What effect does air noncondensible gas have on suction pressure in an ammonia system?

In an ammonia refrigeration system, the presence of noncondensible gases (such as air) has a significant impact on suction pressure. Noncondensible gases do not condense like ammonia; therefore, they occupy space in the system that should be filled by the refrigerant. As a result, these gases effectively reduce the amount of ammonia vapor in the evaporator, which leads to lower suction pressure.

When noncondensible gases infiltrate the system, they create a barrier that hinders the proper function of the refrigeration cycle. This reduction in the density of the ammonia vapor in the evaporator means that the suction pressure must decrease to maintain the same temperature and enthalpy of the refrigerant. Thus, the overall effect is a lowering of suction pressure, which can lead to reduced system efficiency, increased energy consumption, and potential operational issues due to insufficient refrigeration capacity.

In this context, the correct identification of the effects of noncondensible gases on suction pressure is essential for understanding the operational integrity of ammonia systems and ensuring their efficient performance.