High-temperature Condensation Research Articles

Experimental Performance of a Membrane Desorber Operating under Simulated Warm Weather Condensation Temperatures.

In absorption systems using the aqueous lithium bromide mixture, the Coefficient of Performance is affected by the desorber. The main function of this component is to separate the refrigerant fluid from the working mixture. In conventional boiling desorbers, constant heat flux and vacuum pressure conditions are necessary to carry out the desorption process, and usually, the absorbers are heavy and bulky; thus, they are not suitable in compact systems. In this study, a membrane desorber was evaluated, operating at atmospheric pressure conditions with a water/lithium bromide solution with a concentration of 49.6% w/w. The effects of the solution temperature, solution mass flow, and condensation temperature on the desorption rate were analyzed. The maximum desorption rate value was 6.1 kg/m2h with the following operation conditions: the solution temperature at 95.2 °C, the solution mass flow at 4.00 × 10−2 kg/s, and the cooling water temperature at 30.1 °C. On the other hand, the minimum value was 1.1 kg/m2h with the solution temperature at 80.2 °C, the solution mass flow at 2.50 × 10−2 kg/s, and the cooling water temperature at 45.1 °C. The thermal energy efficiency, defined as the ratio between the thermal energy used to evaporate the refrigerant fluid with respect to the total thermal energy entering the membrane desorber, varied from 0.08 to 0.30. According to the results, a high solution mass flow, a high solution temperature, and a low condensation temperature lead to an increase in the desorption rate; however, a low solution mass flow enhanced the thermal energy efficiency. The proposed membrane desorber could replace a conventional boiling desorber, especially in absorption cooling systems that operate at high condensation temperatures as in warm weather regions.

Thermodynamic analysis and parametric optimization of ejector heat pump integrated with organic Rankine cycle combined cooling, heating and power system using zeotropic mixtures

Schematic diagram of ejector heat pump integrated with organic Rankine cycle combined cooling, heating and power (ORC-CCHP) system and mass fractions of (R141b/R134a) in ORC and heat pump loop, merits: great temperature glides in the high-temperature evaporator and high-temperature condenser, beneficial to generate plentiful refrigeration capacity in the heat pump loop. • Comprehensive thermal efficiency is proposed to achieve energy utilization potential substantially. • Mass fractions of zeotropic mixture, generator temperature and entrainment ratio are optimized. • R141b/R134a(55%/45%) achieves optimum mass fractions in ORC and heat pump loop. • Comparative analysis of basic ORCs, ORC with post ejector, ORC with ejector heat pump, EORC is conducted. • Ejector heat pump integrated with ORC-CCHP system is thermodynamiclly feasible and economically attractive. To improve the coefficient of performance ( COP ) of ejector refrigeration cycle (ERC), a novel ejector heat pump integrated with organic Rankine cycle combined cooling, heating and power system (ORC-CCHP) using zeotropic mixtures is established in this study. The comprehensive thermal efficiency is proposed considering exergy efficiency and heat recovery efficiency simultaneously. Results show that the entrainment ratio can be determined with the objective of exergy efficiency, while generator temperature and mass fraction of zeotropic mixture are optimized with the comprehensive thermal efficiency. With the optimized entrainment ratio of 0.2 and generator temperature of 351.15 K, R141b/R134a (55%/45%) achieves the power efficiency of 4.21%, refrigeration efficiency of 14.6% and COP of 1.12, which are considerably higher than those of pure R141b or R134a. Meanwhile, R141b/R134a with optimum mass fractions in ORC and heat pump loop can generate plentiful refrigeration capacity, great temperature glides in the high-temperature evaporator and high-temperature condenser. The comparative analysis of basic ORCs, ORC with post ejector, ORC with ejector heat pump, ORC combined with ejector (EORC) is carried out. The ejector heat pump integrated with ORC-CCHP system is thermodynamically feasible and economically attractive, thanks to optimized system parameters and optimum compositions of zeotropic mixture, giving support of new applications of ERC coupled with positive and reverse Carnot cycles.

