Decrease In Specific Energy Consumption Research Articles

Performances of air gap and water gap MD desalination modules

Abstract Membrane distillation (MD) is a promising thermally-driven membrane separation technology for water desalination. In MD, water vapor is being separated from the hot feed water solution using a micro-porous hydrophobic membrane, due to the difference in vapor pressures across the membrane. In the present work, experiments are conducted to compare the performance of water gap membrane distillation (WGMD) and air gap membrane distillation (AGMD) modules under the main operating and design conditions including the feed and coolant temperatures, membrane material and pore sizes, and the gap width. Results showed that the WGMD module produced higher fluxes as compared to the AGMD module, for all test conditions. The feed temperature is the dominant factor affecting the system flux. The permeate flux increases with reducing the gap width for both water and air gap modules. However, WGMD module was found to be less sensitive to the change in the gap width compared to the AGMD module. The PTFE membrane produced higher permeate flux as compared to the PVDF membrane. Bigger mean pore diameter enhanced the permeate flux, however, this enhancement is marginal at high feed temperatures. With increasing the feed temperature, the GOR values increase and the specific energy consumption decreases.

Multi-stage continuous and intermittent microwave drying of quince fruit coupled with osmotic dehydration and low temperature hot air drying

Abstract In recent years, using intermittent microwave (IM) to dry foodstuffs has been taken into consideration as one of the new drying methods in food industry. The aim of this research was to dry cubic pieces of pre-treated “quince” fruit by sucrose osmotic solution using IM – hot air (HA) drying at a low temperature (40 °C) in order to investigate the effects of this process on improving the dried product quality. The variables of the process included sucrose osmotic solution in 5 concentration levels of 0 (control), 10, 30, 50, and 70% (w/w) and microwave at 4 powers of 0 (control), 360, 600, and 900 W, with 4 pulse ratios of 1, 2, 3, and 4. Findings indicated that compared to control samples, the samples pre-treated by osmotic solution had lower effective moisture diffusion coefficient (Deff). However, Deff increased through increase in power and pulse ratio of the microwave. Increasing the concentration of the osmotic solution, power, and pulse ratio led to significant decreases in shrinkage. Due to high shrinkage, the quince samples dried by continuous microwave – HA method showed higher bulk density in comparison to the samples dried by IM – HA. In addition, samples dried by IM with low power showed the highest rehydration followed by those dried by IM with high power; however, the control samples dried merely by HA had the lowest rehydration. Moreover, a significant decrease in specific energy consumption was noticed through increasing the microwave power. Drying by IM – HA at the power of 900 W and the pulse ratio of 4 had the lowest specific energy consumption, while drying with only HA had the highest specific energy consumption.

A Combined Modeling and Experimental Study Assessing the Impact of Fluid Pulsation on Charge and Energy Efficiency in Capacitive Deionization

Cell-cycling performance in capacitive deionization (CDI) can suffer from various charge-efficiency loss mechanisms. In conventional CDI, we show that salt residue within electrodes introduces a temporal lag between charge and desalination stages of a CDI cycle. Without accounting for this effect in the collection of effluent, significant performance degradation occurs as current density increases. To overcome this we use pulse-flow operation to control fresh- and brine-water concentrations. The charge and energy efficiency performance between the two flow-modes is compared using a porous electrode model that is calibrated and validated with experimental data. To quantify specific contributions to charge efficiency losses, the model captures local salt variations resulting from a combination of electrosorption, leakage current, and immobile surface charge. Compared to traditional continuous-flow operation, simulation results show that charge efficiency increases up to 23% in the pulse-flow operation at a current density up to 20 A/m2, which leads to a 73% decrease of specific energy consumption (SEC). In addition, the SEC predicted by the pulse-flow operation model closely aligns with the predictions of the continuous-flow model after accounting for the temporal lag in effluent salinity. Both simulations and experimental results suggest that pulse-flow operation closely approximates the performance in continuous-flow operation.

