Thermoelectric Cooler Research Articles

In-orbit validation of a ferrofluidic Thermal Switch in ISS microgravity

AbstractFerrofluids offer a wide range of applications by enabling wearless systems for future space missions. As part of the FARGO (Ferrofluid Application Research Goes Orbital) project, an active Thermal Switch using ferrofluid was developed and validated during a 26-day International Space Station (ISS) mission. This experiment was conducted as part of the Überflieger2 competition organized by the Space Agency within the German Aerospace Center (DLR). Thermal management of spacecraft (S/C) and satellites is a universal challenge. In the development of thermal management components, it is therefore essential to minimize or even eliminate stress/strain peaks and potential safety risks for S/C operation and payloads induced by thermal differences. The thermal management system shall be able to keep all components within their acceptable temperature ranges. This shall be achieved under all orbit conditions, for example, when solar irradiance heats one side of the S/C resulting in possibly unwanted temperature gradients toward the cold vacuum of space. An active Thermal Switch allows heat flows to be routed along different paths within the S/C depending on the prevailing conditions. Within project FARGO, an active Thermal Switch was tested during an ISS mission. Tests on the ground already verified a measurable difference in thermal conductivity depending on the state of the switch. Magnetically moving the ferrofluid allows the creation of a thermally isolating and conducting Thermal Switch state. The ferrofluid utilized for the FARGO experiment is EFH-1 with a thermal conductivity of $${0.19\,\mathrm{\text {W}\text {m}^{-1}\text {K}^{-1}}}$$ 0.19 Wm - 1 K - 1 . The Thermal Switch consists of two silver rods in line, acting as heat conductors, separated by an airgap. One side of the switch is heated, and the other one cooled by one thermoelectric cooler (TEC) each. The gap between the conductors can be bridged by ferrofluid moved via magnetic fields. As the EFH-1 has a higher thermal conductivity k than air, thermal conductive change is achieved by switching. The temperature difference between hot and cold side are measured in the ON state as well as the OFF state. From these measurements, the switching ratio as a performance characteristic is calculated. The switch was tested under various heat loads and switching times. Electropermanent magnets (EPMs) are magnets that can be magnetically switched on and off by a current pulse. Compared to conventional electromagnets, heat generation and power generation are significantly reduced. In addition, the switch remains reliably in the selected state, even if a failure of the control electronics occurs, making it bi-stable. Moreover, electric power is only required to switch the state of the EPM, but not to maintain it.

Comprehensive study of serpentine heat exchangers in thermoelectric coolers: experimental and numerical approaches

Comprehensive study of serpentine heat exchangers in thermoelectric coolers: experimental and numerical approaches

Compact Si-SiN photonic fiber optic gyroscope transceiver for large volume manufacturing

Miniaturized interferometric fiber optic gyroscopes (IFOGs) providing high-precision angular measurement are highly desired in various smart applications. In this work, we present a high-performance Si-SiN photonic FOG transceiver composed of an optical source, polarizer, splitter, and on-chip germanium (Ge) photodetector (PD). The transceiver is assembled in a standard butterfly package with a thermo-electric cooler (TEC). The optical loss (including two edge couplers, as well as one 3 dB splitter) and polarization extinction ratio (PER) are less than 7 dB and greater than 20 dB at room temperature, respectively. Built with the polarization maintaining (PM) fiber coil with 70 mm average diameter and 580 m length, the transceiver-based IFOG exhibits record-low bias stability of 0.022 deg/h at an integration time of 10 s, the angular random walk (ARW) of 0.0012 deg/h, and the bias instability of 0.003 deg/h, to the best of our knowledge. The preliminary reliability test agrees well with the practical requirements. Our work verifies that the on-chip Ge PD is eligible for high-performance FOG applications. Leveraged with the typical CMOS compatible 8-inch (200 mm diameter wafers) silicon photonics platform and decreased fiber splicing points, the presented transceiver provides a promising solution toward a low-loss and miniaturized FOG system with large volume manufacturing capability.