Analysis of technological potential for utilization of waste aviation lubricating materials

The object of research is technologies for waste aviation oils and lubricants recycling and utilization. The work is devoted to the analysis of the current state and the assessment of the technological potential in the field of processing and disposal of aviation lubricants. The current state and dynamics of the market for the production and consumption of aviation lubricants are considered. The main properties and functions of aviation oils and lubricants are analyzed, the main technical requirements for them are formulated. A complex of physical and chemical processes that occur in lubricants during their operation and long-term storage, and lead to a loss of their quality, is considered. It is shown that the main factors of quality deterioration are high-temperature destruction, oxidation, polymerization and condensation of hydrocarbons, mixing with fuel, and pollution with inorganic compounds. The main ecological as well as economic problems associated with the aссamulation of waste lubricants are considered, their negative impact on the components of the environment and human health is described. So, the main negative effects are associated with their improper storage, discharge into water bodies or soils, as well as with their burning and the formation of toxic emissions. On the basis of this, the need for the development and implementation of integrated technologies for the disposal of waste lubricating materials is shown. The main directions, methods and technologies that are used for their utilization are presented. So, depending on the composition, quality and properties of waste lubricants, technologies for restoring their quality, processing technologies using them as raw materials for the production of similar petroleum products, technologies for obtaining low-quality fuels for stationary equipment based on them can be used. It is shown that the development and application of effective technologies for the disposal of used lubricants has a number of positive effects: minimization of the negative impact on the environment, savings and expansion of oil resources for the production of commercial petroleum products, and, as a result, saving money.

A study on the condensation heat transfer coefficient of R1234ze(E) and R134a near the critical point

Industrial heat pumps have been developed to recycle surplus heat from various industrial processes for steam generation. A condenser in an industrial heat pump needs to meet the high condensation temperature. Alternative refrigerants are also needed for condensers. The objective of this study was to compare condensation heat transfer characteristics of R1234ze(E), an alternative refrigerant at high reduced pressure, and R134a, a conventional refrigerant. A test section of copper tube with a diameter of 1/2 inch and a length of 4 m was used. The test section was installed inside a PVC tube which was cooled with brine. Experimental conditions were: reduced pressure from 0.5 to 0.7 and mass flux of 500–600 kgm-2s-1. Condensation heat transfer coefficients of R1234ze(E) and R134a decreased with an increase in reduced pressure. Effects of mass flux on refrigerants decreased with an increase in reduced pressure. A Travis model showed the best performance for estimating condensation heat transfer coefficients of R1234ze(E) and R134a under high reduced pressure conditions.

