CO.sub.2 Snow producer with heat exchanger

A carbon dioxide snow producer including a liquid carbon dioxide supply line having a first end communicated with a source of liquid carbon dioxide under pressure, a second end of said line including a plurality of spaced spray jet outlet means, a heat exchange structure of high heat exchange capacity, said plurality of spray jet outlet means being arranged closely spaced from and to spray spaced jets of liquid carbon dioxide onto heat exchange surfaces of said heat exchange structure, an intermediate portion of said supply line being in good heat exchange relation with said heat exchange structure, whereby the absorption of heat from said heat exchanger by the spraying of jets of liquid carbon dioxide thereon will in turn absorb heat from said intermediate portion of said line and reduce the temperature of the liquid carbon dioxide flowing therethrough to a temperature at least near the triple point temperature of liquid carbon dioxide thereby enabling almost complete transformation of the liquid carbon dioxide being discharged from said spray jet outlet means directly into carbon dioxide snow and with minimal portions of the jet discharged liquid carbon dioxide being transformed into carbon dioxide gas.

The method of substantially maximum efficiency use of liquid phase changeable refrigerant of the type expandable from liquid into a gas and, when at the triple point temperature and pressure, expandable from a liquid state directly to a solid state, said method comprising passing liquid refrigerant through a supply line from an inlet end of the line toward the opposite outlet end thereof, passing an intermediate length portion of said line in good heat transfer relation with heat transfer means, and discharging liquid refrigerant from said outlet end of said line through spray nozzle means operative to direct spray jets of said liquid refrigerant against said heat transfer means for simultaneously cooling the latter and transforming said spray jets of liquid refrigerant substantially completely directly into refrigerant snow with the cooled heat transfer means serving to cool the liquid refrigerant passing through said intermediate length portion of said line to a temperature closely approaching the triple point temperature of said liquid refrigerant, said method further including the passage of said liquid refrigerant through said line at a pressure generally equal to the triple point pressure of said liquid refrigerant.