Simulation Based Studies of Energy Saving Measures in the Aluminum Tool and Die Casting Industry

This study, which focuses on analyzing aluminum melting and die casting procedures is part of the Smart Melting project in the research network Green Factory Bavaria (GFB). The aim of the present research project is to investigate these procedures and to suggest measures to increase the overall energy efficiency. The analysis starts with the capture of the operating structure, the relations between supply and consumption of liquid aluminum and an evaluation of aluminum furnaces themselves. The study concentrates on shaft furnaces whose specific energy consumption is 25 % higher than stated by the manufacturers. At the same time the melting capacity of the furnaces ranges at the lower end according to the manufacturer's data. The reason for this deviation is a discontinuous operation mode due to demand fluctuations. Consequently the flue gas has still a high temperature which means a high waste of energy. Based on these facts the furnace charge and operation mode have to be optimized and the high temperature flue gas can be used to preheat the pig aluminum.A numerical model of aluminum furnaces is applied to investigate this optimization potential. This model can simulate either a single aluminum furnace (case 1) or a furnace integrated in the entire manufacturing plant (case 2). The advantage of case 1 is the furnace's operation on its most efficient point because there is no influence of the die casting process. In case 1 an improvement of the furnace charge leads to a higher capacity utilization and therefore to a reduction of 30 % specific energy consumption and a 50 % increase of melting capacity. Whereas in case 2 the simulation of the entire manufacturing plant results in a rise of 25 % melting capacity and a 16 % decrease of specific energy consumption. The simulation proved increasing energy efficiency due to preheating the pig aluminum in both cases.

Statistical Entropy Analysis and Experimental Study of LNG Plant with Precooling at –70°C

Statistical entropy analysis method is used to study an LNG plant operating on high-pressure cycle with precooling at –70°C. The degree of thermodynamic perfection and the plant-units-wise energy consumption distribution are determined by calculation and confirmed by experiment. It is shown that the plant can be perfected further by introducing a cascade precooling cycle into the plant circuit, whereupon the degree of thermodynamic perfection increases by 4.7% and the specific energy consumption decreases by 5%.

Experimental Investigations of Performance and Emissions Characteristics of Kusum (Schleichera Oleosa) Biodiesel in a Multi-Cylinder Transportation Diesel Engine

In the present work, an underutilized and promising feedstock, Kusum seed oil (KSO) is converted into biodiesel through transesterification process. The physico-chemical properties of Kusum biodiesel (Kusum oilmethyl ester; KOME), measured via standard methods, were well within the ASTM D6751/EN14214 standard limits. After that, experiments were conducted using various blends (B5, B10, B15, and B20) of methyl ester of KSO with diesel in a multi cylinder diesel engine at varying engine speeds, ranging from 1000 to 4000 rpm under full load conditions. Engine performance (brake power, brake specific fuel consumption, brake specific energy consumption and brake thermal efficiency) and emissions (CO, HC, NOx and smoke opacity) were measured to analyse the behavior of the diesel engine running on biodiesel. The test results showed that with the increase of biodiesel in the blends CO, HC and smoke opacity reduces significantly while fuel consumption and NOx emission of biodiesel increases slightly compared with diesel. Brake specific energy consumption decreases and thermal efficiency of engine slightly increases when operating on 10 % biodiesel than that operating on diesel. It may be concluded from the experimental investigations that Kusum biodiesel is a potential alternative to diesel fuel.

Performance Evaluation and Exhaust Emission of a Diesel Engine Fueled with CNSL Biodiesel

In this article, performance tests were carried out on a diesel engine with neat diesel fuel and biodiesel mixture. Biodiesel (cashew nut shell liquid) was made by pyrolysis process. Fuel blends were tested in a single cylinder, direct injection, water cooled diesel engine. The effects of Blend 10, Blend 20, Blend 30, and number-2 diesel on the engine power, torque, specific energy consumption, and exhaust gases temperature were ascertained by performance tests. The influence of blends on carbon monoxide (CO), nitrogen oxide (NO), carbon dioxide (CO2), hydrocarbon emission, and smoke opacity were investigated. The experimental results showed that the use of biodiesel improved the performance parameters and decreased the CO emission to 37% as compared to diesel fuel. Specific energy consumption decreases (35–45% approximately) and CO2 increasing by 36% are an indication of better combustion. Also, 20% by volume contents of cashew nut shell liquid oil in the blends can partially be substituted for the diesel fuel without any modifications in diesel engines.

