Oscillations of gas and/or liquid columns in a flow channel can lead to various phenomena such as Stirling cycle heat engines, pulse tube refrigerators, as well as thermally induced gas oscillations like Sondhauss tube and Rijke tube. Although those phenomena may look different from each other, they can be universally described by the concepts of work flow and heat flow. Work flow stands for the acoustic power used in acoustics. Heat flow is the energy flow associated with the hydrodynamic transport of entropy. These energy flows help us to understand the thermoacoustic phenomena and construct acoustical heat engines.The book aims to provide a comprehensive overview of how the oscillations of gas and/or liquid columns make possible the mutual energy conversions between work flow and heat flow through thermal interactions between fluids and channel walls. The thermodynamic aspects of energy flows are highlighted by introducing Lagrangian point of view to explain the thermodynamic cycles that the fluid parcels undergo. The relevant experimental results are provided to verify the theoretical analysis based on basic equations of fluid dynamics.

This updated new edition provides an introduction to the field of thermoacoustics. All of the key aspects of the topic are introduced, with the goal of helping the reader to acquire both an intuitive understanding and the ability to design hardware, build it, and assess its performance. Weaving together intuition, mathematics, and experimental results, this text equips readers with the tools to bridge the fields of thermodynamics and acoustics. At the same time, it remains firmly grounded in experimental results, basing its discussions on the distillation of a body of experiments spanning several decades and countries. The book begins with detailed treatment of the fundamental physical laws that underlie thermoacoustics. It then goes on to discuss key concepts, including simple oscillations, waves, power, and efficiency. The remaining portions of the book delve into more advanced topics and address practical concerns in applications chapters on hardware and measurements. With its careful progression and end-of-chapter exercises, this book will appeal to graduate students in physics and engineering as well as researchers and practitioners in either acoustics or thermodynamics looking to explore the possibilities of thermoacoustics. This revised and expanded second edition has been updated with an eye to modern technology, including computer animations and DeltaEC examples.

Proceedings of the 1991 Cryogenic Engineering Conference held in Huntsville, Alabama, June 11-14, 1991.

This book systematically presents the consolidated findings of the phenomenon of self-organization observed during the onset of thermoacoustic instability using approaches from dynamical systems and complex systems theory. Over the last decade, several complex dynamical states beyond limit cycle oscillations such as quasiperiodicity, frequency-locking, period-n, chaos, strange non-chaos, and intermittency have been discovered in thermoacoustic systems operated in laminar and turbulent flow regimes. During the onset of thermoacoustic instability in turbulent systems, an ordered acoustic field and large coherent vortices emerge from the background of turbulent combustion. This emergence of order from disorder in both temporal and spatiotemporal dynamics is explored in the contexts of synchronization, pattern formation, collective interaction, multifractality, and complex networks. For the past six decades, the spontaneous emergence of large amplitude, self-sustained, tonal oscillations in confined combustion systems, characterized as thermoacoustic instability, has remained one of the most challenging areas of research. The presence of such instabilities continues to hinder the development and deployment of high-performance combustion systems used in power generation and propulsion applications. Even with the advent of sophisticated measurement techniques to aid experimental investigations and vast improvements in computational power necessary to capture flow physics in high fidelity simulations, conventional reductionist approaches have not succeeded in explaining the plethora of dynamical behaviors and the associated complexities that arise in practical combustion systems. As a result, models and theories based on such approaches are limited in their application to mitigate or evade thermoacoustic instabilities, which continue to be among the biggest concerns for engine manufacturers today. This book helps to overcome these limitations by providing appropriate methodologies to deal with nonlinear thermoacoustic oscillations, and by developing control strategies that can mitigate and forewarn thermoacoustic instabilities. The book is also beneficial to scientists and engineers studying the occurrence of several other instabilities, such as flow-induced vibrations, compressor surge, aeroacoustics and aeroelastic instabilities in diverse fluid-mechanical environments, to graduate students who intend to apply dynamical systems and complex systems approach to their areas of research, and to physicists who look for experimental applications of their theoretical findings on nonlinear and complex systems.

