How It Works
Heat Generation in Hydraulic Systems
Every hydraulic system generates heat due to inefficiencies. The total heat load must be dissipated to maintain fluid temperature within acceptable limits (typically 40-60C / 104-140F).
Heat Sources
- Pump losses: Mechanical and volumetric inefficiency (typically 10-20% of input power)
- Relief valve flow: Full power converted to heat when oil bypasses
- Pressure drops: Valves, fittings, lines all generate heat
- Motor inefficiency: Mechanical losses in hydraulic motors
- Cylinder friction: Seal and rod friction losses
Heat Load Calculation
Total heat = Input Power - Useful Work Output
Q_heat = P_input x (1 - Overall Efficiency)
Or for specific components:
Q = P x dP / 600 (kW, where P is LPM and dP is bar)
Thermal Balance
At equilibrium: Heat Generated = Heat Dissipated
Heat dissipation occurs through:
- Reservoir surface (natural convection)
- Lines and components (conduction/convection)
- Oil cooler (forced convection)
Heat Load Calculator
Calculate total system heat load from multiple sources and determine cooling requirements.
Pump Parameters
Relief Valve Losses
Valve & Line Losses
Motor/Actuator Efficiency
Reservoir & Ambient
Ready to Calculate
Enter system parameters
Heat Load Analysis
Total Heat Load
--
Pump Inefficiency Heat
--
Relief Valve Heat
--
Valve/Line Heat
--
Average Heat (with duty)
--
System Efficiency
--
Thermal Capacity
Cool
Warm
Hot
Reservoir Natural Dissipation
--
Required Cooler Capacity
--
Est. Temp Rise (no cooler)
--
Typical Heat Values
| Source | Heat as % of Input |
|---|---|
| Pump (85% eff) | 15% |
| Relief valve (bypass) | 100% of bypass power |
| Directional valves | 3-5% |
| Flow controls | 5-15% |
| Lines & fittings | 1-3% |