Evaporator heat transfer

[eaboujaoudeh]

Hey guys, i'm confused about one thing and hope i can find some1 who can help me:
Ice maker machines contain the evaporator around the ice making drum of the machine. There are 2 methods we are thinking about:
1. Rapping the normal copper tubes around the drum, true we would face a high pressure drop, but we can just make multiple circuits.
2. the other method is to make a hollow cylinder around the drum, and release the refrigerant in the chamber without tubing, and then collect them on the other side!
What do u think of those 2 approaches guys? I'm especially wary about method 2 but my friends want to try it...plz some help..thnx
Elie Abou Jaoudeh

Elie Abou Jaoudeh

 

[gr2vessels]

Wraping a refrigerant coil around the container is not new, just less efficient than the "2-nd" version and it takes some heat transfer calcs plus the ability to control the refrigerant (if system leaks). I would suggest a vacuum (mild only) evaporator jacket around the ice cream container or better still, the white goods store in nearby should be able to sell you a new ice cream maker, most likely with 12 months guarantee.
Cheers,
gr2vessels

 

[eaboujaoudeh]

i don't think any1 would appreciate the project if i get an ice cream maker ..btw..how on earth are we supposed to calculate the thickness of this jacket around the conainer..and its not an ice cream maker, its an ice maker..
thnx

Elie Abou Jaoudeh

 

[25362]

I'm not an expert on ice-making machines, but from reading I gathered that wrapped coils on a drum (water inside) are used to produce ice chips 7-8 mm thick.

Refrigerated (fixed) drums covered with a sliding metal band and doctor blades, passing through (external) water, with about 70% submerged band surface, are used to produce ice flakes 2-3 mm thick. A smaller roller reduces the radius of the metal band and the formed ice layer loosens from the band and breaks off.

When the band is at -12 Celsius and the water at +10 Celsius, the rotational speed is about 0.75 rpm for 3 mm thick ice flakes.

 

[gr2vessels]

Sorry Ellie,
I still believe that the process you are looking for is similar to an ice crem making process, unless you are looking for an industrial ice maker. The calculations you are referring to are common pressure vessel calculations, in accordance with ASME VIII. I don't suppose that you are familiar with those calculations, hence the ice crem maker from the friendly corner shop is probably your best option (please understand that working with refrigerant is a highly specialised work and only specialised equipment should be used, to prevent severe burns or even explosion).
Having said that, I am familiar with the pressure vessel design and familiar with the design of the jacketed vessels, it is not that complicated as you might think. However, for practicality, you would need to talk to a PV designer for your calculations, before you attempt to weld any jacket around the ice drum.
Cheers,
gr2vessels