CH4 O2 Research Articles

Time-resolved temperature and O atom measurements in nanosecond pulse discharges in combustible mixtures

The paper presents results of time-resolved rotational temperature measurements, by pure rotational coherent anti-Stokes Raman spectroscopy and absolute O atom number density measurements, by two-photon absorption laser induced fluorescence. The experiments were conducted in nanosecond pulse discharges in H2–O2–Ar and C2H4–O2–Ar mixtures, initially at room temperature, operated at a high pulse repetition rate of 40 kHz, in a plane-to-plane double dielectric barrier geometry at a pressure of 40 Torr. Intensified charge-coupled device images show that O2–Ar and H2–O2–Ar plasmas remain diffuse and volume-filling during the entire burst. Images taken in C2H4–O2–Ar plasma demonstrate significant discharge filamentation and constriction along the center plane and in the corners of the test section. The experimental results demonstrate high accuracy of pure rotational psec CARS for thermometry measurements at low partial pressures of oxygen in nonequilibrium plasmas. The results are compared with kinetic modeling calculations, using two different H2–O2 chemistry and C2H4–O2 chemistry mechanisms. In H2–O2–Ar mixtures, the kinetic modeling predictions are in fairly good agreement with the data, predicting temperature rise and O atom accumulation in long discharge bursts, up to 450 pulses. The results show that adding hydrogen to the mixture results in an additional temperature rise, due to its partial oxidation by radicals generated in the plasma, essentially without chain branching. In C2H4–O2–Ar mixtures, the model consistently underpredicts both temperature and O atom number density. The most likely reason for the difference between the experimental data and model predictions is discharge filamentation developing when ethylene is added to the O2–Ar mixture, at fairly low temperatures.

Kinetics of Ignition and Combustion in the Al–CH4–O2 System

The extensive analysis of chain mechanism development in the Al–CH4–O2 mixture is conducted on the basis of a novel kinetic model taking into account the latest theoretical data on rate constants of elementary reactions. The physical properties of Al-containing compounds, needed for the calculation of their transport coefficients, are estimated with the use of a quantum-chemical approach. It has been shown that the addition of a small amount of aluminum nanoparticles to the methane–oxygen mixture substantially accelerates the chain mechanism and results in the decrease of the ignition delay and the increase of the laminar flame speed. The higher the concentration of Al in the mixture, the greater the effect of combustion enhancement. The principal reactions responsible for this effect are indicated.

Methane partial oxidation over a LaCr0.85Ru0.15O3 catalyst: Characterization, activity tests and kinetic modeling

A new LaCr0.85Ru0.15O3 perovskite-type catalyst for CH4 partial oxidation with a high activity and selectivity for syngas with good thermal stability and resistance against coking has been developed. In this paper, the catalyst preparation method, catalyst characterization, results of catalytic tests in a micro-reactor and kinetic modeling are discussed. A partial incorporation of Ru in the perovskite support has been demonstrated which can be responsible for the reported high activity and stability for this catalyst. Reactivity tests have been carried out at both low and high GHSV regimes (≈1–2×107h−1); for the latter case the CH4–O2 partial oxidation reaction system has been studied at incomplete methane (7–18%) and O2 (20–65%) conversion, as rarely reported in the literature. The variation of temperature (650–850°C) and feed gas composition (in terms of CH4, CO, CO2, H2 and H2O inlet partial pressure) allowed to study the reaction system over a wide range of experimental conditions gaining insight in the reaction mechanism. A kinetic model is proposed where CH4 partial oxidation, H2 and CO oxidation and water–gas shift are used to describe the involved lumped reaction network. External diffusion resistances have been found to be negligible whereas internal diffusion resistances have been accounted for by means of a single particle model able to describe the concentration profiles inside the catalyst pellet. Pre-exponential factors and activation energy values for all reactions have been estimated by means of a least square fitting of the experimental data. It is found that CH4 partial oxidation dominates the first region of the catalyst bed while H2 and CO oxidation become important in the remaining part of the bed.

