Thermoelectric Heat Research Articles

Design of A Thermoelectric Generator for Battery Charging using Heat from A Steam Iron Base

This study explores an alternative method of generating electrical energy using a thermoelectric generator that utilizes heat from the soleplate of a steam iron and six thermoelectric units connected in series. Based on the Seebeck effect, the thermoelectric modules convert the temperature difference into voltage. An increase in the heat source temperature leads to higher voltage production by the series-connected thermoelectric modules, although the electrical power output depends on the connected load. The power generator design includes thermoelectric modules, a buck-boost converter, an 18650 lithium-ion battery, and a 5-watt, 12-volt DC lamp. The study addresses key aspects such as the impact of temperature on power output in series-connected and parallel-connected thermoelectric circuits, and the efficient conversion of heat from the steam iron soleplate into electrical energy. The research objectives are threefold: to determine power and temperature values for series-connected thermoelectric circuits, to evaluate power and temperature values for parallel-connected thermoelectric circuits, and to utilize heat from the steam iron soleplate as a thermoelectric heat source for generating electrical energy. Testing involved a buck-boost converter connected to a battery, producing 12.35 volts with a temperature difference of 49°C. Design enhancements, such as integrating heatsinks or coolers on the cold side of the modules to maintain a significant temperature differential, are critical for optimizing performance.

Design and Analysis of a Two-Stage Cascade System for Heating and Hot Water Production in Nearly Zero-Energy Buildings Using Thermoelectric Technology

This paper proposes an innovative system that integrates two thermoelectric heat pumps (one air–water and the other water–water) with two thermal storage tanks at different temperatures to provide heating and domestic hot water to a 73.3 m2 passive-house-certified dwelling in Pamplona (Spain). The air–water thermoelectric heat pump extracts heat from the ambient air and provides heat to a tank at intermediate temperature, which supplies water to a radiant floor. The water–water heat pump takes heat from this tank and provides heat to the other tank, at higher temperature, which supplies domestic hot water. The system performance and comfort conditions are computationally analyzed during the month of January under the climate of Pamplona and under different European climates. The COP of the system lays between 1.3 and 1.7, depending on the climate, because of the low COP of the air–water thermoelectric heat pump. However, it is able to provide water for the radiant floor and to maintain the temperature of the dwelling above 20 °C 99.8% of the time. Moreover, it provides domestic hot water at a temperature above 43 °C 99.9% of the time. Noteworthy is the fact that the water–water heat pump presents a COP close to 4, which opens up the possibilities of working in combination with more efficient heat pumps for the first stage.

The Question of Thermoelectric Devices (TEDs) In/Efficiency—A Practical Investigation Considering Thermoelectric Heaters (TEHs)

ABSTRACTThermoelectricity is a promising technology; however, though clean and versatile, its efficiency has been questionable and consequently limiting its extensive utilization. Many published research on thermoelectricity have been on power generation and cooling applications, with few publications on heating, especially practically. Thus, this article practically focuses on thermoelectric devices (TEDs) when used as thermoelectric heaters (TEHs). Sixteen identical TEDs (TEC‐12706) were operated as TEHs under similar test modalities and powered in succession with 12, 10, 8, 6, and 4 V, to practically examine TEHs energy dynamics and in/efficiency. It was found that all the TEHs used in the research performed relatively inconsistent with each other with the worst‐performed TEH (TEH0) having a mean hot‐side temperature of 30.276°C with a mean power consumption of 13.826 W; whereas the best‐performed TEH (TEH3) had a mean hot‐side temperature of 40.4°C with a mean power consumption of 20.822 W. Furthermore, all the TEHs hot‐side temperature increased proportionately with the input voltage; though at the specified voltages, the TEHs hot‐side temperature increased while its input power decreased over time. The concepts of TEH hot‐side mean temperature and TEH mean input power were also introduced.

