A living system, either as a whole or as a subsystem, such as human circulatory system, is always under the integrated nervous and humoral control of the whole body, i.e., in homeostasis. Multiple feedback mechanisms with mutual interactions among systems, organs, and even tissues provide integrated control of the entire body. These control mechanisms have different spatial coverages, from the micro- to macroscale, and different time constants, from nanoseconds to decades. This paper presents our approach using multi-scale computational analysis to understand macroscale as well as macroscale blood flows in human circulatory system.

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In order to clarify the vortex flow behind a pitching/heaving airfoil and the characteristics of dynamic thrust acting on them at low Reynolds number region, we have carried out PIV masurement behind both airfoils and have measured the dynamic thrust acting on them. Increasing the nondimensional velocity in pitching/heaving motion, the thrust producing vortex street is clearly formed behind both airfoils. The averaged dynamic thrust acting on them increased as the nondimensional velocity increased. The hysteresis loops of dynamic thrust acting on a pitching/heaving airfoil had concavity/convexity shape characteristics, respectively. The behaviors of the dynamic thrusts strongly depend on the non-dimensional trailing edge velocity and the non-dimensional heaving velocity. The thrust efficiency of a pitching airfoil increased up to V_p= 0.7 and the maximum thrust efficiency was 0.34. On the other hand, the thrust efficiency of a heaving airfoil increased up to V_h=0.4 and the maximum thrust efficiency was 0.20.

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The present study presents a three-dimensional steady numerical simulation of flow through a model of the bifurcation of the common carotid artery (CCA) into the internal (ICA) and external carotid (ECA) arteries. Flow with large inertia bifurcates at the apex (divider tip) and creates a flow recirculation zone associating with very low wall shear stress (WSS) at the outer wall of the ICA sinus where atherosclerotic plaques are localized. The change of both the CCA-ICA and CCA-ECA bifurcation angle has more effect on the distribution of WSS over the outer wall of the sinus. A larger angle of daughter tubes makes the region of low WSS in the ICA sinus narrower in the flow direction, however, makes the WSS gradient in regions surrounding the ICA sinus steeper for a higher volumetric flow ratio of the ICA : ECA. In contrast to the WSS features, the distribution of the axial flow velocity in the plane of symmetry is not very sensitive to the change in both the bifurcation angle and flow ratio between the ICA and ECA.

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Wet-steam flows through steam-turbine cascades in a multiple stage are numerically simulated. Fundamental equations contain conservation laws of water vapor, water liquid, the number density of nucleus, momentum equations, and the energy equation. The SST turbulence model is employed to predict the eddy viscosity. The classical condensation theory is used for modeling homegeneous and heterogeneous condensatins. These equations are solved by the fourth-order compact MUSCL TVD scheme and LU-SGS scheme. As numerical examples, wet-steam flows through a single cascade channel developed by Bakhtar is calculated and the calculated results are compared with the experiments, and wet-steam flows through turbin cascades in a multi stage developed by Mitsubishi Heavy Industries are calculated assuming steady and unsteady states. Finally, the effect of the wetness in the stages are numerically predicted.

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For design optimization of the furnace water wall of pulverized coal-fired boilers, a thermal-hydraulic analysis code to calculate the flow rate and wall temperature distribution in the water wall has been developed. The code can be applied to complex flow networks for two-phase flow consisting of many tubes and headers for both steady and transient states in the distributed parameter system. The detailed flow conditions at any tube position, such as temperature, quality, velocity, etc. can be calculated stably and quickly by the developed algorithm using a matrix solver. The results of 3-D combustion analysis are used as one of the boundary conditions for this code. The performance of the code was verified using steady and transient states data of temperature distribution in the furnace water wall tubes of actual boilers. The results of both steady and transient states analyses showed good agreement with measured data. The new algorithm decreased the calculation time for steady-state analysis significantly compared with the previous algorithm. For transient-state analysis with a high performance computer, it can calculate tube temperature faster than the real transient time.

