Match each mechanical system or scenario with the correct description of its convective heat transfer process.
- Coolant is pumped through the internal water jacket of a running engine.Forced convection transferring thermal energy from a solid to a liquid.
- Air is pushed by a blower across the hot external fins of a vehicle's radiator.Forced convection transferring thermal energy from a solid to a gas.
- Hot combustion gases travel up and out of a tall, unpowered industrial smokestack.Natural convection driven by the reduced density of a heated gas.
- A motorized ceiling fan is reversed in winter to push warm air downward.Forced convection used to overcome the natural buoyancy of a heated gas.
Answer
Engine coolant matches forced convection into a liquid; the radiator blower matches forced convection into a gas; the smokestack matches natural convection of a heated gas; and the reversed ceiling fan matches forced convection overcoming gas buoyancy.
Each mechanical application relies on a specific interaction between a solid and a fluid, or manipulates fluid flow using either mechanical force or natural buoyancy. The pump moves a liquid medium, the blower moves a gaseous medium across solid fins, the smokestack utilizes density differences, and the ceiling fan directly opposes thermal rising.
Step-by-Step Solution
Key Concept
Convection is 'forced' when a mechanical device (pump, fan) moves the fluid, and 'natural' when temperature-induced density changes cause the fluid to rise or fall.