Final answer:
Factors like friction, irreversible processes, and dissipative processes in equipment reduce a heat engine's efficiency by converting work output back into heat, making it impossible to achieve ideal Carnot engine efficiency due to physical laws.
Step-by-step explanation:
The factors that reduce the efficiency of a heat engine from its ideal value include friction, irreversible processes, and dissipative processes in peripheral equipment such as electrical transformers or car transmissions. These factors lead to some of the engine's work output being converted back into heat transfer, thereby lowering the actual efficiency. The actual efficiency of a heat engine can never match that of an ideal Carnot engine due to these real-world constraints, which are bound by the second law of thermodynamics.
Additionally, for heat pumps, the efficiency can be impeded by processes that convert part of the work input back into heat transfer to the cold reservoir. In the case of modern engines and power stations, inefficiencies are not solely a result of design or materials but are also determined by fundamental physical laws governing heat transfer and work.