CFD Simulation of an EGR Cooler for Exhaust Gas Thermal Management

Challenge

An EGR cooler must bring hot exhaust gas down to a target temperature within tight pressure-drop limits. Uneven gas or coolant distribution creates cold spots, which reduce effectiveness, and hot spots, which raise the risk of local coolant boiling and thermal fatigue. The low-velocity gas regions that result are also where soot fouling tends to build up.

Approach

A conjugate heat transfer model resolved the exhaust-gas flow, coolant flow and wall conduction together. The cooler was assessed for gas outlet temperature, gas-side pressure drop, flow uniformity across the passages, and coolant-side wall temperatures in high-heat-flux regions.

Key Findings

• Inlet header geometry caused uneven gas distribution across the passages, which left some passages underused and reduced overall cooling effectiveness.
• The highest wall temperatures and heat fluxes occurred near the gas inlet. Coolant velocity there was critical for avoiding local boiling.
• Low-velocity coolant zones, particularly near the corners and baffles, were identified as hotspot risks.
• Improving inlet flow distribution was the most effective way to raise effectiveness without a proportional increase in pressure drop.

Deliverables

Gas and coolant velocity and temperature fields, wall temperature and heat flux maps, pressure-drop assessment, and design recommendations for header and passage distribution.