Ammonia-water Solution Research Articles

Performance research of a solution cross-type absorption-resorption heat transformer using NH3/H2O work fluid

Absorption-resorption heat transformer (ARHT) can realize the efficient utilization of low-grade heat under lower operating pressure than traditional absorption heat transformer (AHT), but the application is limited by the low coefficient of performance (COP). In this paper, an ammonia-water solution cross-type absorption-resorption heat transformer is proposed to improve the performance. The rectifier can be eliminated because the component can be balanced with the adjustment of solution's mass flow rate between the absorber and resorber. A thermodynamic model is established to investigate the influences of different parameters on the coefficient of performance. The results reveal that: When the high/low pressure pair is 1.5/0.48 MPa and the temperatures of generator, absorber, resorber and desorber are 105 °C, 80 °C, 80 °C and 4 °C, the COP of the proposed system can reach 0.4049, which is 19 % higher than traditional ARHT, resulting in a corresponding gross temperature lift (GTL) is 25 °C. Besides, the proposed system has wider working temperature ranges than the traditional system. The advantages of the proposed system also include the lower optimal low-pressure values. Therefore, the ammonia-water solution cross-type absorption-resorption heat transformer is appropriate for working in larger pressure differences and makes waste heat recovery more economical and efficient.

Designing energy-efficient hardware and technological structure of absorption refrigeration units for ammonia production

The object of research is the equipment and technological design of absorption refrigeration units (ARUs) for the technological system of secondary condensation of large-scale ammonia production. Improving the energy efficiency of ARU is an urgent problem in the general process of reducing operating costs for natural gas in these industries as a whole. Based on the results of analytical studies, the feasibility of combining absorption-refrigeration and vapor-ejector cycles was substantiated, which ensures a decrease in the boiling temperature of a weak water-ammonia solution in the cube of the generator-rectifier and an increase in the condensation pressure in the ARU cycle. Under such circumstances, it becomes possible to increase the concentration of the refrigerant due to the rectification of steam with a part of the liquid refrigerant without using a pump with the removal of the dephlegmator from the ARU circuit. Experimental studies and material-thermal calculations of ARU cycles were carried out to determine the basis of comparison and the proposed version of the ARU scheme. It has been proven that the new technological design of ARU provides an increase in cooling capacity from 3.22 MW to 3.6 MW (by 12 %), the thermal coefficient from 0.527 to 0.551 (by 4.6 %), a decrease in the circulation ratio from 7.77 to 7.1 (by 8 %), and a decrease in the secondary condensation temperature by 2.5 ℃. It is shown that for the proposed version of the technological design of ARU, there is a change in specific costs – an increase in electricity by 1.48 kWh/t NH3 and a decrease in natural gas by 0.41 nm3/t NH3. Taking into account existing cost indicators for natural gas and electricity, the application of the proposed technology ensures a decrease in annual operating costs by UAH 7 million (USD 185,000), and therefore an increase in the economy of ammonia production as a whole

Evaluating the Effectiveness of Proportional Nodes Method in Curve Fitting for Surfaces: Application to Data of Dynamic Viscosity of Ammonia-Water Solution

This study used the proportional nodes method, a novel curve fitting approach to correlate data for dynamic viscosity of ammonia-water solution. The approach integrates polynomial equations, generated at various temperatures, with those calculated at selected mole fraction nodes. These nodes are scaling factors that account for variations in dynamic viscosity at different temperatures at selected mole fractions. The accuracy of the polynomial equations ensures a high degree of fitting accuracy. The proportional nodes, computed systematically, were integrated into a robust and highly accurate polynomial model to generate correlations that fit the data for the surface. This model exhibited minimal average percentage differences between predicted and actual viscosity values (±0.2614293 for temperature range, 273.15K to 303.15K and ±1.11 for temperature range, 303.15K to 423.15 K), indicating a high level of predictive accuracy. The proportional nodes method offers a significant contribution to both academic research and industry. It provides a more precise and adaptive model for predicting the dynamic viscosity of ammonia-water solution, which is critical for optimizing and designing various industrial applications, including refrigeration systems.