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Computational fluid dynamics (CFD) simulation was carried out for an oscillatory flow in a 3-D realistic model of the human central airways, and the effect of airway geometry on the oscillatory flow structure was revealed. The computational model of multi-branching airways was prepared from X-ray CT images. Airway diameter ranges from approx. 2 to 14 mm. The flow in the airway model was simulated using CFD software : Fluent. The resultant flow showed differences compared with that observed in a simplified planar multi-branching model. The inspiratory flow patterns were relatively similar to the patterns observed in a simplified airway model, but the expiratory flow patterns strongly depended on the realistic airway geometry and showed more complicated secondary flow structures. Secondary flow velocities were higher in the realistic airway model than in the simplified airway model in both the inspiratory and expiratory flows. Performing Lagrangian fluid particle tracking, we discussed the convective dispersion due to asymmetric inspiratory and expiratory velocity profiles.

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The specific aim of this work is to develop a new technique to control the vibration of a circular cylinder by utilizing the effect of downstream cylindrical body in cruciform arrangement. In this work, a strip-plate with a width w equal to or smaller than the cylinder diameter d is selected as the downstream body. In this report, results of observation of flow visualization in water tunnel and measurements in wind tunnel for fixed systems are presented. The two longitudinal vortices, the trailing and the necklace vortices which were found to induce vibrations of the upstream cylinder in the cruciform two-circular system, are observed around the crossing of the circular-cylinder/stripplate system. Either of the two longitudinal vortices is observed to shed periodically when w/d is 0.50 or 0.62, depending on the gap-to-diameter ratio s/d. While, periodic shedding of the necklace vortex is not observed when 0.75?s/d?1.0.

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The mechanism of atherosclerosis has not been clarified yet. It is known, however, that the blood flow and the vessel wall stress might have more or less impact on its occurring. In the present study, in order to obtain the information of pulsatile flow in the arterial Y-shape bifurcation, where the atherosclerosis selectively occurs, the PIV (Particle Image Velocimetry) measurement has been carried out for Y-tube solid and elastic models. The results of velocity distributions on the centered plane are described for one pulsatile flow pattern, and the difference of flow patterns between solid and elastic models is discussed. Then the validity of the evaluation of wall shear stress from the velocity distribution is examined in comparison with the measured result and the calculated one obtained by commercial CFD code. In the focused pulsatile flow case, the variation of wall shear stress distribution is clarified, which is expected to be useful as basic data to understand the major impact of flow field in the arterial Y-shape bifurcation.

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The lattice kinetic scheme (LKS) for a binary miscible fluid mixture is a applied to mass transfer analysis of Calcium in concrete. In general, cement paste that is a major component of concrete is a porous medium with three-dimensional complicated geometries. The present concrete structure is determined on the basis of experimental data previously obtained by high-intensity X-Ray Computed Tomography (X-Ray-CT). As for the numerical method, the LKS, which is an improved scheme of the original lattice Boltzmann method (LBM), is employed to save computation memory and to maintain numerical stability. First, an unsteady convection-diffusion problem is calculated and the accuracy of the method and error norms with different lattice resolutions are investigated. Next, the mass transfer problem of Calcium in concrete is simulated. Pressure drops in the concrete are calculated for different Reynolds numbers and compared with the empirical equation based on experimental data. Also, velocity fields and concentration profiles are obtained at a pore scale in the structure with heterogeneous mass diffusivity. These simulations indicate that the present method can be useful for prediction of Calcium leaching in concrete from the microscopic point of view.

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The MPS method is a particle method which approximates motion of continua by discrete dynamics of a finite number of particles. Thus it is relatively easy to simulate complicated phenomena in multiphase flows or fluid-structure interaction. In this study, a micro-dispenser reported in Lindemann et al. (2004) is simulated using the MPS method. This microfluidic device offers a challenging problem of fluid-structure interaction and multiphase flows, where deformation of the elastic tube interacts with fluid flow and droplets are ejected changing the topology of the surfaces. The results are compared with the experiment to investigate applicability of the MPS method to microfluidic devices.

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Compressible transonic flows around a circular cylinder are simulated by the finite difference lattice Boltzmann method using the Arbitrary Lagrangian Eulerian formulation. High speed compressible flow is successively calculated by giving the local equihirium distribution function in Eulerian form and moving the body and grids in Lagrangean manner. By this technique, the Navier-Stokes equations are recovered and the fluid velocity is kept small in the equilibrium distribution functions and the calculation becomes stable. Patterns of compressible waves and expansion waves agree well with experimental results. The Rankine-Hugoniot's relation is also recovered for the shock waves appearing on the lee-side of the cylinder.

