The transient behavior of Peltier junctions pulsed with supercooling

Abstract

There exists the transient thermoelectric supercooling effect that can be enhanced by keeping on increasing the Peltier cooling effect to compensate for the Joule heating effect and Fourier heat conduction effect arriving at the cold junction, in which a transient cold spike can be produced by superimposing an additional shaped current pulse of a large magnitude on the original steady-state optimum value. Most previous work on the transient supercooling mainly focused on the minimum supercooling temperature achievable and separately analyzed the beneficial or detrimental effects on the transient supercooling performance, which was not clarified quantitatively to what extent the interactional effects were on the enhancement of the transient supercooling performance. In this work, we systematically investigate a numerical solution involving time-dependent imposed voltage pulse and time-dependent thermal boundary conditions on the transient supercooling behavior as well as the response of characteristic time and cold-junction temperature distribution to the pulse operation parameters during the periods of pulse start-up, pulse-on time, and pulse-off time, which is served as a theoretical basis for exploiting the coupling interaction of the thermoelectric effects on the heat diffusion from or to the cold junction interrelated with the amount of the availably electrical conversion in the short time scale. Additionally, the advantage of certain pulse forms over others is described. The results indicate that Peltier supercooling capacity shows a decreasing monotonic trend in proportion to the total amount of electrical conversion, and the maximum coefficient of performance for cooling state is about 0.5 to be achieved at steady state. Taking advantage of the temporary Peltier effect focused electrical conversion as the additional cooling for a period long enough against the earlier arrival of the excessively Joule heating dominated heat accumulation is the key parameter for the significant level of thermal enhancement on the pulse supercooling. The discussions may be attractive for compact thermal system coupled with pulsed Peltier supercooling to come up to the localized cooling level of high power packaging.

Optimization of supercooling effect in nanoscaled thermoelectric layers

“…It has been shown that by applying a quadratic pulse form, the supercooling effect can be improved over other forms [7]. Some other pulse forms present additional advantages [8], [9]. Here we explore the influence of the electric pulse shape in the supercooling effect when the dimensions of the thermoelectric device goes to the submicrometer length scale.…”

Rotating thermoelectric device in periodic steady state

“…Such transient modes are constantly attract the attention of researchers [5,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] because such modes have advantages over the stationary steady state. For example, at certain times in a pulsed cooling mode [24][25][26][27][28][29] deeper cooling can be reached.…”

“…Higher current passed through the TE device for a short time delivers additional cooling. Optimization of length and shape of the current pulses can give deeper cooling on limited time intervals [27] or the cooling of small objects in a shorter time [28,29].…”

“…In transient modes, the efficiency of TE device is affected by many other parameters such as the temperature diffusivity, the current pulse duration in a pulsed mode [6,[24][25][26][27][28][29], the relaxation time of thermal processes etc. Such transient modes are constantly attract the attention of researchers [5,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] because such modes have advantages over the stationary steady state.…”

Peltier Supercooling with Isosceles Current Pulses: A Response Surface Perspective

“…19 Variables that affect pulsed Peltier cooling include: thermoelement length, 15 current pulse amplitude 15,19 pulse duration, 19 pulse shape, 14,16,19,[22][23][24][25][26][27] time between pulses, 28 thermoelectric figure of merit, 15 thermoelement thermal diffusivity 15 , thermoelement shape [29][30][31] and the number of stages of a multi-stage thermoelectric cooler. 32 Of these variables, there are only two that can be varied to change the operating conditions for any given pulse shape.…”