Development of a High-Temperature Coolant for Advanced Diesel Engines

摘要

This study sought to develop a high-temperature coolant for future advanced military diesel engines capable of operating at high temperatures (up to 150 C). The desirable coolant for high-temperature application must have a high boiling point, a low freezing point, good thermal properties (specific heat and thermal conductivity) and must be able to protect the various metals of the cooling system and the engine components against corrosion. In order to evaluate the candidate for high-temperature application under laboratory conditions, the simulated service corrosion test, ASTM D-2570 was conducted at 121 C for 1064 h. Also with this corrosion test mock-up, the cavitation-corrosion test was performed using an aluminum water pump at 121 C for 700 h. The antifreezes used in these tests were mixtures of MIL-A-46153 antifreeze and water containing 50, 60, and 80 wt percent ethylene glycol and similar mixtures containing the antifreeze extender additive, MIL-A-53009. Based on simulated service test results, the antifreeze mixtures containing 50, 60, and 80 wt percent ethylene glycol with antifreeze extender additive were found to be acceptable as potential candidates for the future advanced diesel engine operating at 121 C. Among the three candidate coolants, the antifreeze mixture containing 60 wt percent of MIL-A-46153 with antifreeze extender additive proved to be the optimum coolant for high-temperature application (121 C) based on its boiling point, freezing point, and thermal properties and on the results of the simulated service corrosion and cavitation-corrosion tests.