Browsing by Subject "Thermodynamics"
Now showing 1 - 20 of 36
Results Per Page
Sort Options
Item A finite difference study of transient heat transfer involving hydrodynamic variation in the thermal entrance region of a circular tube(Texas Tech University, 1970-08) Kliewer, Raymond M.Not availableItem A Model of high power microwave surface flashover at atmospheric pressures(2012-05) Ford, Patrick; Neuber, Andreas A.; Krompholz, Hermann G.; Krile, John T.High Power Microwave Surface Flashover across a dielectric boundary between a high power microwave source and atmospheric environment can cause significant reflection and attenuation of the incident power, leading to a reduction in source efficacy or damage to sensitive components; therefore, it is important to examine the potential causes and effects of surface flashover in high power microwave systems (such as radar). The development of a finite-difference simulation that models the microwave power response to the surface flashover plasma is presented in this thesis, along with background theory related to microwave breakdown in atmospheric gases. Surface flashover is reproduced in the laboratory using a 2.85 GHz source to produce a 3.18 MW, 3 us pulse at atmospheric pressures that are typical for high altitudes (60 - 400 Torr); the full experimental apparatus is discussed.Item A new cubic equation of state(Texas A&M University, 2004-09-30) Atilhan, MertThermodynamic properties are essential for the design of chemical processes, and they are most useful in the form of an equation of state (EOS). The motivating force of this work is the need for accurate prediction of the phase behavior and thermophysical properties of natural gas for practical engineering applications. This thesis presents a new cubic EOS for pure argon. In this work, a theoretically based EOS represents the PVT behavior of pure fluids. The new equation has its basis in the improved Most General Cubic Equation of State theory and forecasts the behavior of pure molecules over a broad range of fluid densities at both high and low pressures in both single and multiphase regions. With the new EOS, it is possible to make accurate estimations for saturated densities and vapor pressures. The density dependence of the equation results from fitting isotherms of test substances while reproducing the critical point, and enforcing the critical point criteria. The EOS includes analytical functions to fit the calculated temperature dependence of the new EOS parameters.Item A Study of Formation and Dissociation of Gas Hydrate(2012-07-16) Badakhshan Raz, SadeghThe estimation of gas hydrate volume in closed systems such as pipelines during shut-in time has a great industrial importance. A method is presented to estimate the volume of formed or decomposed gas hydrate in closed systems. The method was used to estimate the volume of formed gas hydrate in a gas hydrate crystallizer under different subcoolings of 0.2, 0.3, 0.6 and 4.6 degrees C, and initial pressures of 2000 and 2500 psi. The rate of gas hydrate formation increased with increases in subcooling and initial pressure. The aim of the second part of the study was the evaluation of the formation of gas hydrate and ice phases in a super-cooled methane-water system under the cooling rates of 0.45 and 0.6 degrees C/min, and the initial pressures of 1500, 2000 and 2500 psi, in pure and standard sea water-methane gas systems. The high cooling rate conditions are likely to be present in pipelines or around a wellbore producing from gas hydrate reservoir. Results showed that the initial pressure and the chemical composition of the water had little effect on the ice and gas hydrate formation temperatures, which were in the range of -8 +/- 0.2 degrees C in all the tests using the cooling rate of 0.45 degrees C/min. In contrast, the increase in the cooling rate from 0.45 to 0.6 degrees C/min decreased the ice and gas hydrate formation temperatures from -8 degrees C to -9 degrees C. In all tests, ice formed immediately after the formation of gas hydrate with a time lag less than 2 seconds. Finally, an analytical solution was derived for estimating induced radial and tangential stresses around a wellbore in a gas hydrate reservoir during gas production. Gas production rates between 0.04 to 0.12 Kg of gas per second and production times between 0.33 to 8 years were considered. Increases in production time and production rate induced greater radial and tangential stresses around the wellbore.Item A study of thermal transients involving hydrodynamic variation in the thermal entrance region of a circular tube(Texas Tech University, 1968-06) Kliewer, Raymond M.A study of the induced hydrodynamic flow transient and the imposed thermal transient associated with step increases in wall temperature for laminar gas flow in a clrcular tube is presented. The basic governing equations are derived with property variations taken into account. The governing equations are put into an appropriate form for numerical solution. Problem data are specified using air as the gas, and solutions are obtained for three different step increases in the tube wall temperature. It is determined that the step increase in wall temperature produdes not only a thermal transient but also an induced hydrodynamic transient resulting in a corresponding friction factor transient.Item A surrogate model approach to refinery-wide optimization(Texas Tech University, 2004-08) Slaback, Dale DThe techniques currently used to perform refinery-wide optimization can give results