Enhanced stability of membrane reactor for thermal decomposition of CO2 via porous-dense-porous triple-layer composite membrane

A triple-layer composite membrane with porous-dense-porous structure was proposed to develop a high performance membrane reactor. The triple-layer composite membrane consists of a porous Sr0.7Ba0.3Fe0.9Mo0.1O3−δ (SBFM) layer, a dense 0.5wt% Nb2O5-doped SrCo0.8Fe0.2O3−δ (SCFNb) layer and a porous La0.8Sr0.2MnO3−δ–yttria stabilized zirconia (LSM/YSZ) layer. The porous layers can effectively reduce the corrosion of the reactive atmosphere to the membrane, while the dense layer permeated oxygen effectively. Compared with single layer dense SCFNb membrane reactor, the triple-layer composite membrane reactor can be operated for more than 500h. At the temperature of 900°C, the CO2 conversion can reach 20.58% with the CH4 conversion, CO selectivity and O2 flux being about 84%, 97% and 2.13mL(STP)cm−2min−1, respectively. The porous-dense-porous structure can successfully combine the high oxygen permeation and stability of the membrane reactor.

A NiFeCu alloy anode catalyst for direct-methane solid oxide fuel cells

In this study, a new anode catalyst based on a NiFeCu alloy is investigated for use in direct-methane solid oxide fuel cells (SOFCs). The influence of the conductive copper introduced into the anode catalyst layer on the performance of the SOFCs is systematically studied. The catalytic activity for partial oxidation of methane and coking resistance tests are proposed with various anode catalyst layer materials prepared using different methods, including glycine nitrate process (GNP), physical mixing (PM) and impregnation (IMP). The surface conductivity tests indicate that the conductivities of the NiFe–ZrO2/Cu (PM) and NiFe–ZrO2/Cu (IMP) catalysts are considerably greater than that of NiFe–ZrO2/Cu (GNP), which is consistent with the SEM results. Among the three preparation methods, the cell containing the NiFe–ZrO2/Cu (IMP) catalyst layer performs best on CH4–O2 fuel, especially under reduced temperatures, because the coking resistance should be considered in real fuel cell conditions. The cell containing the NiFe–ZrO2/Cu (IMP) catalyst layer also delivers an excellent operational stability using CH4–O2 fuel for 100 h without any signs of decay. In summary, this work provides new alternative anode catalytic materials to accelerate the commercialization of SOFC technology.

Luminescent rare-earth ions doped Al2O3–Y2O3–SiO2 glass microspheres prepared by flame synthesis

A flame-spraying technique was applied for preparation of undoped and 1mol% Nd- and Er-doped Al2O3–Y2O3–SiO2 (YAS) glasses with 5, 10, 15, and 20mol% of SiO2. The glasses were prepared in the form of microspheres by melting precursor powders synthesized by the Pechini method in CH4–O2 flame, and by quenching micro-droplets of the melt by spraying them with deionized water. Prepared transparent glass microspheres were characterized by optical microscopy, SEM, XRD, DTA, UV–vis–NIR, and fluorescence spectroscopy. The undoped microspheres were amorphous, as confirmed by the X-ray powder diffraction. Addition of silica has negligible effect on glass transition temperature, and the temperature of crystallization, due to high structural similarity of all prepared glasses. UV–vis–NIR/fluorescence spectra showed typical absorption/emission/excitation bands due to the presence of optically active Nd3+ and Er3+ ions in the host glass. The Er3+ doped glasses exhibited the strongest excitation at 378nm, which corresponds to 4I15/2→4G11/2 transition of the Er3+ ion. They exhibited strong green emission at 548nm (4S3/2→4I15/2) and a weak green emission at 525nm (2H11/2→4I15/2). The intensities of emission bands decreased with increasing SiO2 content. The Nd3+ doped glasses exhibit three major emission bands at 905, 1067 and 1340nm, corresponding to the 4F3/2→4I9/2, 4F3/2→4I11/2 and 4F3/2→4I13/2 transitions, respectively, of the Nd3+ activator. The emission intensities were not influenced by the content of SiO2. The wavelength of emitted light was not influenced by the structure of glass.

