Different Concentrations Of CO2 Research Articles

Chamberless NDIR CO2 Sensor Robust against Environmental Fluctuations.

Accuracy of CO2 measurement is affected by ambient air fluctuations, making the compensation of such variations in drift-like sensor response essential for concentration level assessment. Here, a series of experiments were carried out with a chamberless approach in a nondispersive infrared (NDIR) gas sensor to examine the combined effect of environmental temperature and relative humidity fluctuations on sensor responses at different concentrations of CO2. To eliminate the drift-like terms caused by environmental fluctuations, the behavior of the sensor was modeled to include ambient temperature, relative humidity, the measured responses as the inputs, and the concentration level as the output. The sensor was fabricated by a light source with an embedded parabolic reflector, a thermopile detector, and two reflective walls that are exposed to the applicable range of CO2 gas. The predicted concentration level was determined by analyzing the system and acquiring a heuristic function based on an ensemble regression model. The created model's reliability and sensor's performance were evaluated by the test and validation data, and the respective accuracies of 99.83 and 98.90% demonstrated the model effectiveness. The chamberless structure of the sensor provides reduction in diffusion time, improves the linearity of responses accompanied by eliminating drift-like variation of responses in varying ambient conditions, and prepares the sensor for industrial applications.

Improved Sensing Properties of Thermal Conductivity-Type CO2 Gas Sensors by Loading Multi-Walled Carbon Nanotubes Into Nano-Al2O3 Powders

Response time is the key index of on-line monitoring system. To improve the response speed of traditional bead thermal conductivity CO2 sensor, this paper proposes to use multi-walled carbon nanotubes (MWCNTs) to improve the performance of gas sensor carrier. Nano-sized γ-Al2O3/CeO2 powder was synthesized by chemical precipitation method under the action of ultrasonic wave. SEM morphology reveals a particle size of 20–50 nm. MWCNTs were hydroxylated and the solution was then prepared by adding a certain amount of dispersant under ultrasonic wave. The composite support of γ- Al2O3/CeO2/MWCNTs was prepared by wet mixing carbon nanotube solution into the above support materials. Using dynamic resistance matching and black component technology, the influence of radiation heat and environmental temperature and humidity is reduced. Results show that the designed thermal conductivity sensor has consistent response and recovery time to different concentrations of CO2, with a T90 response time of 9 s and a T90 recovery time of 13 s, which is faster compared to major commercial Carbon dioxide sensors. The average sensitivity of the sensor is 0.0075 V/10% CO2. Therefore, the high thermal conductivity and pore characteristics of carbon nanotubes can effectively improve the response speed of the thermal conductivity sensor.

Mosquito Host Seeking in 3D Using a Versatile Climate-Controlled Wind Tunnel System.

Future anthropogenic climate change is predicted to impact sensory-driven behaviors. Building on recent improvements in computational power and tracking technology, we have developed a versatile climate-controlled wind tunnel system, in which to study the effect of climate parameters, including temperature, precipitation, and elevated greenhouse gas levels, on odor-mediated behaviors in insects. To establish a baseline for future studies, we here analyzed the host-seeking behavior of the major malaria vector mosquito, Anopheles gambiae sensu strico, to human odor and carbon dioxide (CO2), under tightly controlled climatic conditions, and isolated from potential background contamination by the presence of an experimenter. When presented with a combination of human foot odor and CO2 (case study I), mosquitoes engaged in faster crosswind flight, spent more time in the filamentous odor plume and targeted the odor source more successfully. In contrast, female An. gambiae s. s. presented with different concentrations of CO2 alone, did not display host-seeking behavior (case study II). These observations support previous findings on the role of human host-associated cues in host seeking and confirm the role of CO2 as a synergist, but not a host-seeking cue on its own. Future studies are aimed at investigating the effect of climate change on odor-mediated behavior in mosquitoes and other insects. Moreover, the system will be used to investigate detection and processing of olfactory information in various behavioral contexts, by providing a fine-scale analysis of flight behavior.

