Residue thermal energy

Thermal energy, power generation, and incineration have several factors in common. All rely on combustion, which causes the release of air pollutants all exhaust their emissions at elevated temperatures and all produce large quantities of ash when they consume solid or residual fuels. The ratio of the energy used to control pollution to the gross energy produced can be a deciding factor in the selection of the control system. These processes have important differences which influence the selection of specific systems and devices for individual facilities. 

The combination of the fuel cell and turbine operates by using the rejected thermal energy and residual fuel from a fuel cell to drive the gas turbine. The fuel cell exhaust gases are mixed and burned, raising the turbine inlet temperature while replacing the conventional combustor of the gas turbine. Use of a recuperator, a metallic gas-to-gas heat exchanger, transfers heat from the gas turbine exhaust to the fuel and air used in the fuel cell. 

In most of today s ethanol plants for the conversion of wheat, rye and corn, the required thermal energy is provided by natural gas, heavy fuel oil or coal. The protein-rich by-products of ethanol plants are referred to as dried distillers grains with solubles , abbreviated as DDGS, and are mostly used for animal fodder. Alternatively, they can be converted to biogas for heat and electricity production. The resulting residue can then be used as fertiliser (see Table 7.16). 

E.g. tryptophane residues of proteins excite at 290-295 mn but they emit photons somewhere between 310 and 350 mn. The missing energy is deposited in the tryptophane molecular enviromuent in the form of vibrational states. While the excitation process is complete in pico-seconds, the relaxation back to the initial state may take nano-seconds. While this period may appear very short, it is actually an extremely relevant time scale for proteins. Due to the inherent thermal energy, proteins move in their (aqueous) solution, they display both translational and rotational diffusion, and for both of these the characteristic time scale is nano-seconds for normal proteins. Thus we may excite the protein at time 0 and recollect some photons some nano seconds later. With the invention of lasers, as well as of very fast detectors, it is completely feasible to follow the protein relax back to its ground state with sub-nano second resolution. The relaxation process may be a simple exponential decay, although tryptophane of reasons we will not dwell on here display a multi-exponential decay. 

When one considers the early 2000 s, it can be expected that about one half of the thermal energy will be supplied by natural gas, and the rest by petroleum fuels (fuel oil and residual oil) and coal. Coal is assumed to be the main energy source for electricity generation, gasoline for surface transportation, and jet fuel for air transportation. This is of course a simplified version of the fossil fuel energy system, but it is close enough to the present patterns of energy consumption, and can be used as the basis for comparisons. 

As the temperature is reduced, the thermal energy available to overcome kinetic barriers to the lowest-energy state is reduced and, in some cases, residual entropy is difficult to remove at low temperatures. In other words, in the low-temperature cooling of these substances, reversibility cannot be approached. An example of a substance with residual entropy is solid CO. Carbon monoxide has a very small dipole moment, which indicates that there is a preferential orientation of molecules at low temperature. The magnitude of the dipole is so small, however, that at temperatures at which the preference becomes appreciable, there is insufficient thermal energy to overcome kinetic barriers for rotation of the molecules in the solid. 

J. M. F. Douse, Dynamic Headspace Method for the Improved Clean-up of Gunshot Residues prior to the Detection of Nitroglycerine by Capillary Column Gas Chromatography with Thermal Energy Analysis Detection, Journal of Chromatography 464 (1989) 178. 

Tine DH, Yu WC, Goff EU, et al. 1984. Picogram analyses of explosive residues using the thermal energy analyzer (TEA). J Forensic Sci 29 732-746. 

A thermos bottle (Dewar vessel) has an evacuated space between its inner and outer walls to diminish the rate of transfer of thermal energy to or from the bottle s contents. For good insulation, the mean free path of the residual gas (air average molecular mass = 29) should be at least 10 times the distance between the inner and outer walls, which is about 1.0 cm. What should be the maximum residual gas pressure in the evacuated space if T = 300 K Take an average diameter of d = 3.1 X 10 °m for the molecules in the air. 

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