Optimization of microwave-assisted biodiesel production using response surface methodology

Energy stands as the fuel of the human activities, and with finite fossil fuels, biodiesel has become a promising, eco-friendly alternative. Microwave technology is emerging as one of the most efficient biodiesel production methods. The primary goal of this work is to optimize the microwave-assisted production of biodiesel and improve its productivity using response surface methodology. A modified microwave oven with built-in stirring system and temperature measurement significantly reduces the reaction time compared to traditional thermoelectric heating. Numerous factors impact microwave-assisted biodiesel production, encompassing catalyst type and concentration, microwave power, reaction temperature, alcohol type, alcohol-to-oil molar ratio, water content, and stirring rate. Hence, acquiring a comprehensive understanding of how these variables affect the biodiesel production becomes imperative. Response surface methodology was utilized to improve the biodiesel microwave-assisted production yield of sunflower oil involving ethanol as alcohol and NaOH as catalyst. The impact of the ethanol-to-oil ratio, the catalyst amount and the reaction temperature on biodiesel production yield was investigated. Results demonstrated that the temperature had the most significant impact on biodiesel production, with an optimal temperature of 70 °C. The highest biodiesel yield, of 98.4%, was obtained at an alcohol-to-oil ratio of 6:1 and 2% by mass of sodium hydroxide.

Unraveling the Synergistic Role of Kinks in Zig-Zag Ag2Se Nanorod Arrays for High Room-Temperature zT and Improved Mechanical Properties: Experimental and First-Principles Studies.

Flexible thermoelectric materials are usually fabricated by incorporating conducting or organic polymers; however, it remains a formidable task to achieve high thermoelectric properties comparable to those of their inorganic counterparts. Here, we present a high zT value of 1.29 ± 0.31 at room temperature in the hierarchical zig-zag Ag2Se nanorod arrays fabricated using the glancing angle deposition (GLAD) technique followed by a facile selenization process. The high zT value at 300 K is ascribed to the ultrahigh power factor of 3101 ± 252 μW/m-K2 and the reduced thermal conductivity of 0.72 ± 0.01 W/mK. Based on ab initio computational and experimental evidence, we reveal that kinked Ag2Se nanorod arrays consisting of rough interfaces modulate the lattice thermal conductivity up to 48.5% at room temperature. The modulation results from interchanging of phonon modes at kink points and enhanced scattering from a large number of rough interfaces. Further, benefiting from kinked hierarchy, a notable improvement in the mechanical performance is observed for zig-zag Ag2Se nanorods which is confirmed by nanoindentation measurements. The synergic improvement in thermoelectric and mechanical performance not only unravels a paradigm to harness thermoelectric heat but also offers deeper insights into tuning the mechanical properties of inorganic thermoelectric materials.

Information Arbitrage in Bipartite Heat Engines

Heat engines and information engines have each historically served as motivating examples for the development of thermodynamics. While these two types of systems are typically thought of as two separate kinds of machines, recent empirical studies of specific systems have hinted at possible connections between the two. Inspired by molecular machines in the cellular environment, which in many cases have separate components in contact with distinct sources of fluctuations, we study bipartite heat engines. We show that a bipartite heat engine can produce net output work only by acting as an information engine. Conversely, information engines can extract more work than the work consumed to power them only if they have access to different sources of fluctuations, i.e., act as heat engines. We illustrate these findings first through an analogy to economics and a cyclically controlled 2D ideal gas. We then explore two analytically tractable model systems in more detail: a Brownian-gyrator heat engine, which we show can be reinterpreted as a feedback-cooling information engine, and a quantum-dot information engine, which can be reinterpreted as a thermoelectric heat engine. Our results suggest design principles for both heat engines and information engines at the nanoscale and ultimately imply constraints on how free-energy transduction is carried out in biological molecular machines. Published by the American Physical Society 2024

Enhancing the Performance of Photovoltaic Solar Cells using a Hybrid Cooling Technique of Thermoelectric Generator and Heat Sink

