Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 42 for “"entropy generation"”.
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Entropy generation in fluid mixing
… illustrate, with simple examples, details of the entropy generation processes that are captured in an overall manner by a control volume analysis. The two situations are parallel mixing flows in a duct and the evolution of a wake in a centrifugal compressor. Results are given for the evolution of …
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Energy Dissipation and Entropy Generation During the Fatigue Degradation: Application to Health Monitoring of Composites
… laminates based on the cumulative information entropy is reported. The cumulative entropy demonstrates a persistent trend of nonlinear damage evolution typically observed in the experimental measures of the damage in composite materials. In this dissertation, a continuum formulation for …
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Entropy generation minimization of a heat and mass exchanger for use in a humidification-dehumidification desalination system
The physical mechanisms of entropy generation in a condenser with high fractions of non-condensable gases are examined using control volume, scaling, and boundary layer techniques, with the aim of defining a criterion for minimum entropy generation rate that is useful in engineering analyses. This …
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Second law analysis of a liquid cooled battery thermal management system for hybrid and electric vehicles
… of this indirect liquid cooled system is the entropy generation in each of the components within the system, as well as a total system analysis. Four main components of the system are the battery module, heat exchanger, pump, and throttle. The battery module coolant tubes and the entire heat …
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The utilization and loss of available energy in aerospace systems
… vehicles. Fundamental principles regarding entropy generation and energy availability are developed, including directly linking entropy generation and maximum range and endurance of a powered aircraft. Theory and application of the energy utilization methodology with allocation of losses and …
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Numerical balancing in a humidification dehumidification desalination system
… These systems are typically inefficient due to entropy generation caused by mismatch between the temperature and humidity profiles in both the humidifier and dehumidifier components. Numerical models are developed for several different systems, and it is shown that for a given system with fixed …
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Strain Energy Density and Thermodynamic Entropy as Prognostic Measures of Crack Initiation in Aluminum
… plastic strain energy density and thermodynamic entropy generation up to crack initiation. Plastic strain energy density and thermodynamic entropy generation are evaluated to investigate whether they would be capable of providing a physical basis for fatigue life and structural risk and …
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Impact of unsteady flow processes on the performance of a high speed axial flow compressor
… of axial blade row spacing on the level of entropy generation and the flow mechanisms that affect stage performance. The rotor shock waves that impinge on the upstream blade row result in shed vortices that convect downstream through the rotor. At the reduced axial spacing, vortices with …
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Thermodynamic design optimisation of an open recuperative twin-shaft solar thermal Brayton cycle with combined or exclusive reheating and intercooling
… the components, thus minimising the cumulative entropy generation rate. The resulting optimal design is related to, and therefore characteristic of, the cycle configuration, since the entropy generation rates in the individual components are interdependent. In this work, optimal design of three …
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Optimisation of feedwater heaters and geothermal preheater in fossil-geothermal hybrid power plant
… of a Rankine cycle with single reheat and regeneration and another model with a geothermal preheater substituting the low-pressure feedwater heater were designed. The Engineering Equations Solver (EES) software was used to perform an analysis of the thermodynamic performance of the two models …
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A study on micro-scale combustion
… is set up. Given this thermal model, entropy generation during microcombustion is formulated, and operating parameters for optimum performance are obtained. Finally, making use of the thermal model and entropy generation, a set of combustion rules is proposed.
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Design and optimization of a humidifier for an HDH system
… on a packed bed humidifier. Non-dimensional entropy generation was shown to have a minimum value for varied mass flow ratio as well as for varied water inlet temperature. At its optimal performance condition, the humidifier built for this thesis has a temperature pinch of 2.8 °C and an …
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Thermodynamic analysis and performance evaluation of PTC receiver with external annular fins
… and 2.30 percent for Re = 20000. Similarly, entropy generation reduced with fins variations. The entropy generation rate decreases with increasing fin length. The smooth absorber tube has the highest entropy generation rate whereas the absorber tube with largest fin length has the lowest. …
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Effect of BLI-Type Inlet Distortion on Turbofan Engine Performance
… efficiency and decrease emissions for the next generation of commercial aircraft. While re-energizing the boundary layer formed over the fuselage of an aircraft has many system level benefits, ingesting the low velocity boundary layer flow through a serpentine inlet into a turbofan engine …
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Second law analysis and optimization of humidification-dehumidification desalination cycles
… It is shown that minimizing the specific entropy generation of the cycle maximizes the gained output ratio (GOR). It is also shown that each cycle has one limiting component that cannot be substantially improved and a second component that should be the target of efforts to minimize …
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Performance investigation of various cold thermal energy storages
… The main source of irreversibility was from entropy generation accompanying phase change, although viscous dissipation losses were included. Energy efficiencies were well over 99% for all cases, while exergy efficiencies ranged from 70% to 92%. By far, the most influential variable was the …
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Experimental investigation of the flow field during combustion in narrow circular ducts
… of the flow tube only near the flame front. Entropy generation from vorticity was negligible when compared with the entropy produced from combustion of methane in oxygen, as it was determined through an application of Crocco’s theorem. This confirmed previous computational studies indicating …
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Thermodynamic analysis of electrodialysis
… can be improved, we first study the sources of entropy generation at different salinities, and locate areas where possible improvements need to be made under different operating conditions. In the second part, we define a fair set of constraints to allow a fair comparison between different …
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Black Holes, Galaxy Clusters and Gravitational Waves
… the Intra Cluster Medium (ICM). We characterise entropy generation and mixing induced by the merger process.
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Theory and simulation of surface effects on intrinsic dissipation
… While surface defects always aid in the entropy generation process, the scattering of phonons from rough surfaces can suppress Akhiezer damping. For the case of (2x1) reconstructed silicon surface, the former dominates and the inverse quality factor (Q^-1) is found to increase with the …
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