Catalytic NO–CO–C3H6–O2 reactions over hydrothermally stable Rh-supported ZrP2O7 catalyst

A novel and facile hydrothermal synthetic route for ZrP2O7 from ZrO(OH)2 and H3PO4 has been developed to use this as an active support for Rh catalyst. Temperature-programmed reactions of mixtures of NO, CO, C3H6 and O2 with a stoichiometric A/F ratio (14.6) were investigated over Rh-supported ZrP2O7 catalyst. A lower amount of Rh (0.4 wt.%) loaded to ZrP2O7 exhibited satisfactory light-off at lower temperature (T50% = 312 °C) with a steep rise in conversion efficiency after ageing the catalyst at 900 °C for 25 h in a stream of 10% H2O/air. Rh particle growth was not so significant even after 500 h of ageing at 900 °C in the stream of 10% H2O/air, which is one of the reasons for exhibiting adequate catalytic activity of this catalyst after long-term exposure in H2O/air. Reducibility of Rh oxide was enhanced substantially by this support which is believed to be the key factor for exhibiting good catalytic activity after ageing in an oxidizing environment. This newly developed Rh/ZrP2O7 catalyst with minimum Rh loading, having high thermal stability up to 1200 °C along with outstanding capacity to resist sintering at high temperature, has the potential to serve as a new generation deNOx catalyst.

Effect of Aging Atmosphere on Catalytic Activity for NO–CO–C3H6–O2 Reaction of CeO2-Containing Oxide Supported Pd Catalysts

The catalytic activity for CO, hydrocarbon and NO removal on Al2O3 and CeO2 based oxides supported Pd catalysts were studied under switching of aging condition between air and N2 atmosphere. For CeO2-containing Pd catalysts, the deterioration of catalytic activities by aging in N2 was improved by oxidative treatment. Based on results of XPS and FT-IR measurements, it was presumed that the catalytic activity of Pd catalysts was strongly affected by the adsorbed form of CO on Pd, which occurs owing to a change of the chemical state of Pd.

Promoting Effect of CeO2 on the Catalytic Activity of Rhodium Supported on Y-Stabilized ZrO2 for NO–CO–C3H6–O2 Reactions

Abstract The catalytic activity of Rh supported on Y-stabilized ZrO2 for NO–CO–C3H6–O2 reactions under stoichiometric conditions was improved by the addition of 5 mol % CeO2, whereas an excess amount of CeO2 of more than 10 mol % caused a decrease in the NO reduction activity. The improvement was ascribed to the formation of easily reducible Rh species through interaction with a Ce–Zr solid solution.

Flame Stability of Methane and Syngas Oxy-fuel Steam Flames

Oxy-fuel combustion has been used previously in a wide range of industrial applications. Oxy-combustion is carried out by burning a hydrocarbon fuel with oxygen instead of air. Flames burning in this configuration achieve higher flame temperatures, which present opportunities for significant efficiency improvements and direct capture of CO2 from the exhaust stream. In an effort to better understand and characterize the fundamental flame characteristics of oxy-fuel combustion, this research presents the experimental measurements of flame stability of CH4/O2 and syngas (H2–CO)/O2 flames. Effects of the H2 concentration, fuel composition, exhaust gas recirculation ratio, firing inputs, and burner diameters on the flame stability of these fuels are discussed. Effects of exhaust gas recirculation, i.e., CO2 and H2O (steam) acting as diluents on burner operability, are also presented. The roles of firing input on flame stability are then analyzed. For this study, it was observed that many oxy-flames did not stabilize without exhaust gas recirculation because of their higher burning velocities. In addition, the stability regime of all compositions was observed to decrease as the burner diameter increased. A flashback model is also presented, using the critical velocity gradient (gF) values for CH4–O2–CO2 flames. The scaling relation [gF = c(SL2/α)] for different burner diameters was obtained for various diameter burners. The paper shows that results correlated linearly with a scaling value of c = 0.0174.

A capillary bioreactor to increase methane transfer and oxidation through Taylor flow formation and transfer vector addition

The impact of two strategies to enhance the mass transfer of hydrophobic compounds, Taylor flow (or segmented flow) and the addition of an organic transfer vector (silicone oil), were investigated under abiotic and biotic conditions in a capillary bioreactor. The capillary bioreactor consisted of a capillary column (where Taylor flow was produced in a gas/liquid flow) and a gas–liquid separator at the outlet of the capillary column which was operated as a stirred tank with superficial aeration. It was shown that the system was limited by mass transfer and not by the biological reaction. Taylor flow in the capillary resulted in an increase of up to two orders of magnitude for the volumetric oxygen transfer coefficient (kLa) when compared to the coefficient for the gas–liquid separator, or values previously obtained in other turbulent contactors. The bioconversion rates of methane in the capillary column where found to be significantly higher than for conventional systems. Silicone oil addition increased kLa up to 38% in the gas–liquid separator, but reduced it with 38% in the capillary. Contrary to observations during abiotic kLa determinations, silicone oil addition increased the CH4 removal and O2 consumption by the methanotrophic consortium in both, gas–liquid separator and capillary. Increased gas flow rate gave an 19% increase in methane removal in the capillary bioreactor, an additional increase of 8% was obtained adding 5% of silicone oil at the same flow, while an additional increase of 47% was obtained adding 10% of silicone oil at the same flow with inoculum pre-adapted to transfer vector. The contribution of the capillary channel to the overall methane removal in the system was high considering that the volume of this channel was just 0.64% of the total volume in the bioreactor, indicating a good potential of further optimization of the reactor system.