Industrial versus Laboratory Clinker Processing Using Grinding Aids (Scale Effect)

The evaluation of grinding aid (GA) effect on clinker processing in laboratory grinding mills is relatively simple. Yet, the results obtained cannot be directly transposed to industrial mills, given the fundamentally different operational modes and grinding parameters. This paper seeks to evaluate the scale effect by comparing the results obtained from a closed-circuit tube mill operating at 90 ton/hr to those determined using a 50-liter laboratory mill. Tests results have shown that the decrease in specific energy consumption (Ec) due to glycol or amine-based GA can be evaluated under laboratory conditions. However, such tests underestimate the actual performance that could be achieved in real-scale mills; the Ec reduction due to GA is around twofold higher when grinding is performed in real-scale mill. Compared to industrial tests, the cement particle size distribution curves widened and shifted towards higher diameters when grinding was performed under laboratory conditions, particularly with GA additions. This led to remarkable changes in water demand, setting time, and 1- and 28-day compressive strengths.

Electromagnetism and the Arc Efficiency of Electric Arc Steel Melting Furnaces

Results of analytically studied effect of electromagnetic blowing and the slag height on the arc efficiency are stated. An arc is blown from under an electrode toward the furnace walls under an electromagnetic force, arc radiation on the wall and roof increase and effective output, absorbed by the metal decreases. EAF (electric arc steel melting furnace) with independently powered arcs, eliminating its electromagnetic blowing is proposed. When arcs are powered independently, its efficiency increases significantly, and specific energy consumption decreases.

Study on the recovery of ionic liquids from dilute effluent by electrodialysis method and the fouling of cation-exchange membrane

With the wide application of ionic liquids (ILs) in various fields, developing efficient techniques to recover ILs from effluent is an urgent demand for the cost reduction and the environmental protection. In this study, an electrodialysis (ED) method was used to recover 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) IL from aqueous solution as model effluent. The influences of initial IL concentration and applied voltage on the current efficiency, removal ratio, desalination ratio, membrane flux and specific energy consumption during the ED process were investigated. It was found that the removal ratio and desalination ratio increases with the increasing of initial IL concentration and applied voltage. The current efficiency decreases with the increasing of initial IL concentration and the current efficiency reached the maximum value of 94.3% at 25 V. Besides, as the applied voltage increases, the membrane flux increases and the specific energy consumption decreases. Moreover, the fouling of cation-exchange membrane was also discovered after the desalination of IL. The deposits on the surface or into the membrane which is probably caused by [Bmim]+ was characterized by scanning electron microscopy, elemental analysis and Fourier transform infrared.

Experimental Study on Electronic-Controlled High Pressure Common Rail Diesel Engine Fueled with Biodiesel

The performance tests of an electronically controlled high pressure common rail diesel engine and of the car mounted with an engine of this type fuelled by biodiesel–diesel mixed fuel with different mixing ratios are conducted, and its power outputs, fuel economies and emissions are measured and compared with the one of diesel operation. The results indicate that: when the load is 2200 r/min, the effective specific energy consumption decreases, NOx emission increases; smoke emission decreases at high load and keeps almost no change at low and middle loads; HC emission decreases at low and middle loads and keeps the same at high loads, and CO emission maintains the same; at full load characteristics, the power output increases slightly, HC and smoke emissions decrease, CO and NOx emissions increase.

Shrimp Drying Characterizes Undergoing Microwave Treatment

In this paper, a laboratory microwave oven was used to dry the shrimp, applying microwave power in the four levels of 200, 300, 400 and 500W. Results indicated that drying took place in the falling rate period. The drying rate increased with drying microwave power, but decreased with moisture content. The effective diffusivity varied from 1.54×10-10 to 1.43×10-9m2/s. About 22.54% increase in drying efficiency and about 28.94% (0.937MJ/kg[H2O]) decrease in specific energy consumption could be obtainable by increasing the microwave power from 200 to 500W.

