Question about a heat transfer/fluid dynamics problem

[sdusheyko]

I have to theoretically design a 'pad' which would, in room temp conditions (~300K), have a surface temp of around (~290K). so just imagine basically a cold rectangle.

since i want the most heat flux just at the top surface of this box i would use materials with poor thermal conductivity on the sides (plastic) and sheet al or steel for the top surface (cold surface).

my plan is to basically circulate water through this pad via ice water reservoir (~276K inlet temp.) the thing is, surface temp sure be as uniform as possible which is something I'm having trouble with in my design (rough sketch provided).

the red lines represent invisible lines. the only time i use invisible lines is to indicate the divider. fluid flow indicated with arrows.

my biggest problem is that there is no way the surface temp is going to be const according to my heat trans theory.

this may be a long shot; any suggestions on the theory or design? thanks!

 

[sdusheyko]

:/ ..

 

[sdusheyko]

so i think I've come up with an acceptable solution (compromise).

I'm going to add a temperature strip to the top surface so that the practitioner can chose which part of the gradient is most suitable for hir experimentation.