I'm looking to buy a freezer for doing a -10C lifetime test on a product that generates 175W. What I want to do is calculate the available cooling capacity for potential refrigeration units, given their input power and COPs.

My current modeling approach is basically a constant temperature reservoir (ambient), a cyclic machine, and a fixed volume of air. I've got an expression for the cooling power in terms of the input power to the cyclic machine, the thermal mass of the volume, temperatures, and entropy generation.

I imagine to calculate the margin I have in terms of cooling capacity, I need to know what my entropy generation (and subsequently, exergy destruction) is. I'd have to think that this is tied to the COP of the system, so is there a way to calculate this exergy destruction from the COP?

Also, if my approach is wrong, please let me know.

Thanks all