Abstract This study aims to enhance the performance of photovoltaic (PV) solar cells by employing a hybrid cooling technique involving a thermoelectric generator (TEG) and heat sink. Three configuration modules are investigated both experimentally and numerically: module 01: PV only (PV), module 02: PV with TEG (PV-TEG), and module 03: PV with TEG and heat sink (PV-TEG-HS). These modules have been examined numerically under various weather conditions, including solar radiation, wind speed, and ambient temperature. The experimental and numerical results indicate that as solar radiation increases from 500 to 1000 W/m2, the temperature of the PV back sheet and PV solar cell also increases. Specifically, for module PV, module PV-TEG, and module PV-TEG-HS, the temperature increases by 57.3%, 56.1%, and 32% respectively. Additionally, the percentage output power (Pout) of the PV increases with rising solar radiation for the three modules, reaching 60.5%, 62.0%, and 87.39% respectively. Moreover, the percentage Pout of the TEG also increases with the increasing solar radiation for the three modules, with percentages of 0%, 299.25%, and 311.96% respectively. Furthermore, increasing wind speed leads to a decrease in the temperatures of the back sheet and solar cell, while simultaneously increasing the Pout of the PV for all three modules. However, the Pout of the TEG in module PV-TEG-HS decreases. The impact of increasing ambient temperatures on module PV-TEG-HS is relatively small compared to the other modules.

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.

Fast-airflow tumble clothes dryer with small thermoelectric heat pump: Experimental evaluation

Residential clothes drying accounts for about 5 % of the total residential-sector energy consumption in the United States. Most dryers use electric resistance heaters to dry clothes and have low efficiencies. Higher-efficiency dryers that use vapor compression heat pumps are expensive and complex and have not gained a large market share in the United States. A novel tumble clothes dryer using a small thermoelectric heat pump with faster airflow than typical dryers is presented in this work. The benchtop performance of the thermoelectric heat pump and high-speed blower are presented, and the development of the prototype dryer is described. The dryer was tested for efficiency and dry time for a range of airflow rates and applied currents to the thermoelectric heat pump. The combined efficiency factor was 5.09–6.29 lbBDW/kWh (specific moisture extraction rate of 1.23–1.53 kgw/kWh) with 100–138 min dry times for these tests. The measured efficiency was 36 %–68 % greater than the minimum efficiency standard in the United States, and compared with vapor compression heat pump–based clothes dryers, the prototype dryer had less expensive, less complex components and did not use refrigerants. The performance of this small thermoelectric heat pump clothes dryer is also compared with previous iterations of the thermoelectric tumble clothes dryer described in the literature.

Analysis of thermotechnical characteristics of the thermoelectric film heating system

Modern world trends in increasing the energy efficiency of heat supply systems, in particular, are aimed at decentralizing the supply of heat to consumers, and also involve the use of low-temperature heating systems. The Institute of Technical Thermophysics of the National Academy of Sciences of Ukraine together with the specialists of the Department of Thermal and Alternative Energy of the National Technical University of Ukraine “Ihor Sikorskyi Kyiv Polytechnic Institute” carried out scientific research and analysis of the main thermal characteristics of the electrothermal film heating system (model ZHDM-WM-220-180 /225/270) and accessories for it manufactured by ZHONGHUI (HEILONGJIANG) UNDERGROUND HEATING CORPORATION (People's Republic of China). The results of the study of the main thermal technical characteristics of the thermoelectrical film heating system are given. The analysis of the design of the heat-dissipating mat showed relatively high reliability of its components and acceptable operational characteristics for various objects of the housing and communal economy.

Solar thermal cooking device for domestic cooking applications: Bridging sustainable development goals and innovation

Fossil fuels are vital in the cooking field rather than the automotive sector. Hence, solar cooking has been popularized in recent years due to the rising cost of cooking gas. However, implementing successful renewable energy for cooking in urban area is still challenging for industries. Hence, a solar thermic cooking device with a compact size suited for domestic cooking in urban area is proposed. Thus, the solar cooking device will be developed as a fully functional prototype with necessary supporting modules, depending on the heat transfer fluid (HTF) flow and heat transfer rate between fluids. The main objective is to represent various computational fluid dynamics (CFD) and thermal analysis results on different optimistic designs for a solar thermoelectric cooking device's heat exchanger and storage unit. The 3D part model of the modules has been developed using SOLIDWORKS 2019 software. CFD has also been carried out using the same workspace with an additional package called flow simulation to analyze the flow properties of heat transfer fluid at different rates when circulated in other modules.Moreover, the thermal behavior of the HTF concerning the heat transition between module surfaces is simulated using SOLIDWORKS flow simulation to evaluate the heat storage capacity and rate of heat transfer. The theoretical formulations for the modules are derived through thermodynamic equations concerning the materials and fluid involved in the unit. The thermal and CFD analysis is carried out for different optimistic 3D models based on thermal sustainability, and the results are compared with theoretical analysis, which is discussed in this paper.

