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hi,i am a student.In my final project,i had to design a small system of refrigeration system.Now i have a problem to calculate the length of evapurator.Have anyone can help me this this problem??
I really have no idea to find out how long the evapurator i need.
Or someone who can introduce me the book regarding to my problem.
hello heanboon,
I have a suggestion. Approach a local refrigeration spares company and ask them to select both a condensing unit and evaporator for you based on the size of the refrigeration space you are using together with the desired temperature.
They will arrive at a duty , either in BTU's or Kwatts, watts, whatever.
The "size" of the evaporator is measured in watts and is matched against the duty of the compressor.
In a nutshell, you achieve a balance of the two. As an aside, you need a lot of experience and brains to work it out scientifically. And you need to embark on a PHd if you want to work it outself. Dont even try.
And if youre designing a system, then you would, or should know all this stuff already!!
Dunno, maybe other members can be more constructive then I have been
Good luck
Work with us on this one..
Are you looking at air cooling or fluid cooling?
Is this a domestic size application e.g. you don't want a fan to increase the heat transfer rate.
Are you working at high (ambient) temperatures or are you in the frozen zone.
I guess you are looking at a small air cooled unit in which case you have several local suppliers making Searle, Kuba and Friga Bohn copies. For a really small unit you will be looking at a flat plate normally sold as a repair item or in 1000's off.
Evaporator capacity is rated as Q=AxUxTD
Heat transfer in watts = surface area (including fins) x conductance figure x log mean temperature difference external temp to refrigerant temp.
Work with this and you will end up with an evaporator far larger than you need. I know I tried and Aiyub is 101% correct designing from scratch ain't practical.
Try R J Dossart -Principles of Refrigeration
and for the PhD D's amongst you;
Webb - Principles of Enhanced Heat Transfer
www.searle.com will give you spec selection data on evaporators and fin coil selection data.
I'd also recommend SWEP for liquid / liquid heat exchangers on www.swep.se
'cause they just helped me out the mucky stuff with some failed Scandinavian stuff.
Go on give us the duty and more info and we will have a go.