Number Of Thermoelectric Modules Research Articles

Performance investigation of new design thermoelectric air conditioning system for electric vehicles

Conventional automobile air conditioning systems use environmentally harmful Chlorofluorocarbons. This method also makes noise and uses a lot of battery energy, making it unsuitable for electric vehicles. So in this paper, the performance of a newly designed cooling system based on the thermo-electric cooling technique installed on the vehicle's roof is proposed and investigated. A complete theoretical transient thermal model based on energy balances is constructed, solved, and validated. The results show an optimum value of the used number of thermoelectric modules, which depends on the input power. This value is 150 for an input power of 200 W and 100 for an input power of 1000 W. At an ambient temperature of 42 °C and without applying a cooling system, moving vehicle with three persons and closed windows, its cabin temperature reaches about 66 °C; in contrast, after applying the TEC system, this temperature reaches around 26 °C at input power 1000 W. The coefficient of performance of the system reduces from about 3 to about 0.85 by increasing the input power from 200 to 1000 W, respectively. Although the coefficient of performance of this system is lower than that of the conventional, it has advantages that make it competitive with conventional air conditioning systems. An economic study based on the Egyptian market shows that the annual cost of the thermo-electric cooling system is lower than that of the conventional one.

Design and Experimental Investigation of a Self-Powered Fan Based on a Thermoelectric System

Providing electricity for isolated areas or emergencies (snowstorms, earthquakes, hurricanes, etc.) is an important challenge. In this study, a prototype of a self-powered fan based on a thermoelectric system was built to enhance the heat dissipation of the thermoelectric generator (TEG) systems using household stoves as heat sources. To improve output performance of the system, a heat collector consisting of a heat-conducting flat plate and a heat sink with fan cooling was designed to integrate several thermoelectric modules (TEM). The effects of the fan operating conditions (airflow velocity), number of thermoelectric modules, electrical connection mode under different heat flux among the performance of the TEG system are studied. The data obtained showed a higher heat flux and lower flow velocity are required to realize self-sustained cooling of the system. The maximum electric power is more sensitive to the heat flux than the fan operation conditions. It is also observed that more modules provide a higher power output but lower efficiency. The maximum power of four modules in series is larger than that in parallel, and the difference between them increases with increasing heat flux of the heat collector. In the case of self-sufficiency: the maximum output power and maximum net power with four thermoelectric modules are 10.92 W and 5.26 W, respectively, at a heat flux of 30,000 W/m2. Additionally, the maximum conversion efficiency of 1.8% is achieved for two modules at a heat flux of 14,000 W/m2, providing an effective strategy for the installation of TEMs and cooling fans in TEG.

Experimental study of thermoelectric generator with different numbers of modules for waste heat recovery

Significant amounts of residual heat are contained in the exhaust of internal combustion engines. In this regard, thermoelectric generation is recognized as one of the techniques with development potential, which renders thermoelectric generators an efficient technology among several waste heat recovery devices. This study involved the construction of an experimental thermoelectric generation system. The effects of the heat source temperature, flow, and number of modules on the thermoelectric performance were experimentally studied. The results show that the output power increases with the number of modules under high-flow conditions. At low flow rates, the optimal number of modules ensures that the system delivers the peak output power. The voltage uniformity coefficient can accurately indicate the uniformity of voltage distribution. The voltage uniformity degrades with an increase in air temperature, but the increase in air flow can improve the voltage uniformity. In addition, with the increase in the number of thermoelectric modules, the voltage inhomogeneity of the module decreases. As the air temperature and flow increase, the power consumption of the thermoelectric generator increases. The resistance power consumption accounts for a large proportion, as much as 24.2%, under high-flow and low-temperature conditions. As the number of modules increases, the resistance power consumption of the thermoelectric generator and the proportion thereof increase. The net output performance is closely related to the number of modules, and under all test conditions, 40 modules achieved a maximum net power generation of 25.16 W, and 16 modules achieved a maximum net conversion efficiency of 1.56%. Therefore, it is necessary to plan the number of modules in the system reasonably. This study provides guidance for the design of high-efficiency thermoelectric generators.

Performance investigation of a two-stage thermoelectric cooler with inhomogeneous materials

A novel model of two-stage thermoelectric cooler with inhomogeneous thermal conductivity in steady-state operating condition is established. The modification of the constant properties model allows controlling the distribution of Joule heat. Considering internal irreversibilities of the thermoelectric cooler, expressions for the cooling capacity, COP, and exergy efficiency are derived. By utilizing numerical methods, the temperature profile along the thermoelectric legs is presented. The optimal operating regions are explored. The COP vs. cooling capacity describing optimal operating regions in inhomogeneity materials are plotted. Meanwhile, the influence of the main parameters such as the variation of thermal conductivity distribution, cold-end temperature and the number of thermoelectric modules on the cooling performance is discussed in detail. Results indicate that the cooling capacity, COP and exergy efficiency are improved compared to those of homo?geneous two-stage thermoelectric coolers when an appropriate inhomogeneous property parameter is applied. The work can provide guidance on design of actual two-stage thermoelectric coolers with inhomogeneous materials.

