Gas Turbine Engineering - Webinar 1 Summary
Course Overview
The course covers gas turbines, using Moodle for resources. Contact learning support for admin issues, the speaker for technical.
Six webinars with quizzes, two assignments requiring citations. Extensions available. 70% attendance or webinar summaries needed for certificate.
Three quiz attempts allowed. 12 modules cover thermodynamics, turbine principles, components, and maintenance.
RemoteLab for practical exercises. Pass mark is 60%. EIT provides certificate.
Focus on practical skills, latest practices, and thermodynamic principles.
Module 1 & 2: Introduction to Gas Turbines and Thermodynamics
Gas turbines have evolved since 1903, now more powerful.
Key requirements: easy installation/maintenance, reliability, efficiency, environmental compliance, fuel flexibility.
Prime movers convert energy into mechanical energy.
Gas turbines are compact, quick starting, used for electricity, heat, or steam.
Turbojet engines were the first gas turbine engines (intake, compression, combustion, exhaust).
Efficiency depends on engine pressure ratio and firing temperature.
Applications: aircraft, power generation, mechanical drives, marine.
Types: turbojet, turbofan, turboprop, turbo shaft.
Power generation turbines range from small to large.
Turbojets generate thrust from exhaust gases.
Turbofans use a ducted fan.
Turboprops use a prop.
Turbo shafts extract power from exhaust.
Afterburning turbofans increase thrust but are inefficient.
Turbines by power generation: small, medium, large frame.
Ground-based turbines: frame type, aircraft derivative, small gas, microturbines.
Frame type: heavy duty, high efficiency, combined cycle (up to 50%).
Aeroderivative: lighter, compact, from air use.
Turbine Types and Applications
Aircraft derivative turbines: variable speed, low weight, high efficiency, fast maintenance/start-up. Limited power, fuel, short inspections.
Industrial turbines: reliability, availability, high inertia. Fixed speed, heavy, large, lower efficiency, long downtime, slow start-up.
Micro gas turbines generate less than five megawatts.
Gas Turbine Components
Compressor: pressurized air to the combustion chamber.
Combustors: combustion occurs.
Expander (Turbine): exhaust gases are expanded to do work.
Regenerators: utilize exhaust gases to improve turbine efficiency.
Other Components: Exhaust nozzles, igniters, fuel atomizers.
Gas Generator (Core): Compressor, burner, and turbine.
Ideal Gas Conditions
Working fluid is a perfect gas with constant specific heats.
Expansion and compression processes are isentropic.
No pressure loss in combustor, heat exchanger, intercooler, and ducting.
No variation in mass flow.
Heat transfer in heat exchangers is 100%.
Isentropic Process
Adiabatic process with no heat or matter transfer.
Work transfers are frictionless, and entropy remains constant.
Second law of thermodynamics states total entropy either increases or remains constant.
Brayton Cycle
Thermodynamic cycle used in heat engines, gas turbines, and jet engines.
Compression: Ambient air is compressed.
Combustion: Fuel is added at constant pressure.
Expansion: Gases expand to drive the turbine.
Exhaust: Heat is rejected.
Components: Two isobaric and two isentropic processes.
Variations: Simple heat exchange cycle, intercooled cycle, reheat cycle, combined intercooled and reheat cycle.
Actual Gas Turbine Cycles
Take into account compressor, combustor, and turbine efficiency and pressure losses.
Intercooled cycle: Increased network done without changing turbine work output.
Reheat cycle: Expansion occurs in two turbines with reheating in between.
Combined intercooler and reheat cycle: Combines advantages of both cycles but may not increase efficiency compared to a simple cycle.
Cogeneration
Uses waste heat for generating steam, heating water, or heating air.
Common in mineral refineries with high steam demand.
Allows selling electricity back to the supplier during peak times.
The EU currently generates 11% of its electricity using cogeneration.