Abstract: The height of a layer of material formed by molten metal disposition is measured by ejecting the material as elongate extrusions and measuring the time required for each extrusion to contact the workpiece, then using this time interval along with the speed at which the extrusion is ejected to measure the gap between the ejection head and the workpiece. This gap is then used for calculating the height of the previous layer. By making the workpiece and the ejected material electrically conductive, this time interval can be measured by noting when electric current flows through the extrusion.

Abstract: A method and an apparatus (10) eject on demand a discrete droplet (12) of liquid at a high temperature along a predetermined trajectory (18) by transferring a physical impulse from a low temperature environment to a high temperature environment. The ejector apparatus includes a vessel (26) having an interior (24) that contains a high-temperature liquid (14), such as liquid metal, Al, Zn or Sn. The interior includes an inlet end (30) that receives a thermally insulative impulse transmitting device (22) and a feed supply (34) of the droplet material, and a discharge region (56) having an orifice (16) through which the discrete droplets are ejected. An inert gas is feed through the inlet end and into the vessel to create an overpressure over the liquid so that as the overpressure is increased the droplet size is increased. A heater (70) heats the material contained within the interior.

Abstract: A free-form, three-dimensional, solid-phase object (30) is produced from droplets (24) of liquid-phase material having appreciable surface tension and well-defined solidification properties. The liquid-phase material is ejected from an ejection head (20) in discrete droplets onto a substrate (98). The temperature, frequency, size, and trajectory of the droplets and the relative speed of motion between the substrate and the ejection head are adjusted to compensate for the physical properties of the liquid-phase material and the heat dissipation characteristics of the growing object to form a desired object (212).

Abstract: A membrane distillation module is provided with a thin, flexible microporous membrane positioned against an impermeable condensor sheet that is stiffer in bending than the membrane. Distillate vapor diffuses through the membrane from the hot feed flowing rapidly past the membrane, and condenses and collects between, and in intimate contact with, the membrane and the condensor sheet. The condensed distillate is stripped by forces exerted by the hot feed acting on the distillate across the membrane, and flows toward a distillate outlet located in the downstream direction of the hot feed flow. Cold feed flows past the condensor sheet in the counter direction to that of the hot feed for absorbing the latent heat of condensation, and is subsequently additionally heated and introduced into the hot feed channel. Expanded microporous polytetrafluoroethylene (PTFE) is the preferred membrane material, and a spiral-wound assembly is the preferred configuration.