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In automobile-exhaust systems, catalytic converters are main components and produce substantial pressure drops, which induce engine-power loss and fuel-consumption rise. On the other hand, catalytic converters are required for the uniformity of flow through a catalytic substrate, which causes uniformity of thermal distribution and high catalytic-conversion efficiency. The purpose of this study is to reduce the pressure losses and to improve the flow distribution simultaneously, under spatial constraints. The authors propose a new type of device and show its performance experimentally. Namely, the authors place a dome as a flow deflector inside the diffuser in front of a catalyst in order to suppress flow separation. The converter tested in the present study has a standard cylindrical ceramic substrate with a circular cross section. As a result, we present the optimum dome geometry that can reduce the pressure loss by 22% as compared to a no-dome converter.

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The three-dimensional flow structure induced by normal shock-wave/boundary-layer interaction in a transonic diffuser is investigated experimentally and computationally. The experiments are done with the wall pressure measurement and oil-flow surface visualization. In the computational work, Reynolds-averaged Navier-Stokes equations are solved numerically with the k-w two-equation turbulence model. The solution reproduces very well the measured streamwise pressure distribution and the vortices observed in the oil-flow visualization. The careful investigation of the calculated flow reveals that the vortices are generated at the foot of the shock wave and bended downstream. It is also found that the boundary layers have a three-dimensional shape downstream of the shock wave. These flow characteristics are explained well with the simple flow model constructed by considering the wave configuration near the diffuser corner.

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The flow in a rotating Pelton bucket is simulated by a Moving-Particle Semi-Implicit Method (MPS). In the MPS method, the solid wall of the bucket has to be represented by the same calculation particles as those for fluid, though a Pelton bucket has complicated 3D shape. Therefore, a simple method arranging the wall particles is introduced. As the first step of MPS simulation, the jet entering the bucket is determined by relative jet paths. The free sheet flow on the rotating bucket is simulated and discharging flow pattern is compared with the photograph taken in the model test.

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An experimented study was carried out to study the mechanism of vortex shedding from separation bubble behind a backward step. The experiment was conducted in a circulating water tunnel, and the test body was a triangular prism. Behind the triangular prism, a horizontal plate was set to adjust the height of the separation point from the horizontal plate. The velocity field was measured by LDV systms and the ensemble averaging technique was used to study the unsteady field about vortex generating region. The visualized images were compared with the vorticity distribution and shear velocity distribution at the same phase of evolution to clarify the mechanism of the vortex shedding from the separation bubble.

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Effects of external turbulence in a free stream on a convective boundary layer over a flat boundary are investigated by means of laboratory experiments using a wind tunnel. Turbulence-generating grid is installed upstream of turbulent boundary layer to generate nearly isotropic, external turbulence. The bottom wall of the test section is heated and thus convective boundary layer with unstable thermal stratification (i.e., negative vertical temperature gradient) is developed. Instantaneous velocities, U and V, and instantaneous temperature T are measured simultaneously using a hot wire anemometry with X-probe and a constant current resistance thermometer. The results show that rms value of velocity fluctuations and Reynolds stress are strongly suppressed by the external grid turbulence as in the isothermal case. In the convective boundary layer, rms value of temperature fluctuation and vertical turbulent heat flux are also strongly suppressed by the grid turbulence. The power spectra of u, v and θ and their cospectra show that almost all scale motions are suppressed by the grid turbulence as in the isothermal case.

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Velocity profiles of concentrated fluid/particle mixtures in tube flows through an abrupt contraction were measured using magnetic resonance imaging (MRI). We used aqueous solutions of carboxymethyl cellulose (CMC) containing suspended particles at high volume fractions as test fluids. The particles used have spherical and slender shapes, respectively. These mixture fluids are opaque because of high concentration of particle. The channel used has a square cross section and an abrupt contraction geometry. As a result, a plug-like velocity profile was observed in the channel flow. Furthermore, we found that the velocity profile depends on the particle shape in the contraction. Spherical particle did not affect the flow field but slender particle caused a concave shape in the velocity profile near the centerline at upstream region of the contraction. This concave profile becomes obvious with increasing of volume fraction of particle. This result is caused by the elongational viscosity distribution of the slender particle suspension at the contraction.

