Patent ID: 7406837

Claim:
An ammonia/CO 2 refrigeration system comprising apparatuses working on an ammonia refrigerating cycle, a brine cooler for cooling and condensing CO 2 by utilizing the latent heat of vaporization of the ammonia, and a liquid pump provided in a supply line for supplying the cooled and liquefied CO 2 to a refrigeration load side heat exchanger (cooler), wherein are provided; a receiver for receiving CO 2 brine cooled in said brine cooler, a liquid pump composed to be a variable-discharge type forced circulating pump, which corresponds to said liquid pump for supplying the cooled and liquefied CO 2 , a riser pipe located between said liquid pump and a heat exchanger of refrigeration load side, a communication pipe for connecting the top part of the riser pipe to the CO 2 gas layer in said liquid receiver; wherein discharge pressure (of forced circulation) is determined so that CO 2 recovered from the outlet of cooler of refrigeration load side returns to said brine cooler or said liquid receiver in a liquid or gas/liquid mixed state (incompletely evaporated state), and wherein the top part of the riser pipe runs along a height position equal to or higher than the maximum liquid level of CO 2 reserved in the liquid receiver.