MIE.36 – Continuous-Flow Apparatus of Shear Sensitive Fluids

• Mario Aguilera
• Wing Ching Gordon Au
• Sagarkumar Patel
• Jonathan Uriostegui

Spraying Systems Co. develops spray technologies for customers using a wide range of fluids in industrial applications. The performance of some of the technologies are measured with time-based spraying trials that require an indefinite period of testing. The susceptibility of degradation from high shear rates of certain fluids prevents the use of a pump to pressurize the liquids. With current technology available trials need to pause when the initial liquid in the pressurized tank is depleted, or the alternative is to have an excess amount of liquid prepared in a larger tank. Spraying Systems Co. aims to provide its customers a portable solution for spraying fluids at a constant pressure with indefinite-flow, without applying high shear rates to the fluids. Indefinite flow allows the customer to adjust the quantity of fluid being sprayed to maximize run times and reduce leftover material. Constant pressure is essential to remove variability in the performance of spraying components. The company has developed a prototype with a two-tank design that alternates filling and pressuring operations to maintain a continuous flow. The goal of the project is to improve the performance of the prototype to deliver constant and indefinite flow that is portable by a single operator, is pressurized by an external air-compressor source, and delivers a run time of 12 hours with a battery source for electrical components implemented into the system. The prototype uses mechanical ball valves to manage filling and spraying operations of feeder-tube tanks. After repeated cycles, the prototype leaks fluid through the exhaust when venting. Design solutions focused on implementing tanks without feeder-tubes and monitoring fill rates for efficiency. Maximum fill rate efficiency is achieved when the tanks are filling at atmospheric pressure. A shuttle valve device was implemented to solve the vulnerability of leaking fluid through the exhaust when filling at atmospheric pressure.The system did not leak with the shuttle valve design, however, separate issues surfaced that prevented continuous flow. Other devices were tested to fill the tanks while open to the atmosphere without achieving the desired results. The fill rate and compression ratio of tanks closed to the atmosphere was analyzed to determine the requirements of the system to achieve continuous flow. The data showed that bigger tanks and reduced cycle periods are necessary to maintain continuous flow. In correlation with fill rate analysis, the maximum continuous flow rate achieved experimentally was 2.3 liters/minute falling short of the goal. With considerations that the packaging design and battery type successfully met the requirements, Spray Systems Co. is satisfied with moving forward with the reduced flow rate. Future improvements of the system are obtainable with additional tanks to increase flow rate while reducing portability or investing resources to implement methods that monitor fluid volume.