What is used as the cooling medium in the oil heat exchanger?

The correct answer is that water from the cooling system is used as the cooling medium in the oil heat exchanger. In gas turbine systems, maintaining optimal temperatures for lubricating oil and other fluids is crucial for system performance and reliability. The oil heat exchanger often utilizes water to absorb excess heat from the oil, allowing the oil to remain at an appropriate operating temperature.

Using air from the atmosphere is less effective in transferring heat compared to liquids like water, which have higher thermal conductivity and heat capacity. Additionally, 2190 oil from the MRG (Main Reduction Gear) and fuel oil from the storage tank would not be suitable as cooling mediums for the oil heat exchanger, as these would not effectively transfer heat in the same way that water does. Therefore, water from the cooling system is the most appropriate and effective choice for maintaining proper oil temperatures within the gas turbine system.