# Difference between the various COP formulae

1. Mar 21, 2016

### influx

1. The problem statement, all variables and given/known data

2. Relevant equations
N/A
3. The attempt at a solution
My question is a simple one: how is the above equation for COPref different to the COPref equations I've already encountered (such as COPref = Qc/Win = (h1-h4)/(h2-h1). Is the above just a different form of these? Or is the above only used in specific situations?

Also, one other question. What does ''isostere'' mean exactly? I know isobar means equal pressure and isotherm means equal termperature but can't seem to put my finger on what ''isostere'' means. Wikipedia gives this: https://en.wikipedia.org/wiki/Isostere

But I think that is referring to isostere in a different context?

Thanks

Last edited: Mar 21, 2016
2. Mar 21, 2016

### influx

I edited the above post to include the isostere question but I have now found out that it means constant concentration. However, I can't seem to edit the above post to reflect this hence I decided to post this message.