Critical Space Temperature Rise Over Time During A Power Outage

[mbelz]

What program would you recommend our how would you go about calculating the temperature rise of a cold storage facility during a power outage on a design day? Assume the power outage would cause the HVAC / lighting / room equipment to be off and the outside air and exhaust air dampers to be closed.

 

[mbelz]

Note: I am trying to determine how long it will take for the space temperature to rise 5 degrees F.

 

[urgross]

Since I don't own HAP or TRACE, I'd probably use Energy Plus.

 

[MintJulep]

I would likely use the program called "hand calculation".

 

[SAK9]

Mint you stole my thunder.Unfortunately no programme will help you solve this problem.The programme may help you calculate hourly heat gains into the space.Using the heat gain as the input and treating the room air volume and product as the mass being heated you can approximately calculate the temperature rise in a given amount of time.What good is going to come out of this calaculation?

 

[willard3]

You're going to do this by hand.

 

[urgross]

Maybe I misunderstood, as I have worked on cold, dry storage facilties before, to include mission critical and anticipated requirements for contingenercy emergency power.

While you may want to do hand calculations for envelope, amount of temperature rise will depend heavily upon ambient conditions and the storage contents and their temperature. I've seen this same question asked in customer meetings with the COE when they needed to have a contingency contract for an 18-wheeler to drive up within a specified time frame for emergency power and 4 days operating fuel. Perhaps picking out worst case, say July 19 at 1500, and only thing left in cold storage is mission critical only (such as as panedemic supplies included with MTOE deployables). This is not a routine or simple solution, at least if that is the case.

Most surprsing is that the cold, dry storage facilties would be suppled with only EEC power, not full back up.

 

[Timothi]

Heat energy required for temp rise = Total room volume x density of air x specific heat capacity of air x(final temp - initial temp)

time required for temp rise = Heat energy/Heat load

Sharing knowledge is the best way to learn

 

[Compositepro]

Almost all the heat (or cold) storage capacity is in the stored materials and structures inside the insulated space, and not in the air. Also, unless fans continue to stir the air, material stored at the top of the room will thaw long before materials at the bottom.

 

[chicopee]

This is a tough case to figure out because you must make a decision on how much stock you have in the room and balance that with the amount of insulation you are willing to install in order to maintain a certain amount of temperature before food spoilage. So to be prudent, you will note that supermarkets and wholesale stores have backup generators, otherwise insurance companies may back up on providing food spoilage coverage or exclude that provision.