My professor told that cars usually use fluid cooling because...
Fluid cooling is more stable, because you have the added thermal mass of a couple gallons of fluid. It is easier to regulate temperature, through the use of the thermostat. It also reduces problems with hotspots, and multi-cylinder engines can be made much more compact.
Really, the question of efficiency is practically not even a concern- in modern times it is typically not until you have a racing engine, that you begin to have cooling problems. The real concerns are reliability and added complexity of the cooling system. The biggest advantages are improved longevity and performance of your engine.
It is true that an old car going uphill on a roasty day with the A/C on may overheat, but even then it is often a problem with poor maintenance or the wrong mix of coolant. (When your coolant boils, your cooling system cannot cool the engine effectively. Vapor has far, far inferior heat conduction properties. This is one of the reasons why the system is typically pressurized)
Fluid cooling is more stable, because you have the added thermal mass of a couple gallons of fluid. It is easier to regulate temperature, through the use of the thermostat. It also reduces problems with hotspots, and multi-cylinder engines can be made much more compact.
Really, the question of efficiency is practically not even a concern- in modern times it is typically not until you have a racing engine, that you begin to have cooling problems. The real concerns are reliability and added complexity of the cooling system. The biggest advantages are improved longevity and performance of your engine.
It is true that an old car going uphill on a roasty day with the A/C on may overheat, but even then it is often a problem with poor maintenance or the wrong mix of coolant. (When your coolant boils, your cooling system cannot cool the engine effectively. Vapor has far, far inferior heat conduction properties. This is one of the reasons why the system is typically pressurized)