Need ideas on a Sushi Conveyor refrig system

[kengineering]

Hello all, It's been a while but I need your help once again with a very interesting project. I am refrigerating a self serve Sushi conveyor. http://www.internetscamsrevealed.info/userimages/SushiConveyorChain.JPG I have searched for a picture of one that is refrigerated but I cannot find one. I have seen one in use at the Whole Foods Market on Houston st. in NYC but it is not refrigerated either! Amazing that raw fish is placed out unrefrigerated. But nontheless Thats the challenge. There will be no R&D (rob and duplicate that is) here. But if you know of a company that is refrigerating one of these things please do tell.
We have chosen a design that the customer likes. It has an air tower between the two conveyor lines. A T-shaped plenum supplies refrig air to the perforated back with a curtain at the each edge of the T shooting refrig air down to a return just outside the rotating plates.
I think the most difficult task will be getting the air flow just right.
So my first question is; how do go about getting the proper amount of air? It has always been kind of trial and error. The build team has gone ahead and built a fan housing for 105 cfm axial (muffin ) fans. One for each foot of coil and although it may be a perfect guess it is just that, a guess. Is there a formula to determine the cfm required. How important are the watt ratings of the fan? I have seen both condenser and evap fan motors that are 6-watt or 9-watt leading me to believe that the power of the fan has an impact on performance. Also, does anyone know of any written refrerance material on this subject?
This will be a remote installation but wwe will testing it later this week I'll try and post some pictures. Ken

[Gary]

It seems to me that you first need to determine the design temperature and humidity requirements. You want to cool the sushi but not dry it out.

[kengineering]

Temperature is a tricky issue from what I've read. people do not want cold sushi rice but the fish inside needs to be cold. The issue as I understand it is the health inspector. Temps to pass inpection cannot exceed 41*f. with an optimum temperature between 34-38f. Seems the product is covered with a glass lid so RH is not as big of a concern. Ken

[Gary]

Being a conveyor I assume you will want continuous operation at a steady temperature?

For this you could use an EPR valve and adjust it until the product maintains the desired temp.

[kengineering]

Gary, the epr valve is a good idea. Heres the refrig system so far for each 10 foot section of conveyor. One R404a copland med temp air cooled 1-1/4 hp cond unit, to a sporlan EBFSE-A-C TEV, feeding two 6"x9"x 54" coils (24-1/2" tubes) in series. the thermal bulb is of course on the outlet of the second coil. The cond unit will be aproximatly 30 ft away so it is intended to use a 5//8 suction line.
The control circut will be carel t-stats controling solenoids for pump down between cycles. Ken

[Gary]

Why would there be cycles?

I may be picturing this incorrectly. I'm thinking this is a continuously running conveyor with one end of the loop in the preparation area and the other end in the serving area?

The product is placed on the conveyor in the prep area and then travels the loop endlessly until a customer takes it off the conveyor. Does that sound about right?

[kengineering]

You have it right. Yes the conveyor is a constantly running endless loop and you may be correct in that the refrigeration may run without an off cycle, except defrost to insure a clear coil. I'll begin testing tommorrow so I'll keep ya posted . Ken

[Magoo]

Hi Kengineering, an interesting project. Keep us all informed how things pan out.
As a lover of sushi, and having been to many sushi places in Tokyo. I did note at one that the chefs were taking ingredients from different temp fridges, and that air was blown up under conveyor loop keeping plates chilled. Some how they figured the if a choice went around x times it was taken off conveyor. And also airconditioning was cooler than usual around pick and eat conveyor. Did not do much for warm saki.
magoo.

[kengineering]

Fathers day request.. Dad needs a new camera. Sorry no pictures guys. So her's how she turned out. Picture two very short ( 12 inches ) self select air screen mechandisers back to back. I didn't need very much supply air from the back as at first it blew the air screen out from the unit. after closing some of the rear holes with tape the front curtain kept refrigerated air in much better. After confirming this with a smoke test the case was cycling at coil temps of 18 to 34*f.
Fortunately this project turned out really well and all things I was worried about did'nt become an issue. This both good and bad because it left me with more questions than answers. Such as the relationship between the airflow and the refrigeration system.
Thanks to all for your comments, till the next fire drill. Ken