that are inconsistent with the overall objectives of the refinery. A full-scale nonlinear refinery-wide optimization approach can accurately predict the overall refinery optimum, but suffers from a large computational requirement. In this study, a surrogate model approach is applied to the refinery-wide optimization problem. The surrogate model approach to large-scale optimization involves building both detailed and approximate models for all of the processing units in the refinery. The detailed models developed in this study are rigorous first-principles models involving the material and energy balance equations. The surrogate model approach to large-scale optimization can employ approximate models of any form. However, selection of the proper form for the approximate models can greatly increase the efficiency of the optimization problem. In this study, fixed physical property phenomenological models are used as the approximate models. By fixing the values of the stream enthalpies and vapor-liquid equilibrium constants, the total number of equations in the process models is greatly reduced. This choice of approximate model form also guarantees that, at convergence, the results of the detailed and approximate models will be identical. The ASCEND IV modeling language is chosen for creating the detailed and approximate models in this study. This modeling platform provides significant advantages over a standard programming language such as Fortran. In addition to having a graphical user interface, the ASCEND software also contains an integrated solver and optimizer, making implementation of the optimization procedure more straightforward. By combining the models of each unit of the refinery together, a refinery-wide model is created. Using the CONOPT optimization routine in ASCEND, the refinery-wide optimization problem can be solved. The optimization results obtained in this work are consistent with the refinery-wide optimization results presented by Li (2000). For the refinery model created in this study, the surrogate model approach decreased the required solution time by nearly an order of magnitude. An optimization was also performed for a refinery in which some product was recycled back to the crude unit. By adding this recycle stream, the system of equations was made much more complex, with each unit being affected by all others. In this case, a dramatic reduction in the optimization solution time was also observed. The refinery model in this study contains 32 decision variables and 63 constraints. An industrial-scale refinery model would be much larger, perhaps including 150 decision variables. The solution time reduction using the surrogate model approach increases with the number of decision variables. Therefore, it is projected that the time reduction for an industrial-scale refinery model could be substantially larger than for the model used in this study. The speedup obtained using the surrogate model approach would decrease the solution time for refinery-wide optimization from several days to only a few hours. By decreasing the solution time, the surrogate model approach provides a method for performing refinery-wide optimization in an industrial setting.Item Accurate Measurements and Modeling of the PpT Behavior of Pure Substances and Natural Gas-Like Hydrocarbon Mixtures(2012-10-19) Mantilla, IvanThe scale of the energy business today and a favorable and promising economic environment for the production of natural gas, requires study of the thermophysical behavior of fluids: sophisticated experimentation yielding accurate, new volumetric data, and development and improvement of thermodynamic models. This work contains theoretical and experimental contributions in the form of 1) the revision and update of a field model to calculate compressibility factors starting from the gross heating value and the mole fractions of diluents in natural gas mixtures; 2) new reference quality volumetric data, gathered with state of the art techniques such as magnetic suspension densimetry and isochoric phase boundary determinations; 3) a rigorous first-principles uncertainty assessment for density measurements; and 4) a departure technique for the extension of these experimental data for calculating energy functions. These steps provide a complete experimental thermodynamic characterization of fluid samples. A modification of the SGERG model, a standard virial-type model for prediction of compressibility factors of natural gas mixtures, matches predictions from the master GERG-2008 equation of state, using least squares routines coded at NIST. The modification contains new values for parametric constants, such as molecular weights and the universal gas constant, as well as a new set of coefficients. A state-of-the-art high-pressure, single-sinker magnetic suspension densimeter is used to perform density measurements over a wide range of temperatures and pressures. This work contains data on nitrogen, carbon dioxide, and a typical residual gas mixture (95% methane, 4% ethane, and 1% propane). Experimental uncertainty results from a rigorous, first-principles estimation including composition uncertainty effects. Both low- and high-pressure isochoric apparatus are used to perform phase boundary measurements. Isochoric P-T data can determine the phase boundaries. Combined with density measurements, isochoric data provides isochoric densities. Further mathematical treatment, including noxious volume and thermal expansion corrections, and isothermal integration, leads to energy functions