Hybrid Technology Research Articles

Experimental study on the load control strategy of ammonia-hydrogen dual-fuel internal combustion engine for hybrid power system

The development of hybrid technology and the use of zero-carbon fuels are effective means to improve energy efficiency and reduce carbon emissions. In this study, the Miller cycle spark ignition engine was used, and four load control strategies of throttle, ammonia-hydrogen ratio, air–fuel ratio, and variable valve timing were used to conduct experimental research on the ammonia-hydrogen engine. The experimental results show that the throttle strategy provides the widest output range, and the BMEP is raised from a minimum of 1 bar to 7.4 bar. The ammonia-hydrogen mixing ratio strategy is suitable for cold start conditions, fully utilizing the good combustion characteristics of hydrogen, and at the same time reducing the amount of hydrogen used in the heat engine process as much as possible. The air–fuel ratio strategy provides the highest thermal efficiency with a maximum BTE approaching 40%. It satisfies the energy-saving demand under the single-point working condition of the engine in the series mode. The variable valve timing strategy can realize switching between BMEP between 3.5 bar and 6.5 bar, and keep BTE above 33%. The valve timing strategy can not only provide a wider load adjustment range but also maintain high thermal efficiency. Finally, combining the effects of the four control strategies and the typical operating modes of the hybrid system, this study suggests that the throttle strategy is suitable for the feed mode, the VVT strategy is suitable for the parallel mode, the ammonia-hydrogen mixture ratio strategy is suitable for the cold start condition, and the air–fuel ratio control is suitable for the series mode.

Desalination Pretreatment Technologies: Current Status and Future Developments

Pretreatment of raw feed water is an essential step for proper functioning of a reverse osmosis (RO) desalination plant as it minimizes the risk of membrane fouling. Conventional pretreatment methods have drawbacks, such as the potential of biofouling, chemical consumption, and carryover. Non-conventional membrane-based pretreatment technologies have emerged as promising alternatives. The present review focuses on recent advances in MF, UF, and NF membrane pretreatment techniques that have been shown to be effective in preventing fouling as well as having low energy consumption. This review also highlights the advantages and disadvantages of polymeric and ceramic membranes. Hybrid technologies, which combine the benefits of conventional and non-conventional methods or different membranes, are also discussed as a potential solution for effective pretreatment. The literature that has been analyzed reveals the challenges associated with RO pretreatment, including the high cost of conventional pretreatment systems, the difficulty of controlling biofouling, and the production of large volumes of wastewater. To address these challenges, sustainable hybrid strategies for ceramic membrane-based systems in RO pretreatment are proposed. These strategies include a thorough assessment of the source water, removal of a wide range of impurities, and a combination of methods such as adsorption and carbon dioxide with a low amount of antiscalants. Furthermore, the suggestion of incorporating renewable energy sources such as solar or wind power can help reduce the environmental impact of the system. A pilot study is also recommended to overcome the difficulties in scaling ceramic systems from laboratory to industrial scale. The review also emphasizes the importance of conducting an effective assessment to suggest a treatment for the brine if needed before being discharged to the environment. By following this framework, sustainable, energy-efficient, and effective solutions can be recommended for pretreatment in desalination systems, which can have significant implications for water scarcity and environmental sustainability.

Internet of Things: A Comprehensive Overview on Protocols, Architectures, Technologies, Simulation Tools, and Future Directions

The Internet of Things (IoT) is a global network of interconnected computing, sensing, and networking devices that can exchange data and information via various network protocols. It can connect numerous smart devices thanks to recent advances in wired, wireless, and hybrid technologies. Lightweight IoT protocols can compensate for IoT devices with restricted hardware characteristics in terms of storage, Central Processing Unit (CPU), energy, etc. Hence, it is critical to identify the optimal communication protocol for system architects. This necessitates an evaluation of next-generation networks with improved characteristics for connectivity. This paper highlights significant wireless and wired IoT technologies and their applications, offering a new categorization for conventional IoT network protocols. It provides an in-depth analysis of IoT communication protocols with detailed technical information about their stacks, limitations, and applications. The study further compares industrial IoT-compliant devices and software simulation tools. Finally, the study provides a summary of the current challenges, along with a broad overview of the future directions to tackle the challenges, in the next IoT generation. This study aims to provide a comprehensive primer on IoT concepts, protocols, and future insights that academics and professionals can use in various contexts.

