Specific Energy Cost Research Articles

In-Operando X-ray Tomography Studies of Dendrite Formation in Zinc-Air Batteries

Rechargeable aqueous zinc-air systems are remarkably attractive power sources because of high specific energy, safety, environmental compatibility and low cost. However these systems are still under development and suffer from sufficiently short cycle life that prohibits their use for large electrical storage applications requiring several thousand cycles. One of the key factors responsible is dendritic growth when the system is recharged. Dendrites can grow sufficiently wide to penetrate the separator between the anode and the cathode and cause an internal short-circuit. Despite the substantial work accomplished in studying of zinc dendrite formation there are only few reports available on real time imaging of dendrite growth.Recent developments in X-ray micro/nano tomography have demonstrated the great advantage of the technique for non-destructive ex- and in-situ characterisation of materials and devices for electrochemical energy storage and generation. We used synchrotron x-ray tomography to investigate the mechanism and kinetics of dendrite formation during zinc-air system operation. The dendrite growth was analysed in-operando in radiography mode while three-dimensional image of dendrites covering the electrode surface was reconstructed from multiple tomographic projections ( Figure 1).

MANUFACTURING AND PERFORMANCE EVALUATION OF A LOCAL ANIMAL FEED HORIZONTAL MIXER

The present research was carried out to manufacture and evaluate some operating parameters affecting the performance of an animal feed horizontal mixer to improve product quality. The mixer performance was studied as a function of change in material batch size and mixing time. Performance evaluation of the horizontal mixer was carried out in terms of mixing homogeneity, coefficient of variation, specific energy and mixing cost. The experimental results revealed that coefficient of variation; mixing homogeneity; specific energy and mixing costs were in the optimum region under the following conditions: - The mixer shaft is designed at a diameter of 80 mm. - Operate the mixer at a batch size of between 700 to 850 kg. - The mixing time should be of between 15 to 20 minutes.

High Capacity Li/S Battery for Advancing Commercialization

Rechargeable Li/S batteries are promising candidates for portable electronics, electric vehicles and energy storage system due to their high specific energy and low cost. Many researchers have reported remarkable results in this area, but there are still huge obstacles for commercialization in terms of sulfur loading level for higher specific energy and higher stabilization for lithium metal anode. To solve these problems, we have researched with two aspects. One is attempting to realize highly loaded sulfur cathode with large utilization by impregnating carbonaceous conductive network with nano-sized sulfur. The other is preventing sulfide-shuttle by separator coated with negatively charged material. Using nano-sized sulfur has advantages not only for increasing networks for sulfur-carbon, but also for obtaining enough space against expansion during lithiation. Furthermore, the conductive network of sulfur-carbon can be more stably maintained with cycling which gives long life span as compared to micro-sized sulfur cathode. Nano-sulfur was fabricated using the conventional milling process in water added with glycerol. Ketjen Black with high surface area and aqueous PVP-PEO mixture were used as a conductive material and binder respectively. Finally, cathode electrodes were prepared with high sulfur contents of 70 wt% and elevated sulfur loading of 3.0 mg/cm2. Electrochemical measurements were carried out using CR2032 coin-type cell system. Initial specific capacity and capacity retention were more than 1,000mAh/g(sulfur) and 80% after 100 cycle respectively. Adapting separator coated with negatively charged moiety significantly decreased the over-charging. This phenomenon can be interpreted as an effect of the negative moiety on separator to repulse the soluble polysulfides which move toward the surface of anode. Detailed properties up to 300 cycles for pouch cell will be discussed. We believe that the nano-sized sulfur and separator coated with negative moiety can be helpful to advance the commercialization of lithium sulfur battery with high specific energy density more than 300Wh/kg.

