Metallic screen-integrated SC-LADs have proven flight heritage over the last five decades in the space industry. A SC-LAD is generally designed using metallic screens as porous material. Thus, an optimum balance of properties of porous screens is required to ensure a satisfactory performance for the desired application. On the other hand, small pores lead to an increase in the flow-through-screen pressure drop which is not desirable and limits the permissible outflow rate of the liquid. In general, a porous screen with a high bubble point is desirable which means that a smaller bubble point diameter is required. The selection of optimal porous screens for a particular application/mission depends on the environmental conditions along with the required outflow. It depends on the properties of the liquid and the screen, as well as on the superficial velocity in the same direction of the liquid flow. It takes into account the pressure loss that occurs as the liquid moves across the wetted area of the porous screen. Besides the bubble point pressure, another important parameter affecting SC-LAD performance is the flow-through-screen pressure drop. It depends on parameters such as the surface tension of the liquid, the contact angle between the liquid and the solid, and the biggest pore window size, known as the bubble point diameter of the porous screen. It is the maximum pressure difference between the liquid and gas phases that the porous screen can withstand. The bubble point of the porous screen is the most important performance evaluator for a SC-LAD. Liquid can enter into the channel through the porous screen but the entry of the gaseous phase will be blocked as long as the total pressure drop across the porous screen is less than the bubble point pressure. A typical SC-LAD is defined as a closed channel with three solid walls and one porous wall. A screen channel liquid acquisition device (SC-LAD) is a type of liquid acquisition device that works according to the principles mentioned above. Based on capillary action, a saturated porous medium can act as a barrier for gas ingestion under a specific set of conditions, and ensure a gas-free supply of propellant. Porous media play an important role in phase-separation applications. In the absence of gravity, capillary forces become the dominant forces controlling the liquid–gas interface inside the tank. One example is a gas-free liquid propellant supply from the propellant tank to the engine or the refueling of spacecraft from a supply tank in microgravity. Phase separation is a critical task for fluid management in many space applications. The removed liquid from the SC-LADs was particle-free, thus representing a potential for applications in a harsh chemical environment or broad-range temperatures. SC-LADs with the same open porosity but smaller pore window sizes showed a higher pressure drop across the screen and bubble ingestion at higher values of effective screen area when increasing the applied removal volumetric flow rate. On the other hand, SC-LADs with an open porosity of 65% were limited to 2 mL s −1 as the pressure drop across these screens was relatively higher. On the one hand, SC-LADs with an open porosity of 79% removed gas-free liquid up to a volumetric flow rate of 4 mL s −1. The pore window size distributions and bubble point tests indicate crack-free screens. The pore window sizes and open porosity varied from 6 µm to 43 µm and 65% or 79%, depending on the freezing temperature or the solid loading, respectively. Therefore, SiOC screens with aligned pores were fabricated via freeze-casting and applied as a SC-LAD. The development of porous ceramic screens with high chemical stability, low density, and thermal conductivity can lead to promising screen channel liquid acquisition devices (SC-LADs) for propellant management under microgravity conditions in the future.
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