Optimum Volume Ratio Research Articles

Experimental study of an improved air-source heat pump system with a novel three-cylinder two-stage variable volume ratio rotary compressor

Traditional air source heat pumps (ASHPs) only can work above about −20 °C to −25 °C, and have limitations in terms of performance. This paper proposes a novel three-cylinder two-stage variable volume ratio (TSVVR) rotary compressor to improve the performance of the ASHP. Utilizing the variation characteristics of the compressor optimal volume ratio under the different temperatures, the compressor volume can be switched for better performance. Experiments are conducted on the improved ASHP with the TSVVR rotary compressor and the two traditional ASHPs with the single-stage and two-stage compressor using the simulation of the residential building in the environmental laboratory. The results show that the TSVVR system operates in a stable manner with the COP of 1.52 W/W at −30 °C, and achieves a higher COP than the traditional ASHPs. The optimal volume ratio decreases with the decrease of the evaporation temperature. The TSVVR system works in the three-cylinder mode at low temperature and directly expands the heating capacity and compression efficiency because of the increase of the low-pressure volume and suction volume. When the water temperature varies between 40 °C and the maximum possible temperature, the COP of the TSVVR system is 18.4−22.3% higher and 6.6–7.3% higher than the single-stage and two-stage systems, respectively; when the indoor temperature varies between 12.5 °C and 18 °C, the COP of the TSVVR system is around 18.4−23.4% and 5.2–8.8% higher than the single-stage and two-stage systems, respectively. The two-cylinder mode of the TSVVR system has a larger volume ratio than the single-stage and two-stage ASHPs and is closer to the optimal volume ratio, which is more suitable for the high temperature and low load conditions. In the three-cylinder mode, the TSVVR system has a smaller volume ratio, and the compression efficiency and system refrigerant flow rate increase, when the evaporation temperature is low. Two modes ensure that the TSVVR system always work in the efficient states, especially in the low temperature environments.

Optimal volume ratio of two-stage vapour compression system using zeotropic refrigerant

Refrigerant mixtures are commonly regarded as a potential substitute in heat pumps. Two-stage compression is widely applied for improving the performance of heat pumps. The suction volume ratio is a critical design parameter for two-stage heat pumps. In this work, the optimal volume ratio of R32/R1234ze(E) mixture and 26 refrigerants named by ASHRAE Standard 34-2013 are estimated. The obtained result indicates that, for R32/R1234ze(E) mixtures, the optimal volume ratio first decreases and then increases as the R32 component increases, and the optimal volume ratio of flash tank system is lower than the intermediate heat exchanger system owing to component shifting in the flash tank. For estimated 26 refrigerants, the optimal volume ratio of the majority of zeotropic refrigerants is smaller than pure refrigerants and azeotropic refrigerants. In addition, a modified arithmetic mean temperature method is proposed to predict the optimal intermediate refrigerant states.

Rapid synthesis and characterization of ambient pressure dried monolithic silica aerogels in ethanol/water co-solvent system

In this paper, using methyltrimethoxysilane (MTMS) as precursor, silica aerogels (SA) with excellent performance were synthesized within 10 h via APD without further surface modification and solvent exchange. The investigation was concentrated on three primary factors, including base catalyst, surfactant, and co-solvent system. The results indicated that NH3·H2O concentration and the volume ratio of NH3·H2O to MTMS were of great importance to the formation of particles, clusters, and pores. It was also obtained that the surfactant of CTAB influences the pore structure as well as thermostability of prepared aerogels significantly. Furthermore, an optimum volume ratio of EtOH/H2O in co-solvent system not only reduced the volume shrinkage but also enabled a good hydrophobicity of prepared SAs.Base on above, by adjusting the preparation parameters, the obtained SAs can exhibit the low density of 0.0968 g/cm3, low thermal conductivity of 0.037 W m−1 K−1, contact angle as high as 144.7° and thermostability reaching up to 528.1 °C. Meanwhile, some specific performance of SAs, such as hydrophobicity, could be tailored, which will improve its applicability.

