5 Gas turbine cycles Report A

Pagina 1

Course of Energy Conversion A 2014/2015 Prof. G. Valenti _________________________________________________ 5th project Gas Turbine Cycles  Index: 1. Introduction; 2. Efficiency-Specific work charts; 3. Entropy analysis of the optimized cycles; 4. Effects of TIT variations on efficiency; 5. Effects of polytropic efficiency variations of the turbomachines; 6. Effects of pressure losses variation at silencer/filter housing. 1. Introduction The present project aims at calculating with the aid of the software Turbogas the predicted performance of different gas turbine cycles varying the most significant operating parameters. We will consider the following cycles: 1. Simple cycle gas turbine (SC ) This is the most common and yet simple configuration of the plant; it provides a multistage axial compressor pulled by the axial expander; the first two stages of the turbine are cooled by ait bleedings taken from the high-pressure stages of the compressor. In addition, we have the inlet filter (to avoid the fouling of the machine) and a silencer, which both are responsible of a pressure loss of 0.01% with respect to the ambient pressure. The machines are running at a speed of 3000 RPM due to the matching with the alternator, which needs a frequency of 50 Hz (in order not to use any power electronics). 2. Intercooled gas turbine (IC) This configuration provides an intercooler to decrease the temperature during the compression: let us remember that the best transformation we could imagine (from the point of view of the efficiency) is an isothermal compression, and the use of such a piece of equipment allows us to approximate it in a good manner. At a proximate analysis, the use of the intercooler increases the specific work as the work spent to compress the fluid is strongly…