Rate Of Liquefaction Research Articles

Gravitational effects on liquefaction systems for Lunar and Mars exploration

There is interest at NASA, other space agencies, and industry, in the liquefaction of fluids produced through in-situ processes on the surfaces of the Moon and Mars. A multi-center team at NASA recently considered multiple different refrigeration cycles and refrigeration integration methodologies and how these might fit into early liquefaction plants for NASA's exploration initiatives and In-Situ Resource Utilization (ISRU). The rate of liquefaction for ISRU is quite slow in comparison to large scale terrestrial applications. These studies concluded that, for both structural and heat spreading reasons, integrating the refrigeration tubing on the surface of the storage tank wall is an attractive path to pursue in the near term. In order to develop a technology development path and inform investors, it was desired to investigate the sensitivity of gravity of the processes involved.An analysis of the condensation processes within the tank is performed. The objective is to determine the sensitivity of liquefaction to gravitational effects. The heat transfer mechanisms include forced convection heat removal to the refrigeration system (or cryocooler), conduction through the tank wall heat exchanger, and convection and condensation on the inner tank wall. Gravity affects the liquefaction process via condensate liquid drainage, natural convection in the ullage, and the shape of the liquid–vapor interface within the tank. Analysis of these mechanisms shows that while there is some sensitivity to gravitational level in general, within the bounds of current interest (rate of liquefaction appropriate to Lunar and Martian applications, and cooling capacity of the cryocooler), this sensitivity of liquefaction to gravity is quite small. Thus, system level testing on the Earth should suffice for the performance prediction and demonstration of liquefaction operations as applicable to Lunar and Martian applications.

Macroalgae (Ulva reticulata) derived biohydrogen recovery through mild surfactant induced energy and cost efficient dispersion pretreatment technology

Currently identification of alternate fuel is the key area of research under progress to overcome the depletion of fossil fuels, meet the domestic and industrial requirements. Generation of hydrogen, which is a clean fuel gas can solve various environmental related problems. Extensive research is being carried out to increase production of hydrogen through different substrates. This study aims to increase the production of hydrogen from Ulva reticulata (a macroalgal biomass). Initially, the biomass is pretreated mechanically with disperser and a biosurfactant, namely rhamnolipid in order to increase the solubilization of the biomass. The rate of COD liquefaction increased from 14% to 25% with the addition of biosurfactant to the macroalgal biomass, which is further treated mechanically using a disperser. The disperser rotor speed of 12,000 rpm and the specific energy input of 1175 kJ/kg TS (Total Solids) with the disintegration time of 30 min and biosurfactant dosage of 0.075 g/g TS were considered as the optimum parameters for the effective liquefaction of the macroalgal biomass. Approximately 3500 mg/L of the biopolymers were released after the combinative pretreatment (using disperser and biosurfactant). About 80 mL biohydrogen/g COD (Chemical Oxygen Demand) was generated when the biomass was pretreated with both the disperser and biosurfactant while the biomass pretreated with the disperser alone generated just 30 mL biohydrogen/g COD and the untreated biomass generated 5 mL biohydrogen/g COD. Thus, it can be concluded that Ulva reticulata can be utilized effectively to generate biohydrogen.

Efficiency of blended polyhydric alcohols solution on liquefaction of oil palm trunk (Elaeis guineensis Jacq.)

The oil palm tree is a monocotyledon, and the chemical composition varies relative to the part of its trunk. Therefore, the purpose of this study was to investigate the relationship between the chemical composition in different parts of an oil palm trunk and the rate of liquefaction. PEG#400/glycerol (4:1, w/w) was the liquefying reagent with 2% sulfuric acid as a catalyst. Liquefaction was done at the optimum conditions of liquor ratio, temperature (130 to 180 °C), and reaction time (30 to 120 min). The results revealed that the rate of liquefying was dependent on the part of the trunk. The inner zone in the top parts of the trunk had the least amount of lignin and lowest crystallinity. Thus, these parts could be liquefied faster than the other parts of the trunk. According to FTIR, XRD, and 13C NMR analyses, the amorphous polymer content (comprised of lignin, hemicellulose, and disordered zones of cellulose and starch) mostly degraded at the low temperature of 140 °C for 30 min, while the crystalline regions required higher temperature (180 °C). Increasing the temperature had stronger effects than extending reaction time or the liquor ratio. Furthermore, excess in these reaction parameters caused re-condensation of the degraded liquefied products.

