Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2015. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 124-127). / With growing energy consumption, current research in the field is focused on improving and developing alternatives for energy storage and conversion. Factors such as efficiency of energy conversion, usability of this converted form of energy, power density, energy density etc. help us in determining the right energy source or conversion technology for any specific application. The main aim of this thesis was to study self-propagating reaction waves as a means of converting chemical energy into electrical energy. We carried out numerical simulations to study these self-propagating reaction wave systems and their heat transfer properties. Our analysis shows that for certain specific system heat transfer properties, self-propagating reaction waves can sometimes lead to superadiabatic temperatures, which are temperatures higher than the predicted adiabatic reaction temperature. Having energy available at higher temperature has advantages in heat harvesting applications such as thermoelectricity and thermophotovoltaics. We calculated the improvement in efficiency of a modified thermophotovoltaics setup, when the input is a reaction wave, operating under superadiabatic conditions. Experimentally, we studied these self-propagating reaction waves by launching I D thermopower waves. We demonstrated improved chemical-to-electrical conversion efficiency of these devices (from about 10-⁴ % to 10-² %) by operating with newer fuels such as sodium azide and sucrose with potassium nitrate on single-walled carbon nanotube-based thermal conduits. The net efficiency of operation of the device was also improved to up to 1% by using external thermoelectric harvesters to capture the heat energy lost via convection and radiation. We proposed a model combining the ID reaction heat and mass balance equations with the theory of excess thermopower to predict the output voltage profiles of thermopower wave devices and extract useful data from the voltage plots obtained experimentally. This model allows us to quantify the impact of the device-to-device variation of the fuel and thermal conduit properties, and can guide us to a better choice of fuel-thermal conduit pairs to improve the efficiency of operation. Finally, we experimentally studied 2D reaction waves. These waves were launched with a nitrocellulose fuel layer atop an aluminum foil thermal conduit. A wave front characteristic, the shape of these wave fronts, was studied as a function of heat loss. Energy released by these reactions was again harvested using external thermoelectrics to convert heat energy into electricity. We demonstrated that such a setup of 2D reaction waves can be used to illuminate a light-emitting diode (LED). / by Sayalee G. Mahajan. / Ph. D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1997. / Includes bibliographical references (p. 359-368). / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2011. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 121-129). / Although protein based therapeutics is the fastest growing sector of the pharmaceutical industry, production costs remain incredibly high and rapid commercialization of new protein drug candidates are not being fully realized due to the presence of many barriers, namely the physical and chemical instabilities of proteins. Of these degradation pathways, protein aggregation is arguably the most common and troubling manifestation of protein instability, occurring in almost all phases of development. Protein aggregates are usually nonnative in structure, may exhibit reduced biological activity, and can remain soluble and/or precipitate from solution. In addition to reducing efficacy, if administered to a patient, aggregates can cause adverse reactions, such as immune response, sensitization, or even anaphylactic shock. Therefore, if even a small amount of aggregates form during formulation or storage, a product can be rendered unacceptable. Moreover, for the practical application of traditional and novel drug delivery techniques, protein based therapeutics must be formulated at relatively high concentrations and must remain stable for extended periods of time. The structural differences among various proteins are so significant, that the application of a universal stabilization strategy has not yet been successful, though the effects of common excipients are generally universal. The current approach toward stabilizing protein drugs against aggregation is by trial-and-error testing of different combinations of cosolutes (e.g. salts, sugars, surfactants, amino acids, etc.) using empirically derived heuristics. While ubiquitously used, this approach is inefficient and does not always enable the discovery of stable protein solution formulations. In response to this major problem, we have developed and tested a new class of excipients that has the potential for wide spread application as a universal stabilizer of protein therapeutics. When compared to other commonly used excipients, our novel excipients offer more than an order of magnitude improvement at suppressing the aggregation of a model protein. As a result, if used in formulations, the shelf life of a protein drug, at room or refrigerated temperatures, may be extended from a few weeks to several months or years. Furthermore, these excipients will likely be useful during production and purification for improving yield and lowering downstream purification costs. / by Curtiss P. Schneider. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1993. / Includes bibliographical references (p. [423]-442). / by Henry Richard Holgate. / Ph.D.

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1932. / Appendix contains numerous pamphlets. / Includes bibliographical references. / by Eugene Chen Koo. / Sc.D.

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1984. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 238-247. / by Robert Adams Ware. / Sc.D.

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1951. / Vita. / Includes bibliographical references (leaves 419-425). / by Donald William Peaceman. / Sc.D.

