LiBr Research Articles

Ab Initio Molecular Dynamics Simulations of the Influence of Lithium Bromide on the Structure of the Aqueous Solution-Air Interface.

We present the results of ab initio molecular dynamics simulations of the solution–air interface of aqueous lithium bromide (LiBr). We find that, in agreement with the experimental data and previous simulation results with empirical polarizable force field models, Br– anions prefer to accumulate just below the first molecular water layer near the interface, whereas Li+ cations remain deeply buried several molecular layers from the interface, even at very high concentration. The separation of ions has a profound effect on the average orientation of water molecules in the vicinity of the interface. We also find that the hydration number of Li+ cations in the center of the slab Nc,Li+–H2O ≈ 4.7 ± 0.3, regardless of the salt concentration. This estimate is consistent with the recent experimental neutron scattering data, confirming that results from nonpolarizable empirical models, which consistently predict tetrahedral coordination of Li+ to four solvent molecules, are incorrect. Consequently, disruption of the hydrogen bond network caused by Li+ may be overestimated in nonpolarizable empirical models. Overall, our results suggest that empirical models, in particular nonpolarizable models, may not capture all of the properties of the solution–air interface necessary to fully understand the interfacial chemistry.

Thermodynamic analysis of a biomass gasifier driven combined power and ejector - absorption refrigeration (CPER) system

This paper provides the thermodynamic study of an advanced power, cooling and refrigeration system which derives the required energy from biomass gasification and waste heat recovery operated ejector - absorption refrigeration system. The system deploys refrigerants such as R-141b and lithium bromide - water mixture as the working fluids which eventually generates the cooling and refrigeration simultaneously with stack gases. First and second law efficiencies are calculated to determine the effects of the crucial thermodynamic properties on turbine inlet temperature to heat recovery steam generator, turbine inlet pressure, evaporator temperature, change in biomass materials and then exergy destruction of each components of the system. It is observed that both first and second law efficiencies of the system decreases with increase in turbine inlet pressure but rises considerably with the increase in turbine inlet temperature. It is further observed that both the efficiencies rises with the employment of an ejector and absorption refrigeration by approximately 6.22% and 3.21% as compared to combined power cycle. Exergy analysis presented in this paper will gives a new dimension to the future researches in terms of reduced environmental impact and energy conservation.

Thermodynamic analysis of a biomass gasifier driven combined power and ejector - absorption refrigeration (CPER) system

This paper provides the thermodynamic study of an advanced power, cooling and refrigeration system which derives the required energy from biomass gasification and waste heat recovery operated ejector - absorption refrigeration system. The system deploys refrigerants such as R-141b and lithium bromide - water mixture as the working fluids which eventually generates the cooling and refrigeration simultaneously with stack gases. First and second law efficiencies are calculated to determine the effects of the crucial thermodynamic properties on turbine inlet temperature to heat recovery steam generator, turbine inlet pressure, evaporator temperature, change in biomass materials and then exergy destruction of each components of the system. It is observed that both first and second law efficiencies of the system decreases with increase in turbine inlet pressure but rises considerably with the increase in turbine inlet temperature. It is further observed that both the efficiencies rises with the employment of an ejector and absorption refrigeration by approximately 6.22% and 3.21% as compared to combined power cycle. Exergy analysis presented in this paper will gives a new dimension to the future researches in terms of reduced environmental impact and energy conservation.

Water vapor uptake into hygroscopic lithium bromide desiccant droplets: mechanisms of droplet growth and spreading.

