# Methodological Considerations of Using Thermoelectrics with Fin Heat Sinks for Cooling Applications
## 3 Results and Discussion  
Figures 6 and 7 show the transient temperatures recorded for the hot (\(T_{h}\)) and cold (\(T_{c}\)) sides of the TE and also for the heat source (\(T_{s}\)) surface temperature at a power input (\(P_{EH}\)) of 10 W and under NC. The following results are observed:  
* Temperatures of \(T_{h}\), \(T_{s}\), and \(T_{c}\) are plotted for the first 120 min and, every 60 min thereafter. The results showed that steady state is achieved after 2 h at the low TE voltage run of 1 V while it took only about an hour at the higher TE voltage >2 V.
* Heat source temperature (\(T_{s}\)) is higher than cold side temperature (\(T_{c}\)) by about 1 \({}^{\circ}\)C. This was attributed to the temperature diffference across the thin aluminum block, calcualted to be around 1 \({}^{\circ}\)C.
* Temperature difference between hot and cold sides of the TE (\(T_{h}-T_{c}\)) is about 36 \({}^{\circ}\)C at the low-power input of 10W and about 12 \({}^{\circ}\)C at the higher power input of 20W. Temperature difference decreases with TE power input (\(P_{te}\)). * Heat source temperature (\(T_{s}\)) increases with power input (\(P_{EH}\)) from 73 \({}^{\circ}\)C at 10 W to 104 \({}^{\circ}\)C at 20 W.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**NC/FC**} & \multirow{2}{*}{**Run \#**} & \multirow{2}{*}{\(P_{EH}\) (**W**)} & \multirow{2}{*}{\(V_{w}\) (**A**)} & \multirow{2}{*}{\(I_{te}\) (**W**)} & \multirow{2}{*}{\(P_{w}\) (**A**)} & \multirow{2}{*}{\(T_{s}\) (**W**)} & \multirow{2}{*}{\(T_{c}\) (**A**)} & \multirow{2}{*}{\(T_{s}\) (**A**)} & \multirow{2}{*}{\(T_{h}\) (**A**)} & \multirow{2}{*}{\(\Delta T_{w}\) (**A**)} & \multirow{2}{*}{\(T_{m}\) (**A**)} & \multirow{2}{*}{COP\({}_{r}\) (**A**)} \\  & & & & & & & & & & & & & & \\ \hline \multirow{8}{*}{NC} & \multirow{8}{*}{D1} & 10.1 & 1.01 & 0.52 & 0.52 & 20.6 & 65.7 & 64.7 & 64.8 & 0.1 & 64.8 & 19.34 & 63.8 \\  & & 1  
Figures 8 and 9 show the transient temperatures recorded for the hot side (\(T_{h}\)), cold (\(T_{c}\)) side, and heat source (\(T_{s}\)) under FC power input (\(P_{EH}\)) of 10 W and 20 W, respectively. The following results can be seen:  
* Steady-state is achieved earlier under FC compared to NC, i.e., after about 30 min, compared to 120 min and 60 min under NC. * Heat source temperature (\(T_{s}\)) is higher than the cold side temperature (\(T_{c}\)) by about 1 \({}^{\circ}\)C. A similar difference is observed under NC showing that the contact thermal resistance does not change with convection. * Cold side temperature (\(T_{c}\)) decreases with an increase in TE applied voltage (\(V_{te}\)) as expected. * The temperature difference (\(T_{h}-T_{c}\)) between hot and cold sides increase with TE applied voltage (\(V_{te}\)) as expected. * Heat source temperature (\(T_{s}\)) was brought below, or to, ambient temperature (\(T_{a}\)) when power input (\(P_{EH}\)) to the heat source was at 10 W and TE input voltage (\(V_{te}\)) was at 6 V.
* Heat source temperature (\(T_{s}\)) roseqo about 40 \({}^{\circ}\)C when the heat source power input (\(P_{EH}\)) was increased to 20 W.
* The temperature difference between TE hot (\(T_{h}\)) and cold (\(T_{c}\)) sides was lower at the higher power input of 20 W, comapred to 10 W.  
Figure 6: Transient temperatures for the FHS-TE assembly (NC (Natural convection), \(P_{EH}\) = 10 W, Run D1). Figure 7: Transient temperatures for the FHS-TE assembly (NC, \(P_{EH}\) = 20 W, Run D2). Interface temperatures (\(T_{h}\), \(T_{c}\), and \(T_{s}\)) under NC and FC conditions and heat source power input (\(P_{EH}\)) are compared in Figures 10 and 11. The results show that:  
* All temperatures are lower under FC cooling because of higher cooling heat transfer rates during FC air cooling mode as expected. * Hot side (\(T_{h}\)) temperatures increase with an increase in the applied TE voltage (\(V_{te}\)). * Cold side (\(T_{c}\)) temperatures decrease with an increase in the applied TE voltage (\(V_{te}\)).