Critical energy of direct detonation initiation in gaseous fuel–oxygen mixtures

The critical energy of some gaseous fuels and oxygen mixtures at different initial pressure and equivalence ratios are measured based on an experiment system we developed. The determination of direct initiation of detonation is based on the overpressure signal from a pressure transducer. The effective energy responsible for the direct initiation is considered as the first quarter cycle of the current discharge. The effect of initial pressure and equivalence ratio on the critical energy of direct initiation is firstly investigated in some typical gaseous fuel (i.e., C2H2, C2H4, C3H8, H2) and oxygen mixtures. It shows that the relationship between critical energy and initial pressure is inversely exponential and it is ‘U’ shaped between critical energy and equivalence ratio. The study of the effect of different oxygen concentration and argon dilution on the critical energy of stoichiometric acetylene and oxygen is carried out, the results indicate that oxygen concentration significantly affects the critical energy, and the critical energy increases with increasing amount of argon dilution. This study finally quantitatively research on the detonation hazard parameter (DH) of each stoichiometric mixture. The value of DH in increasing order for the mixtures are as following: C2H2–O2, C2H2–O2–50%Ar, C2H4–O2, C2H2–O2–65%Ar, C2H2–O2–70%Ar, C3H8–O2 and H2–O2, the results also indicate the critical energy is different by orders of magnitude if fuels do not belong to the same group.

Effects of CO2 Dilution on Methane Ignition in Moderate or Intense Low-oxygen Dilution (MILD) Combustion: A Numerical Study

Homogeneous mixtures of CH4/air under moderate or intense low-oxygen dilution (MILD) combustion conditions were numerically studied to clarify the fundamental effects of exhaust gas recirculation (EGR), especially CO2 in EGR gases, on ignition characteristics. Specifically, effects of CO2 addition on autoignition delay time were emphasized at temperature between 1200 K and 1600 K for a wide range of the lean-to-rich equivalence ratio (0.2∼2). The results showed that the ignition delay time increased with equivalence ratio or CO2 dilution ratio. Furthermore, ignition delay time was seen to be exponentially related with the reciprocal of initial temperature. Special concern was given to the chemical effects of CO2 on the ignition delay time. The enhancement of ignition delay time with CO2 addition can be mainly ascribed to the decrease of H, O and OH radicals. The predictions of temperature profiles and mole fractions of CO and CO2 were strongly related to the chemical effects of CO2. A single ignition time correlation was obtained in form of Arrhenius-type for the entire range of conditions as a function of temperature, CH4 mole fraction and O2 mole fraction. This correlation could successfully capture the complex behaviors of ignition of CH4/air/CO2 mixture. The results can be applied to MILD combustion as “reference time”, for example, to predict ignition delay time in turbulent reacting flow.

Changes in heat production by sheep of Guirra breed after increase in quantity of barley grain on the diet

The heat production (HP) from CH4 and CO2 production and O2 consumption was determined by the respirometry quotient (RQ) method and by C–N balance measurements (CN method). Twelve dry and none pregnant Guirras sheep were fed with 3 diets consisting in the same quantity of alfalfa hay (2kg/d offered) and increasing quantities of barley grain (150, 300 and 450g/d). The experimental design was completely random with 4 replication by treatment. Fasting HP was determinate in one sheep from each group. Ewes were allocated to individual metabolism cages at thermoneutrality. After 10d of adaptation, feed intake, and total fecal and urine output were recorded daily for each ewe during a 5d period, as well as BW at the beginning and end of the period. Gas exchange measurements were recorded by open-circuit face mask respirometry system. Average HP measured by RQ method was in agreement with the average HP determined by CN method accounting for 395.6 and 393.4kJ/kg0.75BW/d, respectively. The metabolizable energy requirement for maintenance (MEm) was estimated by linear regression at 352.3kJ/kg0.75BW.

