Lecture 4_Working_Medium_and_Properties_in_Gas_Turbines.pptx

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1. Lecture 4: Working Medium and Properties in Gas Turbines Dinesh Kumar Asst. Prof. Mechanical Engineering 1

2. Introduction The working medium in gas turbines plays a crucial role in determining the efficiency, power output, and overall performance of the engine. Understanding the basic requirements and properties of different working media is essential for selecting the appropriate medium for specific applications. 2

3. Basic Requirements of Working Media in Gas Turbines Thermal Stability: Must remain stable at high temperatures to prevent decomposition or chemical reactions. High Heat Capacity: Desirable to absorb and transport large amounts of thermal energy. Low Viscosity: Reduces friction losses and improves flow characteristics within the turbine. Non-Corrosive Nature: Should not corrode or damage turbine materials. Availability and Cost: Should be readily available and cost-effective. Environmental Impact: Consider emissions and potential pollutants for sustainability. 3

4. Properties of Air Properties: Readily available, non-corrosive, relatively high heat capacity, stable at high temperatures, low viscosity. Advantages: Abundant, cost-effective, environmentally friendly. Disadvantages: Moderate efficiency, requires large volumes for effective heat transfer. 4

5. Properties of Steam Properties: High heat capacity, used in combined cycle gas turbines. Advantages: High efficiency in combined cycles, excellent heat transfer properties. Disadvantages: Corrosive at high temperatures and pressures, requires water treatment, complex handling systems. 5

6. Properties of Hydrogen Properties: Very high specific heat capacity, burns cleanly, producing only water as a byproduct. Advantages: High efficiency, environmentally friendly, abundant in the universe. Disadvantages: Highly flammable and explosive, requires careful handling and storage, expensive production. 6

7. Properties of Helium Properties: Chemically inert, low viscosity, stable at very high temperatures. Advantages: Non-corrosive, high thermal conductivity, suitable for closed-cycle systems. Disadvantages: Rare and expensive, requires airtight systems to prevent leakage. 7

8. Properties of Argon Properties: Chemically inert, high density, advantageous for heat transfer. Advantages: Non-corrosive, stable at high temperatures. Disadvantages: Expensive, lower specific heat capacity compared to other gases. 8

9. Comparison of Different Working Media Property Air Steam Hydrogen Helium Argon Availability High Moderate Moderate Low Moderate Cost Low Moderate High High High Thermal Stability High Moderate High Very High Very High Heat Capacity Moderate High Very High Moderate Low Viscosity Low Moderate Low Very Low Low Corrosiveness Non-Corrosive Corrosive Non-Corrosive Non-Corrosive Non-Corrosive Environmental Impact Low Moderate Very Low Very Low Very Low 9

10. Conclusion Selecting the appropriate working medium for a gas turbine involves balancing various factors such as thermal stability, heat capacity, viscosity, corrosiveness, availability, cost, and environmental impact. Each medium has its advantages and disadvantages, making it suitable for specific applications and operational conditions. Understanding these properties helps optimize gas turbine performance for diverse industrial and power generation needs. 10