The device presented in Figure 6 is composed of thermoelectric modules (A) that enable primarily heat trans- fer from or to the temperature-controllable surface of a mould cavity (B). The secondary heat transfer is enabled via cooling channels (C) that deliver constant tempera- ture conditions inside the mould. The thermo-electric modules (A) operate as a heat pump, and as such manipu- late with the heat derived to or from the mould by the fluid- cooling system (C). The system for secondary heat ma- nipulation with cooling channels works as a heat ex- changer. To reduce the heat capacity of the controllable area thermal insulation (D) is installed between the mould cavity (F) and the mould structure plates (E).
15 Read more
The overall goal of the project was to design and develop a test stand to evaluate properties of high-temperature thermoelectric modules up to 650°C. To achieve this goal, a new testing approach was developed for quick and accurate characterization. Three preliminary setups were also built, based on techniques available in the current literature, to compare issues observed in testing. A novel guard heater arrangement was used to minimize heat losses. To determine the size of the guard heater, a thermal model was developed The test setup was validated by comparing module properties from existing steady state setup as well as measuring thermal conductivity of a reference material. Uncertainty analysis on the measurements confirmed that the setup uncertainty is well within the specifications obtained from industrial partners and laboratories manufacturing modules to be tested.
161 Read more
According to Daniel Jaiench (2009), for the most part, energy leaves automobiles unused in the form of waste heat through the exhaust pipe. The part of it could be recovered using thermoelectric modules. Although both effects always occur together, each can be used on its own with extreme precision. Depending on whether a temperature difference or an electric voltage is applied to thermoelectric materials, the respective counterpart is produced electric energy, heat or cold.
24 Read more
Abstract— Thermoelectric Modules are a useful way to extract waste energy such as exhaust heat from car engines. It works on the Seebeck effect, where an electromotive force will be generated when the junction of two dissimilar metals experience a temperature difference. The efficiency of these modules are low, but advantages of being small, lightweight and maintenance- free make it an attractive addition to applications where energy per unit weight or size is a primary factor. Among the key problems is obtaining a consistent voltage to power devices which depend on a consistent voltage more than maximum power. In applications where a higher voltage than the input voltage is needed, a boost convertor is able to reach the desired voltage at the expense of reducing current. This experiment aims to assess the performance of thermoelectric modules when connected to a boost convertor, taking into account: input and output voltage, current and power, as well as convertor efficiency against various temperature differences. The experimental test rig is using two HZ-20 thermoelectric modules connected in series to a 0.9-5V to 5V boost convertor. The hot side of the thermoelectric modules were heated through a heating block while the cold side were water cooled at room temperature through cooling blocks. The surface temperature region near the hot air inlet and outlet is measured using a temperature sensors and thermal imager. Testing showed that at a temperature difference of 71 , the input voltage and current of 1.76V and 0.76A were increased and decreased respectively to 4.17V and 0.17A. At a temperature difference of 135 , the input voltage and current of 4.09V and 0.89A were increased and decreased respectively to 5.14V and 0.66A. It was also noted that the efficiency of the boost conversion increases with temperature difference, ranging from 53% at 71 to 93% at 135 . In conclusion, the usage of a boost convertor is able to increase the input voltage, decrease the input current, and reduce the range of output voltage over a range of temperature differences. The conversion process is also more efficient when the input voltage is close to the desired output voltage.
First of all, my heartiest appreciation to my final year project supervisor, Mr. Mohamad Firdaus Bin Sukri for his guidance, advice, support which have put me in the performance of thermoelectric power generator (TEG) based Hi-Z thermoelectric modules of this project. His idea, experience and knowledge had been aspiring to me abundantly.
24 Read more
Water scarcity is one of the burning issues of today’s world. Though the water covers more than two third (about 70%) of the earth’s surface but still fresh water which can be used for drinking and carrying out every day remains scarce. So, to overcome this we need to develop a method to condense water from air. However, in highly humid areas such as places close to the water source water can be obtained by condensing water vapour present in air. Here to develop water from air we use the convergent nozzle, axial fan, thermoelectric, filter and collecting tank etc. here the air from atmosphere is sucked by air fan through filter then pass it to through nozzle, which is provided with fins. While the air passing through the nozzle at exit of nozzle we place a thermoelectric to get the reduced pressure about 1atm and temperature about 18°C i.e. below the dew point temperature at that temperature and pressure the phase change takes place from the air to water thus the condensation takes place and forms the water. The power consumption for this process is very low and the obtained water is pure to drink safely.
Figure 2(a) and (b) shows SEM micrographs of the fabricated interphase between PbTe and Ni plate, generated by sintering at 623 K, 20 MPa for 5 minutes. Figure 2(b) delineates a new phase at the PbTe/Ni interface, indicating the occurrence of a reaction between the initial counterparts. The thus-formed interphase presents no major signs of cracks or defects, similar to the PbTe side of the sample (Figure 2(a)). The average thickness of the interlayer is approximately 3 µm, and the discontinuity in the morphology is unwanted for application in a thermoelectric module. The lack of a defined barrier layer could lead to instability of the junction due to Ni diffusion into PbTe 35
26 Read more
Research on waste heat energy recovery systems of the exhaust gas in automobiles, thermoelectric modules has been actively conducted in recent years. TE modules can directly convert the heat energy to electrical energy. However, the output power characteristics of the TEG are highly nonlinear and heavily depend on the cooling system, external load, and heat source a proper power conditioning circuit and maximum power point tracking control are required.
