Automobile radiator as a heat exchanger In automotive engineering, the engine's radiator transfers heat from hot coolant to ambient air by forcing air across finned tubes. Which broad heat-exchanger flow arrangement best describes a typical automobile radiator?

Introduction / Context:
Automobile radiators are compact heat exchangers that remove waste heat from circulating engine coolant. They are built with many small tubes and fins to maximize heat transfer area while keeping pressure drop and mass low. Correctly identifying the flow arrangement helps predict performance, temperature profiles, and effectiveness.

Given Data / Assumptions:

• Hot liquid coolant flows through narrow tubes from inlet tank to outlet tank.
• Ambient air passes through the finned core due to vehicle motion and/or a fan.
• Air and coolant flow directions are essentially perpendicular in the core.

Concept / Approach:
Heat-exchanger arrangements are commonly described as parallel flow (both fluids move in the same main direction), counter flow (fluids move in opposite directions along the same axis), cross flow (fluids move approximately perpendicular), or regenerative (hot and cold streams alternately occupy the same matrix). Radiators are designed with a tube-fin core where the air stream passes across the tubes. The coolant flows longitudinally inside the tubes, while the air stream is driven through the fin passages nearly orthogonal to tube flow. This is a classic cross-flow configuration.

Step-by-Step Solution:

Verification / Alternative check:
Photographs and cutaways of radiators show a tube bundle with louvered fins. The fan or vehicle motion drives air through the core face, not along the tubes. That geometric relationship verifies cross flow. Some designs use multi-pass coolant routing, but the primary relationship remains cross flow.

Why Other Options Are Wrong:

Parallel flow: would require air and coolant to move in the same direction along a shared axis, which is not the case.Counter flow: would require opposite, colinear directions; radiators do not route air that way.Regenerator type: involves periodic storage and release of heat in a matrix, not used in typical radiators.Mixed-flow shell-and-tube: a different construction; automobile radiators are plate-fin/tube-fin cross-flow cores.

Common Pitfalls:
Confusing “crossflow radiator” (a plumbing term about tank positions) with heat-exchanger “cross flow.” Regardless of tank placement, the air path is perpendicular to coolant flow within the core, so the thermodynamic arrangement is cross flow.

Final Answer:

Cross flow type