Alloy Design for AM: A Ferritic Alloy for Applications in Corrosive Alkaline Environment

Alloy design allows to define specific compositions of materials having certain technological requirements as boundary conditions. Moreover increasing interest raised in the last decades on materials for Additive Manufacturing (AM). These new technologies consider a new approach, i.e. bottom up, for component manufacturing and suitable materials in different forms, generally liquid or solid (powders, filaments). One of the most interesting advantages of AM is the potentiality of realizing components with complex geometries and in a single or in few pieces to be assembled. For this reason, in this work a ferritic allow has been designed with the scope of realizing heat exchangers for highly corrosive alkaline environments. Water-ammonia solution are in-fact used in absorption machines for refrigeration and several heat exchangers are required for its thermodynamic cycle. After defining a specific composition, also on the base of thermodynamic simulations, the alloy has been produced by Vacuum Induction Melting (VIM). After suitable thermal treatments microstructural, mechanical and thermal characterizations have been carried out.

Assessment of gasoline engine performance and emissions powered by different gasoline-water ammonia blends: A Review

As a result of a large number of diseases due to environmental pollution resulting from emissions and fast energy depletion. Many researchers resorted methods to produce a mixture that can be used as fuel and fight these issues. In this work, a mini review was concluded through previous studies to highlight and investigate the effect of using water ammonia solution on the characteristics of IC engines with special focus on gasoline engines. The main findings showed decreased engine performance because ammonia has a lower calorific value and energy density. also, most of the previous contributions highlighted a significant reduction in CO2 and CO emissions for all loads. Using ammonia solution increased NOx emissions slightly.

Analysis of the possibilities of increasing the energy efficiency of absorption refrigeration appliances through the use of refrigerating accumulators

One of the most important tasks of modern society is the solution of environmental and energy problems in power engineering and, in particular, refrigeration technology. At the same time, in the field of artificial cooling systems, it is necessary to solve the problems of reducing the impact on both the ozone layer and the greenhouse effect. An effective approach here can be absorption refrigeration systems with a natural working fluid (water-ammonia solution), which does not adversely affect the environment. For the effective use of absorption refrigeration systems, it is necessary to solve the problems of increasing their energy efficiency, in particular, through the use of cold accumulators. Thus, the object of research is absorption-type cooling systems with cold accumulators.
 The paper analyzes cold accumulators with different physical nature. It is shown that melting substances can be the most effective for solving problems of low-temperature cooling. An analysis of the thermal scheme of an absorption freezer of the «chest» type, which is the most problematic in terms of providing cooling modes at a level of (–18)–(–24) °С, was carried out. Optimization thermal calculations for typical absorption freezers up to 200 dm3 have been performed. It is shown that when the chamber is initially loaded with a product at an ambient temperature, the cooling capacity of the installed absorption refrigeration units is not enough – no more than 50 % of the required one. For an absorption freezer of the «chest» type, the most suitable cold-storage materials are a eutectic aqueous solution of sodium chloride or propylene glycol, since these solutions have the desired melting point of the order of –18 °C and a fairly high melting heat. The result of optimizing the weight and size characteristics of the internal volume of the absorption freezer is the following recommendations:
 – the optimal size of wire baskets for placing products is 315´370´240 mm;
 – the gaps between the basket and the cabinet wall, as well as between the baskets themselves, should be 10 mm to ensure normal convection conditions;
 – it is not advisable to place fans inside the volume of the freezer at this stage, since the freezing time is reduced by a maximum of 30 %, but this results in additional heat generation, energy consumption and increases the shrinkage of the products stored in the chamber.

Assessment of diesel engine thermo-characteristics working with hybrid fuel blends

The objective of this study is to examine the impact of multifuel blends on combustion parameters of single-cylinder four-stroke direct injection diesel engines. Engine characteristics (performance, combustion, and emissions) are scanned under the following scenario: initially powered by regular diesel (DF), then 20% biodiesel derived from spirulina green algae. Afterward, 40% water ammonia solution (25% NH3) is used, followed by a hybrid blend (40% DF + 20% biodiesel + 40% NH4OH). Simulations are performed using Diesel-RK software. In contrast to diesel and biodiesel, aqueous ammonia solution has a longer delay period due to lower cetane number. In comparison with diesel, the Sauter mean diameter (SMD) is increased by 1.6%, 3.8% for biodiesel and NH4OH, while it is decreased by 13% for hybrid fuel. Peak values of pressure and temperature are reduced. All fuel blends under consideration had significant reductions in nitrogen oxides (NOx) and Bosch smoke number (BSN). Hybrid fuel reduced NOx emissions by 37% and BSN by 53.5% compared to DF. Compared to DF, there was a slight increase in brake-specific fuel consumption (BSFC) coupled with a decrease in thermal brake efficiency (BTE). The optimal fuel compromise for dual-fuel diesel engines is the usage of biodiesel and aqueous ammonia together (hybrid mode). There is an excellent convergence between these outcomes and those of other scientists.

