In order to keep the operating temperature of oil-hydraulic systems as constant as possible, it is necessary to use an oil cooler to dissipate any heat losses that cannot escape through thermal radiation. The size and type of the oil cooler will depend on the following:
- size of the losses,
- permissible oil temperature,
- permissible coolant temperature,
- permissible pressure loss.
Two cooler designs are available:
Water-cooled oil cooler:
The oil flow passes through pipes with turbulence inserts to increase heat transfer. The fluid in these pipes flows in the opposite direction to the cooling water (Figure O 4).
Figure O 4: Water-cooled oil cooler
Air-cooled oil cooler:
A fan passes a flow of cooling air through the oil cooler (Figure O 5). This form is used in stationary hydraulic systems, and mainly only when low cooling capacities are involved.
Air-cooled oil cooler