Two-phase micro-electromembrane extraction across free liquid membrane for determination of acidic drugs in complex samples

A dynamic two-phase micro-electromembrane extraction (μ-EME) using electrically induced transfer of charged analytes directly into free liquid membrane (FLM) is proposed as a novel technique for improving enrichment capabilities of μ-EME. The presented set-up employs aqueous sample as donor solution and water immiscible organic solvent (1-octanol) as FLM, which form the two-phase μ-EME system for efficient extraction of model acidic drugs (ibuprofen, ketoprofen, naproxen and diclofenac) from standard solutions, human urine, human serum and wastewater samples. The FLM eliminates migration of matrix components from the complex samples and simultaneously it acts as an acceptor solution for selective trapping and enrichment of the analyte ions. Electrodes are immersed directly into the sample and the FLM and replenishment of analyte ions at the sample/FLM phase interface is accomplished by stirring the sample solution using a conventional laboratory stirrer. At optimized two-phase μ-EME conditions (100 V, 15 min, 1000 rpm) and optimized volume ratio of sample to FLM (480:16 μL), extraction recoveries of 60–97% and enrichment factors up to 29.1 were achieved. Determination of the acidic drugs in resulting FLMs was achieved by capillary electrophoresis with ultraviolet detection with good linearity (r2 ≥ 0.9998) and low limits of detection (4–20 ng/mL).

Solvent-assisted heat treatment for enhanced chemical stability and mechanical strength of meta-aramid nanofibers

Meta-aramid exhibits excellent chemical stability and mechanical strength owing to its rigid crystal structure. However, the crystal structure is destroyed when meta-aramid nanofibers (mANFs) are fabricated by electrospinning, which results in nanofibers with poor performance characteristics. Here, we present a facile solvent-assisted heat treatment for the efficient crystallization of mANFs. The optimal volume ratio of the co-solvent solution was determined to be 6:5:100 (DMAc:ethylene glycol:water), and the optimal crystallization temperature 120 °C. The crystallinity of the mANFs obtained under these optimized conditions (mANF-6-120) is higher than the crystallinity of mANFs heat-treated at 300 °C (mANF-HT). As a result, mANF-6-120 exhibits superior chemical stability and mechanical strength compared to mANF-HT. After immersion in DMAc for 48 h, the weight of mANF-6-120 is reduced to 28% of its original weight, whereas the relative remaining weight of mANF-HT is less than 8%. The value of Young’s modulus of mANF-6-120 is 1.7 times higher than that of mANF-HT. The crystallization process developed in this study requires less energy and is less expensive than the conventional high-temperature heat treatment process. The meta-aramid nanofiber mat obtained using the proposed process shows great promise for application to water purification and the treatment of polluted air.

The establishment of a chyle testing method based on n-hexane extraction system

Objective To set up a chyle (n-hexane) testing method based on n-hexane extraction system. Methods The hydrothorax specimen which was positive in chyle testing was selected and the feasibility was evaluated by replace Diethyl ether with n-hexane. The optimal extraction volume ratio for the new chyle testing was confirmed and sultan Ⅲ dye process was improved. Then, the new chyle testing method and its standard operation process was established.A total of 120 specimens with triglyceride(TG)in different levels were collected and divided into three groups with 40 specimens for each group (group A. TG≤1.7 mmol/L; B. 5.6<TG<12.8 mmol/L; C. TG≥12.8 mmol/L). Then, 50 body fluid specimens were collected and used to confirm the above test results. A total of 134 real body fluid specimens were used to assessment the clinical using by review and calculating the clinical coincidence rate. Results N-hexane can replace Diethyl ether in the Chyle test. The extraction volume ratio of 1 ml sample plus 400 μl N-hexane is the best one and the sultan Ⅲ tube dying method is better than former direct smear. Compared with the old Chyle test using Diethyl ether, the new Chyle test using N-hexane is in good consistency with the Kappa value 0.95. The clinical coincidence rate of the above Chyle test reaches 94.8%(127/134) after the verification of 134 specimens. Conclusions A new N-hexane test is established successfully. It was convenient to operate with high security and little contamination and thus has a wide clinical application value.(Chin J Lab Med, 2018, 41: 527-530) Key words: Chyle; Hexanes; Ethyl ethers; Clinical laboratory techniques

Biosynthesis of (R)-2-hydroxy-3-phenylpropionic acid using whole recombinant Escherichia coli cells in an aqueous/n-octane biphasic system.

