基于TED原理的燃气灶发电模型及数值模拟

为了提高资源的有效利用率,对燃气灶等设备进行废热回收,提出一种温差发电模型。运用FLUENT软件对该发电装置的温度场、流场进行了三维仿真计算。研究热端设置成格栅结构、热端与水平面的倾斜角大小对余热回收效率的影响。结果表明:将热端设计成格栅结构可以有效提高其辐射温度,改变热端与水平面的倾斜角可以将冷热端温差最高提升57%,进而可以提高温差发电装置的热效率。     

计及电热耦合的多级温差发电建模和试验研究

为准确描述多级温差发电器实际工作时各级节点温度分布与通过热功率及其热电输出特性之间的关系,文章建立了计及电热耦合的多级温差发电数值分析模型。运用贪心算法(Greedy Algorithm)编程求解,以常见的Bi2Te3,PbTe和SiGe 3种半导体材料的发电片为例,通过试验验证了模型的正确性,并进一步研究了电热耦合效应对多级温差发电器的Seebeck电压、发电功率和热电转换效率的影响。模型的数值求解和实测结果对比表明:由于电热耦合效应的存在,多级温差发电器在实际工作时各级节点的温度上升,但冷、热端的温差值减小;电热耦合效应会使Seebeck电压、发电功率和热电转换效率明显降低,下降幅度随多级温差发电器热端温度的升高而增大,随发电器级数的增加而减小。     

发动机温差发电仿真系统研究

构建了车用发动机温差发电系统的数字仿真系统,仿真流程是：根据发动机的结构,采用AVL—BOOST软件对发动机的运行工况进行仿真,以获得的排气温度、压力、流速值作为温差发电计算的初始条件;建立温差发电器的几何模型,采用Star—CD软件对它的传热特性进行数值计算,获得转换元件的温度分布,进而可以计算得到温差电源的输出参数。文中针对某型号四冲程汽油机一内置式温差发电器系统,给出了计算实例。     

ZT值温度依存性对温差发电器热电性能的影响

为了评估热电材料ZT值温度依存性对热电发电器性能的影响,基于HZ-20商用热电材料的热物性参数,分别采用定物性与变物性的计算方法,对温差发电器在具有不同热源温度下的工作性能进行理论研究。研究结果表明,当采用定物性方法计算时(即不考虑ZT值温度依存性),输出功率及相应转换效率的计算值都较采用变物性计算时存在一定的偏差。当半导体热端温度低于定物性计算时采用的定性温度值时,偏差很小,但随着半导体热端温度的继续增加,偏差则越来越大,高热端温度下计算得到的计算偏差达30%左右。因此,热电材料ZT值温度依存性对温差发电器热电性能的影响不容忽视。     

应用温差发电器降低锅炉排烟热损失

锅炉是一种特殊结构部件，既可以为热电效应为基础的温差发电器提供热源，也可以为其提供冷源，这为应用温差发电器创造了条件。应用温差发电器可以降低排烟温度，减少排烟热损失。文章对应用温差发电器的可能性以及应用后的效率进行了分析，结论是可以提高锅炉效率；提出了如何应用温差发电器件的方法．并对锅炉应用温差发电器降低排烟损失应该考虑的问题进行了分析。     

相变传热在半导体热电转换中的应用

为了解决温差发电技术中发电片热端与尾气间热损失大造成输出功率和热电转化效率不高的问题,提出在尾气与温差发电片热端加装相变传热结构,并计算了加装相变结构后发电器的输出功率和效率,同时与相同传热面积时无相变传热情况进行了对比,并模拟了蒸发段管数和冷凝段高度对发电器输出功率及效率的影响。结果表明,相变结构可提高发电器的输出功率及转化效率,且输出功率随冷凝段长度增加出现峰值,蒸发段管数越多,峰值对应的冷凝段长度越长,而发电效率则随冷凝段长度增加而减少;蒸发段管数增加,输出功率和发电效率均增大。     

