When does the majority of heat used in the gas defrost get delivered to the evaporator?

The majority of heat used in the gas defrost is delivered to the evaporator when the refrigerant gas transitions back into a liquid state. This process involves the refrigerant absorbing heat from the surrounding environment, which allows it to change from a gas to a liquid. During this phase change, a significant amount of latent heat is released, which contributes to the effective heating required for defrosting.

When refrigerant changes state, it absorbs or releases heat without a change in temperature, meaning that the energy involved in this process is substantial. This is particularly relevant in systems designed for gas defrosting, where the efficiency and effectiveness of the heat transfer depend on the phase transition of the refrigerant. By maximizing heat transfer during this state change, the system can effectively remove frost or ice buildup, ensuring optimal performance of the evaporator.

In contrast, options referencing the temperature and pressure of the gas coming into the evaporator focus on the properties of the refrigerant rather than the mechanism by which heat is delivered during defrosting. Notice that while high temperature and pressure can enhance performance, they don’t directly pertain to the critical phase change process that releases the majority of heat necessary for defrosting.