Thermoelectric Cooling Devices Research Articles

Assessment and validation of a numerical model for phase change materials heatsink on thermoelectric devices

The use of phase change materials (PCM) in heatsink designs are gaining attention due to its many favorable properties. Some PCM heatsinks designs have been suggested for use with thermoelectric cooling devices (TECs), however, the heatsink designs are often arbitrary where PCM is just added to voids within the heatsink to improve the thermal properties. There is a need to systematically understand the effects of PCM on TEC performance. While a numerical model is key to such systematic study and optimization, the application involves multiple physical phenomena and the resulting model can be prohibitively expensive to run. In this contribution, a numercical model using computational fluid dynamics (CFD) is built to predict the performance of PCM heatsink for use with TECs as cooling wearable. Experiments are calibrated and carried out to prescribe the boundary conditions and ensure that the multiphysics phenomena are accurately captured. The numerical methodology described here can be used for design optimizations of PCM heatsinks to be used in conjunction with TECs. Our numerical model shows that for maximum TEC efficiency, the PCM should be kept at a liquid fraction of less than 40%.

Feasibility evaluation of a thermoelectrically cooled photovoltaic module at different arrangements and working conditions: A numerical study

The performance of photovoltaic (PV) modules decreases due to heating in real working conditions. To test the feasibility of utilizing thermoelectric cooling (TEC) devices for active thermal management of PV modules, different hybrid PV-TEC systems are modeled. A numerical model is developed by finite volume method with an iterative solution procedure proposed to handle the resulting non-linear system of equations. Two different thermoelectric modules are incorporated in various numbers and spacings. Results show that if an optimum electrical current is supplied to the TEC devices, a marginal positive power gain can be obtained in most cases compared to an uncooled PV. However, the value of the optimum current is a function of TEC arrangement and also ambient conditions. The power gain of 1.17 W is observed for an insolation of 1000 W/m2 with 45 thermoelectric modules at 144 mm spacing. In general, increasing insolation and decreasing wind speed result in higher power gains in the hybrid system. The daily performance of the hybrid system with optimum electrical input improves 0.25 % and 0.1 % for a typical summer and winter day respectively, which is found to be inferior to passive cooling with fins for all investigated arrangements.

Thermoelectric Cooler Modeling and Optimization via Surrogate Modeling Using Implicit Physics-Constrained Neural Networks

Thermoelectric cooler (TEC) is a promising active cooling device to remove the localized hot spots precisely in VLSI chips. In this paper, we use a novel implicit physics-constrained neural networks (called IPCNN) to build a surrogate model for the single TEC device with the reduction from 3-D to 1-D. First, the surrogate model represented by the deep neural networks (DNN) allows parameterization of key design and running parameters, such as current density, length, and thermal boundary conditions of the TEC. Second, the proposed method tries to partition the physics laws into two different groups, which then are enforced by supervised learning and physics-informed neural networks (PINN) framework sequentially. Such implicit PCNN scheme can lead to much faster training speed and better convergent accuracy for the unsupervised training. The existing plain PINN enforces all the physics laws via the loss functions and the network tends to have very slow training speed and a large convergent error for large problems. An extreme learning machine (ELM) is used for the networks in the first stage. Compared with fully-connected network (FCN) trained by the traditional back-propagation algorithm, ELM can be easily trained and converges much faster. Furthermore, by leveraging the differential nature of the DNN model, we can directly estimate the derivative of the cooling heat flux with respect to current density instead of using a finite difference approximation. The calculated derivatives are used to find the optimal current density to achieve maximum cooling heat flux via Newton’s method. Last but not least, we propose a novel hybrid finite element neural network (FENN) method to perform thermal analysis of the VLSI chip system with the TEC device. The DNN model is embedded into COMSOL through the heat flux boundary conditions. Experimental results show that the ML-based method can achieve about 8.5× speedup with good accuracy than the COMSOL-based finite element method. Furthermore, the proposed IPCNN is more stable and accurate than the existing PINN. The proposed FENN can have a 5.1× speedup and 5.4× memory reduction over the traditional numerical method.

