What is Adiabatic: Definition and 494 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.

View More On Wikipedia.org
Recent contents Top users
  1. R

    Adiabatic compression of an ideal gas

    An ideal gas at a temperature of 17.7°C is compressed adiabatically from an initial volume 70.0 l to a final volume 43.0 l. Find its final temperature (in °C) if CV = 2.50R. so T1V1^g=T2V2^g to find g=cp/cv=(cv+nR)/cv and cv=2.50R g=(2.50R+nR)/2.50R factor out an R...
  2. G

    How to Solve for the Fractional Change in Temperature in an Adiabatic Process?

    Homework Statement 3.14 (0.5) How is the fractional change in temperature related to \frac{dT}{T} the fractional change in pressure \frac{dP}{P} ? (IPhO 2006) Homework Equations PV^{\gamma}=\rm constant The Attempt at a Solution nC_vdT=-PdV (1), dV/dP=-nRT/(P^2) If I...
  3. M

    Is a Fully Adiabatic Process Truly Possible?

    fully adiabatic process? :confused: by definition i know that adiabatic process is a thermodynamic process in which there is no heat transfer and it the same time i also know that nothing is frictionless even though we sometimes assume thing to be. so therefore there will be always heat...
  4. M

    Isothermal or adiabatic process

    :confused: :confused: i was reading my lecture note over the half term but i am still a bit confused and i was wondering if someone could describe in detail, using a p-v diagram, a well known engineering cycle which specifies a isothermal or adiabatic process. Thanks you very much
  5. Amith2006

    What Does V Represent in the Adiabatic Demagnetization Formula?

    Homework Statement The expression for fall in temperature during adiabatic demagnetization is given by, dT = [(CV)/(C(B)T)][(B(i)^2 - B(f)^2)/2] where C = Curie constant, C(B) = Specific heat per unit volume at constant field, T = Temperature, B(i) and B(f) are the initial and...
  6. Amith2006

    Work done in an adiabatic process and isothermals

    Homework Statement It is said that the work done between 2 isothermals is independent of the adiabatic. Homework Equations The work done during an adiabatic process is given by, W = C(v){T1 – T2) The Attempt at a Solution From the above equation it is clear...
  7. S

    Conditions are adiabatic and reversible about a turbine

    Why is it when the conditions are adiabatic and reversible about a turbine, the assumption is its isentropic?
  8. B

    Calculate Entropy Change for Adiabatic Process of Argon Gas

    I have tried every combination of terms that I can think of within PV=nRT to find nR. Here are the three expressions that I have come up with, none of which are correct based on the answer to this question... nR = 100 * 0.01e-3 / 300 (the expression with kPa as the units of pressure) nR...
  9. Repetit

    Work done in adiabatic quasistatic compression

    Hey! "Calculate the work done on 1 mole of a perfect gas in an adiabatic quasistatic compression from volume V1 to V2." The work done on the gas in this compression is: -\int_{V1}^{V2} P dV Because we are talking about an ideal gas the ideal gas law applies so...
  10. M

    Adiabatic heat exchanger problem

    Adiabatic heat exchanger problem... Please Help! I have this proplem as a homework assignment and I'm a bit stuck as houw to set it up. Here it is: Propane gas enters a continuous adiabatic heat exchanger at 40 degrees C and 250 kPa and exits at 240 degrees C. Superheated steam at 300...
  11. O

    Adiabatic cooling vs. Joule-Thomson effect

    When a valve on a pneumatic tire (filled with compressed air) is released and the tire is allowed to deflate, one may notice that the valve stem will become quite cold during the process. A common, everyday observation. So far, so good. The question is: What would we observe if the tire being...
  12. S

    Adiabatic Processes (cylinder)

    An insulated cylinder of cross-sectional area .010m2 contains a monatomic ideal gas at T= 280 K. The system is in a vacuum chamber. Initally the gas supports the piston at a height of .20m. Sand is slowly placed onto the piston. When 10 kg of sand has been added, the piston has fallen .05m. How...
  13. K

    Adiabatic process btwn 2 containers

    Two cylinders of equal volume are connected by a valve. We are given the pressure for one of them, and then told to find the final equilibrium pressure after the valve is opened. Adiabatic process may be assumed. I know the solution, but not sure why its that way... initially, I tried...
  14. C

    Adiabatic, isothermal, or isovolumetric

    Here's my problem: 300 calories of heat are added to a gas as the internal energy of the gas increases by 500 calories. The described thermodynamic process is best described as? My guess is that the process is isothermal b/c work is being done in the system.
  15. J

    Adiabatic process for water

    I was just wondering if there is a relationship between Pressure, Temperature , and Volume like there is for Ideal Gases, but for water. ie. for Ideal Gas: TV^(gamma-1) = constant PV^gamma = constant Any insight would be greatly appreciated, Thanks in advance.
  16. P

    How do you calculate the work done in an adiabatic process?