Energy, exergy, economic, and exergoeconomic analyses and optimization of a solar Kalina cycle using particle swarm optimization algorithm

In the present research, a Kalina cycle has been analyzed from the energy, exergy, economic and exergoeconomic points of view. In this cycle, the water-ammonia solution is used as the working fluid. Firstly, the mass balance, energy, and exergy equations are solved, then the initial cost and exergy destruction cost have been calculated using the cost balance equations in different components. Finally, the optimization of solar Kalina's performance in terms of target functions, i.e., total cost rate and exergy efficiency, has been performed. To this end, a relationship between design parameters and target functions is derived using the neural network algorithm; then, the multiobjective optimization of the cycle is performed using the particle swarm optimization (PSO) algorithm. The results show that total work, net irreversibility, and total exergy efficiency in the base case are 296.2kW, 3671kW, and 0.0738, respectively. The exergoeconomic analysis indicates that the total cost rate was 366$h, and it was found that the solar collector and Kalina evaporator have respectively the maximum cost rate. The parametric analysis has been performed in terms of energy, exergy, and exergoeconomic to examine the effect of turbine's inlet temperature and pressure, and ammonia content on the cycle performance. The optimization results indicate that exergy efficiency and total cost rate are 0.08824, and 318.58$h, respectively. This represents an 19.5% increase in the exergy and a 12.95% reduction in cost rate compared to the base case.

Performance analysis of a geothermal heat-powered resorption cooling system: a case study for cold storage of apple fruit

Abstract Renewable energy use in agricultural applications is essential for sustainable production. Resorption cooling systems can be operated for agricultural cooling applications by using thermal energy derived from geothermal springs with sufficient temperature. Since the resorption cycle uses ammonia-water solution, cold storage and industrial cooling processes below 0°C can be actualized efficiently. In this article, a geothermal powered resorption system for cold storage of apple fruit is investigated. Technical features and cooling performance of the resorption system are analysed and compared to the other conventional cooling systems. Results showed that, geothermal powered resorption cooling systems can annually cover the cooling load of the cold storage application with adequate cooling temperature and capacity. Moreover, the use of the geothermal powered resorption system enables to set up safer and more economic cooling applications with the similar cooling performance compared with the alternative sorption cooling systems, and provides substantial economic benefits by reducing the cooling costs in agricultural production with lower operational costs.

Establishment of LC-MS/MS Method for Determination of GMDTC in Rat Plasma and Its Application in Preclinical Pharmacokinetics.

Sodium (S)-2-(dithiocarboxylato((2S,3R,4R,5R)-2,3,4,5,6-pentahydroxyhexyl)amino)-4(methylthio)butanoate (GMDTC) is the first compound to use cadmium repellent as an indication. In this paper, we established and validated a bioanalytical method for the determination of GMDTC in rat plasma, and used it to determine the drug concentrations in the plasma of rats after intravenous dosing in different genders and dosages. After pretreating the plasma samples with an acetonitrile-water-ammonia solution (70:30:1.25, v/v/v), liquid chromatographic separations were efficiently achieved with a XBridge C18 column using a 5 min gradient system of aqueous ammonium bicarbonate and 95% acetonitrile-water solution (95:5, v/v) as the eluent. The GMDTC and metolazone (internal standard, IS) detection were carried out using high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS), monitored at m/z 390.06-324.1 (for the GMDTC, tR: 2.03 min) and m/z 366.0-259.2 (for IS, tR: 3.88 min). The GMDTC was stable under various testing conditions, and this analytical method conforms to the verification standard of biological analysis methods. The half-life (t1/2) was determined to be 0.54-0.65 h for the intravenous, mean distribution volume and clearances were 1.08-2.08 L/kg and 1-3 L/h/kg, respectively. The AUC0-t and AUC0-∞ found after increasing the dosage exhibited a linear relationship with the administered dose. There were no statistically significant differences in the values obtained for the different genders at dosages of 50, 100 and 250 mg/kg, respectively (p > 0.05). This is the first report of a bioanalytical method to quantify GMDTC in rat plasma using LC-MS/MS, which provides useful information for the study of its pharmacological effects and clinical applications.

