Systems and methods have demonstrated the capability of rapidly cooling the contents of pods containing the ingredients for food and drinks.

An aspect of the present invention provides a refrigerating machine oil containing a mixed base oil of a first hydrocarbon base oil having a kinematic viscosity at 40° C. of less than 6 mm.sup.2/s and a second hydrocarbon base oil having a kinematic viscosity at 40° C. of 6 mm.sup.2/s or more, wherein a (A)/(B) ratio is more than 1 and 1.5 or less, wherein (A) is a kinematic viscosity at 40° C. of the mixed base oil, and (B) is the kinematic viscosity at 40° C. of the first hydrocarbon base oil.

Methods and systems for liquefying natural gas using environmentally-friendly low combustibility refrigerants are provided. Methods of liquefaction include cooling a fluid in an LNG facility via indirect heat exchange with an environmentally-friendly low combustibility refrigerants that are propane, ethane and methane mixed with small amounts of fluorinated olefin, but still within close proximity to the boiling points of the pure refrigerants such that the mixed refrigerants can still be used in an optimized cascade process.

The invention relates to the use, as a liquid phase heat-transfer medium, of a fluid having a boiling point in the range of from 200° C. to 400° C. and a boiling range below 80° C., said fluid comprising more than 95% by weight isoparaffins and less than 3% by weight of naphthens, a biocarbon content of at least 95% by weight, containing less than 100 ppm by weight aromatics.

An aspect of the present invention provides a refrigerating machine oil containing: a lubricating base oil; and a polymer containing an unsaturated carboxylic acid ester as a monomer unit, wherein the unsaturated carboxylic acid ester contains an ester of an unsaturated carboxylic acid and an alcohol having a hydrocarbon group represented by the following formula (1):

##STR00001##

wherein x represents an integer of 5 to 18, and y represents an integer of 3 to 18.

Systems and methods have demonstrated the capability of rapidly cooling the contents of pods containing the ingredients for food and drinks.

The refrigeration oil composition for HFC-based refrigerants or HC-based refrigerants of the invention includes a product of the esterification of an alcohol ingredient including pentaerythritol and dipentaerythritol and a fatty acid ingredient including at least one of a linear or branched fatty acid having 5 carbon atoms and a linear or branched fatty acid having 6 carbon atoms and at least one of a linear or branched fatty acid having 8 carbon atoms and a linear or branched fatty acid having 9 carbon atoms, wherein at least one of the fatty acid having 5 carbon atoms and the fatty acid having 6 carbon atoms in the fatty acid ingredient accounts for 20 to 100% by mol of the total amount of the fatty acid ingredient, and either the alcohol ingredient or the fatty acid ingredient is a mixture.

A method for liquefying a natural gas primarily including methane, preferably at least 85% of methane, the other components essentially including nitrogen and C2-C4 alkanes, in which the natural gas to be liquefied is liquefied by circulating at a pressure P0 no lower than the atmospheric pressure (Patm), P0 preferably being higher than the atmospheric pressure, in at least one cryogenic heat-exchanger (EC1, EC2, EC3) by a counter-current closed-circuit circulation in indirect contact with at least one stream of coolant gas remaining in the compressed gaseous state at a pressure P1 that is entering the cryogenic heat-exchanger at a temperature T3′ that is lower than T3, T3 being the liquefaction temperature of the liquefied natural gas at the pressure P0 at the output of said cryogenic exchanger, characterized in that the coolant gas includes a mixture of nitrogen and at least one other component selected from among neon and hydrogen.

The present invention provides a working fluid composition for a refrigerating machine, comprising: a refrigerating machine oil comprising, as a base oil, a mixed ester of (A) a complex ester obtainable by synthesis of at least one polyhydric alcohol selected from neopentyl glycol, trimethylolpropane and pentaerythritol, a C6-C12 polybasic acid, and a C4-C18 monohydric alcohol or a C4-C18 monocarboxylic fatty acid, and (B) a polyol ester obtainable by synthesis of at least one polyhydric alcohol selected from neopentyl glycol, trimethylolpropane, pentaerythritol and dipentaerythritol, and a C4-C18 monocarboxylic fatty acid, in a mass ratio of (A) the complex ester/(B) the polyol ester of 5/95 to 95/5; and a hydrocarbon refrigerant having 3 or 4 carbon atoms, wherein a refrigerant dissolved viscosity, at a temperature of 80° C. and an absolute pressure of 1.5 MPa, is 1.0 mm.sup.2/s or more.

In an aspect, the present invention provides a refrigerating machine oil comprising a poly(meth)acrylate as a base oil, wherein the poly(meth)acrylate comprises a hydrogenated poly(meth)acrylate, a content of a unit having a carbon-carbon double bond present at a terminal in the poly(meth)acrylate is 6% by mole or less relative to total units constituting the poly(meth)acrylate, and a kinematic viscosity at 40° C. of the hydrogenated poly(meth)acrylate is 1 to 1000 mm2/s, the refrigerating machine oil being used with a refrigerant comprising a refrigerant selected from difluoromethane, a mixture of difluoromethane and pentafluoroethane, a mixture of difluoromethane, pentafluoroethane, and 1, 1, 1, 2-tetrafluoroethane, a mixture of pentafluoroethane, 1, 1, 1, 2-tetrafluoroethane, and 1, 1, 1-trifluoroethane, an unsaturated hydrofluorocarbon, a hydrocarbon, and carbon dioxide.