(R)-2-hydroxy-3-phenylpropionic acid (PLA) is an ideal antimicrobial compound with broad-spectrum activity against a wide range of Gram-positive bacteria, some Gram-negative bacteria, and fungi. We studied the bioconversion of phenylpyruvate (PPA) to PLA using whole recombinant Escherichia coli cells in a series of buffer/organic solvent systems. Octane was found to be the best organic solvent. The optimum volume ratio of the water phase to the n-octane phase, conversion temperature, substrate concentration, and cell concentration were 6:4, 40 °C, 12.5 g/L, and 30 g/L wet cells, respectively. Under the optimized conditions, the average PLA productivity in the aqueous/ n-octane system was 30.69% higher than that in the aqueous system, and 32.31 g/L PLA was obtained with the use of a stirred reactor (2-L scale). Taken together, our findings indicated that PLA biosynthesis was more efficient in an aqueous/n-octane biphasic system than in a monophasic aqueous system. The proposed biphasic system is an effective strategy for enhancing PLA yield and the biosynthesis of its analogues.

Energy-neutral sustainable nutrient recovery incorporated with the wastewater purification process in an enlarged microbial nutrient recovery cell

Recovery of nutrient resources from the wastewater is now an inevitable strategy to maintain the supply of both nutrient and water for our huge population. While the intensive energy consumption in conventional nutrient recovery technologies still remained as the bottleneck towards the sustainable nutrient recycle. This study proposed an enlarged microbial nutrient recovery cell (EMNRC) which was powered by the energy contained in wastewater and achieved multi-cycle nutrient recovery incorporated with in situ wastewater treatment. With the optimal recovery solution of 3 g/L NaCl and the optimal volume ratio of wastewater to recovery solution of 10:1, >89% of phosphorus and >62% of ammonium nitrogen were recovered into struvite. An extremely low water input ratio of <1% was required to obtain the recovered fertilizer and the purified water. It was proved the EMNRC system was a promising technology which could utilize the chemical energy contained in wastewater itself and energy-neutrally recover nutrient during the continuous wastewater purification process.

Fabrication and characterization of a solution-processed electron transport layer for organic-inorganic hybrid halide perovskite photovoltaics

In this study, suspended zinc oxide nanoparticles were used as the electron transport layer in trans-perovskite solar cells. The perovskite film was prepared by a liquid two-step method, and the crystallinity, surface morphology, and optical and photoelectric properties of the perovskite films were then investigated. The results showed that the crystallinity and film compactness of the perovskite could be controlled by the stoichiometric quantity and the perovskite formation rate. Moreover, the film morphology was affected by the annealing temperature, duration, and the amount of toluene solvent, which could be leveraged to enhance the efficiency of the device due to the charge trapping defect. The optimal annealing temperature and duration were 80 °C and 10 min, and the optimal volume ratio of isopropyl alcohol to toluene was 9:1. The highest performing perovskite solar cells in this study exhibited an energy conversion efficiency of 15.78%, a short-circuit current of 20.80 mA/cm2, an open circuit voltage of 1.10 V, and a fill factor of 0.69.

Effect of MWCNT Filler on Properties and Flux of Chitosan/ PEG based Nanocomposites Membranes

Biopolymer are expected to be environmentally compatible and to have great potential application as membranes material. The chitosan-poly (ethylene glycol)/PEG based composite membranes was successfully synthesized via inversed phase method. The effect of multiwalled carbon nanotubes (MWCNT) as nanofiller on properties and performances of composite membranes were intensively evaluated. The membrane was prepared by mixing of chitosan and PEG solutions at the same composition ratio while MWCNT amount in the mixture was varied. The synthesized membrane was characterized by means of FTIR spectroscopy, scanning electron microscopy (SEM), contact angle, and tensile strength measurement. The performance of composite membrane on filtration was evaluated in term of flux (permeability) and rejection (rejection) tests. The results showed that the optimum volume ratio of composite membrane solution was found at 30:10:7.5 for chitosan/ PEG/ MWCNT, respectively, as indicated by the largest flux. Insertion of MWCNT nanofiller notably enhanced hydrophilicity, porosity, and mechanical properties of composites membranes that are confirmed by contact angle, SEM images and elongation forces value, respectively. The MWCNT nanofiller remarkably increased both of flux and rejection of composite membranes up to 60 Lm2h-1 and 96%, respectively. The remarkable enhancement of composite membrane performance is attributed to the effective interaction of MWCNT with polymeric matrix.

