Category: Gas Turbines

A gas turbine unit receives air at 100 kPa and 300 K and compresses it adiabatically to 620 kPa. The fuel has heating value of 44180 kJ/kg and fuel/air ratio is 0.017 kg fuel per kg air. The isentropic efficiencies of the compressor and the turbine are 88% and 90%, respectively. Calculate the compressor work,…

The thermodynamic analysis of the gas cycle shows that the efficiency of the cycle depends on the range of maximum temperature of the gas. If maximum temperature is increased, efficiency of the cycle is also increased. Any increase in the maximum temperature of gas results in an increase in the blade temperature, thereby inducing more…

Materials used in the manufacture of the blades consist of mainly three different elements, namely iron, nickel, and cobalt with chromium which forms one of the major alloying elements, since it gives high resistance to oxidation. Other alloying elements that have been used include most of the metals of the periodic table. Materials working under…

The arrangement shown in Fig. 16.36 has two shafts with two turbines in series. It gives advantage of independent shaft speeds. GAS TURBINE FUELS The various fuels used for gas turbines are as follows:

It is possible to use two turbines in parallel by using a single compressor and a single combustion chamber. The arrangement for such a system is shown in Fig. 16.34. For 1 kg of air through the compressor, a certain fraction x is required to pass through turbine I in order to drive the compressor. Then (1 − x)…

The operating variables for the performance of open cycle gas turbine are as follows: These variables affect the thermal efficiency and the work ratio of the gas turbine. 1 Effect of Pressure Ratio For the simple Brayton cycle, Thermal efficiency,  Work ratio,  The thermal efficiency for various values of γ and rp are given in Table 16.2. The variation of…

Similar to the case of 16.12.6, it can be shown that Example 16.1 Calculate the indicated mean effective pressure and efficiency of a Joule cycle if the temperature at the end of combustion is 2000 K and the temperature and pressure before compression are 350 K and 1 bar, respectively. The pressure ratio is 1.3…

The thermal efficiency of open cycle constant pressure gas turbine can be improved by the following methods: 1 Regeneration In this method, the heat of the exhaust gases is used to heat the air coming out from the compressor, thus reducing the mass of fuel supplied in the combustion chamber. A schematic diagram of such…

The open cycle constant pressure gas turbine plant is shown diagrammatically in Fig. 16.8. The fuel is burned with air coming out from the compressor into the combustion chamber. The products of combustion from the combustion chamber are passed through the turbine and developed the required power. Part of the power developed is used to run…

1 Maximum Pressure Ratio for Maximum Specific Work It is not possible to achieve isentropic compression and expansion in the actual Brayton cycle because of inevitable losses due to friction and turbulence in the compressor and turbine. Therefore, the temperature at the end of compression and expansion are higher than that in an ideal cycle…