This year IMES was exhibiting at SMM in Hamburg for the 11th time. We could welcome many visitors at our stand that were interested in our wide range of highly developed products.
Of course there was a high interest for our new engine analyser EPM-XP plus, which will be available from January 2019, and also for our combustion control module CCM Marine, which has been proven successfully in the market.
But in the centre of attention was also our new front membrane pressure sensor FPS that is specifically designed for the application on dual-fuel engines.
Nowadays the shipping industry and the engine manufacturers are forced to offer alternative propulsion technology due to strict international climate and environmental standards and regulations. For this reason more and more LNG fuelled vessels with pressure controlled gas engines are in operation. In comparison to a diesel engine, the gas engine produces 90% less NOx and 10% less greenhouse gases without exhaust gas treatment.
A pressure controlled engine operating in an optimal range of performance, is more efficiently and keeps emission and fuel consumption at a low level.
New regulation concepts with new combustion procedures only have a small optimal operating window and therefore the application of accurate, robust and durable cylinder pressure sensors on gas-powered engines is essential.
The cylinder pressure sensors transfer pressure signals to the data acquisition unit that evaluates all specific combustion values on each cylinder. The analysed data can be transmitted via CAN-Bus system to the engine control unit which acts to stabilise engine operation.
Based on the above mentioned complexity we developed a new type of sensor.
The front membrane pressure sensor is available with different thread, FPS-01 with M10x1 thread and FPS-02 with M14x1.25 thread. Both have front membranes that make the sensors immune to sooting, i.e. the build-up of combustion deposit on the sensor membrane will be significantly reduced by changeover from gas- to diesel operation particularly on heavy fuel oil operation. The front membrane of the sensor is in contact with the pressure medium and a force element transmits the pressure to a high temperature thin film measuring element. The signal condition unit (SCU) has the function to transduce the resistance measurement into a standard output signal of 4…20 mA and it is connected with the sensor head by a high temperature cable for up to 200°C. The output signal of FPS is temperature compensated for a measuring range of 0…300 bar with a cut-off frequency of 10 kHz. On demand the signal condition unit is also available for further measuring range and also with voltage output.
Additionally the SCU records all important operating data. The user is able to read out the operating hours and the extreme values of Pmax and Tmax for evaluation on its PC by using a bridge interface box (BIF-box) and the IMES PC software. By using a pressure gauge the user can check accuracy of zero point- and span of the sensor and can compare it with the original calibration data.
Due to the very good thermodynamic characteristics of the FPS sensor, cylinder pressure measurements can be made with high precision (< 1% full scale) and this makes it perfectly suitable for engine control. Thermodynamic evaluations on a single cylinder test engine in comparison to a water-cooled piezoelectric reference sensor have confirmed its accuracy. Measurements of 18 bar IMEP@ 1500 rpm have a PMI deviation of 0.5 bar.
Furthermore FPS convince with its long-term stability and constant sensitivity. Designed for a minimum of 16,000 operating hours it is specifically tested for permanent acquisition and evaluation of cylinder pressure sequences, this enables continuously monitoring and evaluation of the engine performance (24h/day; 360 days/year).
The cylinder pressure sensor FPS transmits a continuous pressure signal for the evaluation of the following functions:
We developed an own set-up and connection method for our cylinder pressure sensors and all essential production steps are processed in-house on sophisticated laser welding- and wire bonding machines to meet the highest standards. A special developed high temperature resistant ceramic for up to 400°C provides the basis for the electrical connection of the sensor. The measuring element and the ceramic are connected by wire bonding, as a result the electrical connection withstands temperatures of more than 350°C.
Due to our own platform strategy we are able to manufacture all sensor types according to our customers’ requirements. So the front membrane pressure sensor FPS is not only available with M10x1 - or M14x1.25 thread, the customer can also determine length of sensor sleeve, sensor cable and SCU´s with current- or voltage output signal.
Engine manufacturers are required to fulfil numerous international safety standards, Marine Type Approval is a mandatory requirement for voyage and safety critical devices installed on a ship. Naturally IMES had performed all necessary tests for marine certification and has already applied for the most important type approvals.
The performance of the FPS sensors has not only been proven by internal thermodynamic tests on the IMES test engine, it has been also successfully tested on dual fuel ship’s engines.
The comprehensive evaluation of the acquired data and the transmission to the engine control unit ensure an optimal engine performance and reduce the risk of engine damage. The benefit for the shipping companies is significant. In addition to savings regarding engine maintenance and –repair there are enormous savings regarding fuel consumption.
Also the environmental aspect plays an important role. An optimally adjusted engine operates cleaner, this means improved emission values due to NOx and CO2 reduction which is of great importance to fulfil the different environmental regulations (e.g. IMO TIER III).