The study of vapor absorption into liquid desiccant droplets is of general relevance to a better understanding and description of vapor absorption phenomena occurring at the macroscale as well as for practical optimization of dehumidification and refrigeration processes. Hence, in the present work, we provide the first systematic experimental study on the fundamentals of vapor absorption into liquid desiccant at the droplet scale, which initiates a novel avenue for the research of hygroscopic droplet growth. More specifically we address the behavior of lithium bromide-water droplets on hydrophobic PTFE and hydrophilic glass substrates under controlled ambient conditions. Driven by the vapor pressure difference between the ambient air and the droplet interface, desiccant droplets absorb water vapor and increase in volume. To provide further insights on the vapor absorption process, the evolution of the droplet profile is recorded using optical imaging and relevant profile characteristics are extracted. Results show that, even though the final expansion ratio of droplet volume is only a function of relative humidity, the dynamics of contact line and the absorption rate are found to differ greatly when comparing data with varying substrate wettability. Droplets on hydrophilic substrates show higher absorption kinetics and reach equilibrium with the ambient much faster than those on hydrophobic substrates. This is attributed to the absorption process being controlled by solute diffusion on the droplet side and to the shorter characteristic length for the solute diffusion on hydrophilic substrates. Moreover, the apparent droplet spreading process on hydrophilic substrates when compared to hydrophobic ones is explained based on a force balance analysis near the triple contact line, by the change of liquid-vapor surface tension due to the increase in water concentration, and assuming a development of a precursor film.

Analysis of Lithium Bromide-Water (LiBr- H2O) Vapour Absorption Refrigeration System Using First Law of Thermodynamics

In the ongoing years, the interest for refrigeration innovation is rising since waste warmth from warm frameworks, for example, control plants or sunlight based vitality can be exhausted for their task. A large portion of the energies are send by the businesses because of consumption of petroleum derivatives and expanding the fuel Price to use the most extreme accessible vitality from the waste warmth sources. Absorption cooling offers the likelihood of utilizing waste heat to give cooling. The goal of this paper is to show observational relations for finding the attributes and execution of a solitary stage Lithium bromide - water (LiBr-H2O) vapor absorption refrigeration system. The fundamental heat and mass exchange conditions and suitable conditions depicting the thermodynamic properties of the working fluid at all thermodynamic states are assessed. The first Law of Thermodynamics is connected to a single stage Lithium Bromide-Water Vapor Absorption Refrigeration framework, and the execution examination of every part is determined through numerical model on MATLAB 7.0.1. First law of thermodynamics is additionally used to ascertain to assessment of mass flow rate and heat rate in every part of the framework. Estimated the thermodynamic properties and Energy transfer rate in every part of Vapor absorption refrigeration system, with the assistance of empirical relation. Mass stream rate and heat flow rate in every segment of the framework are classified. The coefficient of performance of the system is deciding for different temperatures ranges. It very well may be seen that when the temperature of inlet water expands, the required circulation ratio diminishes, and the system COP esteem increments. In the event that the temperature is underneath 58°C, the system COP will be near zero, the system does not work by any means and from 58°C to 83°C, the COP will increment in a slower pace, after 83°C of generator temperature the COP increment quickly.

High-yield synthesis of glucooligosaccharides (GlOS) as potential prebiotics from glucosevianon-enzymatic glycosylation

Glucooligosaccharides with potential prebiotic functions were synthesized from glucose in high yield and selectivity in acidic lithium bromide trihydrate medium.

Experimental investigation of a plate heat exchanger model for lithium bromide absorption chillers: first results

In this paper the results of thermal-hydraulic tests of a sample of a perspective plate heat exchanger under the conditions of LBAHT is described. Working opportunity of the sample working under conditions of LBAHT has been confirmed by this research.