    How do you calculate the work done in an adiabatic process? I know change in thermal energy = work done. which amounts to (f/2)Nk(change in T). But how do you get change in T? Or is there another way to compute the work directly. The trouble is both the volume and temperture vary during...
  17. B

    Adiabatic Processes and Ideal Gases

    Hey. Im doing this question where Air (said to be ideal gas) is compressed from a pressure of 0.1 MPa and Temp 300K to pressure .5 MPa and temperature 480K. We are supposed to determine whether the process is possible to do adiabatically (sorry if that is the wrong spelling). I hadnt done...
  18. J

    Adiabatic evolution of eigenvalues

    If I have two positive definite Hermitian NxN matrices A and B, if I adiabatically change the components of A to B (constraining any intermediate matrices to be Hermitian as well, but not necessarily positive definite) while \"following\" the eigenvalues ... will the mapping of the eigenvalues...
  19. N

    Deriving the Adiabatic Expression for a Van der Waals Gas

    For a van der Waals gas experiencing an adiabatic process derive the following expression: T(V-nb)^(R/Cv) = Constant I tried using PV^gamma = Constant with gamma = Cp/Cv and Cp - Cv = nR with PV = nRT but could not get it. Any hints? I would have to use Boyle's law to account for...
  20. C

    Adiabatic Process for an Ideal Gas

    During the compression stroke of a certain gasoline engine, the pressure increases from 1.00 atm to 20.3 atm. Assume that the process is adiabatic and the gas is ideal with (gamma)= 1.40. (a) By what factor does the volume change? Vfinal = (ans)*Vinitial (b) By what factor does...
  21. V

    Adiabatic process and heat exchange

    All the places I've searched I find that the change in the internal energy for the adiabtic process is dU = C_V\,dT But I don't understand why they use C_V, neither the volume nor the preassure is constant during the adiabtic process.. I know that dU = C_V\,dT = C_p\,dT - p\,dV...
  22. M

    How is adiabatic invariant proved in a simple dynamic system?

    I'm reading a book on quontum mechanics in japanese (Quontum Mechanics by Shinichiro Tomonaga) and am stuck in proving the action variable "J" is constant in a one dimensional cyclic movement. i.e. The action variable "J" created by the trajectory of H(p(t),q(t),a(t/T)) = E(t) doesn't...
  23. C

    Adiabatic electrical Thermodynamics question -

    Adiabatic electrical Thermodynamics question - Please Help! The question is a thermodynamics question where the system is a resistor in a circuit; the question is as follows: A thermally insulated (Adiabatic) resistor of 30 Ohm's has a current of 2 Amperes passed through it for 1 second. It...
  24. E

    Adiabatic Process: No Energy Change but Temperature Change?

    In an Adiabatic Process no heat energy is trasferred into or out of the system so there is no energy change, BUT, there is a change in pressure, volume and temperature. But when atoms or molecules gain/loose heat energy they vibrate more/less respectively. And the measure of the vibration of...
  25. C

    Thermodynamics problem; App of 1st law, work, adiabatic processes, and enthelpy

    The question is as follows: the partial derivative (given as a partial, but i don't know the notation, so letter d is really little delta for the partial) (du/dT)p = Cp - P(Beta)v where Beta = expansivity coefficient = 1/v (dv/dT)p again, all the "d's" are lowercase delta's for the...
  26. P

    Adiabatic Expansion Temp: 500K to 6.5x Monatomic, Diatomic (No Vib) & Vibrating

    An ideal gas at 500 K is expanded adiabatically to 6.5 times its original volume. Determine its resulting temperature if the gas is as follows. (a) monatomic (b) diatomic (no vibrations) (c) diatomic (molecules do vibrate) Anything to get me started?
  27. S

    How Does Temperature Change with Volume in a Quasi-Static Adiabatic Process?

    Hello Friends! can anybody help me? show that for a quasi static adiabatic process of an ideal gas, the following reaction holds TV^{\gamma-1}}=constant Secondly::: At about 100ms after detonation of a uranium fission bomb, the "ball of fire" cosists of a sphere of gas with a...
  28. A

    Does an Irreversible Adiabatic Process Defy the Equation PV^(gamma)=constant?

