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Equation for

Equation for

Equation for

(OP)
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.

RE: Equation for

(OP)
Dear MVD,

Thanks for your quick and useful reply.

RE: Equation for

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

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.

RE: Equation for

(OP)
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

RE: Equation for

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.

RE: Equation for

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.

RE: Equation for

Hello Patrick,

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

RE: Equation for

(OP)
Dear M/s.Pronab/Perth1/25362

Thanks a lot for the very useful info.

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