Haputhanthri Shehan

Bio: Haputhanthri Shehan is an academic researcher from Ford Motor Company. The author has contributed to research in topics: Gasoline & Combustion. The author has an hindex of 5, co-authored 8 publications receiving 74 citations. Previous affiliations of Haputhanthri Shehan include Texas Tech University.

On-chip gradient generation in 256 microfluidic cell cultures: simulation and experimental validation

Abstract: A microfluidic diffusion diluter was used to create a stable concentration gradient for dose response studies. The microfluidic diffusion diluter used in this study consisted of 128 culture chambers on each side of the main fluidic channel. A calibration method was used to find unknown concentrations with 12% error. Flow rate dependent studies showed that changing the flow rates generated different gradient patterns. Mathematical simulations using COMSOL Multi-physics were performed to validate the experimental data. The experimental data obtained for the flow rate studies agreed with the simulation results. Cells could be loaded into culture chambers using vacuum actuation and cultured for long times under low shear stress. Decreasing the size of the culture chambers resulted in faster gradient formation (20 min). Mass transport into the side channels of the microfluidic diffusion diluter used in this study is an important factor in creating the gradient using diffusional mixing as a function of the distance. To demonstrate the device's utility, an H2O2 gradient was generated while culturing Ramos cells. Cell viability was assayed in the 256 culture chambers, each at a discrete H2O2 concentration. As expected, the cell viability for the high concentration side channels increased (by injecting H2O2) whereas the cell viability in the low concentration side channels decreased along the chip due to diffusional mixing as a function of distance. COMSOL simulations were used to identify the effective concentration of H2O2 for cell viability in each side chamber at 45 min. The gradient effects were confirmed using traditional H2O2 culture experiments. Viability of cells in the microfluidic device under gradient conditions showed a linear relationship with the viability of the traditional culture experiment. Development of the microfluidic device used in this study could be used to study hundreds of concentrations of a compound in a single experiment.

Ammonia and Gasoline Fuel Blends for Internal Combustion Engines

Abstract: Ammonia, when blended with hydro carbon fuels, can be used as a composite fuel to power existing IC engines. Such blends, similar to ethanol and gasoline fuel blends, can be used to commercialize ammonia as an alternative fuel. Feasibility of developing ammonia gasoline liquid fuel blends and the use of ethanol as an emulsifier to enhance the solubility of ammonia in gasoline were studied using a small thermostated vapor liquid equilibrium (VLE) high pressure cell in this research. A larger VLE cell was used to develop identified fuel blends in sufficient quantities for engine dynamo-meter tests. A engine dynamometer equipped with a 2.4L gasoline engine was used to benchmark performance of ammonia fuel blends against standard fuels. Solubility test results proved that ethanol free gasoline is capable of dissolving 4.5% of ammonia on volume basis (23 g/l on mass basis) at 50 psi [344.7 kPa] pressure and 286.65 K temperature in liquid phase. Solubility levels are increased with the use of ethanol. Gasoline with 30% ethanol can retain 18% of ammonia in the liquid phase by volume basis (105 g/l by mass basis) at the same pressure and temperature. Dynamometer results show the ability of new composite fuel blends to produce the same amount of torque and power in the lower rpm limits. At higher rpm levels ammonia rich fuels result in an increased torque and power. Thus it can be concluded that hydrogen energy can be stored as ammonia-gasoline fuel blends and recovered back successfully without any strenuous modification to the existing infrastructure and end user equipment or behavior.Copyright © 2014 by ASME

Ammonia Gasoline-Ethanol/Methanol Tertiary Fuel Blends as an Alternate Automotive Fuel

Abstract: Ammonia and hydrocarbon fuel blends, similar to ethanol and gasoline fuel blends can be used to commercialize ammonia as an alternative fuel. Feasibility of developing ammonia gasoline liquid fuel blends and the use of ethanol and methanol as emulsifiers to enhance the solubility of ammonia in gasoline were studied using thermostated vapor liquid equilibrium (VLE) high pressure cells, in this research. Solubility test results prove that emulsifier free pure gasoline is capable of dissolving 23 g/l of ammonia on mass basis (4.5% of ammonia on volume basis) at 345 kPa pressure and 286.65 K temperature in liquid phase. Solubility level is increased with the use of ethanol and methanol. Gasoline with 10% ethanol can retain 31.7 g/l (5.7% on volume basis) of ammonia in the liquid phase at the same pressure and temperature. Methanol has better emulsifying capabilities. Solubility level of gasoline with 30% methanol is 189.5 g/l (30.0% on volume basis). This paper presents solubility and dynamometer test results of five fuel blends E/M0, E10, M10, M20 and M30. Better performances are observed when the ammonia rich fuels are benchmarked against baseline fuel especially at higher engine speeds.Copyright © 2014 by ASME

