Multistage Thermoelectric Coolers Research Articles

Performance analysis of four-stage thermoelectric cooler for focal plane infrared detectors

A cooler provides a low-temperature working environment for refrigerated infrared detection chips and is an indispensable component in infrared detectors that ensures their smooth operation. In this paper, a thermodynamic model of a heat-pipe-type four-stage thermoelectric cooler with a large temperature difference applied to a focal plane infrared detector is constructed. The heat leakage of the detector is calculated using the model. The performance indexes of the coordination performance coefficient and module utilization coefficient are used to unify the cooling capacity and economic performance of the device. The impression of the working current, heat pipe parameters, and cross-sectional area of the thermoelectric leg on the performance of cooler are analyzed. A Pareto optimal solution is obtained using an NSGA-II algorithm and TOPSIS decision. A low cooling temperature is obtained using a multistage thermoelectric cooler to achieve a large cooling temperature difference. When the working current is 5.65 A and the cross-sectional area is 4.5 mm2, the maximum cooling temperature difference reaches 110.6 °C, and the lowest cooling temperature reaches -83.6 °C. When the working temperature of the detector is -60 °C, the current and cross-sectional area corresponding to the optimal solution of cooling capacity-COP-power consumption are 1.51 A and 2.74 mm2, respectively.

Multi-Stage Thermoelectric Coolers Current Optimization for Infrared Detectors Based on the SNOPT-Finite Element Method

At present, series power supply has been widely used in multi-stage thermoelectric coolers (TEC), however, the series power supply cannot fully utilize the full cooling capability of multi-stage TEC. In this paper, according to the actual working conditions of IR detector coolers, three multi-stage TEC models with different numbers of stages were established, and a new method of SNOPT-FEM coupled analysis was adopted to individually optimize the current of each stage. The method considers the synergistic influence of inter-stage thermoelectric effects, which makes the simulation results closer to reality and improves the model solution efficiency with the help of algorithms, which shortens the computation time by at least 46%. The results show that the cold side temperatures of 3-stage, 4-stage, and 5-stage thermoelectric coolers with separated and separated algorithmic power supply can be reduced by 7.95 K and 8.59 K, 8.20 K and 9.04 K and 8.37 K and 9.13 K, respectively, compared with the series power supply. The large cooling temperature difference under separated and separated algorithmic power supplies was achieved at the expense of more power consumption and lower COP compared with the series power supply. Therefore, high-power sources are required to meet the cooling needs of IR detectors in engineering applications. It is thus evident that the proposed method is favorable to promote the application of thermoelectric cooling in infrared detection.

Hierarchical Low-Temperature n-Type Bi2Te3 with High Thermoelectric Performances.

The high performance of a multistage thermoelectric cooler (multi-TEC) used in a wide low-temperature range depends on the optimized thermoelectric (TE) performance of materials during the corresponding working temperature range for each stage. Despite decades of research on the commercial TE materials of Bi2Te3, the main research is still focused on temperatures above 300 K, lacking suitable hierarchical low-temperature n-Bi2Te3 for multistage TEC. In this work, we systematically investigated the influence of doping concentration and matrix material compositions on the TE performance of n-Bi2Te3 below room temperature by the high-energy ball milling and hot deformation. Consequently, two hierarchical n-Bi2Te3 materials with excellent mechanical properties working below 248 and around 298 K, respectively, have been screened out. The Bi2Te2.7Se0.3 + 0.03 wt % TeI4 can be adopted in a low-temperature range that exhibits the high average figure of merit (zTave) of 0.61 within 173-248 K. Meanwhile, the Bi2Te2.7Se0.3 + 0.05 wt % TeI4 sample displays a competitive zTave of 0.85 within 248-298 K, which can be applied above 248 K. The research of hierarchical TE materials provides valuable insights into the high-performance design of multistage TE cooling devices.

