The working fluid is air modeled as an ideal gas. to panic, we will use only what we need to know to calculate Total Head. Kinetic and potential energy effects are negligible. There are no pressure drops for flow through the heat exchangers 4. The compressor and turbine are adiabatic. Small, single-stage steam turbines can have as low as 40 efficiency. Each component is analyzed as a control volume at steady state. The thermodynamic efficiency of multistage (moderate to high-pressure ratio) steam turbines ranges from 65 percent for very small (under 1,000 kW) units to over 90 percent for big industrial and utility-sized units. Schematic and Given Data: Engineering Model: 1. The compressor and turbine each have an isentropic etficiency Find: Determine the thermal efficiency, the back work ratio, and the net power developed, in kW. ture, and known compressor pressure ratio. Determine for the modified cycle (a) the thermal efficiency of the cycle each have an isentropic, (b) the back work efficie SOLUTION (nown: An air-standard Brayton cycle operates with given compressor inlet conditions, given turbine inlet tem- of80%. EXAMPLE 9.6 ating Performance of a Brayton Cycle with Irreversibilities der Example 9.4, but include in the analysis that the turbine and compressor Reconsid iency atio, (c) the net power developed, in kw. Work Done Rate by Turbine (Expanders) calculator uses Work Done Rate Change in EnthalpyMass Flow Rate to calculate the Work Done Rate, The Work Done Rate. 13 must be turbine and com be to brings out the effect of turbine and compressor irreversibilities on Example 9.6 plant perfor plant performance. tool for specific systems such as IC engines, gas turbine, etc. An air-standard analysis does not allow combustion irre- evaluated, however, and means introduced in Chap. The corresponding state TESTapp (thermodynamic calculator) can be can be launched by. 6.46 and 6.48, the and compressor are important, but the most significant by far is thesibility. TW cp (Tt4 - Tt5) Using algebra, we arrive at the equation: TW (nt cp Tt)4 1 - TPR ( (gam -1) / gam) that relates the work done by the turbine to the turbine pressure ratio, the incoming total temperature, some properties of the gas, and an efficiency factor nt. (c) Calculate (a) and (b) for the case where the turbine has an isentropic efficiency of 85. Isentropic turbine and irreversibilities of actual gas turbine power plants, irreversibilitics spectively are introduced in Sec. (b) The compressor exit pressure and temperature. Designating to 90% can now be achieved the states as Wlm) h-h (Wim)- TAKE NOTE. Transcribed image text: gas sor l ans turbine and compressor efficiencies are given by turbine 80 h 1, the isentropic turbine power plants.
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