Refrigeration can be defined as the process of extracting heat from a substance using a heat exchanger. Space cooling is the same phenomenon as refrigeration, though heat is extracted from a defined space, to ensure that the temperature in the space is maintained lower than the surroundings. Refrigeration has been required since early times. Food materials, start decomposing at higher temperatures. Preservation of food caused the commercial usage of a refrigerator. Refrigeration has been used commercially since 1900s. Traditional refrigeration and space cooling techniques have made use of the Refrigerator, Air Cooler or Air- Conditioner. The major components of a traditional refrigeration system are compressor, condenser, evaporator and throttle valve. Major drawback of these systems is that they consume large amount of electricity, are expensive and not feasible for use where electricity is not dependable. This has led to consideration of alternatives to space cooling and refrigeration. There is a huge market and demand for thermoelectric cooling, except for a few drawbacks which can be easily overcome with serious consideration. A thermoelectric module belongs to the family of semiconductors that acts as a heat pump. It works on Peltier effect to produce the required output. Peltier cooler performance is a function of atmospheric temperature, hot side of heat sink performance and cold side of heat sink performance, thermal load and electrical parameters of Peltier. This review also focuses on the use of solar energy to offer maximum usage of non-conventional energy sources to enable the use of greener technology. Thermoelectric cooling has not posed as very feasible system owing to high sensitivity to fluctuations in voltage and current. Fluctuations in case of Thermoelectric Modules make them function in reverse manner, causing flow of heat to the space meant for cooling. These drawbacks have been considered and a review of suggested methods that help to enhance performance of systems that employ thermoelectric cooling has been listed here. The concept of solar energy usage came to light after the growing energy crises in our planet. The need for sustainable fuels is higher than never before. Also cleaner and greener alternatives are encouraged to make up for the damage created by conventional fuels so far. The portability of this system helps in easy transportation. The use of solar energy as a source is a boon to a large number of people from economically backward sections. The COP and correct analysis of TEC application can be carried out using performance plots. It is important to note that thermoelectric cooler performance should depend upon atmospheric conditions.
15 Read more
In this work, a portable solar thermoelectric refrigerator unit was fabricated and tested for the cooling purpose. The refrigerator was designed based on the principle of a thermoelectric module to create a hot side and cold side. The cold side of the thermoelectric module was utilized for refrigeration purposes whereas the rejected heat from the hot side of the module was eliminated using heat sinks and fans is used for heating purpose. In order to utilize renewable energy, solar energy was integrated to power the thermoelectric module in order to drive the refrigerator. Furthermore, the solar thermoelectric refrigerator avoids any unnecessary electrical hazards and provides very environmentally friendly product. In this regard, the solar thermoelectric refrigerator does not produce chloroﬂuorocarbon [CFC], which is believed to cause depletion of the atmospheric ozone layer. In addition, there will be no vibration or noise because of the difference in the mechanics of the system. In addition the rejected heat from the solar thermoelectric refrigerator is negligible when compared to the rejected heat from conventional refrigerators. Hence, the solar thermoelectric refrigerator would be less harmful to the environment. A 0.3L of water was used as the refrigerated object in these tests. Experiment and analysis on the prototype were conducted mainly under sunny outdoor conditions. It was found that the system performance was strongly dependent on the intensity of solar insulation and the temperature difference of hot and cold sides between the thermoelectric modules. The maximum temperature difference under outdoor conditions was found to be 18.2˚C. The energy efficiency of solar thermoelectric refrigerators, based on currently available materials and technology, was still lower than its compressor counterparts. Nevertheless, a marketable solar thermoelectric refrigerator would be made with an acceptable performance through some improvements. For example, further improvement in the COP may be possible through improving module contact-resistance, thermal interfaces and heat sinks. In addition, this could be achieved by including more modules in order to cover a greater surface area of the refrigeration box.
Thermoelectric modules are solid-state heat pumps that operate on the Peltier effect A thermoelectric module consists of an array of p- and n-type semiconductor elements that are heavily doped with electrical carriers. The elements are arranged into array that is electrically connected in series but thermally connected in parallel. This array is then affixed to two ceramic substrates, one on each side of the elements (see figure below). Let's examine how the heat transfer occurs as electrons flow through one pair of p- and n- type elements (often referred to as a "couple") within the thermoelectric module.
