Which physical law explains that energy within a closed system remains constant?

The First Law of Thermodynamics is pivotal in understanding energy conservation within a closed system. It states that energy cannot be created or destroyed; rather, it can only be transformed from one form to another. In a refrigeration context, this law governs how energy is transferred as heat during the refrigeration cycle – whether the system is absorbing heat in the evaporator or releasing heat in the condenser.

For example, in a refrigeration system, the work done by the compressor converts electrical energy into mechanical energy, which is then transformed into thermal energy that gets absorbed and rejected, adhering to the principle of conservation of energy. This fundamental understanding helps refrigeration operators ensure efficient and effective system performance.

The other laws, while also important, serve different purposes. The Second Law of Thermodynamics deals with the directionality of energy transfer and the increase of entropy in a system, while the Third Law relates to absolute zero temperature and the behavior of systems as they approach it. The Heat Transfer Law, more of a principle than a discrete law like the others, refers to how heat moves but does not serve to describe energy conservation itself.