Tunable thermoelectric superconducting heat pipe and diode

Abstract Efficient heat management at cryogenic temperatures is crucial for superconducting quantum technologies. This study demonstrates the controlled manipulation of the heat flow and heat rectification through an asymmetric superconducting tunnel junction. The system exhibits a non-reciprocal behavior, developing a thermoelectric regime exclusively when the electrode with the larger gap is heated. This feature significantly boosts thermal rectification effectively classifying the device as a heat diode. At the same time when operating as a thermoelectric engine, the same device also functions as a heat pipe, expelling heat from the cryogenic environment, minimizing losses at the cold terminal. This dual functionality is inherently passive, and the performance of the heat pipe and the heat diode can be finely adjusted by modifying the external electrical load.

Advancements in Nanotechnology‐Based PEDOT and Its Composites for Wearable Thermoelectric Applications

Thermoelectric materials’ unique merits attract considerable attention. Among those merits, the straight transformation between heat and electricity makes this material potential. The energy of the human body is released in the form of heat, which can be transformed into effective electricity by wearable thermoelectric materials. The nanotechnology‐based materials improve thermoelectric properties and heat absorption abilities for nanostructures will help maintain good electrical conductivity and reduce thermal conductivity. Poly(3,4‐ethylenedioxythiophene) (PEDOT) is extensively investigated for its high conductivity, flexibility, good transparency, and so on. This article reviews its mechanism and describes the preparation techniques and thermoelectric properties of nanotechnology‐based PEDOT, inorganic semiconductor composite, and low‐dimensional metal composite thermoelectric materials. The recent research progress on PEDOT‐based thermoelectric materials, the application of wearable low‐dimensional PEDOT‐based thermoelectric materials, and methods to improve the thermoelectric performance of PEDOT‐based composite materials, device design, and commercialization are specifically discussed.

Development and Experimental Validation of a Two-stage Thermoelectric Heat Pump Computational Model for Heating Applications

The utilisation of thermoelectric technology as a heat pump in heating applications necessitates comprehensive investigation. The scalable nature of thermoelectric technology enables its operation at elevated temperatures without the requirement of refrigerants. In this work, an accurate computational model that can simulate one- and two-stage thermoelectric heat pumps is developed. This model uses the electric-thermal analogy and the finite difference method, including the thermoelectric effects, temperature dependent properties, thermal contact resistances and all heat exchangers, even the intermediate heat exchanger in the case of a two-stage configuration. Moreover, the model has been experimentally validated by built and tested prototypes, being the first time that a two-stage thermoelectric heat pump model is experimentally validated.The discrepancy between the simulated and experimental results is below the ± 10 % for COP, ± 8 % for generated heat and temperature lift in the airflow, and less than the ± 6 % for consumed power. Additonally, the model simulates real tendencies under different operating conditions, proving the reliability of the developed thermoelectric heat pump model.Finally, the model is used to optimise a thermoelectric system combining one- and two-stage thermoelectric heat pumps, and hybridising them with electric resistances. An airflow of 16.5 m3/h is heated from 25 °C to 160 °C, achieving a maximum COPtot of 1.21. Lastly, the importance of considering the thermal resistances of the heat exchangers is computationally modelled and demonstrated. Not taking them into account would overestimate the performance of the TEHP system by more than the 7 %.

