Browse Topic: Antifreeze
Samples of 33% glass filled and unfilled poly(butylene terephthalate) [PBT] and nylon 66 (PA66) were injection molded into bars,which were immersed in common engine and powertrain fluids: antifreeze, motor oil and automatic transmission fluid for 25 days. Fluid uptake was measured at 1, 7, 18, and 25 days by gravimetry. Both PBT samples absorbed 0.2-0.25% antifreeze and 0.05 - 0.10% motor oil and automatic transmission fluid (ATF). Both DSC and DMA analysis showed no disruption of polymer thermal transitions or storage moduli. The glass filled PA66 sample absorbed 2.5% antifreeze and 0.25-0.3% of motor oil and ATF and showed an 80°C reduction in the tan delta maximum on DMA. The unfilled PA66 sample absorbed 7% antifreeze and 0.2-0.3% of motor oil and ATF also showed a tan delta maximum 80°C less than the unexposed control. Creep analysis was conducted on the unfilled nylon sample and compared to a virgin material. The softer antifreeze-exposed sample had the expected higher instantaneous strain; however, it had a much reduced viscoelastic response and less permanent deformation. This behavior was thought to arise from hydrogen bond crosslinking of the chains by the imbibed ethylene glycol.
The heat rejection rates and skin temperatures of a liquid cooled exhaust manifold on a 3.5 L Gasoline Turbocharged Direct Injection (GTDI) engine are determined experimentally using an external cooling circuit, which is capable of controlling the manifold coolant inlet temperature, outlet pressure, and flow rate. The manifold is equipped with a jacket that surrounds the collector region and is cooled with an aqueous solution of ethylene-glycol-based antifreeze to reduce skin temperatures. Results were obtained by sweeping the manifold coolant flow rate from 2.0 to 0.2 gpm at 12 different engine operating points of increasing brake power up to 220 hp. The nominal coolant inlet temperature and outlet pressure were 85 °C and 13 psig, respectively. Data were collected under steady conditions and time averaged. For the majority of operating conditions, the manifold heat rejection rate is shown to be relatively insensitive to changes in manifold coolant flow rate. The manifold cooling jacket is observed to successfully reduce skin temperatures in the collector region. However, away from the cooling jacket, skin temperatures are insensitive to changes in manifold coolant flow rate, but remain below the iron-carbon lower transformation temperature limit near 750 °C.
The air cranking system components, which include the tank, valve, hose, and starter, must be carefully selected to provide the necessary speed to start an engine under the most severe climatic conditions for which the system is intended. Engine cranking loads increase with cold temperatures, therefore, the initial selection of these components, needs to consider low-temperature engine torque requirements. To insure an adequate air cranking system is obtained, it is important that proper test procedures are used for obtaining the cranking load requirements of the engine.
Propylene Glycol (PG) and ethylene glycol (EG) are similar in physical properties and therefore both are good base materials for coolant/antifreeze for heavy duty diesel engines. Propylene glycol and ethylene glycol are different chemically and have much different toxicological profiles. These differences result in the two products having greatly different safety characteristics which affect product labelling, use, and disposal. The differences in regulation for these two types of engine coolants as well as the comparisons of performance in heavy duty fleet on-highway service will be addressed. Results of bench-scale and fleet testing will be shown.
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