# What is Adiabatic compression: Definition and 41 Discussions

In thermodynamics, an adiabatic process (from the Greek adiábatos, meaning “impassable”) is a type of thermodynamic process which occurs without transferring heat or mass between the system and its surroundings. Unlike an isothermal process, an adiabatic process transfers energy to the surroundings only as work. It also conceptually supports the theory used to explain the first law of thermodynamics and is therefore a key thermodynamic concept.
Some chemical and physical processes occur too rapidly for energy to enter or leave the system as heat, allowing a convenient "adiabatic approximation". For example, the adiabatic flame temperature uses this approximation to calculate the upper limit of flame temperature by assuming combustion loses no heat to its surroundings.
In meteorology and oceanography, adiabatic cooling produces condensation of moisture or salinity, oversaturating the parcel. Therefore, the excess must be removed. There, the process becomes a pseudo-adiabatic process whereby the liquid water or salt that condenses is assumed to be removed upon formation by idealized instantaneous precipitation. The pseudoadiabatic process is only defined for expansion because a compressed parcel becomes warmer and remains undersaturated.

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1. ### Work done in adiabatic compression

The equation I know for adiabatic work is W = P1V1((V1/V2)ϒ-1 - 1))/ϒ-1, but this involves ϒ, but I can use ϒ = Cp/Cv = Cv+R/Cv = 1 + Cv/R, does this seem correct? But I still have a P1

This is a relatively simple problem, but I'm not getting the right answer. For adiabatic compression, work on gas is positive, since work on gas = ΔEth and the adiabatic process moves from a lower isotherm to a higher one. Integrating for work gives: pV * (Vf(1 - gamma) - Vi(1 -...
3. ### Combustion of an explosive liquid bubble

Problem Statement: An explosive liquid at temperature 300 K contains a spherical bubble of radius 5 mm, full of its vapour. When a mechanical shock to the liquid causes adiabatic compression of the bubble, what radius of the bubble is required for combustion of the vapour, given that the vapour...

Homework Statement Question If changed isothermal compression process to adiabatic compression process. find the final temperature of process. Homework Equations ## \alpha = \frac{1}{v} (\frac{∂v}{∂T})_{P} ## expansivity ## \beta = -\frac{1}{v} (\frac{∂v}{∂P})_{T} ## compressibility...
5. ### Work done in adiabatic process vs work done in isothermal

Homework Statement [/B] An ideal gas is compressed to the same volume from the same initial state for both an adiabatic and an isothermal process. In which case will more work be done ? 2. Homework Equations ##dU=dQ - dW ## ##W=\int P\,dV ##(For isothermal) ##W=nc_vdT##...
6. ### Isothermic and adiabatic compression

Homework Statement Determine the ratio of the work that you must expend when a single-atom ideal Gas once isothermic and once adiabatic to 1/10 of its original volume is compressed. In both cases the initial pressure, initial volume and gas amount are all equal. The Attempt at a Solution Case...
7. ### 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...
8. ### Adiabatic compressed air and energy calculations

Homework Statement . Consider a pump that is required to compress air in a factory. The cylinder in the pump has an inner diameter of 2.00 cm and length 60.0 cm. Air is drawn into the pump at atmospheric pressure and 18 degrees celcius and the pump adiabatically compresses the air to a pressure...
9. ### Temperature in the regulator valve of a cylinder

Homework Statement There is a cylinder of oxygen connected to a valve (A) and then to connected to a regulatory valve. The volume of both valves and the pipes between them is Vr and can be disconsidered in regard to the cylinder's volume. The oxygen can be considered a perfect gas with...
10. ### How much work is done by the Adiabatic Compression of Diatomic Gasses

I apologize if my questions were in the wrong place. I am in "Advanced" Physics Classes. And so I post the questions from those classes in the Advanced Physics forum. And these are questions that weren't covered in Introductory Physics (1st three semesters). But they keep being moved to this...
11. ### What is the volume of the gas after adiabatic compression

