Abstract: An evaporator for a refrigeration chiller includes a tube bundle in which at least a portion of the tubes of the tube bundle are immersed in a pool which include both liquid refrigerant and is lubricant. Liquid refrigerant and lubricant are deposited into the pool at a first pool location. Because of the vaporization of refrigerant that occurs within the pool, a pattern of flow is established and managed that causes the lubricant in the pool to migrate from the location of its deposit into the pool to a second pool location. An outlet is provided at the second pool location from which lubricant is drawn out of the evaporator.

Abstract: A falling film evaporator for use in a vapor compression refrigeration chiller preferably employs a two-phase refrigerant distributor that overlies the tube bundle in the evaporator shell. The tube bundle defines at least one vapor lane which facilitates the conduct of refrigerant vapor from the interior of the tube bundle to the exterior thereof in a manner which does not substantially affect the vertically downward flow of liquid refrigerant through the tube bundle and across the vapor lane.

Abstract: Efficient two-phase refrigerant mixture distribution is accomplished in a falling film evaporator by use of a refrigerant distributor disposed internal of the evaporator shell which overlies the evaporator tube bundle and which internally causes said two-phase refrigerant mixture to be made available along essentially the entire length and across essentially the entire width of the tube bundle prior to the delivery of the refrigerant out of the distributor.

Abstract: A refrigerant distributor for use in a shell and tube evaporator has a decreasing cross-sectional area which uniformly distributes refrigerant to the tube bundle within the evaporator shell and operates with a small distributor to evaporator pressure drop.

Abstract: A fluid level sensor. The sensor comprises a housing; a chamber enclosed by the housing; a liquid port in a lower area of the housing operable to connect the chamber to a lower, liquid containing area of a heat exchanger; and a gas port located in an upper area of the housing and operable to connect the chamber to an upper, vapor containing area of a heat exchanger. The sensor includes first and second apertures in the housing; and cooling conduit passing through the chamber and through the first and second apertures and operable to cool the chamber. There is at least one sensor located in the chamber and adapted to sense a temperature of fluid in the chamber.

Abstract: A liquid refrigerant distributor for use within a heat exchanger having a body of heat exchange tubes. The distributor comprises a mesh screen and a liquid refrigerant sprayer. The liquid refrigerant sprayer is adapted to spray refrigerant on the mesh screen. The mesh screen being adapted to pass liquid and vaporous refrigerant but also to direct liquid refrigerant onto the heat exchange tubes.

Abstract: Compression refrigeration apparatus for removing heat from a heat load using a falling film evaporator, operated with an azeotropic refrigerant and utilizing a spray tree distribution system that distributes a refrigerant film on a heat exchange surface by spraying liquid refrigerant onto a surface and allowing the refrigerant to drip onto the primary heat exchange surface. The apparatus allows for efficient recovery of lubricant deposited in the evaporator without redistributing the lubricant within the evaporator. In an alternative embodiment, liquid refrigerant is sprayed onto a mesh screen where it drips onto the primary heat exchange surface.

Abstract: Compression refrigeration apparatus for removing heat from a heat load using a falling film evaporator, operated with an azeotropic refrigerant and utilizing a spray tree distribution system that distributes a refrigerant film on a heat exchange surface by spraying liquid refrigerant onto a surface and allowing the refrigerant to drip onto the primary heat exchange surface. The apparatus allows for efficient recovery of lubricant deposited in the evaporator without redistributing the lubricant within the evaporator. In an alternative embodiment, liquid refrigerant is sprayed onto a mesh screen where it drips onto the primary heat exchange surface.

Abstract: Compression refrigeration apparatus for removing heat from a heat load using a falling film evaporator, operated with an azeotropic refrigerant and utilizing a vapor-liquid separator, preferably inside the evaporator vessel. In one embodiment, two types of heat exchange surfaces are utilized--one for maximizing the axial distribution of refrigerant film on a heat exchange surface, the other for encouraging liquid refrigerant in contact with a heat exchange surface to boil and evaporate. The apparatus allows for efficient recovery of lubricant deposited in the evaporator without redistributing the lubricant within the evaporator.