Design and analysis of a multigeneration system with concentrating photovoltaic thermal (CPV/T) and hydrogen storage

Concentrated photovoltaics (CPV) is an auspicious technology to overcome the high cost problem of highly efficient multi-junction solar cells. However, due to huge concentration of light energy, high heat flux dissipation from a confined space is a challenge. The proposed system here is first of its type to apply and thermodynamically analyze the Nucleate Pool Boiling Heat Transfer (NBHT) for thermal management of CPV. In order to increase overall efficiency of CPV system, a multigeneration system using concentrated photovoltaic thermal (CPV/T) and hydrogen storage is designed and thermodynamically analyzed to fulfill electricity, hot and cold water, heating ventilation and cooling (HVAC) requirement of a residential community with continuous operation. A part of the generated electricity from CPV is used to power the electrolyzer to produce hydrogen and oxygen. The produced gases are stored, and reused by proton exchange membrane fuel cell (PEMFC) to fulfill the system's electrical energy requirement during night time and unfavourable energy conditions in day time. The resultant thermal energy from CPV/T is used for the heating, hot water and cooling requirement of the buildings by employing lithium bromide absorption chiller (AbC). A humidity harvesting system is connected, at the outlet of the absorption chiller, to convert humid air into water and ventilation air requirement of the building. The designed system performs at 67.52% overall energy efficiency, 34.89% of overall exergy efficiency and up to 1862 times concentration ratio at designed steady-state conditions. The results show that with an increase in boiling temperature of NBHT from 353 K to 373 K, the maximum concentration ratio ability increases significantly from 1392 to 2400 times due to increase in critical heat flux, while the electrical efficiency of the CPV system decreases from 28.65% to 27.09% because of increase in cell temperature. To verify the performance of the designed system for different locations, operating conditions and capacities, the effects of Direct Normal Irradiance (IDNI), ambient temperature, relative humidity ratio and the installed capacity are also analyzed by the parametric studies.

Adsorption mechanisms of alcoholic additives in water at low pressure – An experimental study

Alcoholic additives are used to enhance the heat and mass transfer of the absorber, which has been widely recognized as the bounding device of an absorption chiller. Small quantities of additives in the aqueous lithium bromide solution reduce its surface tension, leading to a better wetting of the tube bundle of the absorber and triggering the Marangoni convection. Nevertheless, the enhancement mechanism relies on many parameters which have not been yet studied in details. In this work, the adsorption mechanisms of surfactants at the interface of water drops are experimentally investigated. 2-ethylhexanol, 1-octanol, 3,5,5-trimethyl-1-hexanol and 3-phenyl-1-propanol are chosen as additives and are added to water in different concentrations. The static and dynamic surface tension is measured according to the pendant drop method and the surface excess concentration is hereafter calculated with the Gibbs isotherm. Drops are generated in a saturated atmosphere without inert gases at low pressure, which represents the real working condition of an absorber. The results show that 2-ethylhexanol, 1-octanol and 3,5,5-trimethyl-1-hexanol lead to high surface tension reduction at high concentrations, and they are characterized by a fast diffusion and adsorption. Contrary, 3-phenyl-1-propanol presents a slow adsorption kinetic and is not effective in reducing the surface tension of water.

Performance Study of a Novel Integrated Solar Combined Cycle System

Based on a traditional integrated solar combined cycle system, a novel integrated solar combined cycle (ISCC) system is proposed, which preferentially integrates the solar energy driven lithium bromide absorption refrigeration system that is used to cool the gas turbine inlet air in this paper. Both the Aspen Plus and EBSILON softwares are used to build the models of the overall system. Both the thermodynamic performance and economic performance of the new system are compared with those of the traditional ISCC system without the inlet air cooling process. The new system can regulate the proportions of solar energy integrated in the refrigerator and the heat recovery steam generator (HRSG) based on the daily meteorological data, and the benefits of the solar energy integrated with the absorption refrigeration are greater than with the HRSG. The results of both the typical day performance and annual performance of different systems show that the new system has higher daily and annual system thermal efficiencies (52.90% and 57.00%, respectively), higher daily and annual solar photoelectric efficiencies (31.10% and 22.31%, respectively), and higher daily and annual solar photoelectric exergy efficiencies (33.30% and 23.87%, respectively) than the traditional ISCC system. The solar energy levelized cost of electricity of the new ISCC system is 0.181 $/kW·h, which is 0.061 $/kW·h lower than that of the traditional ISCC system.