Cryocooler based helium liquefier development-A practical usage

A helium liquefier using a 1.5 watt at 4.2KGifford Mac Mohan (GM) cryocooler was developed at IUAC having a liquefaction capacity of 17.4 litres per day (lpd) at STP. This standalone setup could not be used for any other experimental facility which requires liquid helium for its functioning and so another portable experimental liquefier was designed and fabricated using the same technology, which can be used to hook up very easily using its liquid inlet line port. In the present experimental demonstration setup the cryocooler liquefier was hooked up to a commercial 1001 helium Dewar. The Dewar was cooled starting from room temperature with the cryocooler liquefier in 2 days and 50 litresof liquid helium was collected inside the Dewar. The measured production rate of liquefaction was 14.2 litres per day. Successful liquefaction of helium in such a portable setup opens up the door for using this technology for other experimental purpose requiring liquid helium.

Comparison of SPT and V s-based liquefaction analyses: a case study in Erciş (Van, Turkey)

Liquefaction which is one of the most destructive ground deformations occurs during an earthquake in saturated or partially saturated silty and sandy soils, which may cause serious damages such as settlement and tilting of structures due to shear strength loss of soils. Standard (SPT) and cone (CPT) penetration tests as well as the shear wave velocity (V s)-based methods are commonly used for the determination of liquefaction potential. In this research, it was aimed to compare the SPT and V s-based liquefaction analysis methods by generating different earthquake scenarios. Accordingly, the Ercis residential area, which was mostly affected by the 2011 Van earthquake (M w = 7.1), was chosen as the model site. Ercis (Van, Turkey) and its surroundings settle on an alluvial plain which consists of silty and sandy layers with shallow groundwater level. Moreover, Caldiran, Ercis–Kocapinar and Van Fault Zones are the major seismic sources of the region which have a significant potential of producing large magnitude earthquakes. After liquefaction assessments, the liquefaction potential in the western part of the region and in the coastal regions nearby the Lake Van is found to be higher than the other locations. Thus, it can be stated that the soil tightness and groundwater level dominantly control the liquefaction potential. In addition, the lateral spreading and sand boiling spots observed after the 23rd October 2011 Van earthquake overlap the scenario boundaries predicted in this study. Eventually, the use of V s-based liquefaction analysis in collaboration with the SPT results is quite advantageous to assess the rate of liquefaction in a specific area.

Effects of lens extirpation with anterior vitrectomy on vitreous three-dimensional mesh structure.

To investigate the changes in vitreous gel structure after lens extirpation combined with anterior vitrectomy in rabbit eyes. Twenty-eight chinchilla rabbits were divided into three groups. The control group (Group I) included 16 eyes from eight rabbits who did not receive any treatment. Group II included 20 eyes from 10 rabbits that underwent lens aspiration only. Group III included 20 eyes from 10 rabbits that underwent lens aspiration combined with posterior capsulotomy and anterior vitrectomy. Eyes were harvested on the 30th and 60th day postoperatively, respectively. Changes in vitreous gel stretch length due to gravity and the rate of vitreous liquefaction were observed. The collagen content in the vitreous body was examined using the L-hydroxyproline test. Electronic microscopic images were obtained from each eyeball. On both the 30th and 60th day postoperatively, the vitreous gel length of group III was significantly shorter than group I and group II (P<0.05), while the rate of liquefaction of the vitreous body in group III was significantly higher than group I and group II (P<0.05). The collagen content in group III was also higher than that in group I and group II (P<0.05). Loss of vitreous gel mass is more likely to occur in the eyes of rabbits receiving anterior vitrectomy. Lensectomy combined with anterior vitrectomy may damage the stable three-dimensional mesh structure of collagen, which could aggravate vitreous gel liquefaction.