MANUFACTURE AND PERFORMANCE EVALUATION OF A COMBINATION MACHINE FOR CHOPPING AND MILLING ARUNDO DONAX (PART II)

The aim of the present work was to manufacture and evaluate the performance of a combination machine to be suitable for chopping and milling the Arundo donax stalks so as to use the final product in many industrial applications such as: making compost to improve soil properties, energy source (direct burning and biogas generation) and compressed wood. The performance of the combination machine was studied under the following parameters: drum speed, moisture content and feed rate. The performance of the manufactured machine was evaluated taking into consideration the following indicators: cut length distribution, machine productivity, fineness degrees, specific energy and operational cost. The experimental results reveal that the highest values of cut length percentage < 2 up to 4 cm, machine productivity and fine degree were (78.95%, 600 kg/h and 82.87%) respectively, while the lowest values of the specific energy and operational cost were (71.08 kW.h/Mg and 33.33 L.E/Mg), respectively under the following conditions: drum speed of about 1300 rpm, stalks moisture content of 14% with adjusting feed rate at 700 kg/h.

A NEW MACHINE FOR PRODUCING BUTTER TO SUIT SMALL PROJECTS

The aim of the present study is to manufacture and evaluate batch butter churning machine for butter and buttermilk production from sweet or fermented cream. The new butter making machine consists of five main parts: power source, transmission system, collection cream vessel and cooling unit. The cooling unit consists of five parts: evaporator, expansion valve, condenser, fan, receiver tank, and compressor. Laboratory experiments were conducted to optimize cream loading ratio, churning time and churning temperature. While the churn machine performance was evaluated in terms of butter and buttermilk amounts,buttermilk fat percentage, churn efficiency, specific energy and operational cost of butter churn. The experimental results reveal that the churning machine is recommended to be used to give the highest butter production of 21.20 kg/h with lower specific energy and operational cost of 23.11 kW.h/Mg and 188.21 L.E/Mg, respectively at cream loading ratio of 45 kg/h, churning temperature of 6° C and churning time of 15 min under constant fan speed of 600 rpm.

CONSTRUCTION AND PERFORMANCE EVALUATION OF A CENTRIFUGAL MILK SEPARATOR

The aim of the present study is to construct and evaluate a centrifugal milk separator for cream and skim milk production. The milk separator consists of five main parts: power source, transmission system, collection milk vessel, centrifugal separation unit and production collectors. The centrifugal separation unit consists of three parts: housing, separated discs with totally number of 40 conical discs collect and fix in the housing together and stuck base, which fastening the conical discs and the housing together through a stud and Hex. Hd. Nut. Laboratory experiments were conducted to optimize milk feeding rate, separation rotating speed and raw milk temperature degree. While the separator performance was evaluated in terms of cream and skim milk amounts,skim milk fat percentage, separation efficiency, specific energy and operational cost of milk separation. The experimental results reveal that the milk separator is recommended to be used under the following conditions to give the highest cream amount of 35 kg/h with lower specific energy and operational cost of 25.14 kW.h/Mg and 228.60 L.E/Mg, respectively: - Milk feeding rate to the conical separating unit of 400 kg/h. - Separation rotating speed of 8000 rpm. - Temperature degree for the raw milk of 37° C.

Integration of Multiple in-House Heat Stations into One Energy Flexible Heat System - Part 2

Integration of several in-house heat stations containing of multiple boilers of different capacity and energy carriers can be economical profitable. This study contains further analyze and development of previous work by Riise and Sørensen [1-3]. Boiler start-up costs effect of the overall energy cost has been investigated and found to have an impact of boiler configurations in a system based on lowest specific running energy cost. A study of operational hours of boilers indicates if boilers can be dismounted form the integrated system. It is also performed simulations for lowest energy consumption instead lowest energy cost. Finally a heat pump model is introduced and analyzed. Introduction of the heat pump reduces the total energy cost even if the heat sink is increased with a fourth building.

