Thermo-electric generators

Where a.c. supplies do not exist, other sources of power can be used such as d.c. generators, and either diesel or gas driven. Alternatively, thermoelectric generators may be considered if the power requirement is relatively low. Thermo-electric generators are available in relatively small outputs only as shown in Table 10.28. They have the advantage of being completely self-contained since they are powered by taking off some of the gas which passes through the pipeline. 

In the current CHTR design, direct thermo-electric conversion devices are assumed to produce electricity. A cascaded system made of an array of Si-Ge or TAGS (Ti/Ag/Ge/Si), or Pb-Te based thermo-electric generators is being designed for this purpose. 

The fact of being able to feed MCFCs easily with natural gas, and their high operating temperature, naturally orient their use toward stationary applications. Co-generation may consist of exploiting the heat produced either to heat buildings or indeed to drive a thermo-electrical generator. 

Fig. 18. (a) Ultrafast electron diffraction apparatus consisting of an electron gun chamber, a diffraction chamber, and a detector chamber. Two fs laser pulses are used, one to initiate the chemical change and the second to generate the electron pulse, (b) Detector system incident electrons either directly bombard a small CCD or strike a phosphor-coated fused fiber-optic window. Light emitted from the phosphor is amplified by an image intensifies and brought to a scientific-grade CCD. Both CCDs are thermo-electrically cooled [reproduced with permission from (96), p. 1601. 

The SCOR is mainly developed for electricity generation, providing competitive costs compared with large sized reactors through system simplification and compactness in plant layout. However, the SCOR may be used in cogeneration schemes like seawater desalination using low temperature processes, such as thermo-compression or multi-effect distillation. 

Thermo-electric properties of conductive polymer nanofibers can be interesting for energy generation. In this case, a temperature gradient across a material is exploited to generate electricity (Seebeck effect). To this aim, one of the most important performance parameters is the dimensionless figure of merit ... 

Electrical power was utilized in Italy during the 1890s. For this purpose a trust was formed by the German Siemens Company, which included the Edison company and the Dynamo company, and which was financially supported by the Deutsche Bank. Power plants, mainly hydro-electric, were built in the northern regions. The power generators, both hydro- and thermo-electric, were manufactured by the Siemens firm. In the first years of the twentieth century Edison electrical bulbs lit Italian... 

Figure 2.1 Generation of thermo-electromotive force in a closed electric circuit made of two different metals 7 and 2. T and T2 are the junction temperatures.

A Study of In-plant Electric Power Generation in the Chemical, Petroleum Refining and Paper and Pulp Industries," Thermo Electron Corporation Report No. TE5429-97-76. 

An alternative approach is to employ the thermal energy from the solar concentrator to generate electricity directly by means of a PV cell based on a semiconductor with a low band gap e.g., 0.6 eV) that is sensitive to infrared radiation. Such thermo-photovoltaic cells are already in small-scale specialized use by the military, although with the heat provided by a propane burner, rather than from the Sun. This is an alternative to the thermoelectric effect for converting heat to electricity. 

Figure 8.30 The Si(Li) semiconductor detector, (a) Schematic shows the n-type Si region on one end of the Si crystal, a central charge depleted intrinsic region and p-type Si on the other end. (b) The actual detector has 200 A layers of gold as electric contacts on each end of the crystal. An X-ray photon striking the intrinsic region generates electron-hole pairs within the diode. [Fig. 8.30(b) courtesy of Thermo ARL (www.thermoARL.com).]...

Figure 10.13 shows experimental setup for the optical characteristic measurement of PMNT ceramics [133]. The size of PMN-PT ceramic sample was 5 mm X 2 mm x 1 mm for length x width x thickness. Ti/Pt/Au layers were sputtered on both surfaces of the ceramics as electrodes. Two collimators were used to collimate the incident beam and receive the transmission beam. The output beam was detected by using an optical spectrometer and phase demodulation. Because the PMN-PT electro-optic ceramics have a large refractive index, i.e., n = 2.465, the ceramic samples could be considered as a Fabry-Perot (FP) resonator, which can be used to measure the electric hysteresis and thermo-optic coefficient. The applied voltage generated a transverse electro-optic effect for the transmission light beam. 

Two typologies of heat recovery are generally possible thermal and electric cogeneration is also a third, mixed opportunity. Since thermal heat recovery strictly depends on the use of heat, the thermo-dynamic rdated to it must be adapted and a general discussion cannot be easUy applied. Some parameters discussed here can also be useful for a discussion on thermal heat recovery. The increasing cost of electricity as well as often available government incentives drives increased focus on heat recovery with the aim of power generation. 

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