The experimental study on the influence of crown ethers and glycols on the mutual solubility of lithium bromide in water

In this paper, the continuation of our work on searching for anti-crystallization additives to the aqueous solution of lithium bromide is presented. This type of research is important from the viewpoint of absorption refrigeration technology to improve the performance of the efficiency of refrigeration equipment. In this study, three crown ethers: 12-crown-4, 15-crown-5, and 18-crown-6 as well as the glycols: ethylene glycol, diethylene glycol, triethylene glycol and glycerol were investigated as anti-crystallization additives for {LiBr (1) + water (2)} system, conventionally used as a working pair in absorption refrigeration technology. For this purpose, the solubility of lithium bromide in water has been determined in the presence of the organic additive. The solubility measurements have been carried out using a dynamic method at a wide temperature and composition range for different (additive to LiBr) initial mass fraction from w20 = 0.1, 0.2 and 0.3. From experimental SLE data, the comparison range of the liquid state for tested systems at the absorber's working temperature was determined and compared to those from conventional (LiBr + water) system. Further measurements of vapor – liquid equilibria will be performed to select the best anti-crystallization additive.

Advanced Exergy Analysis of a Compression–Absorption Cascade Refrigeration System

This work presents a theoretical thermodynamic study of a compression–absorption cascade refrigeration system using R134a and a lithium bromide–water solution as working fluids. First and second law of thermodynamics analyses were carried out in order to develop an advanced exergetic analysis, by splitting the total irreversibility and that of every component. The potential for improvement of the system is quantified, in the illustrated base-case 55.4% of the irreversibility is of avoidable nature and it could be reduced. The evaporator is the component that shows a significant potential for improvement, followed by the cascade heat exchanger, the compressor, and finally, the generator. The results of the advanced exergetic analysis can be very useful for future design and experimentation of these kinds of systems.

Performance improvement of power plants using absorption cooling system

In the present paper, an integration of a (Lithium Bromide–Water) absorption inlet air cooling scheme to a cooled gas turbine-based combined cycle was analyzed. The waste heat energy of the exhaust gas prior to the exit of the waste heat recovery steam generator was chosen to power the cooling system. Nubaria Power Station, 120 km South East of Alexandria has been selected as a reference plant for the present study. It includes 3 generation modules, each including 2 * 250 MW gas turbine and 250 MW Steam turbine. A thermodynamic model of the overall integrated scheme of the cooling and power cycles is introduced. A parametric study of the effect of different operational conditions, namely; ambient temperature, relative humidity, compressor inlet air temperature, and part load on performance parameters was carried out. The model shows an increase of 11% in the produced electricity when the inlet air was cooled from 30 °C to 10 °C, Also, harvesting of condensed fresh water at a rate of 3.5 gm per kg of inlet air at ambient relative humidity of 60%. The model results have been verified by observing the real performance of the plant at various ambient conditions to ensure the accuracy of the model predictions.

Fabrication of porous silk fibroin/cellulose nanofibril sponges with hierarchical structure using a lithium bromide solvent system

Porous silk fibroin (SF) sponges have been widely used in biomaterials due to their excellent biocompatibility and tunable degradability. However, it remains a challenge to construct porous SF materials with 3D nanofibrous structure mimicking extracellular matrix. In this study, a novel strategy was developed to fabricate SF/cellulose sponges with micro-nano hierarchical structure through using a lithium bromide aqueous solution system. It was found that the cellulose can be partially dissolved by lithium bromide solution to form abundant cellulose nanofibrils (CNFs). Therefore, the porous SF/CNF sponge was directly prepared after dissolving SF/cellulose blend in lithium bromide solution. The structure and performance of sponges can be regulated by adjusting SF/cellulose ratio. Raising the cellulose ratio enhanced the compression strength and water swelling ratio of sponges, but restrained the 3D spatial distribution of CNFs in the pore space. As SF content increased to 50%, CNFs homogeneously dispersed and formed the porous sponges with micro-nano hierarchical structure. FTIR and XRD results showed cellulose II and silk II structure in composites, and suggested the presence of intermolecular interaction between SF and cellulose. The enzymatic degradation results showed that the degradation rate of sponges could be regulated by the SF component, which significantly promoted degradability. The results provide promising scaffold candidate with tunable nanostructure and degradability.

