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Precise temperature regulation is a crucial guarantee for many microfluidic analyses. This study presents a linear cooling method of microfluidic chips based on a single TEC, which can achieve synchronous observation of samples. A numerical model was developed and experimentally verified to analyze the temperature responses under different driving current mechanisms of TEC. Based on simulation and experimental analysis, this study proposes to achieve linear cooling based on TEC driven by polynomial function current mechanism. The implementation process is clarified, and the iterative method to obtain the polynomial function current mechanism is provided and elaborated. Using a commercial TEC, the linear cooling of the microfluidic chip from 25.2 °C to −19.7 °C was successfully achieved through both simulation and experiment. The linear cooling rates ranging from 24 °C/min to 41 °C/min with linearity higher than 0.998 were obtained. Moreover, the influencing factors of linear cooling were discussed. It is found that the temperature of the TEC hot side has a significant impact on the linear cooling of the sample cell, while the impact of nitrogen gas temperature is almost negligible. Results also indicate that both the minimum and maximum cooling rates increase as TE-element length increases and TE-element height decreases. [Display omitted] • This work proposes a linear cooling method of microfluidic chip based on TEC. • Linear cooling of microfluidic chip was achieved through simulation and experiment. • Temperature responses of microfluidic chip cooled by TEC were analyzed. • Different driving current mechanisms of TEC were discussed. • Influencing factors and optimization of the linear cooling were discussed. [ABSTRACT FROM AUTHOR]

Electric vehicle alleviates the problems of traditional petrochemical energy consumption. However, its battery thermal management system (BTMS) is still facing the challenges of poor environmental adaptability, large weight, and low work efficiency. A triple-hybrid BTMS with built-in drop-shaped fins is proposed to improve system performance, which integrates composite phase change material (CPCM), thermoelectric cooler (TEC), and cold plate. The impacts of the CPCM thickness, inlet flow rate, fin shape, and density on the system behaviors are investigated. Moreover, cooling and preheating strategies for TEC are designed for ambient temperatures of 75 °C and −20 °C. The results show that can achieve the best comprehensive performance. Compared with the traditional BTMS, the proposed system not only decreases system weight by 6.14 % but also reduces the maximum temperature and maximum temperature difference of the battery by 1.33 °C and 0.61 °C, respectively. When the temperature rises to 75 °C, the piecewise function cooling strategy for TEC can reduce the battery's maximum temperature to 48.86 °C with a low energy consumption. At −20 °C, the quadratic strategy can improve the battery preheating rate to 3.22 °C/min. This investigation will supply a solution for the well-weather-tolerant, lightweight, saving-energy BTMS for electric vehicles. • A triple-hybrid thermal management system is proposed to improve weather tolerance. • Cooling and preheating strategies are designed to reduce system's energy consumption. • Weight decreased by 6.14 % compared with the traditional system with solid cold plates. • A prototype of all-climate thermal management system is manufactured and evaluated. [ABSTRACT FROM AUTHOR]

An efficient thermal regulation strategy is of great significance in ensuring the safe operation of electric vehicles (EVs). However, the commonly used thermal management systems suffer from the problem of not being able to accurately and uniformly control the temperature distribution of lithium-ion batteries (LIBs), which poses great risks to the thermal safety control of batteries. In this paper, an advanced thermal management system for LIBs based on thermoelectric cooler (TEC) was designed to overcome the above problems. First, a temperature regulation mechanism model for LIB was constructed. Then, a novel temperature distribution modeling method for TEC was developed by using spectral method. This modeling process took into account the unsteady heat transfer characteristics, which can achieve high modeling accuracy. Next, a state space model of temperature control was constructed by combining a differential model of LIB with the proposed cooler model. On this basis, a temperature control strategy for LIB using nonlinear model predictive control (NMPC) method was proposed to optimize the cooling process because of its superior processing ability to constraints and nonlinearity. A various of experiments and verifications demonstrated that the presented thermal regulation strategy was effective and feasible. • An advanced thermal regulation system for lithium-ion battery based on thermoelectric cooler is designed. • A novel temperature distribution modeling method for TEC is proposed. • A regulation strategy is developed to control the uniformity of temperature distribution. • The paper provides a good guidance for the application and further study of advanced thermal management system in electric vehicle. [ABSTRACT FROM AUTHOR]

