Cryogenic Method Research Articles

Recent advancements in hydrogen storage - Comparative review on methods, operating conditions and challenges

Green hydrogen, proposed as a sustainable alternative for conventional fuels, has gained utmost importance due to its reduced carbon footprint and potential application in maintaining balance between energy generation and demand. Utilization of hydrogen-based systems are challenged by cost effective storage methods. Bio-hydrogen storage technologies using cryogenic and adsorptive methods are discussed in this review paper, along with their operating conditions and storage capacities. An analysis of operational challenges and recent advancements in hydrogen storage techniques is presented. With a storage pressure of 70 MP, cryogenic hydrogen is almost twice as dense as compressed hydrogen. Technical challenges such as material cost and explosion risk can be addressed by hydrogen adsorption on activated carbon active sites. Maximum hydrogen storage capacity are reported by activated carbon obtained from Chitosan (6.77 wt%), Bamboo (6.6 wt%) and African palm shell (6.5 wt%) at 77 K and 4–20 Mpa. Further, nanotechnology approaches are presented in detail for increasing hydrogen storage capacity in pristine Si and Mg. The future perspectives in terms of technological, and economic aspects are discussed.

Formability enhancement and deformation mechanism of 2195 Al Li alloy sheet in cryogenic forming

Cryogenic medium pressure forming is very suitable for producing thin-walled, complex-shaped aluminum alloy components. In order to evaluate the feasibility of the new forming process, an innovative cryogenic hydro-bulging method and corresponding device was developed to determine the cryogenic formability under biaxial tensile stress. An analysis of cryogenic biaxial stress-strain relations was conducted to quantify the strain hardening behavior. The deformation mechanisms at cryogenic temperature were investigated by analyzing microstructures. The limiting expansion ratio of the 2195 AlLi alloy solution-treated sheet at −196 °C increases to 38.7%, 95.5% more than that at 20 °C. The acquired cryogenic biaxial stress-strain curve demonstrates significantly enhanced strain hardening ability at −196 °C. The strain and thickness distribution are more uniform at −196 °C due to the increased cryogenic strain hardening ability. The enhanced cryogenic plasticity and strain hardening ability is caused by the formation of uniform high-density dislocations and dislocation cells at −196 °C, which is conducive to uniform dislocation slip and localized deformation suppression. It demonstrates cryogenic medium pressure forming is very suitable for manufacturing thin-walled complex-shaped aluminum alloy components due to its enhanced cryogenic biaxial formability.

Preparation of ZnCo2O4 porous nano-flower-like materials by one-step cryogenic hydrothermal method and study on their capacitive and photocatalytic properties

Preparation of ZnCo2O4 porous nano-flower-like materials by one-step cryogenic hydrothermal method and study on their capacitive and photocatalytic properties

Development of a cryogenic passive-scattering-type near-field optical microscopy system.

Passive scattering-type, scanning near-field optical microscopy (s-SNOM) has been employed to study localized, long-wavelength infrared (LWIR) surface waves without external illumination. Here, we develop a cryogenic passive s-SNOM instrument in a vacuum chamber with 4K liquid-helium cooling. Notably, the extremely low-temperature environment inside the chamber enables the realization of passive near-field detection with low background thermal noise. The technique mainly utilizes a highly sensitive LWIR confocal optical system and a tuning fork-based atomic force microscope, and the near-field detection was performed at a wavelength of 10.2 ± 0.9 µm. In this paper, we discuss the cryogenic s-SNOM implementation in detail and report the investigation of thermally excited surface electromagnetic fields on a self-heated NiCr wire deposited on SiO2 at a temperature of 5K. The origin of the surface electromagnetic fields was established to be the thermally excited fluctuating charges of the conduction electrons. The cryogenic s-SNOM method presented herein shows significant promise for application in a variety of spheres, including hot-carrier dissipation in ballistic conductors.

A Production and Fractionation Protocol for Polyvinyl Chloride Microplastics

Concerns about the presence of microplastics in the environment has increased in recent years, prompting more attention from scientists. Thorough exposure studies using artificially produced microplastics containing additives are required to assess their potentially hazardous effects. Therefore, an efficient microplastic production and fractionation protocol was established using a cryogenic grinding and wet-sieving approach. The developed cryogenic grinding method was able to produce (20-40 g/h) polyvinyl chloride (PVC) microplastics having a volume-weighted mean particle size of 391 µm and a span of 2.12. Performing a second grinding cycle on the same particles resulted in microplastics which were smaller (volume-weighted mean size = 219 μm) and had a narrower particle size distribution (span = 1.59). In addition, the microplastics were also fractionated into different particle size ranges using a vibrating wet-sieving tower. The latter technique allowed separating 10 g of PVC microplastics into seven different fractions using six sieves (Ø 200 mm) for 30 min while shaking. By using the developed method, PVC microplastics could easily be made and fractionated into desired particle-size ranges. The proposed protocol could also be adjusted to produce and fractionate microplastics of other plastics.