Proteolysis of Sardine (Sardina pilchardus) and Anchovy (Stolephorus commersonii) by Commercial Enzymes in Saline Solutions.

Fish sauce production is a very long process and there is a great interest in shortening it. Among the different strategies to speed up this process, the addition of external proteases could be a solution. This study focuses on the effect of two commercial enzymes (Protamex and Protex 51FP) on the proteolysis of two fish species traditionally converted into fish sauce: sardine and anchovy, by comparison with classical autolysis. Hydrolysis reactions were conducted with fresh fish at a temperature of 30 °C and under different saline conditions (from 0 to 30% NaCl). Hydrolysis degree and liquefaction of the raw material were used to follow the process. As expected, the proteolysis decreased with increasing amount of salt. Regarding the fish species, higher rate of liquefaction and higher hydrolysis degree were obtained with anchovy. Between the two proteases, Protex 51FP gave better results with both fish types. This study demonstrates that the addition of commercial proteases could be helpful for the liquefaction of fish and cleavage of peptide bonds that occur during fish sauce production and thus speed up the production process.

Cationic polyacrylamides increase the rate of liquefaction and hydrolysis of cornstarch

Cationic polyacrylamides (c‐PAMs) bind to starch granules and decrease the temperature for the onset of gelatinization by 8°C. c‐PAM increases the binding of α‐amylase to cornstarch; the rate of cornstarch hydrolysis also increases. By analogy to previous work on the c‐PAM promoted hydrolysis of cellulose, it is proposed that the polymer reduces the charge on the surface of starch through a charge‐patch mechanism. Because both enzyme and substrate are negatively charged, the bound c‐PAM reduces the charge repulsion experienced by the approaching enzyme, which leads to stronger enzyme‐substrate binding and faster hydrolysis. Overall, the c‐PAM reduces enzyme dose by up to 62% under the conditions used. There is a mirror image relationship between the viscosity of the medium and the hydrolysis rate, which allows optimization of these parameters with enzyme and c‐PAM dosage. Low c‐PAM levels increase viscosity by agglomerating the substrate, but the viscosity drops at higher c‐PAM concentration. © 2012 American Institute of Chemical Engineers AIChE J, 59: 79–83, 2013

Role of heat exchangers in helium liquefaction cycles: Simulation studies using Collins cycle

Energy efficiency of large-scale helium liquefiers generally employed in fusion reactors and accelerators is determined by the performance of their constituting components. Simulation with Aspen HYSYS ® V7.0, a commercial process simulator, helps to understand the effects of heat exchanger parameters on the performance of a helium liquefier. Effective UA (product of overall heat transfer coefficient U, heat transfer surface area A and deterioration factor F) has been taken as an independent parameter, which takes into account all thermal irreversibilities and configuration effects. Nondimensionalization of parameters makes the results applicable to plants of any capacity. Rate of liquefaction is found to increase linearly with the effectiveness of heat exchangers. Performance of those heat exchangers that determine the inlet temperatures to expanders have more influence on the liquid production. Variation of sizes of heat exchangers does not affect the optimum rate of flow through expanders. Increasing UA improves the rate of liquid production; however, the improvement saturates at limiting UA. Maximum benefit in liquefaction is obtained when the available heat transfer surface area is distributed in such a way that the effectiveness remains equal for all heat exchangers. Conclusions from this study may be utilized in analyzing and designing large helium plants.

