Leidenfrost effect at thermodynamic equilibrium

In summary, the conversation discusses the thermodynamic equilibrium of a spherical drop floating on top of the vapor of the same substance. The drop has a surface tension σ and the task is to show that PL≠PV at equilibrium and calculate the difference. The solution involves applying the three laws of thermodynamics and maximizing entropy, resulting in PL-PV=3σ/a, where a is the radius of the drop. The dimension of the result appears to be correct, but further verification is needed.
  • #1
digogalvao
14
0

Homework Statement


A spherical drop of a pure substance floats on top of the vapor of the same substance so the system vapor+drop is isolated. The drop has a surface tension σ. Show that at the thermodynamic equilibrium PL≠PV and calculate the difference.

Homework Equations


Three laws of thermodynamics

The Attempt at a Solution


I solved this one already but I would like to check my result. Following the three laws of thermodynamics and maximizing the entropy at the equilibrium yadda yadda yadda I got PL-PV=3σ/a, where a is the radius of the drop. The dimension of the result seems correct.
 
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  • #2
Is there a question here? If the question is "Am I right?", you have to supply the "yadda, yadda, yadda" so that someone can check your work and point out possible mistakes.
 
  • #3
kuruman said:
Is there a question here? If the question is "Am I right?", you have to supply the "yadda, yadda, yadda" so that someone can check your work and point out possible mistakes.

Ok...
For σ=0, Thermodynamic equilibrium says: PL=PV, but if we add a work therm for the liquid -σdS=-3σdV/a we get PL-PV=3σ/a.
 

Related to Leidenfrost effect at thermodynamic equilibrium

1. What is the Leidenfrost effect at thermodynamic equilibrium?

The Leidenfrost effect at thermodynamic equilibrium occurs when a liquid comes into contact with a surface that is significantly hotter than its boiling point, causing a thin layer of vapor to form between the liquid and the surface. This vapor layer insulates the liquid, allowing it to float and move around on the surface without boiling away.

2. How is the Leidenfrost effect at thermodynamic equilibrium different from the regular Leidenfrost effect?

The regular Leidenfrost effect occurs when a liquid is dropped onto a hot surface, causing it to form a vapor layer and skitter around. However, this effect only lasts for a short time until the liquid eventually evaporates. The Leidenfrost effect at thermodynamic equilibrium, on the other hand, is a stable state that can last for an extended period of time as long as the temperature of the surface remains constant.

3. What are the factors that influence the Leidenfrost effect at thermodynamic equilibrium?

The Leidenfrost effect at thermodynamic equilibrium is influenced by several factors, including the properties of the liquid, the surface temperature, the surface material, and the environmental conditions such as air pressure and humidity. Additionally, the shape and size of the liquid droplet can also affect the formation and stability of the vapor layer.

4. What are the potential applications of the Leidenfrost effect at thermodynamic equilibrium?

The Leidenfrost effect at thermodynamic equilibrium has potential applications in various fields, including heat transfer, energy conversion, and material processing. For example, it can be used to improve the efficiency of boiling processes, reduce friction in engines, and create self-cleaning surfaces. It can also be utilized in the production of microscale devices and in the study of phase transitions.

5. What are the challenges in studying and understanding the Leidenfrost effect at thermodynamic equilibrium?

One of the main challenges in studying the Leidenfrost effect at thermodynamic equilibrium is the complex interplay between various factors and variables that can affect its formation and stability. Additionally, it can be difficult to accurately measure and control the temperature of the surface and the properties of the liquid, making it challenging to replicate and compare results. Further research and advancements in experimental techniques are needed to fully understand and utilize this phenomenon.

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