Analysis of Lab Reports on Reducing Emissions of Vehicle Power Supplies

Luigi V. Vingo

The City College of New York

 

 

 

 

 

 

Analysis of Lab Reports on Reducing Emissions of Vehicle Power Supplies

For as long as having a car has been for the working class, I have realized polluting the air with emissions is not beneficial to our society. The reports I have chosen are about how to reduce the emissions that vehicles release into the air. All three have the similar goal to increase efficiency, and they do so by utilizing different methods. Some of the examples of the methods used for achieving a more fuel-efficient vehicle are design improvements of components, and changing the chemical composition of the fuel. To compare two types of experiments as they pertain to efficiency of vehicles, physical and simulation, I have chosen three types of experiment. One only physical, one only simulation, and one that compares a physical experiment to validate their generated simulation is accurate.

The first experiment is called “Comparative assessment of a spark ignition engine fueled with gasoline and raw biogas” (Hotta, Sahoo, & Mohanty 2019), I will refer to this as the biogas lab. To do so a single cylinder engine with a compression ratio of 10 was tested with both fuels. Two throttle positions were used, one labeled wide-open throttle and the other part open throttle, rated at 1450 rpm and 1700rpm respectively. The experiment shows an 18% decrease in power with a 66% increase in fuel consumption when the engine was fueled with the biogas instead of gasoline. This substitution of fuel resulted in the biogas emitting 40% less CO into the air than gasoline. (Hotta, 2019)

The next lab report comes from the Society of Automotive Engineers and is titled “An Integrated Cooling System for Hybrid Electric Vehicle Motors: Design and Simulation” (Junkui, Naini, Miller, Wagner, Rizzo, Sebeck. & Shurin, 2018). The lab involves techniques for thermal management of added heat from electric motors.  Keeping the electric motors within their efficiency threshold for temperature is crucial to keep them operating efficiently, insuring a positive return in fuel economy.  The lab states “Regardless of propulsion strategy, efficient cooling of electric motors remains an open challenge” (Junkui, 2018, p.255). The vehicle no matter the design must depend on its onboard thermal management system to remove the heat generated by the motors. Heat management is crucial to ensuring electric motors and the rest of the components stay within their recommended temperature threshold, as well as avoiding catastrophic failure. This experiment focuses on the transmission of heat from an electric motor or any other thermal load to a heat exchanger via heat pipes. Different driving cycles were used to evaluate the cooling performance between convection and no convection on the heat exchanger. The entirety of the experiment was done with the electric motor operating within the range of 55 to 75 degree Celsius. I will refer to this lab as the integrated cooling lab as stated in its title.

The last lab that I chose to analyze is titled “Optimum shape design of a BLDC motor for electric continuous variable valve timing system considering efficiency and torque characteristics” (Baek, 2018).  The focus of the lab is to obtaine the optimum design of a brushless direct current motor or BLDC for use in a continuous variable valve timing system via a simulation. A CVVT is used in the cylinder head of an engine to increase fuel economy and reduce emissions (Baek, 2018). Gains in efficiency through CVVT are essential for any engineer to be able to meet the strict environmental regulations brought on by environmental problems.  Previously a hydraulic fluid was used to change the valve timing, however this technique is limited by a slow response unless within a strict temperature range. In order to design the motor for maximum torque output with minimum cogging torque this lab suggests focusing on the shape of the motor. To accomplish this sampling points were taken using a Latin hypercube sampling to avoid duplicate data points. The data was then analyzed with a computer using finite element analysis and ran through a genetic algorithm to give the dimensions for the most efficient design. The best design from the simulation was made into a physical example to be tested in order to verify that the simulation actually can predict how a BLDC will function. The final results yielded a 16.7% increase in output torque and a 66.2% decrease in cogging torque. When comparing a conventional CVVT to E-CVVT the E-CVVT saw a 39.4% improvement in response time. This lab will be referred to as the BLDC lab.

Rather than having a descriptive abstract that only states the topics covered, all of the lab reports chose the option of having an informative abstract. With this none of the labs I chose failed to include their results in their abstract. The only lab report that failed to mention what the motivation for the experiment was the biogas lab, not stating a motivation in the abstract was surprisingly more engaging because the lack of a narrative leaves the information to be correlated by the reader. The biogas lab is the only experiment lacking any simulation, making it much more straight forward than the other to labs. The other two labs I chose for analysis are, the integrated cooling and brushless motor labs, both left out the implications their lab will have in their respective fields. Another similarity between the integrated cooling and BDLC labs is that both of these labs relied much on simulations. The pattern of how the abstract is formatted most likely depends on the field it was intended to contribute to, before even reading the abstract the reader knows what to expect by looking at the profession of the authors. The Biogas article was written by mechanical and chemical engineers while the other two both came from automotive engineers.

All the key points of a lab report introduction are clearly stated in each lab. Each report gives background and conceptual information, states their significance, relates their lab to other research in their field, and of course states a hypothesis. The most impressive introduction is the lab report on integrated cooling, I found it strange to see results in the introduction, but this was necessary background information. This helped to foreshadow how broad and comprehensive this particular lab was, spanning over multiple agencies utilizing different laboratories.  The lab on integrated cooling had preliminary experiments done by individual engineers, they used preliminary findings from their individual labs to contribute to the final results summarized in this lab report. Also, one attribute that is found in this introduction that was not present in the other introductions was a definitive outline of rest of the report. The lab on BLDC design was the only lab in which the hypothesis was given half way through their introduction. The authors chose instead to conclude their introduction with an outline of their method. This is consistent with other formatting differences from the other two lab reports, those two seem to align with more conventional lab reports. Finally, the biogas lab report gave great conceptual data, although the background information for this report could have been more concise if sources were referenced properly. Being a comparative lab, the Biogas lab does not need to list the exact percentages for the chemical composition of biogas in the introduction. The Biogas lab could have stated that Biogas is made from a varying level of methane and carbon dioxide, then the reference could be looked up to get the exact values of the other ingredients that occur in small quantities.