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We have analyzed the time-dependent behaviors of the orientational distributions of a dilute colloidal dispersion composed of the ferromagnetic spherocylinder particles influenced by the external magnetic field. A basic equation is derived for the orientational distributions of the particles in steady two dimensional flow by using the perturbation expansion method. An exact solution of the basic equation is obtained theoretically by considering the inverse matrix composed of the functions for the solvable condition. By using the solution, the relevant statistical quantities for an ensemble of the particles are calculated. It is shown that the steady flow causes a distortion of the orientational distribution and can not bring about the steady state of the distribution without the external magnetic field. However, we find the external magnetic field can not always create the steady state of the distribution. We have derived the condition that the steady state of the distribution is made by the external magnetic field and the steady flow. In order to estimate the response of the particles for the magnetic field, the reference time is obtained from the rate of the convergence to the steady state.

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Heat transfer characteristics near the critical Rayleigh number for the onset of natural convection of horizontal anisotropic porous fluid layer heated from below with thin cylindrical rods inserted with high porosity above 0.822 to unity were studied by an analysis and an experiment. The critical Rayleight number Ra_c and dependence of Nusselt number on the Rayleight number were analysed by linear stability theory and series expansion method on the basis of Darcy flow assumption. Critical Rayleight number, increased with decrease in the porosity, was higher for the experiment than for the analysis but the difference was decreased with decrease in Darcy number. Experimental Nusselt number was considerably decreased with decrease in the porosity near unity although Ra_c is rather same as the case of Benard convection without cylindrical rods. The experimental Nusselt number can be expressed by one correlation curve when Nusselt number is plotted against Ra/Ra_c Darcy number of the present experiment was rather large to satisfy Darcy flow assumption. Experiment shows that Darcy flow assumption will be satisfied for Darcy number ?2×10^-3.

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An optimization method for fin pitch in naturally cooled heat sinks is described. Because the heat sinks for the power units of electric trains are stacked vertically, lower heat sinks heat upper heat sinks. However the fin pitch of conventional heat sinks is optimized as single heat sink without accounting for the influence of the lower heat sinks. Equations to predict heat dissipation and a rise in exhaust air temperature in the heat sinks, along with an optimization method for the fin pitch are presented. These equations were carried out from a developed profile of velocity and temperature between two plates. A valid range of the Rayleigh number for the equations is shown, and the optimizing process for the fin pitch of stacked heat sinks is described. The experimental results of the rise in fin temperature of triple stacked heat sinks are compared with the calculated results. The heat sink with optimized arrangement of fins shows over 10% improvement in performance compared with the conventional heat sink.

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To measure turbulent temperature fields accurately using fine-wire temperature sensors, a reliable response compensation scheme is necessary. In this study, the response-compensation methods we have previously developed, which are comprised of four schemes for estimating the time-constant values in time-or frequency-domain, were evaluated systematically using computer-generated temperature signals based on the 0.63μm platinum-wire measurements. The present numerical evaluation has revealed the robustness of the four schemes to instrumentation noise and appraised the validity of the criteria used in the time-constant estimation schemes. Additionally, it was shown that a notable defect of the frequency-domain response compensation schemes using the fast Fourier transform (FFT), which is caused by strong discontinuity between the both ends of a discrete time-series data, can be rectified using the Rotation-Translation method. The present numerical evaluation will help us improve the reliability of fluctuating temperature measurement of turbulent flows by fine-wire temperature sensors such as cold-wires and thermocouples.

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The effects of humidity on drying kinetics and drying time for convection drying of porous material, taking into account steam condensation onto the material at the early stage of drying, were investigated. Mass and core temperature changes of a sample porous material, spherical red brick, were measured using a test apparatus in which the dry-bulb and wet-bulb temperature of the drying medium could be controlled. These were set at 160-240°C and 44-100°C, respectively. The experimental results showed that the critical moisture content decreased and the amount of steam condensation increased at higher wet-bulb conditions. The time required for drying to less than critical moisture content was much the same under all wet-bulb conditions at higher dry-bulb temperature, regardless of steam condensation. In addition, material mass and core temperature changes and drying time were estimated by numerical calculation using a simple calculation model based on receding evaporation plane model and reverse process model. The results obtained from these calculations were in agreement with the experimental results. Factors which determine drying time, such as amount of steam condensation in the pre-heating period, constant drying rate, critical moisture content and falling drying rate, were summarized, and a prediction method for drying time was proposed on a simple calulation model using the values of these factors.