PbSe Thermoelectrics: Efficient Candidates for Power Generation and Cooling

AbstractThermoelectric materials enable efficient and clean conversion between heat and electricity, offering significant application prospects in waste heat recovery and solid‐state cooling. Lead selenide (PbSe) is a more abundant and cost‐effective alternative to PbTe with promising potential for mid‐temperature applications. However, things have changed very recently with the discovery of the traditional power generator PbSe being rather competitive as a thermoelectric cooler, opening new avenues for investigating this compound. This review aims to comb how the research achievements and promising performance of PbSe have shifted from medium to near‐room temperatures, by comprehensively discussing various strategies to enhance the thermoelectric efficiency at different temperature ranges. Subsequently, it is reviewed how these advances in materials have triggered deep investigations on constructing high‐efficiency power generation and cooling devices based on PbSe. Finally, a personal summary and outlook are presented on how to fully exploit the high‐ranged thermoelectric performance of PbSe materials and manufacture high‐efficiency power generators and coolers, thus promoting practical applications in the future.

EXTH-74. COOLING GLIOBLASTOMA WITH A NEURAL IMPLANT

Abstract Survival rates for glioblastoma (GBM) patients are low due to the difficulty in eradicating all tumor cells, leading to frequent recurrence. This recurrence is frequently within 2-cm from the original site. Studies indicate that supra-total resection improves survival, and non-destructive local therapies show promise in preventing GBM recurrence. Our research demonstrates that non-freezing, ‘cytostatic’ hypothermia is effective against GBM in rats and can be scaled to pig models. This method, unlike ablative cryogenic hypothermia, safely inhibits GBM growth without damaging healthy tissue. Using in vitro culture models and in vivo rat models via a Peltier device, we tested cytostatic hypothermia. This was followed by finite-element modeling (FEM) to simulate bioheat transfer in human and pig brains. The system consists of a neural implant with a multiprobe array, a Peltier chip, a water block, and an artificial internal circulation system with a piezoelectric pump. In vitro tests identified a cytostatic window of 20–25°C. Miniature Peltier devices were fabricated to achieve this in rats to inhibit GBM growth and extend survival. Rats whose tumors received cytostatic levels of hypothermia survived their full study period. FEM simulations confirmed that multiprobe arrays could cool brain tissue to 25°C without significantly raising skin temperature. Portable systems were successfully fabricated and tested in pigs, achieving safe target temperatures with minimal EEG and OCTA changes. Our findings suggest that cytostatic hypothermia can be scaled to larger animals and made implantable and portable, offering a promising non-destructive approach to halting GBM growth and prolonging survival, moving closer to becoming a viable treatment option for patients with GBM.

Interplay of c- and a-domains on the anomalous electrocaloric effect in BaTiO3 (001) single crystals

Electrocaloric effects of adiabatic temperature change via the application of external electric fields are explored for energy-efficient solid-state refrigeration. These effects are typically estimated from the thermodynamic analyses of polarization and field in electrocaloric materials, which implies that higher field application gives larger temperature changes. However, this may not be always true. Here, using both indirect and direct methods, we report an anomalous effect where larger thermal changes occur by applications of lower fields in a multi-domain BaTiO3 (001) single crystal. A large temperature change of 1.9 K under a low field change of 8 kV/cm at 404 K is observed in a multi-domain BaTiO3 (001) single crystal in comparison to that of 1.4 K at a high field change of 30 kV/cm. We attribute this counterintuitive effect to the interplay of the c- and a-domains in the BaTiO3 (001) single crystal under the influence of temperature and field changes. This work provides a fundamental understanding of the complex role of domains in governing the electrocaloric response of ferroelectric materials which is often overlooked but critical for their practical applications.

Flexible Bridged Thermoelectric Device with an Optimized Heatsink for Personal Thermal Management.

