Identify the fluid dynamics at work by pairing each mechanical component or structural design with its correct convection mechanism.
- Tall exhaust chimney above a furnaceDrives an upward draft due to the reduced density of heated gases.
- Motorized ceiling fan operating in reverseMechanically disrupts thermal stratification by pushing accumulated warm air downward.
- Passive solar water heater with an elevated storage tankEstablishes a passive liquid circulation loop based on fluid density differences.
- Belt-driven centrifugal pump in an engine cooling loopMechanically circulates liquid coolant to rapidly transfer heat away from a source.
Answer
The chimney relies on natural convection of gases; the ceiling fan uses forced convection of gases; the solar water heater uses natural convection of liquids; and the centrifugal pump uses forced convection of liquids.
Convection transfers heat through the macroscopic movement of fluids (gases or liquids). This movement can be natural, where heated fluid becomes less dense and rises, or forced, where a mechanical device moves the fluid. The correct pairs perfectly map each mechanical system to its specific fluid state and its specific driving force.
Step-by-Step Solution
Key Concept
Convection occurs in both gases and liquids and can be driven naturally by density differences (buoyancy) or forced mechanically by fans and pumps.