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Effects of various periodic nanometer structures on friction coefficients and behaviors of lubricate liquid molecules were calculated by the classical molecular dynamics simulations. When the wall distance was constant, a friction coefficient decreased and became constant with pressure increase in liquid region. When the wall distance was less than 1.5 nm, a friction coefficient increased under the same pressure condition. A friction coefficient of a surface with periodic linear nanometer structures was less than that of a surface with random nanometer structures. Furthermore, a friction coefficient had a close relationship with the behaviors of liquid molecule and liquid molecules in the region surrounded with a nanostructure and a wall didn't go out even when the upper wall moved.

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The nanostructured surfaces have attracted much attention owing to its possibility of changing surface wettability as well as the enhancement of interface heat transfer, however, the mechanism has not been clarified yet. In this study, molecular dynamics simulations have been carried out to study the effect of the nanostructures on the wetting characteristics at the solid-liquid interface. The simple Lennard-Jones (L-J) liquid droplet is placed on a solid surface in a shape of molecular-scale unevenness with different height and spacing. The wettability of the solid-liquid interface is examined with evaluating the contact angles at the three-phase interface. The results of the measured contact angles demonstrate that the nanostructures could strengthen the hydrophobic properties for a partial wetting condition, while it is insignificant in a completely wetting case. Furthermore, we compare the results of molecular dynamics (MD) simulations with the classical descriptions and discrepancy among the results is found. A modified description of contact angle in consideration of molecules filling ratio among nanostructures was proposed.

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In the present study, the initiation stage of spontaneous vapor explosions generated by single droplets of molten tin submerged in water has been investigated using a high speed video camera operated with reflected light system. The photographs of the formulating process of vapor film, the process of vapor film disturbance and initiation process of the vapor explosions for different mass of molten tin and different diameter of nozzle were obtained. The results show that partial thermal interaction between tin and water does not bring to vapor explosion with fragmentation, and vapor film locally disappears during the formulation term of vapor film around a hot liquid droplet. Direct contact between hot molten tin surface and water is generated in a consequence. However, the local disappearance of vapor film does not progress and the vapor film is reconstructed. A spontaneous vapor explosion begins to vaper film collapse at the local area of the bottom or edge of the disk-shaped droplet.

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In connection with the recent developments of hydrogen stations for fuel-cell vehiles, deflagrative explosions in hydrogen-air mixtures were studied in field experiments. Latex balloons of 0.15 and 1.4 m³ were used for testing gas mixtures of equivalence ratios 0.7, 1.0, 1.8, 2.0, and 3.0. The flame propagation was recorded by a high-speed camera, and the blast pressures were measured at several locations from the explosion center. A spherical flame expansion inside the balloon induces an increase in the balloon volume, and the flame front ruptures the balloon when it reaches the balloon surface. Typical fireball phenomena were observed for fuel rich mixtures. The overpressures and the positive impulses of the mixtures of equivalence ratios 1.0 and 1.8 were the highest for the gas mixtures tested. Sachs's scaling law was used to compare the obtained overpressures with the results of larger scale experiments of up to about 2 000 m³ reported by other research groups. The scaled overpressure vs. distance plot of the present experimental data agrees well with the data of larger scale experiments. The comparison confirms that the vapor cloud volumes of the present experiments are enough to predict the blast damages on the basis of the blast scaling law.

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This research proposes a study of the leading edge of the methane-air triple flame characteristics. Few experiment results are available for physical examination, so an experimental investigation must be conducted to understand the stability mechanisms in a mixture with a steep concentration gradient. To this end, applying acetone-laser-induced fluorescence (acetone-LIF) is studied for measuring concentration profiles at the leading edge of the flame. The results demonstrate that the lifted height is changed when acetone is added to the mixture. It correlates closely with increasing C₂ radical behind the flame edge. Meanwhile, the OH radical luminous intensity measured with a spectroscope is not changed. Moreover, the burning velocity of methane-acetone-air mixture obtained by the Bunsen burner method remains constant. Therefore, the influence of acetone on burning intensity is small. Acetone LIF can thus be advantageous for measuring the local concentration gradient at the leading edge. The acetone LIF signals can be revised considering the thermal effect using the silicone oil vanishing plane. After temperature correction, the transition of the flammability limit width upstream of the flame at a steep concentration gradient can be observed as clearly as in the recent numerical result.

