External Scroll Pump Solution for Continuous Liquid Argon Circulation

Today's cryogenic pumping consist of two vastly different options. The most common, are centrifugal turbopumps with an impeller-inducer combination which rely on high impeller speeds to create pressure. While the high speed makes them more compact, it also limits life. In addition, the impeller design leads to high flow dependence on differential pressure. Also, impellors can have issues handling two-phase flow. Another option is positive displacement technology. These pumps can handle larger differentials then turbopumps, have little flow dependence on pressure, and don't have issues with two-phase flow. The down side is they typically can't achieve speeds over 3000 RPM which makes them larger. Solution to Problem: Air Squared Inc. will develop an external cryogenic scroll pump for continuously filtering cryogenic fluid for high-energy physics experiments, as described in topic 29h for large cryogenic detector technology. The pump will be able to operate with 50% higher volume turnover rate above the nominal case for 25% of the turnover period of 5-10 days. Air Squared Inc. specializes in custom scroll pump solutions, and can easily scale the unit for implementation into larger cryostat applications which involve higher flow rates, pressure differentials, and power requirements. The scroll pump solution will implement optimized geometry and operating conditions specifically for LAr working fluid to maximize performance of the pump. Problem Solving Approach: During Phase I, Air Squared Inc. will (1) develop analytical modeling techniques to accurately predict performance of the pump at various operating conditions, (2) generate a complete solid model of the prototype believed to optimize performance and lifetime of the unit with final drawings, and (3) build a proof-of-concept prototype for performance validation at cryogenic temperatures using liquid Nitrogen. The design will be evaluated using estimated performance, heat dissipation, size and weight, prototype cost, reliability, and technological risk as weighting metrics. Commercial Applications: A strong demand exists for small cryogenic pumps for use in liquid hydrogen fueled aircraft. There has been hydrogen fueled, unmanned aircraft flown as reconnaissance platforms. Typically, these aircraft fuel systems require the hydrogen to be delivered at a pressure of 90 PSIG. Currently this performed by making the operating pressure of the tanks at a minimum of 90 PSIG. This results in tanks that can operate with a safety margin above this pressure. If the tanks could operate at a lower pressure, such as 30 PSIG, the tank walls could be thinner and lighter. The estimated weight savings of a pump system for a hydrogen fueled aircraft is over 400 pounds per aircraft. The scroll pump an important contributor in increasing aircraft endurance or payload.
Key Words: Positive Displacement Pump; Cryogenic Pump; Scroll Pump Technology; Pump; Scroll; Reliability; Maintainability