How does exhaust temperature impact the backpressure on a turbine and overall performance?

How does exhaust temperature impact the backpressure on a turbine and overall performance?

• A. Exhaust temperature has no effect on backpressure.
• B. Higher exhaust temperature always reduces backpressure.
• C. Lower exhaust temperature increases electrical output.
• D. Higher exhaust temperature can increase backpressure, reducing net work; proper exhaust design reduces backpressure and matches generator.

Answer: (D)

Backpressure in the exhaust path is the pressure the turbine must work against as it expels hot gas. The turbine produces useful work by expanding gas from a higher to a lower pressure; if the exhaust system adds resistance, that usable pressure drop is reduced, so net work and power drop. Higher exhaust temperature means the gas carries more energy and tends to flow more vigorously through the exhaust path, increasing friction and other losses in ducts and components. Those losses show up as greater backpressure, which cuts into the turbine’s effective pressure drop and reduces the energy delivered to the generator. A well-designed exhaust system minimizes these losses and is matched to the generator so the turbine operates with an optimal pressure ratio, maximizing net work.

Backpressure in the exhaust path is the pressure the turbine must work against as it expels hot gas. The turbine produces useful work by expanding gas from a higher to a lower pressure; if the exhaust system adds resistance, that usable pressure drop is reduced, so net work and power drop. Higher exhaust temperature means the gas carries more energy and tends to flow more vigorously through the exhaust path, increasing friction and other losses in ducts and components. Those losses show up as greater backpressure, which cuts into the turbine’s effective pressure drop and reduces the energy delivered to the generator. A well-designed exhaust system minimizes these losses and is matched to the generator so the turbine operates with an optimal pressure ratio, maximizing net work.