Interfacial microstructure and mechanical properties of Al/steel joints fabricated via thermo-compensated resistance brazing welding with cold spray Zn interlayer

Achieving the effective joining between Al alloy and stainless steel with a large cross-section was meaningful in the significant industry field. For this, the Al/steel dissimilar bimetal materials were manufactured by a novelty hybrid technology, named thermo-compensated resistance brazing welding. The effect of the single Zn foil and the deposited Zn coatings with cold spray technology on the bonding interface, interfacial microstructure, and mechanical properties of the final Al/steel resultant joints were systematically investigated by the relevant analysis method. The results revealed that the obvious reaction layer with main components of Al(s.s) was formed at the Al/steel joints with the single Zn foil as the interlayer. Meanwhile, the introduction of the Zn interlayer improved the temperature field of the joint, which enhanced the lap-shear load of the weld. Besides, the Zn coating was deposited at the top surface of the 304ss substrate as the interlayer to increase joint performance further. The advantage of the pre-deposition formed a better metallurgical bond between the coating and 304ss. The subsequent lap-shear load of the weld was improved with the increase of the Zn coating thickness. The maximum lap-shear load of the final joints reached 2087.6N with a Zn coating thickness of 500 μm and the interfacial structure of the joint was changed: Al alloy, reaction layer I, Al(s.s) + Al2O3, and 304ss from top to bottom. The main composition was Al(s.s) at the reaction layer I between Al alloy and coating.

Ammonia recovery from municipal wastewater using hybrid NaOH closed-loop membrane contactor and ion exchange system

Water scarcity is affected by population growth and increasing nutrients pollution. This study evaluated the integration of ion exchange-natural activated clinoptilolite zeolite (IEX-NZ) and hollow-fibre liquid–liquid membrane contactor (HF-LLMC) as an innovative and sustainable hybrid technology for ammonia recovery from treated urban wastewaters. The process is based on NaOH closed-loop process to i) ensure the extracted concentration of ammonia from the loaded zeolites and ii) enhance the transport of NH3 through the HF-LLMC. Regeneration of the IEX-NZ provided recoveries up to around 92% using 8% NaOH solution with concentration factors between 30 and 60 and a residual ammonium stream below 1 mg NH4+-N/L. Recovery of NH3 from NaOH solutions was carried out by HF-LLMCs using two different membrane chemistries: polypropylene (PP) and poly (4-methyl-1-pentene) (PMP) (>95%). A 1-D model was developed and used to describe the time evolution of NH3 concentration during the recovery process, to determine its mass transfer coefficient (9.5·107 m3/m2·s) and to quantify the undesired water co-transport (5.0·105 m3/m2·s). In addition, the model was used to analyse the influence of operational parameters on the membrane's permeability to maximise the concentration of the ammonium salts recovered as fertilisers. In this case, the 1-D algorithm was used to identify the needed stages to achieve residual levels of NH3 on the treated streams that promoted the NaOH closed-loop recycling to secure economic feasibility.