ОБ ЭФФЕКТИВНОСТИ ПРЕДПОСЕВНОЙ ОБРАБОТКИ СЕМЯН ОЗИМОЙ ПШЕНИЦЫ НАНОЧАСТИЦАМИ МЕТАЛЛОВ

The use of nanotechnologies in agriculture is an advanced course enabling to reduce the dependence of crop tonnage and quality on external factors. A special section is represented by studies of pre-sowing treatment of seeds with metal nanoparticles (NPs). In this work, it is shown for the first time that pre-sowing treatment of seeds with metal nanoparticles with specific physicochemical parameters affects morphometric indices of the of winter wheat growth at all stages of its development as well as the plant resistance to pathogens, grain quality, the degree of its damage from fusarium and elemental composition of the soil after harvesting. Effects depend on the type of metal used. Our aims were to study i) effects of pre-sowing seed treatment with iron, zinc, and copper NPs on the growth parameters and grain quality of winter wheat, and ii) whether this treatment affects the soil after harvest. Iron, zinc, and copper NPs were obtained by the method of high temperature condensation at the Migen-3 apparatus (Institute of Energy Problems of Chemical Physics RAS, Russia). The shape and size of NPs were evaluated by JSM-7401F scanning electron microscope (JEOL Ltd., Japan). X-ray phase analysis was carried out using an ADP-1 X-ray analyzer (NPO Modern Technologies of Non-Destructive Control, Russia). Field trials were carried out at the validation test site of the Novokuban Branch of the Rosinformagrotech (Krasnodar Territory). The predominant soil type is typical chernozem, with medium humus content, heavy loamy. The sowing of winter wheat (Triticum aestivum L.) cv. Stan was performed on October 4, 2016 with a setting seed rate 240 kg/h. The assigned treatments were as follows: control (seeds without treatment), seed treatment with Fe NPs (5×10-4 %), Zn NPs (1×10-4 %), Cu NPs (5×10-7 %); Fe NPs + Zn NPs + Cu NPs (5×10-4 % + 1×10-4 % + 5×10-7 %). Soil samples were collected for chemical analysis. For phenological and biometric observations, plants were taken from three locations of 1 m2 area from each experimental and control plot. Plant height, average root length, thickness of the main stem at the plant bottom, tillering and depth of the tillering node were measured. Iron, zinc, and copper NPs were round single-crystal structures covered with a semitransparent oxide film. Average diameter of Fe NPs was 27.0±0.51 nm, Zn NPs 54.0±2.8 nm, Cu NPs 79.0±1.24 nm. X-ray phase analysis showed that iron NPs consisted of 53.6 % crystalline metal phase, Fe3O4 content was 46.4 %, and the oxide film thickness was 3.5 nm. Cu and Zn NPs contained only crystalline metal phases with the similar oxide film thickness, 0.5 to 1.0 nm. Pre-sowing treatment of seeds with Fe NPs affected the height of seedlings, promoted the formation of a developed root system with total root length being 4.5 % more (р ≤ 0.05) than in the control group, and increased the seedling stand density by 9.96 % (р ≤ 0.05) vs. control. Pre-harvest monitoring of crops revealed an increase in the yield of wheat plant mass after pre-sowing seed treatment with Fe and Cu NPs. Stem length was larger than that of the control (81.3±1.2 sm) by 3.8 and 8 cm, respectively, the average thickness of the main stem at the plant bottom being larger by 6 mm (when processing with Fe NPs) and 5 mm (when treating with Cu NPs) in comparison with the control (44 mm). Plant stands productivity enhancement after Fe and Zn NPs treatments, higher resistance to pathogens (by 3.85 times vs. control) under Fe NPs, a tendency to an increase in the average 1000-grain weight when using NPs of Fe, Zn, and Cu were observed. The crop quality parameters had higher values as compared to the control: in terms of the content of wet gluten by 6.12 % when seeds were treated with Zn and Cu NPs or with NPs composition; the protein mass fraction was larger under treatment with Cu NPs and the NPs composition by 5.1 % vs. control. Pre-sowing treatment with Fe and Zn NPs reduced the prevalence of Fusarium infection in grain by 1.24 and 2.25 times respectively vs. control. Elemental analysis of the soil after harvesting showed a decrease in the content of mobile forms of phosphorus by 27 % and zinc by 48 % after seed treatment with Zn NPs in comparison with the control, and a decrease in the phosphorus mobile forms by 23 % and sulfur by 7 % after pre-sowing treatment with Cu NPs in comparison with the control. The data obtained demonstrate the effective influence of the pre-sowing treatment of seeds by metal NPs on the growth, development and grain quality of wheat.

