Thermo Question: Saturated Mixture Heat Flux Impact?

  • Thread starter JD88
  • Start date
  • Tags
    Thermo
In summary, the conversation discusses a conceptual idea of a vertically oriented cylinder filled with saturated liquid and a constant heat flux being applied to the surface of the liquid. It is mentioned that as the liquid boils and turns into vapor, the temperature and pressure within the cylinder remain the same until all of the liquid has boiled. The question is posed whether the temperature at the top of the cylinder will begin to rise due to the heat flux, creating a mixture of superheated vapor at the top and boiling liquid at the bottom. It is also noted that in a closed vessel, the temperature and pressure will continue to rise as the water boils.
  • #1
JD88
110
0
This is just a conceptual think I have been thinking about. Hopefully I am not just missing something obvious.

Imagine we have a large vertically oriented cylinder filled completely with a saturated liquid and the surface contacting the liquid is providing a constant heat flux to the fluid. Since the liquid is saturated any heat we add to it will immediately cause it to start boiling.

Now from my understanding, as the liquid within the cylinder is boiling the cylinder contains a saturated mixture and it all remains at the same temperature and pressure, until all of the liquid has become a vapor. The vapor rises to the top of the cylinder because its density is smaller than that of the liquid.

So my question is this. Since the surface of the cylinder contacting the fluid is providing a constant heat flux, won't the temperature of the vapor at the top of the cylinder begin to rise even though all of the liquid has not boiled? So now there would be superheated vapor at the top and boiling liquid at the bottom? Or would all of the fluid in the cylinder remain at the same temperature and pressure regardless of how the heat is being applied?

Hope that made sense.
 
Science news on Phys.org
  • #2
The heat flux is the latent heat of vaporization. The saturated liquid and saturated steam temperatures are the same.

Note also that if this is a closed vessel, the temperatures will rise as the water boils and the pressure rises.
 
  • #3


I can provide some insights on this conceptual question. First, it is important to understand the concept of saturation. A saturated mixture is one in which the liquid and vapor phases coexist in equilibrium at a given temperature and pressure. In your scenario, the heat flux provided at the surface of the cylinder will cause the liquid to reach its boiling point, and any additional heat input will cause the liquid to boil and form vapor. This vapor will then rise to the top of the cylinder due to its lower density.

Now, as the vapor rises to the top, it will continue to receive heat from the surface and its temperature will increase. However, this increase in temperature will not cause the liquid at the bottom to also increase in temperature. This is because the liquid and vapor are in equilibrium, and any increase in temperature of the vapor will cause more liquid to boil and maintain the equilibrium. Therefore, the temperature and pressure of the entire system will remain constant until all the liquid has boiled and turned into vapor.

In summary, the heat flux provided at the surface will cause the liquid to boil and form vapor, but the temperature and pressure of the entire system will remain constant until all the liquid has boiled. Therefore, there will not be a situation where there is superheated vapor at the top and boiling liquid at the bottom. I hope this explanation helps clarify your conceptual question.
 

1. What is a saturated mixture?

A saturated mixture is a two-phase system where both liquid and vapor phases coexist at a given temperature and pressure. This means that the mixture is in equilibrium and any additional heat added will only result in a change in the amount of liquid or vapor present, but not the overall temperature.

2. How does heat flux impact a saturated mixture?

Heat flux is the rate of heat transfer per unit area. In the case of a saturated mixture, heat flux can impact the amount of evaporation or condensation that occurs. If the heat flux is high enough, it can cause a phase change from liquid to vapor or vice versa, resulting in a change in the composition of the mixture.

3. What factors affect the heat flux of a saturated mixture?

The heat flux of a saturated mixture can be affected by several factors including the temperature and pressure of the system, the physical properties of the mixture (such as specific heat capacity and thermal conductivity), and the flow rate of the mixture.

4. How is heat flux measured in a saturated mixture?

Heat flux can be measured using a heat flux sensor, which is a device that can measure the amount of heat passing through a surface per unit area. In the case of a saturated mixture, the heat flux can be measured at the interface between the liquid and vapor phases.

5. What are the practical applications of studying the impact of heat flux on a saturated mixture?

Studying the impact of heat flux on a saturated mixture is important in many industrial processes, such as power generation, refrigeration, and chemical processing. It can also help in the design of more efficient heat exchangers and other heat transfer equipment. Additionally, understanding the behavior of saturated mixtures can aid in predicting and preventing potential hazards, such as explosions or equipment failure.

Similar threads

Replies
32
Views
1K
Replies
2
Views
867
  • Thermodynamics
Replies
5
Views
983
Replies
16
Views
1K
Replies
1
Views
616
Replies
1
Views
791
Replies
11
Views
7K
Replies
3
Views
1K
Replies
3
Views
2K
Replies
26
Views
3K
Back
Top