Final answer:
The medium used to vaporize refrigerant and increase its temperature in an absorption system is steam, contrasting with the condenser which converts gas back to liquid in the refrigeration cycle.
Step-by-step explanation:
In an absorption refrigeration system, the medium that is normally used to vaporize refrigerant and increase its temperature is steam. The evaporator in an air conditioning system plays a crucial role by converting the liquid refrigerant into gas. This is part of an endothermic process, which requires the absorption of heat, similar to how the body uses the evaporation of water from the skin to maintain a constant temperature. In contrast, the condenser is the component that converts the gaseous refrigerant back into a liquid. This is a crucial aspect of the refrigeration cycle, ensuring the continuous transfer of heat from the interior to the exterior environment.