Raising the Drying Unit for Fruits and Vegetables Energy Efficiency by Application of Thermoelectric Heat Pump

Drying food stuffs and other materials belongs to one of the most commonly used feedstock processing techniques, featuring rather high energy consumption. The major disadvantage of conventional electric convective-type household dryers is substantial thermal energy emission into the environment with a wet exhaust, worked-out drying agent. Among other principal disadvantages common to all dryers of this type, the following have to be mentioned: spatial inhomogeneity of heating a product under processing and that of drying agent distribution due to its temperature reduction and relative humidity growth as it moves upwards. A block diagram and a breadboard model of a convective-type thermoelectric dryer employing a thermoelectric heat pump have been designed. In our approach, a product is treated with the help of a drying agent (normally, heated air) with partial exhaust-air recirculation and heat recovery. Laboratory studies of the drying process have been carried out using apple fruits as a test material in order to evaluate the power consumed for evaporation of 1 kg of water in the newly developed convective-type thermoelectric drying unit. Physical parameters of apple fruits before and after drying both in the thermoelectric drying unit and in a conventional series-produced convective-type domestic dryer have been reported. The energy efficiency of the newly designed drying unit has been compared with that of some series-produced samples. It has been found out that, unlike conventional convective-type dryers, the breadboard model of the developed thermoelectric drying unit features a smoother product drying process owing to the presence of side air channels and more effective drying agent path organization in the processing chamber. This conclusion was supported by the results of the carried out tests. Application of thermoelectric heat pumps with the function of the exhaust drying agent heat recovery will make it possible to reduce the drying agent heater installed capacity and the power consumed by the newly designed convective-type thermoelectric drying unit by up to 20% in the course of the drying process, compared to series-produced household convective-type dryers.

Modulating Thermal Conductivity via Targeted Phonon Excitation.

Thermal conductivity is a critical material property in numerous applications, such as those related to thermoelectric devices and heat dissipation. Effectively modulating thermal conductivity has become a great concern in the field of heat conduction. Here, a quantum modulation strategy is proposed to modulate the thermal conductivity/heat flux by exciting targeted phonons. It shows that the thermal conductivity of graphene can be tailored in the range of 1559 W m-1 K-1 (decreased to 49%) to 4093 W m-1 K-1 (increased to 128%), compared with the intrinsic value of 3189 W m-1 K-1. The effects are also observed for graphene nanoribbons and bulk silicon. The results are obtained through both density functional theory calculations and molecular dynamics simulations. This novel modulation strategy may pave the way for quantum heat conduction.

Heating performance of a vapor compression heat pump cascaded with a thermoelectric heat pump

Air source heat pumps (ASHPs) are widely utilized for heating and cooling in residential buildings; however, their effectiveness in heating mode is compromised during extreme weather conditions. Extensive research endeavors have been undertaken to develop, test, and assess a cost-effective vapor compression ASHP suitable for cold climate regions. This study takes an innovative approach by developing component and system prototypes for a cold climate heat pump. This design combines a thermoelectric heat pump (TEHP) with a traditional residential split ASHP to augment heating capacity in low ambient temperature conditions. The component and system prototypes underwent experimental testing in the psychrometric chambers. The experimental findings revealed a 13.6 % to 13.7 % increase in total heat pump heating capacity, accompanied by a 3.1 % to 5.0 % decrease in the coefficient of performance (COP) at ambient temperatures of −15 °C and −19 °C, when compared to the original ASHP. The COP of the TEHP is relatively constant, ranging from 1.63 to 1.76. This prototype offers a solution to address the challenges associated with reduced heat pump capacity at low ambient temperatures. The experimental results indicated that the lower the ambient temperature, thermoelectric heat pump auxiliary heating can increase the heating efficiency 60 % in comparison to electric resistance.

