Transient Heat Transfer Characteristics Of Thermoelectric Cooler And Application Study

Advanced thermal management technology is urgent needed as the rapid development of highly integrated electronic devices.The thermoelectric transient supercooling is expected to significantly suppress temperature rise in electronic devices since it has the advantages of ultra-fast response rate and large cooling density among various refrigeration techniques.However,the previous work on thermoelectric cooling technology mostly focused on how to improve the cooling efficiency in steady-state mode,and most of the research on transient supercooling laws and optimization characteristics focused on theoretical studies.The real situation is very different from the theoretical model.Many problems need to be solved,such as the actual influence law of thermoelectric performance parameters on transient supercooling,the actual loss percentage of interface effects on transient supercooling,etc.In addition,a complete control strategy for thermoelectric devices in transient operation has not been formed yet,which seriously restricts the wide application of transient supercooling.Based on above problems,this work focuses on thermoelectric transient heat transfer and then systematically investigated the following three ways:i)The transient calculation model of thermoelectric integrated system is developed,using theoretical calculations and experimental methods,we systematically investigated the impact of intrinsic properties and interface contacts on thermoelectric transient supercooling.It can be found that the thermoelectric materials with the same z T value but larger power factor can obtain lower cooling temperature in steady-state mode and have faster response and better ability to suppress temperature overshoot in transient mode under large thermal load,but their overall transient benefits are almost equal.In addition,both interface effects lead to severe supercooling losses.Through theoretical calculations and experimental methods,it can verify that thermal contact resistance has a greater impact on transient supercooling than electrical contact resistance under similar interface contact ratio conditions.ii)The complete control strategy for a thermoelectric device in transient operation mode was firstly set up by us,which also was verified the temperature control effect at short-time oversized thermal load.The results show that the composite control strategy consisting of PID control,transient pulse control and feedforward control can trigger transient supercooling and achieve over-regulation to suppress temperature rise in advance,resulting in substantial improvement of thermoelectric temperature control accuracy and stability,which is significantly better than previously reported values.iii)The thermal conductivity measurement technique of transient photo-electro-thermal（TPET）was developed,and the accuracy and applicability of the TPET technique for measuring the thermal conductivity of thermoelectric films were investigated by combining theoretical calculations and experiments.The TPET technique using laser beam heating can significantly reduce the influence of Peltier transient heat transfer effect,and the measurement uncertainty of TPET technique for TE films can be depressed below 10%,thus achieving high test accuracy.Furthermore,this method is not only applicable for free-standing thin film,but also for thin film deposited on as-known substrate.Finally,thermal conductivity of several films including p-type Bi_0.5Sb_1.5Te₃,n-type Ag₂Se,and n-type Bi₂Te₃deposited on PI film are accurately measured,which demonstrates the wide applicability of TPET technique on the thermal conductivity measurement of thermoelectric films.