Najafi and Woodbury  proposed simulation of PVT- TEG systems and the optimum required number of TEG modules for maximizing the output power and showed that the higher solar radiation level leads to higher output power by the TEG modules due to higher temperature differences. It has been shown that at a solar flux of 2800 W/ m2, a hybrid system containing 36 thermoelectric modules is capable of producing 145W by a photovoltaic panel and 4.4 W by thermoelectric modules. Soltani et al.  tested a photovoltaic-thermoelectric hybrid system at the different cooling conditions. Natural cooling, air forced cooling, water cooling and also nanofluid cooling is applied for enhancing heat transfer of the TEG cold plate. The tests showed that using nanofluid cooling has remarkable better results for the total power of the hybrid system comparing with the air cooling methods.
12 Read more
The glass evacuated-tube solar collectors have better thermal efficiencies at the higher temperature than the conventional flat-plate solar collectors and they are suitable for applications at the temperature of above 80 0 C. The water temperature is usually required in the range of 35 to 50 0 C for domestic hot water or space heating. Thus, an evacuated tube solar collector may be used at a higher temperature to drive a combined water heating and power generation. One attractive option is to incorporate the evacuated tube solar collectors with thermoelectric modules to produce additional electricity besides its hot water production .
11 Read more
The voltage drop for a single thermoelectric leg is too low, hundreds of microvolts. So a large number of thermoelectric legs usually get connected electrically together. These legs also are thermally connected in parallel. One side is connected to the hot plate and the other one is connected to the cold plate. The plates should be highly thermal conductive and low electrically conductive.
67 Read more
Plumbous tellurid is an intermetallic compound with a cubic crystal structure. The melting point of plumbous telluride is 922 ºC . The band-gap ratio is 0.30 eV, twice as that of bismuth telluride. It is used for thermoelectric power generation between temperatures 300-900K. Figure 6and Figure7 show the variation of electrical resistivity, the Seebeck coefficient, the thermal conductivity and the optimum value of PbTe under different mixture versus temperature.
Thermoelectric (TE) materials are considered as critical components for solid-state power generating and refrig- erating devices . However, the state-of-the-art bulk thermoelectric material is only 30% efficient as the refrigerating material when compared to the Freon- based conventional refrigerating material . Hence, their relatively low energy conversion efficiency limits the practical application of TE material as a power gen- erator and/or refrigerator. The most important issue of the thermoelectric research is to increase the efficiency of thermoelectric materials. The efficiency of TE mate- rial can be defined by dimensionless thermoelectric fig- ure of merit (ZT),
Yu Wang, Yushu Shi & Di Liu  this paper presents a mathematical model of the refrigeration system based on one-dimensional heat transfer theory, and analyses respectively the operating characteristics of thermoelectric refrigerator under the condition of maximum cooling capacity and maximum cooling efficiency. The text results show that the performance of the thermoelectric cooling system coupled with heat pipe affected by the above control parameters. The ventilation rate of the cold side increases with the increasing of operating voltage and the cooling effect will be more obviously. The application of spoiler duct is possible significantly to enhance cooling system performance.
Despite such a high anticipation and achievements, the progress in the thermoelectric materials has still been limited to those current thermoelectric materials for practical applica- tions. The commercial thermoelectric materials have a relative low ZT of 1 and the average thermoelectric generators on the market have a conversion efﬁciency of approximately 5%, as shown in Fig. 1b. As can be seen, there is a great potential to seek new materials with ZT values of 2–3 to provide the desired conversion efﬁciencies to be competitive with traditional mechanical energy conversion systems. For a typical example, a thermoelectric power conversion device with ZT¼3 operating between 773 and 303 K (room temperature) would yield 50% of the Carnot efﬁciency . Therefore, it is critical to synthesize thermoelectric materials with high ZT in order to promote the practical applications of thermoelectric materials. The major activities in thermoelectric materials have been focussed on the increase of the Seebeck coefﬁcient and the reduction of the thermal conductivity. Several key reviews have been surveyed on developments in bulk materials , nanos- cale [31–33], or bulk nanostructured thermoelectric materials [1,6,34], whilst progress in understanding the key feature of the inﬂuence of interfaces on thermoelectric performance  and theory on nanostructured thermoelectric [36,37] has also been comprehensively reviewed. Here, this review tries to highlight the signiﬁcant progress in the past several years and under- stand the enhanced thermoelectric properties of nanostructured or nanoscale materials. The organization of the review is as follows. First, we discuss the basic principles for improving thermoelectric performance along with the basic methodology. And then we highlight the current research progress and focus on addressing nanostructured thermoelectric materials with ZT over 1. Finally, we identify strategies and research directions which could lead to the next generation of nanostructured thermoelectric materials.
15 Read more
A thermoelectric module is a circuit containing thermoelectric materials that generate electricity from heat directly. A thermoelectric module consists of two dissimilar thermoelectric materials joining in their ends: an n-type (negatively charged); and a p-type (positively charged) semiconductors. A direct electric current will flow in the circuit when there is a temperature difference between the two materials. Generally, the current magnitude has a proportional relationship with the temperature difference. (i.e., the more the temperature difference, the higher the current.)
Thus, the junctions and materials must be selected so that they survive these tough mechanical and thermal conditions. Also, the module must be designed such that the two thermoelectric materials are thermally in parallel, but electrically in series. The efficiency of thermoelectric modules are greatly affected by its geometrical design.