Experimental and numerical study on photovoltaic thermoelectric heat storage system based on phase change temperature control

To improve the thermal and electrical performance of photovoltaic (PV) systems, a novel system was proposed, in which the PV panel, phase change material (PCM), thermoelectric (TE), and thermal collection devices (PV-PCM-TEG-T) were combined. The experimental device of the PV-PCM-TEG-T system was put up, and its electrical and thermal characteristic was experimentally studied by comparing it with the standard PV panel on the condition of 3-hour radiation and 3-hour non-radiation. A heat transfer numerical model of the PV-PCM-TEG-T system is established and verified by experiments. The comparison of the PV-PCM-TEG-T system and standard PV panel and the effects of PCM thicknesses, and melting temperatures on the temperature of photovoltaic devices were numerically analyzed in 24-hour operating conditions. The results show that under an experimental condition of 3-hour solar radiance of 800 W/m2 and 3-hour non-radiance, the novel system has better temperature control performance, which could increase the PV panel’s output power and power generation efficiency by 10.4 % and 1.9 % respectively. Under 24-hour simulation conditions, the temperature of the novel system is significantly lower than that of the standard PV panel, with a maximum temperature difference of 10.1 °C. The PV-PCM-TEG-T system with thicker PCM has the same temperature as the system with thinner PCM, but higher TE power generation. And the temperature control is better with the lower PCM melting point. This study has a good promoting effect on the efficient utilization of solar energy.

Enhanced Heat Transfer in Thermoelectric Generator Heat Exchanger for Sustainable Cold Chain Logistics: Entropy and Exergy Analysis

This study investigates the application of thermoelectric power generation devices in conjunction with cold chain logistics transport vehicles, focusing on their efficiency and performance. Our experimental results highlight the impact of thermoelectric module characteristics, such as thermal conductivity and the filling thickness of copper foam, on the energy utilization efficiency of the system. The specific experimental setup involved a simulated logistics cold chain transport vehicle exhaust waste heat recovery thermoelectric power generation system, consisting of a high-temperature exhaust heat exchanger channel and two side cooling water tanks. Thermoelectric modules (TEMs) were installed between the heat exchanger and the water tanks to use the temperature difference and convert heat energy into electrical energy. The analysis demonstrates that using high-performance thermoelectric modules with a lower thermal conductivity results in better utilization of the temperature difference for power generation. Additionally, the insertion of porous metal copper foam within the heat exchanger channel enhances convective heat transfer, leading to an improved performance. Furthermore, the study examines the concepts of exergy and entropy generation, providing insights into the system energy conversion processes and efficiency. Overall, this research offers valuable insights for optimizing the design and operation of thermoelectric generators in cold chain logistics transport vehicles to enhance energy utilization and sustainability.

Thermodynamic analysis of drying cycles utilizing a desiccant wheel thermoelectric modules and heat pipe for the drying of hazel nuts in the East Blacksea climatic conditions

The use of renewable energy sources to maintain appropriate thermal humidity and temperature conditions in food drying technologies, especially in humid climate zones, is a current area of research. In the Eastern Black Sea Region, the high relative and specific humidity of the atmospheric air lead to a low drying rate of the products. Therefore, in this study, to enhance the drying rate of the products, three models and their psychometric cycles were studied on decreasing the specific humidity of the drying air and increasing the moisture saturation degree of the drying air. The innovative hazelnut drying models proposed for the climatic conditions of the Eastern Black Sea region incorporate several components, including thermoelectric modules (TEM), photovoltaic thermal (PV/T) systems, desiccant wheels (DW), heat pipes (HP) and heat exchangers (HX). The thermodynamic analysis was conducted on the theoretical cycles belonging proposed models. Emphasis was given to the development of Model-C, taking into account the drying conditions specific to hazelnuts in the Eastern Black Sea region, among the cycles named Model-A, Model-B and Model-C. The energy efficiencies and SEMER values of Model-A, Model-B and Model-C were presented based on selected atmospheric conditions. Each model is valid under its characteristic operating conditions, and the energy efficiencies, SEMER values and the exergetic efficiencies for Model-A, Model-B and Model-C were determined as (4.66%-0.271 kg-H2O kWh−1–62%), (9.87%-0.1542 kg-H2O kWh−1–22%) and (9.13%-0.1381 kg-H2O kWh−1–10%), respectively. Also, presented models of hazelnut drying supported by renewable energy have achieved high sustainable index (SI) values. Consequently, these models ensure the sustainability of energy in the drying sector and facilitate the assessment of their environmental, economic and social impacts. The utilization of renewable energy in the models will lead to a reduction in CO2 emissions during the drying process. These results indicate that TEM systems are a viable option for food drying in the future.