This paper develops three dimensional numerical models of a two-stage series-connected TEC model and a two-stage parallel-connected TEC model. NSGA-II is used to optimize their electric current, height of lower stage and ratio of channel width and thickness of fin in the case of constant thermoelectric material volume. Two objectives, exergy efficiency and irreversibility are considered simultaneously. The optimal values one Pareto front are obtained by three decision making methods, Shannon's entropy, TOPSIS and LINMAP, while deviation index is a criterion for evaluating three decision making methods. Sensitive analysis has been carried out to investigate the influence of three variables to be optimized. And TEC with and without plate-fin heat exchanger have been compared. The results show that solution selected by LINMAP is the most compromising solution. The parallel connected TEC saves about 50% of the power consumption compared to the series connected TEC under the same temperature difference. Optimal variables are discussed to obtain the most energy efficient solution with optimal configuration and plate-fin heat exchanger. • NSGA-II are used to optimize structure, configuration and load resistance of a 2-stage TECs. • Optimal values one Pareto front are obtained by three decision making methods. • LINMAP is the most compromising for selecting the optimized solution. [ABSTRACT FROM AUTHOR]

Abstract Thermoelectric cooler (TEC) is a solid-state component that utilizes Peltier effect to dissipate the heat of the electronic packaging system. It shows unique advantages over conventional cooling technology by quiet operation, long lifetime, and ease of integration. However, the internal heat accumulation caused by Joule heat exposes the TEC to the risk of thermal-mechanical failure during long-term operation in realistic thermal environment. In this paper, a heat-generating chip was employed to the cold-end of the module to serve as the finite thermal load while the heat sink at the hot-end was modeled by heat transfer coefficient. Based on the thermoelectric (TE) and thermal stress analyses, we developed a three-dimensional numerical model of a compact TEC, which took into account the temperature dependent TE material properties. It was found that the thermal load attached to Peltier junction can cause extreme high levels of thermal stress, which might cause dislocations and cracks of the material layers. The influences of electrical current, leg length, ceramic plate and bonding layers on the thermal stress levels were examined. These results presented an optimized design with predictive thermo-mechanical performance to realize minimum thermal stress levels, which provided a useful guide to achieve high reliability in a compact TEC. Highlights • Finite element simulations with temperature-dependent properties are carried out. • The effect of thermal load on the thermo-mechanical performance is investigated. • The effects of current, leg length, ceramic plate and bonding layers are examined. • An optimized design to realize minimum thermal stress levels is provided. [ABSTRACT FROM AUTHOR]

Owing to the advantages of small size, stable operational performance, and precise control of temperature, the thermoelectric cooler (TEC) has been widely applied to electronics, aerospace and other fields where effective thermal management is required. As the critical factors for electrical resistance and thermal resistance, the geometrical dimension and shape have significant impact on the cooling performance and thermal-mechanic characteristics of the TEC, which is investigated hardly in the previous TEC studies. To fill this gap, the paper reports the development and operation of a novel three-dimensional model for the TECs with 10 different leg geometries. Based on the dimensions of a commercial TEC, a simulation was undertaken, thus working out the correlations between the geometry and other relevant parameters, e.g., cooling capacity and COP. Furthermore, the thermal stress of the TEC was investigated to evaluate the impact of the TEC geometrical dimension on its lifespan. Compared to initial TEC leg, the novel module (g) demonstrates a significant cooling capacity improvement, which increase from 0.1429 W to 0.1557 W (18.15 W–19.78 W for device level) by 8.9% under temperature difference of 50 K. Under the extreme working condition, e.g., the Δ T is 90 K, the cooling capacity improved 34.9%, which increase from 0.0286 W to 0.0386 W (3.63 W–4.9 W for device level). • TEC leg geometries with 10 different cross-sections were developed. • A novel geometry improves cooling capacity of 8.9%/34.9% under Δ T = 50/90 K. • Significantly improve cooling capacity reduce thermal stress via novel geometry. • Results provide guides for a new TEC performance optimal direction. [ABSTRACT FROM AUTHOR]

