- 1 Introduction:
- 2 Dynamic Compressor Working Principle
- 3 Dynamic Compressor types:
- 4 Components of Dynamic Compressor:
- 5 Advantages and Disadvantages of Dynamic Displacement Compressors:
- 6 Applications of Dynamic Compressor
The main objective is to explain the dynamic compressor working principle and different dynamic compressor types. A dynamic displacement compressor is a famous type of air compressor. Generally, the main feature of this type of compressor is that it contains blades that rotate at high speed. In dynamic displacement compressors, the air sucks in between the impeller rotating blades and increases the velocity of the air. Finally, the gas or air discharges from the diffuser that converts the kinetic energy of the air or gas into pressure energy.
Mostly, these types of air compressors act as turbochargers with a radial or axial gas flow pattern. Actually, these compressors usually design for high gas flow rates.
Dynamic displacement compressors work at constant pressure, while positive displacement compressors work at a constant gas flow rate while pressure changes during the working. A positive displacement compressor compresses gas using a piston, while the dynamic displacement compressor uses a diffuser for air compression. As compare to other types of compressors, dynamic compressors are more reliable. The most important thing is that it is straightforward to design.
Dynamic displacement compressors are more reliable than other compressors because there are no alternative components that are subject to repeated loads during use. These compressors also represent turbochargers because they can generate enormous horsepower. These types of compressors typically use in large operations.
Also read: How Positive diplacement compressor work?
Dynamic Compressor Working Principle
The dynamic displacement compressor working principle is based on thermodynamics principles. First of all, air introduces through the inlet of the compressor into the chamber. When the air passes between the blades of the impeller, the impeller blades provide kinetic energy to the air. In this way, the velocity of the air increases.
A diffuser connects with the compressor. This diffuser converts the velocity of the air into pressure. After that, the air discharges through the outlet of the dynamic compressor. These compressors have a narrow range of operation and are suitable for particular operating conditions.
Dynamic Compressor types:
The primary dynamic compressor types are given below.
1) Centrifugal Compressors:
Main Article: Centrifugal Compressor
Centrifugal compressor includes in the most famous dynamic compressor types. This compressor performs a compression process by applying an inertial force (turning, deceleration, and acceleration) to the gas through a rotating impeller.
In the case of this compressor, the air draw into the impeller center and then accelerate centrifugally toward its circumference. When the diffuser compresses to this air, it will scroll there. There it slows down, and the pressure increases. Mostly these dynamic compressor types use 2 or 3 phases for compression.
Overall, the full load efficiency is good (compared to the lubricated compressor). So, the centrifugal compressor has high maximum load efficiency as compare to other oil-free compressor designs. However, performance will change significantly due to changes in the conditions of the inlet. High humidity, low air pressure, and heat affect almost all compressors, but centrifugation has a more significant effect.
2) Axial Flow Compressor:
Main Article: Axial Flow Compressor
Axial flow compressor is another primary type of dynamic compressor. Thus, it can handle large flow rates of the air is relatively small housing and has sufficient power requirements. The pressure range of these compressors is low to moderate.
The axial compressor uses a series of blades that look like jet engines to force air into smaller and smaller areas. These dynamic displacement compressor types do not widely deplete in the industry. Generally, the axial compressor is lighter and smaller than a comparable centrifugal compressor and typically runs faster.
Mostly, it uses for large and constant gas flow at relatively moderate pressures, for example, in a ventilation system. Its high speed makes it ideal for connecting a gas turbine to generate electricity and propel aircraft. Therefore, these compressors design for high reliability, high efficiency, and high capacity purposes. The axial compressor’s most common applications are blast furnaces, wind tunnels, wastewater treatment, and air separation. Nowadays it is using in Aero-planes.
3) Turbo-Expander Compressors:
This compressor type also includes in the famous dynamic compressor type—a turboexpander, also known as an expansion turbine. An axial or centrifugal turbine expands gas under high pressure to generate work to drive the compressor.
As shown in the figure, the term “turboexpander” is commonly used to define an expander/compressor as a unit. Mostly, it consists of two main parts. The radial compressor (booster) and the radial intake expansion are integrated with one component. The wheel connects to a single axle. The expansion turbine is the engine, and the compressor is the powered unit.
In a natural gas upgrading plant, the purpose of the turbo-expand purpose is to effectively perform two different but complementary functions in a single machine. Its principal function is to generate cooling in the process of gas flow efficiently.
Components of Dynamic Compressor:
The major components of the dynamic compressor are given below.
Usually, the inlet of the dynamic compressor is a simple pipe. However, the operating range of the compressor can also expand by setting the charge line to a lower mass flow rate. Also, the intake guide vane installs in water for pre-swirling.
The rotating impeller blades gradually transfer kinetic energy to the working fluid. The impeller output speed can reach supersonic speeds. So, the type of compressor impeller depends on the angle of the outlet blades.
It collects the flow by rotating it circumferentially and directs it to the outlet pipe of the compressor. The flow velocity in the flow path is further reduced, and the static pressure increases. The volute can take on various geometric shapes. The ideal process for a compressor is a uniform entropy compression without heat exchange with the environment.
4) Radial diffuser:
The diffuser transforms the kinetic energy of the working fluid into pressure energy. This is achieved by gradually decreasing the flow rate and increasing the cross-sectional area. Depending on the application, the diffuser can be without a leaf or with a leaf.
Advantages and Disadvantages of Dynamic Displacement Compressors:
- This type of compressor is more reliable as compared to other types.
- It works with various water flow.
- Mostly, it uses on a large scale.
- Easy to design.
- These have a low weight.
- It requires less maintenance.
- It is an oil-free in nature.
- Less efficient than a positive displacement compressor.
- Dynamic displacement compressors do not compress gas by decreasing the volume, which is the most common method.
- These compressors use one or more rotating elements to accelerate the air and then reduce its velocity.
- Choke, stall, and Surge issues.
- Not suitable for very high compression.
- Sensitive to changes in gas composition.
Applications of Dynamic Compressor
- A type of dynamic compressor uses in refrigeration applications.
- These use for gas injection.
- These compressors also use for compression in gas powerplant.
- A type of dynamic displacement compressor (Axial compressor) uses in Aero-plane.
- Pipeline compression.
This article takes an in-depth look at the dynamic compressor working principle and clears some other concepts. So, if you need more knowledge about this topic, let me know without any hesitation. I will try my best to give you a satisfactory answer.