Thermoelectric Device Enhancement of Heatsink Performance 1
Introduction � Thermoelectric devices as heat sink enhancement � Thermoelectrics are often treated as commodity components – little thought devoted to proper sizing � Optimization techniques are not often practiced 2
Thermoelectricity Heat Absorbed p-Type Semiconductor Positive (+) n-Type Semiconductor Electrical Conductor (Copper) Electrical Insulator (Ceramic) Negative (-) Heat Rejected 3
Typical thermoelectric system 4
Problem – designing a thermoelectric into an application I 2 ρ ( ) Q = 2 N α IT − − κ T − T C C H C G 5
Problem – designing a thermoelectric into an application 6
� Since T H and T C are unknown, Q C and Q H are also unknown � From the Q C equation, N and G are not yet known I 2 ρ ( ) Q = 2 N α IT − − κ T − T C C H C G 7
Existing methods � 8
Development of Method Assumptions Q C , T C , θ , and I are predetermined � Cold side thermal resistance is to � be ignored 9
2 α ( ) κ G T − T 1 + 1 + T H C ave ρκ I = OPT α T ave I α T G = OPT ) ( ave ) ( OPT κ T − T 1 + 1 + ZT H C ave T = T + Q θ H amb H 10
Q N = C OPT 2 I ρ 2 α I T − − κ ∆ TG ) OPT OPT C OPT 2 G OPT V = IR + 2 N α ∆ T Q = Q + P H C Then solve for a new T H and start another iteration, solving for G OPT and N OPT . 11
Q: Will a thermoelectric be an enhancement in my application? The iteration method provides the best possible TED – if this does not work, then a thermoelectric solution is not feasible with for this application. 12
Results 13
14
Thermal Resistance vs. T C 80 70 60 T C (°C) 50 Tc, heat sink without TED 40 Tc, 3.5A Tc, 4A 30 Tc, 8A 20 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Heat sink thermal resistance (°C/W) 15
Conclusion � Method for determining an optimized thermoelectric solution for a given application. � Method determines the number of couples and geometry of thermoelectric elements. � Comparison made for TED-enhanced heat sink against non-enhanced heat sink. 16
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