# Methodological Considerations of Using Thermoelectrics with Fin Heat Sinks for Cooling Applications
## 3 Results and Discussion
* As a result, the temperature difference between hot and cold sides (\(T_{h}-T_{c}\)) increase with applied TE voltage (\(V_{te}\)). * At low TE applied voltage (\(V_{te}\)), the TE cold side (\(T_{c}\)) could be higher than the hot side (\(T_{h}\)). This is because of the insufficient TE power supply to generate a sufficient temperature differential to enable the TE to function. Figure 8: Transient temperatures for the FHS-TE assembly (FC (forced convection), \(P_{EH}\) = 10 W, Run D3). Figure 10: Comparison of interface temperatures for the FHS-TE assembly (NC and FC, \(P_{EH}\) = 10 W, Runs D1 and D3). Figure 9: Transient temperatures for the FHS-TE assembly (FC, \(P_{EH}\) = 20 W, Run D4). A comparison between experimental and predicted TE hot side temperature (\(T_{h}\)) is shown in Figure 12 at different power inputs (\(P_{EH}\)) and under NC and FC modes. It can be seen that the hot side temperature increases with both the heat source and TE power inputs. It is also higher under theNC air flow condition. The predicted values are lower than experimental values by less than 2 \({}^{\circ}\)C or about 2%. Keeping in mind that the experimental accuracy of the thermocouples is about +0.5 \({}^{\circ}\)C, the agreement between experimental and theoretical is extremely good. The experimental coefficient of cooling performance (CO\({}_{c}\)) and temperature difference across the TE module (\(\Delta T_{te}\)) are compared in Figure 13 at various power inputs to both the heating element (\(P_{EH}\)) and the applied voltage (\(V_{te}\)) to the TE and also under NC and FC cooling modes. It can be seen that the temperature difference increases while COP\({}_{c}\) decreases with TE power input. The NC air flow results in a higher temperature difference and COP\({}_{c}\). A higher COP\({}_{c}\) and lower temperature difference are obtained at higher heat source power input. Figure 11: Comparison of interface temperatures for the FHS-TE assembly (NC and FC, \(P_{EH}\) = 20 W, Runs D2 and D4). Figure 12: Comparison of experimental and predicted \(T_{h}\) for the FHS-TE assembly. Figure 13: Coefficient of performance COP\({}_{c}\) and temperature difference \(\Delta T_{te}\) for the FHS-TE assembly. The effects of employing a TE module for cooling is shown in Figure 14, which compares the surface temperature of the aluminium block (\(T_{alm}\)),with and without the TE module under NC and FC conditions, at 10 W and 20 W power inputs (\(P_{EH}\)), and with various applied TE voltage (\(V_{te}\)). The values shown in dashed lines represent the temperature (\(T_{alm}\)) obtained without the TE while the solid lines show the results obtained with the FHS-TE assembly. The temperature of the surface of the aluminium block is about 1-2 \({}^{\circ}\)C lower than the heating surface temperature (\(T_{s}\)). The results show the following:  
* The surface temperature of the aluminium block is higher under NC when compared to FC, as expected, because of less efficient cooling. * Lower power input (\(P_{EH}\)) results in lower temperature. * Under the NC cooling mode, the temperature is lower without the use of the TE at both TE applied voltages (\(V_{te}\)) of 10 W and 20 W.
* In other words, the use of the TE module is not effective under the NC cooling mode. The heat transfer resistance of the TE module has a negative effect on the natural heat loss. Under the FC cooling at 20 W, the applied voltage (\(V_{te}\)) to the TE module should be \(>\)4 V and at 10 W, it should be \(>\)1 V.