Influence of Synthesis Gas Components on Hydrogen Storage Properties of Sodium Aluminum Hexahydride

A systematic study of different ratios of CO, CO2, N2 gas components on the hydrogen storage properties of the Na3AlH6 complex hydride with 4 mol% TiCl3, 8 mol% aluminum and 8 mol% activated carbon is presented in this paper. The different concentrations of CO and CO2 in H2 and CO, CO2, N2 in H2 mixture were investigated. Both CO and CO2 gas react with the complex hydride forming Al oxy-compounds, NaOH and Na2CO3 that consequently cause serious decline in hydrogen storage capacity. These reactions lead to irreversible damage of complex hydride under the current experimental condition. Thus, after 10 cycles with 0.1 vol % CO + 99.9 vol %H2 and 1 vol % CO + 99 vol %H2, the dehydrogenation storage capacity of the composite material decreased by 17.2% and 57.3%, respectively. In the case of investigation of 10 cycles with 1 vol % CO2 + 99 vol % H2 gas mixture, the capacity degradation was 53.5%. After 2 cycles with 10 vol % CO +90 vol % H2, full degradation was observed, whereas after 6 cycles with 10 vol % CO2 + 90 vol % H2, degradation of 86.8% was measured. While testing with the gas mixture of 1.5 vol % CO + 10 vol % CO2 + 27 vol % H2 + 61.5 vol % N2, the degradation of 94% after 6 cycles was shown. According to these results, it must be concluded that complex aluminum hydrides cannot be used for the absorption of hydrogen from syngas mixtures without thorough purification.

Potential CO2 capture in one-coat limestone mortar modified with Mg3Al–CO3 calcined hydrotalcites using ultrafast testing technique

• HT C2500 worsened the compressive strength of one-coat limestone mortar. • HT C2500 reduced the carbonation reaction of portlandite. • The CO 2 capture capacity increased by 8.52% upon addition of 5% HT C2500. • One m 2 of one-coat mortar modified with 5% of HTC2500 cleans 5540 m 3 of air. • An ultrafast method to quantify the maximum CO 2 capture capacity was presented. The objective of this work is to quantify the CO 2 capture capacity of an industrial one-coat limestone mortar containing different percentages of calcined Mg 3 Al–CO 3 hydrotalcite (HT C2500) added (0, 2.5, and 5%) in different hardening environments (with different concentrations of CO 2 ). The maximum CO 2 capture capacity (calculated by thermogravimetric analysis) for 0, 2.5, and 5% of added HT C2500 were 1127, 1143, and 1223 g·m −2 (as rendering), respectively. This amount of CO 2 is approximately one-third of that emitted during the manufacture of the cement used for this mortar. The addition of calcined hydrotalcite worsened the compressive strengths obtained in all the hardening environments studied. A 5% of calcined hydrotalcite increased the CO 2 capture capacity by 8.52% with respect to the reference mortar. Ultrafast testing method (using CO 2 isotherms at high pressure) has been proposed to quantify the CO 2 capture capacity in very short period of time. A slight modification in the dosage of calcined hydrotalcite in an industrial one-coat mortar can contribute to mitigating climate change.

The combined effect of CO2 and calcined hydrotalcite on one-coat limestone mortar properties

This paper studies the combined effect of different percentages of calcined hydrotalcite of Mg3Al-CO3 and different concentrations of CO2 in the curing atmosphere on the fresh and hardened properties of a commercial one-coat mortar. The workable life, fresh and dry bulk density decreased with the incorporation of calcined hydrotalcite, which (also) helped to maintain the mechanical properties of mortar over time. CO2 increased the dry bulk density, decreased the accessible porosity for water, and improved the mechanical properties of all one-coat mortar samples. Calcined hydrotalcite reduced the carbonation phenomenon which could mitigate the appearance of pathologies in the coatings.