Development and validation of two bioanalysis methods for the determination of etimicin in human serum and urine by liquid chromatography-tandem mass spectrometry: Applications to a human pharmacokinetic and breakpoint study.

Etimicin is a fourth-generation aminoglycoside antibiotic. It has potent activity and low toxicity when employed for the treatment of Gram-negative and Gram-positive bacterial infections. The pharmacokinetics of etimicin in humans have not been elucidated completely. Two liquid chromatography-tandem mass spectrometry (LC-MS/MS) bioanalytical methods, without the use of any ion-pairing reagents, were developed and validated for the quantification of etimicin in human samples of serum and urine. Using a deuterated reagent as the internal standard, analytes in serum and urine samples were extracted by protein precipitation and dilution before LC-MS/MS analysis, respectively. For the two methods, chromatographic separations were undertaken under isocratic elution of water-ammonia solution-acetic acid (96:3.6:0.2, v/v/v) and methanol at 50%:50% and a flow rate of 0.35ml/min within 5min. A Waters XTerra MS C18 column (2.1 × 150mm, 3.5μm) and a column temperature of 40°C were chosen. A Sciex Qtrap 5500 mass spectrometer equipped with an electrospray ion source was used in both methods under multiple-reaction monitoring in positive-ion mode. The two methods showed good linearity, accuracy, and precision with high recovery and a minimal matrix effect in the range of 50.0-20000ng/ml for serum samples and 50.0-10000ng/ml for urine samples, respectively. Carry-over effects were not observed. Etimicin remained stable in human samples of serum or urine under the storage, preparation, and analytical conditions of the two methods. These two simple and reliable methods were applied successfully to a dose-escalation, phase I clinical trial of etimicin in Chinese healthy volunteers after intravenous administration of single and multiple doses. Based on these two methods we ascertained, for the first time, the comprehensive pharmacokinetics of etimicin in humans, which will be used for the exploration of the breakpoint research further.

Review of Improving the NOx Conversion Efficiency in Various Diesel Engines fitted with SCR System Technology

The diesel engine is utilized in most commercial vehicles to carry items from various firms; nevertheless, diesel engines emit massive amounts of nitrogen oxides (NOx) which are harmful to human health. A typical approach for reducing NOx emissions from diesel engines is the selective catalytic reduction (SCR) system; however, several reasons make reducing NOx emissions a challenge: urea particles frequently become solid in the injector and difficult to disseminate across the system; the injector frequently struggles to spray the smaller particles of urea; the larger urea particles from the injector readily cling to the system; it is also difficult to evaporate urea droplets because of the exhaust and wall temperatures (Tw), resulting in an increase in solid deposits in the system, uncontrolled ammonia water solution injection, and NOx emissions problems. The light-duty diesel engine (LDD), medium-duty diesel engine (MDD), heavy-duty diesel engine (HDD), and marine diesel engine use different treatments to optimize NOx conversion efficiency in the SCR system. This review analyzes several studies in the literature which aim to increase NOx conversion in different diesel engine types. The approach and methods demonstrated in this study provide a suitable starting point for future research into reducing NOx emissions from diesel engines, particularly for engines with comparable specifications.