Numerical study on infrared detectors cooling by multi-stage thermoelectric cooler combined with microchannel heat sink

Lightweight, noiseless, and constant low-temperature refrigeration is crucial for cooled infrared (IR) detectors, especially short-wave-infrared (SWIR) detectors. However, some SWIR detectors, such as HgCdTe photovoltaic detectors are working below 210 K. For this application, multi-stage thermoelectric coolers (TEC) are preferable to single-stage thermoelectric coolers because they can generate larger temperature differences. This paper presents a refrigeration design that integrates SWIR and TEC into a vacuum Dewar package and combines them with a microchannel heat sink (MHS) to improve the detection performance and better responsiveness of SWIR. Two different refrigeration models, SWIR + TEC + AHS (air-cooled heat sink) and SWIR + TEC + MHS, were established to evaluate the refrigeration performance of the proposed SWIR + TEC + MHS scheme using the finite element method. The influences of multi-stage TEC leg length and current, inlet water temperature, and water velocity on the refrigeration performance of the TEC are analyzed. The results show that the SWIR + TEC + MHS design scheme has the best comprehensive performance and minimum volume. The influences of all the factors are obvious while the current has the most important effect on the performance. The temperature of SWIR reached 201.69 K at standard working conditions. It shows that the cooling scheme can not only meet the needs of flexible deployment of SWIR but also provide better thermal security. The proposed cooling design has an excellent prospect for short-wave-infrared detectors.

Performance Analysis of Multistage Thermoelectric Cooler with Water-Cooled

A finite time thermodynamic model of the multistage thermoelectric cooler with constant temperature heat source and water-cooled is established, and the calculation method of input power and coefficient of performance (COP) are given. The influence of key parameters on device performance under different working conditions is given. The effects of the working current and cross-sectional area of the thermoelectric unit on refrigerating capacity, COP, thermodynamic perfection, module utilization coefficient, and coordination performance coefficient are analyzed. The results show that there are optimal working currents and optimal cross-sectional area, which can make the performance of the device reach the best. The evaluation index also provides a reference for realizing different goals and optimization.

Multi-stage thermoelectric coolers for cooling wearables

• Multi-stage TECs are shown to perform better than single-stage TECs for use against skin. • Multi-stage TECs can achieve lower temperature, while maintaining power requirement. • Results are validated using experiment, finite element analysis and analytical solutions. Over the last decade, there has been significant interest in the use of thermoelectric coolers (TECs) in cooling wearables. While there has been notable work on optimizing single-stage TECs for use against human skin, much less attention is given to multi-stage TECs. In this contribution, analytical computations are performed to show that multi-stage TECs can achieve lower cold side temperatures while maintaining the coefficient of performance as compared to single-stage TECs when used against human skin. The findings are confirmed with detailed FEA analysis and experiments. The results therefore imply that multi-stage TECs have the potential of providing more cooling sensation to the human skin, while maintaining the power required per unit cooling power provided. This paper provides a detailed parametric studies on how key design parameters of the TECs (number of stages, current ratio, fill factor, aspect ratio and leg area) affect the performance of the multi-stage TECs. A guideline on the optimal design parameters is provided to guide the design of multi-stage TECs for use in cooling wearables.

Design and optimization of a cubic two-stage thermoelectric cooler for thermal performance enhancement

Low-temperature condition is highly required in many fields, such as aerospace, medical devices, and electronic components. The development of devices to provide low-temperature condition is of great significance. In this work, a novel cubic two-stage thermoelectric cooler (C-TTEC) is designed and optimized for thermal performance enhancement. At the first stage, the cold side of N (N = 1, 2, 3, 4) pieces of thermoelectric modules (TEMs) are assembled around a cubic aluminum block with separate water-cooled heat sinks for heat dissipation. At the second stage, the hot side of another TEM is connected with the cubic aluminum block for heat dissipation. Compared with conventional square type two-stage TEC (S-TTEC) and pyramid type two-stage TEC (P-TTEC), the thermal performance, including cold side temperature and temperature difference between the hot and cold sides are greatly enhanced. The lowest cold side temperature is obtained through optimization of the structure of TTEC, voltage of TEMs at different stages and mode of heat dissipation. The thermal analysis shows that the ratio of the number of TEM in two adjacent stages is 3.2:1, rounded to 4:1, which is consistent with the experimental results. The experimental results show that the proposed C-TTEC can achieve temperature as low as −49.5 ℃, which is lower than that of P-TTEC without insulation (−34.3 ℃) and S-TTEC (−38.6 ℃). This work provides a good theoretical basis of the multi-stage thermoelectric cooler for thermal performance enhancement.