Kinetic Studies of Acid Hydrolysis of Food Waste-Derived Saccharides

Starch saccharified glucose from food waste can be an important precursor for renewable chemicals and fuels. Despite numerous studies on hydrolysis of biomass, detailed kinetic studies and associated models of hydrolysis are lacking. We investigated the kinetics of glycosidic bond scission of malto-oligosaccharides in lithium bromide acidified molten salt hydrate (AMSH) medium and estimated rate parameters from experimental data. Our data support the hypothesis that the terminal, nonreducing bonds hydrolyze faster than the interior and terminal-reducing C–O bonds. Next, we extended the model to simulate the hydrolysis of linear and cyclic saccharides of varying degree of polymerization and of potato starch. We characterize starch using X-ray diffraction (XRD) and light scattering methods. The model is in excellent agreement with the experimentally determined concentrations of glucose and other oligosaccharides. The chain length of saccharides is found to be directly related to their hydrolysis rate consta...

Multi-objective optimization of double effect series and parallel flow water–lithium chloride and water–lithium bromide absorption refrigeration systems

In this study, multi-objective optimization of the series and parallel flow type double effect absorption refrigeration systems is presented. Genetic algorithm is used to find the optimal solutions and the Pareto-optimal fronts. First, a thermodynamic model is developed to simulate the double effect series and parallel flow configurations with water–lithium chloride and water–lithium bromide solution pairs. Energy and exergy balances are applied to evaluate coefficient of performance, exergy efficiency and irreversible losses in the system components separately for the two working fluid pairs. Next, optimization is done considering coefficient of performance, exergy efficiency and the total system irreversibility rate as objective functions. The low and high pressure generator temperatures are taken as decision variables in the series configuration while for the parallel system; additionally the distribution ratio is also taken as a decision parameter. The optimization is done for four different cases of fixed evaporator, absorber and condenser temperatures. For each case, the optimal decision parameter values are determined for both the water–lithium chloride and water–lithium bromide operated double effect series and parallel configurations. The optimized coefficients of performance were found slightly lower for water–lithium chloride. Contrary to this, the optimal exergy efficiencies were more and the total system irreversibility were less for water–lithium chloride. Further, the optimal performances of the double effect water–lithium chloride systems were obtained comparatively at lower generator temperatures than those of the water–lithium bromide systems.

A modified procedure for the evaluation of the amylose and amylopectin content in potato starch

The article is devoted to the development of a technique for determining the content of amylose and amylopectin, effective for potato starch. Since potato starch is an important renewable raw material for a number of industries, it is important to have a throughput approach that allows potato starch samples to be tested quickly for the content of its constituent polysaccharides for potato breeding for starch properties and for starch industrial application. The developed technique includes elements of previously disjointed procedures for dissolution and spectrophotometric determination of amylose in starch, and combines the following advantages: 1) starch samples dissolve in an organic solvent (0.5 % solution of lithium bromide in dimethyl sulfoxide (DMS)); 2) measurement of light absorption is performed at two wavelengths, 550 and 510 nm, and 3) the technique is adapted for use with a plate spectrophotometer. This procedure allows starch polysaccharides to avoid to avoid hydrolysis during dissolution, allows the precise spectrophotometric determination of the concentration of amylose complex with iodine in solution, and opens the possibility of using this technique for throughput phenotyping. Applying a certain dissolution procedure, it is also possible to avoid the formation of gelled starch clots in solutions for spectrophotometry, which is important for the preparation of solutions containing amylose and amylopectin in the same proportions as in the original starch. The technique was tested on starch isolated from potato tubers varieties Lina, Velikan, Golubizna, Favorit of domestic selection. The technique developed can be used for phenotyping starch of an extended set of potato varieties (determining the content and composition of amylose in potato starch samples) to identify "trait-genotype” associations.