Heat transfer enhancement in single-phase and two-phase flow heat exchangers in important in such industrial applications as power generating plant, process and chemical industry, heating, ventilation, air conditioning and refrigeration systems, and the cooling of electronic equipment. Energy savings are of primary importance in the design of such systems, leading to more efficient, environmentally friendly devices. This book provides invaluable information for such purposes.

Developing clean, sustainable energy systems is a pre-eminent issue of our time. Most projections indicate that combustion-based energy conversion systems will continue to be the predominant approach for the majority of our energy usage. Unsteady combustor issues present the key challenge associated with the development of clean, high-efficiency combustion systems such as those used for power generation, heating or propulsion applications. This comprehensive study is unique, treating the subject in a systematic manner. Although this book focuses on unsteady combusting flows, it places particular emphasis on the system dynamics that occur at the intersection of the combustion, fluid mechanics and acoustic disciplines. Individuals with a background in fluid mechanics and combustion will find this book to be an incomparable study that synthesises these fields into a coherent understanding of the intrinsically unsteady processes in combustors.

Proceedings of the 20th International Cryogenic Engineering Conference

The International Conference on Energy and Mechanical Engineering brought together scientists and engineers from energy and engineering sectors to share and compare notes on the latest development in energy science, automation, control and mechanical engineering. This proceedings compiled and selected 156 articles organized into Energy Science and Technology; Mechanical Engineering; Automation and Control Engineering. Amongst them, are the results and development of Government sponsored research projects undertaken both in universities, research institutes, and across industry, reflecting the state-of-art technological know-how of Chinese scientists.

The last two years have witnessed a continuation in the breakthrough shift toward pulse tube cryocoolers for long-life, high-reliability cryocooler applications. One class of pulse tubes that has reached maturity is referred to as “Stirling type” because they are based on the linear Oxford Stirling-cooler type compressor; these generally provide cooling in the 30 to 100 K temperature range and operate at frequencies from 30 to 60 Hz. The other type of pulse tube cooler making great advances is the so-called “Gifford-McMahon type. ” Pulse tube coolers of this type use a G-M type compressor and lower frequency operation to achieve temperatures in the 2 to 10 K temperature range. Nearly a third of this proceedings covers these new developments in the pulse tube arena. Complementing the work on low-temperature pulse tubes is substantial continued progress on rare earth regenerator materials and Gifford-McMahon coolers. These technologies continue to make great progress in opening up the 2 - 4 K market. Also in the commercial sector, continued interest is being shown in the development of long-life, low-cost cryocoolers for the emerging high temperature superconductor electronics market, particularly the cellular telephone base-station market. At higher temperature levels, closed-cycle J-T or throttle-cycle refrigerators are taking advantage of mixed refrigerant gases to achieve low-cost cryocooler systems in the 65 to 80 K temperature range.

Thermoacoustic Combustion Instability Control: Engineering Applications and Computer Codes provides a unique opportunity for researchers, students and engineers to access recent developments from technical, theoretical and engineering perspectives. The book is a compendium of the most recent advances in theoretical and computational modeling and the thermoacoustic instability phenomena associated with multi-dimensional computing methods and recent developments in signal-processing techniques. These include, but are not restricted to a real-time observer, proper orthogonal decomposition (POD), dynamic mode decomposition, Galerkin expansion, empirical mode decomposition, the Lattice Boltzmann method, and associated numerical and analytical approaches. The fundamental physics of thermoacoustic instability occurs in both macro- and micro-scale combustors. Practical methods for alleviating common problems are presented in the book with an analytical approach to arm readers with the tools they need to apply in their own industrial or research setting. Readers will benefit from practicing the worked examples and the training provided on computer coding for combustion technology to achieve useful results and simulations that advance their knowledge and research. - Focuses on applications of theoretical and numerical modes with computer codes relevant to combustion technology - Includes the most recent modeling and analytical developments motivated by empirical experimental observations in a highly visual way - Provides self-contained chapters that include a comprehensive, introductory section that ensures any readers new to this topic are equipped with required technical terms