Numerical and Experimental Investigation of a Thermoelectric-Based Radiant Ceiling Panel with Phase Change Material for Building Cooling Applications

The present paper investigates the performance of a thermoelectric (TE)-based radiant ceiling panel with an additional layer of phase change material (PCM) for building cooling application through numerical and experimental analyses. The design of the ceiling panel consisted of an aluminum sheet with TE modules installed on the back to maintain a relatively low ceiling temperature that provided cooling through radiation and convection. A three-dimensional model was developed in COMSOL Multiphysics, and the system’s performance in several different configurations was assessed. The effect of the number of TE modules, as well as incorporating different amounts of PCM under transient conditions, was investigated for two modes of operation: startup and shutdown. It was shown that for a 609.6 mm × 609.6 mm ceiling panel, the use of four TE modules reduced the average surface temperature down to the comfort range in less than 5 min while producing a relatively uniform temperature distribution across the ceiling panel. It was also shown that the addition of a 2 mm thick PCM layer to the back of the ceiling panel enhanced the system’s performance by elongating the time that it took for the ceiling panel’s temperature to exceed the comfort range when the system shut down, which in turn reduced the number of on/off cycling of the system. The numerical results demonstrated a good agreement with the experimental data. The results from this study can be used for the optimal design of a TE-based radiant ceiling cooling system as a promising technology for smart buildings.

Improvements in the cooling capacity and the COP of a transcritical CO2 refrigeration plant operating with a thermoelectric subcooling system

Restrictive environmental regulations are driving the use of CO2 as working fluid in commercial vapour compression plants due to its ultra-low global warming potential (GWP100 = 1) and its natural condition. However, at high ambient temperatures transcritical operating conditions are commonly achieved causing low energy efficiencies in refrigeration facilities. To solve this issue, several improvements have been implemented, especially in large centralized plants where ejectors, parallel compressors or subcooler systems, among others, are frequently used. Despite their good results, these measures are not suitable for small-capacity systems due mainly to the cost and the complexity of the system.Accordingly, this work presents a new subcooling system equipped with thermoelectric modules (TESC), which thanks to its simplicity, low cost and easy control, results very suitable for medium and small capacity plants. The developed methodology finds the gas-cooler pressure and the electric voltage supplied to the TESC system that maximizes the overall COP of the plant taking into account the ambient temperature, the number of thermoelectric modules used and the thermal resistance of the heat exchangers included in the TESC. The obtained results reveal that, with 20 thermoelectric modules, an improvement of 20% in terms of COP and of 25.6% regarding the cooling capacity can be obtained compared to the base cycle of CO2 of a small cooling plant refrigerated by air. Compared to a cycle that uses an internal heat exchanger IHX, the improvements reach 12.2% and 19.5% respectively.

Heat pipes thermal performance for a reversible thermoelectric cooler-heat pump for a nZEB

The nZEB standards reduce the energy demand of these buildings to a minimum, obtaining this little energy from renewable resources. Taking these aspects into consideration, a thermoelectric cooler-heat pump is proposed to achieve the comfort temperature along the whole year. The same device can provide heat in winter and it can cool down the buildings in summer just by switching the voltage supply polarity. Heat pipes are studied to work on both sides of the thermoelectric modules in order to optimize the heat transfer as these devices present really good thermal resistances and they can work in any position. However, they present pretty different thermal resistances if they work on the cold or on the hot side of the modules. A methodology to thermally characterize these heat exchangers working in both orientations is proposed and a validated computational model is developed to optimize the thermoelectric cooler-heat pump for a nZEB application. The number of thermoelectric modules, the position of the device, the ambient temperature and the air mass flow determine the operation and consequently they need to be studied in order to optimize the application.

Experimental prototype and simulation optimization of micro-radial milliwatt-power radioisotope thermoelectric generator

To satisfy the flexible power demand of the low power dissipation devices in the independent space electric system, a micro-radial milliwatt-power radioisotope thermoelectric generator (RTG) was prepared and optimized in this research. The overall geometrical dimension of the RTG in the experiment was 65mm (diameter)×40mm (height). The RTG, which was built and tested using simulated radioisotope source, eventually obtained an open-circuit voltage of 92.72mV, an electric power of 149.0μW, and an energy conversion efficiency of 0.015% at the ambient temperature of 293.15K and heat source power from 0.1W to 1W. On the basis of the structure used in the experiment, the length and cross-sectional area of the thermoelectric leg and the number of thermoelectric modules were effectively optimized through the COMSOL Multiphysics. With the optimized length of 35mm and cross-sectional area of 1.2mm2, the RTG with four thermoelectric modules achieved a 15.8mW output power under 1W heat source power. The maximum conversion efficiency calculated using COMSOL code increased to 1.58%. According to the optimized electrical output, the micro-radial RTG is expected to be a reliable space power supply for micro components and could satisfy the low power requirements of space missions.

