Cold combustion

The simplest configuration for a recuperative heat exchanger is the metallic radiation recuperator (Fig. 27-57). The inner tube carries the hot exhaust gases and the outer tube carries the combustion air. The bulk of the heat transfer from the hot gases to the surface of the inner tube is by radiation, whereas that from the inner tube to the cold combustion air is predominantly by convection. 

A number of analytic determinations of reaction products by taking samples as described above have been made. The results show, that the oxygen consumption in the flame is nearly complete, with CO2 and CO as major products. At temperatures below flame ignition, cold combustion was also detected with a similar range of products. 

Chronopotentiometry, galvanostatic transients, 1411 as analytical technique, 1411 activation overpotential, 1411 Clavilier, and single crystals, 1095 Cluster formation energy of, 1304 and Frumkin isotherm, 1197 Cobalt-nickel plating, 1375 Cold combustion, definition, 1041 Cole-Cole plot, impedance, 1129, 1135 Colloidal particles, 880, 882 and differential capacity, 880 Complex impedance, 1135 Computer simulation, 1160 of adsorption processes, 965 and overall reaction, 1259 and rate determining step, 1260... 

Dioxygen, 02, is a vital part of the metabolism of higher organisms that respire aerobically. It is used to metabolically oxidise sugars such as glucose and sucrose (Equation 2.7) with an associated release of energy. The energy from this controlled cold combustion is used in ATP synthesis. 

Figure 9 Reaction sequence of the electrochemical combustion of phenol. (>i) Chemical reaction of adsorbed hydroxyl radicals with the organic molecule. (r2) Electrochemical cold combustion to CO, of adsorbed organic molecules. (From Ref. 41.)...

E. Justi and J. Winsel, Cold Combustion, Verlag, Chemie, Wiesbaden, Germany (1962). A general account of fuel cells before the 1960s. 

A fuel cell can be thought of as a cold-combustion power source that generates electrical energy directly from (stored) chemical energy. Due to minimal heat transfers, it is unfettered by conversion-efficiency hmitations characteristic of hot-combustion devices. Unlike batteries, but similar to internal combustion engines, a fuel cell is a continuous-flow system in which fuel and oxidant are externally supplied for operation. In a functional hydrogen-fuel cell, H2 gas is introduced through feed plates to the anode compartment. At the same time, but to the cathode in a separate chamber, O2 gas delivered. At the anode, H2 is oxidized to H ... 

When compared to diesel fuel the emissions of CO and HC are higher for bio-oil. The results indicate slightly lower NOx emissions for bio-oil. All measurements were taken at part load operation due to the limitation of the gas turbine. The initial tests in dual-fuel-mode were performed with a relatively cold combustion at part load which may be the reason for the incomplete combustion of the hydro carbons. Also the combustion air fuel ratio was not adjusted for bio-oil operation at part load. The combustion of bio-oil is clearly recognised by the exhaust gas odour and a light exhaust gas cloudiness. 

Based on the continuity of temperature gradient at y = 5r, we have the condition of ignition of a cold combustible stream ... 

Materials other than hydrogen can serve as ionic energy carriers too—for example, carbon (as a carbonate ion) and oxides of various elements. In theory, any substance capable of chemical oxidation that can be supplied continuously (as a fluid) can be burned as the fuel at the anode of a fuel cell, Appleby and Foulkes explain. This overall reaction may be viewed as the cold combustion of hydrogen with oxygen —cold combustion... 

Reversible fuel cells—systems that can be switched between producing electricity from the cold combustion of hydrogen and oxygen and splitting water again into hydrogen and oxygen by electrolysis—were first devel-... 

Because of the key role which oxygen plays it seems to be worthwhile to discuss first of all some of its properties making this substance the fittest oxidant in the biological world, before going into details of the realization of metabolic cold combustion . 

The overall reaction is basically the spontaneous cold combustion of hydrogen. In contrast to a combustion process, however, the fuel and oxidant in a fuel cell are kept separate and are never mixed. In the fuel cell, little heat is liberated and instead the free energy is released directly as electrical energy. Hence, the maximum energy efficiency is written as... 

The fuel oxidizes at the fuel cell s anode and oxygen reduces at the cathode. In total, the hydrogen undergoes a process of cold combustion where it turns into water. The cell voltage (at 200 °C and 4 MPa) is about 1.2 V. 

Preheating combustion air is accomplished by recuperators or regenerators, discussed in detail in chapter 5. Recuperators are steady-state heat exchangers that transmit heat from hot flue gases to cold combustion air. Regenerators are non-steady-state devices that temporarily store heat from the flue gas in many small masses of... 

Boilers and low temperature applications sometimes use a heat wheel regenerator—a massive cylindrical metal latticework that slowly rotates through a side-by-side hot flue gas duct and a cold combustion air duct. 

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