CO2 enrichment and increasing light intensity till a threshold level, enhance growth and water use efficiency of lettuce plants in controlled environment

Carbon dioxide (CO2) and light intensity are the two main environmental drivers known to play important roles in crop growth and yield. In the current study, lettuce seedlings were exposed to four different light intensities [(75, 150, 300 and 600 Photosynthetic Photon Flux Density (PPFD)] and four different concentrations of CO2 (400, 800, 1200 and 1600 ppm). By increasing light intensity and CO2 concentration growth parameters such as fresh weight, dry weight and leaf area were stepwise increased from 75 to 300 PPFD and from 400 ppm to 1200 ppm CO2 concentration. Maximum fresh weight was observed in 300 PPFD under both 1200 ppm and 1600 ppm CO2 concentrations. Highest dry weight was obtained in plants exposed to 300 and 600 PPFD under both 1200 and 1600 ppm CO2 concentrations. Highest leaf area was detected in 300 PPFD under both 1200 and 1600 ppm CO2 concentrations. Widest stomatal pore aperture was detected in 600 PPFD under 400 ppm and 800 ppm CO2 concentrations. Evapotranspiration increased in a light intensity and CO2 concentration-dependent manner; higher light intensity or higher CO2 concentration, more evapotranspiration. Highest water use efficiency (WUE) was achieved in plants exposed to 300 PPFD under 1200 ppm CO2 concentration. In conclusion, to achieve best growth performance and WUE, lettuce should be produced under 300 PPFD light intensity and 1200 ppm CO2.

Re-Visiting the Incidence of Environmental Factors on a Pre-Imaginal Population of the Red Gum Lerp Psyllid, Glycaspis brimblecombei Moore.

Simple SummaryThe red gum lerp psyllid (Glycaspis brimblecombei) is an invasive pest of Eucalyptus trees worldwide, responsible for serious damage. A revisited analysis was carried out on data collected in eastern Sicily soon after the psyllid introduction in 2012/13. G. brimblecombei has been sampled by two different methods on Eucalyptus camaldulensis in nine different sites, where the main climatic data (air temperature, relative humidity, and precipitation) have been registered. G. brimblecombei population showed a similar trend in all nine sites, positively correlated only with air temperature. A negative correlation has emerged with precipitation and relative humidity. The results show the need for a deeper understanding of the role played by environmental factors as well as by the sampling methods based on the random collection of a fixed number of leaves, compared to methods based on the collection of infested leaves in a fixed time interval.The red gum lerp psyllid, Glycaspis brimblecombei Moore (Hemiptera: Aphalaridae), is an invasive pest of Eucalyptus trees worldwide, responsible for serious damage, including the death of plants. Knowledge about the incidence of climatic factors on the insect development are essential to define useful strategies for controlling this pest. To this aim, G. brimblecombei has been sampled by two different methods from April 2012 to February 2013 in eastern Sicily on Eucalyptus camaldulensis in nine different sites, where the main climatic data (air temperature, relative humidity, and precipitation) have been also registered. The Glycaspis brimblecombei population showed a similar trend in all nine sites, positively correlated only with air temperature, but a negative correlation has emerged with precipitation and relative humidity. The results show the need for a deeper understanding of the role played by other abiotic (such as different concentrations of CO2) and biotic (e.g., the antagonistic action of natural enemies, competition with other pests, etc.) factors. The greater sensitivity, even at low densities of psyllid, of sampling methods based on the random collection of a fixed number of leaves compared to methods based on the collection of infested leaves in a fixed time interval has been also outlined.

Development of a Tuneable NDIR Optical Electronic Nose.

Electronic nose (E-nose) technology provides an easy and inexpensive way to analyse chemical samples. In recent years, there has been increasing demand for E-noses in applications such as food safety, environmental monitoring and medical diagnostics. Currently, the majority of E-noses utilise an array of metal oxide (MOX) or conducting polymer (CP) gas sensors. However, these sensing technologies can suffer from sensor drift, poor repeatability and temperature and humidity effects. Optical gas sensors have the potential to overcome these issues. This paper reports on the development of an optical non-dispersive infrared (NDIR) E-nose, which consists of an array of four tuneable detectors, able to scan a range of wavelengths (3.1–10.5 μm). The functionality of the device was demonstrated in a series of experiments, involving gas rig tests for individual chemicals (CO2 and CH4), at different concentrations, and discriminating between chemical standards and complex mixtures. The optical gas sensor responses were shown to be linear to polynomial for different concentrations of CO2 and CH4. Good discrimination was achieved between sample groups. Optical E-nose technology therefore demonstrates significant potential as a portable and low-cost solution for a number of E-nose applications.

