A linear compressor employing a piezoelectric actuator operating in resonance at a frequency substantially below its natural resonant frequency, which is usually of the order of 10 kHz. Low frequency resonance operation of the actuator, of the order of 100 Hz., is achieved by incorporating the actuator and its housing with the moving compression piston, such that the moving mass is substantially increased, and by reduction of the effective piezoelectric stiffness using hydraulic amplification of the actuator displacement. Both these procedures result in a reduction of the actuator resonant frequency. The hydraulic amplification is achieved by using a hydraulic chamber with different sized pistons, linking the actuator motion with motion of the actuator housing, to which the compressor piston is attached. The high efficiency achieved and the lack of moving parts or the need for lubricating oil makes the compressor ideal for use in high reliability and high purity applications.

A vacuum generation system, in particular for applications to hybrid-drive motor vehicles, comprises a vacuum pump (10) arranged to be independently driven by either an internal combustion engine (1 1) or an electric motor (12) depending on the vacuum conditions in utilizing devices (15) and the operating conditions of the internal combustion engine. A pump for use in such a system and a method of vacuum generation by using the system are also provided.

A pumping device includes a working chamber and a piston provided to slide in the working chamber so as to vary the useful volume of the chamber during pumping, and anti-rotation elements for the piston. Advantageously, the anti-rotation elements include an index (107) mounted radially with respect to the axis of the piston and the device includes a longitudinal slot (108), the index being provided so as to move in the slot. Advantageously, the index (107) has two approximately parallel planar faces that extend longitudinally.

An exhaust energy recovery system (EERS) and associated methods for an engine are disclosed. An embodiment of an EERS, for example, includes an inlet duct that is configured to divert exhaust gas from an exhaust duct of the engine into the recovery system and an outlet duct configured to return the exhaust gas to the exhaust duct downstream of the inlet duct. The recovery system is configured to heat components or fluids associated with engine to operating temperatures. The recovery system may be part of a mobile power system that is mounted to a single trailer and includes an engine and a power unit such as a high pressure pump or generator mounted to the trailer. Methods of operating and purging recovery systems are also disclosed.

An exhaust energy recovery system (EERS) and associated methods for an engine are disclosed. An embodiment of an EERS, for example, includes an inlet duct that is configured to divert exhaust gas from an exhaust duct of the engine into the recovery system and an outlet duct configured to return the exhaust gas to the exhaust duct downstream of the inlet duct. The recovery system is configured to heat components or fluids associated with engine to operating temperatures. The recovery system may be part of a mobile power system that is mounted to a single trailer and includes an engine and a power unit such as a high pressure pump or generator mounted to the trailer. Methods of operating and purging recovery systems are also disclosed.

A thermal transpiration device and method of making the same. The device includes a pair of membranes having predetermined thicknesses in order to provide the device with strength and rigidity. The thickness of a portion of each membrane is reduced in the area where thermal transpiration occurs in order to optimize the effectiveness of the thermal transpiration device without scarifying structural integrity of the device.

An electrochemical hydrogen compressor and a support member for an electrochemical cell include, in a flow field member, flow field grooves through which an anode gas (for example, a hydrogen gas) is allowed to flow in a predetermined direction, and a plurality of through holes one ends of which open in the flow field grooves, and other ends of which are in communication with ventilation holes of an anode current conductor. At least a portion of the through holes (for example, discharge through holes) are inclined at an acute angle with respect to an upstream side of the flow field grooves (for example, discharge flow field grooves).

An electrochemical hydrogen compressor and a support member for an electrochemical cell include, in a flow field member, flow field grooves through which an anode gas (for example, a hydrogen gas) is allowed to flow in a predetermined direction, and a plurality of through holes one ends of which open in the flow field grooves, and other ends of which are in communication with ventilation holes of an anode current conductor. At least a portion of the through holes (for example, discharge through holes) are inclined at an acute angle with respect to an upstream side of the flow field grooves (for example, discharge flow field grooves).

A pump system and method of operating the same may utilize two relatively smaller turbines that are attached to and used to power a single pump. The two turbines are releasably coupled to the pump via respective one-way clutches, thereby enabling the use of one or both turbines at a time to power the pump. At low loads (e.g., low pump outputs), only one turbine operates to power the pump, and at higher loads (e.g., high pump outputs), both turbines operate to power the pump. By using two smaller turbines instead of one large turbine, the range-ability of the turbine power at the most efficient operating ranges is increased. This improves the fuel efficiency of the pump system. In addition, the dual turbine driven pump system provides increased reliability by preventing the loss of all power to the pump in the event of a turbine malfunction.

A pump system and method of operating the same may utilize two relatively smaller turbines that are attached to and used to power a single pump. The two turbines are releasably coupled to the pump via respective one-way clutches, thereby enabling the use of one or both turbines at a time to power the pump. At low loads (e.g., low pump outputs), only one turbine operates to power the pump, and at higher loads (e.g., high pump outputs), both turbines operate to power the pump. By using two smaller turbines instead of one large turbine, the range-ability of the turbine power at the most efficient operating ranges is increased. This improves the fuel efficiency of the pump system. In addition, the dual turbine driven pump system provides increased reliability by preventing the loss of all power to the pump in the event of a turbine malfunction.