This study focused on the evaluation of TiO2 nanofluid coolant for automobile engine cooling applications. It was observed that, about 3% of thermal conductivity enhancement and above 10% convective heat transfer enhancement could be achieved with the usage of 1.0 wt.% TiO2 nanofluid coolant compared to base coolant without nanoparticles. More importantly, corrosion-inhibiting properties of TiO2 nanofluid coolant were investigated, which indicated that the nanofluid coolant possess the characteristics of a qualified engine coolant should have. The evaluation results showed that the nanofluid coolant could be a promising engine coolant for automobiles.

The low-temperature viscosity of anhydrous coolant is reduced by adding ethylene glycol to the propylene glycol base fluid, and the evaluation method of low-temperature fluidity is also studied. The experimental results show that the low-temperature fluidity of anhydrous coolant can be greatly improved by the participating of ethylene glycol. Freezing point method is usually used for measuring the low temperature performance of coolant, but for “long icing process” anhydrous coolant, beginning-crystal point shows more practical reference value. Therefore, freezing point, beginning-crystal point and low-temperature fluidity should be considered at the same time when evaluation the low temperature performance of anhydrous coolant.

Ultrasonic vibratory cavitation erosion tests were carried out on studying the cavitation erosion protection performance of different type of heavy-duty engine coolants for cast iron material of wet sleeve cylinder liners. The influence of coolant type, freezing point, corrosion inhibitor content and test duration on anti-cavitation performance were analysed. The experimental results showed that the anti-cavitation erosion performance of organic acid type heavy-duty engine coolants were better than the inorganic salt type heavy-duty engine coolants. For the same formulation coolant, increasing the content of ethylene glycol or corrosion inhibitor can improve the anti-cavitation erosion performance. With the extension of ultrasonic vibration test time, the anti-cavitation erosion protection performance for cast iron was reduced.

An organic acid antifreeze coolant was developed in this paper which consisted mainly of deionized water, organic acid, pyrrole compound, alkali and dye. Glycol, nitrite, chromate, inorganic phosphate and other harmful additives were not contained in this formulation. The coolant overcomes the disadvantages in environmental protection, heat transfer and cost of the current technology which uses the ethylene glycol as antifreeze. The coolant has good low temperature protection, thermal conductivity and corrosion protection performance. Further more, the coolant has the advantages of simple preparation, good storage stability and a promising prospects.

In order to meet the demand of heat rejection requirement of heavy-duty engine, a novel nanofluid heavy-duty coolant was developed in this paper by taking advantage of nanofluid heat transfer technique and organic acid technique. Comparing with conventional heavy-duty coolant, the heat transfer capacity increased more than 10%, which solved the problems of limited thermal conductivity and convective heat transfer performance. The coolant possessed the characteristics of a qualified engine coolant should have and could be a promising engine coolant.