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Frosting of air-coils is an important factor in the design and operation of air-source heat pumps, heat recovery ventilators, cooling and refrigeration equipment etc. This report presents results from laboratory testing of two brine-cooled air-coils under frosting conditions. The coils have the same number of plane, continuos fins, 4 tube rows with 12 tubes in each row, tube spacing of 50 mm and fin spacing of 3 and 6 mm respectively. The original purpose of the test program was to compare various possible indicators of coil frosting and to analyze the possible effects of different control strategies on coil capacity and the COP of the system (the analysis will be presented in a separate report). Tests involved inlet air temperatures of -7 and +2 degrees Celsius, variation of humidity between 70 and 100 % RH (including simulated rain), velocities in the range 1 to 4 m/s, and specific cooling loads from 50 to 150 W/m2. Test results include variations due to frosting of e.g. cooling capacity, COP, air flow and pressure drop, fan power, air outlet temperature and humidity, coil temperature, frost mass, and frosting time. Results also include the subsequently required defrost time, defrost energy and collected mass of defrost water. The frosting process was interrupted when the air flow had decreased to 30 % of the original value with a non-frosted coil. The results clearly show the advantage of demand controlled defrosting with variations in frosting time between 2 h with high humidity/high specific cooling load up to, for practical purposes, infinite frosting times with low humidity/low specific cooling load. The accumulated frost mass during one frosting cycle varied from less than 0.02 kg/m2 up to approximately 0.4 kg/m2.
The definitive text/reference for students, researchers and practicing engineers This book provides comprehensive coverage on refrigeration systems and applications, ranging from the fundamental principles of thermodynamics to food cooling applications for a wide range of sectoral utilizations. Energy and exergy analyses as well as performance assessments through energy and exergy efficiencies and energetic and exergetic coefficients of performance are explored, and numerous analysis techniques, models, correlations and procedures are introduced with examples and case studies. There are specific sections allocated to environmental impact assessment and sustainable development studies. Also featured are discussions of important recent developments in the field, including those stemming from the author’s pioneering research. Refrigeration is a uniquely positioned multi-disciplinary field encompassing mechanical, chemical, industrial and food engineering, as well as chemistry. Its wide-ranging applications mean that the industry plays a key role in national and international economies. And it continues to be an area of active research, much of it focusing on making the technology as environmentally friendly and sustainable as possible without compromising cost efficiency and effectiveness. This substantially updated and revised edition of the classic text/reference now features two new chapters devoted to renewable-energy-based integrated refrigeration systems and environmental impact/sustainability assessment. All examples and chapter-end problems have been updated as have conversion factors and the thermophysical properties of an array of materials. Provides a solid foundation in the fundamental principles and the practical applications of refrigeration technologies Examines fundamental aspects of thermodynamics, refrigerants, as well as energy and exergy analyses and energy and exergy based performance assessment criteria and approaches Introduces environmental impact assessment methods and sustainability evaluation of refrigeration systems and applications Covers basic and advanced (and hence integrated) refrigeration cycles and systems, as well as a range of novel applications Discusses crucial industrial, technical and operational problems, as well as new performance improvement techniques and tools for better design and analysis Features clear explanations, numerous chapter-end problems and worked-out examples Refrigeration Systems and Applications, Third Edition is an indispensable working resource for researchers and practitioners in the areas of Refrigeration and Air Conditioning. It is also an ideal textbook for graduate and senior undergraduate students in mechanical, chemical, biochemical, industrial and food engineering disciplines.
This book provides a comprehensive source of information on freezing and frozen storage of food. Initial chapters describe the freezing process and provide a fundamental understanding of the thermal and physical processes that occur during freezing. Experts in each stage of the frozen cold chain provide, within dedicated chapters, guidelines and advice on how to freeze food and maintain its quality during storage, transport, retail display and in the home. Individual chapters deal with specific aspects of freezing relevant to the main food commodities: meat, fish, fruit and vegetables. Legislation and new freezing processes are also covered. Frozen Food Science and Technology offers in-depth knowledge of current and emerging refrigeration technologies along the entire frozen food chain, enabling readers to optimise the quality of frozen food products. It is aimed at food scientists, technologists and engineers within the frozen food industry; frozen food retailers; and researchers and students of food science and technology.
The latest edition of the classic book grounded in the fundamentals. It introduces heating, ventilation, and air conditioning starting with basic principles of engineering leading to the latest HVAC design practice. Its engineering approach emphasizes fundamentals and realistic applications. Acknowledging numerous approaches to all engineering problems, the book presents alternate approaches and describes why some approaches work best in specific applications and what compromises are made using each of them. Provides carefully worked examples with step-by-step solutions listing assumptions, reference equations, and supporting material. Incorporates a careful use of easy-to-follow units and conversion factors providing basic mass and energy balances. The third edition of Thermal Environmental Engineering has been updated to reflect current approaches as well as new chapters on energy estimation, air handling system design, and piping system design. Discusses new replacement refrigerants as well as environmental issues. Presents single and multiple zone psychronetric systems; moisture transport in building structures; and the latest topics on indoor air quality and human comfort. An essential reference book for professional mechanical engineers.
This book presents selected peer-reviewed papers from the International Conference on Recent Advancements in Air Conditioning and Refrigeration (RAAR) 2019. The focus is on current research in a very topical area of HVAC technology, which has wide-ranging applications. The topics covered include modern air conditioning and refrigeration practices, environment-friendly refrigerants, high-performance components, computer-assisted design, manufacture, operations and data management, energy-efficient buildings, and application of solar energy to heating and air conditioning. This book is useful for researchers and industry professionals working in the field of heating, air conditioning and refrigeration.
Superhydrophobic surfaces, artificially mimicking lotus leaves, have captured the attention of scientists and engineers over the past few decades. Recent trends have shifted from superhydrophobicity to superominipohobicity, or superamphiphobicity. In addition, dynamic rather than static surface wetting/dewetting properties, which can be triggered by various stimuli, including temperature, pH, magnetic/electric fields, solvents, light exposure etc, have been highly sought after for commercial applications. This book will focus on recent topics related to various stimuli-responsive wetting/dewetting surfaces, and give an overview of the knowledge and concepts of how to design and establish these smart artificial surfaces, which can be used for technical developments in a wide variety research fields.
Comprehensive and unique source integrates the material usually distributed among a half a dozen sources. * Presents a unified approach to modeling of new designs and develops the skills for complex engineering analysis. * Provides industrial insight to the applications of the basic theory developed.