A wearable thermoelectric cooler (TEC) for personal thermal management exhibits significant growth in numerous applications in personal thermal comfort and saving the energy consumed by space cooling. Most TECs provide a large cooling performance with the assistance of rigid heatsinks and electrodes, limiting wearability and practical implementation. Here, we design and propose a flexible bridged personal TEC with a high thermal management heatsink and spray-printed liquid metal electrodes. The system combines a bendable heatsink, a thermally insulative TE layer, and a bottom thermally conductive layer. Especially, the flexible heatsink composed of metal foam, phase change material, and fin structure greatly enhances the thermal conduction, storage, and diffusion capacities. Our TEC exhibits the desired comfortability and obtains an ideal temperature drop of 3 °C on human skin. Also, it could work as a self-generator providing 45 mV with a ΔT of 5 °C, which improves the generation efficiency by more than 3 times due to the stable temperature difference between the two sides. This work provides an effective way to develop wearable TEC devices and paves the way for achieving practical, personalized cooling applications.

Enhancing the cooling performance of thermocouples: a power-constrained topology optimization procedure

Heat pumping through thermoelectric devices has many advantages over traditional cooling. However, their current efficiency is a limiting factor in their implementation. In this paper, we approach the non-convex topology optimization of thermoelectrical elements for cooling applications through the method of moving asymptotes (MMA) to improve their cooling capabilities per watt usage. The optimization problem is defined for a given power budget, aiming for the minimum temperature with a known heat pumping need. The introduction of power as a constraint justifies the introduction of the voltage gradient across the thermocouple as a design variable to maintain the thermoelectrical device in its optimum power-to-heat extraction ratio. To better understand the convergence of this non-convex problem, we present a two-variable analytical thermoelectric optimization model. This example provides information on how to select the penalty parameters used to scale the three material coefficients involved in the problem to obtain lower objective values and better convergence using MMA. The analytical model shows the non-convexity of the problem and provides the recommendation to use penalization coefficients of the form pk=pσ>pα=1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p_k=p_{\\sigma }>p_{\\alpha }=1$$\\end{document} for the thermal conductivity, electrical conductivity, and Seebeck coefficients. We tested these penalization coefficients through optimizations of a model based on the 1MC10-031 commercial thermoelectric-cooler (TEC) using the finite element method (FEM). These penalization coefficients provided local minima without the need for volume constraints. With this procedure, we found designs that provided temperatures close to 10 degrees lower using 60% less semiconductor material volume compared to the initial design.

Demonstration of efficient Thomson cooler by electronic phase transition.

In the 1850s, Lord Kelvin predicted the existence of a thermoelectric cooling effect inside a whole material (the Thomson effect) according to thermodynamics1, in addition to the Peltier effect that enables cooling at the junction between dissimilar materials. However, the Thomson effect is usually negligible (ΔT/T < 2%) in conventional thermoelectric materials because the entropy change in charge carriers is fairly small2, leading to the guiding principles for advancing thermoelectric cooling to be based on the framework of the Peltier effect and that the figure of merit ZT should be maximized to optimize performance. Here, we demonstrate a Thomson-effect-enhanced thermoelectric cooler using a large Thomson coefficient (τ) induced by the direct manipulation of charge entropy through an electronic phase transition in YbInCu4. The devices achieve a steady temperature span (ΔT) of >5 K from T = 38 K. Our findings suggest not only another approach to advance thermoelectric coolers in addition to improving ZT but also technologically opens opportunities for solid-state cryogenic cooling applications.

