It is all down to the fact that in normal use the thermocouples of a TEC naturally vibrate, Pressure is required to contain this vibration. With no pressure on the TEC's -
1.) thermal transfer is greatly reduced - the vibration is at a high frequency and with no pressure next to a solid effectively creates a gap. In a
liquid it is obviously not so important but the flow of
coolant past a flat TEC surface isn't going to get much thermal transfer either...the use of copper fins would help enormously.
2.) this vibration can and will over time breakdown the solder joins causing the premature expiry of the TEC. Putting the TEC under pressure reduces the effects of the vibration.
The unit in question doesn't necessary need pressure on the TEC's, the way it is built thermal transfer is carp anyway it couldn't be much worse but it will affect the longetivity of the TEC's life not having pressure. Use of a heat spreader on the hotsides would of enabled more effective heat removal and consequently would of required pressure on the TEC's. If the unit had been built properly and exerted pressure on the TEC's preferably with copper plates it would of been far more effective and worked much better, and of course they could of had fins on the cold plate for the
coolant to pass and done even better !
400 euros for a bit of moulded plastic to support some TEC's really does seem a bit steep and they don't appear to applied any thought as to how well the unit will perform -probably why it is so difficult to get any data.
They are relying on the inexperience of the general population to push this through and get big bucks for little thought and effort.
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