This work developed a three-dimensional, multiphysics, and transient model to investigate transient supercooling of TECs (thermoelectric coolers). The model coupled the heat and electricity conductions and considered all thermoelectric effects. The model was well validated by dynamic test data for a TEC (Thermoelectric cooler) start-up process and was compared with the previous heat conduction model. The comparison confirmed that the multiphysics model has a more superior performance for predicting the key evaluation parameters of the transient supercooling. Then the model was used to investigate various current pulses ( t 0 , t 1/2 , t 1 , t 2 , t 3 , t 4 , and t 5 ) to search for the optimal shape. The results showed that the optimal shape is only determined by the time to reach the minimum cold end temperature ( t min ) and the pulse width ( τ ). For the pulses with t min < τ , a higher power pulse provides a lower cold end temperature, for the pulses with t min = τ , however, the trend is opposite. The present results reasonably explain the divergence for the optimal pulse shape reported by the previous studies. [ABSTRACT FROM AUTHOR]

In the present study, a thermoelectric mini cooler coupling with a micro thermosiphon cooling system has been proposed for the purpose of CPU cooling. A mathematical model of heat transfer, depending on one-dimensional treatment of thermal and electric power, is firstly established for the thermoelectric module. Analytical results demonstrate the relationship between the maximal COP (Coefficient of Performance) and Q c with the figure of merit. Full-scale experiments have been conducted to investigate the effect of thermoelectric operating voltage, power input of heat source, and thermoelectric module number on the performance of the cooling system. Experimental results indicated that the cooling production increases with promotion of thermoelectric operating voltage. Surface temperature of CPU heat source linearly increases with increasing of power input, and its maximum value reached 70 °C as the prototype CPU power input was equivalent to 84 W. Insulation between air and heat source surface can prevent the condensate water due to low surface temperature. In addition, thermal performance of this cooling system could be enhanced when the total dimension of thermoelectric module matched well with the dimension of CPU. This research could benefit the design of thermal dissipation of electronic chips and CPU units. [ABSTRACT FROM AUTHOR]

Abstract: A solar-driven thermoelectric cooling module with a waste heat regeneration unit designed for green building applications is investigated in this paper. The waste heat regeneration unit consisting of two parallel copper plates and a water channel with staggered fins is installed between the solar cells and the thermoelectric cooler. The useless solar energy from the solar cells and the heat dissipated from the thermoelectric cooler can both be removed by the cooling water such that the performance of the cooling module is elevated. Moreover, it makes engineering sense to take advantage of the hot water produced by the waste heat regeneration unit during the daytime. Experiments are conducted to investigate the cooling efficiency of the module. Results show that the performance of the combined module is increased by increasing the flow rate of the cooling water flowing into the heat regeneration water channel due to the reductions of the solar cell temperature and the hot side temperature of the thermoelectric coolers. The combined module is tested in the applications in a model house. It is found that the present approach is able to produce a 16.2 °C temperature difference between the ambient temperature and the air temperature in the model house. [ABSTRACT FROM AUTHOR]

Thermoelectric generator devices, which convert heat directly into electrical power, have a great potential for energy scavenging and green energy harvesting applications. The exploitation of such a potential requires a proper design of both the electrical circuit that drives the electrical load and the thermal part, in particular when the thermoelectric generator is coupled with the hot and cold heat sources through thermal resistances. We propose a straightforward approach to take into account both thermal and electrical issues, by means of an equivalent electric circuit model that can be solved with widely available simulator programs, such as SPICE. Our approach is shown to be effective for supporting the design and optimization of thermoelectric systems from the point of view of the output power and of the efficiency. In particular, with our model we are able to point out that thermal resistance matching optimizes the thermal fluxes only in first approximation: for a particular case study we find that the optimal module thermal resistance is 20% larger than the contact resistance. We also show that the electrical matching for the maximum output power must be carefully considered for each particular thermoelectric module and load condition. • Circuital model for thermoelectric conversion systems. • Design and optimization of a thermoelectric conversion system. • Quantitative comparison between different power management strategies. • Thermal matching conditions with non-ideal heat exchange. • Design of the number of pn elements for a thermoelectric module. [ABSTRACT FROM AUTHOR]

