Experimental study of a domestic thermoelectric cogeneration system

Thermoelectric application for power generation does not appear to be appealing due to the low conversion efficiency given by the current commercially available thermoelectric module. This drawback inhibits its wide application because of the overall low thermal efficiency delivered by typical thermoelectric applications. This paper presents an innovative domestic thermoelectric cogeneration system (TCS) which overcomes this barrier by using available heat sources in domestic environment to generate electricity and produce preheated water for home use. This system design integrates the thermoelectric cogeneration to the existing domestic boiler using a thermal cycle and enables the system to utilise the unconverted heat, which represents over 95% of the total absorbed heat, to preheat feed water for domestic boiler. The experimental study, based on a model scale prototype which consists of oriented designs of heat exchangers and system construction configurations. An introduction to the design and performance of heat exchangers has been given. A theoretical modelling for analysing the system performance has been established for a good understanding of the system performance at both the practical and theoretical level. Insight has also been shed onto the measurements of the parameters that characterise the system performance under steady heat input. Finally, the system performance including electric performance, thermal energy performance, hydraulic performance and dynamic thermal response are introduced.     

Experiments and simulations on low-temperature waste heat harvesting system by thermoelectric power generators

In this case study, a system to recover waste heat comprised 24 thermoelectric generators (TEG) to convert heat from the exhaust pipe of an automobile to electrical energy has been constructed. Simulations and experiments for the thermoelectric module in this system are undertaken to assess the feasibility of these applications. A slopping block is designed on the basis of simulation results to uniform the interior thermal field that improves the performance of TEG modules. Besides simulations, the system is designed and assembled. Measurements followed the connection of the system to the middle of an exhaust pipe. Open circuit voltage and maximum power output of the system are characterized as a function of temperature difference. Through these simulations and experiments, the power generated with a commercial TEG module is presented. Overview this case study and our previous work, the results establish the fundamental development of low-temperature waste heat thermoelectric generator system that enhances the TEG efficiency for vehicles.     

Analytical procedure to obtain internal parameters from performance curves of commercial thermoelectric modules

Manufacturers of commercial thermoelectric modules provide datasheets of the modules including information and graphs about the performance attained at several working conditions. Details about internal parameters are not made available to customers, because in the broad majority of the cases they are not necessary. However, when developing non-standard applications or conducting research projects it is sometimes necessary to make the modules work in different conditions than those shown in the performance curves. This paper shows a methodology to extract thermoelectric internal parameters from the information provided by performance curves, hence allowing scientists to predict the performance of the module at any working condition. The method is based on the basic equations that link thermal and electrical dynamics in which some parameters must be estimated. As a result it is possible to predict the behavior of the modules if they are operated in a non-standard way. One good example is to simulate how a module designed for cooling applications will behave if used as a Seebeck module for power generation. The proposed methodology has been successfully applied to a commercial Peltier module for which the behavior as a thermoelectric generator was simulated and then tested experimentally, attaining very similar results.     

Design optimization of thermoelectric devices for solar power generation

We present an improved theoretical model of a thermoelectric device which has been developed for geometrical optimization of the thermoelectric element legs and prediction of the performance of an optimum device in power generation mode. In contrast to the currently available methods, this model takes into account the effect of all the parameters contributing to the heat transfer process associated with the thermoelectric device.The model is used for a comparative evaluation of four thermoelectric modules. One of these is commercially available and the others are assumed to have an optimum geometry but with different design parameters (thermal and electrical contact layer properties).Results from the model are compared with experimental data of the commercial thermoelectric module in power generation mode with temperature gradient consistent with those achievable from a solar concentrator system. These show that it is important to have devices optimized specifically for generation, and to improve the contact layer of the thermoelements accordingly.     

