Equation for 1

[patrickraj]

Dear friends,
I use the following equation to calculate water VP.
Error is very insignificant as shown below:

VP.Calctd VP from
Temp°F Psia Steam Table %Error
212 14.701 14.696 0.040
259.28 35.650 35.0 0.145
292.71 60.071 60.0 0.1198
316.25 85.135 85.0 0.1589
341.25 120.154 120.0 0.1285
Someone could give similar equation for Specific Heat, Thermal conductiviy, Viscosity of water to feed in the EXCEL spreadsheet.

 

[CARF]

Hi,

http://home.hccnet.nl/m.dijk/pressure_drop_calculator/calcs/calcs.html

download to PDFs on bottom of web page,
MVD

 

[patrickraj]

Dear MVD,

Thanks for your quick and useful reply.

 

[25362]

From Chemical Engineering Nov. '91, in the temperature range of 273.15 K (32^oF) to 500 K (440.3^oF)

Liquid enthalpy (btu/lb)

H = -31.1247 + 0.96903T + 1.1301*10^-4T²

Liquid specific heat [Btu/(lb*^oF)]

Cp = 1.0152 - 3.6171*10^-4T + 2.1709*10^-6T² - 2.9831*10^-9T³

liquid viscosity [lb/(h.ft)]

visc = -0.23535 + 208.65/T - 2.074.8/T²

Liquid thermal conductivity [Btu/(lb*^oF*ft)]

k = 0.31171 + 6.2278*10^-4T - 1.1159*10^-6T²

The same article gives vapour properties. Maximum error (%) and standard deviations (%) are also tabulated.

 

[patrickraj]

Respected 25362,

Thanks from heart for your VERY USEFUL and quick reply.
Today, I also managed to get the same article from our library.
For liq viscocity, the error is about 20.23%, this is the highest also.
Any better equation is available for liq viscocity.

Thanks in advance

 

[25362]

I suggest you construct the polynomials yourself from tabulated values by using more degrees (constants) than given by the ChE article. This should bring down errors to acceptable levels.

 

[pronab]

Saturated temperature of water can obtain from the follwing thumb rule:

T = 100 (P)^1/4
Where , T = deg.C
P = Barg.

** Error is very negligible.

Best of luck.

Pronab.

 

[Mech85]

Hello Patrick,

A "Water Propeties Program" file is available for download for FREE from

http://www.cheresources.com/software.shtml

The link is a direct link to the executable file.

I have found the program very useful - it gives density, viscosity, Prandtl's number, Spec. Heat, thermal Conductivity, thermal expansion, Vapour pressure, etc for water between 0 and 150 Deg C.

 

[patrickraj]

Dear M/s.Pronab/Perth1/25362

Thanks a lot for the very useful info.