Thermoelectric Chip Research Articles

Form-Stable Composite Phase Change Materials Based on Porous Copper-Graphene Heterostructures for Solar Thermal Energy Conversion and Storage.

Solar-thermal energy conversion and storage technology has attracted great interest in the past few decades. Phase change materials (PCMs), by storing and releasing solar energy, are able to effectively address the imbalance between energy supply and demand, but they still have the disadvantage of low thermal conductivity and leakage problems. In this work, new form-stable solar thermal storage materials by impregnating paraffin PCMs within porous copper-graphene (G-Cu) heterostructures were designed, which integrated high thermal conductivity, high solar energy absorption, and anti-leakage properties. In this new structure, graphene can directly absorb and store solar energy in the paraffin PCMs by means of phase change heat transfer. The porous structure provided good heat conduction, and the large surface area increased the loading capacity of solar thermal storage materials. The small pores and superhydrophobic surfaces of the modified porous G-Cu heterostructures effectively hindered the leakage issues during the phase change process. The experimental results exhibited that the thermal conductivity of the prepared form-stable PCM composites was up to 2.99 W/(m·K), and no leakage took place in the solar-thermal charging process. At last, we demonstrated that the PCM composites as an energy source were easily integrated with a thermoelectric chip to generate electric energy by absorbing and converting solar energy.

Chip-scale solar thermal electrical power generation

There is an urgent need for alternative compact technologies that can derive and store energy from the sun, especially the large amount of solar heat that is not effectively used for power generation. Here, we report a combination of solution- and neat-film-based molecular solar thermal (MOST) systems, where solar energy can be stored as chemical energy and released as heat, with microfabricated thermoelectric generators to produce electricity when solar radiation is not available. The photophysical properties of two MOST couples are characterized both in liquid with a catalytical cycling setup and in a phase-interconvertible neat film. Their suitable photophysical properties let us combine them individually with a microelectromechanical ultrathin thermoelectric chip to use the stored solar energy for electrical power generation. The generator can produce, as a proof of concept, a power output of up to 0.1 nW (power output per unit volume up to 1.3 W m−3). Our results demonstrate that such a molecular thermal power generation system has a high potential to store and transfer solar power into electricity and is thus potentially independent of geographical restrictions.

(Invited) Ultra-Thin MEMS Thermoelectric Chip and Its Applications

Ultra-thin MEMS Thermoelectric Chip and Its ApplicationsZhiyu HuInstitute NanoMicroEnergy, Department of Micro/Nano-ElectronicsShanghai Jiao Tong University, Shanghai, China, 200240Email: zhiyuhu@sjtu.edu.cn : For a long time, mankind has been seeking inexhaustible energy in nature. There is an urgent need to obtain new types of sustainable, environmentally friendly and green energy to reduce our dependence on petrochemical energy. The thermoelectric generator (TEG) can directly convert heat into electrical energy through the Seebeck effect, thereby obtaining electrical energy, which makes it a promising environmentally friendly energy conversion method. TEG has many special advantages, such as no moving parts, no pollution, no noise, no mechanical vibration, etc. At present, all TEGs on the market is made with traditional method which yields high cost, low efficiency, not suitable for massive and economic production.Thermoelectric generator (TEG) can directly convert heat into electrical energy. Due to its special advantages, such as no pollution, no noise, no mechanical vibration, etc., TEG has been widely used in vehicles, wearable devices, solar energy systems, and industrial waste heat recovery systems. In order to promote the application of thermoelectric devices, it is necessary to improve the performance of thermoelectric materials through nanostructures. Generally, thermal resources are concentrated on increasing the temperature at the hot end of the TEG. In this article, the heat in the environment is pumped into the external space through radiant cooling (RC), thereby generating the cold end of the TEG and a continuous self-powered system was obtained.Taking advantages of micro/nano-fabrication and the scale effects of heat theory, we are able to design and build a thermoelectric chip in a large array and maintain a stable temperature difference between sub-micrometer-thick of a thermoelectric unit on a silicon wafer. The submicron-thick TEG containing more than 46,000 thermoelectric modules in series was fabricated on SiO2/Si. The combined Seebeck coefficients of Sb2Te3 and Bi2Te3 were adopted the average value which were evaluated to be 250 μV/K. The details of the fabrication method were proposed first and demonstrated in our previous work.Nanostructured multilayer thermoelectric films have been developed to improve thermoelectric efficiency. The effects of interface microstructure on the cross-plane thermal conductivities of the multilayer thin films have been extensively examined and the thermal transfer mechanism has been explored. Experimental results indicate that ultrathin thermoelectric device works stable and reliable, and is suitable for fabrication of thinner and higher integrality devices in mass production.We have demonstrated a novel energy utilization that MEMS-based thermoelectric chip can produce electricity by radiative cooling (RC) in day and night. Thermal emitter composed evaporated Ag layer and 12 alternating SiO2 and Si3N4 layer periods deposited on a silicon by plasma enhanced chemical vapor deposition (PECVD). The absorptivity of the thermal emitter is 80.8%. Here, the emission is caused by phonon-polaron excitation in the Si3N4 layer. SiO2 was chosen to fully reduce the adverse radiation loss because it has an absorption peak close to 9 μm in the atmospheric window due to its phonon-polaron resonance. The silver-plated layer can enhance the electromagnetic wave reflection without resonance.In addition, the MOST material that collected solar energy in Gothenburg，Sweden has been delivered to Shanghai, China by express mail, and successfully generated electricity on the MEMS TE chip a few months later.MEMS-based thermoelectric chips can use ultra-low thermal energy to directly generate electricity with a very small temperature difference. In future, when such advanced energy technology is wildly available and at very low costs, we then will obtain truly sustainable, completely environmentally friendly clean energy, and greatly reducing our dependence on petrochemical energy. MEMS-based thermoelectric chip can also be used as an ultra-sensitive temperature sensor, several testing examples will be introduced and with further discussions.