Development of a thermoelectric self-powered residential heating system

Self-powered heating equipment has the potential for high overall energy efficiency and can provide an effective means of providing on site power and energy security in residential homes. It is also attractive for remote communities where connection to the grid is not cost effective. Self-powered residential heating systems operate entirely on fuel combustion and do not need externally generated electricity. Excess power can be provided for other electrical loads. To realize this concept, one must develop a reliable and low maintenance means of generating electricity and integrate it into fuel-fired heating equipment. In the present work, a self-powered residential heating system was developed using thermoelectric power generation technology. A thermoelectric module with a power generation capacity of 550 W was integrated into a fuel-fired furnace. The thermoelectric module has a radial configuration that fits well with the heating equipment. The electricity generated is adequate to power all electrical components for a residential central heating system. The performance of the thermoelectric module was examined under various operating conditions. The effects of heat transfer conditions were studied in order to maximize electric power output. A mathematical model was established and used to look into the influence of heat transfer coefficients and other parameters on electric power output and efficiency.     

Experimental investigation on controlled cooling by coupling of thermoelectric and an air impinging jet for CPU

In this study, experimental tests have been carried out on the coupling thermoelectric cooling module with minichannel heatsink subjected to impinging airflow for cooling desktop central processing unit (CPU). A controlled thermoelectric-forced test system was designed for this purpose. This was designed using electronic Arduino card. The proposed hybrid cooling system was compared with the conventional forced air-cooling technique. Three power of heat source (CPU) were adopted, investigated, and compared, namely 60, 87, and 95 W. Performance of controlled thermoelectric cooling with three preset temperature were experimentally examined. The effects of air velocity and thermoelectric input current on the case temperature (T_case), thermal resistance, and heat transfer coefficient were analyzed. Results showed that the T_case increases with the increase of its input power. In addition, increasing air jet velocity and thermoelectric input current improve CPU cooling significantly. For a CPU power of 95 W, the recorded T_case temperature was 57°C with the conventional system. While it was maintained below 50°C in the hybrid system. The thermoelectric cooler has had a major effect on CPU cooling, having 15% improvement over conventional forced air-cooling. However, this was accompanied by an increase in energy consumption in the range of 45 W.     

Dynamic test strategy for diagnosing a heat pipe cooling module

This article experimentally develops a dynamic test strategy for efficiently diagnosing a heat pipe cooling module in order to improve the time-consuming conventional steady-state test. The first step is to investigate the performance of a heat pipe by measuring its thermal resistance, and the next step is to examine the influence of the parameters on the temperature response of the heat pipe cooling module. The experimental parameters include the press force, preheating temperature, heating power, and starting time of the fan. The results show that the thermal performance of a heat pipe, the contact condition between the heat pipe and the base plate, and the heat dissipation ability of a heat sink, are diagnosed within 30 seconds. During the dynamic test, both the startup and the ability to reach uniformity of temperature of the heat pipe can be observed. In addition, the temperature response of a heat pipe cooling module based on a lumped model matches the experimental data.     

基于太阳能光伏热利用的光伏/热电(PV/TV)建筑一体化试验研究

将太阳能电池板、集热器、热电发电片结合起来,设计并制成了一套光伏/热电(PV/TV)系统,在利用太阳能电池发电的同时,收集热量并利用其发电。在北京地区进行了该系统的室外模拟试验,测试并讨论了该系统在不同结构和不同环境下的性能,探讨该系统在光伏建筑中的应用。试验结果表明,与单纯的光伏发电系统或太阳能热水系统相比,PV/TV系统具有占地面积小、综合效率高等优点。     

Development and experimental validation of a computational model in order to simulate ice cube production in a thermoelectric ice-maker

We have developed a computational model which allows the simulation of a thermoelectric device to make ice cubes in a vapour compression domestic fridge. This model solves both the thermoelectric and heat transfer equations, including the phase change equations in the ice cube production.The inputs of the model are: the thermoelectric parameters as a function of the temperature; dimensions; material properties (thermal resistances and capacities) and the boundary conditions (room temperature and voltage supplied to the Peltier module). The outputs are the values of the temperature for all the elements of the thermoelectric ice-maker and the ice production.In the experimental phase a prototype of a thermoelectric ice-maker incorporated in a vapour compression domestic fridge was constructed in order to adjust and validate the computational model, and to optimise the experimental application. This ice-maker has two Peltier modules, some aluminum cylinders, called fingers, where the ice is made, and a component that acts as heat extender and dissipater which connects the hot side of Peltier module with the freezer compartment. The ice formation on the fingers is obtained by the cooling on the Peltier modules. When the ice cubes are formed, the voltage polarity of the thermoelectric modules is switched so the fingers warm up until the ice around the fingers melts. Then the ice cubes are dropped by gravity.This paper studies the production of ice cubes using the computational model and the experiment results and analyses the most important parameters for the optimisation of the ice-maker (voltage supplied to the Peltier module, thermal resistance of the hot side dissipater and initial water temperature).     

