Output work

For NO control only, steam is injected into the combustor directly to help reduce the primary zone temperature in the combustor. The amount of steam injected is in a ratio of 1 1 with the fuel. In this cycle, the steam is injected upstream of the combustor and can be as much as 5-8 percent by weight of the air flow. This cycle leads to an increase in output work and a shght increase in over l efficiency. Corrosion problems due to steam injection have been for the most part over-... 

To obtain a more accurate relationship between the overall thermal efficiency and the inlet turbine temperatures, overall pressure ratios, and output work, consider the following relationships. For maximum overall thermal cycle efficiency, the following equation gives the optimum pressure ratio for fixed inlet temperatures and efficiencies to the compressor and turbine ... 

The optimum pressure ratio for maximum output work for a turbine taking into aeeount the effieieneies of the eompressor and the turbine expander seetion ean be expressed by the following relationship ... 

The addition of an intercooler to a regenerative gas turbine cycle increases the cycle s thermal efficiency and output work because a larger portion of the heat required for the process c-3 in Figure 2-7 can be obtained from the hot turbine exhaust gas passing through the regenerator instead of from burning additional fuel. 

A simple cycle with intercooler can reduce total compressor work and improve net output work. Figure 2-7 shows the simple cycle with intercooling between compressors. The assumptions made in evaluating this... 

The cycle leads to an increase in output work and an increase in overall thermal efficiency. 

Figure 2-28 and 2-29 give a good comparison of the effect of the various cycles on the output work and thermal efficiency. The curves are drawn for a... 

The work required to drive the turbine eompressor is reduced by lowering the compressor inlet temperature thus increasing the output work of the turbine. Figure 2-35 is a schematic of the evaporative gas turbine and its effect on the Brayton cycle. The volumetric flow of most turbines is constant and therefore by increasing the mass flow, power increases in an inverse proportion to the temperature of the inlet air. The psychometric chart shown shows that the cooling is limited especially in high humid conditions. It is a very low cost option and can be installed very easily. This technique does not however increase the efficiency of the turbine. The turbine inlet temperature is lowered by about 18 °F (10 °C), if the outside temperature is around 90 °F (32 °C). The cost of an evaporative cooling system runs around 50/kw. 

Vehicle fuel economy is normally measured in miles per gallon. At any given instant, it depends on the energy content of a gallon of fuel (Qf), the vehicle velocity (V.,) and power required (P,-5q), the thermal efficiency with which the engine converts fuel energy into useful output work (rj,.), and the mechanical efficiency with which the driveline delivers that work to the vehicle wheels (r j). Specifically,... 

The horizontal line at the bottom of the pressure-volume diagram of Figure 4 traces the other tv o strokes of the four-stroke cycle. On the exhaust stroke, from 5 to 6, the rising piston expels most of the remaining combustion products from the cylinder. On the intake stroke, from 6 to 7 (= 1), the descending piston inducts a fresh charge for repetition of the cycle. The net thermodynamic work developed in this cycle is proportional to the area enclosed by the pressure-volume diagram. In the ideal case, both the exhaust and intake strokes occur at atmospheric pressure, so they have no effect on the net output work. That justifies their exclusion from the thermodynamic representation of the ideal Otto... 

After these preliminaries, the question of efficiency to lowest order in AT/T can be addressed following the analysis given in Ref. 32. Errst we rewrite the efficiency, output work over input heat, as the output power over input heat flux. In Eq. (1) this corresponds to dividing nominator and denominator by the time required for the process under consideration. When operating under steady-state conditions, as we are doing here, the latter quantities are also the time... 

The measurement of performance for a heat engine is ealled the thermal efficiency, r]. The thermal efflcieney of a heat engine is defined as the ratio of the desirable net output work sought to the heat input of the engine = IT et/6inpuf... 

The overall efficiency of the combined cycle is the total output work (lVi + IV2) divided by the heat input, Qi. Referring to Fig. 5.3, we have... 

Thus the output work AA >0 should be genarated without any lost heat and by the direct change of the whole heat AQW-AQ w but within the cycle OO. For r/mlmechanical work. We see that AA =0 is the reality. 

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