Homework Statement 1 liter of ideal diatomic gas (allow for rotation but not vibration) at a pressure of 1 atmosphere and a temperature of 300 K is compressed adiabatically to a pressure of 7 atm. What is the volume of the gas after compression? Homework Equations PV=NKT PV=nRT ##U_T##=f/2*NKT...
12. ### Finding work of adiabatic compressor using ideal gas

Homework Statement Methane at ## P_1 ## and ## T_1 ## is compressed to a pressure of ## P_2 ## adiabatically at steady-state. Calculate the work done on the compressor and the temperature ## T_2 ## of the discharge gas. Use ideal gas model. Given: ## T_1, P_1, P_2, C_p, \gamma = 1.4 ## ##...
13. ### Centrifugal compressors, adiabatic compression

Homework Statement I am working on creating a spreadsheet where you can input the parameters of an engine at a given rotational speed such as volumetric efficiency, boost pressure, atmospheric pressure and temperature, and compressor efficiency... It's been a very long time since I've done...
14. ### Find the change in temperature during adiabatic compression

Homework Statement Homework Equations $$PV^{\gamma}=\mathrm{constant}$$ The Attempt at a Solution Initially, the piston will get a velocity ##v##. But the chamber will move too because of the forces exerted by the gas. Since total external force is zero, velocity of centre of mass is...
15. ### Work Done in Carnot Cycle: Adiabatic Compression

1.what is the work done in an adiabatic compression process in a carnot cycle when we consider work done in efficiency why do we take heat exchange into account i.e.,qs-qr The Attempt at a Solution
16. ### Frustrated with Adiabatic compression problem

Homework Statement In a diesel engine air is adiabatically compressed to autoignition temperature (287oC) of diesel. Given C/nR=2.78 for air, and the room temperature is 27oC, what is the compression ratio where diesel vapor is added for ignition. Homework Equations PV=nRT PV=NkT C=(dU/dT)...
17. ### Thermodynamics - Adiabatic Compression

A monatomic ideal gas that is initially at a pressure of 1.60×105Pa and with a volume of 8.50×10−2m3 is compressed adiabatically to a volume of 4.00×10−2m3 A) What is the final pressure? - 5.63E5 B) How much work is done by the gas during the compression? C) What is the ratio of the...
18. ### Ideal diatomic gas undergoing adiabatic compression

Homework Statement A very simple question, but I can't figure it out. An ideal diatomic gas, with rotation but no oscillation, undergoes an adiabatic compression. Its initial pressure and volume are 1.20 atm and 0.200 m^3. Its final pressure is 3.60 atm. How much work is done by the gas...
19. ### Adiabatic Compression: Pressure & Temperature Change

I am thinking about the adibatic compression when the gas gets back to Th from Tc... My question is how the p and V gets same as the initial pressure and temperature... Can you prove it?
20. ### Isothermal and Adiabatic Compression of a Solid

Homework Statement A 200g cylinder of metallic copper is compressed isothermally and quasi-statically at 290K in a high-pressure cell. A) Find the change in internal energy of the copper when the pressure is increased from 0 to 12kbar. B) How much heat is exchanged with the surrounding fluid...
21. ### Adiabatic compression of ideal diatomic gas

Homework Statement An ideal diatomic gas, with rotation but no oscillation, undergoes an adiabatic compression. Its initial pressure and volume are 1.9 atm and 0.30 m3. It's final pressure is 2.9 atm. How much work is done by the gas? P0 = 1.9 atm = 1.93e5 Pa V0 = 0.30 m3 P = 2.9 atm =...
22. ### Work Required for Adiabatic Compression

Homework Statement One mole of gas compressed to half of its original volume adiabatically, what is the work done? Homework Equations dE= dW + dQ (the d one the w and q should have the line though it) pV^ α= constant = k The Attempt at a Solution As it is adiabatic dQ = 0...
23. ### Ideal Gases under Adiabatic Compression

I'm having trouble understanding what happens to the internal energy of an ideal gas being compressed adiabatically. If DU = DQ + DW, then as we do work PdV compressing the gas, since in adiabatic processes DQ=0, W the change in internal energy is non-zero, so U must increase. But if...
24. ### Reversible Adiabatic Compression: Enthaply Calc

Homework Statement a fluid undergoes a reversible adiabatic compression from .5 MPa, .2 m3 to .05 m3 according to the law PV1.3 = constant. determine the change in enthalpy, internal energy and work transfer during the process. Homework Equations P1V11.3 = P2V21.3 dH = T dS + V dP dS = 0...

