Water / Steam evaporation calculation

[FloidRose]

Hello!

I'm trying to build simulation of steam generation process

My problem is this:

I want to know how to calculate pressure in the following problem-

closed container, V=1 litres
121 C water, 1 g
121 C saturated steam 1.129 g
p = 1 bar

if container valve opens shortly and 0.3 g of steam is led out what is pressure in the container after that?

Could yuo help how to address this problem

I have figured out that part of the water evaporates to steam. And it seems that PV=NRT equation can not be used?

Any help is appreciated

-Floid

 

[anorlunda]

Yeah you need to make differential equations and solve it for pressure versus time.

1. write mass balance equations
2. write volume balance equations
3. write energy balance equations

The difficult part is that volumes and energies are a function of pressure. You'll need access to tables of water and steam properties, and to find the partial derivates of specifc volume and enthalpy, use those as piecewise linear approximations.

When I did it years ago, it took me about 1 week to get the equations to work.