Optimized Emission Analysis in Hydrogen Internal Combustion Engines: Fourier Transform Infrared Spectroscopy Innovations and Exhaust Humidity Analysis

Abstract

<div>In today’s landscape, environmental protection and nature conservation have become paramount across industries, spurring the ever-increasing aspect of decarbonization. Regulatory measures in transportation have shifted focus away from combustion engines, making way for electric mobility, particularly in smaller engines. However, larger applications like ships and stationary power generation face limitations, not enabling an analogous shift to electrification. Instead, the emphasis shifted to zero-carbon fuel alternatives such as hydrogen and ammonia. In addition to minimal carbon-containing emissions due to incineration of lubricating oil, hydrogen combustion with air results in nitrogen oxide emissions, still necessitating quantification for engine operation compliance with legal regulations. A commonly used multicomponent exhaust gas analyzer on FTIR principle can suffer from higher volumetric water shares in the exhaust gas of the hydrogen engine, influencing the emission analysis. This concern prompted the development of a new evaluation approach for hydrogen operation, analyzing unique wavelength bands for hydrogen operation while considering the higher volumetric water shares in the exhaust gas of a hydrogen engine and its missing carbonaceous emissions. The method’s capability of providing more credible results for hydrogen-powered engines is demonstrated by assessing the newly introduced hydrogen method through variations of the indicated mean effective pressure, the air–fuel equivalence ratio, and the intake air humidity. Presuming minimal CO<sub>2</sub> emissions, the method allows a more realistic allocation of absorption spectra to other emissions. In addition to investigations on the new hydrogen evaluation method, a model for calculating the volumetric water share in the hydrogen engine’s exhaust gas is presented. By comparing the theoretical to the measured water share, the hydrogen emissions of the engine can be calculated without the need for additional hydrogen slip measurement.</div>