Experiments with Peltier Junctions Pulsed with High Transient Currents

Abstract

It was shown in a previous article by Landecker and Findlay that when transient currents are passed through a cooling Peltier junction the resulting transient temperature depends strongly on the current waveform. In particular, an extremal of the current as a function of time exists for which the resulting transient temperature is much lower than for any other current waveform. With the aid of an experimental method developed for the purpose, temperatures well below 100°K were in fact observed with bismuth telluride junctions. Since the occurrence of temperature transients producing such low junction temperatures is rather difficult to reconcile with some notions of solid-state theory, these results have been reexamined for current densities of up to ∼4000 A/cm2 using a modified technique that eliminates possible sources of systematic errors in the previous method. The results may be summarized as follows. Up to the highest current densities that could be produced a monotonic increase of the temperature drop with final current density was observed. The final temperature drops ranged from 205° to 120° measured from a reference temperature of ∼20°C (room temperature) depending on the efficiencies of the junctions. These efficiencies were difficult to predict from the performance of the junctions with stationary currents. For the highest currents and the very low transient temperatures an error of up to 150° may arise from imperfect heat transfer from the hot junctions to the water-cooled heat sinks unless special probes are provided to measure the Seebeck voltage. It is very likely that the accuracy of the measurements cannot be expected to be improved much further as long as grown crystalline n and p branches are used. It is hoped to produce sintered junctions of more suitable shape and greater mechanical strength for further experiments.

Supercooling of Peltier cooler using a current pulse

“…Early measurements that use the thermoelectric elements themselves as temperature probes [7][8][9] indicate more supercooling than we observed. Results in which a separate thermocouple 6,10 is used to measure the temperature are consistent with our results, but with less detail.…”

“…This transient behavior of a thermoelectric cooler has been studied theoretically [2][3][4][5][6][7] and there is some experimental confirmation. [6][7][8][9][10] Such a cooler could be useful for a device such as a mid-IR laser gas sensor, or any other semiconductor device 11 that needs to be cold for a few milliseconds.…”

Mathematical modeling and optimization of transiant thermoelectric cooling process

“…Факт більш глибокого термоелектричного охолодження в нестаціонарному режимі в порівнянні зі стаціонарним був встановлений вперше в теоретичній роботі Стільбанса і Федоровича [4] та підтверджений подальшими теоретичними [5][6][7][8][9][10] і експериментальними [7,8,11,12] дослідженнями. З фізичної точки зору цей факт пояснюється тим, що ефект охолодження Пельтьє виникає на спаї, а тепло Джоуля в об'ємі віток термоелемента.…”

Periodic heating amplifies the efficiency of thermoelectric energy conversion

“…Relative to a steady-state heat source this approach increases the time-averaged (DT) 2 across the thermoelectric, which as we show here, enhances the conversion efficiency independent of ZT. While the benets of transient operation on thermoelectric refrigeration have been previously considered to achieve lower temperatures [23][24][25][26][27][28] and improved efficiency, 29 limited attention has been given to the efficiency gains possible in a TPG with a transient heat source. [30][31][32] Recent observations by Yamashita et al show that an alternating temperature gradient can improve the conversion efficiency of a TPG, 30,32,33 but a scientic explanation of the design space is needed to optimize this approach for real applications.…”