Pressure and Temperature Measurements in a Heavy-Duty Diesel Engine

Abstract: The values measured by the temperature and pressure sensors in the gas exchange system are important input parameters for several engine systems. This report focuses on the measurement and signal analysis of pressure and temperature, obtained at different positions within the intake and exhaust manifolds of a heavy-duty Scania diesel engine. Multiple sensors were placed in the intake and exhaust manifolds after which a series of pressure and temperature measurements were conducted at different engine speeds and loads. The experiments revealed that the sensor location does have a significant impact on the obtained signal. It was discovered that the boost pressure signal should be obtained as far from the charge air opening as possible, preferably in the intake port of cylinder 6. This position gave rise to the highest peak-to-peak pressure amplitude, which is preferable for detecting the valve events. The mean pressure at the different positions in the intake manifold deviated at most XX% from the actual mean pressure. The mean pressure deviations are basically constant over all tested engine speeds and loads, meaning that they are easy to compensate for with an offset. In the exhaust manifold, pressure should be measured at a position where several exhaust pulses converge. These positions were found to generate signals where the exhaust pulses could be detected at all the tested engine speeds and loads. The mean pressure deviations at the different positions in the exhaust manifold did not exceed YY% and were in contrast to the mean intake pressure not completely constant. The sampling frequency for the pressure signals in both the intake and exhaust manifold should be set no lower than ZZ Hz at 2300 rpm, as this could cause loss of relevant pressure data. The temperature measurements revealed that the temperature sensors should be placed at positions in the intake and exhaust manifolds where they are located far from the engine block and where there is a high mass flow of gas, as this decreases the impact of the engine block temperature as well as the sensor’s response time. Due to confidentiality, some of the results and measurements have been removed from this open version of the report. This was done by masking some of the axes in figures as well as by using letters/symbols to replace actual measured values.