Industrial Refrigeration---Forced Air Cooling Units

I'm sorry, but your question is loaded with misconceptions and makes almost no sense at all.

sorry for confusion, i simply asked what length of a finned pipe is needed to cool a certain cold room??

For example, suppose 100 ft of running length of plane pipe/tube of 1/2 inch OD is required to cool a certain room or space from 22C to -20C , then how much of it is required to cool down the same if it is finned, say at 1/8inch distance??

This looks like a good place to start. Sorry I can't help you more, but out of my area of knowledge.

Thank you... for the useful link.

Perhaps someone here can tell about the co-relation between the heat flux between a bare pipe and and finned pipe of same dimensions, presuming all other conditions are constant. I don't know whether a formula for the comparative ratio between the two exists???

Without knowing how well the room is insulated and how long "shortest possible run-time" means, Guvnor, the scheme will not respond to any calculation.

Why not buy a package from a specialist cold room supplier?

As I already stated the room was previously in operation and all conditions were set for performing.Insulation was okay too but no way insulation will hamper the air flow or kill what is called the ''thrust'.

Buying a new package could be a solution if science fails to answer my question!! Friend, sometimes you have to work with your ''hands and feet'' in a poor country like mine!!:)

Thanks for the interesting problem. Maybe the shortest possible run-time could be achieved by exhausting the 22C air from the ceiling as you feed in -20C air through the floor of the room.

The -20C replacement air could be provided by passing night air through a conduit chilled by suitable means. So instead of waiting for the puny heat flux of fins to take the heat out of a hot room, you dump all of that stale hot air and replace it with fresh cold air. Night would be the best time because your feed is pre-chilled. Your heat transfer operation will be in the confined and controlled space in the cold air feed conduit, a little air at a time with a lot of surface area for heat rejection for that little bit. As the cold air flows in, the hot air will be displaced to the exhaust conduit.

sorry friend, that's beyond the issue. The problem is air gone static when the height of a room was lowered (to reduce cubic space) when before reducing the room height the same room operated perfectly.

So the problem is air gone static. You also say that before the ceiling was lowered, there was no problem. If you had posed this problem as one of air flow and said it was a sealed room cooled by a Blast Freezer that used to be OK before the ceiling was lowered, you might have attracted the attention of the experts on air flow here.

The finned tube question was about heat flux in the abstract, but outside the context of the real problem (air flow) it made no sense. You thought you knew the answer and just needed to find out a few details. Maybe the answer is not in adding a finned tube system but simply installing some fans to assist the recirculating air flow back to the Blast Freezer so the room works like it used to before the ceiling was lowered. That would be easy to try, at least.

If you have a look at a standard Cold Air Blast Freezer you will note that there is no provision for fresh air intake and the whole freezer chamber is totally enclosed.

The air is thrown into a finned evaporator from axial fans attached to it at the back and discharged air comes out from the opposite open side of the evaporator (ie from the front). Product to be blast frozen such as fish is placed right in front of the evaporator grid. The strong air thrust coming through the evaporator hits the fish and freezes it down to about minus 30 degrees in 10 hours or so, depending upon the thickness of the fish , its initial temperature and the way it is stacked. There is only one door located right in front of the evaporator grid which serves both as entrance or exit .

OK, so you dial back the Blast Freezer to a powerful room cooler, then diffuse the blast through a network of nozzles so you have like a carpet of cool air seeping in from the floor. A modification of a known device? Instead of a network of finned conduits disposed within the room, a pressure wave to assist exhaust of the hot air. Air flow will require an exhaust fan, too. Thanks for your lucid explanation of the Blast Freezer. As you can tell, I'm new to this.

No, you haven't got the point.

Here is a diagram you to show you what a 'blast freezer' is.

Mine has just one door for Loading and Unloading, rest is same.

I hope the sketch now makes my question clear.

Hi friends!

Here is another sketch to make the concept clear.

In the present case the freezer room has one door for loading and unloading and fans are installed behind the evaporator to create the air flow from down up (ie anti-clockwise).

Thanks for the additional information. My original presumption was a standard walk in freezer that is more designed to 'maintain.'

Even though I do not know enough about this topic to contribute, I am enjoying learning about 'blast' freezers and the physics of how to rapidly transition non-frozen to frozen.

This thread is becoming educational for me, I hope you eventually find the information you are looking for.