STIMULATING EFFECTS OF PRE-SOWING SEED TREATMENT WITH METAL NANOPARTICLES ON WINTER WHEAT GROWTH AND DEVELOPMENT

The use of nanotechnologies in agriculture is an advanced course enabling to reduce the dependence of crop tonnage and quality on external factors. A special section is represented by studies of pre-sowing treatment of seeds with metal nanoparticles (NPs). In this work, it is shown for the first time that pre-sowing treatment of seeds with metal nanoparticles with specific physicochemical parameters affects morphometric indices of the of winter wheat growth at all stages of its development as well as the plant resistance to pathogens, grain quality, the degree of its damage from fusarium and elemental composition of the soil after harvesting. Effects depend on the type of metal used. Our aims were to study i) effects of pre-sowing seed treatment with iron, zinc, and copper NPs on the growth parameters and grain quality of winter wheat, and ii) whether this treatment affects the soil after harvest. Iron, zinc, and copper NPs were obtained by the method of high temperature condensation at the Migen-3 apparatus (Institute of Energy Problems of Chemical Physics RAS, Russia). The shape and size of NPs were evaluated by JSM-7401F scanning electron microscope (JEOL Ltd., Japan). X-ray phase analysis was carried out using an ADP-1 X-ray analyzer (NPO Modern Technologies of Non-Destructive Control, Russia). Field trials were carried out at the validation test site of the Novokuban Branch of the Rosinformagrotech (Krasnodar Territory). The predominant soil type is typical chernozem, with medium humus content, heavy loamy. The sowing of winter wheat (Triticum aestivum L.) cv. Stan was performed on October 4, 2016 with a setting seed rate 240 kg/h. The assigned treatments were as follows: control (seeds without treatment), seed treatment with Fe NPs (5×10-4 %), Zn NPs (1×10-4 %), Cu NPs (5×10-7 %); Fe NPs + Zn NPs + Cu NPs (5×10-4 % + 1×10-4 % + 5×10-7 %). Soil samples were collected for chemical analysis. For phenological and biometric observations, plants were taken from three locations of 1 m2 area from each experimental and control plot. Plant height, average root length, thickness of the main stem at the plant bottom, tillering and depth of the tillering node were measured. Iron, zinc, and copper NPs were round single-crystal structures covered with a semitransparent oxide film. Average diameter of Fe NPs was 27.0±0.51 nm, Zn NPs 54.0±2.8 nm, Cu NPs 79.0±1.24 nm. X-ray phase analysis showed that iron NPs consisted of 53.6 % crystalline metal phase, Fe3O4 content was 46.4 %, and the oxide film thickness was 3.5 nm. Cu and Zn NPs contained only crystalline metal phases with the similar oxide film thickness, 0.5 to 1.0 nm. Pre-sowing treatment of seeds with Fe NPs affected the height of seedlings, promoted the formation of a developed root system with total root length being 4.5 % more (р ≤ 0.05) than in the control group, and increased the seedling stand density by 9.96 % (р ≤ 0.05) vs. control. Pre-harvest monitoring of crops revealed an increase in the yield of wheat plant mass after pre-sowing seed treatment with Fe and Cu NPs. Stem length was larger than that of the control (81.3±1.2 sm) by 3.8 and 8 cm, respectively, the average thickness of the main stem at the plant bottom being larger by 6 mm (when processing with Fe NPs) and 5 mm (when treating with Cu NPs) in comparison with the control (44 mm). Plant stands productivity enhancement after Fe and Zn NPs treatments, higher resistance to pathogens (by 3.85 times vs. control) under Fe NPs, a tendency to an increase in the average 1000-grain weight when using NPs of Fe, Zn, and Cu were observed. The crop quality parameters had higher values as compared to the control: in terms of the content of wet gluten by 6.12 % when seeds were treated with Zn and Cu NPs or with NPs composition; the protein mass fraction was larger under treatment with Cu NPs and the NPs composition by 5.1 % vs. control. Pre-sowing treatment with Fe and Zn NPs reduced the prevalence of Fusarium infection in grain by 1.24 and 2.25 times respectively vs. control. Elemental analysis of the soil after harvesting showed a decrease in the content of mobile forms of phosphorus by 27 % and zinc by 48 % after seed treatment with Zn NPs in comparison with the control, and a decrease in the phosphorus mobile forms by 23 % and sulfur by 7 % after pre-sowing treatment with Cu NPs in comparison with the control. The data obtained demonstrate the effective influence of the pre-sowing treatment of seeds by metal NPs on the growth, development and grain quality of wheat.

