Peltier power

Heating or cooling power at the junction (Peltier power)... 

The CPA [188], marketed by ThermoMetric AB (Sweden), is frequently used in Europe. It operates on the principle of power compensation, which is based on the supply or withdrawal of heat to and from the reactor, respectively, in order to keep the temperature at the set-point and, thus, to compensate for energy differences (either shortage or surplus). The heat is supplied or withdrawn by means of special (Peltier) elements, which produce a cold or a hot surface area if subjected to an electrical current. An accurate measurement of the heat supply/withdrawal is possible as the heat flow is directly proportional to the current supplied to the Peltier elements. 

The reverse of the Seebeck effect is called the Peltier effect and results from flowing an electric current through the circuits of figure 9.1. If the junctions are initially at the same temperature, a temperature gradient will be developed for instance, in the case of figure 9.1a, one of the junctions will cool and the other will warm. Associated with this electric current there will also be a Joule (resistive) effect, so that the net power (P) produced at each junction is given by... 

Yet it will be necessary to look for systems having higher conductivities, since a Peltier refrigerator, for example, would become competitive in its power consumption only above an effectivity of Gx = 6 x 10-3 deg-1. It is probable that this aim will be reached. Table 12 shows a Cu-polyphthalocyanine sample with a remarkably favorable Gx value of about 5 x 10 4 deg-1. 

The experimental arrangement of LA-ICP-MS using a powerful laser ablation system coupled to a double-focusing sector field ICP-MS (Element, Thermo Fisher Scientific, Bremen) is shown in Figure 5.22. A cooled laser ablation chamber using two Peltier elements in serial connection... 

The thermoelectric power tensor A is not symmetric because A = a 1f3, and although the ORRs require a to be symmetric, this is not true of the off-diagonal 71(2) 8. Equation (24) shows that when there is no temperature gradient, a flow of electric current produces heat (the Peltier effect), the magnitude of which is determined by A8... 

Fig. 8.1 Standard set-up of a reaction calorimeter [4]. Left side heat-flow, heat-balance and power-compensation calorimeters. Right side Peltier calorimeters.

Fig. 8.2 Main heat-flow rates that have to be considered in heat-flow, heat-balance and power-compensation reaction calorimeters running under strictly isothermal conditions [4]. The heat-flow rates inside a Peltier calorimeter are analogous (compare with Fig. 8.1). The direction of the heat-flow arrows corresponds to a positive heat-flow rate. For explanation of the different heat-flow rates, see the text.

The calorimeter that has been used to obtain the results presented in this section basically combines the power-compensation and heat-balance principles (see Sections 8.2.2.2 and 8.2.2.3). The heat-balance principle is implemented by Peltier elements [18]. This new... 

It must be noted that increasing the amount of solvent in the ICP produces a higher load on the plasma and an increase in reflected powers, causing plasma instability. Desolvation of the sample aerosol may overcome this hurdle and is achieved by the use of a cooled spray chamber. In addition, Peltier coolers and membrane dryers [23] have been used for desolvating liquid aerosols and eliminate approximately 90% of the aerosol (Fig. 10.3). Spray chambers may also im-... 

Electrochemical calorimetry — is the application of calorimetry to thermally characterize electrochemical systems. It includes several methods to investigate, for instances, thermal effects in batteries and to determine the -> molar electrochemical Peltier heat. Instrumentation for electrochemical calorimetric studies includes a calorimeter to establish the relationship between the amount of heat released or absorbed with other electrochemical variables, while an electrochemical reaction is taking place. Electrochemical calorimeters are usually tailor-made for a specific electrochemical system and must be well suited for a wide range of operation temperatures and the evaluation of the heat generation rate of the process. Electrochemical calorimeter components include a power supply, a device to control charge and discharge processes, ammeter and voltmeter to measure the current and voltage, as well as a computerized data acquisition system [i]. In situ calorimetry also has been developed for voltammetry of immobilized particles [ii,iii]. 

Diathermal-compensation calorimeters here again, sample temperature follows surroundings temperature (usually constant in adsorption experiments), but now by means of a power compensation within the sample cell (i.e. Joule or Peltier effect). This reduces the response time. 

By two dimensional (2D) imaging of brain tissues, a defined sample area (several cm ) of a thin section of brain tissue (thickness 20(j,m) was ablated hue by line with a focused laser beam in a cooled laser ablation chamber (using two Peltier elements behind the target holder made of aluminium). The spot size of the laser beams was about 50(xm, the laser power density 3 x 10 Wcm . Ion intensities of the analytes, e.g., P+, Cu or Zn , were... 

While the Seebeck effect enables TE devices to be used for power generation, the Peltier effect allows them to be used for cooling. In Peltier effect devices, heat flows in the same direction as majority carriers. The appropriate metric for this apphcation is called the TE efficiency, t], which is simply the ratio between the load s power input and the net heat flowrate. Essentially, rj gives the fraction of Camot efficiency attainable... 

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... 

The measurement of thermoelectric properties employed the DC method with high speed and high resolution[2] to remove fully errors occurring by Peltier effect. The thermo-electromotive force o was measured as a function of temperature difference AT at both ends of a specimen. The thermoelectric power a was obtained from a slope of o-A Tcurve and expressed as an absolute value. 

Figure 12.8 The two mtegories of detectors used for energy dispersive X-ray fluorescence spectrometry. (a) Proportional counter used in pulse mode (b) Cooled Si/Li diode detector using Peltier effect (XR detector by Amptek Inc.) (c) Functioning principle of a scintillation detector containing a large size reverse polarized semi-conductor crystal. Each incident photon generates a variable number of electron-hole pairs. The very high quantum yield enables the use of low power primary sources of X-rays (a few watts or radio-isotopic sources).

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-... 

Polymerase chain reaction (PCR) is a powerful method for DNA amplification (i), which is routinely used for detection and analysis of DNA. Many commercial thermocyclers employ a Peltier chip (2-4), which is a solid-state technology that can be used for heating or cooling. Peltier systems are widespread and provide a... 

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