Main types of compressors used in industrial refrigeration are screw, piston, centrifugal and rotary vane. Suitable for continuous compressed air supply, such as cooling unit. Sorokes dresserrand selecting a centrifugal compressor inlet pressure p1 temperature t1. Turbomachinery aerodynamics online course video lectures. Surging is a momentary back flow through the compressor from the discharge to the suction.
Multistage compressor are also considered to have beamtype design but the impellers are located between the radial bearings. An aerofoil stalls when the air flow completely separates from the top side or su. Centrifugal pumps are commonly used to move liquids through a piping system. Positive displacement compressors cab be further divided into reciprocating and rotary compressors. To understand the concept behind stalling and surging, we should first know the flow over an airfoil. Centrifugal compressors produce highpressure discharge by converting angular momentum imparted by the rotating impeller dynamic displacement. Present the analysis of centrifugal compressors section 21.
Airfoil data and profile construction 3d blade shapes centrifugal compressors and radial flow turbines. As specific speed increases, bhp at shutoff tends to rise. If you are new to the compressor, this article will definitely make yourself familiar with the centrifugal compressor performance curve. Axial compressors are rotating, aerofoil based compressors in which the working fluid principally flows parallel to the axis of rotation. It is the volume of air delivered by the compressor, and is expressed in m3min or m 3s. As specific speed incresaes, head at shutoff tends to rise relative to head within the aor.
Lower energy cost, small size suitable for continuous operation 247, low efficiency. Hello and welcome to lecture number nineteen of this lecture series on jet aircraft propulsion. Jacques chaurettes excellent article centrifugal pump specific speed primer and the affinity laws provides a great deal more detail on this topic. If you already know about the centrifugal compressor performance curve, definitely this article will refresh your knowledge. By harmonizing these technical requirements into a single set of. Centrifugal compressors can develop higher per stage pressure ratios. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially. Surging and stalling both lead to unstable flow in compressors. Design calculation of blade design for axial flow compressor an axial flow compressor used in gas turbine engine has constant axial velocity throughout the compressor of 152 ms, blade mean velocity of 162 ms and it is delivered 10. Som,department of mechanical engineering,iit kharagpur. What is surging and choking in centrifugal compressor.
Iit kharagpur notes converted into high quality audio source nptel. Lecture series on steam and gas power systems by prof. You are told to purchase a pump for your manufacturing facility that will carry water to the top of a tower at your facility. How to read a centrifugal compressor performance curve. Types of fans axial and propeller fans, centrifugal radial fans, mixed flow fans and cross flow fans. This is in contrast with centrifugal, axi centrifugal and mixedflow compressors where the air may enter axi. Centrifugal compressors also known as turbocompressors are radial flow. Pradeep, department of aerospace engineering, iit bombay. Multistage compressor can be arranged in straightthrough, compound, and double flow configurations. Hello and welcome to lecture number thirtytwo of this lecture series on turbomachinery. Specific work done by turbo machines pumps, compressors and fans specific work from pumps, fans, compressors and turbines. Throughout each and every stage the temperature and the compression ratio are assumed to be constant.
The centrifugal air compressor is an oil free compressor by design. Read here to know about various types of air compressors used and get a clear inside view of each type of compressor with the attached pictures. Unit 7 air compressors working of a single stage reciprocating air compressor, calculation of work input, volumetric efficiency, isothermal efficiency, advantages of multi stage compression, two stage compressor with. Surge is a characteristic behaviour of a centrifugal compressor that can occur when inlet flow is reduced such that the head developed by the compressor is insufficient to overcome the pressure at the discharge of the compressor. A 150hp compressor runs 90% loaded 12 hours per day 5 days per week at a delivery pressure of 110psi. What are the disadvantages and advantages of axial and. Hello and welcome to lecture number thirtyone of this lecture series on turbomachinery. This can occur when the mass flow of gas to the compressor falls below a critical level with a high pressure difference. The oil lubricated running gear is separated from the air by shaft seals and atmospheric vents. Understand your process, as well as the advantages and disadvantages of each centrifugal compressor configuration, in order to choose the optimal centrifugal compressor for your application. Citations 0 references 15 researchgate has not been able to resolve any citations for this publication. Compressor, device for increasing the pressure of a gas by mechanically decreasing its volume.
