A holding chamber may be supplied from a storage vessel system with a cryogen, such as liquid CO.sub.2, or it may itself be large enough to take the place of a separate storage vessel. The temperature within the holding chamber is reduced to the triple point or below to form a refrigeration reservoir of solid cryogen, as by removing vapor from the chamber to cause evaporation or by employing mechanical refrigeration. The stored cooling power of the reservoir is later employed to meet a large or a periodic refrigeration demand and is thereafter replenished over a number of hours, preferably during a period of non-peak electric demand. This storage principle can be incorporated into a variety of different refrigeration systems. For example, a CO.sub.2 storage system may be used to produce and store solid CO.sub.2 during a period of low demand upon a coupled mechanical refrigeration system; thereafter, the solid CO.sub.2 is used to supplement the mechanical system during a high-demand period, thereby increasing the effective refrigeration capacity of the mechanical system.
A refrigeration system comprises a mixing tank for a slurry of solid particles in a liquid, said mixing tank having first and second inlets and an outlet. A sublimator has a bottom inlet, a top outlet and several internal paths connecting the inlet and the outlet, said internal paths having no descending parts. A first conduit connects the outlet of the mixing tank to the bottom inlet of the sublimator via a pump, there being no descending parts between the pump and the inlet of the sublimator. A separator has an inlet and top and bottom outlets. A second conduit connects the outlet of the sublimator to the inlet of the separator, the bottom outlet of the separator being connected to the first inlet of the mixing tank. A compressor has an inlet and an outlet, and conduits connect the top outlet of the mixing tank to the inlet of the compressor and the outlet of the compressor to the second inlet of the mixing tank.
A method and apparatus for maintaining a liquid-frozen solid slush mixture in a vessel at a desired total slush mixture and desired solids content during conditions under which the solids in the slush mixture in the vessel are melting. The method comprises introducing fresh slush mixture to the vessel, while removing liquid from the vessel--both at rates directly proportional to the rate of solids melting in the vessel. The apparatus comprises an auxiliary vessel containing slush mixture and means for transferring slush mixture to the main vessel at one rate, means for transferring liquid from the main vessel to the auxiliary vessel at another rate, and means for controlling the transfer rates in a prescribed manner.
Refrigeration apparatus for cooling or freezing products such as protein materials includes a drum through which heat transfer fluid is circulated. A belt is wrapped around part of the drum surface and the product to be refrigerated is applied to the drum surface, being pressed thereagainst by the belt. Either liquid or triple point carbon dioxide is circulated through the drum to cool the product in contact therewith. Other heat transfer fluids such as D-Limonene or DOWTHERM may also be circulated through the drum. A tank and related apparatus for cooling the heat transfer fluid is also disclosed.
Apparatus comprising a freeze exchanger having an aqueous liquid feed stream inlet and an aqueous liquid stream outlet; a closed loop refrigeration system for supplying a refrigerant to the freeze exchanger for indirectly cooling aqueous liquid fed thereto; an ice storage tank; a conduit for withdrawing aqueous liquid, or a mixture of ice and aqueous liquid, from the freeze exchanger outlet and delivering it to the ice storage tank; a conduit for removing cold aqueous liquid from the ice storage tank and feeding it to a heat exchanger to cool fluid used for cooling purposes; and a conduit for removing warm aqueous liquid from the heat exchanger and feeding it to the ice storage tank, or to the freeze exchanger, or partially to both. A method of cooling making use of the apparatus is also disclosed.
A system for storing electrical energy in the form of triple-point CO.sub.2 and then using such stored energy plus heat to generate electrical power. A reservoir of carbon dioxide liquid at about the triple point is created in an insulated vessel. Liquid carbon dioxide is withdrawn and pumped to a high pressure, which high pressure carbon dioxide is heated and expanded to create rotary power which generates electrical power. The discharge stream from the expander is cooled and returned to the vessel where carbon dioxide vapor is condensed by melting solid carbon dioxide. A fuel-fired gas turbine connected to an electrical power generator can be used to heat the high pressure carbon dioxide, and an ambient air stream flowing toward the gas turbine can be cooled by giving up heat to the high pressure carbon dioxide stream. The returning expanded carbon dioxide stream can be returned to a separate auxiliary vessel, and liquid carbon dioxide pumped from such auxiliary vessel to a main vessel wherein solid carbon dioxide is formed and then transferred to the auxiliary vessel.