Study on the performance of a solid-state thermoelectric refrigeration system equipped with ionic wind fans for ultra-quiet operation

Conventional compression refrigeration systems generate considerable noise and vibration. The noise results in serious, negative impacts on people. Thermoelectric refrigeration technologies are considered a potential way to overcome these challenges. A novel thermoelectric refrigeration system, wherein thermoelectric chips are coupled with ionic wind fans, is proposed. Its performance was experimentally investigated and compared with theoretical results. The actual operating noise of the thermoelectric refrigeration system is only 4.2 dB(A), which is much lower than the maximum noise value that does not affect sleep. From experiments under different operating conditions, the optimal operating voltage of the thermoelectric chip is 5.5 V at 283.15 and 313.15 K on the cold and hot sides. The maximum coefficient of performance (COP) values reaches 0.28 and 0.31, which are equivalent to those of a system coupled with mechanical fans. Additionally, an ionic wind fan has an optimal operating voltage of 10.8 kV to maximize its air supply efficiency. Notably, such an operating voltage might be distinguished from the optimal voltage that achieves maximum operational performance for the new system. When the operating voltage of the thermoelectric chip is 5 V, the optimal operating voltage to obtain a maximum COP of 0.31 is 11.1 kV. Moreover, the experimental refrigeration capacity is greater than 8 W. The new system shows the ultra-quiet ability to operate at a large refrigeration capacity, and has good potential in applications, such as advanced refrigeration, building air-conditioning and ventilation systems.

New Type of Thermoelectric CdSSe Nanowire Chip.

Facing the increasingly serious problem of environmental pollution and energy waste, the thermoelectric generator has been attracting more and more attention owing to its advantages including low cost, no pollution, and good stability. The family of thermoelectric material is constantly extended with enhanced performance. Note that nanostructuring can enhance thermoelectric performance. However, the most recent excellent material with effective thermoelectric transformation reported from bulk materials has definite benefits to the practical application compared to nanomaterials. In this work, a nanostructure integrated macroscale thermoelectric chip, that is an alloyed band gap gradient macroscale chip (1.0 cm × 2.0 cm) composed of CdSSe nanowires, has been proven as an excellent thermoelectric generator for the first time. A high Seebeck coefficient of -152.4 μV/K and the average output voltage of 10.8 mV are obtained after optimizing the electrode patterns and distance between electrodes. More interestingly, upon illumination by white light from a xenon lamp, a photo-thermoelectric output voltage is greatly elevated to 45 mV due to the high concentration of photogenerated carriers. The CdSSe thermoelectric chip also shows good repeatability and high stability with a relative error of <6%. No study on the thermoelectric performance of such an alloyed band gap gradient macroscale chip is mentioned before. The results illustrate a bright avenue to realize a type of light-modulated macroscale thermoelectric chips by nanostructure, allowing such kinds of CdSSe chips to be used to generate electric energy in the near future.

Variable-Temperature Electrospray Ionization for Temperature-Dependent Folding/Refolding Reactions of Proteins and Ligand Binding.

