Abstract: A cooling system includes a unit for processing product to be cooled or frozen. A secondary refrigeration loop is connected to this unit and introduces a refrigerant at or near atmospheric pressure into the unit. The secondary refrigeration loop may be open or closed. The secondary loop includes a secondary heat exchanger for cooling the refrigerant. A primary, closed refrigeration loop, operating at a pressure of not less than 2 atmospheres, includes a forward flow path which comprises a primary refrigerant compressor for producing compressed primary refrigerant, a primary heat exchanger for receiving and cooling the compressed primary refrigerant and an expander for further cooling and transferring the compressed refrigerant to the secondary heat exchanger to enable cooling of the secondary refrigerant. The primary loop further includes a return flow path from the secondary heat exchanger to the primary refrigerant compressor and to the primary heat exchanger.

Abstract: A porous boiling surface and method of making, which surface comprises a flame-sprayed matrix of ferrous alloy powder on a metal substrate, the matrix being characterized by having irregularly spaced, angled macropores which extend partly through the thickness of the matrix and which improve the boiling perfrmance of the surface.

Abstract: A boiling surface layer is formed on a thermally conductive wall comprising a plurality of ridges separated by grooves provided at microscopic density, with outer sections of the ridges partly deformed into adjacent grooves to provide sub-surface cavities with restricted openings to the outer surface and sub-surface, openings between some of the cavities.