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 rendra April 5, 2000 02:33

steam properties

Hi, I am student of mechanical engineering at Bandung institute of technology (Indonesia).

I have some trouble during modelling steam flow along steam turbine blade to determine steam properties.

i assumed that flow is adiabatic, turbulent, compressible, with varied density and viscousity.

can anyone give me further information related with defining steam properties ?

how can i define equation model for steam density and viscousity variation?

can i set steam properties as ideal gas properties?

 Adrin Gharakhani April 5, 2000 13:54

Re: steam properties

Steam is one of the most commonly studied subjects, and information about it can be found in the most introductory thermodynamics books.

As for the ideal gas law assumption, it depends on the range of temperature/pressure operating conditions. For a certain range the ideal gas law can be used quite successfully. Again, you need to check your thermodynamics books and check the library for steam tables/equations. Similary, for viscosity variation you can find model equations in the same books.

PS. It doesn't matter whether you have turbulent or laminar flow!

 B O Bamkole April 6, 2000 02:25

Re: steam properties

The appendix of the paper gives expressions for properties of steam.

"The Spontaneous Condensation of Steam in Supersonic Nozzles" by J.B. Young, PhysicoChemicalHydrodynamics vol 3, No. 1, pp 57-82, 1982.

The equation of state is due to Keenan and Keyes in Steam Tables i.e

P = rho * R*T *( 1 + B *rho + C *rho*rho)

Depending on the accuracy you require you may be able to use the ideal gas law. Other people find that just one virial coefficient is enough.

His expression for viscosity is taken from the UK steam Tables.

 Alton Reich, PE April 10, 2000 11:47

Re: steam properties

My favorite set of steam tables is the one published by ASME. It has a section at the beginning listing the equations they used to generate the properties in the tables. I don't have my copy here in the office (it's at home in a box, somewhere), to give you the ISBN #, but you should be able to order a copy off the ASME web site at: www.asme.org

Regards, Alton

 rendra April 13, 2000 02:48

Ansys flotran

any body can help me to use subroutine for my equation model in ansys flotran??? Mr. Bamkole, what is the content of B and C in your equation model??

Rendra

 B O Bamkole April 13, 2000 04:05

Re: Ansys flotran

Hi,

It is not in fact by model. The expressions are quite complicated which is why I gave the reference. The Steam Tables by Keenan and Keyes should be easy to obtain. The expression for B as quoted by Young (you might want to cross-check in the Steam Tables) is

B =2.0624 - (2612.04/T_G) 10 ^[100800/T_G^2 + 34900] where T_G is the gas temperature

while

C= 3.74 * 10^5( T_R-0.8774) e^(-9.30T_R +2.0)

where T_R is the reduced temperature

T_R= T_G/647.286.

The units for B is cm^3/g while the units of C is B^(2).

I may have made a typo somewhere so If you want to use this expression with any certainty you really should get a hold of the original papers.

Jide Bamkole

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