Cold wall vs. Forced-Air, which is better?

[pezagent]

Hi guys,

I was wondering what the difference between cold-wall freezers and forced-air freezers are, besides the obvious, i.e., benefits of one over the other, etc... any thoughts would be appreciated.

Thanks in advance for your help.

[herefishy]

Depends upon the application. For what equipment do you have this option?

[Andy]

Hi pezagent,
what are these cabinet designs, I have never heard these expressions before
Can someone elaborate.
Regards. Andy

[herefishy]

Hi Andy,

I think pezagent's was question was more in general. And I'm going to take a shot at it. pez' is apparently comparing an ice cream dipping cabinet to an upright freezer cabinet.

In the case of a dipping cabinet or even a horizontal chest freezer, say.... you may note that the key term or observation in either case is the horizontal configuration of the appliance (loads or is accessed from the top.. "top-load") In these applications, it is not necessary to move the cold/hot air, because the cold air is heavier, and will be contained in the open top box.

This is due to the stratification of the colder (heavier) air and the warmer (lighter) air. as the air cools in the open top box, the warmer air is acutally pushed out, or cooled itself.

In the case of an upright freezer, whenever the door is opened, all of the cold air "spills" out of the box, and a quick recovery is desirable. To increase rate of heat exchange, and eliminate an drastically reduce stratification (after the door is closed), a fan is employed to force the air over the heat exchanging surface of the freezer (evaporator).

Air is actually not too bad of an thermal insulator also. In some instances (say a blast freezer) high air velocities are desirable in order to "blow-away" the warm insulating air that will surround a product to be cooled.

In some instances, say your dipping cabinet, employing forced air may cause the cold air to simply be blown out of the space intended to be refrigerated. Another consideration would be perhaps the irregular configuration of the stored products (like your round ice cream buckets) requiring considerable effort to distibute airflow evenly.

When appropriate, "cold-wall" heat exchange is less expensive to manufacture and requires little maintenance.

[Dan]

Herefishy, that's a wonderful treatise. Good overview. If I can expand on your thinking, there is much merit to not moving air.

I am amazed how well a cheap little roll-around spot merchandiser performs. Even without a lid on it!