Homework Statement http://img29.imageshack.us/img29/4386/prob1p.jpg [Broken] The Attempt at a Solution To answer the first question as to why the air needs to be refrigerated, I think it's because refrigerating the gas cause it to do work, so its enthalpy will decrease resulting in a...
26. ### Adiabatic compression of gas at two temperatures

I have a system that looks like this: The top part is a piston, whereas the bottom is a displacer. I have looked at the Isothermal case for this system in a separate thread (https://www.physicsforums.com/showthread.php?t=553165) But in short, the result was that the pressure of the system...

Hi, I have a little problem understanding adiabatic compression. Let me start with the definition of adiabatic process from wikipedia, "In thermodynamics, an adiabatic process or an isocaloric process is a thermodynamic process in which the net heat transfer to or from the working fluid is...
28. ### Change in entropy for adiabatic compression

Homework Statement A sample of 8.02*10^-1 moles of nitrogen gas (\gamma=1.4) occupies a volume of 2*10^-2m^3 at pressure 1*10^5pa and temperature 300K. The gas is adiabatically compressed to half its original volume. What is the change in entropy of the gas? Homework Equations...

Two moles of a diatomic gas occupies a volume of 50 L and is at a pressure 4atm. The gas then undergoes a process: a reversible adiabatic compression, so that is temperature doubles. Find both temperatures, and find the volume and the pressure after the compression process. my thoughts...
30. ### Adiabatic compression of air

I'd just like to check my answer, it seems too big Homework Statement Air initially at 20◦C is compressed by a factor of 15. What is the final temperature assuming that the compression is adiabatic and \gamma ≈ 1.4 the value of \gamma for air in the relevant range of temperatures? By what...
31. ### Finding internal energy change in a adiabatic compression process.

Can you help me with this problem? An ideal gas is compressed adiabatically. The work done over it is 200 J. How much will the internal energy change? A) 200 J B) 100 J C) -200 J D) 0 J Which formula do you use to solve it? Thanks in advance!
32. ### Adiabatic compression at a constant rate

I came up with this question a while ago, and my Physics teacher and I just can't get the math to work. Here it is: A cylindrical container of base area A and height h holds some number of moles, n, of an ideal gas. One end of the container is movable, and a force F is applied to that...
33. ### Adiabatic Compression - Graphs

Homework Statement Consider an adiabatic chemical reaction which results in the system being compressed. Assume an infinitely large surrounding. Draw a pressure-volume plot for the process. Indicate the points corresponding to your final and initial volumes o the plot. Indicate at which...
34. ### Adiabatic compression of a gas

An explosive liquid at temperature 300 K contains a spherical bubble of radius 5 mm, full of its vapour. When a mechanical shock to the liquid causes adiabatic compression of the bubble, what radius of the bubble is required for combustion of the vapour, given that the vapour ignites...

Homework Statement The engine of a Ferrari F355 F1 sports car takes in air at 20.0 *C and 1.00 atm and compresses it adiabatically to 0.0900 times the original volume. The air may be treated as an ideal gas with \gamma = 1.40. Find Final Temp and Final Pressure Homework Equations...
36. ### Adiabatic compression in a diesel engine

Homework Statement In a diesel engine, atmospheric air is quickly compressed to about 1/20 of its original volume. Estimate the temperature of the air after compression , and explain why a Diesel engine does not require spark plugs. Homework Equations f/2*ln(T_f/T_i)=-ln(V_f/V_i) The...

is equation T2=T1*(p2/p2)^((k-1/k)) correct to calculate air temperatute during compression from 1bar to 2bar in a radial compressor? and equation for temperature drop throug intercoller T3=T2-ICefficiency*(T2-ambient_air_temp). Is this equation really so simple, what about air density when...