Freezer Design - Help Needed!

Hi,

I'm trying to source a freezer system and need to estimate the specific heat capacity it must support. How do I calculate the energy (BTUs) and time required to cool down, say water, to a certain temperature, taking into account loss through imperfect insulation?

What is its relationship between the size of the freezer, heat loss through insulation, and the time it will take to reach a steady temperature?

In the end, I need to know whether I've chosen a system of high enough, but not unnecessarily high, capacity for cooling items to about -100C. I have heard that the rate of cooling will not be linear.

Thanks in advance for your help,
Sameer

Quote:

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... capacity for cooling items to about -100C

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Do you really mean -100°C or did you mean -10°C?

Hi Brian,

Yeah it is -100C. It is for an experiment in our lab!

If it is a small quantity why not try using liquid nitrogen or similar as the freezing agent.

Otherwise you are looking at a multi-cascade system to achieve that sort of temperature plus some exotic refrigerants.

Try Revco, they make -80 freezers.

@BRIAN and @joep

Thanks a lot for your response guys. I will look into them and get back if i have any further queries.

@BRIAN
I am curious to know about the exotic refrigerants you have mentioned other than Liquid Nitrogen. Could you please give me their names. Thanks a lot

By exotic I mean that they can be expensive compared to the regular ones.

R1150, R13, R14, R50 eg