and thus to a full thermodynamic characterization.Item An examination of possible reversible combustion at high temperatures and pressures for a reciprocating engine(2009-05-15) Patrawala, Kaushik TanvirConventional combustion processes are known to be highly irreversible processes. The potential to obtain useful work from the fuel is degraded during the combustion process. For example, for a reciprocating internal combustion engine, about 20% or more of the potential work from the fuel is destroyed during the combustion process. This potential work is known as availability (a thermodynamic property). The motivation for the current work was to develop a conceptual model of a set of processes related to reciprocating engines that would eliminate this destruction of availability. One conceptual model, proposed by Keenan, suggested that a preselected set of ?reactants? could be compressed (at constant composition) to a high temperature and pressure. At this high temperature and pressure, the ?reactants? would be in chemical equilibrium. At this point, the ?reactants? would be expanded back to the original volume. The expansion process would consist of a ?shifting? chemical equilibrium such that the composition during expansion would continue to change. At the end of the compression and expansion, net work would be available without destroying any of the work potential of the fuel. The purpose of the current work was to develop a quantitative model of this concept, and to use the model in a series of computations to examine the effects of temperature, pressure, and other parameters on the work production capability of the concept. The concept was studied for eight different fuels for various conditions. In general, the net work output increased as the temperature, pressure and compression ratio increased. For low compression temperatures and pressures, the concept resulted in a small amount of net work produced without destroying any fuel availability. For sufficiently high compression pressure and temperature (e.g., 10 MPa and 6000 K, respectively), however, the thermal efficiency was ~28% for isooctane and was ~40% for hydrogen and methane, for air as the oxidant, an equivalence ratio of 1.0, and a compression ratio of 18. Although the temperatures and pressures considered are well beyond practical values for the materials and designs of today, the general result of the study is that conditions can be identified to eliminate the combustion irreversibility.Item Comparison of the efficiency of a thermo-chemical process to that of a fuel cell process when both involve the same chemical reaction(2009-05-15) Bulusu, Seshu PeriahThis work assesses if a plausible theoretical thermo-chemical scheme can be conceived of, that is capable of extracting work from chemical reactants which can be compared with work produced by a fuel cell, when both processes are supplied with the same reactants. A theoretical process is developed to convert heat liberated from a chemical reaction to work. The hypothetical process is carried over a series of isothermal chemical reactor - heat engine combinations. Conducting the chemical reaction and work extraction over a series of temperature steps minimizes irreversibilities that result from the chemical reaction and heat transfer. Results obtained from the numerical calculations on the scheme confirm that when a large number of reactors-engine combinations are used, irreversibility of the proposed hypothetical reactor-engine combination can be reduced to zero. It is concluded from the results, that the theoretical model is as efficient as a fuel cell when both have the same chemical reaction under identical conditions. The effect of inert gas chemistry on the process has also been observed. It is determined from the results that the chemistry of the inert gas does not affect the proposed process. It is determined from results of a parametric study on the composition of inert gas, that the reduction of inert gas does not significantly improve the efficiency of the proposed process.Item Computer simulation of GTL and various problems in thermodynamics(Texas A&M University, 2005-08-29) Wang, XiaonianThis dissertation intends to provide new tuning techniques for several simple cubic equations of state (EOS) to improve their accuracy in calculating fluid phase equilibrium. It also provides graphical tools to predict some phase equilibrium phenomena from activity coefficient models. Finally, it presents simulation results for a new gas-to-liquids process. Saturation Properties for Fluids: By deriving a new identity linking the heat of vaporization for pure components to the EOS, we are able to find new expressions for the two constants a & b in the EOS. These new expressions then allow tuning of both constants a and b to experimental saturation properties at subcritical temperatures. These new tuning procedures prove effective to the point where the simpler Redlich-Kwong EOS provides better results with our procedure than does the usually superior Peng-Robinson EOS with conventional procedures. Activity Coefficient Models: This dissertation shows the flexibility of four activity coefficient models in the prediction of three fluid phase equilibrium phenomena. From these models we successfully developed new graphs that allow one to identify the presence of any of the three phenomena by visual inspection without performing a complex calculation as seen in current texts. Remote Natural Gas: This dissertation presents simulation results of a new gas-to-liquids