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Technical Paper

Instrument for Field Monitoring of Carboxylate Coolants and Heat-Exchange Fluids

For several years now, organic acid based coolants and heat exchange fluids have been introduced on the automotive and industrial market place. The organic acid based coolants provide improved high temperature aluminum corrosion protection and longer drain intervals when compared to traditional coolants. In order to evaluate the organic acid based coolant quality in the field; the end user needs to be able to check several physico-chemical parameters of the coolant. First of all the amount of carboxylate based inhibitors should be determined because the customers can top the system with water. As a result the carboxylates can drop under the minimum required inhibitor level.
Technical Paper

Fleet Evaluation of Propylene Glycol (PG) and Recycled PG Coolant with Extended Life Inhibitors

A fleet test using Propylene Glycol (PG) based coolant, recycled PG based coolant and PG mixed with ethylene glycol (EG) coolant was conducted using a fleet of employee vehicles. These coolants were all formulated using extended life, silicate free additive technology. This fleet consisted of a wide range of vehicle types and was run to verify the effectiveness of utilizing a PG based coolant across a broad spectrum of vehicle types. The results from this fleet test will be discussed. Results will include coolant analysis, parts inspection and vehicle repair histories. The environmental (toxicological) benefits of such a coolant will also be discussed.
Technical Paper

Extended Life Carboxylate Coolant Compatibility with Other Coolant Technologies - Examining the Data

Previous studies examined the effect of low levels of silicate (∼<75ppm Si) on hot aluminum corrosion protection. The corrosion protection provided by different coolant technologies was evaluated at different silicate levels. The results indicated that small amounts of silicate have a negative effect on the corrosion protection of aluminum. This work will examine these results and evaluate the effectiveness of different laboratory tests for determining coolant “compatibility.” Results will be examined from several bench and fleet tests showing the effect of coolant mixing on the corrosion rates in various environments. The bench test results will include laboratory glassware and dynamic tests that have been used historically to evaluate coolant compatibility. Differences between the test methods will also be evaluated to determine the relevance of each test procedure in light of the fleet observations.
Technical Paper

Heat Exchange Characteristics Of Silicate And Carboxylate-Based Coolants In Air-Cooled Engine Parts

Effective heat transfer is the most important duty of an engine coolant. The heat exchange characteristics of the cooling system are primarily defined by the physical properties of the coolant, the presence of coatings and air resistance. Good heat transfer properties result in lower local temperatures (reducing the risk of corrosion at heat rejecting surfaces) and allow for more efficient engine designs (less coolant is needed to achieve the same amount of heat transfer, therefore, smaller radiators, heater cores and coolant overflow bottles could be used). If a coating is present, it not only interferes with heat transfer by acting as an insulator, but it may also result in hot spots from the uneven heat distribution and induce localized corrosion. This paper will compare the heat exchange characteristics of silicate and carboxylate-based engine coolants by measuring the rate of heat transfer in a heater core exposed to an air current.