Current Control System for the Peltier Element in a Thermoelectric Cooling Device for Cooling the Human Head

. Thermoelectric semiconductor devices have been widely introduced in various sectors of the national economy. Methods of local thermal exposure are widely used in medical practice in the treatment and prevention of various diseases, such as mechanical injuries and diseases of joints and muscles, pain in the gastrointestinal tract, cholelithiasis and kidney stone disease, neuroses, arthrosis and arthritis, pharyngitis, tonsillitis, chronic fatigue, etc. At the same time, the thermal effect has a significant impact on the energy balance of the body. Under the influence of heat, blood and lymphatic vessels expand, improving blood circulation in many internal organs. The presence of such a device in medicine requires the creation of thermostats capable of influencing a local biophysical object using the Peltier element. This article discusses the development of a mathematical model for human head cooling devices using Peltier elements

Progress and Challenges for Thermoelectric Cooling: From Materials and Devices to Manifold Applications

Due to the unique advantages of precise temperature control, fast response, noiselessness, miniaturization, and eco-friendliness, thermoelectric cooling (TEC) technology has been recognized as an optimal solution to mitigate the global warming and energy crisis issues, as well as being an effective alternative for thermal management. In this review, we started with the discussion of the current TEC materials and devices, and then provided an extensive summary of the manifold applications of TEC technology including electronic thermal management, electric vehicles, zero energy buildings, medical treatments, and civil applications, etc. Finally, challenging aspects of TEC materials and devices, as well as the possible research directions for future applications in various fields for TEC technology, were proposed, providing important prospect and significant guidance for TEC community.

Electrothermal Simulation and Optimal Design of Thermoelectric Cooler Using Analytical Approach

In this article, electrothermal modeling and simulation of thermoelectric cooling (TEC) in the package design of VLSI systems are performed by solving coupled heat conduction and current continuity equations. We propose a new analytical solution to the coupled partial differential equations (PDEs) which describe temperature and voltage with the reduction from 3-D to 1-D. In addition to this, we derive new analytic expressions for two key performance metrics for TEC devices: 1) the maximum temperature difference and 2) the maximum heat-flux pumping capability, which can be guided for the optimal design of thermoelectric cooler to achieve the maximum cooling performance. Furthermore, for the first time, we observe that when the dimensionless figure of merit <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ZT_{0}$ </tex-math></inline-formula> value is larger than 1, there is no maximum heat-flux value, which means the heat dissipation due to the Peltier and Fourier transfer effects is larger than the heat generation caused by the Joule heating effect, which can lead to more efficient TEC cooling design. The accuracy of the proposed 1-D formulas is verified by a 3-D finite element method using COMSOL software. The compact model delivers many orders of magnitude speedup and memory saving compared to COMSOL with marginal accuracy loss. Compared with the conventional simplified 1-D energy equilibrium model, the proposed analytical coupled multiphysics model is more robust and accurate.

Numerical and Experimental Investigation on Symmetrical Cross Jet of Localized Air Conditioning System with Thermoelectric Cooling Devices in Commercial Vehicles

The localized air conditioning (LAC) system focuses on the micro environment around the human body, avoiding the energy waste of cooling the entire compartment. The application of small and flexible thermoelectric cooling devices (TEDs) provides more possibilities for automotive LAC, but also increase the collision and convergence of airflow at the same time. Therefore, the impact of symmetrical cross jet collision on the thermal environment in the cab has been analyzed through numerical simulation and experimental methods. The results show that the velocity and temperature of the dual jets in the merging zone have better uniformity. The human body also has better comfort under the environment constructed by the jets in this special state. The optimized jet collision angle is given to match the distance between the different air outlets and the human body in the thermal environment constructed by the localized air conditioner to achieve the best cooling effect. Real vehicle experiments and subjective evaluation of human comfort have been done to verify the cooling effect of the localized air conditioning system.

Study on Performance of the Thermoelectric Cooling Device with Novel Subchannel Finned Heat Sink

The thermoelectric refrigeration system is an application of the Peltier effect, and good refrigeration performance is dependent on effective heat dissipation performance. To enhance the cooling performance of the thermoelectric system, this paper designs a new type of finned heat sink, which does not change the overall size of the thermoelectric system. The performance of the refrigeration system under the new fin is tested by experiments under various conditions. During the experiment, the cooling wind speed, the temperature of the hot and cold side of the TEC, the power consumption of the fan, and other parameters were directly recorded through the measuring instrument. The results show that the use of new finned heat sinks can improve the COP of the thermoelectric refrigeration system. Within the scope of the study, the thermal resistance of the new fins can be reduced by 42.6%, and the system COP value can be increased by 22.8%. In addition, increasing the cooling wind speed can further reduce the cold side temperature. Within the research range, the lowest temperature can reach −8.25 °C, but the power consumed by the fan is 166% of that of the conventional fin heat sink refrigeration device.

