John R. Reisel

Enhanced double-pass solar air heater with and without porous medium

An energy and exergy study has been done on a double-pass flat-plate solar air collector with and without porous medium embedded inside the lower channel of the collector. Energy conservation equations are used to derive the energy-governing equations for all components of the collector. A second law analysis (the second law of thermodynamics) was carried out to optimize the mass flow rate, which leads to optimization of the energy efficiency. Theoretical results for energy and exergy efficiencies are plotted for the cases of with and without embedded porous medium. Results of this research show that the porous medium embedded inside the lower channel leads to an increase in the thermal efficiency of the collector of more than 30% compared with the case without porous medium, hence showing the importance of employing porous medium in thermal solar collectors. On the other hand, the pressure drop in the air caused by friction with porous medium is not negligible and is also studied here, using the second law analysis.

Assessment of factors impacting success for incoming college engineering students in a summer bridge program

A summer bridge program for incoming engineering and computer science freshmen has been used at the University of Wisconsin-Milwaukee from 2007 to 2010. The primary purpose of this program has been to improve the mathematics course placement for incoming students who initially place into a course below Calculus I on the math placement examination. The students retake the universitys math placement examination after completing the bridge program to determine if they then place into a higher-level mathematics course. If the students improve their math placement, the program is considered successful for that student. The math portion of the bridge program is designed around using the ALEKS software package for targeted, self-guided learning. In the 2007 and 2008 versions of the program, both an on-line version and an on-campus version with additional instruction were offered. In 2009 and 2010, the program was exclusively in an on-campus format, and also featured a required residential component and additional engineering activities for the students. From the results of these four programs, we are able to evaluate the success of the program in its different formats. In addition, data has been collected and analysed regarding the impact of other factors on the programs success. The factors include student preparation before the beginning of the program (as measured by math ACT scores) and the amount of time the student spent working on the material during the program. Better math preparation and the amount of time spent on the program were found to be good indicators of success. Furthermore, the on-campus version of the program is more effective than the on-line version.

Modeling of nitric oxide formation in high-pressure premixed laminar ethane flames

The GRIMECH version 2.11 chemical kinetics mechanism is modified to provide improved predictions of NO concentrations in high-pressure (1 < P < 15), low-temperature (1600 K–1850 K), premixed, flat, laminar, C2H6/O2/N2 flames. The modifications include adding 38 reactions to expand the C2 submechanism and using different reaction rate coefficients for the CH + N2 ↔ HCN + N reaction. The unmodified GRIMECH mechanism significantly underpredicts the NO concentrations in rich flames. In addition, the predictions from the original mechanism are poor qualitatively, particularly at the lower pressures studied. As the prompt-NO mechanism has been shown to be significant in the rich flames in this study, it is expected that the predictive errors of the unmodified mechanism are a result of deficiencies in the modeling surrounding the prompt-NO formation pathway. To account for the underprediction of prompt-NO, a different set of proposed reaction rate coefficients for the CH + N2 ↔ HCN + N are used in the revised model. The expansion of the C2 submechanism reactions enhances the existing C2 chemistry in the original mechanism, which was designed primarily for methane combustion. The modified mechanism provides good agreement with published NO concentration data from the postflame regions of flames from 1 to 9.16 atm. The revised mechanism does continue to underpredict the NO concentrations in 14.6-atm flames, although the predictions are improved qualitatively from the original mechanism at that pressure.

Catalyst Deterioration over the Lifetime of Small Utility Engines

In this paper, the deterioration of catalysts in small, four-stroke, spark-ignition engines is described. The laboratory testing performed followed a proven test method that mimics the lifetime of a small air-cooled utility engine operating under normal field conditions. The engines used were single-cylinder, 6.5-hp, side-valve engines. These engines have a nominal 125-hr lifetime. The effectiveness of the catalysts was determined by testing exhaust emissions before and after the catalyst to determine the catalysts efficiency. This was done several times during the lifetime of the engines to determine the deterioration in the performance of the catalysts at lowering pollutant emissions. Additional testing was performed on the catalysts to determine wear patterns, contamination, and recoverable activity. The results indicate that considerable catalyst deterioration is occurring over the lifetime of the engine. The results reveal that soot buildup, poisons, and active surface loss appear to be the contributing factors to the deterioration. These results were determined after analyzing the exhaust emissions data, scanning electron microscope results analysis, and the impact of regeneration attempts. An ANOVA statistical analysis was performed, and it was determined that the emissions are also impacted, to some degree, by time and the engine itself.

Speciated Hydrocarbon Emissions from Small Utility Engines

ABSTRACT Partially speciated hydrocarbon (HC) emissions data from several small utility engines, as measured by a Fourier Transform Infrared analyzer, are presented. The engines considered have nominal horsepower ratings between 3.7 and 9.3 kW. Both side-valve and overhead-valve engines are studied, and four different fuels are used in the engines. The results indicate that the small HCs present in the exhaust tend to be in the form of either methane or unsatur-ated HCs. Other small alkanes, such as ethane and propane, are present in only relatively small concentrations. In terms of ozone formation potential, the HCs in the form of methane will lead to little ozone, but the distribution of the C2 and C3 species is not ideal from an ozone reduction standpoint. It is also found that the presence of oxygen in the fuels appears to lead to somewhat more complete combustion, although the effects are not large. Finally, the overhead-valve engines appear to have lower HC emissions than side-valve engines, which is primarily due to higher operating A/F ratios and the engine geometry.

