Engineering topics
Publications and source records attributed to Miller, C. G..
Array uses low-cost materials and heavy construction methods to make collection and storage of solar energy economical on large scale required for commercial operation. Series of long trenches are dug side by side over an area large in comparison to heat diffusivity of soil.
A solar heat collection system is provided by utilizing a line-focusing device that is effectively a cylindrically curved concentrator within a protected environment formed by a transparent inflatable casing. A target, such as a fluid or gas carrying conduit is positioned within or near the casing containing the concentrator, at the line focus of the concentrator. The casing can be inflated at the site of use by a low pressure air supply to form a unitary light weight structure. The collector, including casing, concentrator and target, is readily transportable and can be used either at ground level or on rooftops. The inflatable concentrator can be replaced with a rigid metal or other concentrator while maintaining the novel advantages of the whole solar heat collection system.
A three dimensional tracking solar energy concentrator, consisting of a stretched aluminized polymeric membrane supported by a hoop, was presented. The system is sturdy enough to withstand expected windage forces and precipitation. It can provide the high temperature output needed by central station power plants for power production in the multi-megawatt range.
A photoionization technique was used to study flow characteristics in an expansion tunnel. Vertical surveys of the axial component of flow velocity just downstream from the nozzle exit were obtained, and estimates of freestream density were inferred from the velocity measurement technique. The pitot pressure was measured and compared to the average axial component of velocity as a function of time for the two cases when air and CO2 were used as test gases. Vertical velocity and static density profiles at the nozzle exit are presented for the case when CO2 was used as test gas. Experimental results were used to determine the diameter and uniformity of the test core at the nozzle exit and the duration of the quasi-steady flow period. These data are relevant to evaluation of the suitability of operating an expansion tube as an expansion tunnel. The expansion tunnel is an expansion tube with a conical nozzle positioned at the exit of the acceleration section, so that nozzle entrance flow conditions are hypersonic and characterized by hypervelocity.
A method for converting heat energy from low temperature heat sources to higher temperature was developed. It consists of a decomposition chamber in which ammonia is decomposed into hydrogen and nitrogen by absorbing heat of decomposition from a low temperature energy source. A recombination reaction then takes place which increases the temperature of a fluid significantly. The system is of use for the efficient operation of compact or low capital investment turbine driven electrical generators, or in other applications, to enable chemical reactions that have a critical lower temperature to be used. The system also recovers heat energy from low temperature heat sources, such as solar collectors or geothermal sources, and converts it to high temperatures.
A study was conducted to examine the effect of synchronization of an electromagnetically opened tertiary diaphragm with flow arrival at the diaphragm on the pitot pressure measured at the test section of an expansion tunnel. The effect of tertiary diaphragm pressure ratio (ratio of initial nozzle pressure to quiescent acceleration section pressure) on the pitot pressure time history is also determined. The inadequacy of a pressure transducer protection arrangement used in previous expansion tube and expansion tunnel tests was revealed.
Method predicts absorption of hydrogen into metals. Process can aid designers of hydrogen-storage facilities for electric power plants.
A resume' of operating experiences with the Langley Expansion Tube is presented. The driver gas was unheated helium at a nominal pressure of 5000 psi and the majority of the data presented are for air and carbon dioxide test gases. The primary purpose of these data is to illustrate the effects of various parameters on quasi-steady test flow duration, as well as free stream and post-normal shock flow conditions. The discussion shows that the Langley Expansion Tube is an operational facility capable of producing good quality, highly repeatable, quasi-steady flow for test times sufficient to establish flow about blunt axisymmetric and two-dimensional models.
Scheme based on chemical decomposition and recombination converts energy collected at relatively low temperatures (300 C) to higher temperatures required for efficient operation of steam-driven electrical generators. Approach uses one or more cyclical reversible chemical reactions in which compound is made to decompose and absorb thermal energy at low temperature by shifting equilibrium.
Electrode in cylinder permits charge to transfer during top dead center compression stroke in modified Otto-cycle engine. Charge transfer produces spark which causes ignition of droplets without resorting to other ignition devices which are incapable of igniting ultralean mixtures.
