A closed working fluid system for a regenerative Stirling engine is disclosed. The system employs double-acting pistons arranged with each low temperature (compression) space connected to one hot (expansion) space of an adjacent piston. The low temperature spaces are all connected to a reservoir system employing two separate chambers, one at a high pressure and another at a relatively low pressure. Control means select the reservoir for communication with the working system depending on the torque demand of the engine; the control means also permits fluid flow to pass from any one low temperature space to the selected reservoir when the pressure condition in the low temperature space exceeds the associated reservoir pressure. Independent communication is provided between each pair of adjacent low temperature spaces; the communication is controlled by a valve operating in phase with the phase changes of the double-acting pistons so that only one pair of low temperature spaces are in communication at any one time. The latter communication operates to displace the independent pumping mechanisms employed by the prior art. The apparatus herein allows the integrated compression spaces to increase the pressure of the working fluid system in series.
A power control system for a hot gas engine of the type in which the power output is controlled by varying the mean pressure of the working gas charge in the engine has according to the present invention been provided with two working gas reservoirs at substantially different pressure levels. At working gas pressures below the lower of said levels the high pressure gas reservoir is cut out from the control system, and at higher pressures the low pressure gas reservoir is cut out from the system, thereby enabling a single one-stage compressor to handle gas within a wide pressure range at a low compression ratio.
A power control method and apparatus for a Stirling engine including a valved duct connected to the junction of the regenerator and the cooler and running to a bypass chamber connected between the heater and the cylinder. An oscillating zone of demarcation between the hot and cold portions of the working gas is established in the bypass chamber, and the engine pistons and cylinders can run cold.
A heater head for a multi-cylinder solar powered hot gas engine has a number of heater tubes lined on a conical wall exposed to the radiation. The tubes follow involute curves in two parts. The first parts leave very small gaps between them. The second parts arranged at a larger diameter from the center of said wall follow another involute each tube now leaving such gap relative its neighbor that a returned tube part may be arranged between.
New thermodynamic working fluids with primary application to Stirling-cycle, reciprocating, thermal machines are disclosed which possess a greater dynamic heat transfer coefficient than either hydrogen or helium and which are both chemically inert and easily liquefied. A novel power level control subsystem based on the thermophysical properties of these fluids is disclosed for use in conjunction with Stirling-cycle machines; this new approach greatly simplifies procedures for changing the mean system working pressure, and thereby the instantaneous power level in such machines, during their operation.
