Volumetric Expansion Ratio Research Articles

Experimental Characterization of Commercial Scroll Expander for Micro-Scale Solar ORC Application: Part 1

In order to reduce greenhouse gas emissions and achieve global decarbonisation, it is essential to find sustainable and renewable alternatives for electricity production. In this context, the development of distributed generation systems, with the use of thermodynamic and photovoltaic solar energy, wind energy and smart grids, is fundamental. ORC power plants are the most appropriate systems for low-grade thermal energy recovery and power conversion, combining solar energy with electricity production. The application of a micro-scale ORC plant, coupled with Parabolic Trough Collectors as a thermal source, can satisfy domestic user demand in terms of electrical and thermal power. In order to develop a micro-scale ORC plant, a commercial hermetic scroll compressor was tested as an expander with HFC-245fa working fluid. The tests required the construction of an experimental bench with monitoring and control sensors. The aim of this study is the description of the scroll performances to evaluate the application and develop optimization strategies. The maximum isentropic effectiveness is reached for an expansion ratio close to the volumetric expansion ratio of the scroll, and machine isentropic effectiveness presents small variations in a wide range of working conditions. The filling factor is always higher than one, due to leakage in the mechanical seals of the scroll or other inefficiencies. This study demonstrates that using a commercial scroll compressor as an expander within an ORC system represents a valid option for such applications, but it is necessary to improve the mechanical seals of the machine and utilize a dedicated control strategy to obtain the maximum isentropic effectiveness.

High-Efficiency Antibacterial Hemostatic AgNP@Zeolite/Chitin/Bamboo Composite Sponge for Wound Healing without Heat Injury.

Chitin is a popular hemostatic material, but there are still many deficiencies in its ability to effectively stop bleeding, prevent infection, and fit wounds. Herein, AgNP@zeolite/chitin/bamboo (AgZ-CB) composite sponges with shape recovery are prepared to minimize blood loss, kill bacteria, and promote wound healing. Notably, the bamboo powder is used for the first time to remarkably enhance the softness of the composite sponge (volumetric expansion ratio >5). The fabricated AgZ-CB sponge exhibits an excellent killing effect (≈100% bactericidal rate) against both Escherichia coli and Staphylococcus aureus and activates internal and external coagulation pathways to accelerate hemostasis without causing thermal damage (≈5 °C temperature difference). Moreover, the AgZ-CB sponge shows less blood loss (26mg) and a shorter time to hemostasis (42 s) than the commercial polyvinyl formal sponge (84mg and 76 s) in the full-thickness liver injury model. The in vivo wound healing and biodegradation experiment indicate that AgZ-CB with excellent biocompatibility can close wounds efficiently. Overall, the AgZ-CB sponge has great potential in combating a series of obstacles in wound healing.

Green demolition technology of reinforced concrete slab: Application of soundless chemical demolition agents and its evaluation system

AbstractThe annual global building demolition is burdensome due to the rapid development of cities. The pollution associated with building demolition severely endangers the urban environment. Soundless chemical demolition agents (SCDAs) can effectively avoid environmental hazards in the demolition of concrete buildings. However, related literature on optimal hole layout design is still vacant. The demolition of reinforced concrete slabs was therefore explored in this paper. In total, 18 slab specimens were tested. Results showed that the slab specimens were demolished into several blocks due to sufficient development of cracks. Following this, a set of complete evaluation system was proposed. First, the volumetric expansion ratio of SCDAs was provided as a new evaluation index. Based on this evaluation index, the influences of critical parameters and the influence mechanism of reinforcements were investigated. Second, a novel multi‐parameter hole layout computational model was established. With this model, an optimal hole layout scheme could be obtained. Finally, the application prospect of SCDAs was discussed. This work can open up a new vision for the demolition industry.

