Gas Turbine Effect on Refrigeration Cycle

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Thread Starter

Sadiq

If we have a refrigerant compressor (which is a part of refrigerant cycle) driven by gas turbine. How the efficiency of gas turbine will effect on the performance of refrigerant cycle?
 
Sadiq,

If I understand the question correctly, the efficiency of the gas turbine will not have an effect on the performance of the refrigeration cycle--except that if the gas turbine heat rate decreases (dirty axial compressor; dirty inlet air filters; degraded hot gas path components) it will take more fuel to produce the same work, or, less work will be produced for the same fuel. The work is the torque being supplied to the refrigeration compressor, and the compressor condition (clearances; seals; etc.) determine how well (efficiency) the compressor converts the torque to pressure/flow.

So, one has to consider what the gas turbine is providing to the refrigeration compressor--and that's just torque (if I understand the question correctly). The production of torque is a function of gas turbine condition. The refrigeration compressor converts the torque to pressure/flow, and the condition of the refrigeration compressor determines how well it performs that conversion (also called efficiency, I would think).

To my mind, gas turbine efficiency--and refrigeration compressor efficiency--are both a function of machine condition. The gas turbine produces torque (at some heat rate), and the refrigeration compressor converts that torque to refrigerant pressure/flow. And, it takes fuel to produce the torque to develop the pressure/flow. The efficiency (heat rate) of the gas turbine isn't going to impact the refrigeration compressor's ability to develop pressure/flow--but it does have an impact on the overall cycle efficiency (how much fuel is required to produce pressure/flow). Refrigeration compressor condition affects its ability to convert the torque it receives from the gas turbine to pressure/flow--and that doesn't have anything to do with gas turbine efficiency.

If you're having some problem with the refrigeration cycle it's probably not being caused by the gas turbine--unless the gas turbine condition is so degraded that it can't produce sufficient torque to drive the refrigeration compressor to produce desired (or required) refrigerant pressure/flow. It's more likely there is some problem with the refrigeration compressor or the valves associated with the compressor (bypass; suction; discharge). If the refrigeration compressor isn't able to convert the torque being supplied to pressure/flow that's a more likely cause of cycle problems.

Hope this helps!
 
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