Trace Element Conundrum of Natural Quasicrystals

We report laser ablation inductively coupled plasma mass spectrometry measurements of the trace element contents of the two naturally occurring quasicrystalline minerals, Al63Cu24Fe13 icosahedrite and Al71Ni24Fe5 decagonite, from their type locality in the Khatyrka meteorite. The isolated quasicrystal fragments were mounted separately from any matrix and are larger than the laser beam diameter. When the elements are sorted in order of volatility, a systematic and unique pattern emerges in both bulk natural quasicrystal specimens. They are highly depleted compared to primitive solar system materials (chondritic meteorites) in moderately refractory elements (those with 50% condensation temperatures near 1350–1300 K; V, Co, Mg, Cr) and significantly enriched in moderately volatile elements (those with 50% condensation temperatures between 1250 and 500 K; Sb, B, Ag, Sn, Bi). We compare the chondrite-normalized trace element patterns and ratios of the quasicrystals to those of scoriaceous cosmic spherules and other meteoritic components. The nonmonotonic shapes of the chondrite-normalized trace element patterns in both icosahedrite and decagonite are incompatible with a single condensation process from the gas of the solar nebula. Previous transmission electron microscopy studies show that the natural quasicrystals contain 3–5 vol % of silicate and oxide nanoparticle inclusions, which we consider to be the main host of the measured trace elements. On this basis, we construct a three-stage model for the formation of the quasicrystals and their inclusions: a high-temperature condensation stage and a low-temperature vapor-fractionation stage to make nanoparticles, followed by a third stage that leads to the formation of quasicrystals incorporating the two different types of nanoparticles and their incorporation into the CV chondrite parent body of the Khatyrka meteorite.

The valorization of co-pyrolysis bio-oil derived from bio-oil distillation residue and walnut shell via coupling fractional condensation and lyophilization

In this study, walnut shells and bio-oil distillation residues were co-pyrolyzed at varying ratios (i.e. 1:3, 1:1, and 3:1) and the resulting bio-oils were collected via fractional condensation. Furthermore, the effect of lyophilization on the collected bio-oils was analyzed. The results indicated that the temperature of fractional condensation effectively controlled the co-pyrolytic oil yield in first condenser, while the total bio-oil yield and condensation efficiency were dominated by the co-pyrolytic blend mass ratios. Meanwhile, the lower ratio of mixed walnut shell and higher condensation temperature would improve the element distribution of bio-oil, namely weakened oxygen content and intensified carbon content. Moreover, the introduction of bio-oil distillation residue not only decreased the content of carboxylic acids in co-pyrolytic oils, but also accelerated the conversion of lignin oligomers to aromatic monomers. The product distribution of fractional co-pyrolytic oil was also improved, in which the total detectable phenols enhanced to 9.73 wt% (with a maximum increase of 22.79 times). Additionally, lyophilization had a positive effect on separation and purification of aqueous bio-oil, endowing 4.79–10.81 times enhancement of detectable phenols and exhibiting a maximum increase of furfural content as surprising 2.22 wt%.

Fuel Aromaticity Promotes Low-Temperature Nucleation Processes of Elemental Carbon from Biomass and Coal Combustion.

Significant elemental carbon (EC) emissions from low-temperature solid fuel combustion cannot be explained by classical mechanisms ascribing EC to higher-temperature condensation (> 850 °C). The importance of fuel composition in promoting EC nucleation was investigated by studying EC and polycyclic aromatic hydrocarbon (PAH) formation at multiple-ignition temperatures (300-900 °C) using fuels with different aromatic contents (i.e., straw, wood, and coal). Biomass and coal combustion at 300 °C can produce substantial EC containing a large amount of soot-EC, a known high-temperature condensation product, possibly because aromatics reduce EC nucleation barriers, corresponding to the increasing ratios of soot-EC to char-EC from straw to coal (1.22 to 3.61). High- to low-molecular-weight PAH ratios in biomass combustion were four times lower than those in coal combustion, resulting in different EC formation atmospheres. Specifically, 31.4% of PAHs from biomass combustion were indene, compared to only 0.24% for coal, indicating that resonance-stabilized hydrocarbon-radical chain reactions dominated EC nucleation in biomass combustion. Five- to six-membered PAH ratios were always higher than one in biomass combustion but increased significantly from 0.5 to 2 with increasing temperature in coal combustion, indicating that PAHs generated through aromatic decomposition in coal could form EC through van-der-Waals forces and phenyl addition/cyclization-based covalent bonding at low and high temperatures, respectively.

Application Research on Energy Saving Technology of Waste Heat Recovery and Defrosting for Low Temperature Cold Storage

In this paper, a glycol defrosting system using waste heat exhaust from refrigeration compressor is designed. The defrosting numerical model, heat transfer model and frost growth model were established. The frost thickness, defrosting heat consumption and ethylene glycol flow rate were calculated, and the ethylene glycol pipeline was designed. The project solves the problems of traditional defrosting of cold storage, such as high power consumption, fluctuation of storage temperature, hidden danger of safety, high condensation temperature and low efficiency of refrigeration system.