process which converts natural gas to liquid transportation fuels. Based on the assumption of adiabatic reactions, our simulation results show that methane conversion increases with higher reaction temperature and longer residence times. Hydrogen can both inhibit methane decomposition and reduce coke formation. The rich components in the natural gas are found to decompose very fast and they have a vast quenching effect on the whole reactions. Recycling of unreacted methane also increases overall methane conversion. Finally, our simulator provides very close prediction of the experimental results from a pilot plant. Thus, we conclude that the simulation work is basically successful in fulfilling the goal of this research.Item Constraints on algal biofuel production(2011-05) Beal, Colin McCartney; Ruoff, Rodney S.; Webber, Michael E., 1971-; Hebner, R. E. (Robert E.); Berberoglu, Halil; Seibert, A F.; King, Carey W.The aspiration for producing algal biofuel is motivated by the desire to replace conventional petroleum fuels, produce fuels domestically, and reduce greenhouse gas emissions. Although, in theory, algae have the potential to produce a large amount of petroleum fuel substitutes and capture carbon emissions, in practice, profitable algal biofuel production has proven quite challenging. This dissertation characterizes the production pathways for producing petroleum fuel substitutes from algae and evaluates constraints on algal biofuel production. Chapter 8 provides a summary of the entire dissertation. The first chapter provides a framework for reporting the production of renewable diesel from algae in a consistent way by using data that are specific and by presenting information with relevant metrics. The second chapter presents a review of analytical tools (i.e., microscopy, spectroscopy, and chromatography) that can be used to analyze the structure and composition of intermediate products in an algal biofuel production pathway. In chapters 3 through 6, the energy return on investment, water intensity, and financial return on investment are presented for three cases: 1) an Experimental Case in which data were measured during five batches of algal biocrude production with a combined processed volume of about 7600 L, 2) a hypothetical Reduced Case that assumes the same energy output as the Experimental Case, with reduced energy and material inputs, and 3) a Highly Productive Case that assumes higher energy outputs than the Experimental Case, with reduced energy and material inputs, similar to the Reduced Case. For all three cases, the second-order energy return on investment was determined to be significantly less than 1, which means that all three cases are energy negative. The water intensity (consumption and withdrawal) for all cases was determined to be much greater than that of conventional petroleum fuels and biofuels produced from non-irrigated crops. The financial return on investment was also found to be significantly less than 1 for all cases, indicating production would be unprofitable. Additionally, it was determined that large-scale algal biofuel production would be constrained by the availability of critical energy and material inputs (e.g., nitrogen and carbon dioxide). The final part of this dissertation presents a first-principles thermodynamic analysis that represents an initial attempt at characterizing the thermodynamic limits for algal biofuel production. In that analysis, the energy, entropy, and exergy is calculated for each intermediate product in the algal biofuel production pathway considered here. Based on the results presented in this body of work, game-changing technology and biotechnology developments are needed for sustainable and profitable algal biofuel production.Item Discrete Lagrange equations for reacting thermofluid systems(2009-05) Hean, Charles Robert, 1960-; Fahrenthold, Eric P.The application of Lagrange's equations to non-equilibrium reacting compressible thermofluid systems yields a modeling methodology for thermofluid dynamics compatible with the discrete energy methods used extensively in other energy domains; examples include mechanical systems simulations and molecular dynamics modeling. The introduction of internal energies as generalized coordinates leads to a thermomechanical model with a simple but general form. A finite element interpolation is used to formulate the ODE model in an ALE reference frame, without reference to any partial differential equations. The formulation is applied to highly nonlinear problems without the use of any time-splitting or shock-tracking methods. The method is verified via the solution of a set of example problems which incorporate a variety of reference frames, both open and closed control volumes, and moving boundaries. The example simulations include transient detonations with complex chemistry, piston-initiated detonations, canonical unstable overdriven detonations, high-resolution induction-zone species evolution within a pulsating hydrogen-air detonation, and the detonation of a solid explosive due to high-velocity impact.Item Effects of EGR, water/N2/CO2 injection and oxygen enrichment on the availability destroyed due to combustion for a range of conditions and fuels(2009-06-02) Sivadas, Hari ShankerThis study was directed at examining the effects of exhaust gas recirculation (EGR), water/N2/CO2 injections and oxygen enrichment on availability destroyed because of combustion in simple systems like those of constant pressure and constant volume. Higher cooled EGR fractions lead to