1) Capillary tube
    2) Constant pressure or automatic throttling valve
    3) Thermostatic expansion valve
    4) Float valve

Comments

Post a Comment

Popular posts from this blog

Meaning of 1.2L, 1.4L, 1.6L,engine in a car?

-
Image
In a car, which has a multi(4/6/8) cylinder engine, the above nomenclature viz. 1.6L,1.4L, etc. refers to the combined volume capacity of all the cylinders( expressed in cubic centimeters, 1L=1000 cc).  Here volume capacity refers to the swept volume or displacement volume or breathing capacity of the cylinder. It is basically the volume of air that can be sucked insde the cylinder as the stroke moves from TDC to BDC. Swept Volume,  V= pi/4*d^2*L*K   , where                                            d- Bore, L-Stroke,  K-no. of cylinders. This is the common terminology used to specify the engine size. A 1.2L engine means a 1.2 litre engine, which is equal to 1200cc (cc = cubic capacity).  Hope that explains it! Pros/Cons: Usually, hig...
Read more

Difference between a muffler and a catalytic converter

-
Image
A muffler makes the  car  quiet, the cat makes the exhaust clean. Cars built after 1974 originally had both, but it's legal to run with no muffler as long as the car isn't too loud. The cat is required, you can't pass emissions without one. Some people will remove the cat, if they live in a county without  emissions testing , but that is illegal. If you have a car with no  catalytic converter , and the muffler goes bad, sure you could put a cat on instead. They're more expensive, and louder, but that would get you legal. Actually, the cat is supposed to be mounted closer to the engine, where there is more exhaust heat to burn off exhaust crud. I suppose if you wanted to, you could run two catalytic converters. That would greatly restrict your exhaust and cut down on horsepower, probably reduce fuel economy as well. Probably wouldn't help emissions, either. hey are two totally different things,each with it's own  seperate purpose. You could put 2 co...
Read more

Nitrox suspension - Gas charged suspensions

-
Image
The advantages of using a Nitrox suspension - Gas charged suspensions. The rear shock absorbers on current Bajaj Pulsar series bikes are also popularly known as NITROX shock absorbers . These types of shock absorbers are actually called as ‘Gas Filled Shock Absorbers’. The visual differentiation between a conventional shock absorber and a gas filled shock absorber is a small canister (box) which is attached on one side of it. This canister holds a small amount of Nitrogen gas in it. Hence these hydraulic shock absorbers or dampers are called as gas filled shock absorbers. So what is the reason to use a gas filled hydraulic dampers instead of using a conventional one? we'll find out the answer here. The 'Royal Enfield - Bullet Electra' was the first bike in India to have this feature. The Pulsar 150/180 UG II (2’nd upgrade) then became the second model (and the first in the 150 cc and above category) to make this feature available on Indian bikes. A ...
Read more