What is Compressor: Definition and 199 Discussions

A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor.
Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas. Liquids are relatively incompressible; while some can be compressed, the main action of a pump is to pressurize and transport liquids.
Many compressors can be staged, that is, the fluid is compressed several times in steps or stages, to increase discharge pressure. Often, the second stage is physically smaller than the primary stage, to accommodate the already compressed gas without reducing its pressure. Each stage further compresses the gas and increases its pressure and also temperature (if intercooling between stages is not used).

View More On Wikipedia.org
  1. G

    Compressor driven by an electromagnet

    Figures: Attempt at a Solution: $$L=0,015\, \textrm{m}\qquad R_2=0,01\, \textrm{m}$$ $$R_1-R_2=R_D=0,0075\, \textrm{m}$$ $$L=0,04$$ $$\rho_1=\dfrac{p_1}{R^2T_1}=\dfrac{p_1\bar{M}}{RT_1}=1,164\, \textrm{kg}/\textrm{m}^3$$ Calculate total volume ##V_A+V_B##: $$V_B=\pi \cdot R_2^2\cdot...
  2. H

    MATLAB Modelling a Heat Pump with Linear Compressor using MATLAB Simulink

    Hello, I am a final year mechanical engineering student designing a heat pump with a linear compressor for an electric vehicle and have decided to model this using Simulink, I would love some help on the governing equations/formulas needed for each component of the heat pump as well as guidance...
  3. H

    Why do we need stators in compressors or turbines?

    Hey Everybody! I was wondering why do we need Stators in compressors and turbine, for instance the goal of compressor is to increase the outlet pressure, so that the combustion is effective, but why we don't put just Rotors and no stators in the compressor (or Turbine).
  4. mastermechanic

    Measuring the total pressure of a centrifugal compressor

    Hello everyone, Nowadays I am planning to redesign my centrifugal compressor which I designed for a subsystem in my graduation project. It's a 3D printed and brushless motor driven centrifugal compressor and its about a hand size. However, due to its relatively small size and relatively low RPM...
  5. S

    How pressure increases in centrifugal compressor?

    I have read this in my textbook about principles of operation of centrifugal compressor: "The impeller is rotated at high speed by the turbine and air is continuously induced into the center of the impeller. Centrifugal action causes it to flow radially outwards along the vanes to the impeller...
  6. M

    Heat pump efficiency calculations - Compressor power issue

    The heat pump comprises of the 4 components: evaporator, compressor, condenser and expansion valve. Thermal power required to heat the building: 12.1 kW at condensing temperature tc = 44.3 deg C For the evaporator: vaporizing temperature tv = -7 deg C Subcooling temperature for the heat pump Δ...
  7. bardia sepehrnia

    Engineering Isentropic Efficiency of a Compressor

    We know that if potential and kinetic energy our negligible, the isentropic efficiency of a compressor is isentropic enthalpy change divided by actual enthalpy change: n=(h2s-h1)/(h2a-h1) So I already answered this question and here is the answer: n1 is the isentropic efficiency of the...
  8. M

    Specific work done by an adiabatic & reversible compressor on air

    Hi, A quick question on a conundrum I seem to have encountered. My main question is: why is it wrong to use the formula above instead of the SFEE approach? My approach: Use the formula: $$ w = \frac{R}{1-n} (T_2 - T_1) $$ From the data book, ## R = 0.287 ## kJ/kg K and ## n = \gamma = 1.4 ##...
  9. S

    Peak Amps of a heat pump based AC vs compressor based AC?

