Page 142 - Introduction to Transfer Phenomena in PEM Fuel Cells

– h is the convective transfer coefficient calculated from the Nusselt
g
–2
number, in [W.m .K ].
k –1 Heat Transfer Phenomena 131
h = Nu ⋅ d h [4.12]
g
The Nusselt number depends on the channel geometry, the Reynolds
number and the Prandtl number for a laminar flow.

4.2.4. Energy balance for the solid structure

The energy balance of the solid structure of the stack describes the
conduction of heat, heat by convection (which is transmitted from the flow
channels to the solid structure), and the reaction enthalpies occurring in the
source terms [SRI 06]:


1 ⋅  h ⋅ B ⋅ T − T ) − 1 Δ H + V ⋅ J K ∂ 2 T s = 0 [4.13]
+

⋅

s g g ( g s s ne F   x ∂ x²
g
where K being the effective thermal conductivity of the solid structure,
x
with:
 K ⋅δ h
h
K = h  δ [4.14]
x
h h

4.3. The heat flow in the different layers of the PEMFC

The heat flow density generated by the electrochemical reaction in the
anodic catalytic layer is given by [CHE 05]:

 Δ H − Δ G a 
j η −
q ACL =⋅  a a  [4.15]
 nF 