摩托车路试仪检定装置研究开发

摩托车制动性能检测工作是保障道路交通安全的一项重要措施.相关检测机构广泛使用摩托车路试仪作为检测摩托车制动性能的仪器,然而目前国内尚缺少对路试仪进行检定的装置.针对摩托车路试仪的检定方法进行了探讨,进而研发了一种精度高、操作简单方便、性能可靠的路试仪检定装置.该装置以MSP430F149单片机为控制核心,主要包括电源模块、转速检测模块、步进电机驱动模块、键盘及显示模块等.对该装置的总体方案、系统硬件和软件设计、系统仿真调试及样机实验等进行了阐述.对于摩托车制动性能检测领域有着重要的现实意义,研制的检定装置将具有广阔的应用前景.     

Development and testing of a domestic woodstove thermoelectric generator with natural convection cooling

A thermoelectric generator was fitted to the side of a domestic woodstove. The generator was driven using one or more thermoelectric modules designed to give significant power at a reasonable cost. The thermoelectric generator was air cooled by natural convection using a commercially available heat sink. Testing was undertaken under a controlled woodstove firing rate and temperatures, and open circuit voltages were monitored over extended periods. The maximum steady state matched load power was 4.2 W using a single module. The use of multiple modules with a single heat sink was found to reduce the total power output relative to the single module case as a result of reduced hot to cold surface temperature differences.     

A mathematic model of thermoelectric module with applications on waste heat recovery from automobile engine

Over two-thirds energy of fuel consumed by an automobile is discharged to the surroundings as waste heat. The fuel usage can be more efficient if thermoelectric generators (TEG) are used to convert heat energy into electricity. In this study, a thermoelectric module composed of thermoelectric generators and a cooling system is developed to improve the efficiency of an IC engine. Two potential positions on an automobile are chosen to apply this module, e.g. exhaust pipe and radiator to examine the feasibility. To predict the behaviors of this module, a one dimensional thermal resistance model is also build, and the results are verified with experiments.     

Computational model for refrigerators based on Peltier effect application

A computational model, which simulates thermal and electric performance of thermoelectric refrigerators, has been developed. This model solves the non-linear system that is made up of the thermoelectric equations and the heat conduction equations providing values for temperature, electric consumption, heat flow and coefficient of performance of the refrigerator. Finite differences method is used in order to solve the system and also semi empirical expressions for convection coefficients.Subsequently a thermoelectric refrigerator with an inner volume of 55 × 10⁻³ m³ has been designed and tested, whose cold system is composed of a Peltier pellet (50 W of maximum power) and a fan of 2 W. An experimental analysis of its performance in different conditions has been carried out with this prototype, which, in his turn, has been useful for assessing the accuracy of the developed model. The built thermoelectric refrigerator prototype, offers advantages with respect to vapour compression classical technology such as: a more ecological system, more silent and robust and more precise in the control of temperatures which make it suitable for camping vehicles, buses, special transports for electro medicine, etc.     

The design and development of an HT-PEMFC test cell and test station

A proper system must be applied in order to have reliable power production and higher levels of durability. The functions of this system are to fully utilize the benefits of the fuel cell components and to deliver the required power. This paper presents the design for an HT-PEMFC single-cell test cell with the development of a test station to operate the cell. The single-cell test cell and the real-time monitoring test station were designed using LabVIEW software, and were implemented using NI's cFP hardware devices, the details of which are provided. The architecture of the test station was aimed at measuring and controlling the mass flow rate, pressure and temperature of the reactant gases, and the stack temperature and current. An electronic load, with a quick dynamic response, was used to test the fuel cell reaction. The start-up, shutdown and monitoring functions were managed by the test station, which monitored the critical parameters of the fuel cell, namely, the voltage, current loading, generated power, hydrogen/air inlet and outlet and stack temperature. The results showed that the designed and developed single-cell HT-PEMFC and test station were able to generate power. An in-depth research needs to be conducted into the innovative design and development of HT-PEMFC systems since these are the key factors for optimum performance.     