Early Fault Detection and Operator-Based MIMO Fault-Tolerant Temperature Control of Microreactor

A microreactor is a chemical reaction device that mixes liquids in a very narrow channel and continuously generates reactions. They are attracting attention as next-generation chemical reaction devices because of their ability to achieve small-scale and highly efficient reactions compared to the conventional badge method. However, the challenge is to design a control system that is tolerant of faults in some of the enormous number of sensors in order to achieve parallel production by numbering up. In a previous study, a simultaneous control system for two different temperatures was proposed in an experimental system that imitated the microreactor cooled by Peltier devices. In addition, a fault-tolerant control system for one area has also been proposed. However, the fault-tolerant control system could not be applied to the control system of two temperatures in the previous study. In this paper, we extend it to a two-input, two-output fault-tolerant control system. We also use a fault detection system that combines ChangeFinder, a time-series data analysis method, and One-Class SVM, an unsupervised learning method. Finally, the effectiveness of the proposed method is confirmed by experiments.

Research and thermal comfort analysis of the air conditioning system of the Ferris wheel car based on thermoelectric cooling

To solve the problem of thermal discomfort caused by the lack of cooling facilities on the Ferris wheel and to investigate the effect of the coupling effect of thermoelectric modules on the thermoelectric cooling (TEC) system, this paper proposes a two-module thermoelectric cooling and air-conditioning system that can be applied to the Ferris wheel. Firstly, the experimental platform was established to test the performance parameters of the TEC system and reveal the influence of the thermoelectric module (TEM) coupling effect on the system performance. Then, the thermal environment inside the Ferris wheel was simulated using the CFD method and human thermal comfort was evaluated. The results show that when the voltage of TEM1 and TEM2 is 10 V and 6 V respectively, the thermoelectric cooling and air-conditioning system has the best working performance, and the coefficient of performance (COP) is 0.43. And the human thermal comfort deviation AEQT is 0.29, which is in a comfortable state under the action of the air-conditioning system.

A point of view of the elastocaloric effect associated with 7M and 5M modulated martensite in Ni–Mn–Ga alloys

Solid-state refrigeration has emerged as the most promising alternative to conventional refrigeration technology. However, for this technology to be applicable, the caloric effects produced in the alloys must be highly reversible. In this context, we compare the elastocaloric effect of two Ni–Mn–Ga alloys with different types of modulated martensite. The elastocaloric effect, quantified as the isothermal entropy change (ΔSela), was investigated in Ni50Mn28Ga22 and Ni50Mn30Ga20 alloys with 5M and 7M modulated martensite, respectively. Maximum ΔSela values obtained were 1.91 J kg−1 K−1 during cooling and 1.83 J kg−1 K−1 during heating in martensite 5M and 0.19 J kg−1 K−1 during cooling and 0.26 J kg−1 K−1 during heating in martensite 7M, for a constant applied stress of 10 MPa. However, although the 7M modulated martensite exhibited a lower ΔSela, its reversibility was higher. Therefore, our results could be useful for selecting a good material to be used in solid-state refrigeration.

The DFT prediction of comprehensive properties of antiperovskites Mg6CX4 (X = S, Se, Te) and effects of defects and surface adsorption

It is important to search potential materials to meet ever-increasing demand in various fields. In order to understand the new hexagonal antiperovskites material Mg6CX4 (X=S, Se, Te), their mechanical, electronic and optical properties were studied based on density functional theory (DFT). The structural stability has been confirmed by the elastic constant criteria, formation energy, phonon dispersion spectra and ab-initio molecular dynamics (AIMD) simulation performed at 300 K. Besides, the Poisson's ratios over 0.26 demonstrate the ductility of the studied materials. They all have direct electronic band structures with bandgaps of 0.977 eV for Mg6CS4, 0.809 eV for Mg6CSe4 and 1.274 eV for Mg6CTe4, respectively. The calculated melting temperatures are all around 1000 K, which indicates the potential for high-temperature application. Therefore, Mg6CTe4 fits most for absorber in solar cells due to its proper bandgap and dispersive band edge. The antiperovskites exhibit high and broad light absorption in visible and near ultraviolet region with absorption coefficient greater than 104 cm−1, which inidcates a broad applicable prospect in optoelectronic field. Mg6CTe4 is also a candidate for efficient solid-state refrigeration due to its lowest thermal conductivity as 0.0046 W/(K•m). The defect analysis suggests that oxygen defects are the most favorable and have complex effects on bandgaps. The high bandgap sensitivity to surface adsorbates implies potential application in gas detector.