Transport Energy Demand Modeling of the United States Using Artificial Neural Networks and Multiple Linear Regressions

In 2009, the transportation sector was the second largest consumer of primary energy in the United States, following the electric power sector and followed by the industrial, residential, and commercial sectors. The pattern of energy use varies by sector. For example, petroleum provides 96% of the energy used for transportation but its share is much less in other sectors. While the United States consumes vast quantities of energy, it has also pledged to cut its greenhouse gas emissions by 2050. In order to assist in planning for future energy needs, the purpose of this study is to develop a model for transport energy demand that incorporates past trends.This paper describes the development of two types of transportation energy models which are able to predict the United States’ future transportation energy-demand. One model uses an artificial neural network technique (a feed-forward multilayer perceptron neural network coupled with back-propagation technique), and the other model uses a multiple linear regression technique. Various independent variables (including GDP, population, oil price, and number of vehicles) are tested.The future transport energy demand can then be forecast based on the application of the growth rate of effective parameters on the models. The future trends of independent variables have been predicted based on the historical data from 1980 using a regression method. Using the forecast of independent variables, the energy demand has been forecasted for period of 2010 to 2030.In terms of the forecasts generated, the models show two different trends despite their performances being at the same level during the model-test period. Although, the results from the regression models show a uniform increase with different slopes corresponding to different models for energy demand in the near future, the results from ANN express no significant change in demand in same time frame. Increased sensitivity of the ANN models to the recent fluctuations caused by the economic recession may be the reason for the differences with the regression models which predict based on the total long-term trends.Although a small increase in the energy demand in the transportation sector of the United States has been predicted by the models, additional factors need to be considered regarding future energy policy. For example, the United States may choose to reduce energy consumption in order to reduce CO2 emissions and meet its national and international commitments, or large increases in fuel efficiency may reduce petroleum demand.Copyright

The Importance of Native In-Country Coordinators for Predictive Awareness of Cultural and Design Details for International Sustainable Engineering Projects

Construction of international sustainable engineering projects in developing communities by student organizations such as Engineers Without Borders involves a minimum of four basic stages: (1) project acquisition based on the communication of the need for the project; (2) travel to the project for site assessment; (3) project design, logistics, and communication of the design with the communities involved; and (4) travel to construct the project. In general, when construction projects are completed locally, there is an ease of communication and travel that shortens all four stages and inevitably the entire process. By comparison, distant locations, language and cultural differences, and exotic politics lengthen these processes, at times creating barriers that prevent the completion of much needed initiatives. An excellent counter to this situation is to utilize a native incountry coordinator who is privy to the local language and dialects, the cultural norms that stupefy outsiders, and is available for site visits to assess progress and answer any design questions the foreign engineers may have. The in-country coordinator predicts the needs of the projects based on his or her background knowledge gained from being native to the area, thus preventing the engineering group from many misunderstandings and perhaps poor design constraints. The fundraising that is required to pay in-country coordinators to ease these processes poses a threat to the ability of student organizations to hire them; however, without their expertise and inherent ability to communicate easily with the community receiving the project, the completed construction and sustainability of the venture is put at risk.

Modelling of energy usage for the refining of ethanol from corn

A mathematical model is developed and presented for calculating the energy usage and costs for the dry milling corn-ethanol production process. The model is formulated into a spreadsheet to facilitate the study of the process. While considering the whole process, the model focuses on the primary energy-consuming cooking and distillation processes. This model is a feed-backwards model, which means process input requirements are calculated based on user-entered values for total annual plant production and various process parameters. Based on these input requirements, the total energy usage and the cost and amount of fuel used during the process are calculated. The accuracy of the model was verified through comparisons between modelling results and published data. This model can be used as a source for investigating other potential energy sources, such as the incorporation of solar energy and wind energy, for use in the ethanol production process.

Effects of Mass Flow Rate and Initial Temperature on Predictions of NO and OH from Detailed Chemical Kinetics Models

Abstract The effects of uncertainty in mass flux and initial temperature on the predictions of NO and OH from a detailed chemical kinetics model are determined. The Sandia steady laminar one-dimensional premixed flame code is used to solve the chemical kinetics model for a series of flames from 1 to 9.16 atm. The model allows the determination of the variation in the predictions of NO and OH concentrations from small changes in mass flow rate and in the initial gas temperature. The mass flow rate and initial gas temperature are two quantities for which experimental uncertainty exists, but the effect of which is not often considered in chemical kinetics modeling. The results indicate that uncertainty in the mass flow rate can significantly affect the quantitative predictions of NO and OH, while the initial gas temperature has little effect on the flame modeling results.

Modeling the Feasibility of Using Solar Thermal Systems for Meeting the Heating Requirements at Corn Ethanol Production Facilities

While ethanol use as a vehicle fuel has been promoted as a renewable alternative to fossil fuels, current production methods of ethanol from corn feedstock rely heavily on the combustion of nonrenewable fuels such as natural gas. Solar thermal systems can provide a renewable energy source for supplying some of the heat required ethanol production. In this paper, a model to analyze the feasibility of using solar thermal energy to reduce natural gas consumption in ethanol production is described and applied. Sites of current ethanol production facilities are used to provide a realistic analysis of the economic feasibility of using solar thermal energy in the ethanol production process. The results show that it is not reasonable to expect to replace all of the natural gas consumption in the heating processes in ethanol production but that application of solar thermal energy can be applied to a specific subsystem such as the preheating of boiler makeup water. Profitability of systems for replacing a fraction of the natural gas is analyzed. It is found that both location and local natural gas prices are important in determining whether to pursue such a project and that solar thermal systems should have long-term profitability.