Brendan, before I forget, I believe that there is a "typo" in your Peltier specs.
TES1-12703 should have Imax = 3A and not 2A. The last two digits of the model number represent the Imax in Amps.
I noticed that lots of descriptions of Peltiers on ebay have copy/paste errors, even for the same or for different models. The numbers can, at best, be used as a rough guide. And I am sure that the manufacturers are not telling the truth anyway...
I doubt that a single stage Peltier will get the wanted temperature differential. Few pages back in this thread Patrice had deltaT of 32ºC without sensor with TES1-6303 (3A TEC running at 2A). I don't remember if the Ukrainians got it much better with a single TEC.
Filip got deltaT of 60ºC (see
here) with a custom dual-TEC stack, again running his TECs at 1/2 and 2/3 of max current.
Dual TECs have the maximum deltaT of about 80ºC compared to 60ºC of single modules. That is a 20ºC better starting point. It also means that the TEC does not have to work as hard to achieve the wanted deltaT which means that it is operating in more efficient region. Keep in mind that our heat load is very low.
Looking at power consumption:
Your TEC uses 15.4*2 + 28 = 58.8W of power to remove 28W of heat.
(Or if I am correct and it is 3A than it uses 74W)
TEC2-19003 (which I mentioned few posts back) uses 16*3 + 15 = 63W of power to remove 15W of heat.
For 2A case the TEC2-19003 is only 5W more power hungry but it is more efficient for our purpose and optimised to get bigger temperature differential. This is what we are after.
That's why I liked the TEC2-19003 and will order one tonight to do some tests.
Also it is difficult to compare each other tests as everybody is using different heatsinks/heat loads/fans/power etc.