Dynamics of CH4 oxidation in landfill biocover soil: Effect of O2/CH4 ratio on CH4 metabolism

The CH4 oxidation dynamics was investigated by observing the CH4 oxidation rates at concentrations (from 1.0 × 104 ppmv to 2.0 × 105 ppmv) mixed with O2 (from 5.0 × 104 ppmv to 7.5 × 105 ppmv). The CH4–O2 dual-substrate model based on Michaelis–Menten equation (Km,CH4 = 1.4 × 105 ppmv; Vmax = 7.6 × 102 μmol kg−1 d−1; Km,O2 = 5.5 × 104 ppmv) was got and agreed well with the experimental data when the initial O2/CH4 ratio reached 3:1, indicating full aerobic CH4 oxidization. Anoxic CH4 oxidation gradually became predominant with decreasing O2/CH4 ratios. The effect of CH4 is more significant than O2, as evidenced by higher slope (0.58 kg−1 d−1) of VCH4−[SCH4] line graph compared with that of VCH4−[SCH4] line graph (0.062 kg−1 d−1). The paper presents the dynamics of CH4 oxidation and proposes that ratio of O2/CH4 need to be considered for their dynamically changing in environmental habitats. The findings provide an important parameter for optimizing the operations of breathing biocover systems.

Modeling ammonia–ammonium aqueous chemistries in the Solar System’s icy bodies

The properties of ammonia and ammonium compounds in cold, subsurface brines are important for understanding the behavior of outer planet icy moons. The FREZCHEM model of aqueous chemistry was primarily designed for cold temperatures and high pressures, but does not contain ammonia and ammonium compounds. We added ammonia and ammonium compounds to FREZCHEM, and explored the role of these chemistries on Enceladus and Titan, mindful of their astrobiological implications. For the new FREZCHEM version, Pitzer parameters, volumetric parameters, and equilibrium constants for the Na–K–NH4–Mg–Ca–Fe(II)–Fe(III)–Al–H–Cl–ClO4–Br–SO4–NO3–OH–HCO3–CO3–CO2–O2–CH4–NH3–Si–H2O system were developed for ammonia and ammonium compounds that cover the temperature range of 173–298K and the pressure range of 1–1000bars. Ammonia solubility was extended to 173K, where NH3·2H2O and NH3·H2O precipitate, which is the lowest temperature in existing FREZCHEM versions. A subsurface “ocean” on Enceladus was simulated at 253K with gas pressures, 1–10bars, and with Na+,Cl-,HCO3-,CO2(g),CH4(g), and NH3(aq) that led to precipitation of ice, NaHCO3, and gas hydrates (CO2·6H2O and CH4·6H2O). The pH on Enceladus (Fig. 10) ranged from 5.74 to 6.76, and water activity, aw, ranged from 0.80 to 0.82, which are relatively favorable for life. A subsurface “ocean” on Titan was simulated with NH4+,Cl-,SO42-,CH4(g), and NH3(aq) over the temperature range of 173–273K that led to precipitation of (NH4)2SO4, ice, CH4·6H2O, and NH4Cl. The CH4 clathrate should float above the brine and is buoyant with respect to H2O ice, so has the potential to be a source of CH4 to replenish what has been photochemically destroyed in Titan’s atmosphere over time. The pH in the Titan simulation (Fig. 11) ranged from 11.24 to 18.03 (latter may not be accurate), and aw ranged from 0.28 to 0.72, which are relatively unfavorable for life as we know it. The Titan simulations, with total pressures of 10, 250, and 1000bars, led to similar depositions, except for ice that failed to form under 1000bars of pressure. In the past, there have been arguments for why Titan, given an early environment similar to Earth, could be a highly favorable body in our Solar System for life. But if Titan oceans are strongly alkaline with high pH whereas Enceladus’ oceans have moderate pH, as simulated, the latter would seem a better environment for life as we know it. But bear in mind, caution must be exercised in quantifying the ammonia/ammonium cases because of the complexities and limitations of these chemistries in the FREZCHEM model.