    Why doesn't an irreversible adiabatic process follow the equation, PV^(gamma)=constant?
  29. B

    Carnot Cycle and Adiabatic process

    I have a question regarding Carnot Cycles and Adiabatic processs. I have cylinder with n moles of a mono-atomic gas with a specific Volume, Pressure and Temperature. This Cylinder is closed by a piston. This system undergoes the four step Carnot Cycle A-B, B-C, C-D and D-A. A-B: Is...
  30. E

    Adiabatic expansion of argon gas

    argon enters a turbine at a rate of 800 kg/min, a temp of 800C and a pressure of 1.5MPa. It expands adiabatically as it pushes on the turbine blades and exits at a pressure 300KPa. Calculate its temperature at exit. The equations I am working with are PV^(gamma)=constant and...
  31. E

    Adiabatic Expansion: Solve for Final Volume of Gas

    Sorry about the repost, but I am frustrated with this problem. An ideal monatomic gas, consisting of 2.47 mol of volume 0.0890 m3, expands adiabatically. The initial and final temperatures are 22.3oC and -64.3oC. What is the final volume of the gas? I've tried solving for P in terms of T...
  32. E

    Adiabatic Expansion of 2.47 mol Ideal Gas: Final Volume Calculation

    An ideal monatomic gas, consisting of 2.47 mol of volume 0.0890 m^3, expands adiabatically. The initial and final temperatures are 22.3oC and -64.3oC. What is the final volume of the gas According to a formula in the book, the volume of an ideal monatomic gas' volume expands by 1.52, but I...
  33. V

    How Do I Calculate Temperature and Pressure Ratios in an Adiabatic Engine Cycle?

    This one had three bullets by it so it's a pretty tough one. Work and rambling thoughts so far... please tell me if I'm wrong. This would be a change in entropy problem for the first couple of ratios right? (delta)S=Sfinal-Sinitial=nRln(Vf/Vi)+nCvln(Tf/Ti) yet it is an adiabatic operation...
  34. B

    Adiabatic Theorem: Finding Coefficient for State Transitions

    How do you find the coefficient for a transition from one state to another using the adiabatic theorem? I've looked in a couple different books and their answers are different. Thanks
  35. S

    Calculating Work in an Adiabatic Process for a Diatomic Gas

    I have 5.00 mol of O2(Oxygen) at 20.0 Celsius and 1.00atm. I will compress this to 1/10 the original volume. Find the work? The correct answer is 46.1 Kj I am having a terrible time with this. This is what I know: Q = 0 for an adiabatic process, and the change in internal energy is...
  36. K

    Energy conservation in adiabatic process?

    Hi there, after years of blissful unawareness, I suddenly managed to find a simple yet, annoyingly perplexing question regarding our old friend, the adiabatic process. Let's look at the facts. Any textbook will tell us that in an adiabatic process no heat is exchanged between the system and...
  37. S

    Solving Adiabatic Process Problem: Find Final Volume & Pressure

    I have this problem and I do not have the answer, but I get an answer that I feel is probably wrong, so can someone please check my work and point out where I went wrong?? Here is the problem: moles = 0.10 of O_2 T(initial) = 150 C = 423 K P(initial) = 3.0 atm = 303.9 KPa The gas...
  38. A

    Work done in a reversible adiabatic change

    Can anyone help me with this? -- Show that the work done in a reversible adiabatic change from an initial state (p1, V1) to a final state (p2, V2) is: W = ( p2V2 - p1V1) / (gamma - 1) -- Here's what (little) I have done so far: Reversible => dW = -pdV Adiabatic => dq = 0...
  39. C

    Solve Adiabatic Process of Ideal Monatomic Gas (γ=5/3)

    A fixed quantity of an ideal monatomic gas (γ = 5/3) is being taken around a cycle p1 = 10 atm V1 = 2 L T1 = 370 K V2 = V3 = 15 L p2= 4/3 Here's what's happening: During the isothermal process, the gas expands while in contact with a large heat reservoir, so its temperature remains...
  40. nucleartear

    Adiabatic theory of perturbations

    Hello there! Do you know any good link about the adiabatic theory of perturbations? (theoretical mechanics) thanx!
  41. M

    Adiabatic Processes in the Carnot Cycle

    I'm not sure I understand why the Carnot cycle involves adiabatic processes at all. I can't seem to find a reason. Also on a related note, how exactly does a Carnot heat pump (refrigerator type) work? Is the sequence the same as a Carnot heat engine?
  42. S

    Adiabatic Expansion - Need help getting started

    Hi, I just need help getting started on a question.. I'm not even sure where to begin: It is desired to ignite a gas at 1000 degrees celcius by compressing it adiabatically to 27 degrees celcius. a) by what ratio must its volume be changed? I'm not really sure how to approach this...
  43. T

    Question on adiabatic expansion

    I've been struggling with this problem for an hour or so now, and can't seem to find the right answer. Perhaps someone here can help? I would be very grateful. ;) Two moles of an ideal gas ( = 1.40) expands slowly and adiabatically from a pressure of 5.09 atm and a volume of 12.7 L to a...
  44. M

    Adiabatic Theorem: Thermodynamics & Quantum Mechanics

    When studying Thermodynamics, we make much use of adiabatic processes where a change is made so fast that no significant heat can flow. For example, the compression stroke of a diesel engine. In quantum mechanics, it seems they turn the definition on its head, adiabatic is defined as a...
Back
Top