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1973. / Vita. / Bibliography: leaves 385-389. / Sc.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 269-275). / A framework and code have been developed to simulate fiber and film processes; the code can handle three-dimensional, isothermal, incompressible, creeping flow of a Giesekus fluid with free surfaces at infinite capillary number. The code is an extension of the parallel methods developed by Caola et al. from two- to three-dimensional flows, a restructured and improved version of the three-dimensional code of Phillips based on the subproblem formulation. The free surface motion used is an extension of the axially-constrained finite difference method of Phillips from two to three dimensions; internal domain deformation is upgraded from an elliptic mapping technique, only suitable for two-dimensional geometries, to the treatment of the domain as a fictitious elastic solid that conforms to the free surface, similar to the methods of Cairncross et al. The verification of the code and its utility are tested against the ability to capture experimental behavior in a set of benchmark problems which benefit from its ability to compute fully three-dimensional flow fields. Fluids with a nonzero second normal stress difference in simple shear flow, such as Giesekus fluids, exhibit secondary flows in non-circular, non-annular pipes. The code predicts the fully-developed three-dimensional velocity field in flow of a square duct in agreement with Yue et al. Elastically-driven flow transitions from a two-dimensional, steady flow to a three-dimensional, time periodic flow also motivate the need for three-dimensional solvers, which should be able to capture the onset directly. Flow around a closely-spaced linear periodic array of cylinders in a rectangular channel, a flow studied experimentally by Liu, exhibits this kind of flow transition. Numerical simulations have been conducted in this geometry with the Oldroyd-B model, [beta] = 0.67, wall separation distances between 4-32 radii, and Deborah number 0.1 < De < 2.0. The range of bounding wall edge effects on the flow field is shown to be just under 4 cylinder radii. At De = 2.0, the simulation shows small-magnitude oscillations after coming nearly to steady state, and a small-magnitude overshoot in the primary velocity component near the wall can be observed, similar to the "cat's ears" phenomenon observed by Poole et al. in planar gradual-contraction expansion flow of a viscoelastic fluid. The expected critical Weissenberg number of the flow transition has not yet been reached, but the previous limitation of Phillips at De = 0.7 in fully 3-D simulations of this geometry has been surpassed by over a factor of two and it is yet unknown what limiting De the code can reach with continuation methods. The free surface capability of the code is tested in free extrusion from cylindrical and elliptical dies. The code predicts the correct free surface shape and extrudate swell found in incompressible, inertialess Newtonian free jets from cylindrical capillaries. Extruded elliptical jets of Newtonian fluids (2:1 and 3:2 aspect ratios) were found to increase in area to the same extent as cylindrical jets, showing asymmetric swell to a more circular shape (1.8:1 and 2.8:2 final aspect ratios). When Oldroyd-B or Giesekus fluid jets are simulated, the extrudate swell computed increases greatly as Deborah number or polymer viscosity fraction increases, but the final aspect ratio appears to be insensitive to these parameters (De < 1.0). The total amount of swell (area ratio) appears to be independent of the die shape for the elliptical shapes considered (De < 1.0). In addition to solutions to benchmark problems, this thesis introduces the practice of Lagrangian and discontinuous Galerkin finite element methods used to solve various partial differential equations in three dimensions, including bookkeeping conventions that facilitate the development of parallel and modular solvers. Two discontinuous basis function types, discontinuous linear and mean-slope basis functions (abbreviated DLDG and MSDG), are compared in a three-dimensional linear advection problem; both methods show equivalent (quadratically convergent) accuracy in flows orthogonal to the element surfaces. While the DGMS method runs about twice as fast, the DGDL method has roughly twice the accuracy when flow is not orthogonal to element surfaces, so that the DGDL method is preferred whenever mesh refinement in more than one dimension is required to improve the accuracy. A parallel Poisson equation solver which uses PETSc is presented (the source code is available upon request) as a simple template which highlights the required structures needed in a parallel finite element code. / by David Joseph Adrian. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2011. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 189-197). / Protein based therapeutics hold great promise in the treatment of human diseases and disorders and subsequently, they have become the fastest growing sector of new drugs being developed. Proteins are, however, inherently unstable and the degraded form can be quite harmful if administered to a patient. Of the various degradation pathways, aggregation is one of the most common and a cause for great concern. Aggregation suppressing additives have long been used to stabilize proteins, and they still remain the most viable option for combating this problem. However, the mechanisms by which the most commonly used additives inhibit aggregation still remain a mystery for the most part. It is clear that additive selection and the development of better performing additives will benefit from a more refined understanding of how commonly used additives inhibit or enhance aggregation. Aqueous arginine solutions are widely used to suppress protein aggregation and protein-protein interactions. Attempts have been made to develop cosolvents that are similar to arginine, but more effective at inhibiting aggregation. Therefore, a clear picture of the mechanism by which arginine inhibits protein aggregation is desirable. Baynes and Trout have proposed the design of a novel class of additives called "Neutral Crowder", which does not affect the free energy of isolated protein molecules but selectively increases the free energy of the protein-protein encounter complex. They proposed that arginine can be a "Neutral crowder" as the magnitude of the observed aggregation suppression effect of arginine is quantitatively equivalent to a neutral crowder of its size. On the basis of the results obtained in this thesis, we have been able to show that self-interaction of arginine plays a critical role in the mechanism by which it inhibits aggregation. The preferential interaction between protein and arginine is also influenced by the intrasolvent interactions in aqueous arginine solutions, something that is often overlooked and yet essential to understanding the effect of additives on aggregation. Furthermore, the linking together of arginine clusters into bigger clusters by hydrogen bond accepting counterions enhances its aggregation suppressing ability. According to the "Neutral Crowder" theory, large molecules that have the same concentration on the protein surface as the bulk solution should be effective at inhibiting protein association. However, large molecules naturally tend to be excluded from protein surfaces (e.g. polyethylene glycol) due to steric exclusion. We theorized, though, that if functional groups which tend to preferentially bind to proteins (e.g. guanidinium, urea, etc.) were added to the surface of a large, core structure that the resulting molecule could potentially behave as a neutral crowder. Therefore, creating a neutral crowder molecule requires a balance between attraction and repulsion with respect to the surface of a protein. Choosing a proper balance of interactions allowed us to produce compounds which have been shown to be potent aggregation suppressors, slowing aggregation by an order of magnitude more than the commonly used additives. Such potent aggregation suppressing additives might be useful during production and formulation, as they could improve yield and extend the shelf-life of protein therapeutics. / by Diwakar Shukla. / Ph.D.