For efficient operation, what should be the suction pressure in a low-pressure refrigeration system?

The suction pressure in a low-pressure refrigeration system is crucial for maintaining efficient operation and ensuring that the system functions as intended. Ideally, the suction pressure should be maintained within the designed range of the system. This range is determined during the system's design phase and corresponds to the optimal operating conditions for the refrigerant being used.

When the suction pressure is within the designed range, it allows the compressor to draw in the refrigerant effectively, ensuring that the refrigerant is in a gaseous state and at the correct saturation temperature to absorb heat from the evaporator. This optimizes the refrigeration cycle by promoting effective heat transfer and maximizing system efficiency.

Other options may represent scenarios that could lead to suboptimal performance. For instance, a suction pressure equal to atmospheric pressure may result in insufficient refrigerant evaporation, while being higher than ambient temperature could cause the refrigerant to not function correctly within the system, leading to poor heat absorption. A suction pressure lower than 0 psig would indicate a vacuum situation, which may also not be suitable for proper system operation unless specifically designed for such pressure. Thus, maintaining the suction pressure within the designed range is essential for the efficient operation of a low-pressure refrigeration system.