PEO composite solid polymer electrolytes with the synergistic effect of cryogenic engineering and trace BP nanosheets for nearly room temperature and 4 V class all-solid-state lithium batteries

A novel PEO-based SPE with a synergistic effect of black phosphorus (BP) nanosheets and a cryogenic method, which can combine the advantages of the fast Li+ pathways of BP nanosheets and the low PEO crystallization of cryogenic method.

BIST-Supported Cryogenic Write Trimming With In-MRAM Computing Case Study

In the processor-memory separated von- Neumann computation paradigm, the “memory-wall” effect becomes critical due to large access latency and tremendous amount of data movement. In this work, we pursue cryogenic temperature based memory design and focus on spin-transfer-torque magnetoresistive random access memory (STT-MRAM) at 77-Kelvin (achieved with low-cost liquid nitrogen). Cryogenic compact model and its related cryogenic bit-cell are investigated, based on 77 K experiment data of magnetic tunnel junction (MTJ) and CMOS transistor. Compared with the simulated room temperature results, 70% reduction of sensing latency can be obtained at 0.7 V supply voltage, whereas writing latency and yield performance are significantly degraded. In order to overcome the above drawbacks, a novel joint trimming system is proposed including a build-in- self-test (BIST) block and a string of multi-stage level shifters (LS). A case study is executed with in-MRAM computing (IMC). Results show that cryogenic IMC with write trimming provides performance improvements of 33% on average, and concurrently reduces memory energy consumption by 70% on average. The proposed 77 K cryogenic design method can be further applied to other energy constrained applications.

Research on the use of agricultural waste to manufacture highly hygroscopic materials for agricultural applications

Material based on hydrogel from rice-straw with high absorption capacity and slow water release was prepared by cryogenic method, using citric acid as cross-linker and without creating waste stream to the environment. The structure and properties of the material were characterized by SEM, XRD, FTIR and TGA method. The results showed that the largest water absorbency of the material reached 30.67g/g, 4.48 times higher than the original rice-straw. The material was able to slowly release water in 6 days at room temperature and return water absorption of 3.97 g/g when reusing the material. In addition, the material is biodegradable and biocompatible. With the obtained results and simple, inexpensive, environmentally friendly method, this is a material that can be industrially produced and widely used in green agriculture.

TECHNOLOGIES OF CRYOGENIC STORAGE OF ELECTRICITY FROM RENEWABLE SOURCES

The peculiarities of storing electricity produced by traditional systems of its production and using renewable energy sources are considered, the state of the problem is discussed. Examples of industrial application of electricity storage systems using compressed and liquefied air are given. Liquid air storage systems have been shown to be the most efficient. A scheme for the accumulation of electricity and its production with the use of turbo-expander power generator units with the use of liquefied air is proposed. Taking into account the situation that has developed in Ukraine in connection with the spread of the COVID-19 virus, a scheme for obtaining liquid medical oxygen by the cryogenic method on low-tonnage transportable equipment is proposed. Bibl. 10, Fig. 2.

Effects of dehydrofreezing conditions on tomato lycopene and kinetics of lycopene change in dehydrofrozen tomatoes during storage