Colorimetry-based System for Gaseous Carbon Dioxide Detection

The study of sensing materials to the detection of carbon dioxide (CO2) was achieved using p-nitrophenol (pNPh) as a colorimetric indicator. The sensing material was polymerized (NPLn), functionalized with 3-triethoxysilyl propyl isocyanate (IPTES) which sensitivity was tested in the form of a membrane as is and encapsulated in hollow silica nanoparticles. The sensing membranes were tested in a closed gas system comprising very precise flow controllers to deliver different concentrations of CO2 (vs. N2). The combination of the sensing membranes with multimode optical fibers and a dual-wavelength diode (LED) allows the measurement of the CO2 through the analysis of the induced absorbance changes with a self-referenced ratiometric scheme. The analysis of the sensing materials have shown significant changes in their chemical and physical properties and the results attest these materials with a strong potential for assessing CO2 dynamics in environmental, medical, and industrial applications.

Diagnostic of Ar-CO2 mixture plasma using a fine-structure resolved collisional radiative model

In the present work, we develop a collisional radiative (CR) model for the Ar-CO2 mixture plasma. The model is applied to the diagnostics of a recently reported low-pressure DC generated Ar-CO2 plasma of Rodríguez et al. [Phys. Plasmas 25, 053512 (2018)] utilizing their spectroscopic measurements who reported the plasma parameters at different concentrations of CO2 in Ar at various pressures and powers. Our CR model includes various population transfer mechanisms between the fine structure levels, viz., electron-impact excitation, radiative decay, and ionization, as well as their reverse processes, e.g., electron-impact de-excitation as well as two- and three-body recombination. The effects of radiation trapping and diffusion are also taken into account. The plasma parameters viz. electron density (ne) and electron temperature (Te) are obtained as a function of different pressures (0.2, 0.3, and 0.6 mbars) and discharge powers at 25 and 50% concentrations of CO2 in argon. These results are determined using measured intensities of seven intense emission lines out of 3p54p (2pi) → 3p54s (1si) fine-structure transitions. It is observed that both the electron density and electron temperature increase with the increase of CO2 concentration, which is in confirmation with experimental predictions. The populations obtained for 1si and 2pi levels from our CR model are also reported and compared respectively with the corresponding available values from the simple CR model and experiment of Rodríguez et al. [Phys. Plasmas 25, 053512 (2018)]. A significant difference in the populations is observed from the two models.

Effect of pulsed controlled atmosphere with CO2 on the quality of watercored apple during storage

Watercored 'Fuji' apple with special water core and unique flavor is a characteristic fruit. However, the problems of water core disappearance and browning in the apples are outstanding during postharvest storage. In this study, pulsed controlled atmosphere (pCA) with CO2 was used to protect the water-core and resist browning of apples. Effects of different concentrations of CO2 on the quality of apple fruits was investigated, and CO2 injury characteristic to apple fruits were studied as well. Results showed that pCA with CO2 could effectively maintain the sensory and texture qualities of watercored apples. Treated with pulsed controlled CO2, the degree of membrane lipid peroxidation of the apples was effectively reduced and the membrane system was well maintained. Meanwhile, the activity of polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) of the apples were inhibited and the browning was reduced. On the whole, pCA with 1% CO2 presented the most significant effects on the quality preservation of watercored apples while higher CO2 showed negative effects on the quality of the samples. Under the condition of pCA with 5% CO2, the endurance of watercored apples was less than 45 days and the internal browning was serious. In conclusion, 2%～3% O2 and pCA with 1% CO2 was the best and most effective in the long-term preservation of watercored apples, and it is beneficial to guide for the preservation of apple fruits.

