# Time constant for Liquid to Gas flashing off.

• 246ohms
In summary, the conversation is about the time it takes for a volatile liquid to evaporate when the pressure is reduced and whether there is a law or equation that can give the time constant for this process. The person is working on a pressure reducing device and is interested in finding out more information about this topic.
246ohms
I am having a problem finding out how long it takes for a volatile liquid to evaporate when suddenly the pressure is reduced.

For example - let's assume liquid butane at 8 bara is suddenly dropped to 1bara, the process of liquid turning to gas is not instantaneous so how long does it take.

Is there any law or equation that gives this time constant.

I am working on a pressure reducing device and any delay in the flash off from liquid to gas makes a big difference in the equations used to calculate the devices thermodynamic properties.

Thanks 246ohms

That's a great question, 246ohms. Unfortunately, I'm not sure if there is an exact equation or law that can give you the time constant for the process of liquid turning to gas when the pressure is suddenly reduced. However, I would suggest looking into the Clausius-Clapeyron equation as it may be able to give you some insight. Good luck with your project!

for bringing up this important issue

I can provide a response to your question about the time constant for liquid to gas flashing off.

The time it takes for a volatile liquid to evaporate when the pressure is reduced is determined by several factors, including the properties of the liquid (such as its boiling point and vapor pressure), the temperature, and the pressure change. There is no single law or equation that can accurately predict this time constant for all liquids.

However, a commonly used equation in thermodynamics, known as the Clausius-Clapeyron equation, can provide an estimate for the time it takes for a liquid to evaporate. This equation relates the vapor pressure of a substance to its temperature and can be used to calculate the rate of evaporation. Keep in mind that this is an approximation and may not account for all factors that affect the evaporation process.

In addition, the time constant for liquid to gas flashing off can also be affected by the design and efficiency of the pressure reducing device. It is important to consider these factors when calculating the thermodynamic properties of the device.

I would recommend conducting experiments or simulations to determine the specific time constant for your particular liquid and pressure reducing device. By varying the pressure and temperature conditions and measuring the rate of evaporation, you can obtain more accurate data to use in your calculations.

I hope this information helps in your research and development process. Best of luck with your project.

## 1. What is the time constant for liquid to gas flashing off?

The time constant for liquid to gas flashing off, also known as the flashing time, is the time it takes for a liquid to completely transition into a gas phase.

## 2. How is the time constant for liquid to gas flashing off calculated?

The time constant for liquid to gas flashing off can be calculated using the following formula: τ = V / A, where τ is the flashing time, V is the volume of the liquid, and A is the surface area of the liquid.

## 3. What factors affect the time constant for liquid to gas flashing off?

The time constant for liquid to gas flashing off can be affected by several factors, including temperature, pressure, and the properties of the liquid, such as its viscosity and surface tension.

## 4. How does the time constant for liquid to gas flashing off relate to the rate of evaporation?

The time constant for liquid to gas flashing off is directly related to the rate of evaporation. A shorter flashing time indicates a faster rate of evaporation, while a longer flashing time indicates a slower rate of evaporation.

## 5. Can the time constant for liquid to gas flashing off be manipulated?

Yes, the time constant for liquid to gas flashing off can be manipulated by adjusting the factors that affect it. For example, increasing the temperature or reducing the pressure can decrease the flashing time, resulting in a faster rate of evaporation.

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