Features of Designing Computer Control Systems for Precision Thermoelectric Coolers

An effective electrical circuit and an operating algorithm have been developed, and a working sample of a thermoelectric precision thermostat has been designed with the possibility of autonomous operation, continuous monitoring and recording of the temperature log using a computer or smartphone. It is shown that the developed algorithm provides effective shockless control and an accuracy of maintaining the temperature of 0.03°C, with a power consumption of 3-7 W. A design and a specialized computer control system for a multistage cryogenic thermoelectric cooler have been developed.

Development of a solid-state multi-stage thermoelectric cooler

In this work, a unique thermoelectric solid-state multi-stage cooler for operating temperatures up to ~140 K was developed. The extrusion technology was applied to fabricate thermoelectric legs with sufficient mechanical properties for the device construction. A cooling prototype was designed and fabricated using a four-stage commercial module and a two-stage ultra-low temperature module. The ultra-low temperature module, operating in the temperature range of 180–140 K, was fabricated using Bi0·91Sb0.09 alloys as an n-type leg and an optimized composition of Bi1·6Sb0·4Te3 as a p-type leg. The four-stage commercial thermoelectric module based on n- and p-type Bi2Te3 based alloys was utilized for operation in the temperature range of 180–300 K. The solid-state cooler was tested at a hot temperature Th = 300 K in a vacuum. At the cold temperature of the fourth stage 180 K, the maximum temperature difference of the ultra-low temperature module achieves high values of maximum temperature difference ΔT = 45 K and maximum cooling capacity Qc = 85 mW. Furthermore, we demonstrated the applicability of the ultra-low cooler for refrigeration up to 150 K for a mid-infrared sensor based on a PbTe photodiode with a cut-off wavelength λc ≈ 4.2 μm and a detectivity D ≈ 1010 cm Hz1/2/W revealing the potential of the developed device for practical applications.

A review on thermoelectric cooling parameters and performance

Abstract This paper deals with a review of the main research aspects concerning the formulation of the parameters indicating the characteristics and performance of thermoelectric cooling devices, with particular reference to a number of recent publications. The specific aspects addressed include some practical considerations referring to the thermoelectric figure of merit, the characterization of the cooling capacity, and the assessment of the coefficient of performance ( COP ). The contribution of this paper starts by categorizing the topics addressed by recent review papers, showing that these reviews generally had a wide focus and provided little specific details on thermoelectric cooling parameters and performance. Then, the dimensionless thermoelectric figure of merit is addressed by focusing on its conventional and modified definitions and indicating the values obtained for different thermoelectric cooling materials. Furthermore, the expressions of the cooling capacity for single-stage and multi-stage thermoelectric coolers are reviewed. Concerning the COP , its dedicated expressions are constructed starting from the classical formulation and introducing additional factors or modifications in order to take into account the Thomson effect, the dependence on temperature of the thermoelectric materials, and the effects of the electrical contact resistance, thermal resistance, thermoelement length and current. Finally, on the basis of the indications taken from the literature, further considerations are included on the COP values found in thermoelectric cooling applications, as well as on how to obtain COP improvements.

A Comparison of Performance Characteristics of Multistage Thermoelectric Coolers Based on Different Ceramic Substrates

The influence of the thermal properties of the substrate on the performance of cascade thermoelectric coolers (TECs) is studied with an emphasis on a justified choice of substrate material. An analytical model is developed for predicting the thermal resistance of the substrate associated with three-dimensional heat transfer from a smaller cascade area into a larger cooling cascade. The model is used to define the maximum temperature difference for a line of standard multistage TECs based on various substrate materials with different thermal conductivities, including white 96% Al2O3 “Rubalit” ceramic, grey 99.8% Al2O3 “Policor” ceramic, and AlN and BeO ceramics. Two types of multistage TECs are considered, namely with series and series–parallel connection of TE pellets, having from two to five cascades with TE pellet length in the range from 0.3 mm to 2 mm. A comparative analysis of the obtained results is made, and recommendations are formulated concerning the selection of an appropriate substrate material providing the highest performance-to-cost ratio.