Stabilities and structure(s) of proteins are directly coupled to their local environment or Gibbs free energy landscape as defined by solvent, temperature, pressure, and concentration. Solution pH, ionic strength, cofactors, chemical chaperones, and osmolytes perturb the chemical potential and induce further changes in structure, stability, and function. At present, no single analytical technique can monitor these effects in a single measurement. Mass spectrometry and ion mobility-mass spectrometry play increasingly essential roles in studies of proteins, protein complexes, and even membrane protein complexes; however, with few exceptions, the effects of the solution temperature on the stability and structure(s) of analytes have not been thoroughly investigated. Here, we describe a new variable-temperature electrospray ionization (vT-ESI) source that utilizes a thermoelectric chip to cool and heat the solution contained within the static ESI emitter. This design allows for solution temperatures to be varied from ∼5 to 98 °C with short equilibration times (<2 min) between precisely controlled temperature changes. The performance of the apparatus for vT-ESI-mass spectrometry and vT-ESI-ion mobility-mass spectrometry studies of cold- and heat-folding reactions is demonstrated using ubiquitin and frataxin. Instrument performance for studies on temperature-dependent ligand binding is shown using the chaperonin GroEL.

First Principles Computation on the Photovoltaic and Thermoelectric Properties of MAPbI3-xClx Perovskites

This research employs the first principles computation to simulate the chlorine (Cl) doping effect with different proportion (x value) on the photovoltaic and thermoelectric properties of bulk mixed halide methyl-ammonium lead perovskites (MAPbI3-xClx). In the study, the density functional theory (DFT) and Boltzmann transport equation (BTE) are applied to calculate the optical band gaps, electrical conductivity , carrier thermal conductivity , and Seebeck coefficient S. The density functional perturbation theory (DFPT) and Debye model are used to calculate the phonon thermal conductivity . Tuning the greatest thermoelectric figure of merit (ZT) with suitable solar absorbance range is the major target for our solar thermoelectric chip design. The simulation results reveal that doping Cl will increase the electronic conductivity, phonon thermal conductivity, and causes a blue shift in the light absorption. The main contribution to the total thermal conductivity is mainly from optical phonons, and the main absorbance wavelength locates in the ultraviolet and visible light region (40nm &lt; &lt; 700nm). When x=0.25, MAPbI2.75Cl0.25 achieves the optimized tuning for both light absorption coefficient α and figure of merit ZT in our simulation cases.

Study on a Battery Thermal Management System Based on a Thermoelectric Effect

As is known to all, a battery pack is significantly important for electric vehicles. However, its performance is easily affected by temperature. In order to address this problem, an enhanced battery thermal management system is proposed, which includes two parts: a modified cooling structure and a control unit. In this paper, more attention has been paid to the structure part. According to the heat generation mechanism of a battery and a thermoelectric chip, a simplified heat generation model for a single cell and a special cooling model were created in ANSYS 17.0. The effects of inlet velocity on the performance of different heat exchanger structures were studied. The results show that the U loop structure is more reasonable and the flow field distribution is the most uniform at the inlet velocity of 1.0 m/s. Then, on the basis of the above heat exchanger and the liquid flow velocity, the cooling effect of the improved battery temperature adjustment structure and the traditional liquid temperature regulating structure were analyzed. It can be seen that the liquid cooling structure combined with thermoelectric cooling demonstrates a better performance. With respect to the control system, the corresponding hardware and software were also developed. In general, the design process for this enhanced battery thermal management system can provide a wealth of guidelines for solving similar problems. The H commutation circuit, matrix switch circuit, temperature measurement circuit, and wireless communication modules were designed in the control system and the temperature control strategy was also developed.

A Novel Structural Design of Heat-Dissipation Method for High Brightness LED Lighting with Thermoelectric Chip Module

In various traditional technologies of solving the heat-dissipation problem for LED, all of these methods exhaust the waste heat into the environment and cause the more serious greenhouse effect. In this article, we present a new heat-dissipation method for high brightness 10W LED bulb using a novel structure of thermoelectric chip module. Evidence illustrates that graphite performs both the best heat-absorption material as well as the superior heat-dissipation material for LED thermoelectric chip module. Besides, the double-layered structure with graphite as heat-conduction material of LED thermoelectric module could create the most temperature-difference and thus conduct the highest output power. It implies that double-layered structure of LED thermoelectric chip module with graphite as heat-conduction material is the optimal structure for heat-dissipation of 10W LED bulb.

Reduction of Contact Resistance between NaxCoO2 Thermoelectric Chip and Ag Electrode by Using Spark Plasma Sintering Method.