Numerical evaluation on the effect of rebar corrosion on long-term structural behavior of underground RC culverts

This study aims to investigate the effects of steel corrosion on long-term structural behavior of underground RC culvert based on the multiscale computational model. Finite element (FE) analysis is conducted on past experiments of simply supported RC beams in which corrosion is electrically introduced into reinforcing bars to validate whether the multiscale computational model reasonably evaluates the structural performance of corroded RC members. By utilizing the validated FE model, numerical simulations of actual underground RC culvert are carried out on various corrosion scenarios. The results of comprehensive analyses show that both corrosion rate and volumetric expansion ratio of corrosion products have a significant effect on deterioration process and structural damage, and that the long-term structural behavior of RC culvert is greatly affected not only by corrosion degree, but by rebar corrosion condition depending on surrounding environments. Therefore, it can be recognized that attention should be paid to environmental conditions around RC structure as well as corrosion amounts for lifetime prediction and long-term performance evaluation, integrating knowledges of material behavior and structural response.

Incorporation of Mycelium (Pleurotus eryngii) in Pea Protein Based Low Moisture Meat Analogue: Effect on Its Physicochemical, Rehydration and Structural Properties.

The protein content of a plant-based ingredient is generally lower than its animal food counterpart, and research into novel alternative protein is required that can provide similar protein content, texture and appearance as meat. This work investigates a mycelium-based low moisture meat analogue (LMMA) approach, by incorporating 0 to 40% w/w mycelium (MY) into pea protein isolate (PPI) via extrusion using a twin-screw extruder at 140 °C die temperature, 40 rpm screw speed, and 10 rpm feeder speed (0.53–0.54 kg/h). Physicochemical, rehydration, and structural properties of LMMA were assessed. The MY incorporation led to a significant change in color attributes due to Maillard reaction during extrusion. Water solubility index and water absorption capacity increased significantly with MY addition, owing to its porous structure. Oil absorption capacity increased due to increased hydrophobic interactions post-extrusion. Protein solubility decreased initially (upto 20% w/w MY), and increased afterwards, while the water holding capacity (WHC) and volumetric expansion ratio (VER) of LMMA enhanced with MY addition upto 30% w/w. Conversely, WHC and VER decreased for 40% w/w which was verified with the microstructure and FTIR analysis. Overall, MY (30% w/w) in PPI produced a fibrous and porous LMMA, showing future potential with an increasingly plant-based product market and decreasing carbon footprint of food production activities.

A Preliminary Design and Modeling Analysis of Two-Phase Volumetric Expanders for a Novel Reversible Organic Rankine-Based Cycle for Carnot Battery Technology

Carnot battery technology appears to be a promising solution to increase the development of power generation and offers a good solution for high-capacity, day-to-day energy storage. This technology may utilize the waste heat and store the electricity to recover it later. This article reports the preliminary analysis of a specially designed Carnot battery configuration employing a novel reversible Rankine-based thermodynamic cycle (RRTC). In this case, one volumetric expander is not only installed to generate power from a heat engine, but also to recover power during heat pump operating mode. The preliminary design and modeling results were obtained based on calculations taken from working fluid thermal properties of propane with some specific boundary conditions (i.e., secondary fluid hot temperature of 348.15 K, cooling temperature of 228.15 K, and waste heat temperature of 338.15 K). The results show that isentropic efficiency, pressure, and volumetric expansion ratio from both heat engine and heat pump operating modes are important parameters that must be taken into account when designing the two-phase expander for RRTC. The obtained results show that a designed two-phase volumetric expander in RRTC features a pressure ratio of 2.55 ± 1.15 and a volumetric ratio of 0.21 ± 0.105, and the Carnot battery may achieve the performance of 0.50–0.98.

Effects of the combination of compression and impregnation with phenolic resin on the dimensional stability in the multiscale wood structure of Chinese fir

Chinese fir wood was pretreated by phenol–formaldehyde (PF) resin and followed by the compression along the radial direction at the compression ratio of 10%, 20% and 30%, respectively. The microscopic images of the control and modified wood at different humidity were then collected to evaluate the dimensional stability of wood cellular structures. The interactions between the cell wall and resin were also observed by SEM and Raman spectroscopy to reveal the fixation effects of resin on the compressed wood at cell-level. Results indicated that the number of wood cells filled with PF resin increased significantly with the increase of impregnation pressure and processing time, which contributed to an obvious decrease in the linear and volumetric expansion ratio of wood at high humidity, in particular at the RH of 90%. The filling of PF resin in the wood cell lumen and the open pits on the tracheid walls not only inhibited the entry of water molecules but also had a chemical interaction with cell-wall, which could significantly reduce the set-recovery of the compressed wood. The radial expansion ratio of wood at a compression ratio of 30% has been reduced by about 65% at the RH of 90% after PF resin impregnation.

