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smpsmp45
11-07-2015, 07:41 AM
Hi!!

One of our clients is interested in knowing the Relative Humidity in cold store working at -20 Deg C.

Are there any technical articles on this subject and/ or practical experience of our experienced members?

hookster
11-07-2015, 11:12 AM
Hi
Best option would be to get some readings in your store or back engineer the design.
Sublimation of product at freezing temperatures is well recorded and can be researched on your clients specific product and psychometric conditions calculated.

RH is depending on design conditions, product and equipment operation.Your dry bulb temperature and evaporation temperature (SST).

The wider the store TD has been designed the lower the RH and the closer the TD to holding temperature design the higher the RH.

Poor design on large TD will raise vapour pressure and cause higher product moisture losses. Then there is the design of the air movement to consider. (blast/rapid freezing to holding)

Freezing rate and Freezing time are a major factor influencing design. First question I always ask a client and then get them to put it in writing. (Change their minds, like their socks. Then wonder why quote 3 from acme bodgit and legit inc. was cheaper and they have problems:p).

Segei
11-07-2015, 06:11 PM
Look at this discussion http://www.refrigeration-engineer.com/forums/showthread.php?784-Freezer-Humidity

smpsmp45
12-07-2015, 08:21 AM
Many Thanks