Fatty acid profile from immobilised Chlorella vulgaris cells in different matrices

ABSTRACTThe immobilisation of Chlorella vulgaris 211/11B entrapped in combinations of natural matrices to simplify the harvesting process was demonstrated in this study. Three combinations of matrices composed of calcium alginate (CA) and sodium alginate (SA), sodium carboxymethyl cellulose (CMC) and SA, and mixed matrices (SA, CA, and CMC) were investigated. The number of cells grown for each immobilised matrix to microalgae volume ratios (0.2:1–1:1) were explored and compared with using SA solely as a control. The optimum volume ratios obtained were 1:1 for SA, 0.3:1 for CA and SA, 1:1 for CMC and SA, and 0.3:1 for mixed matrices. The immobilised microalgae of mixed matrices exhibited the highest number of cells with 1.72 × 109 cells/mL at day 10 and 30.43% of oil extraction yield followed by CA and SA (24.29%), CMC and SA (13.00%), and SA (6.71%). Combining SA, CA, and CMC had formed a suitable structure which improved the growth of C. vulgaris and increased the lipid production compared to the immobilisation using single matrix. Besides, the fatty acids profile of the oil extracted indicates a high potential for biodiesel production.

Analysis of volume ratio of castor/soybean oil mixture on minimum quantity lubrication grinding performance and microstructure evaluation by fractal dimension

As a non-edible, degradable, and environment-friendly crop product, castor oil can be used as lubricating oil in material processing. However, its high viscosity results in poor flowability, thereby limiting its industrial applications. Although experiments have revealed the excellent lubrication performance of castor/soybean oil mixture, the volume ratio of castor oil and soybean oil can significantly influence their minimum quantity lubrication (MQL) grinding performance. In the current study, seven castor/soybean oil mixtures under different volume ratios ranging between 1:0.5 and 1:4 were prepared for MQL grinding of Ni-based alloy. The mixed oils were compared with pure castor oil (1:0) in terms of viscosity and tribological behaviors. The grinding experiment involved the evaluation of specific grinding force, surface roughness, surface microtopography, and grinding debris, conluding that the preferred castor/soybean volume ratios were found to be 1:0.5, 1:1, 1:1.5, and 1:2. The surface microtopographies of selected workpieces were analyzed further in terms of their fractal dimension and scale coefficient, finding that the maximum fractal dimension (D=1.31) and minimum scale coefficient (G=0.30) are achieved when the volume ratio is 1:2. Hence, the optimal volume ratio is determined.

Thermoelectric generator based on composites obtained by sintering of detonation nanodiamonds

A model of a thermoelectric generator is proposed, in which composite materials obtained by sintering diamond nanoparticles are used as the main component. To increase the useful conversion of heat into electric current, it is proposed to use the effect of electron drag by ballistic phonons. To reduce the ineffective heat spread, it is proposed to use the effect of thermal resistance of the boundaries between the graphite-like and diamond-like phases of the composite.An experimental confirmation of the existence of an optimal volume ratio between graphite-like and diamond-like phases of the composite is predicted and obtained.The highest achieved value of thermoelectric coefficient in the actual structure is 80 µV K−1 (which means 20 times increase compared to that of composites not of the optimal structure), with a thermal conductivity of 50 W m−1 K−1. These results were obtained with constant electrical conductivity. The combined influence of these two effects in case of the ideal composite structure should result in an increase of the thermoelectric efficiency parameter by three orders of magnitude.

