Strained PbTe Shows Strong Thermoelectric Properties

[sanman]

Apparently, strained nanocrystals of PbTe are able to achieve a high thermoelectric figure of merit, for improved thermoelectric conversion efficiency:


http://www.eurekalert.org/pub_releases/2011-01/nu-bic011811.php

http://www.nature.com/nchem/journal/v3/n2/abs/nchem.955.html


So if this is expected to result in 14% efficiency in conversion of waste heat to electricity, then what kind of applications would most benefit?

Also, if these improved thermoelectric properties can boost efficiency of conversion of heat to electricity, shouldn't there also be reciprocal benefits in thermoelectric cooling - ie. using electric current to directly drive a heat pump?

 

[jsgruszynski]

Apparently, strained nanocrystals of PbTe are able to achieve a high thermoelectric figure of merit, for improved thermoelectric conversion efficiency:


http://www.eurekalert.org/pub_releases/2011-01/nu-bic011811.php

http://www.nature.com/nchem/journal/v3/n2/abs/nchem.955.html


So if this is expected to result in 14% efficiency in conversion of waste heat to electricity, then what kind of applications would most benefit?

Also, if these improved thermoelectric properties can boost efficiency of conversion of heat to electricity, shouldn't there also be reciprocal benefits in thermoelectric cooling - ie. using electric current to directly drive a heat pump?

The biggest problem with thermoelectric devices is the inability to scale to high energy transfer densities. That is, you can move heat efficiently over distance but only so much energy per unit area (per time) of heat flux (rate) and per unit volume heat density.

This is mostly due to being solid state: there are upper bounds to have fast you can transfer heat in any solid, compared to fluid heat transfer. In terms of moving heat over a given distance, other technologies like heat pipes tend to be more scaleable. But heat pipes have limits as well. At some point you need to actively pump the working fluid as a conventional refrigeration system. And then that has limits as well.

The efficiency effects are generally reciprocal for cooling and heating but the same issue of energy density is still a problem. As long as the amount of heat per unit volume you want to move is fairly small, thermoelectric works great and adding efficiency allows applications that fit it to use less power to do the same thing.