High-temperature Combustion System Research Articles

연소시스템 화석연료 사용량 저감을 위한 잠열에너지저장 기술동향 연구: Part I 열저장 시장규모와 개발수준, 상변화물질 평가

This paper reports development trends of latent heat energy storage technology, one of thermal energy storage technologies, using phase change materials. Part 1 presents policy plans and market size associated with thermal energy storage, evaluation of phase change materials for target temperature, and derivation of thermo-physical properties. Market demand for latent heat storage is increasing to reduce the use of fossil fuel as a way to improve the efficiency of energy-intensive combustion systems through heat recovery. Accordingly, each government is proposing specific policies for thermal energy storage. Demonstration research is being carried out in Germany and Korea. The temperature range of the heat source generated in the high-temperature combustion system is mainly 100-300℃. For this purpose, applicable phase change materials were evaluated. It can be seen that the use of organic materials such as paraffin and fatty acid and inorganic materials such as salt hydrates is appropriate in the low-mid temperature range between 0-100℃ and that molten salt and mixtures thereof are suitable for latent heat storage in the high temperature range of 100-300℃.

A discrete spectral contributions based statistical narrow-band model for high-temperature combustion systems

In this work, we present a discrete spectral contribution based statistical narrow-band model (DSC-SNB) to solve the radiative transfer of high-temperature combustion systems, which employs a discrete spectral strategy to considerably improve the accuracy of the traditional SNB model. Based on the contribution of different gases to radiation, the DSC-SNB model divides the spectral lines into different groups within the spectral interval based on the low-level transition energies (E“). Treating the Line-by-Line (LBL) approach as the benchmark solution, several inhomogeneous high-temperature H2O-CO2-CO mixture columns are adopted to evaluate the DSC-SNB model. Results show that the DSC-SNB model performance is comparable with the traditional SNB model for isothermal gas mixture columns. The DSC-SNB model exhibits high accuracy under mid-high temperature or pure high temperature without low-temperature wrapping, outperforming the traditional SNB model. These findings could be used to reconstruct the multi-dimensional flame temperature field by building a highly accurate and efficient mathematical model for flame radiation prediction.

Experimental research on the mechanism of chemical energy conversion to light energy under thermal induction

Since the discovery of glare illuminators, considerable efforts have been devoted to achieving a breakthrough of high light intensity on the order of magnitude. In this paper, we prepared strong flash blinding agents for the first time by using aluminum powder, oxidant, and adhesive as the main materials, and tris-(8-hydroxyquinolinato) aluminum (Al2q3), triazoindolizine, or nano zinc oxide, etc. as electronic output brightener after mixing and granulation according to the developed formulation. It was discovered that the luminescence intensity was related to the thermal effect of the substance while the brightener only served as an auxiliary brightening effect to achieve energy non-destructive conversion. With the same formula, the luminescence intensities of glaze agents with ADN and potassium perchlorate as oxidants were slightly higher than that of ammonium perchlorate oxidant; the brightening effect of nano-zinc oxide was slightly higher than those of tris-(8-hydroxyquinolinato) aluminum (Al2q3) and triazoindolizine. The luminescence intensity of the substance with a high thermal effect value was high, but the luminescence time was slightly short. Under identical conditions, the luminescence effect of nano-aluminum powder was obviously better than that of micro-aluminum powder with the highest luminescence intensity of 3.9 × 1010 ~ 1.9 × 1011 cd and the luminescence time of 39 - 48 ms. The effects of shell material and structure and the effect of heat-induced mode on the luminescence intensity were also investigated. The luminescence intensity of the glare agent with a high shell strength was high, but the luminescence time was slightly short. Moreover, the energy level of the brightener is excited under the induction of high temperatures, which leads to a blue shift to promote the chemical reaction of the material in a favorable direction. Finally, the optical radiation of the thermally induced high-temperature combustion system was analyzed from the aspects of thermal effect, combustion temperature, and chemiluminescence effect. A way to improve the optical radiation intensity of a high-temperature combustion system was proposed.

Design and implementation of the fuel supply for the high-temperature combustion system

This article describes the configuration and working principle of the high-temperature combustion system; according to the control requirements which have a wide range and high precision for fuel flow-rate of the high-temperature combustion system, a set of fuel supply system is designed based on the frequency conversion hydraulic technology and electro-hydraulic proportional technique. An automatic control system with the function of field and remote control is carried out to achieve the precise supply of the fuel. The transfer function which describes the dynamic characteristic of the fuel supply system is given and the dynamic matrix control algorithm is employed to realize the high-quality control of fuel flow-rate. The experimental results show that the response time of flow-rate is about 12 s, almost no overshoot, and control accuracy within 1%. Therefore, the designed fuel supply system can meet the requirements of the high-temperature combustion system, and the designed control system has good control performance.