    In my city (USA) typical older houses have "100 Amp service" so their peak electric usage is limited to 100 Amps. In considering what sort of electric air conditioning system to install in such a house, peak usage is major consideration. Generally speaking, which type of residential unit...
  10. V

    The power of a multistage compressor

    is there any equation to find the work done, power and efficiency of a multistage compressor with a summation of calculating the power as so, instead of calculating individual power and summing at the end. any citiations is also good to know. thanking you, with regards, vishnuvardhan
  11. V

    Mathematical modeling of a screw compressor

    I am trying to design a compressor in simulink. the mathematical equations has been modeled. but i just need, is there any relation to find the rate of change of volume with respect to time in compressor. Are there any equations or relations to find the rate of change in volume. As its a...
  12. Zifan Wang

    Ideal Gas Law: Question about a compressor exam question

    This is a question in my midterm. I calculated for the answer as c) 11.7 atm by the Ideal Gas Law. The professor states that "all the air is originally at 1 atm" in the prompt indicates an idea of "both 70 L of air and existing 6 L of air in the tank are at 1 atm", and he grades d) 12.7 atm as...
  13. R

    Automotive Can I have a multi-stage reciprocating compressor?

    Hello, This is an enquiry about a multi-stage, reciprocating air compressor. Imagine, there are 6 piston-cylinder-pair combination (numbered (P1, C1)...to (P6, C6) from the left); adjacent to each other. The arrangement is very similar to a 6-Cylinder internal combustion engine. Now, the...
  14. A

    Compound lever arm - compressor design

    So what comes to mind is utilising the full height and further node points in a triangulated system... however being only just now introduced to the concept of a compound lever I am unsure of how to get this system to work. Any thoughts much appreciated.
  15. M

    Overvoltage on the power supply to compressor motors

    Hope you may help me to understand how detrimental to compressor motor would be if it operated at voltages exceeding the manufacturer's specified 400V by 12%? so 448V. I have vendor engineers saying since it exceeds 10% they cannot safely run the plant and of course the voltage monitoring relay...
  16. L

    Is Drying Air Before a Compressor the Best Way to Limit Water Vapor?

    Hi, I was wondering if a dryer is ever placed before the compressor? For limiting the presence of water vapor before the compressor inlet, I was thinking of drying the air before the compressor (it's a closed system btw). Is this the right technique? Or you this be done otherwise? Limiting the...
  17. L

    Lifetime of an oil filter compressor

    Hi,I'm doing an internship about mechanical maintenance. I have come to a problem that is a bit over my head. The problem was also discussed by a few process engineers but they did not come with a good solution. So, the oil filter is part of a biogas compressor. The biogas comes from the...
  18. Anand Sivaram

    About Inverter Compressor: Starting Current

    If we would like to go completely off-grid with a Solar inverter: Normal refrigerators use induction motors for compressors and these induction motors do require around 5x starting current. So, if we use a refrigerator with rated power of 200W, we would require an inverter/power supply rating...
  19. V

    Use only a powerful fan without a compressor?

    Hello & Thanks, Is it possible to use only a powerful fan without a compressor to make very cold air ? Thanks
  20. O

    Auto/Motor Centrifugal compressor lift aircraft -- engineering help please

    Hello, I have a design for a different type of aircraft. I wanted an actual engineer to give advice before I fork over for some parts to try and make a working model. Attached are some pics. some of the pics are as if it were a full size acft. But for the model I was just going to use two turbo...
  21. D

    Air Compressor Model Analysis

    I have an interest in storing, for later use, energy from excess shaft power developed by a wind turbine. Currently I am assuming that the compressor is running in a steady fashion, continually drawing 300K, 1.0 atm. air into the compression chamber and compressing it to 20 atms. before...
  22. R

    Compressor work and Thermodynamics

    how can we use Cp.dT to evaluate compressor work even when one side (inlet side) is having different pressure than other side (outlet side). Cp should be used for constant pressure!
  23. S

    Pressurizing Argon Gas: Pump or Compressor Options?

    I need to pressurized argon gas from 1 bar pressure to 2 bar pressure. Flow rate outlet is 0.5 LPM. Can anybody suggest me a pump or compressor which is small in size? Minitiarised diaphragm seems good option but is it right one?
  24. JME23

    Cooling System-What is the main purpose of the Compressor

    Hi There, Can anyone please help with the attached diagram of a cooling system? In particular the role of the compressor. I understand what happens at each stage but I am keen to understand why. The Hot Airflow passes the Flow Control Valve and some passes through the Primary Heat Exchanger...
  25. B

    Thermodynamics Compressor Work (1st law question)

    Homework Statement Compare the compressor work input required to compress water isentropically from 100kpa to 1MPa, assuming that the water exists as (a) saturated liquid and (b) saturated vapor at the inlet state Homework Equations Win = v(P2-P1) Win = (h2- h1) The Attempt at a Solution...
  26. D

    How does air behave in the daisy chaining of compressors?