Liquefaction of cellulose in the presence of phenol using p-toluene sulfonic acid as a catalyst

The kinetics of p-toluene sulfonic acid (PTSA)-catalyzed cellulose liquefaction in the presence of phenol were investigated at 130, 140 and 150 °C. The resulting liquefied products were also analyzed to evaluate the effectiveness of PTSA as a catalyst during the phenol liquefaction. The liquefaction rate of PTSA was slightly lower than that of sulfuric acid (SA), which was used as a reference catalyst, at each liquefaction temperature. The activation energies of the PTSA and SA catalysts during the phenol liquefaction of cellulose calculated using the Arrhenius equation were 34.5 and 35.5 kcal/mol, respectively. The chemical compositions of the ether extracts in the liquefied products were very similar to both catalysts. Methylene bisphenol and its isomers, which were the primary components in the ether extracts, comprise approximately 30% of the ether extract. The GPC curves of the 80% dioxane-soluble part of the liquefied product indicated that it consists of a remarkable amount of phenol-based trimers to hexomers. The average molecular weight and the polydispersity of the liquefied products were very similar after liquefaction using both catalysts; therefore, differences in the products produced using both catalysts used were not recognized. However the level of combined phenol in the liquefied product produced using the PTSA catalyst was approximately 50% lower than that of the SA catalyst. Although it is believed that this difference may cause retardation of the rate of liquefaction, further experiments are necessary to explain differences in the effectiveness of organic sulfonic acid catalysts during the phenol liquefaction of lignocellulosic biomass.

A Simple Method to Measure the Liquefaction Rate of Human Semen

The centrifugation method has been developed to measure the rate of liquefaction in normal human semen. This method is very simple, reliable and convenient. Evidence is presented here to show that the liquefaction rate at ice-bath temperature is much slower than the rate at room temperature.

Effects of the addition of spleen of skipjack tuna ( Katsuwonus pelamis) on the liquefaction and characteristics of fish sauce made from sardine ( Sardinella gibbosa)

The effects of the addition of spleen of skipjack tuna ( Katsuwonus pelamis), at levels of 0%, 10% and 20%, on the liquefaction and characteristics of fish sauce produced from the sardine ( Sardinella gibbosa) with different salt concentrations (15%, 20% and 25%) were monitored during fermentation for 180 days. Fish sauces prepared from sardine with spleen supplementation contained greater total nitrogen, amino nitrogen, formaldehyde nitrogen and ammonia nitrogen than did those without spleen addition throughout the fermentation. The rate of liquefaction was dependent on the amount of spleen added. Reduction of salt content accelerated the hydrolysis of fish protein during fermentation. The liquefaction rate of the lower salt-treated samples was generally faster than were those treated with higher salt content. Among all treatments, sardine with 25% spleen and 15% salt added exhibited the greatest protein hydrolysis, particularly at the early stages, suggesting the combined effects of autolysis and spleen proteinase. The greater liquefaction was coincidental with the development of browning as well as the increase in redness of liquid formed. An acceptability test revealed that the samples were different in colour, aroma, taste and overall acceptance ( p < 0.05). Fish sauce samples containing 20% salt, without and with 10% spleen addition had similar acceptabilities to commercial fish sauce. Therefore, the addition of spleen, as well as salt reduction, can accelerate the liquefaction of sardine for fish sauce production.

The liquefaction and displacement of highly saturated sand under water pressure oscillation

In order to investigate the characteristics of water wave induced liquefaction in highly saturated sand in vertical direction, a one-dimensional model of highly saturated sand to water pressure oscillation is presented based on the two-phase continuous media theory. The development of the effective stresses and the liquefaction thickness are analyzed. It is shown that water pressure oscillating loading affects liquefaction severely and the developing rate of liquefaction increases with the decreasing of the sand strength or the increasing of the loading strength. It is shown also that there is obvious phase lag in the sand column. If the sand permeability is non-uniform, the pore pressure and the strain rise sharply at which the smallest permeability occurs. This solution may explain why the fracture occurs in the sand column in some conditions.