Performance evaluation of PV-TEC coupling device for power production with improved hybrid nanocarbon based thermal material interface

The waste heat harnessing from photovoltaic module (PV) with the thermoelectric device (TE) is considered as an ideal solution for effective thermal management of PV technologies. However, idealized operating conditions for lossless device coupling and reduction in thermal contact resistance need to be investigated further to expedite PV-TE device efficiency. Our simple approach to tandemly attach a low-cost thermoelectric cooling device (TEC) to PV module has improved its power output and electrical efficiency by 1.02% and 1.1% respectively (No. of TEC device-1, 720 W/m2 and 20 °C of water-cooling). Herein, we explored the TEC device for power production as a cost-effective alternative to the traditional thermoelectric (TEG) devices. To facilitates the facile heat transport among the PV-TEC interface, the thermal interface material (TIM) has been applied on TEC devices. The hybridized paste of nanocarbon and thermal grease (NC-TG) was used as a TIM material, morphologically evident the linear alignment between NC in TG matrix has ameliorated the uniform heat conduction. It was observed that the application of hybrid Carbon TIM materials enhances the power generation by 10.65% compared to PV-TG-TEC. The physicochemical analysis and evaluation results indicated that the low-cost synthesized hybrid carbon-based TIM material is efficient in the reduction of thermal contact resistance. Concomitantly, the high heat absorption capacity of nanocarbon accelerated the TEC performance by creating a sufficient temperature gradient across TEC ends. The present work proposed a simple and low-cost pathway for the improvement of TEC performance using hybrid carbon-based TIM material.

Design and Optimization of Flexible Thermoelectric Coolers for Wearable Applications

Personalized cooling can provide comfort on the go and ultimately consume a fraction of the energy consumed by traditional space cooling techniques. Thermoelectric cooling (TEC) has emerged as a promising technology that can help us achieve personalized thermoregulation, but there is a lack of realization and application of flexible thermoelectric cooling modules for wearable applications. To promote the understanding and development of cooling devices working on thermoelectric principles, this paper discusses the methodology used for designing and characterizing wearable thermoelectric cooling modules for human body thermoregulation. A methodology to design a Flexible TEC device capable of achieving up to a temperature drop of 3 °C from high ambient temperature of 35 °C with low current consumption of 0.2–0.4 A and low heat transfer coefficient of 20 W m−2K−1 has been discussed. The module uses low fill factor (<10%) and high aspect ratio (>2) of legs to work in a highly resistive environment without needing external heat sinks for heat dissipation, capable of removing up to 0.08 W cm−2 of heat on cold side and providing more than 0.12 W cm−2 on the hot side.

Pulsed current effect on the performance of conical inhomogeneous thermoelectrics

A study of an inhomogeneous thermoelectric cooler (TEC) with conical thermoelectric elements (TEs) and temperature-dependent materials was conducted by the authors previously to obtain the TE temperature distribution profiles. As an accompanying investigation for the purpose of completeness, the overall system performance (the coefficient of performance) of a TEC device, in terms of the semiconductor geometric shape and its inhomogeneous material properties for two pulsed current profiles are explored in this study. Results concluded that a cost-effective TEC should consist of several features: the TE material with a large Seebeck coefficient offer favorable Peltier cooling power, a TE with a smaller cold end cross-section creates a lower transient temperature at the cold junction, and TEs with low material thermal conductivity minimize heat conduction to the cold junction. A customized selection of these design features, with a balance of the Peltier power, heat conduction, and distributed Joule heat within the TECs, produces an optimal thermoelectric cooling system.