The current state of laser technologies in the field of functional coatings

Two main directions in the field of laser radiation application for functional coatings are considered - the application of coatings using purely laser study and the combination of laser and other technologies. The most popular technological lasers used in both directions are identified: gas molecular lasers, diode, fiber, and solid-state lasers. Methods of hardening heat treatment of parts using a laser beam both with and without melting of the material are considered. A method of introducing alloying components of metallic and non-metallic nature into the substrate material using laser technologies is presented. The methods of laser surfacing are given, where the surfacing material is fed into the zone of exposure to laser radiation both in the form of a powder mixture and in the form of a filler wire. Powder mixture is most commonly used as surfacing material, wire is less often used. Technologies of laser-assisted evaporation used in the creation of three-dimensional objects are considered. Hybrid technologies of coating deposition are presented - laser surfacing using a plasma arc and high-frequency heating. It was found out that two types of plasmatrons are used in laser-plasma surfacing - direct and indirect types of action. In addition to hybrid laser surfacing, the method of hybrid laser-assisted evaporation is considered - plasma sputtering, or LAAPS, accompanied by laser heating and allowing to obtain coatings with increased adhesion strength to the substrate surface. The main advantages (the ability to adjust the thickness of the deposited coating layers, reduction of the thermal impact zone) and disadvantages (occurrence of cold microcracks on the surface, formation of pores in the coating) in the application of coatings using laser radiation are considered. The prospects for the development of laser and laser-plasma technologies in the field of functional coatings are analyzed on the example of practical application. The development of these technologies in future is largely due to the elimination of their shortcomings, increasing the efficiency of interaction between laser and plasma technologies.

Passive ecosystem services, juxtaposed with engineered processes, can democratize wastewater treatment

Due to technological, economic and environmental constraints, contemporary treatment plants cannot treat all wastewater. In particular, the very high amount of agricultural and urban runoff to be treated is increasingly concerning, especially with more erratic — and unpredictable — rainfall events. Passive ecosystem services can be combined with engineered processes to create hybrid, locally adapted, inexpensive and sustainable technologies to more feasibly treat runoff and wastewater globally.

A Review of Hybrid Floating Solar Plant Designs

Abstract: The demand for power will have doubled by the year 2050. Solar energy currently meets a small percentage of the world's demand, despite its enormous potential as an eco-friendly method for producing electricity. Utilizing land resources sustainably is one of the challenges. As an alternative, floating PV (FPV) plants on bodies of water, such as a dam, reservoir, canal, etc., are gaining popularity worldwide. This project aims to design a hybrid floating solar system that can produce renewable energy in light of the above. Among the hybrid technologies addressed are FPV & hydro systems, FPV & pumped hydro, FPV & wave energy converter, FPV & solar tree, FPV & tracking, FPV & conventional power, and FPV & hydrogen. The review also summarises the main benefits and drawbacks of hybrid floating solar PV (FPV) systems. The hybrid FPV technologies with hydro and solar energy input were some of the most promising ones for producing power efficiently. The important ideas in this paper advance understanding and could serve as a catalyst for the creation of environmentally friendly, sustainable hybrid floating installations

Energy‐efficient task scheduling and resource management in a cloud environment using optimized hybrid technology

AbstractCloud computing is a significant platform emerging for IT enterprises, business applications, and mobile computing. It is a dynamic environment where efficiently and properly allocating resources in such an environment becomes a tedious task. Most existing approaches cannot guarantee energy‐efficient resource management due to the existence of time‐dependent tasks. Cloud resources consume a huge amount of energy, which may reduce the Makespan of the entire network. The process of appropriate task scheduling may satisfy the user's requirement. Reducing energy consumption by satisfying the user's QoS requirements is essential to ensure each user's service level agreement (SLA). Therefore, to achieve an energy‐efficient and unique task scheduling, a technique for order preference by similarity to ideal solution (TOPSIS) based unique ranking (uRank‐TOPSIS) and a Hybrid state‐action‐reward‐state‐action (SARSA), Reinforcement Learning with Black widow Algorithm (HSRLBA) are proposed in this paper. Here, the task scheduling process is carried out using the uRank‐TOPSIS process by producing a set of unique weights and ranking the alternatives. Also, HSRLBA is used to perform resource allocation, which uses the Black widow Algorithm (BWA) to rapidly converge parallel agents in the SARSA model of RL. The Cloudsim simulator is used for experiments. The efficiency of the proposed framework is measured in terms of Makespan, Task Completion Ratio (TCR), total energy consumption, response time and resource utilization. The proposed uRank‐TOPSIS and HSRLBA achieved an energy consumption of 325 KWh, response time of 15.42 s, Makespan of the 1150 s, TCR of 98% and resource utilization of 92%. The proposed framework maximizes TCR and resource utilization and minimizes the Makespan, energy consumption, and response time.