A detachable plate falling film generator and condenser coupling using lithium bromide and water as working fluids

A novel detachable plate falling film heat and mass exchanger (HMX) coupling using lithium bromide and water as working fluids is proposed, with both maintainability and compactness taken into account and a prototype built. The HMX coupling can be applied as either a generator and condenser coupling, or an absorber and evaporator coupling in an absorption heat pump using water as refrigerant. The prototype, working as generator and condenser coupling, was evaluated and analyzed experimentally. In a sensitivity study of the operating variables of generator, heat transfer coefficient of the generator varied between 0.345 kW/ (m2·K) and 0.660 kW/ (m2·K), while the mass transfer coefficient of the generator was between 2.7 × 10−5 m/s to 7.8 × 10−5 m/s. The heat transfer coefficient of the condenser varied from 0.627 kW/ (m2·K) to 0.731 kW/ (m2·K), and the minimum generation rate of the designed condenser to maximize its heat transfer capability is 3.85 g/s.

Harvesting Nannochloropsis sp. using PES/MWCNT/LiBr membrane with good antifouling properties

One of the greatest challenges to maintain sustainability in algae-based biorefinery is an effective harvesting process. Membrane filtration has become one of the methods for microalgae harvesting due to its versatility in separation. However, membrane fouling which arises from the interaction between algae cell and membrane surface significantly impedes the efficient application of the membrane technology. Thus, this paper reports on the feasibility of microalgae harvesting using good anti fouling PES membranes. The antifouling PES membranes were fabricated using multiwall carbon nanotubes (MWCNT) and lithium bromide (LiBr) as additives in dimethylacetamide (DMAC). Our results revealed that membrane fabricated with 1 wt% MWCNT, 5 wt% LiBr and 18 wt% PES via thermally induced phase separation (TIPS) process possessed an excellent filtration performance and anti-fouling effect. 28 g/l Nannochloropsis sp. have been fully retained using the fabricated membrane with average flux 28.9 L/m2h. Furthermore, the membrane demonstrated excellent anti-fouling effect owing to its higher membrane hydrophilicity indicated by the low contact angle value of 33.8°. Durability study performed exhibited 100% flux recovery rate after rinsing with tap water. The membrane demonstrated no fouling detrimental effects even after five cycles via consistent flux.

Electrical properties of lithium bromide poly ethylene oxide / poly vinyl pyrrolidone polymer blend elctrolyte

The development of Lithium batteries has gained more attention nowadays. polyethylene oxide (PEO)/Polyvinyl pyrrolidone (PVP) based Solid polymer electrolytes (SPEs) was prepared with lithium bromide by solution casting technique. From the X-ray diffraction studies, the amorphous nature of the polymer blend with the inclusion of LiBr had been studied. FT-IR study was used to find the presence of functional groups and the complex formation between the bonding of polymers. The maximum ionic conductivity was found to be 1.59 × 10−6 S/cm for PEO (30 wt %)/PVP (70 wt %)/Lithium bromide (4 wt %) at 303 K within the frequency range of 42 Hz - 1 MHz. The dielectric response of the SPE systems was studied at the temperature range of 303–363 K. An important factor of ion conduction is the relaxation behavior of polymer chains which was clarified by the dielectric properties of the SPE systems. Further, the capability of the polymer to dissolve salt was determined by the dielectric constant (ε). At lower frequencies, the higher dielectric permittivity was attained due to deposit of ionic charges. The ionic movement enhances the dielectric loss and dielectric permittivity. The conductivity relaxation process and the ion hopping mechanism have been explained by using the Electric modulus analysis.