Sensitivity analysis of the effects of the thermal parameters of exhaust gases on the output of a thermoelectric generator

Recovering the dissipated heat from exhaust is a useful means of reducing the energy consumption level as well as cutting down on environmental pollution. An efficient technique for recovering this lost heat is the use of thermoelectric generators, which directly convert the dissipated heat into useful electrical energy. In this paper, a whole thermoelectric generator system installed on the exhaust pipe of a vehicle has been modeled, and the effects of thermal parameters on the output of this thermoelectric generator have been measured and evaluated by means of sensitivity analysis. The E‐Fast sensitivity analysis method has been used in this study. The sensitivity analysis results indicate that, among the thermal parameters examined, the temperature of gases entering the heat sink installed at exhaust pipe outlet () has the greatest influence (37%) and the flow rate of fluid entering the heatsink installed on the cold side of thermoelectric modules () has the second greatest influence (17%) on the output power of the considered thermoelectric generator. By using these results, the best cases of hot exhaust gases from various industries and vehicles with the highest potential of recovering the dissipated energy and heat from them by thermoelectric generators can be identified.     

重型燃气轮机燃烧室设计与试验研究

完成了用于110MW级重型燃气轮机的干低排放燃烧室的设计和第一阶段试验验证。燃烧室采用轴向分级的贫油预混燃烧技术降低NOx排放,将火焰筒头部分为环形区、预混区和扩散区三个燃烧区。单管燃烧室全尺寸中压试验结果表明：在第一种工作模式下,燃烧室的总压损失、起动点火、燃烧效率、出口温度分布、压力脉动和火焰简壁温均满足设计要求,但NOx排放超过设计要求。受周期和试验条件限制,第二种工作模式下的NOx排放试验尚未完成。     

Parametrical analysis of the design and performance of a solar heat pipe thermoelectric generator unit

This paper describes a solar heat pipe thermoelectric generator (SHP-TEG) unit comprising an evacuated double-skin glass tube, a finned heat pipe and a TEG module. The system takes the advantage of heat pipe to convert the absorbed solar irradiation to a high heat flux to meet the TEG operating requirement. An analytical model of the SHP-TEG unit is presented for the condition of constant solar irradiation, which may lead to different performance characteristics and optimal design parameters compared with the condition of constant temperature difference usually dealt with in other studies. The analytical model presents the complex influence of basic parameters such as solar irradiation, cooling water temperature, thermoelement length and cross-section area and number of thermoelements, etc. on the maximum power output and conversion efficiency of the SHP-TEG. Simulation based on the analytical model has been carried out to study the performance and design optimization of the SHP-TEG.     

Experimental and analytical study on thermoelectric self cooling of devices

This paper presents and studies the novel concept of thermoelectric self cooling, which can be introduced as the cooling and temperature control of a device using thermoelectric technology without electricity consumption.For this study, it is designed a device endowed with an internal heat source. Subsequently, a commonly used cooling system is attached to the device and the thermal performance is statistically assessed. Afterwards, it is developed and studied a thermoelectric self cooling system appropriate for the device.Experimental and analytical results show that the thermal resistance between the heat source and the environment reduced by 25-30% when the thermoelectric self cooling system is installed, and indicates the promising applicability of this technology to devices that generate large amounts of heat, such as electrical power converters, transformers and control systems. Likewise, it was statistically proved that the thermoelectric self cooling system leads to significant reductions in the temperature difference between the heat source and the environment, and, what is more, this reduction increases as the heat flow generated by the heat source increases, which makes evident the fact that thermoelectric self cooling systems work as temperature controllers.     

双机并车试验台高速采样系统关键技术研究

采用高速数据采集卡实现了对柴油机转速、燃油齿条位移及柴油机输出扭矩等重要参数的实时高速采集和存储;并设计了采集数据滤波、动态波形显示及分析程序;提出了转速采集及分析的新方法。实际配机使用表明:系统运行正常,参数采样信号稳定;可为研究柴油机并车过程中的参数监测及控制起到良好的辅助作用。