Yogurt incubating room heating

Big Will

I have a customer that we started working with about two years ago. They have a small plant that produces all kinds of dairy products using goat milk. In the incubation room they need 115 degrees to culture the yogurt. The problem is they keep getting stratification related problems that is keeping the lower product to cool. On of the new on site engineer has worked at facilities with blast freezers. He wanted to use the same high volume high velocity air movement idea here. The problem is the expense would be huge. IN a blast freezer they use a drop ceiling as a duct to draw air of the top of one end of the room and fans at the other end that blow the air across the product. this causes a horizontal air current at about 1000 FPM. The catch is in a 7 foot high 20 foot wide room that equates to 140,000 CFM. That means about five 36 inch prop fans. So has anyone been involved in a incubation room that needed extremely even temperatures at a high temp.  

Jamie Hall

Gotta admit,

no.  In fact, I don't think I ever thought about the requirements for a room for culturing goat's milk yogurt...



However, as you note the idea is to avoid stratification.  But that does not mean that you need the huge air velocities that you need for blast freezing; in blast freezing you are looking for a lot of heat transfer capability, which means moving a whole lot of air.  Here I don't think you have the same sort of problem at all, and so you don't need to move that great a volume of air.



On the other hand, your ceiling really is too low to use big overhead fans effectively.  This is sort of napkin at the bar thinking, but could you come up with a system which had a set of ducts along the floor (for reasonably even distribution -- probablly have grilles at intervals, which could be adjusted), a duct fan sized for perhaps fifteen room air changes per hour sucking air from those ducts, and a corresponding set of ducts overhead, discharging the air from the fan?  As I say, this is bar napkin thinking, but with some fiddling on the outlet grilles, it seems to me that you should be able to get a pretty even downwards air flow at about 3 inches per minute in the room which would break up the stratification completely.

Big Will

fans

They have eight commercial ceiling fans  in the room and two 30" fans one in each corner. Right now there is a lot of air movement in the room. It is not uniform though. Your idea would create a more uniform air change in the room than the existing idea. I think the existing fans actually fight each other somewhat. I was also thinking of putting large round ducts along one wall and across the ceiling with inline fans in them. If they pulled air from one wall high and discharged on the opposite wall low it seem like it would work.  It wold be cheaper than the false ceiling and 140,000 CFM. 

Gordan

Is there a reason

why they couldn't circulate the product instead?

nicholas bonham-carter

destratification methods

what about a blower/duct system sucking air off the ceiling, and exhausting it to the floor? some good filters could be incorporated as well. all the ducy/blower could be mounted outside the room itself, so you don't lose much space.

the source of heat could be a radiant floor. or wall.

naturally some readily visible thermometers, with maybe a remote readout, would enable the monitoring of the various height of shelving.--nbc

LarryC

How is the product loaded into the room?

How is the product loaded into the room?

 

If it is loaded by individual trays, how about radiant shelving?  Circulate 120 F water in the shelves and let conduction / radiation maintain the temperature.

 

If the product is rolled into the room on baker shelves, perhaps a center "wall" that is either the supply or return plenum with the opposite plenums on the other wall 10 feet away.  This would split the room in half lengthwise and reduce the vertical stractification by shortening the distance the air has to travel.

 

Taking this idea one step further, make the center "wall" the return that hangs down from the ceiling, and put the hot air supply ducts down low on the two end walls.

Big Will

I thought about radiant floor

It would be really expensive though. The product goes in on pallets loaded about 48 inches high. There may be times were it is stacked higher but I have not seen this. I keep searching the net looking for a book or guide on how to build something like this. I hate not having a point of reference. 

LarryC

Radiant wall radiators?

Can the warm air flow THRU the product containers on the pallets?  If the product is stacked on solid separators, it will be a bear to get the inner product up to temperature.



How about a combination of radiant wall radiators from 6" to 60" and floor grilles pushing up hot air?  Place the returns in the ceiling.

Charlie from wmass

I vote for a radiant floor and

walls. if you have lots of radiant area you can use constant circulation to keep the temperature constant. High volume, large area, radiant with feed back from the room to maintain a delta T as low as you can get away with. Radiant shelves would not be a bad idea if you went higher. The cost of the radiant heat and its components will be dwarfed by the electric bill of all those fans.

Cavedon

Thermal Equalizer/Destratification fans

I work for a company that has created a solution to the exact problem you face. Many of the products have been used in similar temperature controlled warehouses that store sensitive pharmaceutical products. With the proper density installed we have seen temperature control within +-2 degrees F. Sound like this is exactly what you need. Go to google and type in destratification fans or thermal equalizer and look for the Air Pear or Airius.