Brayton cycle Temperature Effect

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 effectiveness of the regenerative Brayton cycle performance will depend on the efficiency of the fuel cell, compressor, and turbine units the pressure loss of gases flowing through the system the approach temperatures reached in the recuperative exchanger and, most importantly, the cost of the overall system. 

Consider a simple ideal Brayton cycle with fixed turbine inlet temperature and fixed compressor inlet temperature. What is the effect of the pressure ratio on the cycle efficiency ... 

The production of electrical power at higher efficiency via a Brayton Cycle and hydrogen production requires both heat at higher temperatures, up to 1000°C, and high effectiveness heat exchange to transfer the heat to either the power or process cycle. This presents new challenges for heat exchangers. If plant efficiencies are to be improved there is a need for ... 

The 100°C seawater exiting from the Brayton cycle cooler delivers heat and seawater feedstock to the desalination plant. The desalination plant is a feed forward Multi-Effect-Distillation (MED) design [10], which produces 8000 m /d of potable water. Finally, heat at temperature slightly above ambient exits the plant in the form of heated brine tailings from the desalination process - minimizing the thermal plume ecological footprint of the plant. Alternate bottoming cycles have been identified for use at landlocked sites. 

More recent studies have been carried out on the corrosion behavior of steels and nickel-base alloys in extreme conditions for the CO2 environment, with temperature up to 750°C and pressures up to 250 bar [31—43] in support to the Brayton cycle. A compilation of the main conclusions of all these results is proposed below. The effects of parameters relating to the environment such as CO2 pressure or the amount of impurities in CO2 and the effect of parameters concerning the alloy such as the alloy composition and the alloy surface finish are highlighted. 

Figure 9-34 Estimated effects of recuperator interchannel leak size on Brayton cycle performance. (Modeling Assumptions for Symbols (1) Single unit Brayton generating 100 kWe (2) Turbine inlet temperature is fixed at 1150K (3) Leakage does not impact turbine flow (4) Reduced compressor/turbine efficiencies are not considered in the impact on power output (5) Changes in pressure losses are not...

Sensitivities to the main Brayton cycle design power operating parameters including compressor inlet pressure, compressor pressure ratio, compressor inlet temperature, turbine inlet temperature, recuperator and gas cooler effectiveness, and total AP of loop are discussed in Section 5.0. The following design constraints have been used to guide the current design state points ... 

FIG. 29-39 Performance map showing the effect of pressure ratio and tiirhine inlet temperature on a Brayton-Ranidne cycle. 

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