With a schematic diagram, explain working of a Stirling engine ( Parabolic Dish–Stirling Engine System)

Parabolic Dish–Stirling Engine System

The parabolic dish–Stirling engine system is an advanced solar energy conversion technology that utilizes a parabolic dish concentrator to harness solar energy and convert it into electricity through a Stirling engine.

Major Components

1. Solar Dish Concentrator:
   1. Collects and focuses sunlight onto a thermal receiver.
   1. Heat Transfer Fluid: A fluid (like oil or water) circulates through the system, carrying heat to the power conversion unit.
2. Power Conversion Unit:
   1. Thermal Receiver:
      1. Absorbs concentrated solar energy and converts it to heat.
      1. Often composed of tubes where a cooling fluid flows, or heat pipes that use the principles of boiling and condensing to transfer heat.
   1. Stirling Engine:
      1. Utilizes the heated working fluid (often hydrogen or helium) to produce mechanical power.
      1. The engine includes components such as:
         1. A receiver for absorbing sunlight and heating the working fluid.
         1. An alternator that converts mechanical work into electrical energy.
         1. A waste-heat exhaust system to release excess heat.
         1. A control system to optimize engine performance based on available solar energy.
3. Tracking System:
   1. A computer system adjusts the dish’s orientation, ensuring concentrated sunlight is focused onto the receiver for maximum energy capture.

Working of the Stirling Engine

 Stirling and Brayton Cycles:

1. Sunlight Concentration: An array of mirrors focuses sunlight onto the thermal receiver, heating the working fluid to temperatures around 750°C.
2. Energy Conversion: This high-temperature fluid is used in a Stirling or Brayton cycle to produce mechanical power, which is then converted into electricity.

• Brayton Cycle: Involves heating compressed air with concentrated sunlight, which reduces the need for fuel combustion.
• Energy Generation: The hot compressed air expands through a turbine, creating rotational energy, which is converted to electricity by an alternator.
• Efficiency: A recuperator captures waste heat from the turbine to preheat the compressed air, making the process more efficient.

Schematic of solar electric generation