Thermodynamic Cycle Efficiencies

Another reason for the increased use of gas turbines as prime movers in the process industry is the high thermodynamic cycle efficiencies and subsequent low operating cost. 

A recent comprehensive study [16] shows that the ideal detonative cycle is indeed more efficient than the ideal constant-volume Humphrey and the ideal constant-pressure Brayton cycles under all conditions. The relative advantage does decrease with increasing inlet compression temperature ratios and, hence, will decrease with increasing flight Mach numbers. The thermodynamic cycle efficiencies have been related to overall performance measures using conventional steady-state analysis. The appropriateness of this approach to an inherently unsteady device is debatable but is worth considering as an additional performance estimate. 

The power circuit is a gas turbine one with closed circuit and complex thermodynamic cycle. As it was already mentioned, the operating medium is a mixture of argon and nitrogen gases. The thermodynamic cycle efficiency is 42%. 

These data correspond to a conservative variant of SVBR-75/100 using available SGs and saturated steam turbine, with the maximum temperatures of fuel element claddings not exceeding 600°C. Currently, the work to increase the temperature of the fuel element cladding up to 650 C is being conducted that would make it possible to increase the reactor thermal power by -15% and enhance the possibility of a transfer to a superheated steam turbine cycle that worrld resrrlt in the increase of the thermodynamic cycle efficiency by -15%. In calcrrlations of the preserrted technical and economic parameters, an additional margin of 17% over the normative parameter values has been introduced, which corresponds to 60% of the reactor installation eqrripment cost. 

The quality of the steam produced by the steam generators must be sufficient to ensure good thermodynamic cycle efficiency and to minimise turbine blade erosion. 

During operation at power, it heats the feed water to the optimum temperature for maximising the thermodynamic cycle efficiency. 

It extracts some of the wetness from the steam as it expands through the turbine cylinders by selectively bleeding relatively wet steam for its feed heaters, thereby improving thermodynamic cycle efficiency and minimising turbine blade erosion. 

It was pointed out in Chapter I that the desire for higher maximum temperature (T nx) in thermodynamic cycles, coupled with low heat rejection temperature (Tmin), is essentially based on attempting to emulate the Carnot cycle, in which the efficiency increases with... 

This remarkable result shows that the efficiency of a Carnot engine is simply related to the ratio of the two absolute temperatures used in the cycle. In normal applications in a power plant, the cold temperature is around room temperature T = 300 K while the hot temperature in a power plant is around T = fiOO K, and thus has an efficiency of 0.5, or 50 percent. This is approximately the maximum efficiency of a typical power plant. The heated steam in a power plant is used to drive a turbine and some such arrangement is used in most heat engines. A Carnot engine operating between 600 K and 300 K must be inefficient, only approximately 50 percent of the heat being converted to work, or the second law of thermodynamics would be violated. The actual efficiency of heat engines must be lower than the Carnot efficiency because they use different thermodynamic cycles and the processes are not reversible. 

No thermodynamic cycle can be more efficient than a reversible cycle operating between the same temperature limits. 

Lithium metal is chemically very active and reacts thermodynamically with any organic electrolyte. However, in practice, lithium metal can be dissolved and deposited electrochemically in some organic electrolytes [5]. It is generally believed that a protective film is formed on the lithium anode which prevents further reaction [6, 7]. This film strongly affects the lithium cycling efficiency. 

On-site combined heat and power (CHP) which has existed for years, includes turbines, reciprocating engines and steam turbines. Gas turbines in the 500-kW to 250-MW produce electricity and heat using a thermodynamic cycle known as the Brayton cycle. They produce about 40,000-MW of the total CHP in the United States. The electric efficiency for units of less... 

In the conversion of fossil and nuclear energy to electricity, the value of high temperature solution phase thermodynamics in improving plant reliability has been far less obvious than that of classical thermodynamics in predicting Carnot cycle efficiency. Experimental studies under conditions appropriate to modern boiler plant are difficult and with little pressure from designers for such studies this area of thermodynamic study has been seriously neglected until the last decade or two. 

Following the first successful examples of catalytic antibodies raised against haptens as transition state analogues (TSAs) reported by Lerner and Schultz, the TSA approach has been applied in a large number of studies in order to generate new biocatalysts for many chemical transformations. According to the transition state theory, the catalytic efficiency ( cat/ uncat) of given enzymatic reaction can be deduced from the thermodynamic cycle (Scheme 1) under ideal conditions. ... 

Determine the thermodynamic efficiency and the net power output of the Braysson combined plant. Plot the sensitivity diagram of rj (cycle efficiency) versus (pressure at state 6) and sensitivity diagram of r] (cycle efficiency) versus pg (pressure at state 8). 

An engine concept that utilizes a more efficient thermodynamic cycle that consumes less fuel, and is simple and capable of operation at both subsonic as well as supersonic speeds, would be an attractive alternative for future propulsion systems. Pulse detonation engines (PDE), in principle, can provide higher efficiency [9], and better performance over a wide range of operating conditions, with fewer moving parts. 

Bell, L.E.PhD BSST, LLC5462 Irwindale Avenue, Irwindale CA 917061bell amerigon.com, 626.815.7430. Alternate Thermoelectric Thermodynamic Cycles with Improved Power Generation Efficiencies. 

Excited-state proton transfer relates to a class of molecules with one or more ionizable proton, whose proton-transfer efficiency is different in the ground and excited states. The works of Forster [2-4] and Weller [5-7] laid the foundation for this area on which much of the subsequent work was based. Forster s work led to the understanding of the thermodynamics of ESPT. He constructed a thermodynamic cycle (Forster cycle) which, under certain acceptable approximations, provides the excited-state proton-transfer equilibrium constant (pK f,) from the corresponding ground-state value (pKa) and electronic transition energies of the acid (protonated) and base (deprotonated) forms of the ESPT molecule ... 

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