Internal Heat Exchanger (Evaporator)

Dear all,

There is a lot of theory on increasing the evaporating temp. by 1deg C and getting noticeable increase in refrigeration system COP. I have done the calculations and it is certainly true in theory.

Is it as straight forward in reality if an internal heat exchanger IHX is combined with the evaporator of a single stage vapour compression system, to get higher evaporating temps.?

Can someone point me in the right direction to find useful info. on IHX's and how their size relates to the heating effect of the refrigerant?