Native Iron Nodules in Basites - Xenoliths of the Earth Core

Summary of the published data has shown that native iron nodules, which are rarely found in the basic intrusions, are characterized by a higher content of low-temperature condensates of the protoplanetary disk (Ge, Ag, Cu) and a lower content of high-temperature condensates (Os, Ir, Ru, Pt, Rh, Pd, Ni, Co, Au) compared to iron meteorites. Such meteorites have signs of formation from the fragments of the cores of minor planets. This fact and obtained evidence of hot heterogeneous accretion of the Earth, the early formation of the Earth’s core compared to the mantle and the growth of the primary content of low-temperaGture condensates from the inner parts of the core to the outside suggest the capture and the ascent of substance of outer core by mantle plumes, and basic magmas formed in them. This explains the peculiarities of their composition, their very rare presence in basites, and sometimes a huge mass of nodules (up to tens of tons). In case of such xenogenic origin, nodules of native iron are chemically unequilibrium with basites. This is the reason of the development of reaction cohenite-magnetite and cohenite-sulfide rims on their contact and an increase of ferruginosity of olivine in basites. The formation of the lower mantle material from the earliest high-temperature condensates of the protoplanetary disk explains the decreased content of potassium, sodium, water, and other lithophile components in the nodule-containing basites. The content of volatile components lowers the crystallization temperature of melts. Therefore, the loss of them under the influence of decompression at the low-depth stages of ascent led to rapid solidification of magmas, protected the iron nodules from subsidence, and explains their location mainly in the upper parts of the main intrusions, despite the high density of iron.

Review and experimental study on performance improvement of split air conditioner by reducing inlet air temperature to the ODU

Split Air Conditioners (ACs) are more commonly use now a days in residential and commercial buildings for achieving thermal comfort in all seasons. Split ACs works on well-known VCR (Vapour Compression Refrigeration) cycle. Split ACs used more in summer season and due to high outside temperature condenser pressure in a VCR cycle and ultimately result in to high electricity consumption. One of the way to reduce energy consumption of Split ACs and increase cooling capacity is reduce air temperature entering to the condenser in ODU using evaporative cooling principle. In this paper detailed review have been carried out for the improvement of split air conditioner performance and experimental study conducted on Split AC (0.8 TR cooling capacity) with and without evaporative cooling pad at ODU. Evaporative cooling pad material and thickness have been varied to analyse their effects on cooling capacity and coefficient of performance (COP) of Split AC. Out of the PVC, Grass and Cellulose cooling pad of same thickness 150 mm, cellulose cooling pad at ODU of Split AC results about 2 bar reduction in condenser pressure and 1.5 KWH energy saving for 10 hours of operation in a day. Split AC with 100 mm thick cooling pad of cellulose material at ODU results in to approximately 16% increase in overall COP, 10.8 % increase in cooling capacity and 4.6 % reduction in power consumption and at 32°C DBT and about 35% RH outdoor weather condition.

Comparison of Conventional and Advanced Exergy Analysis for Dual-Loop Organic Rankine Cycle used in Engine Waste Heat Recovery

At present, the dual-loop organic Rankine cycle (DORC) is regarded as an important solution to engine waste heat recovery (WHR). Compared with the conventional exergy analysis, the advanced exergy analysis can better describe the interactions between system components and the irreversibility caused by economic or technical limitations. In order to systematically study the thermodynamic performance of DORC, the conventional and advanced exergy analyses are compared using an inline 6-cylinder 4-stroke turbocharged diesel engine. Meanwhile, the sensitivity analysis is implemented to further investigate the influence of operating parameters on avoidable-endogenous exergy destruction. The analysis result of conventional exergy analysis demonstrates that the priorities for the components that should be improved are in order of the high-temperature evaporator, the low-temperature turbine, the first low-temperature evaporator and the high-temperature condenser. The advanced exergy analysis result suggests that the avoidable exergy destruction values are the highest in the low-temperature turbine, the high-temperature evaporator and the high-temperature turbine because they have considerable endogenous-avoidable exergy destruction. The sensitivity analysis indicates that reducing the evaporation pinch point and raising the turbine efficiency can decrease the avoidable exergy destruction.