Characterization and gas sensing properties of graphene/polyaniline nanocomposite with long-term stability under high humidity

Graphene/polyaniline (Pani) nanocomposites (G/Pani) were prepared by in situ chemical oxidative polymerization using different (0–30 wt%) of graphene. According to the characterization, the presence of graphene in Pani matrix reduced the density of surface states and increased the defect density. The partial protonation of Pani and different wt% of graphene showed significant effect on CO2 gas sensing at room temperature and high humidity (ca. 90%). All prepared samples showed dynamic response and rapid recovery time to different concentrations of CO2. The nanocomposite with 20 wt% of graphene exhibited better protonation degree, sensitivity and reversibility to other samples. The sensor responded to 0.5 vol% CO2 gas three times bigger than Pani. The excellent long-term stability (about 18% less than the initial experiment) was obtained for the sensor based on G/Pani after 1 year, which makes it a potential candidate for application in CO2 gas sensor.

Bacterial phenotype dependency from CO2 measured by Raman spectroscopy

In recent years, Raman spectroscopy has become an established method to study medical, biological or environmental samples. Since Raman spectroscopy is a phenotypic method, many parameters can influence the spectra. One of these parameters is the concentration of CO2, as this never remains stable in nature, but always adjusts itself in a dynamic equilibrium. So, it is obvious that the concentration of CO2 cannot be controlled but it might have a big impact on the bacteria and bacterial composition in medical samples. When using a phenotypic method like Raman spectroscopy it is also important to know the influence of CO2 to the dataset. To investigate the influence of CO2 towards Raman spectra we cultivated E. coli at different concentration of CO2 since this bacterium is able to switch metabolism from aerobic to microaerophilic conditions. After applying statistic methods small changes in the spectra became visible and it was even possible to observe the change of metabolism in this species according to the concentration of CO2.

Synechococcus elongatus BDU 130192, an Attractive Cyanobacterium for Feedstock Applications: Response to Culture Conditions

Marine cyanobacteria are attractive organisms as feedstock for bioethanol and biotechnological applications. Previously, a marine cyanobacterial strain Synechococcus elongatus BDU 130192 was identified which can accumulate high polyglucan levels without the need to resort to N-deprivation. In this study, among the three different temperatures (30, 34, and 38 °C) tested, the highest biomass accumulation and total carbohydrate occur at 34 °C. The biomass and total carbohydrate increased with increasing light intensities, while protein, chlorophyll, and carotenoid contents were reduced. The best growth occurred at 1.8% NaCl concentration, even though the strain could grow well until 5.8% NaCl. Among the different concentrations of CO2 tested, the best growth occurred at 5% CO2 in the air. NaNO3 gave the best growth, though the cells were able to grow well on urea and NH4Cl too. Tripling the concentration of either N or P in the medium led to a significant increase in growth rate. The strain does not require the addition of vitamin B12 for growth, and about 90% flocculation could be achieved in an hour with the addition of chitosan. High productivities of 0.5 g/L/day of biomass and 0.23 g/L/day of carbohydrates could be reached in a 3-L photobioreactor (PBR) bubbled with air. This work shows many unique properties of this strain such as high carbohydrate productivity, ability to tolerate high light intensities and high concentrations of salt and CO2, and efficient flocculation. These properties make Synechococcus elongatus BDU 130192 an attractive candidate as a feedstock for bioethanol and biotechnological applications.

Growth of Crystalline Bimetallic Metal-Organic Framework Films via Transmetalation.

Crystalline films of the Cu3(BTC)2 (BTC3- = 1,3,5-benzenetricarboxylate) metal-organic framework (MOF) have been grown by dip-coating an alumina/Si(111) substrate in solutions of Cu(II) acetate and the organic linker H3BTC. Atomic force microscopy (AFM) experiments demonstrate that the substrate is completely covered by the MOF film, while grazing incidence wide-angle X-ray scattering (GIWAXS) establishes the crystallinity of the films. Forty cycles of dip-coating results in a film that is ∼70 nm thick with a root mean squared roughness of 25 nm and crystallites ranging from 50-160 nm in height. Co2+ ions were exchanged into the MOF framework by immersing the Cu3(BTC)2 films in solutions of CoCl2. By varying the temperature and exchange times, different concentrations of Co were incorporated into the films, as determined by X-ray photoelectron spectroscopy experiments. AFM studies showed that morphologies of the bimetallic films were largely unchanged after transmetalation, and GIWAXS indicated that the bimetallic films retained their crystallinity.

