Question

A direct expansion (bare) coil evaporator is used to maintain a meat storage space at 28 to 30° F. The last coil has no frost. It can be said that this system is

A) condition is acceptable to maintain a high plant efficiency
B) is a direct indication of air in the system
C) indicates moisture in the refrigerant
D) is a direct indication that the coil is being starved

Answer 1

The absence of frost on the last coil of a direct expansion (bare) coil evaporator in a meat storage refrigeration system indicates that the coil may be starved of refrigerant, implying potential inefficiency in the system.

Step-by-step explanation:

In a refrigeration system, the absence of frost on the last coil of a direct expansion (bare) coil evaporator, which is used to maintain the temperature of a meat storage space, could indicate several conditions.

One such condition is the possibility of the coil being starved of refrigerant, as frost formation is associated with the refrigeration cycle where the evaporator extracts heat from the air, causing the moisture to freeze. If the last coil has no frost while the goal is to maintain a temperature within 28 to 30°F, it suggests that there is not enough refrigerant reaching that section of the coil to absorb the necessary heat and form frost.

This could be due to various reasons, such as a blockage in the refrigerant lines, improper refrigerant charge, or a faulty expansion valve, leading to suboptimal performance and potential inefficiency of the system.