Air Content Measurement Technique

Abstract

This report is a part of a Master Thesis Project in Electrical Engineering at the faculty of Fluid Mechanics at Chalmers University. The project was performed in collaboration with Volvo Group Truck Technology, one of the major leaders of truck development in the world. The goal of this project was to design and develop a prototype that was able to detect air bubbles in the cooling system. The project started with a literature study, where several measuring techniques were investigated. The focus was on two types of measuring techniques, permittivity or resistivity. The two methods were based on measuring the capacitance or the resistance between a pair of electrodes in the coolant when air bubbles were added. Several prototypes, including various electric circuits, were developed. Between the two designs presented during the development, the capacitive method was further developed. The result of the thesis was a cylindrical capacitive sensor tested in Volvos test rig in order to investigate how well venting of coolant in the cooling system works. As a first product in this area, the prototype was able to detect air bubbles in the test rig. Therefore, improvements are needed in order to use this product in a vehicle.