Machine-Learning-Driven Design of High-Elastocaloric NiTi-Based Shape Memory Alloys

In recent years, the detrimental impact of traditional gas–liquid refrigerants on the environment has prompted a shift towards sustainable solid-state refrigeration technology. The elastocaloric effect, particularly in NiTi-based shape memory alloys (SMAs), presents a promising alternative due to its high coefficient of performance. However, conventional methods for alloy development are inefficient, often failing to meet the stringent requirements for practical applications. This study employed machine learning (ML) to accelerate the design of NiTi-based SMAs with an enhanced elastocaloric effect. Through active learning across four iterations, we identified nine novel NiTi-based SMAs exhibiting phase-transformation-induced entropy changes (ΔS) greater than 90 J/kg·K−1, surpassing most existing alloys. Our ML model demonstrates robust interpretability, revealing key relationships between material features and performance. This work not only establishes a more efficient pathway for alloy discovery but also aims to contribute significantly to the advancement of sustainable refrigeration technologies.

Kinetic origin of hysteresis and the strongly enhanced reversible barocaloric effect by regulating the atomic coordination environment

Hysteresis is an inherent property of first-order transition materials that poses challenges for solid-state refrigeration applications. Extensive research has been conducted, but the intrinsic origins of hysteresis remain poorly understood. Here, we report a study of the kinetic origin of hysteresis and the enhanced barocaloric effect (BCE) in MnCoGe-based alloys with ~2% nonmagnetic In atoms. First-principles calculations demonstrate that substituting In atoms at Ge sites rather than Co sites results in a lower energy barrier, indicating a narrower hysteresis for the former. Combining neutron powder diffraction (NPD) with magnetic and calorimetric measurements completely verified the theoretical prediction. Electron local function (ELF) calculations further reveal the atomic coordination origin of regulated hysteresis due to weaker Co–Ge bonds when In atoms replace Ge, which is opposite to Co sites. Moreover, we experimentally investigate the BCE and find that although MnCo(Ge0.98In0.02) has a lower barocaloric entropy change ΔSP than does Mn(Co0.98In0.02)Ge, the reversible ΔSrev of the former is advantageous owing to a smaller hysteresis. The maximum ΔSrev of MnCo(Ge0.98In0.02) is 1.7 times greater than that of Mn(Co0.98In0.02)Ge. These results reveal the atomic-scale mechanism regulating hysteresis and provide insights into tailoring the functional properties of novel caloric refrigeration materials.

Design of a thermoelectric cooler to control the temperature of telecom outdoor cabinet

This paper discusses the design of a thermoelectric cooler (TEC) system for controlling the temperature of telecom outdoor cabins. Traditional cooling methods, such as refrigerants, have potential negative impacts on the environment, making thermoelectric cooling systems a promising alternative due to their efficiency, environmental friendliness, and versatility. The paper reviews the current state of the art in designing thermoelectric cooler systems for absorbing heat generated from telecom electronic devices. The literature review highlights studies that have evaluated the cooling performance, energy efficiency, and cost-effectiveness of thermoelectric cooling systems for telecom electronic devices. The objective of this project is to design a TEC system that can absorb the heat generated from telecommunication cabinets. The design is generated analytically using the TE ideal equation with a heat sink or heat exchanger system. The design aims to investigate the optimum current and geometric ratio that can improve the cooling capacity of the TEC system. The paper also presents a modeling approach for thermoelectric coolers with two heat sinks. The study concludes that thermoelectric cooling systems have the potential to provide efficient and environmentally friendly cooling solutions for telecom electronic devices, and future studies should continue to investigate and optimize the design of thermoelectric cooling systems for various types of telecom electronic devices.

