@misc{SomhorstOevermannBovoetal., author = {Somhorst, Joop and Oevermann, Michael and Bovo, Mirko and Denbratt, Ingemar}, title = {Evaluation of thermal barrier coatings and surface roughness in a single-cylinder light-duty diesel engine}, series = {International Journal of Engine Research}, volume = {22(2021)}, journal = {International Journal of Engine Research}, issn = {1468-0874}, doi = {10.1177/1468087419875837}, pages = {890 -- 910}, abstract = {The effect of two thermal barrier coatings and their surface roughness on heat transfer, combustion, and emissions has been investigated in a single-cylinder light-duty diesel engine. The evaluated thermal barrier coating materials were plasma-sprayed yttria-stabilized zirconia and hard anodized aluminum, which were applied on the piston top surface. The main tool for the investigation was cylinder pressure analysis of the high-pressure cycle, from which the apparent rate of heat release, indicated efficiency, and heat losses were derived. For verification of the calculated wall heat transfer, the heat flow to the piston cooling oil was measured as well. Application of thermal barrier coatings can influence engine operating conditions like charge temperature and ignition delay. Therefore, extra attention was paid to choosing stable and repeatable engine operating points. The experimental data were modeled using multiple linear regression to isolate the effects of the coatings and of the surface roughness. The results from this study show that high surface roughness leads to increased wall heat losses and a delayed combustion. However, these effects are less pronounced at lower engine loads and in the presence of soot deposits. Both thermal barrier coatings show a reduction of cycle-averaged wall heat losses, but no improvement in indicated efficiency. The surface roughness and thermal barrier coatings had a significant impact on the hydrocarbon emissions, especially for low-load engine operation, while their effect on the other exhaust emissions was relatively small.}, language = {en} } @misc{SomhorstOevermannBovoetal., author = {Somhorst, Joop and Oevermann, Michael and Bovo, Mirko and Denbratt, Ingemar}, title = {A Method to Evaluate the Compression Ratio in IC Engines with Porous Thermal Barrier Coatings}, series = {SAE Technical Papers}, journal = {SAE Technical Papers}, issn = {2688-3627}, doi = {10.4271/2018-01-1778}, abstract = {The compression ratio is an important engine design parameter. It determines to a large extend engine properties like the achievable efficiency, the heat losses from the combustion chamber and the exhaust losses. The same properties are affected by insulation of the combustion chamber. It is therefore especially important to know the compression ratio when doing experiments with thermal barrier coatings (TBC). In case of porous TBCs, the standard methods to measure the compression ratio can give wrong results. When measuring the compression ratio by volume, using a liquid, it is uncertain if the liquid fills the total porous volume of the coating. And for a thermodynamic compression ratio estimation, a model for the heat losses is needed, which is not available when doing experiments with insulation. The subject of this paper is the evaluation of an alternative method to assess the compression ratio. It is based on motored cylinder pressure data like other thermodynamic methods but does not need a model for the heat losses. The validation and application of the method is done with data from experiments involving two types of porous TBCs, performed on a light duty single cylinder diesel engine. The results indicate that the proposed method accurately predicts the compression ratio for porous thermal barrier coatings.}, language = {en} }