Nanocrystalline copper iodide enabling high-efficiency organic LEDs

High-efficiency organic light-emitting diodes (LEDs) can be achieved by employing efficiency-effective materials coupling with suitable device architectures. Among them, there have been numerous hole-injection and -transport materials reported, but having issues of high-cost, solution-process feasibility, and toxic solvent involvement. Here, we demonstrated a low-cost solution-processable nanocrystalline copper iodide (CuI) as a hole-injection and -transport material for the fabrication of high-efficiency organic LEDs. The CuI dispersion can be prepared by using a non-toxic ammonia-water solution with processing being carried out at a relatively low temperature of 110 o C. The annealed CuI film exhibited more superior optical properties, a better hole injection capability, and a better crystalline nature as comparing with the unannealed one or the typical hole-injection counterpart. The annealing resulted nanocrystalline CuI had enabled a green device with a maximum external quantum efficiency (EQE max ) of 17%, a maximum power efficacy (PE max ) of 64 lm W −1 and a maximum current efficacy (CE max ) of 62 cd A −1 , an increment of 54, 33 and 15%, respectively, as comparing with the unannealed counterpart. The respective increments are 35, 41 and 38% as comparing with the typical hole-injection material. Additionally, a blue hazard-free candlelight organic LED has also been fabricated with an EQE max of 15%, PE max of 43 lm W −1 and CE max of 41 cd A −1 . Electrical simulation was also performed to get recombination rate and electric field distribution in active layer. CuI based OLED exhibited higher recombination rate and lower electric filed distribution as comparing with PEDOT:PSS based OLED. The superior performance may be attributed to the enhanced recombination due to efficient injection, transport of holes, and a potential inner light scattering medium aiding light extraction due to its nanocrystalline nature. Our results show that the nanocrystalline CuI can be an inexpensive substitute for the conventionally used hole-injection materials to achieve high-efficiency lighting sources. • Nanocrystalline CuI as an effective Hole-injection/transport layer for organic LEDs. • CuI dispersion is prepared in a non-toxic ammonia-water solution. • Electro-simulation study comparison of CuI and PEDOT:PSS. • Superior device performance in comparison with PEDOT: PSS and amorphous counterpart.

Numerical Simulation of Ammonia-Water Solution Based Heat Absorber

This article provides an insight into the numerical simulation of an ammonia-water solution-based plate heat absorber, which is a crucial part of an absorption chiller. These chillers could be used as part of a stratified chilled-water storage tank configuration for coupling to a small modular reactor. The common approach utilized in the process of designing the chiller is to call the absorber a "black box" without considering the processes inside. It follows that the resulting design must be highly oversized to ensure reliable operation of the system. This article focuses on the obstacles that needs to be overcome in order to simulate the processes inside the absorber, such as stream breakup into separate droplets or absorption of ammonia. Unfortunately, we do not have any experimental data we could use to validate our simulations and thus this article should be looked at as a "proof of concept" and a possible guideline for simulations of similar phenomenon.

Improving a method for eliminating the spill of hazardous substances by using "Universal Absorbent Cloth"

In order to increase efficiency and implement the principles of resource saving during the elimination of emergency spills of dangerous goods when transporting them by rail, proposals have been offered to improve the method of localization and elimination of emissions of hazardous substances using the "Universal Absorbent Cloth" ("UAC") The specificity of localization of the emergency emission site and the principles of elimination based on sorption technologies using "UAC" are described. To manufacture "UAC", special equipment (carbonizer) was designed, which provides effective carbonization of raw materials from plant waste at sufficiently low temperatures ≤500 °C. Using a carbonizer, a universal sorbent was obtained, which is subsequently used for the manufacture of "UAC". The total carbonization time of plant waste samples did not exceed 60 minutes. The universal absorbent obtained during the carbonization process was placed in a fabric matrix to produce "UAC" absorbent cloth. Standardized procedures for conducting experiments are described. Studies of the adsorption characteristics of the proposed "UAC" involving various model solutions (Gasoline A-95, 25 % solution of ammonia water, and 15 % solution of hydrogen peroxide) confirm its versatility and efficiency; the degree of purification reaches 92 %. It is proposed to use certain types of railroad cars to transport "UAC" as part of a freight train, which is supported by the corresponding dynamic indicators. Recommendations for the regeneration or disposal of spent "UAC" cloth are provided. The proposals for improving the method of emergency emission elimination using the "Universal Absorbent Cloth" ("UAC") make it possible to minimize the negative consequences of emergency spills of liquid cargoes of different hazard classes and reduce the time spent on elimination operations. These advantages ensure the competitiveness and profitability of the proposed technology

