Environmental Engineering Reference
In-Depth Information
leave the metal with a lower work function and travel to the metal with a higher
work function.
6.3.1.4 Temperature Dependence of the Thermal Conductivity
at Interfaces
In this particular case the recti
cation is based on the difference in the temperature
dependence of the thermal conductivity between two materials (see Fig. 6.14 )
6.3.2 Molecular-Nanoscale Mechanisms
Non-uniform mass loading
Non-uniform deposition of mass on nanotubes. See above in the text by Chang
et al. [ 80 ]. The higher thermal conductivity is observed in the direction of high-
mass to low-mass.
￿
Asymmetric nanostructured geometry
Most applications relate to carbon, boron nitride nanotubes, asymmetric
graphene sheets, carbon nanocones or nanohorns [ 72
￿
74 , 83
86 ].
-
-
Nanostructured interfaces
Thermal transport at solid
￿
solid interfaces and related effects.
-
Anharmonic/non-linear lattices in 1D chains
A thermal recti
￿
er using a nonlinear 1D lattice and connecting it to two thermal
reservoirs at different temperatures [ 74 , 87 ].
Quantum (active) thermal systems
￿
cators do not represent some
extraordinary features for the thermal diode mechanism. The effect of the so-called
recti
Generally, passive solid-state thermal
recti
cation is low and is limited to large temperature gradients, and the effect itself
is not in terms of an order or larger. However, we should not forget that this is an
emerging and rapidly developing domain, which can perhaps bring nanostructured-
built-up-to-bulk materials with very high recti
citation effects in the future.
6.4 Micro Fluidic Thermal Diodes
In this subsection we present micro
uidic mechanisms that can be applied as
thermal diodes in magnetic refrigeration. Micro
fl
fl
uidics is a new interdisciplinary
domain involving many different scienti
c
elds. In our particular case we will refer
to micro
uidic systems, which incorporate electrical engineering, mechanical
engineering and physics. These systems further refer to the domains of electrohy-
drodynamics, ferrohydrodynamics, magnetohydrodynamics, and a special domain
of electro- and magneto-rheology.
fl
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