Novel enhancement of energy distribution for marine hybrid propulsion systems by an advanced variable weight decision model predictive control

Marine hybrid technology is attracting increasing research interest thanks to its power versatility and potential economic advantages. However, its overall quality performance is determined by the energy management strategy. This research deals with a variable weighted decision model predictive control (VWDMPC) for marine hybrid energy management, where the main task is to dynamically weight-tuning and optimally allocate energy to obtain the optimal trade-off in terms of fuel consumption, power performance, and energy allocation. For the sake of enhancing the real-time and adaptability of VWDMPC, we utilize the KKT condition to compress the optimal energy management problem and the weight tuning process in one, which cleverly simplifies the optimization process. Performance experiments are performed on a test bench and a real-time hardware execution platform. Different weighting decision comparison scenarios were designed to evaluate the power performance improvement and equivalent fuel consumption of the proposed VWDMPC and give the best proportional weights (0.33,0.27,0.2,0.2) that take both aspects into account. Moreover, this paper also provides validation and feedback based on the evaluation results, which show that the optimal combination of weights that take into account economy and dynamics ranges from (0.3,0.3,0.2,0.2)-(0.33,0.27,0.2,0.2) based on the radar plot drawn from the performance index parameters.

Hybrid crops, income, and food security of smallholder families: Empirical evidence from poor states of India

This study investigates the impact of adopting hybrid crops (rice and maize) on smallholder farm households' income and food security in two of India's poorest states (Bihar and Uttar Pradesh). We use two-stage endogenous treatment regression and farm household data from a survey by the Cereal Systems Initiative for South Asia during 2010–11. Findings suggest that adopting hybrid crops significantly increases smallholders' household income. Hybrid technology adoption also significantly increases smallholder households' food security. However, our findings indicate that the impact on income and food security is much higher for adopters of hybrid maize than for adopters of hybrid rice. These results show that hybrid crops enhance the welfare of smallholder farm families.

Energy Management Strategies for Hybrid Loaders: Classification, Comparison and Prospect

As one of the effective and crucial ways to achieve the energy saving and emission reduction of loaders, hybrid technology has attracted the attention of many scholars and manufacturers. Selecting an appropriate energy management strategy (EMS) is essential to reduce fuel consumption and emissions for hybrid loaders (HLs). In this paper, firstly, the application status of drivetrain configuration of HLs is presented. Then, the working condition characteristics of loaders are analyzed. On the basis of this, the configurations of HLs are classified, and the features and research status of each configuration are described. Next, taking the energy consumption optimization of HLs as the object, the implementation principle and research progress of the proposed rule strategy and optimization strategy are compared and analyzed, and the differences of existing EMSs and future development challenges are summarized. Finally, combining the advantages of intelligent control and optimal control, the future prospective development direction of EMSs for HLs is considered. The conclusions of the paper can be identified in two points: firstly, although the existing EMSs can effectively optimize the energy consumption of HLs, the dependence of the strategy on the mechanism model and the vehicle parameters can reduce the applicability of the strategy to heterogeneous HLs and the robustness to a complex working condition. Secondly, combining the advantages of intelligent control and optimal control, designing an intelligent EMS not depending on the vehicle analytical model will provide a new method for solving the energy consumption optimization problem of HL.

Magnetically separable laccase-biochar composite enable highly efficient adsorption-degradation of quinolone antibiotics: Immobilization, removal performance and mechanisms