Corrosion of Strained Plain Rebar in Chloride-Contaminated Mortar and Novel Approach to Estimate the Corrosion Amount from Rust Characterization

Some of the steel bars used in reinforced concrete construction experience plastic strain due to various operations at construction sites. The present work concentrates on the corrosion behavior of such prestrained reinforced bars (rebars) embedded in chloride-contaminated cement mortar and exposed to laboratory conditions (temperature of 27°C±2°C and relative humidity of 60%) for 18 months. The corrosion behavior of these rebars was examined in terms of the electrochemical parameters [open circuit potential (OCP) and polarization resistance (RP)], effective volumetric expansion ratio, and the thickness of the rust at the metal–mortar interface. Cyclic change in the OCP and RP of the bars with time has been observed due to the formation of corrosion products at the interface. The preinduced plastic strains affected both the polarization resistance and the corrosion-induced mass loss of the rebar. The strained rebars showed higher corrosion susceptibility and corrosion amount than the unstrained rebars due to the changes in the surface condition and microstructure on account of high plastic deformation. The mass of the iron lost to form rust at the interface has been estimated using a novel volumetric expansion ratio model by taking the individual contribution of corrosion products at the interface. Correlation between the degree of straining and the corrosion-induced cracks at the end of 18 months of exposure has also been established.

Quantitative CT-based image registration metrics provide different ventilation and lung motion patterns in prone and supine positions in healthy subjects

BackgroundPrevious studies suggested that the prone position (PP) improves oxygenation and reduces mortality among patients with acute respiratory distress syndrome (ARDS). However, the mechanism of this clinical benefit of PP is not completely understood. The aim of the present study was to quantitatively compare regional characteristics of lung functions in the PP with those in the supine position (SP) using inspiratory and expiratory computed tomography (CT) scans.MethodsNinety subjects with normal pulmonary function and inspiration and expiration CT images were included in the study. Thirty-four subjects were scanned in PP, and 56 subjects were scanned in SP. Non-rigid image registration-based inspiratory-expiratory image matching assessment was used for regional lung function analysis. Tissue fractions (TF) were computed based on the CT density and compared on a lobar basis. Three registration-derived functional variables, relative regional air volume change (RRAVC), volumetric expansion ratio (J), and three-dimensional relative regional displacement (s*) were used to evaluate regional ventilation and deformation characteristics.ResultsJ was greater in PP than in SP in the right middle lobe (P = 0 .025), and RRAVC was increased in the upper and right middle lobes (P < 0.001). The ratio of the TF on inspiratory and expiratory scans, J, and RRAVC at the upper lobes to those at the middle and lower lobes and that ratio at the upper and middle lobes to those at the lower lobes of were all near unity in PP, and significantly higher than those in SP (0.98–1.06 vs 0.61–0.94, P < 0.001).ConclusionWe visually and quantitatively observed that PP not only induced more uniform contributions of regional lung ventilation along the ventral-dorsal axis but also minimized the lobar differences of lung functions in comparison with SP. This may help in the clinician’s search for an understanding of the benefits of the application of PP to the patients with ARDS or other gravitationally dependent pathologic lung diseases.Trial registrationRetrospectively registered.