Certain trends in power engineering at the beginning of XXI century

The changes in the modern power generating sector are relatively conservative in nature. As long before, the leading role belongs to fossil fuels. The main tendency is the increase of effectiveness of energy utilization and decrease of specific energy consumption in all sectors of economy. Simultaneously, the diversification of energy sources due to wider use of nontraditional and hard-to-develop sources is observed. The share of primary resources subjected to deep chemical processing, as well as the role of secondary energy sources increases. Active displacement of primary and secondary hydrocarbon processing to their production sites takes place. As the consequence of increasing power consumption in all spheres of manufacturing and life, we see fast growing available power and power dependency in all fields of human activity. Uninterrupted power supply is becoming a critical condition for normal life in modern world. The tendency for decentralization of power supply and reliable preservation of energy production capacities is enhancing.

6BTA 5.9 G2-1 Cummins engine performance and emission tests using methyl ester mahua ( Madhuca indica) oil/diesel blends

Neat mahua oil poses some problems when subjected to prolonged usage in CI engine. The transesterification of mahua oil can reduce these problems. The use of biodiesel fuel as substitute for conventional petroleum fuel in heavy-duty diesel engine is receiving an increasing amount of attention. This interest is based on the properties of bio-diesel including the fact that it is produced from a renewable resource, its biodegradability and potential to exhaust emissions. A Cummins 6BTA 5.9 G2- 1, 158 HP rated power, turbocharged, DI, water cooled diesel engine was run on diesel, methyl ester of mahua oil and its blends at constant speed of 1500 rpm under variable load conditions. The volumetric blending ratios of biodiesel with conventional diesel fuel were set at 0, 20, 40, 60, and 100. Engine performance (brake specific fuel consumption, brake specific energy consumption, thermal efficiency and exhaust gas temperature) and emissions (CO, HC and NOx) were measured to evaluate and compute the behavior of the diesel engine running on biodiesel. The results indicate that with the increase of biodiesel in the blends CO, HC reduces significantly, fuel consumption and NOx emission of biodiesel increases slightly compared with diesel. Brake specific energy consumption decreases and thermal efficiency of engine slightly increases when operating on 20% biodiesel than that operating on diesel.

An experimental study on the performance and exhaust emissions of a diesel engine fuelled with soybean oil methyl ester

In order to optimize the application of biodiesel for diesel engines, the emissions, fuel economies, and power performances of diesel, soybean oil methyl ester, and its blends with diesel from 10 to 80wt% were compared and analysed by bench tests of a supercharged direct injection (DI) diesel engine. The exhaust emissions (smoke density, NO x, CO, and HC), the brake specific fuel consumption rate, the specific energy consumption rate, and the brake power and torque were investigated under different engine loads and speeds. Experimental results show that, compared with diesel fuel, with increase in the soybean oil methyl ester percentage in the blends, smoke density and HC decrease while NO x emissions increase, CO increases under full load at 2000r/min but decreases at 3000r/min, specific energy consumption decreases and brake specific fuel consumption increases under different loads at 2200r/min, and brake power and torque increase at different speeds under full load. A biodiesel content of 20wt% is an optimum compromise between increased NO x and reduction in smoke density.

Sea water desalination by reverse osmosis: the true needs for energy

Almost half the exploitation costs of sea water reverse osmosis plant is affected to the electricity costs. Therefore, it's crucial to control those, and firstly to evaluate it. Each case should be treated independently, since the need in electricity depends on different factors: sea water characteristics, values taken for RO sizing parameters, electromechanical components efficiency . and, last but not least, choice of the system for hydraulic energy recovery of the concentrate. Energy recovery devices are an important part of any sea water reverse osmosis system, and any future decrease in specific energy consumption is dependent upon the further development and improvement in the performance of such devices. Recent technological innovations, such as energy recovery turbine, are required to reduce and improve the energy consumption. One of the simplest methods to operate a sea water RO unit is to run the pump at constant speed, to obtain the required membrane feed pressure through a feed throttle valve, and to recover the remaining brine energy via a Pelton turbine. Increasing hydraulic performances of Pelton turbines requires the optimisation of all components, taking into account their coupling. Until now the development of Pelton turbines has relied almost entirely on experimental and empirical knowledge and has not benefited from numerical flow simulation. This is mainly due to the fact that until now CFD simulations of free surface flows have not been fully validated and were impractical in an industrial environment, mainly due to the large computing time and resources that are needed. The numerical codes are still under development and, as with all CFD methods, have to be evaluated and validated before they can be used as standard tools in design. The highly successful use of CFD in Francis and Kaplan turbines has brought benefits of improved performance, more rapid and less risky design processes, large reduction in the need for empirical methods and reduced need for model and prototype tests. It is natural that these modern sophisticated design tools should now be adapted for use in Pelton turbines.

