Brayton air cycle

A four-stage reheat and four-stage intercool Brayton air cycle as shown in Fig. 4.44a has been designed by a junior engineer with the following design input information ... 

Figure 4.44a Four-stage reheat and four-stage intercool Brayton air cycle.

Figure 4.44e Brayton air cycle design parameter optimization. 

Combined Brayton-Rankine Cycle The combined Brayton-Rankine cycle. Figure 9-14, again shows the gas turbine compressor for the air flow to the cell. This flow passes through a heat exchanger in direct contact with the cell it removes the heat produced in cell operation and maintains cell operation at constant temperature. The air and fuel streams then pass into the cathode and anode compartments of the fuel cell. The separate streams leaving the cell enter the combustor and then the gas turbine. The turbine exhaust flows to the heat recovery steam generator and then to the stack. The steam produced drives the steam turbine. It is then condensed and pumped back to the steam generator. 

Determine the power required by the compressor, power required by pumps 1 and 2, power produced by turbine 1, 2, and 3, rate of heat added to the Brayton cycle, net power produced by the Brayton gas turbine plant, net power produced by the steam Rankine plant, rate of heat exchanged in the heat exchanger 1, rate of heat added to the R-12 Rankine plant, mass rate flow of air in the Brayton cycle, mass rate flow of steam in the Rankine steam plant, mass rate flow of R-12 in the Rankine R-12 plant, cycle efficiency of the Brayton plant, cycle efficiency of the steam Rankine plant, cycle efficiency of the R-12 Rankine plant, and cycle efficiency of the triple plant. 

A Brayton/Rankine cycle (Fig. 5.12) uses water as the working fluid with 1 kg/sec mass flow rate through the Rankine cycle, and air as the working... 

Gas-Cycle Systems. In principle, any permanent gas can be used for the closed gas-cycle refrigeration system however, the prevailing gas that is used is air. In the gas-cycle system operating on the Brayton cycle, all of the heat-transfer operations involve only sensible heat of the gas. Efficiencies are low because of the large volume of gas that must be handled for a relatively small refrigera tion effect. The advantage of air is that it is safe and inexpensive. 

The surprise was finally clarified by remembering that this was an air operated plant built in a thermodynamic cycle, (the Brayton or gas turbine cycle) with a 18,000 HP air compressor. This generated 5 MW of salable... 

A simplified application of the first law of thermodynamics to the air-standard Brayton cycle in Figure 2-1 (assuming no changes in kinetic and potential energy) has the following relationships ... 

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. 

The Joule-Brayton (JB) constant pressure closed cycle is the basis of the cyclic gas turbine power plant, with steady flow of air (or gas) through a compressor, heater, turbine, cooler within a closed circuit (Fig. 1.4). The turbine drives the compressor and a generator delivering the electrical power, heat is supplied at a constant pressure and is also rejected at constant pressure. The temperature-entropy diagram for this cycle is also... 

El-Masri, M.A. (1987a). Exergy analysis of combined cycles Part 1 Air-cooled Brayton-cycic gas turbines. ASME J. Engng Power Gas Turbines 109. 228-23. i. 

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