A non-contact thermocapillary driving system at the gas-liquid interface

Non-contact driving technology is widely utilized in various fields due to its advantages of being non-contact, wear-free, and low noise. Thermocapillary driving is an effective approach for non-contact driving at gas-liquid interfaces. When a temperature gradient exists at the gas-liquid interface, it generates a surface tension gradient, which drives the movement of micro-objects at the interface. This research proposes a system that utilizes an array of thermoelectric coolers (TECs) as a heat source, which changes the local temperature at the gas-liquid interface and generates surface tension gradients for driving the movement of interface objects. Experimental results demonstrate that foam particles with a diameter of 0.5 mm can achieve a maximum moving speed of 2.1 mm/s. Furthermore, the system can control multiple micro-objects at the gas-liquid interface for self-assembly. We have also developed a miniature biomimetic water strider robot, this system can drive the robot to perform linear and turning movements at the gas-liquid interface. This system provides a novel approach for non-contact driving of gas-liquid interfaces.

Embedded IoT Design for Bioreactor Sensor Integration

This paper proposes an embedded Internet of Things (IoT) system for bioreactor sensor integration, aimed at optimizing temperature and turbidity control during cell cultivation. Utilizing an ESP32 development board, the system makes advances on previous iterations by incorporating superior analog-to-digital conversion capabilities, dual-core processing, and integrated Wi-Fi and Bluetooth connectivity. The key components include a DS18B20 digital temperature sensor, a TS-300B turbidity sensor, and a Peltier module for temperature regulation. Through real-time monitoring and data transmission to cloud platforms, the system facilitates advanced process control and optimization. The experimental results on yeast cultures demonstrate the system’s effectiveness at maintaining optimal growth, highlighting its potential to enhance bioprocessing techniques. The proposed solution underscores the practical applications of the IoT in bioreactor environments, offering insights into the improved efficiency and reliability of culture cultivation processes.

Repeated γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma $$\\end{document} irradiation and thermal annealing via built-in thermo-electric coolers of Si avalanche photodiodes

When operating in space, on-board Silicon Geiger-Mode Avalanche Photodiodes (GM-APDs) are exposed to radiation damage that result in an increase in dark count rates. Thermal annealing has been found to mitigate the damage, although prior studies have largely focused on annealing following a single session of proton irradiation. This work reports that thermal annealing can be performed simply with the built-in thermo-electric coolers of the GM-APDs. Annealing was also done in 10 min intervals for a clearer view of the recovery curve. Mitigation of damage from repeated γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma $$\\end{document} radiation was observed from the: (1) halving of the increase in dark count rates on average and (2) outperformance of room temperature annealing (25∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$25\\,^{\\circ }$$\\end{document}C) by 33%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document}. Additionally, we show that heavy doses of γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma $$\\end{document} radiation (21 krad) have a probability of causing Random Telegraph Signals in GM-APDs that can be suppressed by lowering the operating temperature.

Preliminary study of the thermoelectric cooler and heat pipe application for the cooling system in cabin pickup car

Abstract Car cooling systems are essential equipment to make passengers comfortable, but their energy consumption is very high. Thermoelectric technology has been widely applied as a cooler in many applications, but its use as a car cooler has not been widely used. This research aims to conduct a preliminary study using thermoelectric coolers (TEC) as alternative coolers in pickup cars and to investigate the effect of thermoelectric module and heat exchanger configurations on cooling systems performance. A-TEC cooling system usually uses conventional heat sinks on the cold side and hot side of the TEC. In this study, heat pipes are used as heat exchangers on the hot side of TEC to improve its performance. The cooling system consists of 2 units installed at the rear of the pickup car cabin. Tests were varied using 2 TEC modules arranged in series and 4 TECs arranged in parallel thermal and electrical series. The results showed that using two cooling system units consisting of four TEC modules equipped with heat pipes was able to cool the temperature of the pickup car cabin at 27.4 °C and obtained the highest COP value of 1.16. It shows heat pipes can enhance TEC cooling system performance, producing lower cabin temperatures than conventional heat sinks.