HEAT AND MASS TRANSFER CONSIDERATIONS IN THE DESIGN OF A COILED ABSORBER FOR AMMONIA-WATER REFRIGERATION SYSTEM

The performance of the absorber significantly affect the overall efficiency of any absorption refrigeration system. One of the major reasons for the poor design of the absorber for ammonia-water refrigeration systems is the neglect of mass transfer resistances in the vapour or liquid phase in favour of only heat transfer considerations. Heat removal is critical to the absorption process, however, the ammonia gas is constantly absorbed by the liquid ammonia-water solution. This means that two-phase mass and heat transfer operations take place during the absorption process. Therefore, this implies that, for any proper absorber design, both heat and mass transfer considerations are paramount. Accurate absorber design is further predicated on accurate properties correlations. The correlations required for the absorber design include liquid and vapour enthalpies, saturated vapour pressure, specific heat capacity of water and ammonia vapour, liquid solution dynamic viscosity, liquid solution density, surface tension, liquid solution thermal conductivity, liquid-liquid diffusivity and vapour-liquid diffusivity. Procedures for calculating these parameters have been presented in this paper and their accuracy with previous studies compared. Results showed relatively low percentage deviations and so can be applied for the design and simulation of the absorber. Designs of the absorber for various cooling capacities have been carried in this paper. The variation of ammonia vapour temperatures, liquid ammonia-water solution temperatures, cooling water temperatures, and flow rates of ammonia-water solution and ammonia vapour across the absorber is investigated for the four cooling capacities. For refrigeration systems with cooling capacities of 1 kW, 2 kW, 3 kW and 4 kW, the calculated lengths for a water-cooled coiled absorber are 4.484 m, 8.1467 m, 12.50459 m and 14.78329 m respectively. The calculated overall heat transfer coefficients for the absorption process for the four cooling capacities (1 kW, 2 kW, 3 kW and 4 kW) were 0.4427, 0.4376, 0.4208 and 0.4309 kWm-2K-1 while the mass transfer coefficients were 3.721 x10-9, 4.206 x10-9, 4.556 x10-9and 4.856 x10-9 m2s-1 respectively. Concurrent flow is considered in this study, but the procedure can also be applied to countercurrent flow. KEYWORDS: Absorption Refrigeration, Ammonia Water Heat and Mass Transfer, Design

Performance of a Hybrid TEG/Single Stage Ammonia-Water Absorption Refrigeration Cycle with a Combined Effect of Rectifier and Condensate Precooler

In this article, a single stage ammonia-water absorption refrigeration cycle integrated with thermoelectric power generators driven by evacuated tube solar collectors is presented and investigated. The working fluid is ammonia-water solution, and the hybrid system was modeled, and analyzed using EES software. The system coefficient of performance (COP) was found to increase with increasing the generator temperature. From the results obtained, when the cycle operated with 0.99 ammonia mass fraction, it was found that the best location of the thermoelectric generators is at the rectifier between the generator and the condenser where the value of COP exceeds 0.82 at temperature difference across the TEG of 60℃. The other locations, between condenser-evaporator and evaporator-absorber, show similar performance.

Formulation of Correlations for Calculating Densities and Thermal Conductivities of an Ammonia-Water Solution

Formulation of Correlations for Calculating Densities and Thermal Conductivities of an Ammonia-Water Solution

Correlations for Liquid and Vapour Dynamic Viscosities for Ammonia-Water Solution

Correlations for Liquid and Vapour Dynamic Viscosities for Ammonia-Water Solution

Experimental Investigation of the Performance and Exhaust Emissions of a Spark-Ignition Engine Operating with Different Proportional Blends of Gasoline and Water Ammonia Solution

This paper aims to investigate the impact of water ammonia solution (WAS)-gasoline fuel (GF) blends on SI engine exhaust emission and engine performance characteristics and compare the obtained results with those using base gasoline. This investigation used a single-cylinder, four-stroke, air-cooled, and SI engine coupled with an AC generator to achieve this experimental work. Water ammonia solution fuel was blended with neat gasoline in volume rates of 5, 10,15,20, and 25%. The experimental investigation was conducted at an off-road engine under a constant engine speed of 3000 rpm and different load conditions. The results show that the use of ammonia solution as an addition to gasoline fuel increase the overall thermal efficiency, and G75Was25 blend obtained the maximum increase ratio of overall efficiency by 38.96% at maximum load condition in comparison to neat gasoline and reduce the specific fuel consumption compared with that of gasoline fuel. This alteration results in an elevation in CO, HC, and NOx emissions.