AbstractIn the study, the change in lycopene content of tomatoes, which were frozen either fresh or after being partially dehydrated with different methods (convective, osmotic, and vacuum dehydration) during the 6‐month storage at −20°C was investigated. In the freezing process, tomatoes were frozen at 2 m/s air flow velocity by convective method and at different freezing temperatures (−30, −35, −40°C) and cryogenic method up to the thermal center temperature of the samples reaches to −20°C. It was determined that the reaction representing the lycopene change during the storage process occurred in accordance with the first‐order kinetic model. The reaction rate constants (k) determined for the lycopene change during the storage process of the tomatoes frozen by the convective method were found to be affected by freezing conditions and the results revealed that the k value decreased with reducing temperature. It was found that the half‐life time of the lycopene change reaction during the storage period increased as the freezing temperature decreased in the tomatoes frozen by the convective method. In general, it was seen that in terms of lycopene preservation of tomatoes, freezing of tomatoes with cryogenic method after being dehydrated by vacuum and osmotic treatment gave better results The lycopene loss at the end of the 6‐month storage was determined to be 46.4% in the tomatoes frozen by the cryogenic method after being dehydrated by the osmotic treatment, whereas it was 64% in the samples that were freshly frozen at −30°C.Practical applicationsDehydrofreezing is a food freezing method in which the foods are partially dehydrated and then frozen. Traditional freezing methods cause serious damage to the vegetal products. Reducing the water that will be frozen in the dehydrofreezing process allows to form ice crystals without damaging the cellular structure of vegetables. Because of the reduction of tissue damage, sensitive nutrients are less affected by process conditions. As a result; for food producers, dehydrofreezing technology seems to be more advantageous as it means less processing time, more weight product for unit volume and high quality products. In conclusion, according to the results, freezing the tomatoes by dehydrofreezing method gives better results to protect the tomato lycopene during storage.

Influence of Cryogenic Behaviour on Copper Electrode for Non-Conventional EDM

In the last few decades, non-traditional machining has increased the efficiency of the machining process. One of the most prevalent non-traditional methods of milling is through the use of an EDM process. Traditional machining methods can't easily machine materials with a complicated profile or hardness that EDM can handle. The industrial sector makes extensive use of EDM. Cryogenically treated copper electrodes and regular copper electrodes were used to conduct an experiment on an EN24 material using varied input parameters, such as electrode rotation, gap voltage, and discharge current. Electric discharge machining was used in a study. The Taguchi method is used to design experiments. Three input parameters were employed in an orthogonal L16 array to find an optimal value for each of the three components. OC (overcut), TWR (Tool wear rate), and Ra (surface roughness) are the three output variables. The S/N ratio can be used to determine the best values and relative relevance of each of these factors using a statistical analysis of variance (ANOVA) table. Additionally, the overcut, tool wear rate, and surface roughness of traditional and non-traditional EDM are examined. For the deep cryogenic and non-traditional machining method, conventional and non-traditional electric discharge machining methods were found to have optimal or dominant factors for the TWR and Ra.

Experimental comparisons of different cryogenic fracturing methods on coals

Hydraulic fracturing using water-based fracturing fluids is widely used in coalbed methane (CBM) reservoir development. However, the stimulation efficiency of conventional hydraulic fracturing in CBM reservoir is low. Liquid nitrogen (LN2) cryogenic fracturing is one possible method to improve the stimulation efficiency. To test the feasibility of the LN2 cryogenic fracturing, laboratory fracturing tests were conducted to investigate the performances of different LN2 cryogenic fracturing methods in this paper. The breakdown pressure and fracture morphology of water fracturing, LN2 direct fracturing, LN2 freeze fracturing, LN2 freeze-thaw fracturing and LN2 compound fracturing were compared. And the mechanisms of different cryogenic fracturing techniques are revealed. The results demonstrate that thermal damage caused by LN2 freezing is the main reason for the complicated fracture pattern in cryogenic fracturing. LN2 freeze-thaw fracturing has the lowest breakdown pressure and can create the most complex fractures among these cryogenic fracturing methods due to the huge thermal damage. LN2 freeze fracturing has the highest breakdown pressure. Because the thermal damage cracks and natural fractures in frozen rock are in freezing shrinkage, which activation are difficult. LN2 compound fracturing is the most potential technologies, which can produce more complex fracture networks than water fracturing and LN2 fracturing.

An analysis on the impacts of cryogenic freezing on raspberry quality

Counter-season supply of horticultural products is of increasing demand. Consumers are demanding annual supply of raspberries, which has historically been challenging due to their seasonal summer supply and characteristically high metabolism resulting in a short shelf life and limited period of availability. However, the development of freezing technologies for increasing the length of storage of raspberries offers an opportunity for continual supply of premium quality raspberries. We investigated berry quality after freezing whole fresh raspberries, comparing conventional freezing methods with a modern cryogenic freezing method over a period of six months. Significant increases in total soluble solids, titratable acidity, hue and chroma were found when raspberries were frozen compared to fresh raspberries. No overall difference in berry quality was observed between freezing methods for any parameter assessed. When assessed at time intervals, total soluble solids, pH, titratable acidity, chroma and hue were consistent between freezing methods for all durations of time frozen. These findings provide decision support for producers and distributors pursuing a novel counter season supply chain.