DEVELOPMENT OF RICE MILLING MACHINE FOR DIFFERENT RICE VARIETIES TO IMPROVE PRODUCT QUALITY

The present research was carried out to develop and estimate some operating parameters and affecting the performance of a rice milling machine to improve product quality. The rice milling machine was developed by adding two units: cleaning unit to remove chaff and other foreign materials from rice grains before the milling operation and feed unit to adjust rice feed rate. The performance of the developed milling machine was studied under the following parameters: feed rate, drum speed, and grain moisture content in terms of overall machine efficiency, total grains losses, machine productivity, required power, specific energy and criterion cost. The experimental results reveal that the highest values of machine productivity and overall machine efficiency were 1.08, 1.17 and 1.35 Mg/h; and 95.00, 95.38 and 95.66 % for Sakha-101, Giza-171 and Sakha-105 varieties, respectively, while the lowest values of required power and specific energy were 13.0, 13.4 and 13.8 kW; and 17.40, 15.68 and 13.85 kW.h/Mg, respectively, for the same rice varieties, furthermore the lowest values of both operational and criterion costs were 8.53, 7.87 and 6.82 L.E./Mg; and 35.96, 31.96 and 29.38 L.E./Mg, respectively, for the same rice varieties. Results of mechanical analysis of the manufactured cleaning and feeding units reveal to the following: Sieve speed, sieve tilt angle and cleaning air velocity of about 400 rpm, 4.0 deg and 6.5 m/s. Mechanical feeding rate of 1.4 Mg/h for Sakha-101 variety and 1.6 Mg/h for both Giza-171 and Sakha-105 varieties. From the experimented results, it could be concluded that the optimum operating parameters for the developed milling machine were found at: Drum speed of about 800 rpm for Sakha-101 and 850 rpm for both Giza-171 and Sakha-105 varieties. Grain moisture content of about 14 % for Sakha-101 and 15 % for both Giza-171 and Sakha-105 varieties.

AERODYNAMIC ANALYSIS AND PERFORMANCE EVALUATION OF RICE MILLING MACHINE

Experiments were carried out to derive aerodynamic analysis and evaluate the performance of a rice milling machine. Physical and engineering properties of grains under study have to be considered to study their effect on the performance of the milling machine. The performance of the milling machine was studied under the following parameters: feed rate, drum speed, concave clearance and seed moisture content. Performance evaluation of the machine was carried out in terms of overall machine efficiency, total grains losses, machine productivity, required power, specific energy and criterion cost. The experimental results reveal that the highest values of machine productivity and overall machine efficiency were 925 kg/h and 92.38%, while the lowest values of required power and specific energy were 9.2 kW and 11.95 kW.h/Mg, furthermore the lowest values of both operational and criterion costs were 9.15 L.E./ Mg and 48.05 L.E./ Mg, respectively. The optimum operating parameters of milling machine were found at 10 m/s air velocity by using 1.4 Mg/h feed rate with 10 mm concave clearance and 850 rpm drum speed at 16 % grain moisture content.

ChemInform Abstract: Nanostructured Sulfur Cathodes

AbstractReview: 109 refs.

MANUFACTURE AND PERFORMANCE EVALUATION OF A LOCAL UNIT FOR PRODUCING COMPOST TEA

Experiments were carried out to manufacture and evaluate the performance of a local unit for producing compost tea. The performance of the manufactured unit was studied as a function of change in material dilution percentage, temperature degree, air pressure and fermentation period. Performance evaluation of the manufactured unit was carried out in terms of extraction efficiency, unit productivity, required power, specific energy and operational cost. The experimental results reveal that that the highest values of unit productivity and extraction efficiency were (1.64 l/h and 95.33%), while the lowest values of specific energy and operational cost were (0.26 kw.h/l and 2.29 L.E./l) respectively under the following conditions: § The use of the manufactured unit for producing compost tea. § Operate the manufactured unit at a temperature degree of about 25o C. § Adjust the air pressure at 1.5 kg/cm2. § Operate the manufactured unit at a fermentation period of about 24 h. § Adjust the dilution percentage at about 1:10.