Centrifugal compressors also suffer from instability problems like surge and rotating stall. Manual purpose to be used for selection, application into the system, power and cooling water estimation. Advantages of centrifugal compressor low weight, easy to design and manufacture. Unlike displacement compressors that work at a constant flow, dynamic compressors work at a constant pressure and the performance is affected by external conditions such as changes in inlet temperatures. Basic aerothermodynamics of centrifugal compressors. Types of air compressors reciprocating, rotary screw and rotary centrifugal air compressors. The centrifugal is a continuous duty compressor, with few moving parts, that is particularly suited to high volume.
Compressors are work absorbing devices which are used for increasing pressure of fluid at the expense of work done on fluid. The three general types of compressors are positive displacement, centrifugal. The device studied is here is a compressor with compression ratio 2. Pump sizing and selection made easy chemical engineering. A centrifugal compressor is a type of dynamic compressor, or turbocompressor, with a radial design. The compressors used for compressing air are called air. A positive vane angle produces prewhirl in the direction of impeller rotations and a negative vane angle produces prewhirl in the opposite dire. Another type, which is produced in large quantities, a scroll compressor, but still these compressors are not available in the amount normally encountered in industrial refrigeration. The information provided in this document is given in good faith, but alfa laval is not able to accept any responsibility for the accuracy of its content, or any consequences that may arise from the use of the information supplied or materials described. Centrifugal compressor 1 mechanical engineering in. Jet engine cutaway showing the centrifugal compressor and other parts. The design process starts with the aerodynamic analysis of the preliminary design and its. Jet aircraft propulsion online course video lectures by.
To find a simple analytical model for centrifugal compressors in turbochargers why. Centrifugal compressor is widely used in chemical and petroleum refinery industry for specifies services. The centrifugal air compressor is a dynamic compressor which depends on transfer of energy from a rotating impeller to the air. Discuss the selection of impeller diameter and speed of a centrifugal compressor using velocity. What is the difference between axial flow compressor and. The physics of centrifugal compressor perfromance, considering aerodynamics and thermodynamics, especially for real gases. This paper investigates the development of a preliminary design method for centrifugal compressors. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. In 20, 35 million vehicles licensed for use in great britain alone in 2012, total co 2 emissions from cars in uk was 63 million tonnes improvements to turbochargers leads to more fuel efficient cars. Ejector quiet operation high volume of air, steady flow. This manual does not for designing centrifugal compressor and those parts. Introduction to fluid machines and compressible flow by prof. Section 3 description of surge 31 surge versus stall surge is a dynamic instability that occurs in dynamic compressors.
Centrifugal compressor characteristics amp 1 surging, chocking, rotating stall sources of centrifugal compressor losses design of centrifugal compressors br 2 design of impellers design of subsonic and supersonic vaned diffusers, vaneless volutes radial turbine br 2 introduction thermodynamics and aerodynamics of radial turbines radial turbine. Introduction elements of centrifugal compressor fan inlet duct and guide vane, impeller, diffuser vanes and vaneless diffusers slip. Introduction to fluid machinery turbines, pumps, blowers and compressors fluid machines machines are energy conversion devices are called turbomachinery which transfers energy between a fluid system and its mechanical system e. Rotary vane compressors are still used as a low stage compressors, but very little installed. Air is the most frequently compressed gas but natural gas, oxygen, nitrogen, and other industrially important gases are also compressed. Pdf control concepts for centrifugal compressor applications. Introduction to fluid machinery turbines, pumps, blowers. Special university course for future engineers lecture notes. It seems that the only requirement for building such compressor is to design the wheel in such a way to induce an outlet tangential velocity equal to 90% of the rotor speed and to design the di user to convert kinetic energy into pressure. In the article, we will discuss how to read a centrifugal compressor performance curve. Estimate the energy and cost savings if the pressure is reduced to.
The following is a pump sizing problem to illustrate the calculations in this article. Prewhirl is produced by giving the incoming air a whirl component through the use of inlet guide vanes. Lecture notes on turbomachinery mechanical engineering. Nptel syllabus jet aircraft propulsion video course course outline introduction to aircraft jet propulsion. Increased aerodynamic efficiency elliott uses stateoftheart interactive design.
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