The tremendous potential of hybrid technologies for the elimination of quinolone antibiotics has recently attracted considerable attention. This current work prepared a magnetically modified biochar (MBC) immobilized laccase product named LC-MBC through response surface methodology (RSM), and LC-MBC showed an excellent capacity in the removal of norfloxacin (NOR), enrofloxacin (ENR) and moxifloxacin (MFX) from aqueous solution. The superior pH, thermal, storage and operational stability demonstrated by LC-MBC revealed its potential for sustainable application. The removal efficiencies of LC-MBC in the presence of 1 mM 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) for NOR, ENR and MFX were 93.7 %, 65.4 % and 77.0 % at pH 4 and 40 °C after 48 h reaction, respectively, which were 1.2, 1.3 and 1.3 times higher than those of MBC under the same conditions. The synergistic effect of adsorption by MBC and degradation by laccase dominated the removal of quinolone antibiotics by LC-MBC. Pore-filling, electrostatic, hydrophobic, π-π interactions, surface complexation and hydrogen bonding contributed in the adsorption process. The attacks on the quinolone core and piperazine moiety were involved in the degradation process. This study underscored the possibility of immobilization of laccase on biochar for enhanced remediation of quinolone antibiotics-contaminated wastewater. The proposed physical adsorption-biodegradation system (LC-MBC–ABTS) provided a novel perspective for the efficient and sustainable removal of antibiotics in actual wastewater through combined multi-methods.

Assessment of a hybrid technology for liquid fuel dimethyl aminoethyl azide wastewater treatment

Abstract Dimethyl aminoethyl azide (DMAZ) is a liquid fuel in the space industry. Although this fuel is non-carcinogenic, its wastewater suffers from some hazardous pollutants, such as sodium azide (NaN3). A hybrid process of coagulation–flocculation and chemical reaction with nitrous acid was applied for the wastewater treatment. The Taguchi method was used for the process optimization. Coagulant concentration, rapid mixing intensity, duration time, CAMP number and settlement time were found to be effective parameters for the efficiency of the former process. Turbidity and total suspended solids (TSS) of the wastewater were used to track the removal efficiency in the first stage. The complete removal efficiency was achieved. In the latter process, NaN3 was removed using a reaction with nitrous acid. pH of the wastewater was optimized as the controlling factor in the second process. Biochemical oxygen demand (BOD), chemical oxygen demand (COD) and NaN3 removals of 98.9, 98.2 and 96.3% were obtained under the optimum conditions, respectively. As a result, a reduction of 91.9% in turbidity, 98.5% in TSS, 98.5% in BOD, 98.1% in COD and 96.7% in NaN3 concentration were observed in the output of the wastewater.

Porous chitosan-infused graphitic carbon nitride nanosheets for potential microbicidal and photo-catalytic efficacies

Supply of safe drinking water is a high-risk challenge faced internationally. Hybrid technologies involving nanomaterials can offer possible solutions to this research involving natural biopolymers. Porous chitosan with a high specific surface area has promising properties but its use as a membrane component in water purification is still rarely reported. Graphitic carbon nitride (g-C3N4) is a carbon nitride allotrope with a graphene-like layered structure that gifts unfamiliar physicochemical properties due to the presence of s-triazine fragments. It is a metal-free semiconductor with a band gap of ∼2.7 eV to ∼3.7 eV; which shows better visible light-activated photocatalyst properties. This work aims at synthesizing graphitic carbon nitride–biopolymer composite and exploring its properties in the field of wastewater treatment. The samples were synthesized via a soft chemical process with urea, as the source material. The flake-like morphology is displayed in the microstructural SEM image. The composition of the material was analyzed using EDS. Thermogram shows that the material is stable up to 500 °C and also confirms the formation of graphitic carbon nitride. In XRD spectra the intensity reduction shows the chitosan inclusion at the nitride site. The band gap of the prepared material was identified to be 2.3, 2.4 eV. The structural properties were analyzed using Fourier Transform Infrared Spectrometer and Raman spectroscopy. FTIR spectra and Raman spectra indicate the stretching vibration modes of CN and CN heterocycles and chitosan inclusion in the carbon nitride network. The photocatalytic activity was done in sunlight and a UV lamp with different dyes for doped and undoped g-C3N4. The doped (Porous/Non-porous chitosan) g-C3N4 showed faster dye degradation in sunlight compared to UV light. A biomolecular interaction study was done using Bovine serum albumin. It shows the material interaction with the BSA protein. The anti-microbial activity was performed on the Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli by disk diffusion method, the chitosan doped g-C3N4 showed good inhibitions against bacterial growth. The current work reveals the impact of nanoscale chitosan nanostructures doped on the optical, microstructural, catalytic, and antimicrobial properties of g-C3N4 nanosheets. This work provides new research options for nanocomposite-based photocatalytic nanomaterial g-C3N4 so that the quality of contaminated water could be improved.

