An expander and a fluid circulation system comprising same are disclosed. The expander comprises a housing, an expansion mechanism, an exhaust pipe, an oil sump and a lubricant discharge channel. The expansion mechanism is provided in the housing to expand a high-pressure fluid into a low-pressure fluid. The exhaust pipe discharges the low-pressure fluid out of the expander and comprises an end portion assembled in a first opening of the housing and provided with an exhaust port; the low-pressure fluid enters the exhaust pipe via the exhaust port. The oil sump stores a lubricant in the housing. The lubricant discharge channel discharges the lubricant in the oil sump into the exhaust pipe and/or an external system pipeline and comprises an inlet end having an inlet located at a predetermined oil level of the oil sump and an outlet end having an outlet.

A method of operating a thermal exchange engine having a thermal energy conduction surface and rotating elements in the vessel which form a plurality of closed working chambers which increase or decrease in volume as the rotating elements move. The method involves placing a phase change fluid in each of the working chambers and operating the vessel as on a closed cycle without addition of phase change fluid into the vessel or removal of phase change fluid from the vessel. The method involves applying thermal energy to the thermal energy conduction surface, thereby thermally increasing or decreasing a pressure inside at least one working chamber positioned adjacent to the thermal energy conduction surface, such that the change in pressure inside the at least one working chamber causes the rotating elements to move the at least one working chamber away from the thermal energy conduction surface.

A man-portable backup power generation method including introducing a compressed nitrogen gas stream into an expander turbine, expanding the compressed nitrogen gas stream within the expander turbine, thereby producing a rotational mechanical output, and introducing the rotational mechanical output into a power generator coupled to the expander turbine, thereby producing an electrical output.

An expander and a fluid circulation system comprising same are disclosed. The expander comprises a housing, an expansion mechanism, an exhaust pipe, an oil sump and a lubricant discharge channel. The expansion mechanism is provided in the housing to expand a high-pressure fluid into a low-pressure fluid. The exhaust pipe discharges the low-pressure fluid out of the expander and comprises an end portion assembled in a first opening of the housing and provided with an exhaust port; the low-pressure fluid enters the exhaust pipe via the exhaust port. The oil sump stores a lubricant in the housing. The lubricant discharge channel discharges the lubricant in the oil sump into the exhaust pipe and/or an external system pipeline and comprises an inlet end having an inlet located at a predetermined oil level of the oil sump and an outlet end having an outlet.

A compressor and waste heat recovery system is disclosed in which mechanical work from a prime mover along with work generated from the waste heat recovery system are used to operate the compressor. A gas producing system is heated by waste heat from operation of the compressor to produce a stream of gas used to drive a turbine. The turbine is in work communication with the compressor. In one embodiment the gas producing system is a metal hydride. An overrunning clutch can be used with the turbine. In one form multiple gas producing systems are used, one of which to emit gas while the other is used to receive and capture the emitted gas.

Systems and methods for compressor unloading detection are provided and include a compressor having a compression mechanism. A controller determines a predicted discharge temperature of the compressor, receives an actual discharge temperature of the compressor, and compares the predicted discharge temperature with the actual discharge temperature. The controller also compares a speed of the compressor with a speed threshold and detects unloading of the compression mechanism based on the comparison of the predicted discharge temperature with the actual discharge temperature and based on the comparison of the speed of the compressor with the speed threshold. The controller performs at least one of generating an alert and a remediating action in response to detecting the unloading of the compression mechanism.

A compressor may include first and second scroll members having first and second scroll wraps, respectively. The scroll members define a suction inlet, a discharge outlet, and fluid pockets moving therebetween. The second scroll member may include a port, and a passage. The port may be in fluid communication with at least one of the pockets. The passage may extend through a portion of the second end plate and may be in fluid communication with the port. A valve assembly may be disposed in the passage and may include a valve member displaceable between open and closed positions. A recompression volume may be disposed between the valve member and the at least one of the pockets. The recompression volume may be less than or equal to approximately one percent of a volume of one of the pockets at a suction seal-off position.

Systems and methods for compressor unloading detection are provided and include a compressor having a compression mechanism. A controller determines a predicted discharge temperature of the compressor, receives an actual discharge temperature of the compressor, and compares the predicted discharge temperature with the actual discharge temperature. The controller also compares a speed of the compressor with a speed threshold and detects unloading of the compression mechanism based on the comparison of the predicted discharge temperature with the actual discharge temperature and based on the comparison of the speed of the compressor with the speed threshold. The controller performs at least one of generating an alert and a remediating action in response to detecting the unloading of the compression mechanism.

Systems and methods for scroll unloading detection are provided and include a scroll compressor having a scroll compression mechanism. A controller determines a predicted discharge temperature of the scroll compressor, receives an actual discharge temperature of the scroll compressor, and compares the predicted discharge temperature with the actual discharge temperature. The controller also compares a speed of the scroll compressor with a speed threshold and detects unloading of the scroll compression mechanism based on the comparison of the predicted discharge temperature with the actual discharge temperature and based on the comparison of the speed of the scroll compressor with the speed threshold. The controller performs at least one of generating an alert and a remediating action in response to detecting the unloading of the scroll compression mechanism.

A fluid expander is disclosed as used in conjunction with an air compressor that is driven by a prime mover. The fluid expander is structured to extract useful work from a fluid stream and add that work to the work provided by the prime mover to the compressor. In some embodiments a clutch can be used to decouple the expander from the compressor if insufficient work is developed by the expander. A gear train can also be used to change the rotational speed prior to work being delivered to the compressor.