Gas turbine total energy vapour compression desalination system

Aly, S.E.

doi:10.1016/s0196-8904(98)00124-1

Cited by 9 publications

(6 citation statements)

References 8 publications

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“…A schematic diagram of the process is shown in Figure 12. The design values chosen for the process are guided by those reported for single stage MVC plants analyzed by Veza [9] and Aly [30] and are listed in Table 3. The inlet pressure to the compressor is taken to be the average of the saturation pressure of seawater at a salinity corresponding to the average of the feed and reject salinity.…”

Section: Mechanical Vapor Compressionmentioning

confidence: 99%

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Entropy Generation Analysis of Desalination Technologies

Mistry

McGovern

Thiel

et al. 2011

Entropy

241

242

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Increasing global demand for fresh water is driving the development and implementation of a wide variety of seawater desalination technologies. Entropy generation analysis, and specifically, Second Law efficiency, is an important tool for illustrating the influence of irreversibilities within a system on the required energy input. When defining Second Law efficiency, the useful exergy output of the system must be properly defined. For desalination systems, this is the minimum least work of separation required to extract a unit of water from a feed stream of a given salinity. In order to evaluate the Second Law efficiency, entropy generation mechanisms present in a wide range of desalination processes are analyzed. In particular, entropy generated in the run down to equilibrium of discharge streams must be considered. Physical models are applied to estimate the magnitude of entropy generation by component and individual processes. These formulations are applied to calculate the total entropy generation in several desalination systems including multiple effect distillation, multistage flash, membrane distillation, mechanical vapor compression, reverse osmosis, and humidification-dehumidification. Within each technology, the relative importance of each source of entropy generation is discussed in order to determine which should be the target of entropy generation minimization. As given here, the correct application of Second Law efficiency shows which systems operate closest to the reversible limit and helps to indicate which systems have the greatest potential for improvement.

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Section: Mechanical Vapor Compressionmentioning

confidence: 99%

“…Substitution of Equations (B.8) and (B.17) into Equation (B.12) yields the entropy generated due to irreversible compression, Equation (30).…”

Section: Appendicesmentioning

confidence: 99%

Entropy Generation Analysis of Desalination Technologies

Mistry

McGovern

Thiel

et al. 2011

Entropy

241

242

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“…System operating conditions used in [39,40] were used in this study (Table 8). The smaller pinch in the evaporator-condenser is due to the high heat transfer coefficients found with phase change compared with conventional flow.…”

Section: Mechanical Vapor Compressionmentioning

confidence: 99%

Entropy Generation of Desalination Powered by Variable Temperature Waste Heat

Warsinger

Mistry

Nayar

et al. 2015

Entropy

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Powering desalination by waste heat is often proposed to mitigate energy consumption and environmental impact; however, thorough technology comparisons are lacking in the literature. This work numerically models the efficiency of six representative desalination technologies powered by waste heat at 50, 70, 90, and 120• C, where applicable. Entropy generation and Second Law efficiency analysis are applied for the systems and their components. The technologies considered are thermal desalination by multistage flash (MSF), multiple effect distillation (MED), multistage vacuum membrane distillation (MSVMD), humidification-dehumidification (HDH), and organic Rankine cycles (ORCs) paired with mechanical technologies of reverse osmosis (RO) and mechanical vapor compression (MVC). The most efficient technology was RO, followed by MED. Performances among MSF, MSVMD, and MVC were similar but the relative performance varied with waste heat temperature or system size. Entropy generation in thermal technologies increases at lower waste heat temperatures largely in the feed or brine portions of the various heat exchangers used. This occurs largely because lower temperatures reduce recovery, increasing the relative flow rates of feed and brine. However, HDH (without extractions) had the reverse trend, only being competitive at lower temperatures. For the mechanical technologies, the energy efficiency only varies with temperature because of the significant losses from the ORC.Entropy 2015, 17 7531

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“…This study shows how different combinations of turbines and technologies affect energy consumption. Another study, conducted in several Middle Eastern cities, investigated different plant arrangements operating from the waste heat of a gas turbine power plant (Aly 1999). In this study, low-temperature thermal vapor compression (LT-TVC) heat pumps were used to boost the gas turbine performance, because of their ability to recover energy in the form of heat.…”

Section: Case Studies Of Energy Conservationmentioning

confidence: 99%

“…In this study, low-temperature thermal vapor compression (LT-TVC) heat pumps were used to boost the gas turbine performance, because of their ability to recover energy in the form of heat. Table 2 compares RO (no hybrid used) energy consumption with four different hybrid combinations (Aly 1999). All four options proved to be better, economically, than SWRO alone.…”

Section: Case Studies Of Energy Conservationmentioning

confidence: 99%

Energy Needs, Consumption and Sources

Younos

Tulou

2009

Journal of Contemporary Water Research &Amp; Education

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E nergy is needed in various stages of desalination. Energy consumption directly affects the cost-effectiveness and feasibility of using desalination technologies for drinking water production. This chapter presents energy types, use, methods of conservation, and the potential use of renewable energy resources for desalination. Some of the information provided in this chapter may not be applicable to today's desalination energy issues. However, the information provides a comparison between costs associated with various energy sources as applied to desalination worldwide, and can be used as a reference for future energy development and use for desalination. Energy Needs and ConsumptionEnergy is needed in various stages of desalination. Desalination technologies use pumps in various stages of desalination, i.e., feedwater intake, treatment process, and discharge of product water and concentrate. Pumps consume a significant amount of energy. RO plants use pumps to pressurize feedwater passing through the membranes. Ion exchange plants use pumps to pass the feedwater over the resin, and use backwash pumps to clean and recharge resin beads. In electrodialysis, pumps pressurize feedwater to generate flow across the surface of the membranes. The amount of energy pumps consume depends on the type of process, the TDS concentration in the feedwater, the capacity of the treatment plant, the temperature of the feedwater, and the location of the plant with respect to the location of the intake water and concentrate disposal site.Each desalination technology is unique in design and mode of operation and it is rather difficult to compare energy consumption for different types of desalination technologies. Table 1 is a generalization of typical energy consumption for various technologies.The energy consumption for reverse osmosis plants depends on the salinity of the feedwater and the recovery rate. Seawater reverse osmosis plants require higher amounts of energy due to the higher osmotic pressure of seawater compared to brackish water reverse osmosis plants. The osmotic pressure is related to the TDS concentration of the feedwater. Electrodialysis plants use electric energy to desalt the water. For electrodialysis, the energy required is directly related to the TDS concentration in the water. Electrodialysis is economical only for brackish waters (TDS < 4000 mg/L). Energy Conservation and RecoveryA system's ability to conserve or recover energy is critical for implementing an economical desalination technology. The section below describes various energy conservation and recovery techniques. Methods of Energy ConservationPelton impulse turbines (PIT) and hydraulic turbochargers (HTC) are the most widely used devices for energy conservation in desalination plants (Manth et al. 2003). Reverse running pumps may be found in older facilities, but these pumps are least effective for energy conservation. Figure 1 shows the integration of a PIT with a reverse osmosis plant. Normally, the motor uses electric energy to drive the feed pum...

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Gas turbine total energy vapour compression desalination system

Cited by 9 publications

References 8 publications

Entropy Generation Analysis of Desalination Technologies

Entropy Generation Analysis of Desalination Technologies

Entropy Generation of Desalination Powered by Variable Temperature Waste Heat

Energy Needs, Consumption and Sources

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