The Experts below are selected from a list of 151374 Experts worldwide ranked by ideXlab platform
S. A. Sherif - One of the best experts on this subject based on the ideXlab platform.
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Optimization of Multistage vapour compression systems using genetic algorithms. Part 1: Vapour compression system model
International Journal of Energy Research, 2001Co-Authors: A. C. West, S. A. SherifAbstract:The vapour compression cycle is the most common type of refrigeration cycle in use today. Most vapour compression systems are simple, having only four major components: a compressor, a condenser, an expansion device and an evaporator. Multistage vapour compression systems are more complex with, for example, extra compressors, aftercoolers, intercoolers, flash tanks and liquid-to-suction heat exchangers. The study performed here considers 121 different configurations operating at condensing and evaporating temperatures that range from −50 to 50°C. The refrigerants used are ammonia, R-22, R-134a, R-152a and R-123. The basis of comparison for the systems is Multistage effectiveness. Multistage effectiveness is a novel term defined as the ratio of the coefficient of performance of a Multistage system to the collective coefficient of performance of an equivalent group of basic single-stage systems operating at the same cooling capacities and evaporating and condensing temperatures. Equivalency here is defined on the basis of achieving the same cooling capacity at their respective temperatures as dictated by the Multistage systems. The vapour compression system model presented here was put through genetic optimization with interesting results. Copyright © 2001 John Wiley & Sons, Ltd.
John H Lienhard - One of the best experts on this subject based on the ideXlab platform.
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Multistage pressure retarded osmosis configurations a unifying framework and thermodynamic analysis
Desalination, 2020Co-Authors: Hyung Won Chung, Jaichander Swaminathan, John H LienhardAbstract:Abstract Pressure-retarded osmosis has enjoyed increasing research interest over the last decade. Recent studies focusing on single-stage PRO designs have raised doubts regarding the long-term economic viability of the technology. While most of the analyses are based on single-stage operation, comprehensive analysis of Multistage PRO which shows promise for better energetic performance is absent. Previous studies on Multistage PRO differ in their design philosophies and performance metrics, leading to an incomplete assessment regarding the potential benefits of multistaging. In this paper, we develop a unifying framework to classify several existing Multistage configurations. In addition, we analyze the Multistage PRO system from a thermodynamic perspective. Among the two major Multistage design strategies, namely interstage pressure control and independent feed inputs to each stage, we found the latter to be more effective towards increasing net power density. In comparison to a single-stage device, a 10-stage system achieves around 9% higher net power density while using the same membrane area.
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split feed counterflow reverse osmosis for brine concentration
Desalination, 2018Co-Authors: Andrew Thomas Bouma, John H LienhardAbstract:Abstract Brine concentration allows for increased recovery ratios in water treatment systems, reduction of waste volumes, and the production of minerals from saline brines. Existing methods of brine concentration, while robust, are often very energy intensive. Better efficiency may be possible using Counterflow Reverse Osmosis (CFRO), a membrane-based, pressure-driven brine concentration technology. The present work develops a model for CFRO. Using this model, a single CFRO module is simulated and its performance characterized. Exergy destruction within a single-stage system is analyzed, which provides insights for configuring and optimizing Multistaged systems. Additionally, a parametric analysis of membrane parameters provides direction for the development of CFRO-specific membranes. Two existing configurations of CFRO are discussed, and compared with a new third configuration, split-feed CFRO, which is presented here for the first time. Split-feed CFRO systems are simulated and optimized to provide guidance for system design. A variety of Multistage systems operating at a range of recovery ratios are simulated, and the results compared are with existing desalination and brine concentration technologies, showing the potential for improved recovery ratios and reduced energy consumption.
A. C. West - One of the best experts on this subject based on the ideXlab platform.
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Optimization of Multistage vapour compression systems using genetic algorithms. Part 1: Vapour compression system model
International Journal of Energy Research, 2001Co-Authors: A. C. West, S. A. SherifAbstract:The vapour compression cycle is the most common type of refrigeration cycle in use today. Most vapour compression systems are simple, having only four major components: a compressor, a condenser, an expansion device and an evaporator. Multistage vapour compression systems are more complex with, for example, extra compressors, aftercoolers, intercoolers, flash tanks and liquid-to-suction heat exchangers. The study performed here considers 121 different configurations operating at condensing and evaporating temperatures that range from −50 to 50°C. The refrigerants used are ammonia, R-22, R-134a, R-152a and R-123. The basis of comparison for the systems is Multistage effectiveness. Multistage effectiveness is a novel term defined as the ratio of the coefficient of performance of a Multistage system to the collective coefficient of performance of an equivalent group of basic single-stage systems operating at the same cooling capacities and evaporating and condensing temperatures. Equivalency here is defined on the basis of achieving the same cooling capacity at their respective temperatures as dictated by the Multistage systems. The vapour compression system model presented here was put through genetic optimization with interesting results. Copyright © 2001 John Wiley & Sons, Ltd.
Théniéj. - One of the best experts on this subject based on the ideXlab platform.
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Step decision rules for Multistage stochastic programming
Automatica, 2008Co-Authors: Théniéj.Abstract:Stochastic programming with step decision rules (SPSDR) aims to produce efficient solutions to Multistage stochastic optimization problems. SPSDR, like plain Multistage Stochastic Programming (SP),...
Hyung Won Chung - One of the best experts on this subject based on the ideXlab platform.
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Multistage pressure retarded osmosis configurations a unifying framework and thermodynamic analysis
Desalination, 2020Co-Authors: Hyung Won Chung, Jaichander Swaminathan, John H LienhardAbstract:Abstract Pressure-retarded osmosis has enjoyed increasing research interest over the last decade. Recent studies focusing on single-stage PRO designs have raised doubts regarding the long-term economic viability of the technology. While most of the analyses are based on single-stage operation, comprehensive analysis of Multistage PRO which shows promise for better energetic performance is absent. Previous studies on Multistage PRO differ in their design philosophies and performance metrics, leading to an incomplete assessment regarding the potential benefits of multistaging. In this paper, we develop a unifying framework to classify several existing Multistage configurations. In addition, we analyze the Multistage PRO system from a thermodynamic perspective. Among the two major Multistage design strategies, namely interstage pressure control and independent feed inputs to each stage, we found the latter to be more effective towards increasing net power density. In comparison to a single-stage device, a 10-stage system achieves around 9% higher net power density while using the same membrane area.
