I am looking for a way to calculate the pressure drop not just the answer. Can you refer me to any tabulated pressure drops results for steam that you mention?
What you are really asking for is a two-phase pressure drop correlation. I suggest you look into the Lockhart-Martinelli correlations. A quick Google search turns up lots of references.
You are asking a simple question to a very complex problem. There are a many factors involved in the calculation of two-phase pressure drop. I would recommend that you start looking at your favorite technical bookstore for something that has this general title:
Boiling Heat Transfer And Two-Phase Flow
Wait until you see what you're getting yourself into! If you are serious about this branch of heat transfer / fluid flow, ASME has an on-line course dealing with this very subject. I found it very useful.
Wolverine Tube publishes an Engineering Data Book that has a chapter on two-phase flow. If you check this out, I believe you will see what you are getting yourself into. For condensing relatively low pressure steam, you could use Lockhart & Martinelli as Speco suggested. For higher pressure steam, use the Homogeneous Flow Model.
Please be careful with using the Wolverine material. It's not that there is anything wrong with it, it's just that I think you work with finned tube air-cooled exchangers and NOT tube and shell like the Wolverine info is meant for. Tube orientation and circuitry are critical to the methodology you use when calculating this type of heat transfer. Generally speaking, tube and shell designs for condensing service consist in a bundle of individual tubes that don't communicate except at their inlet and outlet. This is not like the product on your reference website so far as I can tell.