Liquefaction and displacement of saturated sand under vertical vibration loading

In order to investigate the influence of the vertical vibration loading on the liquefaction of saturated sand, one dimensional model for the saturated sand with a vertical vibration is presented based on the two phase continuous media theory. The development of the liquefaction and the liquefaction region are analyzed. It is shown that the vertical vibration loading could induce liquefaction. The rate of the liquefaction increases with the increase of the initial limit strain or initial porosity or amplitude and frequency of loading, and increases with the decrease of the permeability or initial modulus. It is shown also that there is a phase lag in the sand column. When the sand permeability distribution is non-uniform, the pore pressure and the strain will rise sharply where the permeability is the smallest, and fracture might be induced. With the development of liquefaction, the strength of the soil foundation becomes smaller and smaller. In the limiting case, landslides or debris flows could occur.

The Combination of Rice Malt and Amyloglucosidase for the Production of Sugar Syrup from Cassava Flour

Hydrolysis of cassava flour by the combination of rice-malt extract (RME) and amyloglucosidase (AMG) on yield and type of sugars were investigated. RME was prepared by malting paddy rice for 10 days at 28°C and diastatic power determined. Effect of rice-malt enzyme concentration on rate of liquefaction and AMG concentration on rate of saccharification were studied. The combined effect of RME and AMG on yield of sugars was investigated. Simultaneous consideration of temperature, pH and time was studied using response surface methodology. Types of sugars present in syrups were identified and quantified by HPLC. Results indicated that the RME had a diastatic power of 91.46-degree Lintner. The highest RME concentration that could liquefy 10% w/v of cassava flour was 8% w/v within an hour. The combination of 8% w/v of RME with 300- units/ml AMG or 10% w/v of RME with 200-units/ml AMG resulted in the highest yield of sugars. Simultaneous consideration of temperature, pH and time indicated that the highest yield of sugars occurred at 60°C, pH 4.5 in 4.5 hours of liquefaction and saccharification. HPLC analysis on sugar syrup produced by RME alone, identified glucose, maltose and other sugars; but the combination of RME and AMG produced glucose and maltose only. In conclusion the combination of rice-malt extract with Amyloglucosidase under the specified conditions of temperature, pH and time could increase yields of sugars to DE 80 from cassava flour. (Af. J. of Science and Technology: 2002 3(1): 11-18)

Digestion of a milk-fat emulsion

In the literature there is little research on the anaerobic digestibility of lipids. In this study the anaerobic biodegradability of lipids in the form of a milk-fat emulsion was evaluated using a closed circuit, expanded granular sludge bed (EGSB) reactor. The result showed that 70% of the lipids were adsorbed on to the granular sludge within approximately one day and thereafter the remaining lipids were slowly converted to methane gas. After 26 days only 22% of the milk-fat COD was converted to methane. The biodegradation was due to the loss of colloidal COD. The adsorbed COD was for the most part not biodegraded. The poor biodegradation of milk-fat could be attributed to the limiting rate of liquefaction, as evidenced by the low hydrolysis constant, k h, of 0.01 day −1. In order to prepare the milk-fat emulsion an anionic surfactant, sodium dodecylbenzenesulfonate, was used. Anionic surfactants are reported as compounds toxic to methanogenic bacteria. A toxicity test was carried out to choose a subtoxic surfactant concentration in order to prepare an emulsion that after dilution would not present inhibition.