ABSTRACTNaxCoO2 has a particularly high contact resistance because it forms an insulated layer of NaHCO3 and Na2CO3, which are produced in a chemical reaction with carbon dioxide and water in air on the surface. In this study, we tried to improve the interface resistance between NaxCoO2 and Ag sheet electrodes by connecting these materials with the spark plasma sintering (SPS) technique. The interface resistance between NaxCoO2 and Ag sheet electrodes connected by SPS is compared with that connected with Ag paste. In an experiment, the interface resistance of a sample treated by decrease to less than 1/600 of the former value. It is thought that the NaHCO3 and Na2CO3 insulated layer is decomposed through the application of a large value of applied DC current by using the SPS technique.

Feasibility study of a green energy powered thermoelectric chip based air conditioner for electric vehicles

Traditional compressed-refrigerant air conditioning systems consume substantial energy that may reduce the driving performance and cruising mileage of electric vehicles considerably. It is crucial to design a new climate control system, using a direct energy conversion principle, to further aid in the commercialization of modern electric vehicles. A solid state air conditioner model consisting on TECs (thermoelectric chips) as the load, DSSCs (dye sensitized solar cells) as the renewable energy source and high power LiBs (lithium-ion batteries) as an energy storage device are considered for a personal mobility vehicle. The power management between the main power net and the solid state air conditioner interface is designed with an outer proportional-integral controller and an inner passivity based current controller with a loss included model for perfect tracking. This model is intended to comprise thermal and electrical elements which can be tunable for performance benchmarking and optimization of a solid state air conditioning system. Dynamic performance simulations of the solid-state air conditioner are performed, alongside guidelines for feasibility.

Construction and Analysis of Personalized Air-Conditioning System

This study applied the thermoelectric chip design and the establishment of the personalized air-conditioning system in the design of the single duct and double duct structures. According to the actual measurement results when the ambient temperature was 29°C, the air outlet temperature of the two structures was 22°C, 24°C respectively; the power consumption was 133W, 134W respectively. FLUENT was used to simulate the spatial flow field and temperature field for comparison to learn about the spatial temperature distribution status of the air-conditioning system.

Two dimensional thermoelectric platforms for thermocapillary droplet actuation

Thermocapillary droplet actuation on a substrate is based on the mechanism that droplets can be driven to the cooler regions via surface tension modulation by varying the temperature. The usual method of providing a temperature gradient or temperature difference for thermocapillary droplet actuation is via resistor heaters, in which the rise in temperature can be achieved by increasing the passing currents, yet the cooling function relies on the natural conduction and/or convection. A thermoelectric (TE) chip is advantageous in the temperature control. The heating and cooling functions can be manipulated simply by adjusting the direction of the input current into the TE chip. In this regard, the temperature setting can be precisely feedback-controlled by manipulating the amplitude and direction of current flows. This paper demonstrates the implementation of a two dimensional (2D) TE array for free-surface thermocapillary droplet actuation. The routing, merging, and cutting of droplets are successfully demonstrated on a hydrophobically patterned glass substrate overlaid on the TE array.

The Efficiency of Thermoelectric Chip by Different Heatsink

In this study, aluminum nitride, boron nitride, copper, aluminum, with aluminum extruded heat sink as a cooling way of thermoelectric chip. Heat sink temperature change observed and measured the thermoelectric chip output voltage and current. The results showed that with the aluminum extrusion heat sink will increase the efficiency of thermoelectric chip. Copper + aluminum extrusion heat sink, the average electric power increased 173.93%, while the aluminum + aluminum extruded heat sink mean power increased 212.25 %, while the AlN + aluminum extrusion heat sink fins as mean power increased 197.5 %, And the BN + aluminum extrusion heat sink as a heat sink, the average electric power increased 266.17 %.

The influence of focal brain cooling on neurophysiopathology: validation for clinical application