Prediction of corrosion products of iron at a low‐level radioactive waste disposal facility in Japan

AbstractEstimation of the volumetric expansion ratio due to the corrosion of metals is an essential part of the safety assessment of low‐level radioactive waste disposal facilities in Japan, because such volumetric expansion can disrupt the barrier function of these facilities. In the present study, the corrosion products of iron were predicted from potential–pH diagrams and the results of a synthesis test, and the volumetric expansion ratios of the corrosion products were evaluated. Under a basic set of conditions expected at a disposal facility over a storage period of a thousand to tens of thousands of years, Fe3O4, Fe2O3, and FeOOH were predicted as the major stable corrosion products of iron. The maximum volumetric expansion ratio determined from the true density of these products was 2.9, and the maximum volumetric expansion ratio, assuming the generation of voids in the corrosion products, was 3.7, which is the Pilling–Bedworth ratio of Fe(OH)2. The volumetric expansion ratio may increase in the presence of carbonate ions in a long‐term environment with a reduced pH.

Flame acceleration and blast wave of H2–O2–N2–Ar mixtures in unconfined areas

In the present study, the flame acceleration and blast wave of H2-air and H2–O2–N2–Ar mixtures in nearly unconfined conditions were investigated conducting laboratory-scale and large-scale experiments. In particular, the effect of the volumetric expansion ratio on the flame acceleration examined, because Darrieus-Landau instability is essentially caused by a volumetric expansion of burned gas at flame front. Results demonstrated that the critical Péclet number Pec for the onset of flame acceleration decreased with the decrease in the equivalence ratio and the increase in the expansion ratio diluted with Ar. The dimensionless burning velocity increased as the flame radius became larger. The acceleration exponent for H2-air and H2–O2–N2–Ar mixtures was evaluated. The saturation of the exponent corresponding to the fractal dimension for only very lean H2-air flame is observed, notwithstanding the value for other mixtures still existed in the transition regime. The blast wave intensity of H2-air and H2–O2–N2–Ar explosion discussed by the acoustic theory. From the analysis, it is clear the blast wave intensity depends on the expansion ratio, laminar burning velocity and flame acceleration.

The Method of the Working Fluid Selection for Organic Rankine Cycle (ORC) Systems Employing Volumetric Expanders

The working fluid selection is one of the most important issues faced when designing Organic Rankine Cycle (ORC) systems. The choice of working fluid is dictated by different criteria. The most important of them are safety of use, impact on the environment, and physical and chemical parameters. The type of ORC system in which the working fluid is to be used and the type of expander applied in this system is also affecting the working fluid selection. Nowadays, volumetric expanders are increasingly used in ORC systems. In the case of volumetric expanders, in addition to the aforementioned working fluid selection criteria, additional parameters are considered during the selecting of the working fluid, such as the range of operating pressures and geometric dimensions (determining the volume of working chambers) affecting the achieved power and efficiency of the expander. This article presents a method of selecting a working medium for ORC systems using volumetric expanders. This method is based on the dimensionless rating parameters applied for the comparative analysis of different working fluids. Dimensionless parameters were defined for selected thermal properties of the working fluids, namely thermal capacity, mean temperature of evaporation, mean temperature of condensation, pressure and volumetric expansion ratio, volumetric expandability, as well as the heat of preheating, vaporization, superheating, cooling, and liquefaction. Moreover, isentropic expansion work was considered as the rating parameter. In this article, in addition to the working fluid selection method, computational examples related to the selection of the working fluid for the ORC system fed by a heat source featuring specified temperatures are presented. The results of calculations of rating parameters and their comparison gave an outlook on the selection of appropriate working fluids.

Determination of expandability clay from San José de Cúcuta metropolitan area, by adding different percentages of sewage sludge

This article shows the research carried out on clay from the San José de Cúcuta metropolitan area, Colombia, to which was added several percentages of a wastewater sludge, which is called as a technological nutrient. The objective of the study is to find out with what percentage of technological nutrient the capacity of expansion of the granules is maximized. The methodology that was followed consists of four phases; preparation of raw materials; pelletizing of raw materials in granules of 5 to 10 millimeters; application of heat treatment in a rotary kiln at the pilot plant level; and application of descriptive statistics for analysis of results. It was determined that the mixture with a 20% of technological nutrient, produces the highest volumetric expansion ratio, with 1.56 times its initial size, while, when adding 30% of the nutrient the same expansion occurs when adding an 10% nutrient, which is 1.07 times the initial size of the particle.