Review on ammonia as a potential fuel: from synthesis to economics

Abstract: Ammonia, a molecule that is gaining more interest as a fueling vector, has been considered as a candidate to power transport, produce energy, and support heating applications for decades. However, the particular characteristics of the molecule always made it a chemical with low, if any, benefit once compared to conventional fossil fuels. Still, the current need to decarbonize our economy makes the search of new methods crucial to use chemicals, such as ammonia, that can be produced and employed without incurring in the emission of carbon oxides. Therefore, current efforts in this field are leading scientists, industries, and governments to seriously invest efforts in the development of holistic solutions capable of making ammonia a viable fuel for the transition toward a clean future. On that basis, this review has approached the subject gathering inputs from scientists actively working on the topic. The review starts from the importance of ammonia as an energy vector, moving through all of the steps in the production, distribution, utilization, safety, legal considerations, and economic aspects of the use of such a molecule to support the future energy mix. Fundamentals of combustion and practical cases for the recovery of energy of ammonia are also addressed, thus providing a complete view of what potentially could become a vector of crucial importance to the mitigation of carbon emissions. Different from other works, this review seeks to provide a holistic perspective of ammonia as a chemical that presents benefits and constraints for storing energy from sustainable sources. State-of-the-art knowledge provided by academics actively engaged with the topic at various fronts also enables a clear vision of the progress in each of the branches of ammonia as an energy carrier. Further, the fundamental boundaries of the use of the molecule are expanded to real technical issues for all potential technologies capable of using it for energy purposes, legal barriers that will be faced to achieve its deployment, safety and environmental considerations that impose a critical aspect for acceptance and wellbeing, and economic implications for the use of ammonia across all aspects approached for the production and implementation of this chemical as a fueling source. Herein, this work sets the principles, research, practicalities, and future views of a transition toward a future where ammonia will be a major energy player.

A review on clean ammonia as a potential fuel for power generators

Abstract: This review focuses on the use of renewable ammonia for power generation applications and discusses options to convert industrial-grade generators to run on ammonia fuel. The different methods to produce clean ammonia are also discussed in terms of possible advantages and challenges from socio-economic, energetic and environmental perspectives. The main aim of using clean fuel sources, such as ammonia and hydrogen, is to achieve higher sustainability and low carbon emissions compared to conventional fuels. In addition, the present review comparatively assesses and discusses methods for clean ammonia synthesis based on their technical, economic and environmental performance criteria. Numerous potential strategies to improve the clean ammonia production methods are also explored, namely, liquid-electrolyte based systems, composite-membrane based systems, solid-state electrolyte, ceramic/inorganic proton-conducting solid electrolyte based systems, polymer-membrane based systems, O2 conducting-membrane based systems, and molten salt based electrochemical systems. Furthermore, some potential methods to convert various types of commercially available generators to be able to ammonia are proposed and discussed based on the experimental work carried out in the field.

Concentration gradient generation methods based on microfluidic systems

Abstract: Various concentration gradient generation methods based on microfluidic systems are summarized in this paper. The review covers typical structural characteristics, gradient generation mechanisms, theoretical calculation formulas, applicable scopes, and advantages and disadvantages of these approaches in detail. According to the type of reagents involved, these methods are classified into mono-phase methods and multi-phase methods, both of which can be implemented by alternative protocols, while the latter methods particularly refer to droplet-based platforms. For mono-phase methods, the shearing effect would be presented if there are flowing streams in the gradient generation channel. Therefore, the generation speed of channels with moving liquids is relatively fast, which is suitable for dynamic gradients but accompanied by shearing as well, while channels without flowing streams would avoid shearing but are prone to static gradient generation determined by the low speed. Newly developed droplet-based generation systems could provide isolated droplets to avoid the disturbances from the outside continuous phase, however, they require precise droplet generation and control modules. Thereby the most suitable platform can be chosen according to the specific application, while the advantages of different methods could be combined to evade the defects and improve the precision of a single structure.