Diffuser vs Impeller: Difference and Comparison

Many discoveries have come along as a result of the growth and development of Science and Technology.

Various types of machinery and devices have been invented by engineers and scientist that has become a useful commodity in our life.

Diffuser and Impeller are the two creations that are used in the everyday life that provides us various benefits be it in the form of an air diffuser, aromatherapy, maintaining the force of water in the tank, or for the function of the washing machine this machine makes our work quick and easy.

Key Takeaways

  1. Diffusers are pump components that regulate fluid flow, converting velocity energy into pressure energy.
  2. Impellers are rotating parts within a pump that transfer energy from the motor to the fluid, propelling it through the system.
  3. Diffusers control fluid flow, while impellers are responsible for moving the fluid.

Diffuser vs Impeller

Diffuser is a device that spreads out a fluid or gas to reduce its velocity. Diffusers are used in air handling systems to smooth out the flow of air and reduce turbulence. Impeller is a rotating component that is used to move fluid or gas and increase it’s pressure by generating a swirling motion.

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The Diffuser is a critical component of a compressor or pump. It aims to increase the force by reducing the velocity of the flow leaving the impeller.

The diffuser can be simply described as a non-rotating conduit with increasing flow area in the axis of flow.

A Diffuser uses tiny, permeable particles of beneficial essential oils to permeate the air in a room, creating a tranquil, more comfortable environment.

An Impeller is a propeller-like component of a pump or compressor that spins at a great velocity to increase the flow velocity of a fluid.

Impellers are built of a variety of metals and polymers, including steel, iron, and bronze. As the fluid flows through the pump, the impeller transmits energy to it, increasing the fluid’s speed at the outlet pipe.

Comparison Table

Parameters of ComparisonDiffuserImpeller
PurposeTo improve pumping system performanceRaise the velocity and flow of the liquid
Used in Both all-air and air-water HVAC systems use it.Pumps, agitation tanks, washing machines, etc
Located in In a compressor, the Diffuser is located at the outlet guide vanes where pressurized air enters.Centrifugal pumps
Types1) Nebulizing
3) Heat, and
4) Evaporative diffuser
1)Radial impeller
2)Mixed flow impeller
3)Axial flow impeller
4)Peripheral impeller
Function in a pumpTo boost pressure by decreasing the velocity of the flow while departing from the impellerAccelerate the fluid radially outwards from the center of rotation by transferring energy from the motor to the pump

What is a Diffuser?

A diffuser is defined as “a device for lowering the velocity of a liquid traveling through a system while raising the static pressure.”

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Pressure recovery refers to the rise in the liquid’s static force as it flows through a tube. Fluid velocity reduces as the area grows, whereas static pressure increases.

A Diffuser is a device that causes a decrease in flow velocity and a rise in static pressure while generating the least amount of loss feasible.

In a sealed tube or channel, a diffuser is distinguished by a flow path with a rising cross-sectional area in the direction of flow. Diffusers allow essential oils to permeate throughout a room or even an entire surrounding.

It may be used for aromatherapy, to give the air a fresh perfume, to help you relax, and to help you fight many health problems. There are various benefits of a Diffuser in our everyday life, some of the benefits are listed below:

  • It aids with relaxation.
  • Enhances emotions of serenity.
  • Clarity and focus are improved.
  • It is less difficult to modify one’s lifestyle.
  • It improves your mood.
  • The appearance of redness is reduced.
  • Can help to relieve painful joints.
  • Aids in the clearing of airways for easier breathing.
  • It is also employed in the air drier, cars, medicals which make the work of the people easier and convenient.

What is an Impeller?

Impellers are revolving devices that are used to change the flow and pressure of liquids, gases, and fumes. Impellers are made up of a series of vanes, most of which are blade-shaped, placed around a short central shaft.

Whenever the shaft and vanes revolve, liquids or gases are sucked in and pushed out the other end. Impeller in Pumps: Impellers are used in a variety of pumping equipment, including centrifugal pumps and vacuum pumps.

Bernoulli’s principle, which asserts that a rise in fluid velocity is followed by a drop in pressure or energy stored (and vice versa) is used to regulate pump impellers.

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When liquid or gas reaches an impeller pump, it gets trapped between the impeller vanes and the pump barrier, increasing in velocity as it goes from the impeller eye (center) to the impeller’s outer diameter.

According to Bernoulli’s principle, once the media reaches a specific point near exterior diameter, it abruptly reduces in velocity and receives an equal increase in pressure.

As the media is released from the impeller and out of the pump opening, it becomes progressively more pressured.

According to the principles of operation, it can be deduced that a pump’s output pressure and flow are mostly determined by the impeller’s rotating speed (which influences velocity) and vane height (which influences pressure and the possibility of forming a vacuum).

Impellers come in three designs, which are as follows:

1) Open Design: Open impellers are made up of a series of vanes connected to a central “hub” that can be coupled to a shaft.

2) Closed Design: Two solid plates are fastened to both sides of the blades in a closed impeller.


Main Difference Between Diffuser and Impeller

1. Diffuser was invented in the year 1937, while Impeller was invented in the year 1772.

2) A Diffuser is a non-rotating channel in a pump while an Impeller is  a rotating iron that has vanes.

3) A diffuser reduces the velocity of fluid while raising the static pressure whereas, Impeller rises the fluid’s velocity and pressure.

4) The average life span of a diffuser is 4000 hours, while that of Impeller is 300 hours.

5) Delhi, Ahmedabad, Nagpur, etc are the states in India where Diffusers are manufactured while Maharashtra, Pune, Nashik are the states in India where Impellers are manufactured.

  1. https://asmedigitalcollection.asme.org/turbomachinery/article-abstract/125/1/173/446146
  2. https://asmedigitalcollection.asme.org/fluidsengineering/article-abstract/123/3/466/452487

Last Updated : 21 July, 2023

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