Peltier thermoelectric device

Nelson, R. J., Paulus, A., Cohen, A. S., Guttman, A., and Karger, B. L., Use of Peltier thermoelectric devices to control column temperature in high-performance capillary electrophoresis, /. Chromatogr., 480, 111, 1989. 

Because the numerator is large (e.g. Cu Ka is 8.04keV) and the denominator small, that is, of the order of electron volts, a large number of electron-hole pairs are produced by each photon. The Si(Li) detectors must be kept at liquid nitrogen temperature at all times in order to minimize thermal excitation of electrons and to prevent lithium thermal diffusion. Either a Dewar vessel or a Peltier thermoelectric device is used in conjunction with the solid state detector. 

Typical values for h in CE instruments are approximately 50 Wm for stagnant air [21], 300-700 Wm K for fan-forced air depending on the speed of flow and the fraction of the capillary that is temperature controlled [8,21] and between 700 and 1200 Wm for liquid cooling [5,22]. The most effective cooling system to be demonstrated for CE used a Peltier thermoelectric device to cool an alumina block. The capillary was housed in a purpose built groove and thermal contact was enhanced using ethylene glycol. A heat transfer coefficient of h = 2600 Wm" K was reported for this device [10],... 

Where cooling is required as well as heating, a closed loop refrigeration circuit, servoed in a similar manner, can be used. A more sophisticated temperature controller, which can both heat and cool, can be made from a Peltier thermoelectric device. In this device a voltage across a series of thermocouple junctions sets up a temperature... 

Thermoelectric materials have been used extensively for thermal sensing, energy conversion (heat to electricity), and for cooling (Peltier effect). In general, thermoelectric devices consist of n-type and p-type semiconductor constituents connected electrically in series and thermally in parallel [151]. While energy conversion efficiencies for thermoelectric devices are not yet competitive with conventional refrigerator or power generation systems, it is possible to achieve enhanced efficiencies... 

A solar ammonia-carbon ice maker produced 500 kg ice per day.184 Electricity from photovoltaic cells can also be used to run refrigerators.185 Photovoltaic cells were also used to power a thermoelectric device using the Peltier effect (which involves passing a current through a junction of two dissimilar metals) to reach —3°C.186 The system has no moving parts and is small, lightweight, reliable, noiseless, portable, and is potentially low-cost when mass-pro-... 

Thermoelectric devices can also be used for cooling. By forcing a current through the material, a temperature gradient is created. This is the inverse of the Seebeck effect and is referred to as the Peltier effect. 

Temperature Control in Mkrofluidk Systems, Fig.l Contact extemal heating methods for microfluidic devices (a) heat exchanger heater [1], (b) Peltier thermoelectric heater [2], and (c) thin resistive heater [3]... 

Currently the most popular cooling method is the externally controlled passive cooling technique using traditional convection heat transfer and heat exchanging techniques such as fins [1], a fan [3], and compressed air for microfluidic device cooling. Integrated cooling techniques for microfluidic devices are very limited such as the Peltier thermoelectric cooler [2] and endothermic cooler [7] mentioned above. 

A fourth method of cooling infrared detection cells is the thermoelectric device which utilizes the Peltier effect. This is a reverse thermocouple. When current is applied to it, one side of the dissimilar metal junction turns cold. These devices, while very reliable, are presently.capable of cooling to no lower than -100°F, whereas required cooling is to the order of -300°F, or lower. 

The primary thermoelectric phenomena considered in practical devices are the reversible Seebeck, Peltier, and, to a lesser extent, Thomson effects, and the irreversible Eourier conduction and Joule heating. The Seebeck effect causes a voltage to appear between the ends of a conductor in a temperature gradient. The Seebeck coefficient, L, is given by... 

---