Optimal Process Planning for Hybrid Additive and Subtractive Manufacturing

AbstractHybrid manufacturing technology has enabled manufacturers to combine advantages of mainly subtractive and additive manufacturing technologies. A single machine supports producing products with complex geometry, at high quality, and with a high degree of automation. To benefit from these advantages, decisions taken in the process planning stage of such a sophisticated manufacturing system should be optimized. The objective of this paper is to determine the optimal process plan considering both the engineering and manufacturing aspects of the hybrid technology. A comprehensive process planning model is proposed. The model specifies the optimal sequence of additive and subtractive features that minimizes the production cycle time. In addition, the model sets the optimal part orientations such that the time needed for building support structures, performing post-processing and inspection operations, changing cutting tools and printing nozzles, and unclamping the part is minimized. The model is comprehensive as it considers productive and non-productive times, precedence, technological, quality, and manufacturing restrictions imposed on hybrid manufacturing systems. The proposed model is nonlinear; due to this nonlinearity, the model is intractable. A linearization scheme is applied to formulate an equivalent linear model that is solvable to optimality by commercial solvers. Case studies on test and industrial parts are provided to evaluate the computational performance of the proposed model. Integrating the proposed model in hybrid manufacturing (HM) systems ensures adopting the HM technology in its optimal direction. HM technology is an enabler of establishing a smart manufacturing system which is one of the pillars of Industry 4.0.

Multi-Method Diagnosis of Histopathological Images for Early Detection of Breast Cancer Based on Hybrid and Deep Learning

Breast cancer (BC) is a type of cancer suffered by adult females worldwide. A late diagnosis of BC leads to death, so early diagnosis is essential for saving lives. There are many methods of diagnosing BC, including surgical open biopsy (SOB), which however constitutes an intense workload for pathologists to follow SOB and additionally takes a long time. Therefore, artificial intelligence systems can help by accurately diagnosing BC earlier; it is a tool that can assist doctors in making sound diagnostic decisions. In this study, two proposed approaches were applied, each with two systems, to diagnose BC in a dataset with magnification factors (MF): 40×, 100×, 200×, and 400×. The first proposed method is a hybrid technology between CNN (AlexNet and GoogLeNet) models that extracts features and classify them using the support vector machine (SVM). Thus, all BC datasets were diagnosed using AlexNet + SVM and GoogLeNet + SVM. The second proposed method diagnoses all BC datasets by ANN based on combining CNN features with handcrafted features extracted using the fuzzy color histogram (FCH), local binary pattern (LBP), and gray level co-occurrence matrix (GLCM), which collectively is called fusion features. Finally, the fusion features were fed into an artificial neural network (ANN) for classification. This method has proven its superior ability to diagnose histopathological images (HI) of BC accurately. The ANN algorithm based on fusion features achieved results of 100% for all metrics with the 400× dataset.

Electrified four-ball testing – A potential alternative for assessing lubricants (E-fluids) for electric vehicles

The increasing worldwide demand for hybrid and electric vehicle technology has brought new challenges for the global lubricant industry. The new lubricants for electric vehicles, also called E-fluids or EV-fluids, are expected to meet a new set of requirements including withstanding the much severe operating conditions of EV powertrains. High starting torques, high RPMs and uncontrollable shaft currents passing through the contact interfaces are some of the most challenging powertrain conditions that can impact the performance of these lubricants. Although there have been some papers already reporting on significant alteration of tribological properties of lubricants under electrification, so far there are no standard test protocols aimed at the fast and reliable screening of base oils, additives and formulated lubricants under such conditions. Thus, this research work focuses on exploring the popular four-ball ASTM-D4172 standard method to evaluate the tribological behavior of lubricants under electrified conditions. Specifically, a conventional four-ball tester was instrumented with a DC power source and a resistance data logger was used to explore the friction and wear performance of various lubricants (including a neat base oil, two automatic transmission fluids (ATF-3 and ATF-5) and a gear oil) with different dielectric strength under the conditions of ASTM-D4172 standard with and without DC currents (0, 1.5 and 3 A). The changes in average wear scar diameter, specific wear modes and mechanisms, friction coefficients, electrical contact resistance and temperature were analyzed and reported. Besides, the chemical changes in oils during the electrified tests were evaluated via IR spectroscopy. The main findings suggest that passing current through the four-ball contact interfaces significantly alters friction, wear and temperature in comparison to the conventional standard method without electrification. Thus, the proposed test method with electrification could be a potential new alternative for testing E-fluids under electrical environments.