Preliminary investigation on ultra-precision diamond turning of titanium alloys using thermoelectric cooler fixture

The low thermal conductivity of titanium alloys causes an accumulation of high cutting heat at the tool/workpiece interface and thus deteriorates surface integrity of the machined surface in ultra-precision machining (UPM). In response of this underlying source causing the poor machinability of the materials in UPM, in this study, a novel fixture composed of thermoelectric cooler (TEC) is firstly developed and applied into single point diamond turning (SPDT) of titanium alloys, aiming to dissipate the cutting heat in the machining process. The TEC contacted with workpiece during the whole turning process and caused a dissipation of cutting heat from the workpiece. By using the fixture with TEC device, the cutting force variation and surface roughness involved in SPDT were reduced. This study presents the preliminary results of application of TEC fixture on UPM of titanium alloys and shows the feasibility of the use of TEC device in UPM area, suggesting a new approach to resolve the problematic high cutting heat of titanium alloys in UPM.

Investigation Results and Analysis of Solar Cells Performance Enhancement by Cooling using Thermoelectric Cooling (TEC)

Solar energy received special attention and extensive studies were conducted to increase the efficiency of solar collectors and solar cells. One of the major problems of the operation of solar cells is the temperature rising which causes a reduction in the energy yield. The main objective of this work is to experimentally investigate the cooling effect of thermoelectric cooling devices (TEC) on solar cell performance. To overcome the rising temperature effect, the cooling by using the Peltier device is proposed and investigated. In this approach, the TEC cooling module is attached to the backside of the photovoltaic cell. It is assumed that the required power to run the TEC module is provided by the photovoltaic cell itself when the additional power obtained by the cooling is more than the needed power to operates the TEC device. The results show that the cooling of the tested PV cells/modules samples by using the Peltier TEC device was slightly enhanced the PV cells' performance. In our case of study for a 2Wp solar cell sample, the maximum temperature difference obtained due to Peltier cooling is about 5.3C° which produced an enhancement for the produced power and the open-circuit voltage by 7.02% and 2.64% respectively. However, the needed power to feed the Peltier element is significantly higher than the recovered power due to the Peltier cooling. The same trend was investigated for the tested samples of PV modules. So, the proposed combination of PV and Peltier cooling system was investigated to be economically not feasible regardless of the cost evaluation. Finally, the spatial effect and the proposed system can be improved significantly by altering and improving the performance of the Peltier element and the thermal characteristics of the solar cells/modules encapsulation material.

Effect of Thermoelectric Leg Thickness in a Planar Thin Film TEC Device on Different Substrates

Recently, mobile application processors (APs) have suffered from thermal issues such as local hot spot generation. Several approaches for chip cooling, such as dynamic thermal management, and heat pipe cooling, have been attempted so far, but, these solutions cannot completely eliminate increasing thermal issues. Therefore, in this study, we fabricated a planar type of thin film thermoelectric cooler (TEC) as an active cooling device for a mobile AP chip. We studied the effect of thickness on a planar thin film TEC device related to Joule heating and demonstrated the Peltier cooling effect on polyimide (PI) and Si substrates. The optimal thicknesses of n-type Bi2Te3 and p-type Sb2Te3 films were evaluated by ANSYS® simulation, and are 5.05 μm and 5.45 μm, respectively. It was shown that heat moves to the TE leg on the PI substrate, while the Si substrate serves as a heat sink according to the IR thermography analysis. The optimal thickness of the TE showed a temperature difference between the cold junction and hot junction up to 1.3 °C.

Junction temperature control of UV-C LEDs based on a thermoelectric cooler device

Junction temperature (TJ) control is mandatory to improve the optical efficiency, lifetime and the wavelength accuracy of the UV-C LED light sources. Thermoelectric cooler devices allow a critical control of the junction temperature, based on direct measurement of the solder point temperature. A PID control technique was implemented to control the voltage in the TEC devices and therefore the desired range of junction temperatures. The PID parameters are obtained with computational simulations based on physical models and experimental recordings of the solder temperature dynamics. Optical performance improves is demonstrated and the better lifetime could be achieved.

Cooling load and noise characterization modeling for photovoltaic driven building integrated thermoelectric cooling devices

Photovoltaic driven thermoelectric cooling devices are investigated for installation in a modular outdoor test-room. Because of Peltier effect in a thermoelectric cooling (TEC), heating and cooling is achieved by applying a voltage difference across the thermoelectric module. Theoretical design modeling of cooling load and noise characterization of building integrated Thermoelectric (TEC) Devices is analyzed. System design of photovoltaic driven TEC devices is investigated with varying fresh outdoor ventilation rates. Building integrated design of TEC devices inside ceiling suspended duct along with TEC devices mounted on wall driven by rooftop and active façade photovoltaic devices is considered in the analysis. In this way, two-stage dehumidification is achieved by two different sets of TEC devices. The investigation is conducted for effect of voltage, air flow rate and height of fin heat transfer surface. Expressions along with results for noise characterization in photovoltaic driven building integrated TEC devices are also provided.

