Evaporator...

[AndrOvr]

I need your opinion for a evaporator..
this will be for cooling a Peltier 40X40.

[Gary]

The ideal would be to spray the surface which contacts the pelt with the entering liquid refrigerant, keeping that entire surface wet. The leaving vapor would be drawn out from the opposite surface.

Of the options shown, #1 would best achieve this, although none of these are ideal.

Assuming the evaporator is cube shaped, I would extend the entering line to the center of the cube, with the opening slightly flared, the flare pointing towards the surface which contacts the pelt.

[DaBit]

Spraying in the liquid refrigerant in the center of the evap is the most efficient. This way you provide a minimal thermal resistance path to every point of the peltier.

A worse problem is the fact that you need to get rid of a *lot* of heat. Account for peaks up to 450W for a 172W peltier (measured data from my previous peltier system, using a DRIFT-0.8 24V/11A TEC). A 40x40mm sized evaporator won't have enough surface area unless you add a lot of surface-increasing ribbles, holes and pins.