Explaining Adiabatic Cooling: What Is It & Why Does It Happen?

  • Thread starter Thread starter cdub27
  • Start date Start date
  • Tags Tags
    Adiabatic Cooling
AI Thread Summary
Adiabatic cooling occurs when compressed air is released from a tire, resulting in a temperature drop due to the air doing work on the surrounding atmosphere. As the air expands, it pushes against atmospheric pressure, which leads to a decrease in pressure and temperature according to the ideal gas law (PV=nRT). The internal energy of the air decreases because no heat is added during this process, causing the temperature to drop. This explanation aligns with the first law of thermodynamics, highlighting the relationship between pressure, volume, and temperature changes. Understanding these principles clarifies why the air feels cold when released from the tire.
cdub27
Messages
2
Reaction score
0
I understand that adiabatic cooling is the reason as to why, a valve releasing compressed air from a tire, would become cold. But I'm having a hard time grasping why this actually happens. I've been searching online, and I can't seem to find the type of simplified answer I'm looking for.

Could anyone explain this in a simple way, so I can understand the basic concept?

Thank you in advance.
 
Physics news on Phys.org
cdub27 said:
I understand that adiabatic cooling is the reason as to why, a valve releasing compressed air from a tire, would become cold. But I'm having a hard time grasping why this actually happens. I've been searching online, and I can't seem to find the type of simplified answer I'm looking for.

Could anyone explain this in a simple way, so I can understand the basic concept?
Apply the first law of thermodynamics. Ask yourself whether the compressed air in the tire does work as the air is released from the tire and enters the atmosphere. Is any energy (eg. heat) being added to the tire? If the air does work, and no heat is being added to the tire, where does that energy come from? So what does that tell you about the internal energy of the air in/from the tire? And what does that tell you about the air's temperature?

AM
 
Thank you AM,

Well from what I gather, the air does do work on the atmosphere by pushing it away against the atmpspheric pressure to make room for the expanded air. Which is caused by PV=nRT, which I believe means that the volume and nR remain constant; while P and T change. This relation means that the change in pressure will cause a change in temperature. Therefore when the valve releases the air, the air pressure becomes equalized to the surrounding air which causes it to cool down. Is this way off, or am I going in the right direction?
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

I Irreversible adiabatic processes & entropy change (clarification needed)
Replies
22
Views
5K
What Happens When Water Vapor Cools at Constant Pressure?
Replies
1
Views
1K
Optimization of barrel length in pneumatic cannons
Replies
26
Views
6K
Cooling System-What is the main purpose of the Compressor
Replies
4
Views
5K
How do you Calculate Ampacity of a Conductor Geometry?
2
Replies
64
Views
5K
Thermodynamics: Joule / Brayton Cycle - Specific Work Done Question
Replies
8
Views
3K
Adiabatic gas cooling/heating: Explaining Conceptually
Replies
2
Views
2K
Explanation of Isothermal vs Adiabatic Cooling
Replies
2
Views
3K
Pot cooking food and being cooled, how does the pressure change?
Replies
8
Views
5K
Understanding the Carnot cycle
Replies
3
Views
1K

Hot Threads

Recent Insights

Back
Top