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In this study, the effect of steam addition on spray combustion characteristics was investigated experimentally. A small scale experimental spray combustor which had a swirl burner was used. Kerosene was used as the fuel. The steam flow rate was changed in the steam addition cases. Two steam addition methods (CASE 1 and CASE 2) were used. In CASE 1, the steam was directly introduced into the fuel spray. In CASE 2, the steam was mixed with air and introduced into the combustor together. The temperature, O₂, CO, CO₂, and NO distributions in the combustor were measured. As a result, the miximum temperature and the high temperature region in the combustion chamber were decreased by steam addition, and therefore thermal NO was effectively reduced. The effect of NO reduction in CASE 1 was larger than that in CASE 2. However, in CASE 2, more steam can be added than in CASE 1 with CO emission kept low.

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Premixed charge compression ignition (PCCI) might be one of the powerful tools to achieve high efficiency and reduction of particulate matter and NO_x emissions simultaneously. However, many researches have encountered serious problems of the difficulty of ignition control, high load operation and minimizing unburned emissions. To solve those issues, the author's intend to optimize this kind of combustion method from the standpoint of the modification of fuel. In particular, the mixed fuel consisting of high volatility fuel is capable of use of early injection timing and has a possibility of controlling the fuel propagation process with early injection timing. Thus, this paper focuses on the effect of injection timing which controls the charge stratification on the combustion characteristics and operating range. A single-cylinder engine has been run with direct-injection PCCI operation. In addition, the effect of ignitability of fuel on them was investigated.

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Unregulated toxic emissions from a DI diesel engine with ultra-high EGR low temperature combustion at 50% and 65% loads were measured by FTIR, and reduction characteristics of both regulated and unregulated emissions with exhaust catalysts were investigated. All the regulated emissions at 50% load were reduced to near zero levels with low temperature diesel combustion and the catalysts. At 65% load, approximately 50% reduction in THC and CO were obtained with the catalysts but they are still high at the point of smokeless and ultra-low NO_x diesel combustion with large rates of cooled EGR. The unregulated emissions increase dramatically with intake oxygen content below 14% due to EGR. These trends correlate very well with those of THC emissions. The catalysts are effective to reduce some unregulated toxic emissions including aldehydes and some unsaturated hydrocarbons. However, aromatics and methane generated from ultra-high EGR low temperature smokeless diesel combustion are hardly reduced with the catalysts, in particular, at higher loads

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In order to utilize palm oil ethyl ester (PEE) as an alternative diesel fuel, the combustion characteristics and exhaust emissions are investigated using a small direct injection diesel engine, and are compared with palm oil methyl ester (PME), rapeseed oil ethyl and methyl esters (REE and RME) and the gas oil. As a result, PEE has lower pour point compared with PME. The thermal efficiency of PEE is almost the same as those of the other test fuels. PEE and PME have lower exhaust emissions compared with the other test fuels. Although CO and smoke emissions of PEE are slightly higher than that of PME, NO_x and HC emissions of PEE are almost the same as that of PME. It is concluded that PEE can be used as an alternative petroleum diesel fuel.

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The effective utilization of low calorific gas produced from solid fuels such as biomass with the gasification technology needs an engine generator with minimum allowable fuel gas requirements. Stirling engines have great advantages for the fuel gas diversity because they are external combustion engines. But there are few experimental reports on the utilization of low calorific gases in Stirling engines. In this research, we conducted two types of unit tests to clarify the effect of the heating value of a gas fuel on the engine performance. One is the non-premix test in which the fuel gas with the rated gas heating value of 13.8-25.6 MJ/Nm³ is supplied only into the fuel gas supply port. And the other is the premix test in which the fuel gas with the gas heating value of 6.3-13.8 MJ/Nm³ is supplied both into the fuel gas supply port and the combustion air supply port to expand the required gas heating value range. In the premix test, we demonstrated that we could decrease the lowest gas heating value down to 6.0 MJ/Nm³. As the results, we could expand the gas heating value range and demonstrated that the rated power output can be obtained within the heating value range of 6.0-25.6 MJ/Nm³ with the elecrical efficiency of about 30%. And we measured the exhaust gas content and observed both NO_x and CO emissions being below about 30 ppm (corrected to 14 vol% O₂) in the same gas heating value range.

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