Which type of system does not rely on mechanical means to increase heat transfer?

The statement that passive systems do not rely on mechanical means to increase heat transfer is accurate because passive systems function by utilizing natural physical processes to enhance heat transfer. They often make use of thermal insulation, building orientation, and material selection to facilitate efficient thermal management without the need for active mechanical components like fans or pumps.

In passive systems, methods such as natural convection and radiation are employed to transfer heat, taking advantage of the environment and design features. For instance, a building designed to maximize natural airflow or solar gain can achieve effective heating and cooling without any mechanical assistance.

Active systems, in contrast, use mechanical devices to enhance heat transfer processes, such as fans in forced convection systems. Natural systems typically describe processes that occur without human intervention, while forced convection systems specifically involve mechanical means to move fluids, thus enhancing heat transfer through increased airflow.