Identification of corrosion products and 3D distribution in reinforced concrete using X-ray micro computed tomography

Abstract The main purpose of this study is to non-destructively monitor the formation and development of corrosion products in reinforced mortar with the help of X-ray micro computed tomography (X-ray µCT). A new method based on the relationship between the linear attenuation coefficient and CT number as well as greyscale value is built to identify different type of corrosion products. Based on this method, two categories of corrosion products including iron oxides and iron hydroxides are identified in this research. Additionally, the corrosion mechanism and the interaction between different types of corrosion products are discussed according to the characteristics of corrosion evolution. Furthermore, the volumetric expansion ratio of corrosion products is quantified (from 2.71 to 3.97). This method provides a new angle to investigate the formation and development of reaction products, which contributes to further understand the corrosion process in reinforced concrete.

Performance of an Organic Rankine Cycle with two expanders at off-design operation

The objective of this work was to simulate the behavior of an Organic Rankine Cycle (ORC) system with two expanders in series at off-design working conditions. The influence of both the intermediate pressure and the volumetric expansion ratio of the expanders on the off-design performance of the ORC was studied and the irreversibilities of the components were analyzed. The performance of the ORC with two expanders for two different designs was also discussed.The thermal efficiency reached using two expanders was higher than the obtained using only one. However, this increase conveyed an increase in the complexity of the design and control of the expanders. As an additional conclusion, it was found that the influence of the intermediate pressure is higher than that of the volume expansion ratio of each expander.The irreversibility of the first expander was mainly due to leaks. However, the performance of the second expander was particularly affected by the difference between the discharged pressure and the condensation pressure. The off-design analysis allowed the definition of a methodology to achieve the desired power with the maximum thermal efficiency, and the identification of the best actuation for the part load operation.

Influence of superheat and expansion ratio on performance of organic Rankine cycle-based combined heat and power (CHP) system

The purpose of this study is to investigate the performance characteristics of subcritical organic Rankine cycle (ORC) based combined heat and power (CHP) system according to a variation of major operating parameters and to confirm the possibility of system performance improvement. The CHP system is designed to provide output using a 200 °C heat source, including at least 2 kW of electric power and 25 kW of thermal power with 60 °C of hot water supply. Besides examining a basic ORC-based CHP system, variations of system configurations combined with heat exchangers for additional heat recovery have been considered. The effects of changes in superheat and expander volumetric expansion ratio on system performance were evaluated based on thermodynamic analysis and optimization results for each system and working fluids.Eight candidate working fluids selected for superior thermophysical properties and environmental impacts were classified into three groups according to the magnitude of latent heat, and four types of CHP system configuration with additional heat exchangers were considered. Group A working fluids with the largest latent heat include cyclopentane, isopentane, n-pentane, and diethyl ether, while medium latent heat group B working fluids include R-1233zd and R-245fa. The smallest latent heat group C working fluids include HFE-7000 and HFE-7100. The operating conditions and performance of the CHP systems were calculated considering the fixed heat source temperature (200 °C), the superheat amount, the volumetric expansion ratio and the isentropic efficiency of the expander for parametric analyses.Studies have shown that the group A working fluid systems are superior in performance to other fluid systems. According to the parametric analyses, the increase in superheat has a positive effect regardless of the configuration in the system using the group B working fluids. Other working fluid systems can also be expected to enhance the performance by increasing the degree of superheat in system configurations where an internal heat exchanger (IHE) and a post-heater (PH) are employed together. Increasing the volumetric expansion ratio and the isentropic efficiency of the expander improves the performance of all working fluid systems. Especially, it has been concluded that the addition of the post-heater is essential if the CHP performance is to be improved by increasing the volumetric expansion ratio and the isentropic efficiency of the expander.

