Basic Principles for Substantiation of Working Pair Choice

2021 ◽  
pp. 25-42
Keyword(s):  
Operating Temperature ◽  
Low Cost ◽  
Molecular Size ◽  
Porous Matrix ◽  
Coefficient Of Performance ◽  
Basic Principles ◽  
Temperature Range ◽  
Low Viscosity ◽  
Wide Availability ◽  
Heat Of Evaporation

The chapter is devoted to basic principles for substantiation of working pair choice. Principles for substantiation for selection of adsorbate and adsorbent are considered. The main requirements to adsorbate are formulated as follows: low cost, easy of obtaining, small molecular size to facilitate the adsorption effect; high latent heat of evaporation and small volume in liquid state; high thermal conductivity; low viscosity, thermal stability with adsorbent in the operating temperature range; chemical stability in the working temperature range; non-toxicity for animals and human, non-aggressiveness and incombustibility; low pressure saturation (slightly above atmospheric pressure) at normal operating temperature; the absence of environmental problems. Water is shown to conform to these requirements. The crucial requirements to adsorbent are the ability to adsorb large amounts of adsorbate when cooled to environment temperature and give a high cooling effect; high values of maximal adsorption; desorption of the major portion of adsorbate (ideally all) when heated by an accessible source of heat; low heat capacity; good heat conductivity, short cycle time; no deterioration and loss of adsorption capacity over time or use; non-toxicity, non-aggressiveness; chemical physical compatibility with the selected adsorbate; low cost and wide availability. Properties of various types of adsorbents were compared. Composites ‘salt inside porous matrix' are shown to be promising media for heat storage and transformation. Characteristics of thermodynamic cycles of heat conversion were analysed. The ways to improve the coefficient of performance were analysed and shown to be affected by a proper choice of an adsorbent.

scholarly journals Thermodynamic Performance of a Double-Effect Absorption Refrigeration Cycle Based on a Ternary Working Pair: Lithium Bromide + Ionic Liquids + Water

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4200 ◽  
Author(s):  
Yiqun Li ◽  
Na Li ◽  
Chunhuan Luo ◽  
Qingquan Su
Keyword(s):  
Least Squares Method ◽  
Operating Temperature ◽  
Double Effect ◽  
Coefficient Of Performance ◽  
Specific Enthalpy ◽  
Refrigeration Cycle ◽  
Absorption Refrigeration ◽  
Temperature Range ◽  
Thermodynamic Performance ◽  
Operating Temperature Range

For an absorption cycle, a ternary working pair LiBr–[BMIM]Cl(2.5:1)/H2O was proposed as a new working pair to replace LiBr/H2O. The thermodynamic properties including specific heat capacity, specific enthalpy, density, and viscosity were systematically measured and fitted by the least-squares method. The thermodynamic performance of a double-effect absorption refrigeration cycle based on LiBr–[BMIM]Cl(2.5:1)/H2O was investigated under different refrigeration temperatures from 5 °C to 12 °C. Results showed that the ternary working pair LiBr–[BMIM]Cl(2.5:1)/H2O had advantages in the operating temperature range and corrosivity. Compared with LiBr/H2O, the operating temperature range was 20 °C larger, and the corrosion rates of carbon steel and copper were reduced by more than 50% at 453.15 K. However, the double-effect absorption refrigeration cycle with LiBr–[BMIM]Cl(2.5:1)/H2O achieved a coefficient of performance (COPc) from 1.09 to 1.46 and an exergetic coefficient of performance (ECOPc) from 0.244 to 0.238, which were smaller than those based on LiBr/H2O due to the higher generation temperature and larger flow ratio.

scholarly journals A Person-to-Person and Person-to-Place COVID-19 Contact Tracing System Based on OGC IndoorGML

2020 ◽  
Vol 10 (1) ◽  
pp. 2 ◽  
Author(s):  
Soroush Ojagh ◽  
Sara Saeedi ◽  
Steve H. L. Liang
Keyword(s):  
Data Model ◽  
Low Cost ◽  
Large Body ◽  
Contact Tracing ◽  
Trajectory Data ◽  
Sequential Order ◽  
Human Contact ◽  
Wide Availability ◽  
Data Points ◽  
The Impact

With the wide availability of low-cost proximity sensors, a large body of research focuses on digital person-to-person contact tracing applications that use proximity sensors. In most contact tracing applications, the impact of SARS-CoV-2 spread through touching contaminated surfaces in enclosed places is overlooked. This study is focused on tracing human contact within indoor places using the open OGC IndoorGML standard. This paper proposes a graph-based data model that considers the semantics of indoor locations, time, and users’ contexts in a hierarchical structure. The functionality of the proposed data model is evaluated for a COVID-19 contact tracing application with scalable system architecture. Indoor trajectory preprocessing is enabled by spatial topology to detect and remove semantically invalid real-world trajectory points. Results show that 91.18% percent of semantically invalid indoor trajectory data points are filtered out. Moreover, indoor trajectory data analysis is innovatively empowered by semantic user contexts (e.g., disinfecting activities) extracted from user profiles. In an enhanced contact tracing scenario, considering the disinfecting activities and sequential order of visiting common places outperformed contact tracing results by filtering out unnecessary potential contacts by 44.98 percent. However, the average execution time of person-to-place contact tracing is increased by 58.3%.

