NOVELTY - Composition-I comprises 1,1-difluoroethene, a second component comprising hexafluoroethane and/or ethane, and optionally carbon dioxide.    USE - The composition-I is useful: in a heat transfer device preferably refrigeration device such as ultra-low temperature refrigeration system, mechanical power generation and a sprayable composition; cleaning, cooling and heating an article; extracting a substance from biomass; extracting a material from an aqueous solution or from a particulate solid matrix; retrofitting the heat transfer device; generating greenhouse gas emission credit; and reducing the environmental impact arising from the operation of a product from fields of air conditioning, refrigeration, heat transfer, aerosols or sprayable propellants, gaseous dielectrics, flame suppression, solvents, cleaners, topical anesthetics, and expansion applications (all claimed). The heat transfer device is useful in automotive field.    ADVANTAGE - The composition-I is less flammable than 1,1-difluoroethene alone or non-flammable at ambient temperature, preferably 60 degrees C, and provides improved properties such as low greenhouse (or global) warming potential (GWP), performance, flammability characteristics and toxicology to the refrigerant used in refrigeration devices with less or without modification.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a sprayable composition comprising material to be sprayed and a propellant comprising the composition-I;    (2) a method for cooling an article, comprising condensing the composition-I and evaporating the composition-I in the vicinity of the article to be cooled;    (3) a method for heating an article comprising condensing the composition-I in the vicinity of the article to be heated and evaporating the composition;    (4) a method for extracting a substance from biomass comprising contacting biomass with a solvent comprising the composition-I, and separating the substance from the solvent;    (5) a method for cleaning an article comprising contacting the article with a solvent comprising the composition-I;    (6) a method for extracting a material from an aqueous solution or from a particulate solid matrix comprising contacting the aqueous solution or the particulate solid matrix with a solvent comprising the composition-I, and separating the material from the solvent;    (7) a heat transfer device and a mechanical power generation device containing the composition-I;    (8) a method for retrofitting the heat transfer device comprising removing an existing heat transfer composition, and introducing the composition-I;    (9) a method for reducing the environmental impact arising from the operation of a product comprising an existing compound or composition, comprising replacing at least partially the existing compound or composition with the composition-I;    (10) a method for generating greenhouse gas emission credit comprising (i) replacing an existing compound or composition with the composition-I having a lower global-warming potential than the existing compound or composition, and (ii) obtaining greenhouse gas emission credit for the replacing step;    (11) a compostion comprising a stabilizer and composition-I; and    (12) a compostion comprising a flame retardant and composition-I.