Hydraulic Oil Cooler Sizing Calculator

Inputs

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Average pump or circuit flow used for the heat-load screen.
L/min
Working pressure used to estimate hydraulic power.
bar
Hydraulic power out divided by shaft power in. Pump loss becomes heat.
Fraction of useful hydraulic power assumed to return as throttling, valve, actuator or motor losses.
Average fraction of time the entered pressure/flow/load-loss condition is active.
Optional measured or estimated heat from relief bypass, bearings, gearboxes or adjacent equipment.
kW
Multiplier applied to estimated heat load before cooler selection.
Oil flow through the cooler core, used for oil temperature rise.
L/min
Operating oil temperature minus cooling-air inlet temperature.
°C
Cooler catalog heat rejection at the catalog stated oil-air temperature difference.
kW
Oil-air temperature difference used for the entered catalog rating.
°C
Oil density at operating temperature.
kg/m³
Specific heat capacity used for oil temperature rise through the cooler.
kJ/kg-K

Results

Default result
Edit inputs
Design heat load (P_design)
4.094 kW
Pass

Estimated heat load times the sizing margin.

Estimated heat load multiplied by sizing margin.

Also computed

Estimated heat load (P_heat) 3.412 kW

Pump loss heat 1.88 kW plus load-loss heat 2.67 kW, duty-cycle averaged.

Required catalog rating (P_cat,req) 5.459 kW

Catalog rating needed at the entered catalog ETD.

Rating needed at the catalog ETD.

Selected cooler capacity (P_cool) Pass 6 kW

Selected cooler has design margin at the entered operating ETD.

Entered catalog rating scaled to operating ETD.

Cooler utilization (U) Pass 68.24 %

Design heat load divided by selected operating cooler capacity.

Cooler margin (M_cool) 1.906 kW

Positive capacity margin at the entered ETD.

Oil temp rise through cooler (ΔT_oil) Pass 3.132 °C

Estimated heat load divided by oil mass flow and specific heat.

Method notes 3 notes
  • Heat load combines pump inefficiency, an entered fraction of useful hydraulic power that returns as load/valve heat, duty cycle and any additional heat.
  • Cooler capacity is linearly scaled by oil-to-air temperature difference for screening only; use the manufacturer curve for final selection.
  • Catalog ratings depend on oil viscosity, oil flow, air flow, fan speed, fouling, shrouding, altitude, ambient temperature and installation.

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