Heating device efficiency

The heat supply to the cyclic gas turbine power plant of Fig. 1.2 comes from the control surface Z. Within this second control surface, a steady-flow heating device is supplied with reactants (fuel and air) and it discharges the products of combustion. We may define a second efficiency for the heating device (or boiler) efficiency. 

The overall efficiency of the entire gas turbine plant, including the cyclic gas turbine power plant (within T) and the heating device (within Z), is given by... 

Laboratory ELITE explosives detection device. Similarly to the aforementioned ETK, it can detect traces of mOitary, as well as homemade explosives, by applying the common Meisenheimer and Griess reagents. Because of the addition of a heating device nd efficient swiping for sample collection, the reported sensitivity of ELITE is 2—50 times higher than that of other commercial field tests [102]. For example, ELITE detection limits for TNT, 2,4-DNT, and tetryl were found to be 50, 100, and 50 ng, respectively. Lower thresholds (25—50ng) were reported for PETN, RDX, HMX, and NC [102]. 

By evaluating the performance of micro heat exchangers, the temperature changes of heat transfer fluids were used, and the heat transfer efficiency of devices made of stainless steel or glass were found to be higher than that of devices made of copper (see Table 4.2). 

For reactors of a larger diameter (e.g. more than 600 mm) it is more advisable to use a bundle of small tubes as heat exchangers. Such a distribution of heat exchange surfaces virtually does not inhibit fluidising and ensures that the heat is efficiently withdrawn from the whole surface of the apparatus. It should be also kept in mind that tube bundles allow one to select the reaction space and place rotating gas distribution devices between sections this considerably increases the coefficient of heat transfer and ensures a more uniform gas distribution in the reaction zone. 

Fuel cells Chemical energy —> electrical energy (continuous supply of gaseous components) Power plants Heat-power devices (efficient fuel conversion)... 

We consider the case of a discontinuous organic synthesis, which occurs in a liquid medium undergoing intensive agitation the temperature is controlled by an external heating device. The process efficiency is characterized by the conversion defined here as the ratio between the quantity of the useful species obtained and the theoretical quantity of the same species. This last value is fixed by the thermo-... 

Typically, microfluidic devices have channels with dimensions between 10 and 400 pm. This small dimension compared to conventional mixing systems results in an increase in the surface-to-volume ratio, to 10,000-50,000 m m compared with 100-2,000 m m of their macroscale counterparts. This characteristic endows micromixers with a superior heat transfer and control [192], allowing reactions to be performed in an isothermal manner [83, 193, 194]. Due to their heat transfer efficiency, micromixers can be conveniently applied for handling reactions in which fast heating and cooling of the reaction mixture are required, such as highly exothermal reactions [9, 195-199]. 

With zeoUtes it is possible to compensate charging by heating the sample in situ to temperatures where either proton, cation or oxygen anion conductivity causes a complete breakdown of the insulating properties of the sample [7]. Inert sample holders, a well-outgassed sample and a very inert vacuiun environment are required in addition to a field-free heating device for the successful application of this technique. It is Umited to thermally stable zeolite samples, as temperatures of about 650 K are required for efficient compensation. 

Pellet Stove - A space heating device that burns pellets are more efficient, clean burning, and easier to operate relative to conventional cord wood burning appliances. 

One of the most important applications of high-A ceramics is as substrates and packages for electronic devices as shown in Figure 34.9. Due to the complexity and density of modern electronic devices, efficient thermal management is important. Removal of heat from the semiconductor is essential to prevent thermally induced damage. 

A cookstove, like other combustion devices designed to produce useful heat, has two internal efficiencies that determine total efficiency (rjt). The combustion efficiency (r]c) indicates how much chemical energy in the fuel is converted to heat. The heat-transfer efficiency (rjf,) indicates what fraction of the heat produced goes into the heating vessels. Thus... 

Heat transfer coefficients have been calculated for studied devices (Figure 2.43) using thermal balance equations and considering the equations describing liquid media counter flow (heat exchange surface value F = 0.044 m for the diffnser-confnsor channel, F = 0,05 for the cylindrical charmel). Calculated results demonstrate that the heat transfer coefficient value is 1.4-1.7 times higher in diffnser-confnsor channels, than in cylindrical ones. The heat transfer efficiency of a cylindrical device shows a slight decrease in the transition area (Re = (4-10)10 ). 

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