scholarly journals Optimization of Mordenite Membranes Using Sucrose Precursor for Pervaporation of Water-Ethanol Mixtures

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 160
Author(s):  
Abdulaziz A. Alomair ◽  
Yousef Alqaheem
Keyword(s):  
Pyrolysis Temperature ◽  
Operating Temperature ◽  
Selective Adsorption ◽  
Sucrose Concentration ◽  
Low Cost ◽  
Water Flux ◽  
Separation Performance ◽  
Carbon Membranes ◽  
Adsorption Of Water ◽  
High Separation

Post-treated mordenite membranes were prepared using sucrose (C12H22O11) as a carbon precursor to block any pinholes and defects in the zeolite layer. The pervaporation (PV) process was used to separate ethanol from the water. The effects of the sucrose concentration and the pyrolysis temperature (650–850 °C) were investigated, and the resulting high separation performance compared to those post/pre-treated membranes was reported in the literature. In this study, mordenite carbon membranes yielded a water/ethanol separation factor of 990.37 at a water flux of 9.10 g/m2h. The influence of the operating temperature on the performance of the membrane also was considered. It was concluded that the selective adsorption of water through zeolite pores was achieved. The entire preparation procedure was achieved using a rapid, low-cost preparation process.

scholarly journals Exploring and Exploiting the Symmetry-Breaking Effect of Cyclodextrins in Mechanomolecules

Symmetry ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1249 ◽  
Author(s):  
Bruns
Keyword(s):  
Symmetry Breaking ◽  
Chemical Synthesis ◽  
Low Cost ◽  
Molecular Machine ◽  
Advanced Materials ◽  
Breaking Effect ◽  
Planar Chirality ◽  
Conical Shape ◽  
Wide Availability ◽  
Molecular Rings

Cyclodextrins (CDs) are cone-shaped molecular rings that have been widely employed in supramolecular/host–guest chemistry because of their low cost, high biocompatibility, stability, wide availability in multiple sizes, and their promiscuity for binding a range of molecular guests in water. Consequently, CD-based host–guest complexes are often employed as templates for the synthesis of mechanically bonded molecules (mechanomolecules) such as catenanes, rotaxanes, and polyrotaxanes in particular. The conical shape and cyclodirectionality of the CD “bead” gives rise to a symmetry-breaking effect when it is threaded onto a molecular “string”; even symmetrical guests are rendered asymmetric by the presence of an encircling CD host. This review focuses on the stereochemical implications of this symmetry-breaking effect in mechanomolecules, including orientational isomerism, mechanically planar chirality, and topological chirality, as well as how they support applications in regioselective and stereoselective chemical synthesis, the design of molecular machine prototypes, and the development of advanced materials.

New Gel Aggregates To Improve Sweep Efficiency During Waterflooding

2011 ◽  
Vol 14 (01) ◽  
pp. 120-128 ◽  
Author(s):  
Guanglun Lei ◽  
Lingling Li ◽  
Hisham A. Nasr-El-Din
Keyword(s):  
Low Cost ◽  
Oil Production ◽  
High Water ◽  
Resistance Factor ◽  
Water Production ◽  
Sweep Efficiency ◽  
Low Viscosity ◽  
Productivity Decline ◽  
High Water Cut ◽  
Water Cut

Summary A common problem for oil production is excessive water production, which can lead to rapid productivity decline and significant increases in operating costs. The result is often a premature shut-in of wells because production has become uneconomical. In water injectors, the injection profiles are uneven and, as a result, large amounts of oil are left behind the water front. Many chemical systems have been used to control water production and improve recovery from reservoirs with high water cut. Inorganic gels have low viscosity and can be pumped using typical field mixing and injection equipment. Polymer or crosslinked gels, especially polyacrylamide-based systems, are mainly used because of their relatively low cost and their supposed selectivity. In this paper, microspheres (5–30 μm) were synthesized using acrylamide monomers crosslinked with an organic crosslinker. They can be suspended in water and can be pumped in sandstone formations. They can plug some of the pore throats and, thus, force injected water to change its direction and increase the sweep efficiency. A high-pressure/high-temperature (HP/HT) rheometer was used to measure G (elastic modulus) and G" (viscous modulus) of these aggregates. Experimental results indicate that these microspheres are stable in solutions with 20,000 ppm NaCl at 175°F. They can expand up to five times their original size in deionized water and show good elasticity. The results of sandpack tests show that the microspheres can flow through cores with permeability greater than 500 md and can increase the resistance factor by eight to 25 times and the residual resistance factor by nine times. The addition of microspheres to polymer solutions increased the resistance factor beyond that obtained with the polymer solution alone. Field data using microspheres showed significant improvements in the injection profile and enhancements in oil production.