Selection of anti-solvent and optimization of dropping volume for the preparation of large area sub-module perovskite solar cells

Anti-solvents play a critical role on the preparation of perovskite active layers for photovoltaic applications. This work explores the treatment of various anti-solvents for adjusting the crystallinity and morphology of perovskite active layer. It is found that the anti-solvent with a low dielectric constant and dipole moment is the most suitable one for the preparation of perovskite layer. It is also noted that the optimal volume ratio of the perovskite precursor to toluene as an anti-solvent is 1:3. Using toluene as the anti-solvent, the perovskite solar cells (p-i-n type) are fabricated with a single cell and a sub-module within an active area of 0.10cm2 and 11.25cm2, respectively. Such display exhibits impressive power conversion efficiencies (PCE) of 13.12% and 11.60% with negligible J-V hysteresis, respectively, under the illumination of 100mW/cm2 (AM1.5G).

Improvement of CH3NH3PbI3 thin film using the additive 1,8-diiodooctane for planar heterojunction perovskite cells

The thin-film quality is critical for obtaining high-performance perovskite solar cells (PSCs). The additive 1,8-diiodooctane (DIO) was used to control the morphology and structure of CH3NH3PbI3 perovskite thin films, and planar heterojunction (PHJ) PSCs with an architecture of ITO/PEDOT: PSS/CH3NH3PbI3/PCBM/Al was fabricated. It was found that the DIO played an important role on CH3NH3PbI3 thin-film quality and the performance of PHJ-PSCs. With the optimal volume ratio of 2%, the compact and uniform high-quality CH3NH3PbI3 thin films with enhanced crystallinity and less roughness were achieved, resulting in the great improvement of power conversion efficiency (PCE) from about 4.5% to over 9.0%. The research results indicate that the additive DIO is a simple and effective method to produce high-quality perovskite thin film and accordingly develop high-performance PHJ-PSCs.

Theoretical Study of the BaTiO₃ Powder's Volume Ratio's Influence on the Output of Composite Piezoelectric Nanogenerator.

The combination of the piezoelectric materials and polymer is an effective way to make the piezoelectric nanogenerator (PENG) possess both the polymer’s good flexibility and ferroelectric material’s high piezoelectric coefficient. The volume ratio of ferroelectric material in the composite is an important factor that determines the PENG’s output performance. In this paper, the BaTiO3/polydimethylsiloxane (PDMS) composite PENG was demonstrated as having an optimal volume ratio (46%) at which the PENG can output its highest voltage, and this phenomenon can be ascribed to the trade-off between the composite PENG’s top electrode charge and its capacitance. These results are of practical importance for the composite PENG’s performance optimization.

Optimization of a soft degumming process of crude rapeseed oil—Changes in its antioxidant capacity

A modified soft degumming process of crude rapeseed oil for maximizing phospholipid removal and minimizing losses of antioxidants was proposed and optimized by response surface methodology. The effects of water volume, degumming time, and concentration ratio of sodium dodecyl sulfate to disodium ethylenediaminetetraacetate on the concentration of phospholipids and phenolics and antioxidant capacity of oils were evaluated. The soft degumming process removed phospholipids from the crude oil (94.9–98.7%) more effectively than industrial acid degumming (95.3%). Moreover, rapeseed oils revealed high phenolic content (20.0–22.1mg sinapic acid (SA)/100g) and antioxidant capacity, as determined by ferric-reducing antioxidant power (FRAP=301–328μmol Trolox equivalent (TE)/100g), 2,2-diphenyl-1-picrylhydrazyl (DPPH=528–739μmol TE/100g), and 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS=1300–1505μmol TE/100g) methods.The predicted optimum water volume (11.5mL), time (19.7min), and concentration ratio of sodium dodecyl sulfate to disodium ethylenediaminetetraacetate (=1) resulted in total phospholipids=67mg/kg, phenolics=20.8mg SA/100g, FRAP=313μmol TE/100g, DPPH=617μmol TE/100g, and ABTS=1346μmol TE/100g.Replacement of industrial acid degumming by the proposed soft degumming can improve the stability of rapeseed oil with potent antioxidant capacity.