Cryogenic milling-based keratin microparticle production from Anatolian goat fibers and their structural, chemical and thermal properties

Fibers procured from Anatolian goat ( Capra aegagrus hircus) furs were converted into keratin microparticles by the cryogenic milling method. Single-stage mechanical milling with a 2.5 h optimal grinding time was sufficient enough to generate the desired high-quality microparticles. No chemical solvents were utilized during the production process of keratin microparticles. Structural, chemical and thermal properties of keratin microparticles were assessed using particle size analyzer, stereo microscope, Brunauer–Emmett–Teller™ surface analyzer, field emission scanning electron microscope, X-ray diffractometer, attenuated total reflection Fourier transform infrared spectroscopy, thermogravimetric analyzer and differential scanning calorimetry methods. According to the characterization results, microparticles with amorphous structure in micro size could be produced without any agglomeration during the milling process. Goat farming is usually for dairy products and their fibers have very limited use in the textile industry because of their flat structure. Therefore, the conversion of goat fibers into another product that can be used in other industrial areas is expected to contribute significantly to a sustainable economy.

Removal of contamination in helium for precise SF6‐based Δ36S measurements

Quantifications of quadruple sulfur isotopic compositions (δ34 S, Δ33 S, and Δ36 S) of sulfur-bearing compounds in nature are valuable for providing new insights into the Earth's evolution such as the crust-mantle cycle, oxygenation of atmosphere and oceans, and the origin and evolution of early life. SF6 -based isotope ratio mass spectrometry is the most widely used method of quantification, but Δ36 S measurements at high precision and accuracy have always been technically difficult due to the low abundance of 36 S (~0.01%). In this paper, we identify a major source of isobaric interferences (i.e., contamination in helium carrier gas in the gas chromatography purification step) and propose a simple strategy to solve this problem. An SF6 fluorination and purification system was built. Laboratory SF6 reference gas and international Ag2 S standard (IAEA-S1) were used as reference materials to test our method. Contamination from helium carrier gas (99.999%) was purified by a simple two-step cryogenic method to allow for accurate and precise measurements of Δ36 S using the SF6 -based isotope ratio mass spectrometry method. Without proper purification of helium carrier gas, large errors in Δ36 S measurements were found. Measured Δ36 S values of SF6 with trace contamination from helium were >10‰ higher than expected values. Using a newly developed purification strategy, the difference in Δ36 S values of SF6 before and after passing through the gas chromatography is less than instrumental errors (<0.2‰). Our improved method yielded an overall Δ36 S precision for IAEA-S1 of 0.12‰ (n = 6). This precision is comparable to that found by other laboratories around the world. Our simple two-step cryogenic method significantly improved the accuracy and precision of Δ36 S measurements and is therefore recommended for future determination of quadruple sulfur isotopic compositions in natural samples.

A novel cryogenic rolling method for commercially pure titanium sheets featuring high strength and ductility

Commercially pure titanium (CP Ti) has a low yield strength (YS); consequently, its utilization is limited to industrial applications that do not require high load-bearing capabilities. Cryogenic deformation has been regarded as an effective method for strengthening CP Ti. However, this method increases production costs and degrades ductility, thereby hindering the commercialization of cryogenic deformation for industrial production. In this study, we devised a two-temperature rolling method for CP Ti by combining room-temperature rolling (RTR) and cryogenic-temperature rolling (CTR), which can induce significant material strengthening while reducing the number of rolling passes required at cryogenic temperature. The RTR and CTR sequence substantially affected the strengthening degree. Employing CTR for only a part of the total area reduction (AR) induced considerable strengthening comparable to that obtained by employing it for the entire AR. Furthermore, the two-temperature rolling process did not appreciably degrade the ductility, despite inducing considerable strengthening, leading to an excellent strength–ductility combination. We identified microstructural factors for the high strength and ductility in the processed CP Ti. The devised rolling method is highly cost-effective, as it can reduce the proportion of cryogenic-temperature treatment in the whole rolling process; thus, this methodology will contribute considerably to the commercialization of CTR for industrial applications.

