Low Charge Ammonia systems designed as Direct Expansion

摘要

This paper describes the key processes in Ammonia DX refrigeration system controlled by Vapor QualitySensors.Until recently refrigeration systems with a low energy consumption have been synonymous with liquidoverfeed systems with a large refrigeration charge. Direct expansion systems using superheat control havebeen an inefficient alternative. Now new technology, called Vapor Quality Control, makes direct expansionsystems more efficient than liquid overfeed systems and at the same time having the advantage of a low charge.It is now possible to measure and control the phase of refrigerant on all types of evaporators. The two-phaseflow pattern highly depends on the evaporator design and load. By controlling the supply of refrigerant in anintelligent way, you can minimize pressure loss in wet suction lines and riser pipes and with even liquiddistribution it is possible to ensure a uniform and homogeneous load on every evaporator section with a verysmall pressure variation/drop compared to a normal Super Heat controlled system.