Engine testing at low temperatures

When evaluating fuels and engine lubricants in respect of, for example, fuel economy, high accuracy is required. In any engine testing, the best accuracy and repeatability are obtained with a test engine installed in an engine dynamometer, and not in a car on a chassis dynamometer.
At the Technical Research Centre of Finland, a special cold chamber suitable for engine and transmission component testing was built in 1985. The equipment consists of a 75 m3 cold chamber, a powerful cooling machinery, a computer-controlled engine dynamometer, a hydrostatic propulsion unit and a versatile data acquisition system. This paper describes the structure of the system (cold chamber, cooling machinery and its control system, engine and engine dynamometer installation, instrumentation). Special problems like controlling engine operation point during warm-up, handling of fuels, lubricants and batteries, and measuring fuel consumption without disturbing the fuel system are discussed. The equipment has been used for the determination of the fuel consumption and exhaust emissions of different engines as a function of temperature, and for evaluation of fuels, lubricants and auxiliary heaters. Test results are demonstrated by examples, and accuracy and repeatability are discussed.