Differences in stable isotope compositions δ2H and δ18O in water samples extracted from strawberries in Da Lat and Moc Chau

Strawberry samples were collected from Dalat and Mocchau regions and extracted by a cryogenic vacuum method. Stable isotope compositions δ2H và δ18O in the extracted water were then analysed by a Liquid Water Isotope Analyzer (LWIA-24D). The evaluated results showed that, at the statistical significance level α=0.05, the δ2H and δ18O values obtained at Mocchau and Dalat samples are clearly different (p&lt;0.001). In detail, the mean value of δ2H for strawberries grown in Mocchau (-42.83‰) was more enriched than that in Dalat (-53.99‰). In contrast, the value of δ18O for strawberries grown in Mocchau (-9.25‰) is more depleted than in Dalat (-5.67‰). In addition, the δ2H and δ18O values in each region are strongly correlated and can be distinguished based on the position of the correlation line relative to the global meteoric water line.

Grand Challenges in Membrane Process for Gas Separation

Membrane technology is the most promising technology in the post-combustion capture technology compared to absorption, adsorption and cryogenic distillation methods. It is an advanced new technology for recovery of carbon dioxide. It has several advantages when compared to other methods due to its’ simple process, low cost, lower footprint, sustainable environment and energy saving method. The challenge is the fabrication method of the polymeric membrane, and it depends on the particular utilisation of the membrane. Different morphologies of the membrane structure can be produced using different methods.

The Resource Potential and Development Prospect of Helium in Changqing Gas Field

Helium, a rare gas widely applied in high-tech fields, is a significant strategic resource in China. The foreign-trade dependence ratio of helium in China is 95%. The work reviewed the applications and market analysis of helium and reservoir modeling and distribution of helium in Changqing Gas Field as well as the helium extraction techniques from natural gases. According to the analysis of the component test and the dynamic monitoring of exploited gas wells and gas-gathering stations, the average helium content in Changqing Gas Field was 0.028%. Helium was rich in the northwest of Changqing Gas Field, but poor in the central and eastern regions. The helium volume contents in Qingyang Gas Field, Huanglong Gas Field, and the central, western, and southern regions of Sulige Gas Field have reached the industrial development standard. PetroChina performed the economic-feasibility evaluation and production-factor matching research on helium development and selected Changqing Gas Field as the demonstration for development. A large helium plant was established in Changqing Gas Field using the cryogenic method with/without membrane separation for helium extraction. Then, a helium development scheme was formulated and implemented to build the industry chain of helium in China. Changqing Gas Field is rich in helium resources. Developing helium has entered a strategic period with the technological advancement in extracting helium from natural gases and the increased prosperity of the international helium market. There are broad prospects and great benefits to exploiting helium resources in Changqing.

Non-Destructive Removal of Dental Implant by Using the Cryogenic Method.

Background and Objectives: The gold standard for a successful prosthetic approach is the osseointegration of an implant. However, this integration can be a problem in cases where the implant needs to be removed. Removing the implant with minimal damage to the surrounding tissues is important. Osteocytes cannot survive below −2 °C, but epithelial cells, fibroblasts, and other surrounding tissue cells can. Remodeling can be triggered by cryotherapy at temperatures that specifically affect osteocyte necrosis. In this study, we aimed to develop a method for reversing the osseointegration mechanism and for protecting the surrounding tissues by bone remodeling induced by CO2 cryotherapy. Materials and Methods: In this study, eight 2.8 mm diameter, one-piece mini implants were used in New Zealand rabbit tibias. Two control and six implants were tested in this study. After 2 months of osseointegration, a reverse torque force method was used to remove all osseointegrated implants at 5, 10, 20, and 30 Ncm. The osseointegration of the implants was proven by periotest measurements. Changes in bone tissue were examined in histological sections stained with toluidine blue after rabbit sacrifice. The number of lacunae with osteocyte, empty lacunae, and lacunae greater than 5 µm and the osteon number in a 10,000 µm2 area were calculated. Cryotherapy was applied to the test implants for 1 min, 2 min, and 5 min. Three implants were subjected to cryotherapy at −40 °C, and the other implants were subjected to cryotherapy at −80 °C. Results: Empty lacunae, filled osteocytes, lacunae >5 µm, and the osteon count around the implant applied at −40 °C were not significantly different from the control implants. The application of −40 °C for 1 min was found to cause minimal damage to the bone cells. The implants, which were applied for 1 min and 2 min, were successfully explanted on the 2nd day with the 5 Ncm reverse torque method. Test implants, which were applied cold for 5 min, were explanted on day 1. Tissue damage was detected in all test groups at −80 °C. Conclusions: The method of removing implants with cryotherapy was found to be successful in −40 °C freeze–thaw cycles applied three times for 1 min. To prove implant removal with cryotherapy, more implant trials should be conducted.