Nanostructured sulfur cathodes

Rechargeable Li/S batteries have attracted significant attention lately due to their high specific energy and low cost. They are promising candidates for applications, including portable electronics, electric vehicles and grid-level energy storage. However, poor cycle life and low power capability are major technical obstacles. Various nanostructured sulfur cathodes have been developed to address these issues, as they provide greater resistance to pulverization, faster reaction kinetics and better trapping of soluble polysulfides. In this review, recent developments on nanostructured sulfur cathodes and mechanisms behind their operation are presented and discussed. Moreover, progress on novel characterization of sulfur cathodes is also summarized, as it has deepened the understanding of sulfur cathodes and will guide further rational design of sulfur electrodes.

Hadera desalination plant two years of operation

In May 2010, IDE Technologies Ltd. completed the Hadera plant, one of the world’s largest operating seawater reverse osmosis desalination facilities. This was a milestone event for the desalination industry clearly confirming IDE’s clear leadership of the mega-sized desalination market. IDE’s design for the Hadera plant utilizes the three center design (pumping, membrane, and energy recovery centers), cascade boron treatment, and other technologies to decrease energy requirements and increase overall efficiency. These technologies have enabled Hadera to achieve one of the lowest ever costs for high-quality desalinated water.One of the main challenges met in the design of the plant was the minimization of the energy cost by utilizing the different electricity tariffs over a 24-h period, as well as a variable operation production regime. Moreover, the specific energy cost was further reduced by taking advantage of the common pressure center design during the peak electricity periods. Hourly variations in production from 100 to 40% are typical figures in day-to-day plant operation. The brackish reverse osmosis system patented cascade design demonstrates the system’s ability to produce water with low boron content, minimum operational risks, and at the highest recovery ratios. The posttreatment system design is optimized to produce high-quality potable water in terms of the required alkalinity, hardness, pH and langelier saturation index through intensive rehardening, while still optimizing capital and operational costs. Recently the plant completed its second year of operation. This article describes the current plant operation section-by-section.

Energetics and mechanics of running men: the influence of body mass

We investigated the relationship between mechanical and energy cost of transport and body mass in running humans. Ten severely obese (body mass ranging from 108.5 to 172.0kg) and 15 normal-weighted (52.0-89.0kg) boys and men, aged 16.0-45.8years, participated in this study. The rate of O(2) consumption was measured and the subjects were filmed with four cameras for kinematic analysis, while running on a treadmill at 8kmh(-1). Mass specific energy cost (C (r)) and external mechanical work (W (ext)) per unit distance were calculated and expressed in joules per kilogram per meter, efficiency (η) was then calculated as W (ext)×C (r) (-1) ×100. Both mass-specific C (r) and W (ext) were found to be independent of body mass (M) (C (r)=0.002M+3.729, n=25, R (2)=0.05; W (ext)=-0.001M+1.963, n=25, R (2)=0.01). It necessarily follows that the efficiency is also independent of M (η=-0.062M+53.3298, n=25, R (2)=0.05). The results strongly suggest that the elastic tissues of obese subjects can adapt (e.g., thickening) to the increased mass of the body thus maintaining their ability to store elastic energy, at least at 8kmh(-1) speed, at the same level as the normal-weighted subjects.

Application of solar photoelectro-Fenton technology to azo dyes mineralization: Effect of current density, Fe2+ and dye concentrations

Independent solutions of 2.5L of the azo dyes Acid Red (AR88) and Acid Yellow (AY9) in Na2SO4 with low contents of catalytic Fe2+ at pH 3.0 have been degraded by electro-Fenton (EF) and solar photoelectro-Fenton (SPEF) using a recirculation flow plant containing a one-compartment cell with a boron-doped diamond (BDD) anode and an air-diffusion electrode (ADE) as cathode, each one of 20cm2, coupled with a solar photoreactor. The EF process yields rapid decolorization, but poor total organic carbon (TOC) removal because azo dyes are oxidized with hydroxyl radicals formed at the BDD anode from water oxidation and in the bulk from Fenton's reaction between added Fe2+ and H2O2 generated at the ADE cathode, leading to persistent carboxylic acids like oxalic acid that is the major component of final electrolyzed solutions. The quick photolysis of Fe(III)-oxalate complexes by UV light of solar irradiation explains the higher oxidation power of SPEF giving almost total mineralization. The incident UV light also photodecomposes several N-derivatives favoring the release of NH4+ ion in front of NO3− ion and the loss of volatile N-compounds. The effect of current density (25–150mAcm−2), Fe2+ concentration (up to 0.8mM) and dye concentration (between 50 and 200mgL−1 TOC) on the degradation rate, mineralization degree, mineralization current efficiency and specific energy cost of the SPEF treatment is examined. The application of this technology is more viable at lower current density and higher azo dye content operating at optimum 0.5mM Fe2+, since greater efficiency and smaller specific energy cost are obtained for the mineralization process.

