Talets akustik och perception

This disclosure relates to a compact, reliable and inexpensive expansion valve for use in a refrigeration system. The valve has one passage to be arranged between the evaporator and the compressor of the refrigeration system and has a second passage to be arranged between the condenser and evaporator in the system. A valve member disposed in the second passage is spring biased to normally close that passage and a wire of a selected nickel-titanium alloy or the like is connected to the valve member and disposed in the first valve passage, this wire being adapted to abruptly contract in length for moving the valve member to open the second valve passage when the wire is heated above a selected transition temperature. A small electrical current is directed through the wire so that, when sufficient refrigerant has been released into the evaporator through the second valve passage, droplets of liquid refrigerant in the atmosphere moving from the evaporator to the compressor of the refrigeration system through the first valve passage cool the alloy wire and permit the noted spring bias to move the valve member to close the second valve passage. However, when no liquid droplets of refrigerant are present in the noted atmosphere, the alloy wire is heated to the noted temperature by the electrical current flowing through the wire, the wire then contracting in length for opening the second valve passage to allow more liquid refrigerant to enter the evaporator.