Robert P. Hesketh

Bubble breakage in pipeline flow

Abstract The rate of bubble breakage in turbulent liquid flow was examined using a population balance containing a bubble breakage model to analyze experimental bubble breakage rate data. The bubble breakage model was based on high-speed motion photography observations of the breakage process in turbulent liquid pipeline flow. The bubble breakage model predicts the number of bubbles formed from a breakage, the size of the bubbles formed and the rate of bubble breakage. Bubble breakage was determined to be binary; bubble breakage size was described by a breakage size function in which unequal bubble sizes had a higher probability of being formed compared to equal bubble sizes; and the breakage rate was assumed to be first order with respect to the number of bubbles of a given size. The value of the breakage rate constant was found to be approximately equal to the frequency of the second mode of oscillation of the maximum stable bubble size in a given turbulent flow.

Combustion of methane and propane in an incipiently fluidized bed

Abstract Temperature and gas concentration experiments have been conducted to determine the temperature at which volatiles begin to combust within the particulate phase of a bubbling fluidized bed. The particulate phase of such a bed was approximated by operating a fluidized bed at incipient fluidization. Gas concentration measurements were made from products of both premixed propane-air and premixed methane-air mixtures. The critical temperatures above which combustion products were observed in the particulate phase were 835°C and 915°C for propane and methane, respectively; below the critical temperature for each fuel-air mixture, combustion was negligible. The propane critical combustion temperature was confirmed from the results of unsteady-state temperature and ignition delay time measurements. These experiments demonstrate that the particulate phase can inhibit the oxidation rate of hydrocarbons.

Methylamine oxidation in a flow reactor: Mechanism and modeling

Abstract The high-temperature oxidation chemistry of methylamine (CH3NH2) has been investigated by elucidating the major reaction paths under flow reactor conditions. A comprehensive detailed chemical-kinetic mechanism is proposed, which is comprised of 350 elementary reactions and 65 reactive species. A set of pyrolysis and oxidation reactions of CH3NH2, combined with the literature HCON reaction chemistry, constitute the proposed mechanism. In addition, the reactions of H-abstraction from both the C- and N-atom centers of CH3NH2, have been incorporated into the mechanism. Good agreement between model predictions and experimental data is obtained over fuel-to-oxygen equivalence ratios ranging from 0.1 to 1.7, for 600–1400 K temperature range, and for subatmospheric (0.01 atm) as well as for atmospheric flow conditions. A reaction path analysis was conducted using the integral averaged reaction rates, and the major reaction pathways were identified. A first-order sensitivity analysis for species CH3NH2, NO, and HCN was performed and the results are compared with the reaction-path analysis.

The effect of volatiles on the combustion of char in a fluidised bed

Abstract The effect of propane on the combustion of char particles in an air-fluidised bed of sand was studied: the objective was to understand how volatiles from coal—simulated by the propane—influence the combustion of char derived from the coal. Each combustion experiment gave the burn-out time of a batch of char particles injected into a hot bed of sand which was fluidised either (a) by air or (b) by a mixture of air and propane. Comparison of experiments (a) and (b) showed that propane reduces the char combustion rate because the propane consumes oxygen within the fluidised bed. The reduction of the char combustion rate, due to the propane, increases with temperature because the propane burns more readily in the bed as the bed temperature increases. It follows that, for highly reactive char, the char combustion rate in the presence of propane may actually decrease as temperature increases: this surprising result suggests that it may not necessarily be beneficial to raise bed temperature to improve carbon combustion efficiency. The propane combustion causes variations of oxygen concentration within the bed. Consequently, the char combustion rate depends upon the circulation pattern of particles. It appears that the char particles are not well mixed: under typical conditions, the char particles are at the top surface of the bed for 30% of the time.

The fluid flow and heat transfer performance of thermoplastic microcapillary films

This paper is concerned with the evaluation of microcapillary films (MCFs) for microfluidic applications. MCFs are a novel type of low cost plastic film containing continuous arrays of microcapillaries that are extruded from thermoplastics where the capillaries within these films can be round or elliptical with diameters between 30 and 500 µm. The hydrodynamic response of MCFs has been investigated in a series of experiments where the flow within each capillary was laminar with Reynolds numbers up to a maximum of 1800. Pressure drop measurements were consistent with standard laminar flow predictions. A set of experiments involving single- and two-flow systems were conducted to characterize the heat transfer performance of MCFs and the efficacy of heat transfer was found to rank close to that of metallic microfluidic devices. The experimental heat transfer measurements were compared to finite-element model predictions for the MCF geometry and the modelling results were in good agreement with experiment. The overall results demonstrate the viable performance of MCFs for low cost application to examples such as flow within capillaries where temperature profiling is required along the length of the capillaries.

The competitive assessment laboratory: introducing engineering design via consumer product benchmarking

In todays quickly changing and increasingly competitive market place, it is imperative that manufacturers keep abreast of the technological advances and design innovations incorporated into competing product lines. The term competitive assessment (or benchmarking) has been coined by manufacturers to describe the process of ethically acquiring, inspecting, analyzing, instrumenting, and testing the product lines of other manufacturers. The Competitive Assessment Laboratory at Rowan University is funded by the National Science Foundation (NSF). In the laboratory, multidisciplinary teams of freshman engineering students from each of the four engineering departments perform each of the above tasks on a consumer product. The laboratory contains a series of consumer appliance test stations featuring PC-based data acquisition systems capable of measuring thermocouple and voltage/current signals. Each station is also equipped with mechanical measurement equipment and portable materials testing equipment. In addition to introducing students to the science and art of design, the Competitive Assessment Laboratory enables the faculty to assess the constantly evolving initial conditions under which the typical engineering student enters his or her course of study.