    I'm working on a project involving compressing air to a desired high pressure. So far the only equation I've been paying attention to is the ideal gas law. My question is if an air compressor pump is rated to create a maximum pressure of 100 psi based on its inlet being at atmospheric pressure...
  27. S

    Pressure trace of a tank fed by a compressor

    G'Day All, This is my first post so please let me know if I have completed this form incorrectly, or missed a point of etiquette etc... 1. Homework Statement The problem is to determine the pressurisation rate of a tank being filled by a pipe connected to a compressor. Assumptions: Pipe...
  28. runningman19

    Adiabatic Compressor: Ideal Gas Temperature Change

    Homework Statement A mixture of hydrogen, carbon monoxide and carbon dioxide is being fed to a compressor at 2.0 bar and 25 C. The overall flow rate is 17.47 SCMS and its composition is 73.5 mol% H2, 13.7 mol% CO and the balance CO2 The compressor operates adiabatically and reversibly with a...
  29. T

    Compressing a gas above compressor's discharge pressure

    A 2 stage compressor has a final delivery/discharge pressure of 250 bar. hydrogen is been compressed and stored in vessels. The pressure in the storage vessel reaches the delivery pressure(i.e.250 bar) and the compressor is still running ( vessel has a safety pressure of 450 bar) and the...
  30. MCTachyon

    Calc Volumetric Flow Rate of Free Air: 0.841 m3/s

    Homework Statement Air is to be compressed from a pressure of 1 bar and a temperature of 20°C to a pressure of 15 bar in a two stage compressor with intercooling. After intercooling the air temperature returns to 20°C and the polytropic index of compression is 1.28. If the input power per...
  31. B

    How to make a simple mini compressor for small needs

    How to make simple mini compressor for small needs There are many cases where we need lớn use air compressors but not available. In other cases, they want to use air compressors but are afraid lớn buy because of less use. In this case the simplest option would be lớn make your own compressor. We...
  32. R

    Simple home-made hydrogene compressor

    I would like to buy or build a small hydrogen compressor to fill a little 5L tank after electrolysis (releasing oxygen free to the air, just compress H to 200-300 PSI). All looks fairly doable except for the compressor priced at $20K+. I thought to get it for a small fraction of that price and...
  33. T

    Calculate uncertainty in pressure, temperature and time?

    Homework Statement [/B] After doing a lab on air compressors, we were asked to calculate Error in Pressure, Temperature and time measurements taken (all at 30 second intervals). We took pressure and temperature values at time = 0,30,60,90,120,150 and 180 seconds. We repeated the experiment 5...
  34. M

    What is the use of a butterfly valve in axial compressor

    Homework Statement In the image I have included it shows a diagram of the setup we used in a lab and you can see that at the right hand side there is a butterfly valve so I am wandering what would be the use of the valve in this situation. Since its after the compressor I was thinking that its...
  35. M

    Behaviour of an axial flow compressor with a butterfly valve

    Homework Statement I just did a lab experiment that involved recording the heights of manometer tubes placed in different locations along the compressor in order to calculate pressure drops, air mass flow rate, isentropic efficiency. An electric motor provided the power to drive the compressor...
  36. M

    Calculating isentropic efficiency of a compressor

    Homework Statement We did an experiment which included having an electric motor provide power to drive the compressor and we had instrumentation available to measure the compressor shaft torque and shaft rotational speed and 6 water filled manometer tubes were used as measurements of the...
  37. M