Metaheuristic Techniques in Enhancing the Efficiency and Performance of Thermo-Electric Cooling Devices

The objective of this paper is to focus on the technical issues of single-stage thermo-electric coolers (TECs) and two-stage TECs and then apply new methods in optimizing the dimensions of TECs. In detail, some metaheuristics—simulated annealing (SA) and differential evolution (DE)—are applied to search the optimal design parameters of both types of TEC, which yielded cooling rates and coefficients of performance (COPs) individually and simultaneously. The optimization findings obtained by using SA and DE are validated by applying them in some defined test cases taking into consideration non-linear inequality and non-linear equality constraint conditions. The performance of SA and DE are verified after comparing the findings with the ones obtained applying the genetic algorithm (GA) and hybridization technique (HSAGA and HSADE). Mathematical modelling and parameter setting of TEC is combined with SA and DE to find better optimal findings. The work revealed that SA and DE can be applied successfully to solve single-objective and multi-objective TEC optimization problems. In terms of stability, reliability, robustness and computational efficiency, they provide better performance than GA. Multi-objective optimizations considering both objective functions are useful for the designer to find the suitable design parameters of TECs which balance the important roles of cooling rate and COP.

Applications of Hybrid Photovoltaic Modules with Thermoelectric Cooling

Among the energy sources with low efficiency, thermoelectric systems are used for hybrid systems with improved performance. This paper provides a review of recent literature concerning the integration of ThermoElectric Cooling (TEC) devices into PhotoVoltaic (PV) generators to constitute PV-TEC systems. The role of TEC is to reduce the temperature of the PV cells, to increase the efficiency of the system, its power capacity and lifetime. The paper also contains a formulation of thermoelectric module equations referring to cooling capacity, rate of heat rejected to the ambient and input power, together with the electrical model of the PV generator.

Fabrication and Characterization of Brush-Printed p-Type Bi0.5Sb1.5Te3 Thick Films for Thermoelectric Cooling Devices

Bismuth telluride alloys are promising thermoelectric materials used for portable␣and wearable cooling devices due to their excellent thermoelectric properties near the ambient temperature. Here, a simple and cost-effective brush-printing technique, together with a subsequent annealing treatment, has been used to prepare Bi2Te3-based thick films and prototype devices. The composition, microstructure, and electrical properties of the brush-printed p-type Bi0.5Sb1.5Te3 thick films at different annealing temperatures are investigated. It is found that annealing temperature plays an important role in promoting densification and preventing the film from cracking, hence improving the electrical transport properties. The maximum power factor of the brush-printed thick films is 0.15 mW K−2 m−1 when annealed at 673 K for 4 h. A prototype thermoelectric device is manufactured by connecting the brush-printed p-type Bi0.5Sb1.5Te3 and n-type Bi2Te2.7Se0.3 thick films with Cu thick-film electrodes on an Al2O3 substrate. The cooling performance of the thermoelectric device is evaluated by measuring the temperature difference produced under applied currents.

Dimensionless Model of a Thermoelectric Cooling Device Operating at Real Heat Transfer Conditions: Maximum Cooling Capacity Mode

Real operating conditions of a thermoelectric cooling device are in the presence of thermal resistances between thermoelectric material and a heat medium or cooling object. They limit performance of a device and should be considered when modeling. Here we propose a dimensionless mathematical steady state model, which takes them into account. Analytical equations for dimensionless cooling capacity, voltage, and coefficient of performance (COP) depending on dimensionless current are given. For improved accuracy a device can be modeled with use of numerical or combined analytical-numerical methods. The results of modeling are in acceptable accordance with experimental results. The case of zero temperature difference between hot and cold heat mediums at which the maximum cooling capacity mode appears is considered in detail. Optimal device parameters for maximal cooling capacity, such as fraction of thermal conductance on the cold side y, fraction of current relative to maximal j′ are estimated in range of 0.38–0.44 and 0.48–0.95, respectively, for dimensionless conductance K′ = 5–100. Also, a method for determination of thermal resistances of a thermoelectric cooling system is proposed.