Biosorption of cobalt and its effect on growth and metabolites of Synechocystis pevalekii and Scenedesmus bernardii: Isothermal analysis

Abstract Because of their toxic potential, industrial effluents that contain cobalt ions have become a severe environmental problem, unless properly treated. This research tends to study the removal of cobalt from aqueous solution by Synechocystis pevalekii and Scenedesmus bernardii, grown at different concentrations of Co 2 + ions, and to study its impacts on growth and metabolism. With increased concentrations of Co 2 + ions, chlorophyll a, dry weight, and total lipids decreased. The highest CAT and LOX activity was observed in both tested algae at concentrations of 0.5 and 0.2 mgl−1 of Co 2 + . Langmuir, Freundlich, Temkin and Dubinin–Radushkevich sorption isotherms were obtained by Sy. pevalekii and Sc. bernardii, for the quantitative description of Co 2 + uptake. All models studied are well suited to describe the Co 2 + isotherm biosorption equilibrium by Sy. pevalekii than by Sc. bernardii. Dubinin–Radushkevich isotherm suggesting that the adsorption mechanism was physical in nature. Sy pevalekii was an efficient to remove Co 2 + ions than Sc. bernardii. Nevertheless, affinity constant of Co 2 + for Sc. bernardii was higher than that of Sy. pevalekii, revealing that Sc. bernardii is more sensitive to Co 2 + ion toxicity than Sy. pevalekii. FTIR study of algae before and after biosorption showed the presence of groups of amide, alkyl, hydroxyl, carbonyl and carboxyl responsible for Co 2 + ions biosorption. This indicates that Sy. pevalekii and Sc. bernardii can be used as a biosorbent for removing heavy metals from various contaminated sites.

Trends in Carbon Dioxide (CO2) Fixation by Microbial Cultivations

Biological route is one of the viable options to mitigate CO2 from its point sources. The major purpose of the review article is to discuss the possible utilization of microbial cultures for the mitigation of CO2. The article also highlights the scaling-up approach for biological processes especially when microbial cultures are utilized for the same. Few recent studies reported the chemoautotrophic fixation of CO2(g) by catalyzing thermodynamically favored but kinetically inhibited oxidation-reduction or electron donor-acceptor scheme of dissolved inorganic compounds. The previous studies have confirmed the utilization of different bacterial strains for the mitigation of 5%, 10%, and 15% CO2(g) in the absence of light and its simultaneous conversion into valuable products in the lab scale bioreactor. The recent studies also revealed the possibility of prokaryotes to assimilate CO2(g) via carbon concentration mechanism (CCM). The article summarizes the biological route for the natural assimilation of CO2(g) into biomass at the expense of very less energy penalty, via photoautotrophy and chemolithotrophy. The chemolithotrophs utilizes different concentrations of CO2 and thiosulfate salts as an energy source for the non-photosynthetic process. The identification of products using Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectroscopy (GCMS) studies is also entailed. The concept of material balance approach is explained to established the mechanism of CO2(g) mitigation through bacterial route. The obtained results pave the way for further development of CO2 utilization technology at larger scales.

The role of CO2 dilution on soot formation and combustion characteristics in counter-flow diffusion flames of ethylene

The effect on soot formation of carbon dioxide addition as diluent in ethylene/O2/Ar laminar counter flow diffusion flames has been examined both experimentally and with the help of a multi-sectional kinetic model. Different concentrations of CO2 have been used in the oxidizer stream to replace argon, whereas the amount of oxygen has been kept constant. Optical techniques have been adopted to measure particulate matter: laser-induced fluorescence (LIF) to detect carbon nanoparticles and laser-induced incandescence (LII) to detect soot. Significant reductions of both soot and carbon nanoparticles have been observed with the addition of CO2: by increasing the amount of CO2, the reduction of particulate matter increases. In the case of 100% CO2 as diluent, soot particles are completely depleted, whereas carbon nanoparticles are still formed but at a lower rate. Therefore, the net result of CO2 addition is the reduced emission of total particulate matter enriched in carbon nanoparticles. On the basis of the results of the kinetic model, particle reduction has been mostly attributed to a thermal effect due to the reduced adiabatic flame temperatures at increasing amounts of CO2 added and only partially to the chemical effect of CO2 in enhancing OH radical formation.