    Interpreting graphs from isentropic efficiency of a compressor lab

    Homework Statement We did a lab experiment for isentropic efficiency of a compressor and was asked to plot the following graphs, change in stagnation pressure across the compressor (∆p0) vs air mass flow rate, and isentropic efficiency vs air mass flow rate. I have plotted the graphs but not...
  38. Shariq Qazi

    Air Compressor Pressure vs CFM vs SCFM

    So my boss hook me up with the Compressed Air Calculations which we never did previously at our workplace. So started researching about the subject and designed a Compressed air system. The only thing i am not sure about now here is the relation between CFM vs SCFM vs Pressure. Let us take an...
  39. C

    Centrifugal compressor with relief valve formulas

    Hi folks, I have a question regarding centrifugal compressors when a relief valve is included in the system. Allow me to explain... There is a centrifugal compressor supplying air to an aircraft engine. As altitude varies, the compressor provides enough pressure up to altitude "X" for the...
  40. Vikramaditya

    Lifting a car of 1500 Kg through air compressor

    If I want to lift a car of 1500 kg with a air compressor and with 50 nozzles, what should be the size of nozzles and what should be the pressure of air compressor and at what pressure will the air come out through nose so that it could be easily be lifted.
  41. R

    Compressor Problem in thermodynamics

    Hello, I am working on the following problem: Homework Statement -------------------------------------------------------------------------------------- During the modifications in the process you are working on, your direct boss is interest in replacing a few equipment for new ones in order to...
  42. yangshi

    Low Air Compressor CFM Still Works?

    Halfway through my thesis on a mach 2 ramjet, and I unfortunately realize that I need 50-72 CFM to test it. The only ACs I have are 2 CFM portable pancakes. Is it possible to run say a 25 CFM AC at 50 CFM for a short period of 10-60 seconds? Is there a quantitative way to find how long the AC...
  43. marcophys

    Calc L/min air compression to different pressures & temps in my compressor

    I have acquired a new compressor rated at 540 L/min @ 7 bar 150L tank I decided to test this at 23 degC, timing compression at 2 bar intervals (0-2, 2-4 etc.) I was surprised to find that it maintained 34 seconds at each interval up to 8 bar (but this could be poor experimental...
  44. S

    Understand Power Required for Screw Air Compressor

    Could someone help me with getting an understanding of the equations for the power required to compress screw air please.
  45. M

    Electrical Power required to drive a DIY electromagnetic air compressor

    I'm trying to calculate the battery requirements for an experimental home built air compressor. I understand that electromagnetic air compressors operate using attraction and repulsion forces created by electromagnets using the basic magnetic principle that like poles of two magnets repel and...
  46. cyberdiver

    Using electrochemical hydrogen compressor in reverse

    Electrochemical hydrogen compressors (https://en.wikipedia.org/wiki/Electrochemical_hydrogen_compressor) basically convert an electrical potential difference into a pressure difference. Would it be possible to run one of these in reverse, i.e. using a pressure difference to create a voltage? If...
  47. G

    220V 50Hz Equipment vs. 230V 60Hz Equipment compressor

    If If you have a compressor designed for US 60 HZ 230 V what are the risks with applying it in 220 V 50 HZ ? I understand there will be a ~20% derate in power but are there any safety or failure concerns ? would the lifespan of equipment change? Do I need a transformer ? This equipment...
  48. O

    Compressor Relation: Torque, Speed & Efficiency

    Hi everyone! I am new to mechanical engineering and recently I started about compressors. I am trying to find relation between torque, speed and output efficiency of the compressor. Can anyone help me with simple explanation so that I can understand. I will be really thankful if you could help...
  49. P

    Commercial thermoacoustic compressor manufacturer

    Thermoacoustic compression i.e. compression using interference phenomenon of sound waves has been under research for quite a long time. I want to know whether it has been commercialized or not. I mean whether I find any company that manufactures and sells thermoacoustic compressor in market or...
  50. P

    Need help to find a steam compressor

    At present, I am looking for a steam compressor or steam compressor system that can compress very low pressure steam (2.56 kPa) to 1 bar and above. I know well that such high compression ratio will be impossible for a single set to achieve, therefore it more than one sets have to set in series...