What Is The Working Principle Of Hydro Generator Bearing Oil Cooler?

The working principle of a hydro generator bearing oil cooler is based on the principle of heat exchange.
Inside the cooler, there are usually two fluids flowing, one is the bearing oil to be cooled and the other is the cooling medium (usually water) used to carry away the heat.
The bearing oil flows inside the cooler's pipework, which is usually made of materials with good thermal conductivity, such as copper or stainless steel. The cooling water, on the other hand, flows through the space outside the pipes or around them.
Since the temperature of the bearing oil is higher than that of the cooling water, heat is transferred from the bearing oil to the cooling water through the pipe walls.

Specifically, heat transfer occurs in three main ways:
Thermal conduction: Heat is transferred from the high temperature bearing oil side to the low temperature cooling water side through the solid material of the pipe wall.
Thermal convection: Heat is transferred from the high temperature region to the low temperature region by the movement and mixing of fluids during the flow of bearing oil and cooling water.
Thermal radiation: Although the role of radiant heat transfer is relatively small in this case, a small amount of heat is still transferred by radiation in the form of electromagnetic waves.

After the heat exchange, the temperature of the bearing oil decreases while the temperature of the cooling water increases. The cooled bearing oil returns to the hydro generator bearings to continue to play the role of lubrication and cooling, while the warmed cooling water is discharged from the cooler, after the external cooling equipment to cool down and recycle again.

As an example, suppose a hydro generator is running, the initial temperature of the bearing oil is 70℃, after the heat exchange between the cooler and 20℃ cooling water, the temperature of the bearing oil is lowered to 50℃, which ensures the normal working temperature of the bearings, and avoids wear and failure of the bearings due to the high temperature of the oil.