Thermoelectric couple

The proportionality constant g includes such parameters as the number of thermoelectric couples in the pile, their thermoelectric power, and the gain of the amplification device. It is supposed, moreover, that the response of the recording line is considerably faster than the thermal lag in the calorimeter. The Tian equation may also be written therefore ... 

Fig. 22. A single thermoelectric couple is illustrated that has been configured for refrigeration or power generation. The labels p (positive) and n (negative) refer to the sign of the charge carriers in each leg (open circles correspond to holes and filled circles to electrons). Refrigeration is possible in these devices because electrons (or holes) carry heat, and hot electrons (holes) can be forced away from the cold end of the device by the battery. If a temperature difference is externally imposed on the device, useful power can be extracted.

Fig. 21.28. The multi-hundred-watt electric generator.Three units on Voyager generated 475 watts from the decay heat of plutonium-238 acting on thermoelectric couples.

The temperature was measured by twelve thermoelectric couples and was recorded by two multilogers. The places where the temperature was measured are shown in Figure 5.28. The recording devices and the positions of the thermocouples for each recorder were connected as follows ... 

The heating of the furnace is accomplished using 4 cylindrical resistances wired up in parallel, so that the total resistance is 35 2. These four resistances are placed inside the stainless steel block. A thermoelectric couple is plaeed just below the furnace surface. The regulation of the temperature is ensured by a temperature regulator-programmer. 

Fig. 5. Schematic diagram of the preparative TREF system (a) oven (b) three-way valve (c) column (70-mm i.d., 1000 mm) (d) thermoelectric couple (e) preheating column (/) stop valve (g) relief valve (h) pressure gauge (i) pump (/) filter (fe) solvent tank (f) solution tank (m) constant-pressure valve (n) Nj inlet, (Usami, Gotoh and Takayama [10]) Reprinted with permission copyright 1986 Amer. Chem. Soc,...

The reason stems from the specificity of an ideal gas which is to enforce equality between two coupling energies, the hydrodynamical-physical chemical coupling energy and the thermal-physical chemical one. This holds for the ideal gas but not for a real gas and it is not a standard property of the thermal energy the thermoelectric coupling, for instance, does not enter in this category. 

The thermoelectric voltage developed in a thermoelectric couple is a function of the temperature difference between the measured and reference sites. The reference ends are connected with further conductors in an electrically and thermally insulated space to avoid parasitic voltages (compensation leads, shielded conductors, shortest path to encircle smallest possible, holder induced leaks). Temperature measurements by thermoanalytical instruments are conventionally calibrated by a set of ICTAC-approved standards, convenient for both the DTA/DSC [594,614] and TG [615] techniques. 

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