Economic system thermodynamic efficiency

In view of the fact that the most important goal of the CHP systems described here is to achieve the interconversions of chemical, thermal, and mechanical energies with the highest efficiency and the lowest losses, these systems are ideal subjects of thermodynamic analyses. Since there are no chemical raw materials consumed and since the only delivered products are heat and work, thermodynamic efficiency of the overall process plays a vital role in the design and economics of such systems. It 1s the purpose of this report to present the results of two separate applications of the second law analysis to these chemical energy systems. 

Comparison of MEISs with traditional methods of equilibrium thermodynamics. Initial physico-mathematical assumptions. Physico-mathematical characteristics. Admissible and efficient spheres of application physics, chemistry, engineering systems, biology, and socio-economic systems. 

Economizers are one of several types of FW heaters, all of which are designed to provide thermodynamic gains in the steam cycle. They typically are located in the exit gas system, where their use improves overall boiler efficiency, which tends to increase by 1 % for every 40 to 50 °F (22-28 °C) reduction in flue gas temperature... 

Shakespeare s fairyland is mirrored in equilibrium thermodynamics all is simplicity and perfection For fuel cells, the gist of such a theory, tackled by Gardiner (1996), but challenged by Appleby (1994), is that the irreversible losses inherent in practical systems must be separated and evaluated. Then a comparison of practical with perfect, via a summation of the losses, leads to a calculated and understandable efficiency. The latter is an underlay to the economics, the final arbiter. The notion that the calorific value of the fuel, as distinct from its much larger chemical exergy, is a basis for performance calculations has been dismissed by Barclay (2002). In the foreword of this book, it is predicted that the novel ideas herein will get over, but rather slowly. But the ideas are not challenged. 

More efficient coal utilization can be realized with combined power plant cycles. For instance, the post combustion gases of a conventional combustor or an advanced MHD system can be further utilized to drive a gas or steam turbine. However, the sustained durability of downstream turbine or heat exchanger components requires minimal transport of corrosive fuel impurities. Control of mineral-derived impurities is also required for environmental protection. For the special case of open cycle-coal fired MHD systems, the thermodynamic activity of potassium is much higher in the seeded combustion gas (plasma) than in common coal minerals and slags. This results in the loss of plasma seed by slag absorption and is of critical concern to the economic feasibility of MHD. 

The chapters in this symposium volume illustrate the usefulness and develop the methodology of such Second Law analyses, now made much more comprehensible as a result of recent progress in Thermodynamics survey the results of efficiency analyses of a variety of processes, devices, systems, and economic sectors and teach the methods of engineering application of exergy to efficiency analysis and costing. 

Process integration and system synthesis require a skillful manipulation of system components. For example, heat exchanger network synthesis requires the utilization of very specialized methods of analysis [111, 112]. The search for an efficient system operation requires a multidisciplinary approach that will inevitably involve simultaneous utilization of heat transfer theory and thermal and mechanical design skills as well as specific thermodynamic considerations and economic evaluation. The optimal design of a system cannot be achieved without careful thermo-economic considerations at both system and component (i.e., heat exchanger) levels. 

From a thermodynamic perspective the essential difference between PSA and thermal swing processes is that in the PSA system the energy recfuired to achieve the separation is put into the system as mechanical work rather than as heat. Since mechanical energy is generally more expensive than heat, efficient utilization of energy is essential for an economic PSA system. Such considerations become especially important in the larger scale units. 

In recent years, these facts have significantly prompted the research toward the development of new and more efficient in situ regeneration systems of the NAD(P)(H) cofactors [2, 3], which allow their use in catalytic instead of stoichiometric amounts, thus making the dehydrogenase-catalyzed processes acceptable from an economical point of view. Moreover, the recycling reactions can be also used to shift the equilibrium of thermodynamically unfavorable transformations toward product formation. 

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