View Full Version : A curly load calculation

12-08-2015, 03:00 AM

I have a large storage room, 30m x 11m x 5.5m. 14 degree C room temp. Final weight of product when room fully loaded 600,000kg.

However, here's the tricky bit. The product takes 7 days to be loaded into room and must have a slow pull down of 2 weeks and the room must be running when loading.

So, first day 85,714kgs gets loaded, 2 week pulldown clock starts, second day next 85,714kgs gets loaded, 2 week pulldown clock starts, and so on till 7th day (when God rested, and my brain exploded) when room gets shut up for long term storage.

How, do tell, does one calculate the load for this project?

Strictly speaking, if we adhere to the supposed critical 2 week pull down requirement, it can't be done in one room...

Regards Goober

12-08-2015, 06:09 AM
Hi Goober.

No wonder your head has gone!

With the info you have supplied It does indeed not make sense!

The heat loads being introduced are erratic and unstable, sounds like a lot of blast freezers I have visited.
Good Luck Grizzly

12-08-2015, 06:12 AM
Hi Goober.
develop a heat load profile, work from there. Add base structural load as a given.
PM if you want to.
Sounds like a cheese curing /maturing system.

12-08-2015, 07:38 AM
:) sounds like a fun project. These conundrums makes the job more interesting than the usual.
As Magoo says profile the load, you are only varying your mass and pull down time over the seven days. Then it is stable for pull down and hold temp.

The controlling of plant is way more involved than the load calc as you need to vary your heat exchange surface theoretical size while I am guessing maintaining close RH control.

You will also need to consider ambient infiltration during loading and product entering temp variances to give a stable control strategy over the seasonal changes.

12-08-2015, 07:57 AM
You are right. Till there is a loading in the room & unless the each day's loading is in a way separated out, the temperatures shall be fluctuating & getting two weeks pull down period seems unrealistic.

So after the last day of loading the pull down period can be considered.
Plus what our experience shows that the earlier cooled material gives out its temperature when fresh material is loaded & undergoes temperature shocks till the entire loading is complete.
This is typically a scene in cooked products line & they are chilled before freezing & the loading keeps taking place through out the day till the production is on.