Fundamental Insulation 1 Piping Course Practice Exam

Choose the correct definition of CONVECTION as used in the insulation industry. It is one of the three primary mechanisms of heat transfer that is defined as

The transfer of heat through a solid material

The movement of heat within a fluid due to density differences

The emission of radiation from a hot body

The transfer of heat from a region of higher temperature to a region of lower temperature by the displacement of cooler molecules by warmer molecules

Convection is heat transfer through the bulk motion of a fluid caused by density differences. When a portion of the fluid is heated, it becomes less dense and tends to rise, while cooler, denser fluid sinks to take its place. This circulation carries thermal energy from the hotter region to the cooler region. In insulation work, this movement of air or other fluids in gaps or channels is what transfers heat, so describing convection as the transfer from hot to cold by the displacement of cooler fluid by warmer fluid captures the dynamic, bulk-flow nature of this mechanism.

The other descriptions point to the other two mechanisms: heat transfer through a solid by direct contact is conduction, and heat transfer by electromagnetic waves is radiation.