For the methods of the chosen lab reports only the BLDC design lab’s data set seems not to be replicable. This report lacks specific details on materials and outlining the procedure. The results are stated, but the only evidence given is a small explanation with a table and graph, there is no way to replicate the data by reading this report alone. The part of the report dictated to proving the simulation is valid for improving efficiency more closely follows the guidelines for replication. The BDLC lab gives diagrams, techniques, and steps of the setups regardless if they are simulated or physical. The two reports from automotive engineers went into great detail of their thought process and the physics formulas behind their experiments, an unknown formula could easily be researched. The biogas lab also provided the necessary formulas furthermore it contained a method section greatly specific of procedure, making this by far the easiest lab to replicate from the three I analyzed.

All the labs were generally similar in the beginning of the report. The result section along with the discussion and conclusion, they are not so similar. None of the reports listed their findings in order from most to least significant, they preferred to list them in order of how much effort was contributed to gain the result. Unfortunately, this trait made it difficult to cross reference the reports, this will also make it difficult to extract usable data for research. All three reports did take advantage of graphs to help the reader to interpret their data. Also, all of the labs opted to include their discussion partly with their results even though this is not part of the general outline of a lab report. The labs containing simulations involved another step. The integrated cooling lab needed to run a simulation to test actual airflow situations over their heat pipes. The BLDC design lab made a physical example of the optimum design BLDC for testing the simulation vs the actual performance of the motor but falls short on clearly stating that the simulation is sufficient to test how the final BLDC motor will perform.

For all three reports much of the discussion and analysis was written in the results sections. Any discussion and analysis that was not covered in the missing result and analysis sections was put into a very concise conclusion. Lacking a definitive discussion or analysis section leaves readers questioning the experimenters’ thoughts on their results vs their hypothesis. The BLDC goes into great detail on how to obtain the optimal design using the authors optimal design process, but never mentions again in the conclusion that his entire experiment relies on a simulation. All three of the analyzed labs did although, relate their lab to related work in their field in the conclusion. This technique helps the researcher to be able to have a secondary reference point after reading the abstract. The Biogas lab gives its conclusion with bullet points, while this is informative it is not easy to apply with other concepts. Biogas is extremely stable under high pressure, it can provide more force per spark, this could be taken advantage of even more with a stronger rotating assembly. This connection may not have been made by someone who did not chose to read the article through twice, because it was not restated in the conclusion. The other two labs give their conclusion in language that makes it easy to apply the information learned to future concepts. The author of the BLDC lab states that he wishes to use his optimal design process on other areas where electric motors are utilized i.e. oil and water pumps. The BLDC lab fails to mention in detail its simulation vs physical results. The theme of underrating comparing the simulation to the physical part of the experiment seems to be a huge mistake in validating the use of simulations to replace physical experimentation. That data is some of the most useful and duplicable in the entire report, especially for someone who is researching simulation vs physical experimentation for another field.  The 1.5% difference in efficiency is most likely due to the simulation underestimating friction.

All three labs made contributions towards living in a more fuel-efficient society. All three reports were well written and focus on different areas of the vehicle driveline to improve efficiency. The diffrences in subject matter of each report dictated how each major section was organized and written. The area of highest creativity in an experiment, interpreting the data, is also the place where you see the most variation on how to format the rest of the report. In conclusion, the widest differences and closest similarities were due to a grouping of two of the reports coming from the same field. The mechanical engineers in the biogas report definitely have a different approach to a lab report than the two groups of like-minded automotive engineers who published the other two reports. Overall the labs from the automotive engineers, those being the integrated cooling and BDLC labs, were much more elaborate than the Biogas lab. The Biogas lab was more traditional in following a lab focusing great attention on a small set of data, where the other labs were broad and thought outside the box.

 

 

 

References

Baek, S.-W. (2018). Optimum shape design of a BLDC motor for electric continuous variable

valve timing system considering efficiency and torque characteristics. Microsystem Technologies, 24(11), 4441–4452. https://doi-org.ccny-proxy1.libr.ccny.cuny.edu/10.1007/s00542-018-3991-2

Hotta, S. K., Sahoo, N., & Mohanty, K. (2019). Comparative assessment of a spark ignition

engine fueled with gasoline and raw biogas. Renewable Energy: An International Journal, 134, 1307–1319. https://doi-org.ccny-proxy1.libr.ccny.cuny.edu/10.1016/j.renene.2018.09.049

Junkui Huang, Naini, S. S., Miller, R., Wagner, J., Rizzo, D., Sebeck, K., & Shurin, S. (2018). An

Integrated Cooling System for Hybrid Electric Vehicle Motors: Design and Simulation. SAE International Journal of Commercial Vehicles, 11(5), 255–266. https://doi-org.ccny-proxy1.libr.ccny.cuny.edu/10.4271/2018-01-1108