Heat Transfer calc on Falling Film Evap type on Tube Icemaker

[llewelyn]

im planning to design an NH3 tube ice maker system,now,my primary problem is the Evaporator design,im thinkin bout the so-called falling film type wherein water is circulated again and again on the vertical tubes,but im stuck on the film coefficient calculations knowing that it continually changes as ice films are formed on the tube walls....anyone can help me figure out any method for this case????or any relation/empirical formula???it really takes me confused considering the fact that it involves a two-phse heat and Mass flow,right???please i need ur help and expert knowledge guys.....

also,if ever,im looking for the second option of using brine and tube-shaped cans instead of the falling film system.....is it any good as a replacement?????

hoping for your help.....

[iv attached an image for a clearer description:]

it shows thhat for some period of time,a film of water passes thru the inner surface of the tube, this thin film solidifies and ice is formed,then when water is
recirculated again,another layer of icefilm is added on the first layer until a Volume of ice finally fills up the whole tubespace...this is then the
harvesting is done thru hot gas defrost.

i really cant devise relations and empirical equations till now...all i know that this involves some damn complicated two-phase transient heat transfer....:confused: :confused:

[icemeister]

Are you trying to re-invent the wheel? There are a number of vertical tube icemaker manufacturers out there already using essentially the same design you show. The ASHRAE 2006 Handbook has a piece on a similar design.

Here's something that might help with the heat transfer. It costs $30, but it looks like it's just what you're looking for:

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V2P-4J0NXXD-2&_user=10&_coverDate=09%2F30%2F2006&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=859d1f38a39e17f89a72f195901b841d

[llewelyn]

sir,i just badly need it at school for our refrigeration eng'g subject and iv read a shelf of books but still cant find any resources,also i did a lot of googling but still no luck.....

iv come across with sciencedirect..yes,really good reference but unfortunately i dont have the capability with online purchase...my bad....