温差发电技术及其在汽车发动机排气余热利用中的应用

介绍了采用半导体热电元件的温差发电技术的特征，包括对半导体材料的要求，适合作汽车排气余热发电的温差发电器的结构等，给出了美、日等国车用温差发电器的实例，还对相关技术的发展趋势作了分析。     

小型温差发电器性能影响因素研究

通过实验的方式测量了热空气流量、温度和冷却风速对半导体温差发电器性能的影响。研究结果表明:随着热空气流量的增加,热端换热效果增强,使得集热器温度升高,进而冷热源温差增大,热电模块的开路电压增加。随着热空气温度的升高,集热器的温度同时也在升高,此时冷热源温差增大,热电模块的开路电压增加。随着冷却风风速的增加,冷端换热器的换热效果增强同时也影响热端集热器的温度。     

一种新型汽车尾气多通道热能发电系统

根据温差发电原理,设计了一种新型网格状通气管式的温差发电装置,实现对汽车尾气热能的再利用。通过优化温差发电装置的结构,改变了水箱结构,增加了废热通道数量,能够贴更多的温差发电片,从而提高转换效率。通过UG(计算机辅助设计软件)建立汽车尾气温差发电装置的理论模型,经过计算,当温差等于100℃时该装置的转换效率约等于5.67%。与其他温差发电装置进行比较,热油式温差发电器在260℃温差下最大热能转换效率可达4.389%,而汽车尾气温差发电器输出功率随着烟气温度的升高近似成线性递增,热能转换效率较低[1],通过比较得出,本装置不仅提高了转换效率,且达到相同转换效率时所对应的温差值也相应减少。     

翅-管型温差发电器的机-热耦合仿真设计

为了提高内燃机排气余热能量的利用率,设计了一种千瓦级的翅-管型温差发电器,该装置具有结构紧凑和机械预紧力小的特点。按照正交实验的排序,对机体进行机-热耦合仿真,分析结构参数对于温度分布的影响,以及夹角-弹簧机构对于压紧力的影响,得到了优化方案和弹簧刚度值,满足了温差发电元件对于额定温度和压紧力的要求。     

高温温差发电装置集热器结构数值仿真研究

设计了一种针对高温烟气的圆筒式温差发电装置,在装置中设置分流桶增强烟气侧的换热效果。利用Ansys Fluent软件对装置的温度场、速度场及排气压降进行仿真模拟,分析了不同分流桶的桶直径、端盖孔直径和分流孔直径对热电模块冷热端温度分布的影响。仿真结果表明：温差发电系统集热器通道中设置分流桶可以实现高效温差发电,分流桶端盖未开孔时装置的换热效果优于端盖开孔结构;适当减小分流孔直径或增大分流桶直径会提升热电模块的冷热端温差,分流孔直径为2 mm时的换热效果最优,分流桶直径过大会使热电模块温度分布及温差的均匀性降低;系统烟气压降会随着分流孔直径的增大或分流桶直径的减小而降低。     

Power generation characteristics of a sandwich‐type self‐heating thermoelectric generator with spatially varying embedded heat source

Power generation characteristics of a sandwich‐type thermoelectric generator in which the heat source is embedded into thermoelectric elements are investigated. Our previous work on a similar concept only considered a uniform heat source distribution inside thermoelectric elements. In this work, the effect of the spatial distribution of a heat source is examined. In particular, the effect of the concentration of heat source near the one end, that is, the hot end, is intensively studied as a potential means of improving the efficiency of the device. Although the effects of heat source concentration in impractical cases without heat transfer limitations on the cold side remain ambiguous, it become clear that heat source concentration indeed has positive effects in more realistic cases with finite heat transfer coefficients imposed on the cold side. Because of the relatively low efficiency of typical thermoelectric generation, a significant amount of heat must be dissipated from the cold end of the thermoelectric element. Greater heat source concentration near the hot end leads to more effective utilization of available heat source, reduces the amount of heat rejected at the cold end, and lowers the hot end temperature of the thermoelectric element. Overall, it is suggested that heat source concentration can be used as a method to achieve more efficient operation and better structural integrity of the system. Copyright © 2015 John Wiley & Sons, Ltd.     