Comprehensive analysis of combustion enhancement mechanisms in a supersonic flow of CH4–O2 mixture with electric-discharge-activated oxygen molecules

Mechanisms of ignition and combustion enhancement in a supersonic CH4–O2 reactive flow behind an inclined shock wave front are analyzed numerically when chemically active species are produced by electric discharges with different values of reduced electric field. The analysis is carried out based on thermally nonequilibrium kinetic models both for the discharge and for the shock-induced combustion, taking into account the disruption of thermodynamic equilibrium between vibrational and translational degrees of freedom of the reacting molecules and treating the vibrational-electronic-chemistry coupling. It is demonstrated that the presence of electronically excited O2 molecules O2(a 1Δg) and as well as O atoms in oxygen plasma allows one to intensify the chain mechanism of CH4–O2 combustion even if the energy put to O2 molecules in the discharge is sufficiently low. The excitation of O2 molecules to the singlet states O2(a 1Δg) and is more preferable in shortening the induction zone length than the production of O atoms in the course of dissociation of O2 molecules due to electron impact. However, both excitation of O2 molecules to the singlet delta and singlet sigma states and production of O atoms in an electric discharge are much more effective in combustion enhancement than merely heating the mixture.

Iron incorporated Ni–ZrO2 catalysts for electric power generation from methane

On the purpose to perform as functional layer of SOFCs operating on methane fuel, NiFe–ZrO2 alloy catalysts have been synthesized and investigated for methane partial oxidation reactions. Ni4Fe1–ZrO2 shows catalytic activity comparable to that of Ni–ZrO2 and superior to other Fe-containing catalysts. In addition, O2-TPO analysis indicates iron is also prone to coke formation; as a result, most of NiFe–ZrO2 catalysts do not show improved coking resistance than Ni–ZrO2. Anyway, Ni4Fe1–ZrO2 (Ni:Fe = 4:1 by weight) prepared by glycine-nitrate process shows somewhat less carbon deposition than the others. However, Raman spectroscopy demonstrates that the addition of Fe does reduce the graphitization degree of the deposited carbon, suggesting the easier elimination of carbon once it is deposited over the catalyst. Ni4Fe1–ZrO2 has an excellent long-term stability for partial oxidation of methane reaction at 850 °C. A solid oxide fuel cell with conventional nickel cermet anode and Ni4Fe1–ZrO2 functional layer is operated on CH4–O2 gas mixture to yield a peak power density of 1038 mW cm−2 at 850 °C, which is comparable to that of hydrogen fuel. In summary, the Ni4Fe1–ZrO2 catalyst is potential catalyst as functional layer for solid-oxide fuel cells operating on methane fuel.

Structure and Catalytic Properties of Pd/10Al2O3·2B2O3. Effect of Preparation Routes and Additives

Abstract The synthesis route of 10Al2O3·2B2O3 (10A2B) and effect of additives were studied to use this compound as a thermally stable support material for Pd catalysts. The preparation by reverse coprecipitation was found to have a beneficial effect on the BET surface area of 10A2B and thus Pd metal dispersion, compared to other preparation routes via solid-state reaction and hydrolysis of metal alkoxides. The addition of 3 wt % BaO suppressed the sintering of 10A2B and Pd during thermal aging at 900 °C in a stream of air containing 10% H2O. Although direct interactions between Pd and the support material were not detected by EXAFS, the catalytic performance for NO–CO–C3H6–O2–H2O reactions under modulated air-to-fuel ratio (A/F) conditions was strongly influenced by the Ba additive. The activity for NO and C3H6 in a rich region (A/F < 14.6) was especially enhanced in the presence of Ba because of accelerated elemental reactions including NO–CO and NO–C3H6. In situ FT-IR of CO suggested that the Pd electronic state changed by electrostatic effect of Ba additives would activate NO and weaken the self-poisoning effect of C3H6.

Description and function of a mobile open-circuit respirometry system to measure gas exchange in small ruminants

A mobile open-circuit respirometry system was constructed for estimating heat production (HP) in small ruminants from CH4 and CO2 production and O2 consumption by the respiratory quotient (RQ) method. The method was evaluated against HP estimates by C–N balance measurements (CN method). Calibration factors were established injecting N2 into the system. Repetitive and consistent values for the calibration factor were obtained (1.0065±0.01307, n=9), which confirms the absence of leaks and good performance of the whole system. A pilot experiment with 14 Granadina female dry goats was conducted to evaluate the system. The metabolizable energy intake (MEI) was close to ME for maintenance. Average HP measured by RQ method was in agreement with the average HP determined by CN method accounting for 505 and 500kJ/kg0.75 BW/d, respectively. It is concluded that the mobile system was suitable for measuring gas exchange and energy metabolism in small ruminants.