Refrigeration Applications: Liquid Recirculation

Liquid recirculation is the most practical, economical and efficient method of supplying refrigerant to the many evaporators found in industrial refrigeration plants. They are used for all temperature levels, from 40°F to -60°F (4.4°C to -51°C), but are generally associated with R-717 (ammonia) systems since ammonia is the predominant industrial refrigerant. Recirculation systems use liquid refrigerant pumps or hot-gas pressurized dump vessels to deliver liquid refrigerant at evaporator temperature to the evaporators. The elevated pressure is elevated to 20 to 30 psi (138 to 207 kPa) above the evaporator pressure. This delivery pressure is reduced at each evaporator through manual hand expansion valves, known as "balance valves."