Effect of mixing on enzymatic liquefaction of sago starch

The effect of mixing as a function of agitation speed and impeller diameter on the rate and degree of enzymatic liquefaction of sago starch was carried out using a stirred tank reactor with a single Rushton turbine impeller. The performance of the reactor as a mixing device was first examined using different concentrations of carboxymethylcellulose, which exhibited pseudoplastic behaviour similar to that of the solution during the sago starch liquefaction process. A correlation between mixing time ( t m ) and Reynolds number (Re) in the form of t m = bRe c is presented; the constants for the correlation depended on viscosity of the fluid. For the two ratios of impeller diameter ( D i ) to tank diameter ( D t ) used, 0.407 and 0.542, agitation speed gave significant influence on both overall rate and degree of liquefaction of sago starch. Mixing time ( t m ) was independent of impeller diameter used, and correlated well with the overall rate of liquefaction ( P) (calculated as the reducing sugar produced divided by time of liquefaction) and expressed as P = 1.95 t m −0.362.

Kinetic model development for single-stage coal coprocessing with petroleum waste

Coal coprocessing with waste petroleum materials achieves the dual purpose of upgrading both the coal and the waste materials economically. The kinetics of coal coprocessing with petroleum waste has been studied experimentally and modeled mathematically. A combined parallel and series reaction scheme was assumed for the coal liquefaction. Experiments were carried out in a tubing bomb microreactor at temperatures of 375 to 425°C, at reaction times of 15–120 min, with 10% coal loading and with 1250 psig pressure. Coal conversions as high as 98% were obtained during coprocessing. More than 70% conversion to oil is achieved at high temperatures and grease loadings. The effect of temperature and grease loading on coal liquefaction were also studied. A rigorous parameter estimation technique was employed to determine the parameters involved in the model. The model predictions are good for experimental conditions other than those used to determine the model parameters. Higher conversion and higher rate of liquefaction obtained during coprocessing were explained from the obtained kinetic rate parameter values.

Studies of acute pancreatitis with retroperitoneal necrosis: “The suet syndrome”. Improvements in patient survival

Over a career, 76 patients with massive retroperitoneal necrosis associated with acute pancreatitis were initially treated conservatively. Seventy-one subsequently required operative debridement, between 18 days and 13 months after onset of the disease, including 3 who were explored within the first 2 weeks. In the absence of secondary infection, clinical evidence of toxemia was variable, sometimes relatively limited and occasionally minimal, even in association with large amounts of necrotic tissue. In almost all patients the necrotic tissue consisted chiefly of adipose tissue in the retroperitoneum, including the intramesenteric spaces. In 2 patients, the parapancreatic and retroperitoneal mass appeared to consist predominantly of old, partially liquefied blood clots. Liquefaction of necrotic tissue occasionally proceeded extremely slowly over a period of months. In no patient, up to a maximal lapse of 13 months, was liquefaction complete at the time of exploration. Of the 76 consecutive patients with massive retroperitoneal necrosis, managed by delayed and often frequent debridement, 2 patients (2.6%) died. An occasional patient had significant necrosis of the pancreas, per se; approximately 90% did not. Necrotic retroperitoneal adipose tissue or associated hematoma may prove quite toxic, but was sometimes well tolerated over a prolonged period. The advent of secondary infection leads rapidly to toxemia and, possibly, to an increased rate of liquefaction.

Influence of donor amount in the hydrogen-transfer liquefaction of Australian brown coal

Effects of tetrahydrofluoranthene (4HFL) concentration on the product composition in the liquefaction of an Australian brown coal at 450 °C were studied, using a coal-solvent weight ratio of 1:3 under low nitrogen pressure to optimize the conditions. Pure 4HFL solvent liquefied the coal very rapidly, a longer reaction time markedly increasing the yield of gaseous product as well as the total yield of oil and asphaltenes. Although a reduction in the 4HFL content of the solvent reduced the rates of liquefaction for both gas and liquid products, 4HFL contents of 75 and 50 mol% provided more favourable product compositions (high yield, > 80% of oil plus asphaltenes and low yields of preasphaltenes and gaseous products). In liquefaction of the deashed coal with 75 % 4HFL, the product composition was further improved by using a shorter reaction time. Several roles of donors in the liquefaction process are proposed to explain the product composition and rate of liquefaction.