researchers from yale, princeton, and mit have combined efforts to determine the upper bounds of radiative heat transfer between near-field bodies and concluded that the increased radiation rates they found showed significant room for improvement in designs, particularly for thermophotovoltaic cells.

this research could have a major impact on solar cells like the one above. (wikimedia commons)

radiant heat exchange is a transfer of electromagnetic energy from a warm body to a cooler one, but the stefan-boltzmann law describes a limitation to the maximum radiation that can emanate as well as the maximum heat transfer rate.

the researchers examined this concept at a nanoscale, where blackbodies (the ideal for radiant heat transfer) are no longer applicable because at those tiny distances bodies will emit frustrated evanescent energy. while this effect has already been studied in the past, the research was limited by the need for symmetric structures.

so, the researchers set out to determine the maximum rate in the near-field regime dependent only on the material properties and the distance between the bodies by focusing on the total stored energy of the evanescent field near the emitter.

the study found that the bounds of near-field radiant heat transfer were much higher than previously thought, although there will be design challenges to take full advantage of this.

the researchers noted, “it has only recently become possible to calculate radiative heat transfer between non-planar bodies (and experimental tests are similarly recent), but the promise of potential improvement by using suitably patterned surfaces may provide the necessary impetus for further computational, theoretical, and experimental studies with the aim of ultimately achieving an ideal near-field thermal radiator.”

read the full article at http://spie.org/newsroom/6706-fundamental-limits-to-near-field-radiative-heat-transfer#b13.