Ethane can be used as a refrigerant in cryogenic refrigeration systems. It includes the electrotechnical, heating, ventilating, air conditioning, refrigeration and plumbing industries. Embraco is a manufacturer of compressors for refrigeration systems. Before the advent of refrigeration, evaporative cooling was used for millennia. Prior to the introduction of mechanical refrigeration, cooling was accomplished by delivering ice. This is used to make heat exchangers for refrigeration equipment. Sulfur sticks are burnt to detect small leaks in industrial ammonia refrigeration systems. R-427A is for use in air conditioning and refrigeration applications. Little Swan products are mostly laundry and refrigeration appliances. Turboexpanders are used for refrigeration in industrial processes. They provide greater thrust without significant refrigeration and insulation requirements. Systems combining adsorption, refrigeration and condensation are also being developed. Physical preservation entails processes such as refrigeration or drying. Subcooling phenomena is intimately related to efficiency in refrigeration systems. The performance of vapor compression refrigeration cycles is limited by thermodynamics.