Which pressure is often compared with superheat in the design cycle?

In the context of refrigeration and air conditioning systems, superheat refers to the temperature of a vapor above its saturation temperature. It is critical for ensuring that the vapor entering the compressor is completely in the gaseous state, thereby preventing liquid from entering the compressor which could potentially damage it.

Suction pressure is the correct comparison when discussing superheat because it refers to the pressure of the refrigerant vapor before it enters the compressor, which is directly related to the vapor's saturation temperature. To determine the amount of superheat, technicians measure the temperature of the refrigerant in the suction line and compare it to the corresponding saturation temperature at the suction pressure. This helps in assessing the efficiency and performance of the refrigeration cycle.

The other options do not serve the same comparative function in this context. Discharge pressure pertains to the pressure of the refrigerant vapor after it has been compressed, while atmospheric pressure is the pressure exerted by the weight of the atmosphere and does not directly relate to the refrigerant's superheat. Vapor pressure could be a point of reference in certain cases, but it is the suction pressure that aligns closely with the concept of superheat in practical applications.