cooling volume

[solgen]

Hi,

I'm new to this forum and not a refrigeration engineer but would like to ask a question which I suspect hasn't got a simple answer!

A warehouse is used to store food at a cooled temperature of 10 degrees C and the electricity consumption for refrigeration is 900,000kWhrs per year. The height of the building is twice that it needs to be and so approximately half the volume of the building is unecessarily chilled. If a false ceiling was introduced the volume of cooling could be halved.

Would it be fair to say the energy consumption to chill this area could be half?

Is there a formula or rule of thumb calculation that can be used to work out the typical energy requirement of the scenario I've described?

Thanks

[chemi-cool]

It will not cut it by half. if a new insulated ceiling in the proper height will be installed, it will help.

Best is to get the services of a consultant engineer to have it checked out.

A cooled hall in the entrance, can save on warm humid air from entering.

[r.bartlett]

It will not cut it by half. if a new insulated ceiling in the proper height will be installed, it will help.

Best is to get the services of a consultant engineer to have it checked out.

A cooled hall in the entrance, can save on warm humid air from entering.

doesn't that just make it a bigger fridge?

[chemi-cool]

No, in most big cold stores where they have high traffic, it is common thing to have like a cooled entrance where products gets colder and drier than out side conditions and after a while, they moved in.its more like a cooled corridor.

[Grizzly]

If you halve the volume then you do reduce (although the chilled product volume is not being reduced!) the initial amount of energy needed to bring that area down to temperature.
But as a result you will also vastly increase the necessary reaction rate of the cooling equipment to the ingress of heat. Introduced as a direct result of the "traffic".
Maintaining a room temperature is easier and cheaper the smaller the fluctuations of temperature within!

A smaller area is not necessarily cheaper to maintain, think of the volume as a form of buffer tank!
Yes smaller areas are easier to control but are also much more susceptible to temperature fluctuations.

I have tried to explain using simple terminology hopefully someone else can elaborate further?
In summary halving the size does not halve your energy consumption and in fact could increase it!
Chemi's point is to reduce the external temp influence on the chilled area.

Things like stock rotation frequencies and their temp on being stored in the warehouse also have huge effects.
Even the type of product being stored has huge ramifications.
I forget the exact formula but it's something like for every 1 degree rise there is a 10% rise in energy consumption!
Think what reducing the chilled volume would do to the amount the temperature rises?


Grizzly

[solgen]

Thank you for your advice - I will indeed consult an expert but just wanted to understand some basic theories first. The fact that the warehouse in question has several loading bays which are open to the elements does suggest that if the height of the building was lowered, the cooling equipment would have to react a lot quicker to the temperature changes caused by external temperature ingress. I would appreciate if someone could add any further info. to this and if anyone can point me at where the 1 degree rise in temp would result in 10% rise in energy consumption. Thank you

[SeanB]

Size really has a small effect on your power use. Reducing heat input by having enclosed bays, staging areas with barrier curtains and changing the forklifts inside to electric will have a bigger effect on your power bill. Training staff not to leave the doors open unnecessarily and placing multiple air curtains to those that have to be open will help as well. Checking for air leaking in as well will help, as well as having a reflective roof that keeps the top cooler helps.