Abstract: A method for operation of a closed-cycle power conversion device includes receiving measured thermal information from one or more sensors that sense thermal characteristics of a hot portion of an absorber heat exchanger of a closed-cycle power conversion device which uses a working medium in its operation. The closed-cycle power conversion device is in thermal connection with a heat source, and absorption of heat from the heat source is proportional to a mass or mass flow rate of the working medium. If the measured thermal information is not in a defined normal range, a message is provided of an abnormality in operation of the closed-cycle power conversion device.

Abstract: Pulse tube refrigeration or cooling systems are described which utilize a secondary regenerator or a secondary pulse tube. Use of such a secondary regenerator or pulse tube enables a commercially available pressure oscillator to be incorporated in the cooling system. The commercially available oscillator can be operated at room temperature or approximately so.

Abstract: Pulse tube refrigeration or cooling systems are described which utilize a secondary regenerator or a secondary pulse tube. Use of such a secondary regenerator or pulse tube enables a commercially available pressure oscillator to be incorporated in the cooling system. The commercially available oscillator can be operated at room temperature or approximately so.

Abstract: A Stirling engine solar concentrator system including a primary reflector (10) mounted on a base supporting structure (1), a secondary reflector (14) located at a focus of the primary reflector (10). a receiver (18) located at a focus of the secondary reflector (14), wherein sunrays are reflected from the primary reflector (10) to the secondary reflector (14) and are reflected back from the secondary reflector (14) to the receiver (18), and a Stirling engine (5) located near the receiver (18), characterised by a cooling system of the Stirling engine (5) including a plurality of heat transfer elements (6, 8) mounted on a shaded side of the primary reflector (10), wherein a cooling fluid (19) is arranged to flow between the Stirling engine (5) and the heat transfer elements (6, 8).

Abstract: Pulse tube refrigeration or cooling systems are described which utilize a secondary regenerator or a secondary pulse tube. Use of such a secondary regenerator or pulse tube enables a commercially available pressure oscillator to be incorporated in the cooling system. The commercially available oscillator can be operated at room temperature or approximately so.

Abstract: In recent years piezoelectric actuation has been identified as a promising means of driving miniature Stirling devices. It supports miniaturization, has a high power to volume ratio, can operate at almost any frequency, good electrical to mechanical efficiencies, and potentially has a very long operating life. This invention uses a valve-less hydraulic amplification, creating an oscillating pressure wave sufficiently large to drive a high frequency miniature pulse tube cryocooler. The actuator may be separated from the main body of the cryocooler. The system lack of rubbing parts in the power conversion processes.