Abstract: A method of manipulating the rate of homogeneous nucleation of silicon as either a particulate solid or liquid settling out of the gaseous phase during the pyrolysis of silane homologs by controlling the quantity of halogen within the pyrolysis medium. The rate of homogeneous nucleation can be maintained sufficiently low (below 1 silicon nucleus/cm.sup.3 /sec) so as to avoid power formation with a minimum amount of halogen.

Abstract: A solar heat collector is described in which a filamentary heat absorber is disposed within a housing having opaque, heat-insulated sides and bottom and a plurality of partially evacuated tubular members substantially transparent to incident solar radiation mounted on the top thereof. Means are provided for supplying fluid flow to the housing and removing fluid flow from the housing to provide for the transfer of heat energy from the filaments in the absorber to the fluid flow. Light entering the housing through the transparent members enters the filamentary heat absorber, is internally reflected and absorbed. That portion of the light passing through the filamentary heat absorber strikes a reflecting layer, which redirects heat and light back into the filamentary heat absorber.

Abstract: The average size of Glauber's salt crystals formed by crystallization of Na.sub.2 SO.sub.4 from aqueous solution in systems comprising Na.sub.2 SO.sub.4, H.sub.2 O and Glauber's salt is decreased by including a fluorine-containing surfactant in the system.

Abstract: Encapsulation of Na.sub.2 SO.sub.4 particles by Glauber's salt crystals formed by crystallization of Na.sub.2 SO.sub.4 from aqueous solution in systems comprising Na.sub.2 SO.sub.4, H.sub.2 O and Glauber's salt is decreased by including ethylene glycol monobutyl ether in the system.

Abstract: The formation of large crystals during the cooling and crystallization of Glauber's salt is prevented by the addition of ferric ions to the system.

Abstract: A heat exchange device for the introduction of thermal energy into and removal of thermal energy from liquid-solid phase change material is described in which the phase change material is maintained in a container, which is slowly rotated about a generally horizontal axis at a substantially constant rotational speed. Means are provided for automatically nucleating the phase change material as required for cyclic operation. The invention is of particular utility in the use of incongruently melting hydrates for the storage of thermal energy.

Abstract: A method for the storage and retrieval of thermal energy is disclosed, which in a two phase, two component system is able to utilize both the sensible heat of water (always one of the components) and the heat of fusion of the second component (a salt which forms a hydrate). The system to be employed must be graphically definable in a phase diagram including a liquidus, the compositional range of the system being selected so as to lie within the compositional range of the liquidus along which the system is to operate during both the heating and cooling cycles.