Fluids in High-Pressure Granulites

Properties of fluids in high-pressure granulites were studied in HP granulites (~8.7–11 kbar, ~800–900°С) and syngranulite fluid infiltration-driven HP metasomatites (~11–9 kbar, ~920–850°С) from the Lapland granulite belt of the Fennoscandian Shield. The study involved large-scale mapping of the rocks, microthermometry of mineral-hosted fluid inclusions, multiequilibrium mineral thermobarometry, and calculations of H2O activity based on mineral equilibria. The mafic pyroxene granulites and syngranulite metasomatites (quartz blastomylonites with orthopyroxene, sillimanite, and garnet; veins and vein-like bodies of orthopyroxene–garnet and diopside–scapolite rocks) contain similar assemblages of syngenetic fluid inclusions (which are hosted mostly in quartz and also in garnet, orthopyroxene, and scapolite) of contrasting chemical composition: nearly pure СО2 (distinctly predominant), brines (the dominant salts are CaCl2 and NaCl), and N2 ± H2O. These three types of inclusions coexist in the same generations of early inclusions: rarer primary (p) and predominant primary–secondary (ps). The CO2 inclusions have either high or low densities, and the N2 inclusions are of low density. The brine inclusions show a wide range of total salt contents (up to 30–35 wt%) and variable concentration proportions of the dominant salts: p-inclusions with a salinity of 20 wt% CaCl2 + 10 wt% NaCl; ps-inclusions with a salinity of 5 wt% CaCl2 + 20 wt% NaCl; p- and ps-inclusions with a salinity of 5–23 wt% NaCl eq; and p-inclusions with halite (up to 35 wt% NaCl). In general, CaCl2 is the predominant salt component in the early p- and ps-inclusions of the rocks. Considered together, currently available data (including Sr, Nd, and O isotope systems) on these rocks indicate that the external fluid flow during the origin of granulites was evidently of mantle origin. At the peak P–T parameters, the inclusions were entrapped from a heterogeneous fluid in which immiscible water–salt and CO2-rich fluids, which initially contained N2, coexisted. Data on the chemical composition and salt concentrations of the fluids, $${{a}_{{{{{\text{H}}}_{2}}{\text{O}}}}}$$ = 0.40–0.51, are compared with the theoretically predicted phase state of the fluids and the properties of the coexisting immiscible fluid phases at the estimated P–T parameters of granulite petrogenesis on the basis of numerical models in the H2O–CO2–NaCl and H2O–CO2–CaCl2 ternary systems. The location of the tie-lines and solvus were calculated to subsequently use for the thermodynamic prediction. The paper discusses similarity and the reasons for the difference between the theoretical compositions of the generated fluid phases and the composition of fluid inclusions, geochemical consequences of the heterogenization of granulite fluids (the formation of concentrated alkaline brines and a potentially acidic CO2-rich fluid phase, the values of the mass and volume fractions of these phases depending on variations in the composition of the initial homogeneous fluid, etc.). It follows that an extensive region of the compositions of aqueous fluids with different concentrations of CO2 and Na and Ca chlorides exists at the P–T parameters of HP granulites in which originally homogeneous fluid splits into compositionally contrasting fluid phases with different properties. This region of coexisting immiscible fluids significantly expands with increasing CaCl2 concentration. Hence, the lower crust at the level of the HP granulite facies may be the region where high-temperature immiscible fluids are generated. One of these fluids is a denser phase of alkaline brines, and the other is a less dense potentially acidic phase of H2O–CO2 fluids rich in CO2. Ascending along regional permeable zones, these fluid phases of deep origin can play an important role in magmatic, metamorphic, metasomatic, and ore-forming processes in the middle and upper crust.