I. Basic Structural Zoning (Double-Circuit Isolated Heat Exchange for Shell-and-Tube Design)
The equipment consists of two fully isolated fluid passages, namely the shell side and tube side, with zero cross-mixing of media:
- Shell Side (Inner space of the cylinder) – Circulation path for high-temperature hydraulic oilHot oil discharged from the extruder hydraulic station enters the green cylinder via large flange ports at both ends, and flows around the outer surface of copper tubes.
- Tube Side (Internal red copper heat exchange tube bundle) – Circulation path for circulating cooling waterCold water flows in and out through two small threaded connectors on the side of the cylinder, circulating continuously inside thin copper tubes.
- Heat transfer medium: High thermal conductivity red copper tube walls act as the medium for heat transfer. Hydraulic oil and cooling water are completely separated by metal tube walls to prevent cross-leakage between the two fluids.
II. Full Heat Exchange Process
Source of Heat Generation
Continuous high-pressure operation of the extruder hydraulic pumps and hydraulic motors generates heat through friction of hydraulic oil, pushing the oil temperature above 60 °C under normal operation. High oil temperature reduces oil viscosity, which further causes unstable system pressure and premature aging of oil seals, making cooling an essential requirement.
Heat Conduction Mechanism
High-temperature hydraulic oil wraps the outer walls of copper tubes, and heat is rapidly conducted through red copper tube walls to the low-temperature cooling water flowing inside the tubes.
- Hot hydraulic oil releases heat, cools down, and flows back to the hydraulic oil tank for recirculation through the oil outlet.
- Cooling water absorbs heat, warms up, exits the cooler, and flows back to the cooling tower/water tank for heat dissipation before being recycled for repeated use.
Optimized Fluid Flow Direction (With Baffle Plates)
Baffle plates are installed inside the cylinder, forcing hydraulic oil to flow in an S-shaped circuitous path. This extends the contact duration between hydraulic oil and copper tubes, greatly improving heat exchange efficiency and preventing hot oil from short-circuiting and flowing out rapidly without sufficient cooling.
III. Temperature Control Logic Matched with Extruders
The cooler continuously removes heat from the hydraulic system to stabilize the oil temperature within the optimal operating range of 35~45 °C.
- Constant oil temperature maintains hydraulic oil viscosity at the standard value, stabilizing screw feeding pressure and cutter rotational speed, and producing uniform extruded pellet products.
- Long-term low-temperature operation slows the oxidation of hydraulic oil and reduces wear on hydraulic pumps and sealing components, minimizing equipment downtime and malfunctions.