A cryostat system for cooling a device to a temperature on the order of 2 K or less includes a dewar, in which helium, in other than the superfluid state, is stored. Helium flows from the dewar through a heat exchanger tube and a restrictor tube, which controls the helium flow rate, into the cavity of a heat exchanger, to whose outer wall the device to be cooled is attached. A pressure regulator value controls the pressure in the cavity to be very low. As the helium exits the restrictor tube into the cavity, due to low pressure cavity, it becomes an aerosol mixture of helium gas and superfluid helium droplets at the desired temperature. The latter form a thin layer or film of superfluid helium on the inner side of the heat exchanger wall and thereby cool the device, which is attached to the wall to the desired temperature.
A continuous HCl in-air indicator was developed which consists of a tube-like element with an inlet end through which a continuous stream of air containing HCl enters. The air flows downstream from the inlet end and exits the element's outlet end. Positioned between the element's inlet and outlet ends are first and second spaced apart photoelectric units, which are preferably positioned adjacent the inlet and outlet ends, respectively. Ammonia gas is injected into the air, flowing through the element, at a position between the two photoelectric units. The ammonia gas reacts with the HCl in the air to form ammonium chloride particles. The difference between the outputs of the two photoelectric units is an indication of the amount of HCl in the air stream.
Positive and/or negative pressure is used to trap airborne particles against a filter. Positive pressure is provided by low molecular weight gas (He or H) to achieve high particle velocity and high capture percentage. Trapped particles are examined under electron microscope.
Steady stream of air is drawn into system and passes between light source and photocell. Incoming gases are sprayed with ammonia forming white cloud of NH4Cl if any HCl is present.
An atmosphere sample is described which includes a very thin filter element with straight-through holes on the order of 1 micron. A sample of air with particles to be examined is driven by means of a pressurized low molecular weight gas, e.g., He to the filter element front side. A partial vacuum may be present at the back side of the filter element. The pressure differential across the filter element is just below the rupture point of the filter element. Particles smaller than filter holes are deposited on the filter element. When using a filter element of plastic material of a thickness on the order of 10 microns, a stainless steel back-up plate and a diffusion member are used to support the filter element when subjected to a pressure differential on the order of a few hundred atmospheres.
Hildebrand-Scott (1950) solubility parameters can be obtained for metals and alloys by calculating the cohesive energy density (CED), equal to the square of the solubility parameter, and a function of the heat of sublimation and the atomic volume. It is suggested that the solubility parameter permits estimation of the hydrogen storage capacity of an alloy and that alloys with a solubility parameter approximately equal to the parameter for hydrogen will have greater hydrogen storage capacity than other alloys. Equilibrium pressure - temperature relationships for some metal hydrides are presented in conjunction with the calculated solubility parameter and correlated with characteristics which would be useful in hydrogen-powered vehicles. Alloy properties which increase the amount of nonstoichiometric reversible hydrogen absorption are discussed.
Flow establishment results are presented as obtained from shock standoff distance, pressure, and heat transfer measurements in the Langley expansion tube. The models tested were flat-faced cylinders with varying radius and a sphere with a constant radius, and they were positioned at the acceleration section exit and tested in the open jet at zero angle of attack. The experimental results were obtained as spinoff from various studies using helium, air, and CO2 test gases at freestream velocities in the range 5-7 km/sec. Time histories of shock detachment distance illustrate that the shock formation about the smaller-radii flat-faced cylinders and the sphere is symmetrical, whereas a complex, asymmetric formation is observed for the larger-radii cylinders. Flow is shown to establish more readily about the sphere than a flat-faced cylinder of the same diameter. A quasi-steady flow exists about relatively large blunt models during two-thirds of the approximate 250-microsec expansion tube test period.
Smaller heat-collector is moved to stay in focus with the sun, instead of moving reflector. Tracking can be controlled by storing data of predicted solar positions or by applying conventional sun-sensing devices to follow solar movement.