## Enthalpy value calculation

## Enthalpy value calculation

(OP)

how can i calculate enthalpy value tank inside. If i know vapor pressure of liquid tank inside. e.d:

tank volume : 18m3

Vapor pressure at 20ºC =9 bar

Pressure tank= vapor pressure

tank volume : 18m3

Vapor pressure at 20ºC =9 bar

Pressure tank= vapor pressure

## RE: Enthalpy value calculation

R22's saturation v.p. at 20

^{o}C is 9.1 bar abs. This is no estimate, data were taken from published tables.## RE: Enthalpy value calculation

and the NPSHa = 0

This mean That :

absolute pressure = vapor pressure.

What is the pressure at the pump inlet ?

Pressure inlet= absolute pressure-Vapor pressure+ static head- pipe losses .

If NPsha =0

Pressure inlet= vapor pressure???

Could you help me ?

## RE: Enthalpy value calculation

Since the NPSH expressed in m or ft of liquid, measured at the pump suction, is

^{2}/2ga value of zero would mean that

^{2}xsp.gr.)/2gWhen the second term is small in comparison with Pv, as it generally is, one may say that when NPSH=0, P=Pv.

where

P is the absolute suction pressure

Pv is the vapor pressure of the liquid at the pumped temperature

u is the velocity of the liquid at the section where measurements were taken

g is the acceleration of gravity.

Hasta pronto y buena suerte.

## RE: Enthalpy value calculation

Raoult- Dalton laws?

## RE: Enthalpy value calculation

## RE: Enthalpy value calculation

But I don´t know what dose mean some of this.

Isothermic conditions:

The value of volume of differents phase , is lts of vapor or liquid per each mol of Propane at this pressure and temperature.

THis a good adress¡¡

sorry

Thank you

## RE: Enthalpy value calculation

Please work with a local chemical or pump engineer to calculate what you need. You seem confused on the concepts of enthalpy, NPSH, and composition. At this rate I'm worried you will improperly apply these formulas and unknowingly proceed with the wrong value in purchasing equipment. Good luck.

## RE: Enthalpy value calculation

^{3}, g/mL, kg/m^{3}, lb-mole/ft^{3}, lbm/ft^{3}, and so is also with specific volumes (the reverse units). The table also says at the end of each row whether the properties belong to a liquid or a vapour. While switching from saturated liquid to saturated vapour on two consecutive lines at different pressures you get the properties of both liquid and vapor. By combining the proportional individual enthalpies you get the enthalpy of the mix.## RE: Enthalpy value calculation

wt% flashed = 100 x (H

_{l,p1}-H_{l,p2})/H_{v,p2}where

H

_{l,p1}is the enthalpy of the liquid at pressure P1H

_{l,p2}is the enthalpy of the liquid at pressure p2H

_{v,p2}is the latent heat of vaporization at p2.