Blast Chiller design

[Royal241]

I have a customer in the sushi catering business. The health inspector requires him to bring the rice temperature from 100F to 40F within 90 minutes. There is an existing medium temp walk-in cooler that just takes too long. The cooler is 7'x7'x7 with door heaters. The load is 100 lb rice at 100F. My thinking is to install a low temp condenser and evaporator across from the existing unit. Install a two way switch outside the door and alternate the freezer for 3 hr and the rest 21 hr for the holding medium temp. I would have the freezer thermostat probe inserted in the hot rice. There are no vegetables for storage, just fish (that's already frozen, waiting to thaw for next day use). Did you guys ever come across anything like this? Is there something that I'm not aware of, is this going to work? Ohh, when the thermostat reaches 36F will stop the freezer, i will have an alarm or a light go on and the dude will know to switch to holding medium temp unit. Any ideas would be appreciated. Thank you guys!

[Royal241]

23 views and no clue? Come on guys!

[mad fridgie]

Air flow (stack velocity)

[Royal241]

Waiting for Gary's take on this. I'm sure he did some crazy things in his life! Well, I'm going for it, in about two weeks.

[mad fridgie]

It is not just about temperature, you need to focus on how the heat is removed from the rice, how is the rice placed in the room, in a big deep bucket? or a shallow tray with lots of surface area (which is better).
just installing an extra fan blowing around the product could also achieve your desired results.

[Royal241]

2inch deep trays on shelfs. This guy is really scared of the health department and I want to help him.

[mad fridgie]

2inch deep trays on shelfs. This guy is really scared of the health department and I want to help him.

Place fans angling just over the trays

[Royal241]

Sounds like a good idea, but will dry the product. They usually wrap the trays but never that good.

[Gary]

Yep... the trick is transferring the heat from the rice to the air and that requires lots of air flowing over, under and around the trays.

[Gary]

Sounds like a good idea, but will dry the product. They usually wrap the trays but never that good.

The colder the air, the drier the product.

[Royal241]

The colder the air the dryer the product, makes sense, so what am I supposed to do? I was thinking colder air = shorter period of time

[Royal241]

How about this? I put another 1hp with the blower 2feet under the existing blower and tell the guy to put his rice on the opposite wall. When not needed shut one down.

[Royal241]

They will short cycle and there we go again

[Gary]

The colder the air the dryer the product, makes sense, so what am I supposed to do? I was thinking colder air = shorter period of time

Or... more air = shorter period of time

[Royal241]

Ok Garry, i will test that. It makes sense, I will let you guys know what happened before the weekend.

[Royal241]

I didn't touch that thing yet. We had a lot of snow here in Boston. I have a nice plan and will post pictures. Maybe 3 more weeks, still waiting for the electrician to bring me some "juice". I have to install a central ac and other coolers, so will take a while, but i will be posting the results!

[ernestlin]

For rice, I wonder the DX chilling is better choice. If use cold air for chilling, the moisture will be lost, it will make a big negative effect on rice quality. So a cold room is not the best choice.

[binti]

What about sitting the 2inch trays in another tray filled with water? Even salty water or brine solution. Better for heat transfer than air.

Just a thought