Integration of Municipal Air-Conditioning, Power, and Gas Supplies Using an LNG Cold Exergy-Assisted Kalina Cycle System

A Kalina cycle-based integration concept of municipal air-conditioning, electricity and gas is investigated thermodynamically, economically, and environmentally to reduce the carbon intensity of these supplies, with attention to hot climatic conditions. The proposed poly-generation system is driven by low-grade renewable or surplus heat, and utilizes waste exergy from liquefied natural gas vaporization for refrigeration and power augmentation. At nominal conditions (130 °C driving heat), approximately 561 and 151 kJ of refrigeration and useful power per kg of liquefied natural gas regasified are generated by the proposed system, respectively, at effective first-law and exergetic efficiencies of 33% and 35%, respectively. The Kalina sub-system condenser cryogenic heat rejection condition is found to triple the system useful electrical output compared with high ambient temperature condenser heat sinking conditions. Per million ton per annum of liquefied natural gas vaporization capacity, yearly net power savings of approximately 74 GWhe could be achieved compared to standard air-conditioning, electricity, and gas supply systems, resulting in 11.1 kton of natural gas saved and 30.4 kton of carbon dioxide-equivalent emissions avoided annually. The yearly net monetary savings would range from 0.9 to 4.7 million USD per million ton per annum of liquefied natural gas regasified at local subsidized and international electricity market prices, respectively, with corresponding payback periods of 1.7 and 2.5 years, respectively.

A High-Temperature Impact Condensate of the Lonar Crater (India)

A high-calcium high-temperature condensate is detected in the Earth’s impact Lonar crater for the first time. Its finding confirms in practice the theoretical conclusions made earlier from the experimental results. The high-silica condensate found in the Lonar crater, which is similar to those ones in the Zhamanshin crater and in the lunar regolith, confirms the absence of a correlation between the compositions of the target and the impact condensates. The presence of high-temperature condensate glasses in ring structures may be one of the diagnostic criteria to differentiate between volcanogenic and impact formations.

A combined heat, hydrogen and power tri-generation system based on the use of catalytic membrane reactors with a dual-loop organic Rankine cycle

A dual-loop organic Rankine cycle (D-ORC) was used to recover waste heat from a biomass gasification process, for combined heat, hydrogen, and power (CHHP) generation. The process is based on the integration of biomass gasification with catalytic partial oxidation (CPO) and water-gas shift catalytic membrane reactors (WGS CMRs) for the simultaneous production and separation of hydrogen. The high temperature loop of the ORC was used to cool the CPO reactor effluent, while the low temperature loop was used to cool the WGS CMR retentate. Energy and exergy analyses were carried out to select the optima working fluids for this application. Hydrocarbons, siloxanes, hydrofluorocarbons (HFCs), and hydrofluoroolefins (HFOs) were examined as potential candidates in this analysis. Results indicate that the highest efficiency was obtained when n-heptane and n-pentane were used as working fluids for the high and low temperature loops, respectively. Using this combination, electric and exergy efficiencies of 13.93% and 36.41% were computed, receptively. The process generates 1.37 kW of power, and produces 1.41 kg/hr of hydrogen at 773 K and 91.32 kg/hr of hot water at 363 K. The exergy analysis has also showed that the high temperature loop turbine and condenser have contributed the most, by around 32%, to the overall system irreversibility.

An evolutionary system of mineralogy. Part II: Interstellar and solar nebula primary condensation mineralogy (>4.565 Ga).

(1)Varied crystalline and amorphous molecular solids containing primarily H, C, O, and N are observed to condense in cold, dense molecular clouds in the interstellar medium (10 < T < 20 K; P < 10-13 atm). With the possible exception of some nanoscale organic condensates preserved in carbonaceous meteorites, the existence of these phases is documented primarily by telescopic observations of absorption and emission spectra of interstellar molecules in radio, microwave, or infrared wavelengths. (2)Evidence from infrared observations and laboratory experiments suggest that cubic H2O ("cubic ice") condenses as thin crystalline mantles on oxide and silicate dust grains in cool, distant nebular and circumstellar regions where T ~100 K. (3)The earliest phase of nebular mineralogy saw the formation of primary refractory minerals that solidified through high-temperature condensation (1100 < T < 1800 K; 10-6 < P < 10-2 atm) in the solar nebula more than 4.565 billion years ago. These earliest mineral phases originating in our solar system formed prior to the accretion of planetesimals and are preserved in calcium-aluminum-rich inclusions, ultra-refractory inclusions, and amoeboid olivine aggregates.