higher availability destruction for reactant temperatures less than 2000 K. The availability destroyed for 40% EGR at 300 K for constant pressure and constant volume combustion was 36% and 33%, respectively. Neglecting the chemical availability in the products, the equivalence ratio and reactant temperature that corresponded to the lowest availability destruction varied from 0.8 to 1.0 and 800 K to 1300 K, respectively, depending on the EGR fraction. The fraction of the reactant availability destroyed increased with the complexity of the fuel. The trends stayed the same for the different EGR fractions for the eight fuels that were analyzed. Higher injected water fractions lead to higher availability destruction for reactant temperatures less than 1000 K. The availability destroyed for a 40% injected water fraction at 300 K for constant pressure combustion was 36%. The product temperature ranged from 2300 K to 450 K at a reactant temperature of 300 K for injected fractions from 0% to 90%. For a 40% injected fraction at a reactant temperature of 300 K, water injection and cooled EGR resulted in the greatest destruction of availability (about 36%) with CO2 injection leading to the least destruction (about 32%). Constant volume combustion destroyed less availability compared to constant pressure combustion at a reactant pressure of 50 kPa. At a higher reactant pressure of 5000 kPa, constant pressure combustion destroyed less availability compared to constant volume combustion for reactant temperatures past 1000 K. Higher fractions of oxygen in the inlet lead to higher product temperatures that lead to lower availability destruction. For 40% oxygen in inlet, the product temperature increased to 2900 K and the availability destroyed dropped to 25% at a reactant temperature of 300 K for constant pressure combustion.Item Energetics: the fundamental thermodynamic parameters of molecular complexation via electrostatic interactions in water(2003) Tobey, Suzanne Lai; Anslyn, Eric V.Item Evolution equations in physical chemistry(2009-05) Michoski, Craig E.; Vasseur, Alexis F.; Stanton, John (John F.); Gamba, Irene M.; Wyatt, Robert E.; Souganidis, Panagiotis E.; Henkelman, GraemeWe analyze a number of systems of evolution equations that arise in the study of physical chemistry. First we discuss the well-posedness of a system of mixing compressible barotropic multicomponent flows. We discuss the regularity of these variational solutions, their existence and uniqueness, and we analyze the emergence of a novel type of entropy that is derived for the system of equations. Next we present a numerical scheme, in the form of a discontinuous Galerkin (DG) finite element method, to model this compressible barotropic multifluid. We find that the DG method provides stable and accurate solutions to our system, and that further, these solutions are energy consistent; which is to say that they satisfy the classical entropy of the system in addition to an additional integral inequality. We discuss the initial-boundary problem and the existence of weak entropy at the boundaries. Next we extend these results to include more complicated transport properties (i.e. mass diffusion), where exotic acoustic and chemical inlets are explicitly shown. We continue by developing a mixed method discontinuous Galerkin finite element method to model quantum hydrodynamic fluids, which emerge in the study of chemical and molecular dynamics. These solutions are solved in the conservation form, or Eulerian frame, and show a notable scale invariance which makes them particularly attractive for high dimensional calculations. Finally we implement a wide class of chemical reactors using an adapted discontinuous Galerkin finite element scheme, where reaction terms are analytically integrated locally in time. We show that these solutions, both in stationary and in flow reactors, show remarkable stability, accuracy and consistency.Item Experimental study of the equation of state of isochorically heated warm dense matter(2007) Dyer, Gilliss McNaughton, 1978-; Ditmire, Todd R.We have performed a series of experiments developing the techniques of volumetric, isochoric heating of matter to high energy density states, and the subsequent probing of the release isentrope. Using ultrafast, ultra intense laser systems with pulse lengths from 100fs - 1ps and pulse energies between 2 J and 100 J, we generated strong secondary radiation, in the form of K[subscript alpha] x-rays and directed proton beams, which we used to rapidly heat a foil sample to temperatures from ~ 1 eV to ~ 25 eV at solid density, thus entering the strongly coupled, partially ionized regime of warm dense matter, in which the equation of state is poorly understood. The first set of experiments examines the possibility of using laser generated K[subscript alpha] x-rays in isochoric heating experiments and concludes that this technique will require the use of higher energies and higher Z materials than were used in this thesis to achieve warm dense matter conditions. In the second set of experiments, we used an ultrafast, lasergenerated proton beam with a temperature of ~ 2 MeV and cutoff energy of ~ 40 MeV to volumetrically and isochorically heat a sample foil to > 20 eV. With singleshot diagnostics, we measured the evolution of the temperature with 3:3 ps resolution over the _rst 35 ps of expansion by streaked optical pyrometry, and measured the evolution of the target expansion over the same timescale with sub-ps resolution by chirped pulse interferometry. In this way