The Effect of Ambient Temperature, Humidity, and Engine Speed on Idling Emissions from Heavy-Duty Diesel Trucks

A significant fraction of diesel emissions can be attributed to heavy-duty diesel vehicles at idle conditions during which power is being used for systems such as cabin heating or cooling. Although, a variety of low emission, auxiliary power solutions already exist for HDDV trucks, they are not in wide spread use. Moreover, very little work has been done to date to quantify the total emissions and fuel consumption from truck idling. Accordingly, the U.S. Environmental Protection Agency, in collaboration with the New Jersey Department of Transportation, the U.S. Army Aberdeen Test Center, Oak Ridge National Laboratory and Rowan University has initiated a study to quantify the idling emissions and fuel consumption rates for HDDV trucks. Testing was performed in an environmental chamber on five different class 8 trucks with model years ranging from 1990s to 2001. To simulate a wide variety of idling situations, 38 tests were conducted at three different ambient temperatures (0°F, 65°F and 90°F), relative humidity ranging from 22 to 90% and idle speeds from 600 to 1200 RPM. Each test was conducted for approximately 3 hours during which HC, NO x , CO, CO 2 , O 2 and PM emissions were monitored. This paper focuses on the effect of ambient humidity and temperature on HDDV truck idle emissions. The test results show that the emission rates are a function of both the inlet temperature and engine load. For example, a Detroit Diesel engine idling at 600 RPM produced an average NO x emission of 54.8 g/hr for 0° F ambient temperature (with cabin heater activated) to 105 g/hr at 90° F (with cabin air conditioner activated). The effect of humidity was evidenced through a 15 to 20% decrease in NO x concentration when relative humidity increased by a factor of three.

Effect of gas and liquid properties on gas phase dispersion in bubble columns

Abstract The effect of gas and liquid properties on the gas phase dispersion has been investigated in bubble column reactors. Data were obtained in two 3.0 m tall bubble columns (of diameters 0.15 m and 0.25 m) and by varying superficial phase velocities. A novel experimental technique, a quadrupole mass spectrometer, was used to measure the tracer gas concentration. Data analysis was accomplished via a simple axial dispersion model with the inclusion of mass transfer term. Results indicate that an increase in liquid viscosity and decrease in the liquid surface tension leads to a decrease in the gas phase dispersion. Further, the gas properties have no influence on the gas phase dispersion so long as the mass transfer effects are properly accounted for in the model. A hydrodynamic model has been proposed to predict the gas phase dispersion in bubble column reactors. The model distinguishes various bubble fractions present in the column based on the differences in their rise velocities. The model assumes a bimodal distribution of the gas phase, i.e. fast-rising bubbles following a plug-flow behavior and slow-rising bubbles which are being entrained and partially backmixed in the liquid phase. The model has been validated by predicting experimental as well as literature data on gas phase dispersion under various operating conditions. The proposed model is easy to use since it requires few easily obtainable parameters for the prediction of gas phase dispersion, which is essential parameter in the design and upscaling of bubble column reactors.

Evaluation of Emissions and Performance of Diesel Locomotives With B20 Biodiesel Blends: Static Test Results

This paper describes the results to date of a study to quantify the exhaust emissions and performance characteristics of 20% soy methyl ester biodiesel blends (B20) in diesel locomotives representative of a typical commuter transit fleet. Testing is performed with #2 diesel summer blend, #2 diesel winter blend, ultra low sulfur diesel (ULSD) summer blend, ULSD winter blend and B20 blends with each of these fuels. Tests are performed on two different diesel locomotive types to determine the differences in performance and emissions between older and newer locomotive engines when operating on biodiesel blends. Specifically, tests are performed on a GP40FH-2 locomotive equipped with an EMD 16-645 engine manufactured from a 1960’s design and a recently manufactured ALSTOM PL42AC locomotive equipped with an EMD 16-710 engine. The tests are being performed in two phases. The first phase of the project is performed by operating the diesel engines statically (using a load bank) over the full test matrix of 8 fuels. During the static testing phase, brake specific exhaust emissions and fuel consumption are computed for each fuel blend using the line-haul and switcher duty cycles as outlined in the CFR Part 40 Title 92 Federal Test Procedure. Each fuel/locomotive test combination is performed 3 times to ensure repeatability. The second phase of the project consists of mobile in-use emissions testing using a simulated, mobile duty cycle based on actual commuter rail routes. To accurately quantify the exhaust emissions, measurements are made using a Sensors SEMTECH-D mobile emissions analyzer to measure CO, CO2 , NO2 , NO, O2 , and total unburned hydrocarbons (HCs), along with a Wager 6500RR Railroad Opacity Meter. Instantaneous fuel consumption is monitored using two AW Company JV-KG positive displacement flow meters, which measure the supply and return fuel flow rate, respectively.Copyright

Green Engineering: Integration of Green Chemistry, Pollution Prevention, and Risk-Based Considerations

Literature sources on green chemistry and green engineering are numerous. The objective of this chapter is to familiarize readers with some of the green engineering and chemistry concepts, approaches, and tools. In order to do this, the chapter is organized into five sections as follows.