7 replies to this topic

[panagiotis]

My knowlddge on falling film evaporators is very limited.
I would like to ask you a bit "strange" question:the outlet stream of a falling film evaporator is a vapor-liquid stream. The temperature of vapor is different than the liquid?

[breizh]

Hi,

Let you study these materials, and you will get your answer.

You may need to purchase a book like Perry's chemical engineers' handbook to support your work. A one-time investment.

Good luck.

Breizh 

[panagiotis]

Hi Breizh,

Thank you so much for your reply!
You are always so helpful! I will read your documents. And I hope to find the answer! When I find it, I will come back to you!
I will take into consideration your suggestion and I will buy Perry's book.

[panagiotis]

I cannot open the first attachment!

[breizh]

Hi,

Try again

Breizh

[panagiotis]

Thank you so much
Breizh!

[MarceloKT]

Yes, the vapor can be separated from the liquid in a separator, so, you would hav two streams. The liquid is your product and vapor could be send to a condenser, for instance. There is a temperature diference, that is usually due to dissolved salts/sugar. The name of that is BPE = boil point elevation

My knowlddge on falling film evaporators is very limited.
I would like to ask you a bit "strange" question:the outlet stream of a falling film evaporator is a vapor-liquid stream. The temperature of vapor is different than the liquid?

 

[seuenergy]

The process of changing a liquid into its gaseous state is called evaporation. It energy needed for the transformation is known as  the heat of evaporation. That is the reason why temperature goes down.  Actually, the temperature of gas and liquid at the two phase boundary is the same. But as the remain liquid mass is much bigger. So the boundary liquid will be heated by deeper liquid. 

So in one sentence. The whole system temperature will go down. But the gaseous temperature will be a little lower than liquid.