Hypothetical COP value...

[zig]

Hi everyone,

I'm currently taking an intro to Chemical Thermodynamics course and we are working on a little project for the class.

Here is the assignment:
" Design an ideal Rankine refrigeration cycle that will maintain a restaurant walk-in cooler at 30 degrees F. Assume that the refrigerantR227(Heptafluoropropane) is your working fluid and that your cycle includes a joule-Thompson expansion process."

My question doesnt really regard to it being rankine or anything about joule-thompsion. My question is in regards to (COP) values. I attempted googling values of refrigerators to compare and design around, but to no avail. Any helpful ideas of what COP values i should be expecting or where to look. I'm very new to this so any advice would be awesome. Thanks!

[BigJon3475]

Download this free standard (http://www.ari.org/ARI/util/showdoc.aspx?doc=9)

Search for COP


I don't know if that will help you or not I may be misunderstanding your question.

[Peter_1]

These give you and idea http://www.aie.org.au/melb/material/resource/cop.htm and here some explanation
http://en.wikipedia.org/wiki/Coefficient_of_performance
http://www.ochsner.com/funktion.htm

A walk in cooler with a Rankine engine, working on r227..!!??
I bet your prof never saw a walk in cooler in real life.
They should give you questions which reflects the real life.
A Rankin cycle isn't used in real life for cooling purposes.
A Joule Thompson cycle is used in jet aircrafts for the airconditioning, known as a Air Cycle Machine (ACM)

[taz24]

Hi everyone,

Any helpful ideas of what COP values i should be expecting or where to look. I'm very new to this so any advice would be awesome. Thanks!


Hello.

The COP value is as you know just a figure of efficiency. If the COP value was 1 then for every unit in energy used you would get the equivalent unit out as work done.

Most fridge systems are deemed efficient if they are about 3. An efficient heat pump will give a value of 4.
Some manufactures will give higher figures but they are tending to manipulate the data to prove there system is more effiecient than the compatition.

So in short an efficient system would be in the region of COP 3 to 1 or COP 4 to 1.


Cheers taz.

[powell]

Hi everyone,
I attempted googling values of refrigerators to compare and design around, but to no avail. Any helpful ideas of what COP values i should be expecting or where to look. Thanks!

I agree with Peter_1, "They should give you questions which reflects the real life"

Anyway, here are a couple links to manufacturers who build conventional refrigeration equipment that have designed a system that is more energy efficient.

The first is Heatcraft and their Beacon II system:
http://www.thecoldstandard.com/products/overview.asp?pid=29

Next is Russell's Sierra system.
http://www.russellcoil.com/html/technolo.htm

Regards.................Powell