What does heat transfer in refrigeration primarily depend on?

Heat transfer in refrigeration is fundamentally driven by the temperature difference between two systems or substances. When there is a temperature gradient, heat flows naturally from the higher temperature area to the lower temperature area until thermal equilibrium is reached. This principle is essential in refrigeration systems, as the objective is to remove heat from one space (the refrigerated area) and transfer it to another area (typically the environment), achieving a cooling effect.

In propane systems, for instance, the refrigerant absorbs heat from the surroundings as it evaporates in the evaporator coil, which cooling the space. This process relies on the temperature difference between the refrigerant and the items being cooled. Without this temperature differential, the refrigeration cycle would not effectively remove heat, and the system wouldn't function as intended. Therefore, the correct option underscores the critical role that temperature difference plays in facilitating heat transfer within refrigeration systems.