Focal brain cooling has been recognized to have a suppressive effect on epileptiform discharges or a protective effect on brain tissue. However, the precise influence of brain cooling on normal brain function and histology has not yet been thoroughly investigated. The aim of this study was to investigate the neurophysiopathological consequences of focal cooling and to detect the threshold temperature that causes irreversible histological change and motor dysfunction. The experiments were performed in adult male Sprague-Dawley rats (weighing 250-350 g) after induction of halothane anesthesia. A thermoelectric chip (6 x 6 x 2 mm) was used as a cooling device and was placed on the surface of the sensorimotor cortex after a 10 x 8-mm craniotomy. A thermocouple was placed between the chip and the brain surface. Focal cooling of the cortex was performed at the temperatures of 20, 15, 10, 5, 0, and -5 degrees C for 1 hour (5 rats in each group). Thereafter, the cranial window was repaired. Motor function was evaluated using the beam-walking scale (BWS) every day for 7 days. The rats were killed 7 days after the operation for histological examination with H & E, Klüver-Barrera, glial fibrillary acidic protein, and terminal deoxynucleotidyl transferasemediated deoxyuridine triphosphate nick-end labeling stainings. The authors also euthanized some rats 24 hours after cooling and obtained brain sections by the same methods. The BWS score was decreased on the day after cooling only in the -5 degrees C group (p < 0.05), whereas the score did not change in the other temperature groups. Histologically, the appearance of cryoinjury such as necrosis, apoptosis, loss of neurons, and marked proliferation of astrocytes at the periphery of the lesion was observed only in the -5 degrees C group, while no apparent changes were observed in the other temperature groups. The present study confirmed that the focal cooling of the cortex for 1 hour above the temperature of 0 degrees C did not induce any irreversible histological change or motor dysfunction. These results suggest that focal brain cooling above 0 degrees C has the potential to be a minimally invasive and valuable modality for the treatment of severe brain injury or to assist in the examination of brain function.

Numerical simulation on cerebral cortex cooled by a thermoelectric chip

Numerical simulation on cerebral cortex cooled by a thermoelectric chip

Effective suppression of hippocampal seizures in rats by direct hippocampal cooling with a Peltier chip

The use of focal brain cooling to eliminate epileptic discharges (EDs) has attracted increasing attention in the scientific community. In this study, the inhibitory effect of selective hippocampal cooling on experimental hippocampal seizures was investigated using a newly devised cooling system with a thermoelectric (Peltier) chip. A copper needle coated with silicone and attached to the Peltier chip was used for the cooling device. The experiments were performed first in a phantom model with thermography and second in adult male Sprague-Dawley rats in a state of halothane anesthesia. The cooling needle, a thermocouple, and a needle electrode for electroencephalography recording were inserted into the right hippocampus. Kainic acid (KA) was injected into the right hippocampus to provoke the EDs. The animals were divided into hippocampal cooling (10 rats) and noncooling (control, 10 rats) groups. In the phantom study, the cooling effects (9 degrees C) occurred in the spherical areas around the needle tip. In the rats the temperature of the cooled hippocampus decreased below 20 degrees C within a 1.6-mm radius and below 25 degrees C within a 2.4-mm radius from the cooling center. The temperature at the needle tip decreased below 20 degrees C within 1 minute and was maintained at the same level until the end of the cooling process. The amplitude of the EDs was suppressed to 68.1 +/- 4.8% of the precooling value and remained low thereafter. No histological damage due to cooling was observed in the rat hippocampus. Selective hippocampal cooling effectively suppresses the KA-induced hippocampal EDs. Direct hippocampal cooling with a permanently implantable system is potentially useful as a minimally invasive therapy for temporal lobe epilepsy and therefore could be an alternative to the temporal lobectomy.

Use of a Peltier chip with a newly devised local brain–cooling system for neocortical seizures in the rat

Local cortical cooling for termination of epileptic discharges (EDs) has recently become a focus of research. The authors report on a newly devised cooling system that uses a thermoelectric (Peltier) chip and examine the system's performance in experimental neocortical seizures. Experiments were performed in adult male Sprague-Dawley rats after induction of halothane anesthesia. The Peltier chip was attached to a heat sink with a water channel. Two silicon tubes were connected to the heat sink, and water at 37 degrees C was circulated in the channel. The newly designed device was placed on the surface of the cortex. Kainic acid (KA) was injected into the cortex to provoke EDs. In the nonepileptic cortex, the temperature of the cortical surface decreased to 14.8 +/- 1.5 degrees C and that 2 mm below the surface to 27.1 +/- 3.1 degrees C within 30 seconds after the start of cooling. The temperature of the heated side of the chip was maintained at approximately 36.9 degrees C. Without water circulation, the temperature of the cortical surface decreased to 20 degrees C but soon began to increase, peaking at 30 degrees C. The temperature of the heated side of the chip rose to more than 60 degrees C. The EDs, which appeared within 20 minutes after KA injection, began to decrease in amplitude immediately after cooling began and continued to decrease as the temperature of the cortex was lowered. Sufficient miniaturization and good performance of the cooling device was demonstrated. Further efforts to develop implantable cooling systems and improve existing ones should be continued.