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In this work, an artificial neural network (ANN) model based on the experimental data was developed to study the performance of vacuum membrane distillation (VMD) desalination process under different operating parameters such as the feed inlet temperature, the vacuum pressure, the feed flow rate and the feed salt concentration. The proposed model was found to be capable of predicting accurately the unseen data of the VMD desalination process. The correlation coefficient of the overall agreement between the ANN predictions and experimental data was found to be more than 0.994. The calculation value of the coefficient of variation ( CV ) was 0.02622, and there was coincident overlap between the target and the output data from the 3D generalization diagrams. The optimal operating conditions of the VMD process can be obtained from the performance analysis of the ANN model with a maximum permeate flux and an acceptable CV value based on the experiment. [ABSTRACT FROM AUTHOR]

In this work, a novel concept in freeze desalination (FD) was introduced. Nowadays the total liquefied natural gas (LNG) production capacity has reached 290 Mt/year. Its enormous cold energy released from re-gasification can be used in the freeze desalination process to minimize the overall energy consumption. A process of FD on flake ice maker utilizing LNG cold energy was designed and simulated by HYSYS software. An ice bucket on flake ice maker was chosen as seawater crystallizer mainly due to its continuous ice making and removing ice without heat source. A dynamic model of the freezing section has been developed and simulated through gPROMS software. The results show that the consumption of 1 kg equivalent LNG cold energy can obtain about 2 kg of ice melt water. In addition, it is shown that the power consumption of this LNG/FD hybrid process is negligible. [ABSTRACT FROM AUTHOR]

• A system combining thermal desalination and water-lithium bromide absorption cycle. • Three operating modes—water, water-cooling and water-heating—for different seasons. • Greatly improved energy and exergy utilization. • Great operational flexibility in water, cooling and heating production. Water-refrigeration cogeneration systems combining thermal desalination and absorption cycle have been identified as an effective and promising way of utilizing low-grade heat. To take full advantage of the synergy that can be achieved by the combination and overcome the disadvantages of the existing systems, this study proposes and analyzes a multi-function system composed of a single-effect water-lithium bromide absorption heat pump, a single-effect water-lithium bromide absorption refrigeration heat pump and a low-temperature multi-effect evaporation desalination unit. Consuming mainly low-grade heat, the system can operate in at least three modes: water-refrigeration mode for summer, water-only mode for spring/autumn and water-heating mode for winter, thus capable of meeting the requirements of different seasons. The mathematical model is presented and validated, and thermodynamic performance is studied. The results show that all the modes have good energy/exergy performance, as demonstrated in a case study where the energy- and exergy-based coefficients of performance of the absorption unit are 1.60 and 0.62, 1.75 and 0.87, and 1.75 and 1.01 for the three modes, respectively, and the energy saving rates are all as high as 42.7% compared with conventional systems. The proposed system also features great operational flexibility. In water-refrigeration mode, the refrigeration load rate can be regulated from 20% to 100% for a water load rate within 55.2%–110%. In water-heating mode, the heating load rate can be regulated between 0 and a top limit allowed which reaches 256% under a water load rate of 50%, peaks at 459% under 90% and decreases to 358% under 110%. Therefore, the system has good internal synergy, reflected in the whole-year multi-purpose operation, efficient energy utilization, and great operational flexibility. [ABSTRACT FROM AUTHOR]

Large quantities of unstable or even intermittent low-grade heat are released from industrial processes, and a large proportion of them remain unused or used inefficiently. This paper is a proposal and analysis of an energy-efficient and economically feasible way of utilizing the heat to produce fresh water through thermal desalination (TD). An absorption-based thermal energy storage (ATES) unit is introduced to mitigate the mismatch between the unstable heat supply and the relatively stable need of TD. After illustrating the integration logic, a combined ATES and TD system is proposed, and the system configuration and operating modes are introduced. To illustrate the application and the energetic and economic performance of the system, a case study is carried out, where the 100 °C saturated steam intermittently available 7.5 h a day from an industrial process is used as the driving heat source. The results show that the system is energy-efficient, demonstrated by the high coefficient of performance, 1.7, of the ATES subsystem. Being able to run in different modes, the system is applicable to various unstable heat sources. As the first attempt to integrate the ATES into desalination, this study provides a new and effective way of utilizing unstable low-grade heat. [Display omitted] • A combined absorption-based energy storage and thermal desalination system is proposed. • The integration logic, system configuration, operating modes, and case study are presented. • The system is applicable to various unstable low-grade heat sources. • The system is revealed to be energy-efficient and economically feasible. [ABSTRACT FROM AUTHOR]

Large quantities of unstable or even intermittent low-grade heat are released from industrial processes, and a large proportion of them remain unused or used inefficiently. This paper is a proposal and analysis of an energy-efficient and economically feasible way of utilizing the heat to produce fresh water through thermal desalination (TD). An absorption-based thermal energy storage (ATES) unit is introduced to mitigate the mismatch between the unstable heat supply and the relatively stable need of TD. After illustrating the integration logic, a combined ATES and TD system is proposed, and the system configuration and operating modes are introduced. To illustrate the application and the energetic and economic performance of the system, a case study is carried out, where the 100 °C saturated steam intermittently available 7.5 h a day from an industrial process is used as the driving heat source. The results show that the system is energy-efficient, demonstrated by the high coefficient of performance, 1.7, of the ATES subsystem. Being able to run in different modes, the system is applicable to various unstable heat sources. As the first attempt to integrate the ATES into desalination, this study provides a new and effective way of utilizing unstable low-grade heat. [Display omitted] • A combined absorption-based energy storage and thermal desalination system is proposed. • The integration logic, system configuration, operating modes, and case study are presented. • The system is applicable to various unstable low-grade heat sources. • The system is revealed to be energy-efficient and economically feasible. [ABSTRACT FROM AUTHOR]

A graphical method is developed for evaluating the thermodynamic feasibility of combined absorption vapor compression (AVC) and low-temperature multi-effect evaporation (LT-MEE) desalination systems. The method is based on the diagram showing the relationship among the vapor pressure, temperature and concentration of absorbent solution and seawater. Three commonly used absorbent solutions—LiBr-H 2 O, LiCl-H 2 O and CaCl 2 -H 2 O, are taken as examples. A five-step procedure is proposed and three systems—a conventional water-only system, a water-refrigeration cogeneration system and an intermediate vapor absorption water-only system, are analyzed for illustration purpose. Requiring only a small amount of information, the method is suitable to be used in the preliminary planning or design phase of an AVC-MEE system. Besides, the method can also give the values or ranges of several important parameters for the AVC-MEE systems being evaluated to be feasible, thus providing useful information for further investigation. • A graphical method for evaluating the thermodynamic feasibility of AVC-MEE systems is proposed. • The method is based on the vapor pressure diagram of absorbent solution and seawater. • The method is revealed to be effective and easy to apply. • The method can provide useful information for further investigation. [ABSTRACT FROM AUTHOR]