Synthesis and characterization of hyperbranched poly (sulfone-amine) modified β-cyclodextrin

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Liang Chen ◽  
Peng He ◽  
Zhifeng Jia ◽  
Xinyuan Zhu ◽  
Deyue Yan
Keyword(s):  
Drug Delivery ◽  
Low Cost ◽  
Food Additives ◽  
Synthesis And Characterization ◽  
Good Solubility ◽  
Low Viscosity ◽  
Hyperbranched Poly ◽  
Potential Applications ◽  
Inclusion Ability

AbstractAn economical strategy to prepare hyperbranched poly(sulfone-amine) modified β-cyclodextrins (HPSA-m-CDs) from natural β-cyclodextrin (β-CD) and other commercially available materials has been reported. The final product has many good properties of hyperbranched poly(sulfone-amine)s (good solubility, low viscosity etc.), while its inclusion ability can also be well kept. It is a feasible approach to prepare functionalized modified cyclodextrin at very low cost, and may have potential applications in the fields of catalysis, drug delivery, food additives, etc.

scholarly journals Reference Voltage Supply Source with Expanded Operating Temperature Range

2018 ◽  
Vol 3 (6) ◽  
pp. 213
Author(s):  
A V Popova ◽  
V M Kisel ◽  
A Yu Malyavina ◽  
A S Bakerenkov ◽  
Yu R Shaltaeva
Keyword(s):  
Operating Temperature ◽  
Reference Voltage ◽  
Supply Source ◽  
Voltage Supply ◽  
Temperature Range ◽  
Operating Temperature Range

.

scholarly journals Ultralow-temperature-driven water-based sorption refrigeration enabled by low-cost zeolite-like porous aluminophosphate

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Zhangli Liu ◽  
Jiaxing Xu ◽  
Min Xu ◽  
Caifeng Huang ◽  
Ruzhu Wang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Water Sorption ◽  
High Performance ◽  
Global Climate ◽  
Low Cost ◽  
Cost Effective ◽  
High Water ◽  
Coefficient Of Performance ◽  
High Efficient ◽  
Water Based

AbstractThermally driven water-based sorption refrigeration is considered a promising strategy to realize near-zero-carbon cooling applications by addressing the urgent global climate challenge caused by conventional chlorofluorocarbon (CFC) refrigerants. However, developing cost-effective and high-performance water-sorption porous materials driven by low-temperature thermal energy is still a significant challenge. Here, we propose a zeolite-like aluminophosphate with SFO topology (EMM-8) for water-sorption-driven refrigeration. The EMM-8 is characterized by 12-membered ring channels with large accessible pore volume and exhibits high water uptake of 0.28 g·g−1 at P/P0 = 0.2, low-temperature regeneration of 65 °C, fast adsorption kinetics, remarkable hydrothermal stability, and scalable fabrication. Importantly, the water-sorption-based chiller with EMM-8 shows the potential of achieving a record coefficient of performance (COP) of 0.85 at an ultralow-driven temperature of 63 °C. The working performance makes EMM-8 a practical alternative to realize high-efficient ultra-low-temperature-driven refrigeration.

scholarly journals DETERMINATION OF FORMATION REGIMES FOR BILAYER COBALT DYSPROSIUM INTERMETALIC SURFACE ALLOY

2019 ◽  
Vol 6 ◽  
pp. 3-8
Author(s):  
Vadym Kovalenko ◽  
Denis Kondratyev ◽  
Valerii Kotok ◽  
Olga Chernova ◽  
Ihor Kovalenko ◽  
...  
Keyword(s):  
Low Cost ◽  
Construction Materials ◽  
Development Stage ◽  
Mass Change ◽  
High Tech ◽  
Technological Parameters ◽  
Specific Mass ◽  
Temperature Range ◽  
Diffusion Layers ◽  
Modern Development

High tech industrial fields on modern development stage are in need of construction materials with an optimal ratio of volume and surface properties, along with low cost of material itself. As evidenced by studies, in order to give a set complex of properties to a workpiece that operates under specific conditions, it is often sufficient to only modify its surface area. Over the course of studies, by means of gravimetric, influence of technological parameters (temperature and time samples are kept in the melt) on specific mass change of cobalt samples, that act as substrate, during electroless diffusive saturation with dysprosium in eutectic melt of lithium and potassium chlorides have been studied. A mathematical dependency was established for specific mass change of cobalt samples on time spent in melt for temperature range of 873–973 K. Composition of intermetallic coats obtained on surface of cobalt samples was studied means of EDX and SEM analyses. It was discovered, that for chosen temperature range, diffusion layers formed on surface of cobalt samples consists of two structural zones that correspond to Co-Dy and Cp2Dy phases.

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