Parametric System Identification of Thermoelectric Cooler for Single Photon Avalanche Diode Application

The purpose of this study is to model the Thermoelectric Coolers (TEC) by means of computational intelligence system identification. Thermoelectric coolers are widely used in cooling, maintaining and stabilizing the temperature of the Single Photon Avalanche Diode (SPAD). SPAD is a temperature sensitive optoelectronic device, where even a slight variation in temperature can cause unstable performance in quantum efficiency, responsibility and dark counts. However, it is not a simple task to derive a mathematical model for TEC since it varies with the operating condition. In this study, Particle Swarm Optimization (PSO) was used to identify the mathematical model of the multistage TEC (1639733 from Element 14), which encapsulates dynamics of the SPAD, heat sink and components of the cooling heat exchanger. The model was validated by correlation tests, percentage accuracy and also by comparing its time and frequency responses against that of the TEC. It was found that the obtained model has a good representation of the actual system.

Exergy analysis of single-stage and multi stage thermoelectric cooler

Thermoelectric devices are solid-state devices. Semiconductor thermoelectric cooling, based on the Peltier effect, has interesting capabilities compared to conventional cooling systems. In this work second law analysis of thermoelectric coolers has been done with the help of exergy destruction. In the first part, performance of single-stage thermoelectric coolers and multi stage thermoelectric coolers has been compared for same number of thermoelectric elements i.e. 50. The performance parameters considered to compare their performance are rate of refrigeration, coefficient of performance, second law efficiency and exergy destruction. In second part, multi stage thermoelectric coolers have been analyzed for three different combinations of number of elements in two stages of thermoelectric coolers. The result of the analysis shows that the performance of a multi stage thermoelectric cooler which has total 50 elements gives best performance when it has 30 elements in hotter side and 20 elements in colder side out of the three cases considered. The comparison of single-stage thermoelectric cooler and multistage thermoelectric cooler shows that for same number of elements rate of refrigeration (ROR) of single-stage thermoelectric cooler is much higher than that of multi stage thermoelectric cooler. The COP remains same for both of them but the peak value of cop is obtained at much lower value of current supplied in multi stage thermoelectric cooler. Exergy destruction has constant values in single stage as well as multi stage thermoelectric cooler when the two stages have equal number of elements but it decreases with increase in x. The result of comparison of multistage thermoelectric cooler for three values of x i.e. 0.5, 1, 1.5 shows that the COP, ROR and second law efficiency improve and exergy destruction degrades with increase in x and the best performance has been obtained for x = 1.5 out of the three values considered. Copyright © 2013 John Wiley & Sons, Ltd.

Performance analysis of multi-stage thermoelectric coolers

Multi-stage thermoelectric coolers offer larger temperature differences between heat source and heat sink than single-stage thermoelectric coolers. In this paper, a pyramid-type multi-stage cooler is analyzed, focusing on the importance of maximum attainable target heat flux and overall coefficient of performance, COP. Having considered the COP and the thermal resistance of a heat sink as key parameters in the design of a multi-stage thermoelectric cooler, analytical formulas for COP and heat sink thermal resistance versus working electrical current are derived. For a fixed cooling target heat flux, the ratio of the heat sink thermal resistance to the respective single-stage value and the attainable COP in a cascaded cooler are determined as a function of the number of stages. Numerical simulations clearly indicate that the thermal resistance of the hot side heat sink is the controlling factor in determining the overall performance of a multi-stage thermoelectric cooler.