Net thermoelectric power generation improvement through heat transfer optimization

Thermoelectric generation contributes to obtain a more sustainable energetic system giving its potential to harvest waste heat and convert it into electric power. In the present study a computational optimal net generation of 108.05MWh/year was produced out of the flue gases of a real tile furnace located in Spain (the equivalent to supply the energy to 31 Spanish dwellings). This maximum generation has been obtained through the optimization of the hot and cold heat exchangers, the number of thermoelectric modules (TEMs) installed and the mass flows of the refrigerants, including the temperature loss of the flue gases and the influence of the heat power to dissipate over the heat dissipators.The results are conclusive, the installation of more TEMs does not always imply higher thermoelectric generation, so the occupancy ratio (δ) has to be optimized. The optimal generation has been achieved covering the 42% of the surface of the chimney of the tile furnace with TEMs and using heat pipes on the cold side, which present smaller thermal resistances than the finned dissipators for similar consumptions of their fans. Moreover, the high influence of the consumption of the auxiliary equipment shows the importance of considering it to obtain realistic usable electric energy from real applications.

The optimization design and parametric study of thermoelectric radiant cooling and heating panel

Thermoelectric radiant air-conditioning (TE-RAC) system is a promising approach to implement thermoelectric technology in large-scale refrigeration system applications in future. However, no standard exists for the in situ design and the performance evaluation of thermoelectric radiant heating/cooling panel. Thus, this study aims to not only clarify the design procedure but also to share our thermal physical model and design configurations of the thermoelectric radiant panel to serve as a reference for other similar design cases. In addition, a simplified representation approach for the thermal characterization of thermoelectric panels is also discussed. The main design variables are the number of thermoelectric modules and the size of radiant panels. The inner surface transient temperature distribution of thermoelectric radiant panels is discussed, and the approaches for improving the uniformity of the inner surface temperature are proposed. The influence of cooling/heating load on the uniformity of the inner surface temperature is a slight larger than the size of the panel, so the matching design is very important. The results show that the optimal thickness of thermoelectric radiant panels is 4mm, and the number of thermoelectric modules (TEM) is 16 per square meter, which also could solve the issues about dew formation and uniformity of inner surface temperature.

Effect of Thermoelectric Modules’ Topological Connection on Automotive Exhaust Heat Recovery System

In automotive exhaust-based thermoelectric generators (AETEGs), a certain number of thermoelectric modules are connected in series and/or parallel to recover energy from exhaust gas, which provides a way to improve fuel efficiency of the vehicle. Because of the temperature distribution on the surfaces of heat exchanger, several types of modules are planned for use in an AETEG; however, property disparities among modules exist and wire resistance cannot be neglected in practical application, so experiments have been carried out to research effects of the two factors on the maximum output power of series and parallel connection. The performance of series and parallel connections have been characterized, and mathematic models have been built to analyze and predict the performance of each connection. Experiments and theoretical analysis reveal that parallel connection shows a better performance than series connection when large differences of Seebeck coefficient and resistivity exist. However, wire resistance will cause more significant power dissipation in parallel connection. The authors believe the research presented in this paper is the first to carry out an examination of the impact of module property disparity and wire resistance on the output power of an array of thermoelectric modules connected in series and parallel, which provides a reference for choosing module connection in AETEGs.

Experimental analysis with numerical comparison for different thermoelectric generators configurations

Thermoelectric (TE) energy harvesting is a promising perspective to use waste heat. Due to the low efficiency of thermoelectric materials many analytical and numerical optimization studies have been developed. To be validated, an optimization must necessarily be linked to the experience. There are a lot of results on thermoelectric generators (TEG) based on experiments or model validations. Nevertheless, the validated models concern most of the time one TE module but rarely an entire system. Moreover, these models of complete system mainly concern the optimization of fluid flow rates or of heat exchangers. Our choice is to optimize the number of these modules in a whole system point of view. A numerical model using a software for numerical computation, based on multi-physics equations such as heat transfer, fluid mechanics and thermoelectricity was developed to predict both thermal and electrical powers of TEG. This paper aims to present the experimental validation of this model and shows interesting experimental results on the location of the TE modules. In parallel, an experimental set-up was built to compare and validate this model. This set-up is composed of a thermal loop with a hot gas source, a cold fluid, a hot fin exchanger, a cold tubular exchanger and thermoelectric modules. The number and the place of these modules can be changed to study different configurations. A specific maximum power point tracker DC/DC converter charging a battery is added in order to study the electrical power produced by the TEG. The analysis of the influence of the number of thermoelectric modules and influence of electric currents on the produced electrical power was investigated. Different operating points of hot inlet gas airflow rate and of cold inlet source temperature were tested. Both experimental and numerical results show the necessity to optimize the position, the number of TE modules and the electrical currents.