Drying Characteristics of Cotton Lint in a Recirculating Fixed-Bed Dryer with a Condenser

The effects of gas velocity (0.094−0.189 m/s), gas temperature (60−120 °C), cooling water flow rate (4.8 × 10-3−9.0 × 10-3 kg/s), and the cooling method (direct or indirect) on the drying characteristics (drying rate and specific energy consumption) of cotton lint in a 0.15-m-inner diameter (ID) × 0.9-m-high recirculating fixed-bed dryer have been determined. The drying rate increases, but the amount of specific energy consumption decreases, as the air temperature increases. With the direct cooling method, the drying rate increases as the cooling water flow rate increases. Further research is required to investigate the drying rate and the specific energy consumption as a function of the direct and indirect cooling methods.

Microwave Drying of Parsley: Modelling, Kinetics, and Energy Aspects

Parsley (Petroslinum crispum Mill.) leaves were dried in a 900 W 2450 MHz domestic microwave oven to assess the effects of material load on drying time, drying rate, drying efficiency, and specific energy consumption. Microwave drying experiments with different material loads ranging from 64·30 to 128·57 g were performed at microwave power cycle of 9 s on/9 s off at 900 W microwave output power. Drying took place mainly in constant rate and falling rate periods. A relatively long constant rate period was observed after a short heating period. Among the 11 mathematical models tested to fit the drying rates of parsley leaves, the Midilli et al. model with drying rate as a log–log and linear function of time gave the best fit for all the data points. The value of the drying coefficient k decreased with the increase in the dried material load. The multiple regression on the coefficients of the Midilli et al. model for the effects of material load being dried gave the successful results and showed to satisfactorily represent microwave drying kinetics of parsley leaves for the material loads between 64·30 g and 128·57 g. Increasing the material load resulted in a considerable increase in drying efficiency and a significant decrease in specific energy consumption. About 9·5% increase in drying efficiency and about 18% (0·92 MJ kg−1 [H2O]) decrease in specific energy consumption could be obtainable by increasing the material load from 64·30 to 128·57 g.

The work exchanger for reverse osmosis plants

Energy recovery devices are an important part of any seawater reverse osmosis system, and any future decrease in specific energy consumption is dependent upon the further development and improvement in the performance of such devices. We discuss and describe a new promising concept of energy recovery based on the pressure work exchange principle. In this device a rotating member comprising a multiplicity of double-sided free sliding ball pistons performs the pressure exchange between the differently pressurized fluids. The technical characteristics of the rotary work exchanger and the predicted performance after making a qualitative comparison with other types of energy recovery devices are presented.

Prognosen in der chemischen Technik

AbstractForecasts in the chemical industry. Forecasts of the energy demand in the Federal Republic of Germany for 1985 predicted figures which were, in some cases, more than 100% higher than the actual consumption figures, due among other things to an unforeseen decrease in specific energy consumption, e. g. in the chemical industry to about half of that in 1960. Since 1973 the overall energy consumption in the chemical industry has remained almost unchanged at some 15 million t/year coal equivalents in spite of increased production. In future forecasts, these possible divergences between economic growth and energy consumption will have to be given far greater attention. In 1977/1978 forecast, figures were calculated for the material flow from the raw material to the end products in selected fields in the chemical industry by means of a simulation model. Some of these forecasts show satisfactory agreement, while some of them deviate to a greater extent from the actual production figures, partly due to unexpected drastic changes in import quotas for some basic chemicals and intermediates.