ENGINEERING STUDIES ON THE FACTORS AFFECTING THE PERFORMANCE OF SHELLING AND GRADING CORN MACHINE

The performance of an Italian made combined machine was tested and evaluated for shelling and grading two different Egyptian corn crop varieties. Whereas, the optimum design, and operating parameters were determined in order to increase the mechanical shelling and grading efficiency and machine productivity. The crop was feed at a constant rate of 25 kg and at the grains recommended moisture content range of 12-14% (d.b). The shelling unit of the machine was deduced at four different drum speed levels (from 370 up to 820 rpm, those corresponding drum linear speeds from 4.84, up to 10.74 m/s). Also, shelling unit was tested under three concave clearance levels (32, 42 and 52mm). While, the grading unit deduced at different cylindrical screen speed levels (from 55, up to 95 rpm corresponding to linear cylinder speeds from 1.38, up to 2.39 m/s). The grading unit was also tested versus different cylindrical screen inclination angle up to 9 degrees. The tested machine performances were evaluated in terms of the grading and cleaning efficiency. In addition, costs per unit weight of production and energy unit requirements were estimated and compared with the traditional shelling and grading methods of corn crop. The obtained results revealed the following important points: The optimum parameter levels for the mechanical shelling operation were drum speed of 670 rpm (8.77 m/s) and concave clearance of 42 mm. These parameters levels were recommended to match the performance of the grading unit. The promising parameters levels for operating the grading both tested crop varieties were 80rpm (2.00 m/s) for cylindrical screen speed and 3 degrees for inclination angle.As operating at the optimum parameter levels the highest values of grading efficiency (83.68 and 82.84 %), grading cleanliness (77.78 and 77.18 %), and machine capacity (0.51 and 0.47 ton/h) were achieved. for both tested corn varieties, SC10 and TC310 respectively. Also, the lowest values of specific energy consumption (25.94 and 29.29 kW.h/Mg) and cost (76.12 and 78.28 LE/ton) for both tested corn varieties, SC10 and TC310, respectively.

Body Weight and Allometric Data and Diet ‐ Experimental Study

In this study we evaluate the possible changes of body weight (BW) and allometric data in relation with diet composition. Two groups of 20 Wistar male rats 4 weeks old were used. One group was maintained with no manipulation (control), the other was submitted to the administration of a diet rich in sucrose and poor in proteins and lipids during 4 weeks (test). After 4 weeks all the animals were sacrificed. The body weight was measured. The index for each organ was determined (Ixw). It was also determined the food ingest rate (FIR), the water intake rate (WIR), the inhalation rate (INR), the specific minimum energy cost (SMEC) and body surface area (BSA). The BW, Ixw and allometric data given for a confidence interval of 95% were the following results. For the control group: BW from 170.81 to 196,09, Ilw from 0,0426 to 0.0481, Ikw from 0.0036 to 0.0044 and Isw from 0.0038 to 0.0058, FIR from 11.545 to 12.400, WIR from 0.021 to 0.024, INR from 95.443 to 105.733, SEMEC from 19.209 to 21,140 and BSA from 357.233 to 3888.012. For the test group BW from 32.80 to37.37, Ilw from 0.051 to 0.059, Ikw from 0.006 to 0.007 and Isw from 0.012 to 0.014, FIR from 4.542 to 4.879, WIR 0.0048 to 0.0053, INR from 25.461 to 28.119, SMEC from 5.563 to 6.109 and BSA from 121.974 to 132.382. This results indicate that alterations in nutrition can modify basic physiologic parameters and interferer with the studies of some experimental models.

