Abstract: An organic rankine cycle system is combined with a fuel system so as to use the waste heat from the fuel cell to both preheat and evaporate the working fluid in the organic rankine cycle system to thereby provide improved efficiencies in the system.

Abstract: A method and system for operating a cascaded organic Rankine cycle (ORC) system (100) utilizes two waste heat sources from a positive-displacement engine (106), resulting in increased efficiency of the engine (106) and the cascaded ORC system (100). A high temperature waste heat source from the positive-displacement engine (106) is used in a first ORC system (102) to vaporize a first working fluid (118). A low temperature waste heat source from the positive-displacement engine (106) is used in a second ORC system (104) to heat a second working fluid (130) to a temperature less than the vaporization temperature. The second working fluid (130) is then vaporized using heat from the first working fluid (118). In an exemplary embodiment, the positive-displacement engine (106) is a reciprocating engine. The high temperature waste heat source may be exhaust gas and the low temperature waste heat source may be jacket cooling water.

Abstract: An improved transmission vent system for centrifugal compressors comprises a motor compartment, a transmission chamber, an impeller for moving refrigerant in a downstream direction, a guide vane located upstream of the impeller, and a vent pipe connected between the transmission chamber and an area upstream of the impeller and downstream of the guide vane. Refrigerant can be vented from transmission chamber to the area upstream of the impeller and downstream of the guide vane in order to eliminate the pressure differential between the transmission chamber and the compressor suction area upstream of the impeller during start-up.

Abstract: A centrifugal compressor having a variable wall diffuser section that is controlled in response to measured system parameters in order to maintain the compressor at optimum efficiency over extended operating range.

Abstract: In a centrifugal gas compressor the capacity and the prewhirl of the entering gas are both controlled by reciprocating a plug which is located in the flow path. The plug coacts with tapering walls of the flow path to vary the minimum cross-sectional area of the flow path. Additionally vanes are provided either in the wall of the flow path or on the plug. The vanes transition from an axial direction to a helical direction and of reducing height in a downstream direction so as to produce increasing prewhirl with decreasing capacity. Alternatively, prewhirl may be provided without capacity control.