we were able to verify the equation of state and ion-balance in the SESAME equation of state tables with a Saha ionization model and distinguish this as more accurate than other, simpler models. This thesis establishes an experimental framework for acquiring equation of state data in the regime of warm dense matter that is distinct and complimentary to that acquired by the techniques of shock heating.Item Fundamental modeling and control of falling film evaporators(Texas Tech University, 2004-05) Stefanov, Zdravko I.Evaporators are a common unit operation that can be found in many industries. The evaporator plant, in the pulp and paper industry provides a major role of regenerating the process chemicals from the fiber line waste liquor. The effectiveness of the recovery, determines the overall mill economy. Consequently, the recovery cycle must be fully operation because it is unacceptable to discard the waste liquor due to its highly negative effect on the surrounding ecosystem. The product of the evaporator plant, the concentrated black liquor serves as a fuel to the recovery boiler. The recovery boiler is a combination of a chemical reactor and a power boiler. The dry solids concentration of the black liquor affects the recovery boiler performance not only from an economical point of view but also for safety reasons. It is known, that if the dry solids concentration of the black liquor falls below a lower limit, there is the possibility of an explosion in the recovery boiler. Evaporation of the waste liquor is usually accomplished in a multiple effect evaporator plant. While there are more than one type of evaporator design, the most modern and efficient design is the falling film plate evaporator. This design is characterized with very high heat transfer rates at small temperature differences and high resistance to scaling due to low residence times. This research has two main objectives. The first is to develop a rigorous distributed parameter model of the falling film evaporator using the fundamental principles of mass, energy, and momentum conservation. The second is to synthesize an effective control structure for the evaporator and the evaporator plant. A bench-scale experiment has shown that one-dimensional distributed model of the evaporator plate is satisfactory to describe the important transfer processes on the plate accurately. Additionally, it was confirmed by experimentation that two different hydrodynamic regimes (turbulent and wavy-laminar) can exist in the multiple effect black liquor evaporator plants. Investigations into simple and advanced control approaches have revealed that the closed-loop performance of a proportional-integral-derivative (PID) controller design in feedback with a single evaporator can provide satisfactory compensation. However, in the case of the entire evaporator plant, the advanced control approach of model-predictive control (MPC) provides better control because the MPC centralized controller can address multiple interactions, input and output constraints, and unmeasured disturbances. This work presents the development of the distributed parameter model and the synthesis of the control structure; and demonstrates the performance of the closed-loop system to measured and unmeasured disturbance and parameter uncertainty.Item High accuracy p-rho-t measurements up to 200 MPa between 200 K and 500 K using a compact single sinker magnetic suspension densimeter for pure and natural gas like mixtures(2009-06-02) Atilhan, MertHighly accurate density data is required for engineering calculations to make property estimations in natural gas custody transfer through pipelines. It is also essential to have accurate pressure-volume-temperature (PVT) data for developing equations of state (EOS). A highly accurate, high pressure and temperature, compact single sinker magnetic suspension densimeter has been used for density measurements. First, the densimeter is calibrated against pure component densities for which very reliable data are available. After validating its performance, the densities of four light natural gas mixtures that do not contain components heavier than hexane and two heavy gas mixtures containing hexane and heavier components having fractions more than 0.2 mole percent were measured. The light mixtures were measured in the temperature range of 250 to 450 K and in the pressure range of 10 to 150 MPa (1450 to 21,750 psi); the heavy mixtures were measured in the range of 270 to 340 K and in the pressure range of 3 to 35 MPa (500 to 5,000 psi). Out of those, the data for only four light natural gas mixtures have been presented in the dissertation due to confidentiality agreements that are still in force. A force transmission error and uncertainty analysis was carried out. The total uncertainty was calculated to be 0.11%. Data calculated in this work is compared with the current industry standard EOS for natural gas systems (AGA8-DC92 EOS) and GERG EOS, which is the most recently developed EOS for natural gas systems. The data measured as a part of this research should be used as reference quality data, either to modify the parameters of AGA8-DC92 EOS and GERG EOS or to develop a more reliable equation of state with wider ranges of pressure and temperature.Item Lifetime performance parameter measurement of a low power closed drift thruster(Texas Tech University, 2004-08) Foster, Gregory WNot availableItem Polymer phase equilibrium calculation of a differential method(Texas Tech University, 1977-05) Khalafi, Seyed AbbasNot available