Electric power generation from solar pond using combined thermosyphon and thermoelectric modules

Salinity-gradient solar ponds can collect and store solar heat at temperatures up to 80 °C. As a result, these water bodies act as a renewable source of low grade heat which can be utilized for heating and power generation applications. In this paper, design and test result of the combined system of thermosyphon and thermoelectric modules (TTMs) for the generation of electricity from low grade thermal sources like solar pond is discussed. In solar ponds, temperature difference in the range 40-60 °C is available between the lower convective zone (LCZ) and the upper convective zone (UCZ) which can be applied across the hot and cold surfaces of the thermoelectric modules to make it work as a power generator. The designed system utilizes gravity assisted thermosyphon to transfer heat from the hot bottom to the cold top of the solar pond. Thermoelectric cells (TECs) are attached to the top end of the thermosyphon which lies in the UCZ thereby maintaining differential temperature across them. A laboratory scale model based on the proposed combination of thermosyphon and thermoelectric cells was fabricated and tested under the temperature differences that exist in the solar ponds. Result outcomes from the TTM prototype have indicated significant prospects of such system for power generation from low grade heat sources particularly for remote area power supply. A potential advantage of such a system is its ability to continue to provide useful power output at night time or on cloudy days because of the thermal storage capability of the solar pond.     

冷、热端温度对半导体热电堆发电性能影响的初步研究

对半导体热电堆的发电性能进行了实验研究,得出这种半导体热电堆在冷端温度不变的情况下,其发电性能与热端温度的关系,以及半导体热电堆在热端温度的情况下,冷端温度对其发电性能的影响,发现半导体热电堆作为电源时,其内阻对它的性能指标有很大的影响,而且内阻随着温度的升高而增大,采用间化的方法从理论上计算了热电堆的特性,得到了计算与实验结果基本吻合。     

高效分段温差电单偶仿真设计

由于温差电材料的热电性能随着温度变化而变化,优值系数ZT也随之改变,导致不同温差电材料的只在某一温度区间有较高的效率,因此,分段温差电元件概念被提出,据此可以在很大程度上提高热电转换效率。本文建立了基于P型BiSbTe＼Zn4Sb3＼CeFe4Sb12、N型Bi2Te3＼GoSh3半导体分段温差电单偶模型异进行了ANSYS有限元分析。在对分段温差电元件长度比、截面比及负载电阻均进行优化后,得到在冷端温度为298K,热端温度为973K、873K、773K、673K时的理论转换效率分别为15．2％、13．8％、12．1％、10．6％。     

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.     

基于改进贪心算法的温差电器件电-热耦合效应研究

温差电器件实际工作时由于内电阻的存在不可避免地会产生焦耳热,传统的温差电研究中虽注意到温差发电过程中的焦耳热现象,但只是在等效计算热功率时消去焦耳热部分,而忽略了焦耳热对温差电器件热、冷端温度分布的影响。针对传统研究的不足,考虑实际应用中的电-热耦合效应,运用理论推导的方法建立了第三类边界条件下的温差发电负载模型,并利用改进贪心算法迭代求解,最后以SP1848-21745型温差发电片为例,通过试验验证了模型与算法的正确性。模型的数值求解与发电片实测结果对比表明,考虑了电-热耦合效应的温差发电负载模型的热电输出值更接近实测值。     

Study of the influence of heat exchangers' thermal resistances on a thermoelectric generation system

In this paper, a computational study of the influence of the heat exchangers' thermal resistances (in both the hot and cold side) on the efficiency of a thermoelectric generation device has been carried out.