Performance analysis of applying waste heat and moisture utilization in a highly efficient hybrid atmospheric water harvester

Atmospheric water harvesting (AWH) can supplement freshwater in regions far from natural water reserves, and hybridizing different AWH technologies is known to increase the water generation rate. This research proposes an improved hybrid technology where the waste heat and unrecovered water from the vapor compression cycle-based AWH are recycled into a salt solution circuit-based AWH. Doing so eliminates the significant energy input for the second AWH and greatly minimizes the specific energy consumption. A system is designed to achieve this concept, which is analyzed via a comprehensive simulation that couples the thermodynamic models of the vapor compression cycle, humid air, and custom-designed salt solution circuit. The influences of ambient relative humidity, mass flow rates of humid air and the salt solution, etc., are conducted to find the optimal working conditions. Results demonstrate that, under an ambient relative humidity and temperature of 50% and 30℃, respectively, the proposed method can reduce the specific energy consumption to 315 Wh/kg, which equates to a 34.4% energy-saving rate over the basic vapor compression cycle based AWH. This is achieved by lowering the airflow and salt solution flow rates to 0.1 kg/s and 0.03 kg/s, respectively, while using a 1000 W compressor.

Hybrid Technology Seawater Desalination Based on Reverse Osmosis and Membrane Distillation Methods

The article presents the results of a computational and analytical study of hybrid RO–MD (Reverse Osmosis–Membrane Distillation) technologies for desalination of the Caspian Sea, providing for the production of an additional amount of desalinated water by the MD method from RO concentrates heated to 50–80°C due to waste heat of fuel combustion products in steam boilers. Two options for solving the problem of the formation of CaCO3 and CaSO4 precipitates on membranes were studied: with preliminary nanofiltration (NF) or Na-cationation (Na) of sea water, as an alternative to the use of antiscalants (AS) and acid. The negative environmental effect of most plants (eutrophication of water bodies) and their low efficiency at high concentrations of desalinated water are taken into account. The Langelier index (СаСО3) and the degree of concentrate saturation (СаSO4) were used as criteria for precipitation of deposits on the membranes. The NF and RO processes were studied using the ROSA computer program, and the MD and Na processes were studied by computer simulation of the corresponding calculation models. It was found that at a 70% permeate yield at the NF and RO stages, the possibility of calcium precipitation on the RO and MD membranes is prevented, but their precipitation on the NF membranes is predicted, which makes the use of AS forced. At the same time, additional permeate production at the MD stage from RO concentrates reaches 40% of the amount of permeate from RO stadium, and the electricity consumption in general according to the scheme is 1.88 kWh/m3. Reducing the calcium hardness of sea water to 50 µg-eq/dm3 by the Na-cationization method makes it possible to refuse both the use of AS and acidification with sulfuric acid with additional production of MD permeate – 27% relative to RO permeate. Electricity consumption rises to 2.5 kWh/m3. To use the known advantages of NF without the use of AS, a hybrid Na–NF–RO–MD scheme is proposed. It has been established that at 80% yields of NF and RO permeates, to prevent the formation of CaSO4 precipitates at all stages of treatment, it is sufficient to reduce the hardness of sea water from 16 to 5.5 m-eq/dm3, and by acidifying the softened water to exclude the formation of CaCO3 precipitates.