Ice making refrigeration system

In an ice making refrigerating system adapted to be cycled alternately through a freezing phase and an ice harvesting phase and including a compressor, a condenser and an evaporator having a closed refrigerant chamber with an ice forming surface thereon for applying a substance to be frozen during the freezing phase,

• (a) an accumulator tank above and externally of said refrigerant chamber,
• (b) valve means communicating said accumulator tank with said refrigerant chamber and disposed to deliver liquid refrigerant by gravity flow to said refrigerant chamber during the freezing phase,
• (c) a suction conduit communicating the upper portion of said accumulator tank with the suction side of said compressor for separating liquid from vapor and returning vaporized refrigerant to said compressor,
• (d) a vapor-liquid return conduit communicating an upper portion of said refrigerant chamber with said accumulator tank and disposed to convey vaporized refrigerant and liquid refrigerant from said refrigerant chamber to said accumulator tank,
• (e) conduit means communicating the discharge side of said compressor with said condenser,
• (f) conduit means communicating the liquid side of said condenser with said vapor-liquid return conduit downstream of said refrigerant chamber so that high pressure makeup liquid replaces the liquid evaporated in the referigeration process and is delivered from the condenser to said vapor-liquid return conduit in the general direction of flow of refrigerant therethrough to form a mixture of said liquid delivered from the condenser and said vaporized refrigerant and liquid refrigerant delivered from said refrigerant chamber and to aid in conveying said mixture toward said accumulator tank,
• (g) valved means for conveying hot gaseous refrigerant under pressure from the discharge side of said compressor to said refrigerant chamber during the harvesting phase to warm said ice forming surface and displace refrigerant from said refrigerant chamber to said accumulator tank;
• and
• (h) control means in said vapor-liquid return conduit downstream of the point said conduit means communicates the liquid side of said condenser with said vapor-liquid return conduit for restricting flow through said vapor-liquid return conduit during the harvesting phase to maintain a predetermined pressure in said vapor-liquid return conduit and allow liquid to pass from said refrigerant chamber to said accumulator tank when a predetermined pressure is reached in said vapor-liquid return conduit.