Materials based on bismuth and antimony chalcogenides for thermoelectric cooler stages

To enhance the efficiency of multistage thermoelectric coolers, extruded materials based on p- and n-type solid solutions of bismuth and antimony chalcogenides have been optimized for particular temperatures in the range 100–300 K. We have studied the effect of selenium doping on the thermoelectric efficiency of the p-type materials. We have fabricated pilot micromodules and compared calculated and experimentally determined characteristics (maximum temperature difference and thermoelectric figure of merit) of the modules in the range 100–300 K.

A method for calculating the transient time of a multi-stage thermoelectric cooler

The transient time τ of a cascade thermoelectric cooler is calculated. The method applied does not involve the solution of the heat equations with partial derivatives for semiconductor elements. The transient time τ of a two-stage thermopile was obtained in analytical form as a solution of the quadratic equation whose coefficients depend on semiconductor thermoelectric parameters, the specific heat of the thermopile materials, and the sizes of different parts of the cooler. For a thermopile with an arbitrary number of stages N, the calculation was reduced to the standard problem of finding the eigenvalues of two symmetrical matrices of order N. The calculated values of τ for specific two-stage thermopiles are in satisfactory agreement with the experimental data.

Multistage thermoelectric microcoolers

Multistage thermoelectric coolers have been used for a long time because they offer a larger temperature difference than single-stage thermoelectric coolers. Microelectromechanical systems technology leads to the possibility to fabricate multistage thermoelectric microcoolers in batches without much increase in complexity compared to single-stage cooler fabrication. In this paper, we design and analyze such multistage coolers, focusing on the optimization of the maximum temperature difference, which is of particular interest for multistage microcoolers. As an example, a two-stage thermoelectric microcooler is designed for the thermal management of a 10 mW mid-infrared laser. The heat leakage issue, the most important degradation mechanism for the performance of thermoelectric microcoolers, is discussed and possible solutions are also outlined.

Temperature–entropy diagrams for multi-stage thermoelectric coolers

In this work, we extend the temperature–entropy formulation to multi-stage thermoelectric coolers. With reference to commercially available thermoelectric materials, temperature–entropy diagrams are constructed to facilitate understanding the effects of electric current(s) and/or ratios of the number of thermocouples between stages on devices' performance. The temperature dependence of material properties is taken into consideration.

Optimum staging of multistage exo-reversible refrigeration systems

A general staging model is developed to optimize multistage exo-reversible refrigeration systems affected solely by internal irreversibilities. Under some reasonable assumption, the same high to low temperature ratio is found at each stage so as to maximize the coefficient of performance of a multistage combined refrigeration system, where each stage is subjected to an independent refrigeration subcycle. This model is then applied to the optimum staging of two configurations of multistage thermoelectric coolers, which are the ones with different and identical electrical current flowing through each stage, respectively. For both the two cases, the optimum stage temperatures are numerically proved to follow from the ideal staging well. Detailed optimum staging parameters of both types of thermoelectric coolers are calculated with commercially available thermoelectric (TE) materials. The temperature dependence of TE properties has been taken into account.

Supercooling of Peltier cooler using a current pulse

The operation of a Peltier cooler can be temporarily enhanced by utilizing the transient response of a current pulse. The performance of such a device, using (Bi,Sb)2Te3-based thermoelectric elements, was examined from −70 to 55 °C. We establish both theoretically and experimentally the essential parameters that describe the pulse cooling effect, such as the minimum temperature achieved, maximum temperature overshoot, time to reach minimum temperature, time while cooled, and time between pulses. Using simple theoretical and semiempirical relationships the dependence of these parameters on the current pulse amplitude, temperature, thermoelectric element length, thermoelectric figure of merit and thermal diffusivity is established. At large pulse amplitudes the amount of pulse supercooling is proportional to the maximum steady-state difference in temperature. This proportionality factor is about half that expected theoretically. This suggests that the thermoelectric figure of merit is the key materials parameter for pulse cooling. For this cooler, the practical optimum pulse amplitude was found to be about three times the optimum steady-state current. A pulse cooler was integrated into a small commercial thermoelectric three-stage cooler and it provided several degrees of additional cooling for a period long enough to operate a laser sensor. The improvement due to pulse cooling is about the equivalent of two additional stages in a multistage thermoelectric cooler.