Establishment of an analytical method for accurate purity evaluations of acylcarnitines by using quantitative 1H NMR spectroscopy

Recently, it has become possible to examine metabolism abnormalities by detecting increases in specific acylcarnitines in blood tests of newborn babies using tandem mass spectrometer. However, acylcarnitine standard solutions with metrological traceability to the International System of Units (SI) for accurate calibration of tandem mass spectrometer are not yet available worldwide. In this study, we examined a quantitative 1H NMR procedure for obtaining accurate and SI-traceable purity evaluations of acylcarnitines having different numbers of carbon atoms as each raw material for their standard solutions. In particular, the solvent composition and measurement temperature were optimized to reduce the influence of water signal overlapping on analyte signals. It was found that, when the signal of that 1H which directly bound to the asymmetric carbon of the acylcarnitine is the target signal, it was possible to reduce overlapping of the water signal on the target signal by using deuterium oxide as a solvent. On the other hand, in the case of an acylcarnitine that was poorly soluble in deuterium oxide, it was possible to reduce overlapping of the water signal on the target signal by adding an appropriate amount of deuterium oxide to methanol-d 4 in which the acylcarnitine had high solubility. At this time, the optimum mixing volume ratio of methanol-d 4/deuterium would be 80:20. The overlapping of the water signal could be also reduced when the measurement temperature was 15 °C to 40 °C. When the measurement temperature was an around room temperature (in this study, 25 °C), fine shimming could be performed easily. Therefore, the optimum temperature would be 25 °C, because fine shimming was essential to quantify any signal area accurately. Finally, this study confirmed that accurate values with SI traceability could be obtained at about 1 % or less expanded uncertainty for five kinds of acylcarnitines.

Characterization of Nylon 6 Nano Fiber/E-Glass Fiber Reinforced Epoxy Composites

In the paper thermoplastic polymer Nylon-6 is generated in the form of Nanofibers by using an electro spinning method, and concentration of a solution is 4% as a constant then, by varying the process parameters such as flow rate (0.8 ml/hr, 1ml/hr and 1.2 ml/hr) of the solution. The results indicated Nanofibers with 4% concentration and 1 ml/hr produced optimum fibers due to continuous fiber formation. Composites Plates are fabricated by using a Hand lay-up method with different volume fraction (0.5, 1, 2 % v/v) of Nanofibers ratio. Then, the optimum Nanofibers volume ratio (2 % v/v) is reinforced with E-glass fibers and epoxy resin as a matrix. In order to find Nanofibers effect, Mechanical properties like (Tensile, Flexural and Impact) is performed and evaluated.

Early and simultaneous detection ofNosema bombycis(Microsporidia: Nosematidae), nucleopolyhedrovirus (Baculoviridae), and densovirus (Parvoviridae) by multiplex real-time polymerase chain reaction inBombyx mori(Lepidoptera: Bombycidae)

AbstractAn effective multiplex real-time polymerase chain reaction (PCR) assay for the simultaneous detection of three major pathogens,Nosema bombycisNägeli (Microsporidia: Nosematidae),Bombyx morinucleopolyhedrovirus (Baculoviridae: genusAlphabaculovirus) (NPV), andBombyx moridensovirus (Parvoviridae: genusIteravirus) (DNV), in silkworms (Bombyx mori(Linnaeus); Lepidoptera: Bombycidae) was developed in this study. Polymerase chain reaction and real-time PCR tests and basic local alignment search tool searches revealed that the primers and probes used in this study had high specificities for their target species. The ability of each primer/probe set to detect pure pathogen DNA was determined using a plasmid dilution panel, in which under optimal conditions the multiplex real-time PCR assay showed high efficiency in the detection of three mixed target plasmids with a detection limit of 8.5×103copies forN. bombycisandBombyx moriNPV (BmNPV) and 8.5×104copies forBombyx moriDNV (BmDNV). When the ability to detect these three pathogens was examined in artificially inoculated silkworms, our method presented a number of advantages over traditional microscopy, including specificity, sensitivity, and high-throughput capabilities. Under the optimal volume ratio for the three primer/probe sets (3:2:2=N. bombycis:BmNPV:BmDNV), the multiplex real-time PCR assay showed early detection of BmNPV and BmDNV by day 1 post inoculation using DNA templates of the three pathogens in various combinations from individually infected silkworms; the early detection ofN. bombyciswas possible by day 3 post inoculation using the DNA isolated from the midgut ofN. bombycis-infected silkworms.