Parametric analysis and thermo-economical optimization of a Supercritical-Subcritical organic Rankine cycle for waste heat utilization

The Supercritical-Subcritical organic Rankine cycle could combine the superiorities of supercritical ORC and dual-pressure organic Rankine cycle to recover more heat and improve the system performance. The parametric analysis and thermo-economical optimization of a Supercritical-Subcritical organic Rankine cycle using R1234ze has been investigated in this study. The effects of five key operation parameters on the thermodynamic performance and economical factor are examined. A single-objective optimization for maximizing net work output, maximizing exergy efficiency and minimizing UAsys (heat transfer requirement) is examined and compared. The bi-objective optimization for maximizing exergy efficiency and minimizing UAsys simultaneously is also addressed. Research demonstrates that the net output power increases first and then decreases as supercritical stage temperature and supercritical stage pressure. UAsys decreases first and then increases with the supercritical stage temperature. The lower UAsys does not mean the higher net power output or exergy efficiency. A higher supercritical stage pressure and temperature are detrimental to system economic performance, while a higher condensation temperature can benefit improving system economic performance. The Pareto-optimal solutions for exergy efficiency and UAsys are 61.25% and 20.08 kW/K, respectively.

Fire safety improvement of pyrotechnic nitrate-metal mixtures under external thermal conditions

The object of research is the effect of the ratio of the components of the pyrotechnic mixtures and the pressure of the environment on the temperature of the products of combustion and their content in high-temperature condensate. This topic has its relevance due to the recent increase in the world of pyrotechnic articles of various purposes. One of the most problematic areas is the violation of fire safety rules during their storage, transportation and use. In these modes, their premature operation, resulting in the formation of high-temperature condensed combustion products. These substances collide in different directions and pose a fire hazard to the surrounding objects (buildings and structures of various purposes, timber structures, forests, parks, etc.). The study used a database on the temperature of combustion products of pyrotechnic mixtures and their contents in high-temperature condensate, which determine their properties in relation to fire risk during operation in external conditions. The data in the study were obtained as a result of standard thermodynamic calculations and were collected using known multiple correlation and regression methods in the form of statistical models. The obtained calculations established a significant influence of the ratio of the components of the pyrotechnic mixtures and the pressure of the environment on the temperature of their combustion products and their content in high-temperature condensate, which allowed to determine the optimal ranges of parameters of change. This ensures new results. For comparison, calculations were made with separate experimental data for which tungsten-rhenium thermocouples with special screens were used to prevent the adhesion of condensed products and probes for their selection. The results showed that the differences between them did not exceed 8–10 %.

Exergy and Cost Optimization of a Two-Stage Refrigeration System Using Refrigerant R32 and R410A

Abstract An attempt has been made to investigate numerically a two-stage refrigeration system with flash intercooler of 50 kW cooling capacity using refrigerant R410A and its possible alternative R32. Development of the simulation model for the analysis of the system has been carried out in engineering equation solver considering the energetic, exergetic, economic, and environmental aspects. Evaporator and condenser temperatures have been varied from −50 °C to −25 °C and 40 °C to 55 °C, respectively, to carry out the simulation work. Co-efficient of performance (COP), exergetic efficiency, and plant cost rate are the three performance parameters computed in this present work. Results show that the performances of the system using R32 are comparable with those of the system using R410A. It is also observed that R32 shows slightly better thermo-economic performances at higher condenser temperature. Multi-objective optimization has also been carried out using the toolbox available for optimization in matlab to obtain the optimum performance and optimum operating conditions for both the refrigerants. Optimization results also show better thermo-economic performances of R32 over R410A though compressor discharge temperature is higher in case of R32.