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: A process for controlling operation of a heating, ventilation and air conditioning system broadly comprises providing a heating, ventilation and air conditioning system having an evaporator, a condenser, a compressor having an inlet and an outlet, and at least one flow control device; measuring a performance parameter of the heating, ventilation and air conditioning system; determining a performance parameter measurement of the flow indicative of onset of surge; determining a surge line of the heating, ventilation and air conditioning system based upon the performance parameter measurement; and independently controlling the at least one flow control device based upon the performance parameter to mitigate an onset of the surge.

Abstract: The impeller is preferably modified to use back swept, radial or forward swept blades to accommodate relatively low, medium and high lift, respectively applications for both centrifugal compressor and turbine rotor use.

Abstract: A method is provided for controlling operation of a compressor having an inlet and an outlet, a variable geometry diffuser communicated with the outlet, and inlet guide vanes communicated with the inlet, wherein the method includes the steps of: determining a loading parameter indicative of onset of surge; and independently controlling the inlet guide vanes and the variable geometry diffuser based upon the loading parameter so as to allow increase in efficiency and stable operation of the compressor.

Abstract: A machine designed as a centrifugal compressor is applied as an organic rankine cycle turbine by operating the machine in reverse. In order to accommodate the higher pressures when operating as a turbine, a suitable refrigerant is chosen such that the pressures and temperatures are maintained within established limits. Such an adaptation of existing, relatively inexpensive equipment to an application that may be otherwise uneconomical, allows for the convenient and economical use of energy that would be otherwise lost by waste heat to the atmosphere.

Abstract: A power conversion system which uses a plurality of transistors to convert DC power to AC power is made more efficient by the use of liquid refrigerant to cool the transistors. A plurality of passages are formed in a cold plate on which the transistors are mounted, and liquid refrigerant is flashed into the passages to cool the cold plate and the transistors. The liquid refrigerant can by derived from a condenser from an organic rankine cycle or a vapor compression cycle.

Abstract: A method of operating an organic rankine cycle system wherein a liquid refrigerant is circulated to an evaporator where heat is introduced to the refrigerant to convert it to vapor. The vapor is then passed through a turbine, with the resulting cooled vapor then passing through a condenser for condensing the vapor to a liquid. The refrigerant is one of CF3CF2C(O)CF(CF3)2, (CF3)2 CFC(O)CF(CF3)2, CF3(CF2)2C(O)CF(CF3)2, CF3(CF2)3C(O)CF(CG3)2, CF3(CF2)5C(O)CF3, CF3CF2C(O)CF2CF2CF3, CF3C(O)CF(CF3)2.

Abstract: In a comfort system having a combination furnace and air conditioner, the two are operated simultaneously at periods of time in which emergency power is desired, with the air conditioning system being temporarily converted to cause the flow of refrigerant to pass from the evaporator to a high pressure side of said compressor rather than to the low pressure side thereof to thereby drive the compressor in reverse such that it operates as a turbine. The turbine then drives its motor in reverse to generate power to be supplied to the various components of the systems and to other appliances during emergency mode operation.