Steam driven large multi effect MVC (SD MVC) desalination process for lower energy consumption and desalination costs

It has been published and demonstrated in operating plants that the low-temperature multi effect desalination process (LT MED) when operated on turbine backpressure steam requires minimal energy consumption yielding specific desalination energy costs approaching values of optimal RO energy costs. However due to variations in electricity demand, the operation of large steam turbines at base load is in most cases impractical. As a result, in order to allow variations in electricity supply and full capacity of the desalination extraction, steam extracted from the turbines at higher pressures than the back pressure is commonly used. The extraction steam pressure of these turbines is in the range of 1.5–4.5 barg. (Typically as required for process steam at refineries and for MSF desalination plants). The LT MED process when utilizing such extraction steam incorporates thermo compressors (steam ejectors) in order to take advantage of the excessive extraction steam pressure, thereby increasing the economy ratio of the MED (decreasing energy consumption). Thermo compressors (ejectors) as a rule have a relatively low adiabatic efficiency, thus limiting the potential of the MED to increase the economy ratio even more. In this paper an approach of using a novel large centrifugal compressor driven by an auxiliary steam turbine utilizing the extraction steam is incorporated instead of the thermo compressor for large LT MED plants. The centrifugal compressor and auxiliary turbine having a much higher efficiency than the thermo compressor results in significant energy savings, thus lowering the desalination costs. This paper will also describe the thermodynamic advantages, the specific investment and desalination costs comparison, and the resulting desalination cost reduction potential of the steam-driven multi effect MVC process.

Chemical Kinetics of the Removal of Formaldehyde in Dielectric Barrier Discharges

A time and space averaged chemical kinetics model in the removal of formaldehyde via a dielectric barrier discharge at atmospheric pressure and ambient temperature was reported.An analysis with regard to the discharge time evolution of the different main species was also included,and the results of the analysis showed that O~·and OH~·radicals,especially OH~·radicals,were the key species for the removal of HCHO.The role played by the first electronically excited metastable state N_2(A~3∑_u~+)was clarified that,in air,the chemical attacks of O_2 and H_2O by N_2(A~3∑_u~+) produced much more O~·and OH~·radicals.In nitrogen,N_2(A~3∑_u~+)made a great contribution in the removal of HCHO. Specific energy cost and the molar ratio of n_(CO_2)/n_(CO) for HCHO removal at different HCHO initial concentrations and gas flow rates were also discussed.Specific energy cost at high HCHO initial concentration was lower than that at low HCHO initial concentration.If input discharge energy density60 J·L~(-1),n_(CO_2)/n_(CO) at low HCHO initial concentration was higher than that at high HCHO initial concentration.

Advanced MED process for most economical sea water desalination

The low temperature horizontal tube multi-effect desalination (MED) process is thermodynamically the most efficient of all thermal distillation processes. A comprehensive multi-disciplinary development and design approach resulted in prevention of corrosion and scale formation on the plant’s heat transfer surfaces. It also allows the successful and most economical use of aluminum alloys for heat transfer tubes, as well as carbon steel epoxy coated shells for the evaporator body. The ability to use economically low grade heat, such as waste heat, exhaust steam from power station turbines as the primary heat source for MED, yields very low specific energy costs for sea water desalination. Recent developments of very economical low temperature deep pool nuclear heat reactors, when acting as the primary energy source for large MED plants, yield very low specific desalination energy costs. The combination of economical specific MED plant costs with low energy cost, together with the inherent durability of low temperature MED avoiding the necessity of comprehensive sea water pretreatment (such as with RO plants) make the MED process one of the best candidates for safe and durable large capacity economical desalination options. This paper describes the design principles and various energy considerations that result in this uniquely economical MED process and plant. It also provides an overview of various cases of waste heat utilization, and cogeneration MED plants operating for many years.