Advanced HeatExchanger Diffusion Design

1
Advanced Heat-Exchanger Diffusion Design
David Lazzara, Advisor Mark Drela

• Problem Application
• Cogeneration Power Plants drive Steam Turbines
  using Gas Turbine Exhaust
• Large cross-sectional area Heat Exchangers and
  Diffusion Tunnels required to extract Energy from
  Turbine Exhaust
• Design Solution
• Diffusing blade rows with minimal geometry
  (solidity, etc.)
• Airfoil Cooling reduces Momentum Defect and
  increases Diffusion while limiting Viscous losses
• Utilize MISES CFD code by Prof. Drela

2
Advanced Heat-Exchanger Diffusion Design
David Lazzara, Advisor Mark Drela

• Design Objectives
• Minimize Viscous Losses
• Tradeoff between solidity and Re
• Tradeoff between chord and turning angle
• Maximize Heat Transfer
• Boundary Layer provides convective Heat Flux
• Momentum Defect inversely proportional to
• Heat Flux
• Maximize Diffusion
• Use minimum number of stages
• Cooling permits greater Pressure Ratio per
• stage