Structure and Output Characteristics of a TEM Array Fitted to a Fin Heat Exchanger

In the design of a thermoelectric generator, both the heat transfer area and the number of thermoelectric modules (TEMs) should be increased accordingly as the generator power increases; crucially, both aspects need to be coordinated. A kilowatt thermoelectric generator with a fin heat exchanger is proposed for use in a constant-speed diesel generator unit. Interior fins enhance convective heat transfer, whereas an exterior fin segment increases the heat transfer area. The heat transfer surface is double that of a plane heat exchanger, and the temperature field over the exterior fins is constrained to a one-dimensional distribution. Between adjoining exterior fins, there is a cooling water channel with trapezoid cross-section, enabling compact TEMs and cooling them. Hence, more TEMs are built as a series–parallel array of TEMs with lower resistance and more stable output current. Under nonuniform conditions, to prevent circulation and energy loss, bypass diodes and antidiodes are added. Experiments and numerical calculations show that, with matching and optimization of the heat exchanger and TEM array, a stable maximum output power is obtainable from the interior of the thermoelectric generator system, which can be connected to an external maximum power point tracking system.

Optimal Arrangement of Thermoelectric Modules for Recovering the Waste Heat of Damavand Power Plant using Mutable Smart Bee and Neuro-Fuzzy System

In current research, the authors intend to find the optimal arrangement of planar thermoelectric modules to maximize the generated electricity and minimize the maintenance cost of a power system called Damavand power plant. Optimal arrangement is done by mounting a number of thermoelectric modules within the condenser in order to recover the waste heat of the thermal system. For this purpose, firstly, an adaptive neuro fuzzy inference system (ANFIS) is utilized to model the generated power of thermoelectric module and the corresponding maintenance cost. Thereafter, Gambit and Fluent softwares are applied to evaluate the temperature rate through the length of thermoelectric component. Given the derived information, the authors use a recent spotlighted metaheuristic called mutable smart bee algorithm (MSBA) to optimally arrange the thermoelectric modulus for recovering the waste heat of Damavand power plant. Based on the obtained numerical results, it is proven that the proposed frame work is completely capable of finding a practical arrangement of thermoelectric cells within the entry of condenser component.

Thermoelectric energy harvester: Design considerations for a bearing node

This article presents fundamental design considerations of the thermoelectric harvester to be used in applications for machine condition monitoring or condition-based maintenance. The power to be harvested is the thermal power loss of the bearing. The aim of the harvester is to maintain the energy neutral operation. By the numerical analysis of the system equivalent model, the pulse width of the associated sensor active state is analyzed together with the power capacity of the harvester and its operation cycle length. The article contains an analysis of the influence of design parameters onto the system performance. The assumed design variables are thermal resistances of the heat sink, insulating partition, and the number of thermoelectric modules. The electrical circuitry is described by the energy buffer capacitance, sensor active state duration, and equivalent resistance of the adjoined circuitry during the passive and active states. The continuous and burst modes of operation are taken into consideration. The preliminary experimental proof of the concept is presented as well.

Heat Transfer Model for Blade Twist Actuator System

DOI: 10.2514/1.23120 A lumped mass heat transfer model is developed for a blade twist actuator system that uses thermally activated shape memory alloys to alter the shape of a wing. These alloys are coupled with thermoelectric modules that supply the heat necessary to activate the shape alteration characteristics of the material. The model predicts the unsteady temperatures in different portions of the actuator system, and comparisons between experimental data and the heat transfer model are made. Furthermore, parametric studies are made of system variables to optimize the numerical model, and the effect of each variable on the comparison is examined. Differences between the numerical and experimental models are discussed, and efforts are made to minimize this difference through variations in the numerical variables. The potential for using this technology to increase range and payload of aircraft is discussed. Nomenclature cp = specific heat, J=kg K h = convective heat transfer coefficient, W=K I = electrical current, A N = number of thermoelectric modules in row n = number of time steps q = heat flow, W R = electrical resistance, � T = temperature of thermal zone or atmosphere, C t = time, s � = Peltier coefficient, V=K � t = time step, s � = thermal conductivity, W=K