Industrial carton freezer

Hi all

My company is currently looking to replace an 8 ton an hour spiral chicken freezer with an 8 ton an hour carton box freezer.
After approaching the relevant companies who specialize in this design we have obtained the necessary quotes and are starting the tender process. One thing we have noticed is that all the quotes show different kWr refrigeration capacity.
I decided to look into this and do my own research into the actual kWr calculations and have also always come up with different answers when using different methods.

Is there anyone out there who can help with this, I would appreciate the insight from a specialist

I wouldn't call myself a specialist, special maybe, but specialist, no. I digress.

Your query is not a new one. Basically comes down to variables, many many variables. Temperature of product entering spiral, speed of spiral, ambient temps used in calculations, makeup of carton itself, airspeed in spiral and the list can go on. Even down to the software each company use to determine kW rating. Each manufacturer will have different design points.

I suppose if all the quotes are in the similar region of kW ratings, you can't be far off the mark.

You could also, and this this is a dirty word to many, employ a fully unbiased, independent consultant. Put all the risk and responsibility (if consultants ever do this) on to them for the load design. Then that makes it easier for you as all your potential suppliers will be required to price to the same kW rating. etc.

As I may have said before on another post, Refrigeration is based on both the dark arts, experience, and sometimes good engineering!! :)

Thanks Goober

Your "special" insights were duly noted and greatly appreciated. Having read your post I think I might have not painted the best picture of the situation.

The company is looking to replace an existing spiral with a carton freezer. A carton freezer stacks cartons on what are termed racks and feed them through an inline tunnel. The reason I decided to look into this whole kW ratings is because existing abattoirs have complained about certain manufacturers not providing a machine that is capable of freezing there product to the core. The product being chicken, so you can understand the need for a fully frozen product.

With all these uncertainties with existing suppliers it seems I would be better off designing and manufacturing the machine myself.

get kompulsa on it :D

Look at heat load of this spiral. Heat of chichen, carton, el. motors, defrost heat, ambient heat should be removed. Heat of el. motors and defrost can be different.
This is large freezer and would not suggest you to design yourself. Ask right questions and find good supplier. First you should ask suppliers how they came to this kWr load.