Multiple Expansion ORC for Small Scale – Low Temperature Heat Recovery

ORCs are widely recognized as one of the most suitable solution for energy recovery, if the temperature of the heat source is of about 200°C, or lower. In case of heat sources of about 100 kW or smaller, the more common solutions prescribe a simple cycle and a single stage expander, in order to reduce complexity and costs. Scroll expanders, derived from scroll compressors, are expected to be available at very low unit costs. The drawbacks of this kind of solutions, originally designed for automotive, or HVAC applications, are mainly two: the low fixed volumetric expansion ratio and the small volumetric flow rate, that are not always well-suited for the requirements of power production. In this paper, different ORCs with multiple expansions are evaluated with the aim of achieving a better exploitation of small scale-low temperature waste heat sources. The comparison takes in consideration different possible solutions for the multiple expansions, with internally recuperated and not-recuperated cycles, whilst the data describing the actual behaviour of compressors derived scroll expanders have been previously obtained by a test rig, set up at the University of Trieste, using R245fa as working fluid.

Heat-Generating Expandable Foamed Gel Used for Water Plugging in Low-Temperature Oil Reservoirs

Polymers are often used for chemical water plugging. When the reservoir temperature is lower than 50 °C, the reaction between polymers and cross-linking agents is very slow, which extensively prolongs the gelation time and even leads to unsuccessful gelation. To overcome such problems, a foamed-gel system that is capable of spontaneous in situ heat generation was developed. The optimal system was identified through the orthogonal test using the gel strength, gelation time, and gel volume as indexes. The test shows that, when the ambient temperature is fixed at 30 °C and the pH value is 6.8, the system performs well. Under such circumstances, the gelation time is 40 h, the gel strength reaches the G grade, and the volumetric expansion ratio at 10 MPa exceeds 130%. Nuclear-magnetic-resonance-based T2 spectra indicate that the foamed gel injected into the rock can effectively plug large pores and, therefore, offset the heterogeneity. It is also found that the foamed gel has great capacity for volumetric expa...

Airflow patterns in a 3D model of the human acinus

Based on the recent photographs of microstructures of anacinus a novel 3D computational model for airflow and particle transport and deposition was developed. To model the entireacinar region simultaneously, an approach was proposed to reduce the computational space. The airflow was solved using numerical simulations for the cases of expanding and contracting the asinus wall. The volume change of the lung was imposed based on the normal breathing condition with 15% volumetric expansion ratio. Since the entire acinar region was modeled, realistic pressure type boundary conditions were used and the use of earlier unrealistic boundary conditions was avoided. The simulation results showed that the flow patterns in an acinus with moving walls were significantly different from those for the rigid wall case. Furthermore, due to the asymmetric configuration, the flow patterns were not quite symmetric. It was shown that the ratio of alveolar flow to ductal flow rate controlled the dominant flow regime in each generation. Ratios below 0.005led to recirculation regime where flow separation occurred, while values above this threshold led to flows with radial streamlines. In summary, while the flow in the primary generations was characterized by the formation of recirculation regions in the alveoli, the terminal generations were characterized by radial streamlines which move towards the alveolar wall. Both flow regimes had substantial effects on particle deposition in the acinus.

Hard anodizing of AA2099-T8 aluminum‑lithium‑copper alloy: Influence of electric cycle, electrolytic bath composition and temperature

AA2099-T8 samples have been hard anodized in a traditional sulphuric bath with the aim of studying the influence of i) electrolyte temperature, ii) Al3+ concentration and iii) different electric cycles in direct current, multi-step direct current and pulsed current (both completely anodic cycles and with cathodic “off” pulses). Anodic oxide thickness, volumetric expansion ratio (Vox/VAl), mean hardness (HV0.05), faradic efficiency and defective state have been analyzed. As temperature decreases, the oxide hardness increases but defectiveness steeply worsens; similarly a middle compromise of Al3+ concentration ensures the best performances. Regimes of high current, from one side, and of low current and current transient, from the other side, strongly affect oxide defective state introducing different types of flaws; an appropriate balance is crucial for a performing non-defected oxide. High current induces the occurrence of parasitic reactions which produce rough and defected Al/ox interface. Low current and current transient induce diffused cracking and detachments of coating fragments which decrease corrosion resistance as shown by potentiodynamic polarization tests. Li-based intermetallics play a crucial role in the last mentioned flaw-creation phenomena since they produce inhomogeneities in electric field distribution and contribute to create unstable oxide structures.