Calibration of a measurement system for methane pyrolysis detection in rocket nozzles

Within the MERIT project we study the characteristics of methane under conditions found in rocket nozzle cooling channels, i.e. elevated inflow temperature and a high single-sided heat load

Background

In recent years there has been a growing interest in methane as an alternative rocket fuel due to its favorable specific gravity, storage temperature, and thermal stability, in addition to its ability to support In-Situ Resource Utilization. Within the MERIT project we study the characteristics of methane under conditions found in rocket nozzle cooling channels, i.e. elevated inflow temperature and a high single-sided heat load. The MERiT experimental facility has been established at HPT\EGI in cooperation with GKN Aerospace, and as part of ESA's Future Launcher Preparatory Program. The facility enables direct measurement of heat transfer and composition changes in methane under a range of conditions, especially those at the thermo-chemical stability limit of methane. The thermo-catalytic decomposition of methane, also known as pyrolysis, results in the creation of hydrogen and solid carbon in the methane fuel stream. One of the objectives of MERiT project is the in-situ quantification of this pyrolysis effect. To enable such quantification, detailed mapping of the response of different sensors to changes in the gas composition is necessary. From this mapping, correlations between gas composition and sensor outputs can be created, which allow real-time measurements to be taken in the MERiT test facility.

Thesis objectives

The aim of the thesis project is to design and implement a calibration approach for the sensor array implemented in the MERiT test facility, from which the necessary correlations can be obtained. The calibration focuses predominantly on the detection of hydrogen in methane. The sensor array is comprised of ultrasonic, thermal conductivity sensors, and non-dispersive infrared sensors. The calibration is intended to use a gas mixing and analysis setup available at the department of Energy Technology.

The specific objectives of this thesis are:

To perform a literature review on methods of gas analysis and particularly hydrogen measurement in methane fuel
To familiarize with
- The requirements for gas analysis of the MERiT facility as well as existing measurement results
- The preselected sensors and describe their technical specification, applicability, and limitations
- The gas mixing station and gas chromatograph that will be used for experimental investigation
To plan and conduct sensor calibration experiments, including data collection and data processing
To implement pressure and temperature corrections into measurement procedure
To work together with researchers at Energy Technology to validate the measurement system for the operating conditions found in real rocket nozzle cooling channels