In this work, a novel concept of continuous cooling has been proposed to enhance the super-cooling performance of a two-stage thermoelectric cooler, in which integrated triangular-square pulses are used with their modes separately controlled in the upper and lower stages. The 3-dimensionl modeling of the thermoelectric cooler is developed to simulate the super-cooling performance. The non-dominated Sorting Genetic Algorithm II (NSGA-II) is adopted to perform the multi-parameters optimization of pulses forms, in which twelve influencing parameters including pulse amplitude and width, several time constants such as the interval time and input time of pulses are selected as the searching variables, and maximum effective cooling zone with minimum overshoot temperature is set as the multi-objective function. The optimal designs are proved to be better in super-cooling performance for both constant and variable leg cross-sectional area, owing to their well mutual cooperation of the upper and lower stage pulses. Compared to the conventional design with completely identical imposed current form, the effective cooling zone can be improved up to 72.41% by the optimal design when the cooling load is fixed at 0 kW m-2, and the corresponding temperature overshoot can be decreased by 56.48% from 20.29 K to 8.83 K. • The initiative of integrated pulse is proposed to enlarge the super-cooling effect. • Multi-parameter/objective optimization is conducted to pursue best TEC performance. • Well-coordinated upper and lower pulses are crucial to design a two-stage TEC. [ABSTRACT FROM AUTHOR]

In this paper, the radiative sky cooler (RSC) and thermoelectric cooler (TEC) are integrated to form the RSC-TEC hybrid cooling system that can reduce the TEC required power consumption and increase the system's cooling capacity over a standalone RSC. Specifically, a feasibility study is conducted to evaluate the design and working conditions that allow this system to have superior performance; For example, the TEC module type and number, RSC surface area and radiative emissivity value, solar absorption coefficient and air convective heat transfer coefficient have been parametrically swept to assess their effects on the system's cooling capacity and the TEC power saving coefficient, a metric to define the degree of TEC power consumption reduction due to the RSC. The analyzes have been conducted through a non-dimensional steady-state mathematical model of the hybrid system that cools an enclosed space. Results demonstrate that a 0.1 m2 RSC could reduce the required power consumption of a TEC module (size 4 cm by 4 cm) by up to 10%. Moreover, increasing the RSC surface area further improved the TEC power saving coefficient, but the solar absorption coefficient had to be under 0.02 to maintain a reasonable TEC power saving coefficient. • The radiative sky and thermoelectric coolers are combined into a hybrid cooler. • A feasibility study involving many variables and a steady state model is conducted. • Including the RSC could reduce the TEC power consumption by over 10%. • TEC power saving can be maximized by increasing the RSC versus TEC surface area. • Solar absorption coefficient shall be under 0.02 to ensure reasonable performance. [ABSTRACT FROM AUTHOR]

At present, device engineering has been limited to the rectangular-shaped TE leg. Therefore, a trapezoidal-shaped leg has been proposed for the TE system and prototypes are developed in this work. Performance comparison has been investigated between rectangular and proposed trapezoidal-shaped leg based TE prototypes. The n -type (0.98Bi,0.02Sb) 2 (0.9Te,0.1Se) 3 and p -type (0.25Bi,0.75Sb) 2 (0.95Te,0.05Se) 3 are considered as base material with Durabond-950 binder material to manufacture TE legs by using a cost-effective dispenser printing technology. The current study includes analysis of SEM imaging, characterization of manufactured TE legs, various experimental tests on TE prototypes, comparison between analytical and experimental results, and cost analyses. For the given restricted volume envelope, the trapezoidal-shaped TE prototype generates 1.24 times more voltage and 1.5 times more power when compared to the rectangular-shaped prototype at 30 °C hot side temperature when the cold side is exposed to the surrounding. For a given constant temperature boundary conditions (i.e., Δ T = 10 °C), the rectangular-shaped TE prototype harvests 1.4 times more power than the trapezoidal-shaped one, while the power density for rectangular TE prototype (i.e., 0.37 W/m3) is almost the same as trapezoidal one (i.e., 0.36 W/m3). Furthermore, the proposed trapezoidal-shaped prototype uses 28.6% less material by mass than the rectangular prototype. • Trapezoidal TE leg prototype is manufactured using dispenser printing method. • Trapezoidal TE leg uses 28.6% less material by mass than a rectangular TE leg. • Rectangular TE leg produces more power at isothermal-isothermal boundary condition. • Trapezoidal leg produces more power and voltage at isothermal-convection condition. • Power densities for rectangular and trapezoidal legs are comparable. [ABSTRACT FROM AUTHOR]