Novel tool for Simultaneous Carbon and Nitrogen Stable Isotope Analyses in Aqueous Samples

The quantitative and isotopic analysis of dissolved matter (e.g. dissolved organic carbon, total dissolved nitrogen, etc.) is of particular importance since this pool is a prime conduit in the cycling of N and C. Studying the two elemental pools simultaneously is of importance, as the transformation and transport processes of N and C are inextricably linked in all biologically mediated systems. Dissolved Carbon concentration and isotopic composition can now be determined routinely through coupling of high temperature combustion (HTC) systems to isotope ratio mass spectrometry (IRMS). However the analysis of δ15N of Total Dissolved Nitrogen is fraught with limitations: low concentration makes lyophilisation followed by EA/IRMS laborious and subject to contamination; wet chemical oxidation-IRMS runs the risk of incomplete conversion and cannot distinguish dissolved N2 from Total Dissolved Nitrogen. Further development of our HTC system lead to the implementation of the δ15N determination which is now coupled into a novel total organic carbon (TOC) analyzing system. An integrated, innovative purge and trap technique (peak focusing) for nitrogen with aluminosilicate adsorber and thermoelectric cooling element based system, in combination with high injection volume (up to 3mL) significantly improves sensitivity. Down to 1ppm and less total nitrogen can be measured with precision of ≤ 0.5‰. To decrease the background caused by physically dissolved nitrogen a new, membrane-based, degasser was designed for online separation of physically dissolved nitrogen. This novel HTC system, “iso TOC cube”, provides an innovative tool with large potential in investigation of biogeochemical carbon and nitrogen cycles.

A novel high-temperature combustion based system for stable isotope analysis of dissolved organic carbon in aqueous samples. I: development and validation.

Traditionally, dissolved organic carbon (DOC) stable isotope analysis (SIA) is performed using either offline sample preparation followed by elemental analyzer/isotope ratio mass spectrometry (EA/IRMS) or a wet chemical oxidation (WCO)-based device coupled to an isotope ratio mass spectrometer. The first method is time-consuming and laborious. The second involves the risks of underestimation of DOC concentration and isotopic fractionation due to incomplete oxidation. The development of an analytical method for accurate and sensitive DOC SIA is described in this study. A high-temperature combustion (HTC) system improves upon traditional methods. A novel total organic carbon (TOC) system, specially designed for SIA, was coupled to an isotope ratio mass spectrometer. An integrated purge and trap technique (peak focusing), flexible injection volume (0.05-3 mL), favorable carrier gas flow, modified ash crucible, new design of combustion tube and optimized drying system were used to achieve the necessary performance. The system can reliably measure concentrations up to 1000 mgC/L. Compounds resistant to oxidation, such as barbituric acid, melamine and humic acid, were analyzed with recovery rates of 100 ± 1% proving complete oxidation. In this initial testing, the δ(13) C values of these compounds were determined with precision and trueness of ≤ 0.2‰ even with 3.5% salinity. Further tests with samples with low DOC concentrations resulted in LOQSIA method values of 0.5 mgC/L and 0.2 mgC/L for LOQSIA instr , considering an accuracy of ± 0.5‰ as acceptable. The novel HTC system coupled to an isotope ratio mass spectrometer resulted in significantly improved sensitivity. The system is suitable for salt-containing liquids and compounds that are resistant to oxidation, and it offers a large concentration range. A second paper (which follows this one in this issue) will present a more comprehensive assessment of the analytical performance with a broad set of solutions and real samples. This highly efficient TOC stable isotopic analyzer will probably open up new possibilities in biogeochemical carbon cycle research.

2D mixture fraction measurements in a high pressure and high temperature combustion system using NO tracer-LIF

Mixture fraction measurements in a jet-in-cross flow configuration at high pressures (15 bar) and temperatures (above 1000 K) were performed using planar laser induced fluorescence of nitric oxide (NO-PLIF) as trace species. The goal was the evaluation of this tracer LIF technique for the characterization of the mixing of fuel and hot exhaust gas in the mixing channel. The fuel (natural gas (NG) or H2/N2/NG mixture) along with the tracer were injected into the crossflow of the exhaust gas and PLIF measurements were performed in different planes. In order to relate the measured NO-LIF signal to fuel concentration and mixture fraction, effects of pressure, temperature and species concentration were taken into account. Numerical calculations and spectroscopic simulations that mimic the experimental conditions were performed to identify excitation schemes that give optimum correlations between the NO-LIF signal and the mixture fraction. The measured NO-PLIF images were transformed into mixture fraction plots using the computed correlations. The paper reports on the experimental challenges encountered during the measurements and the steps taken to overcome those difficulties. Examples of mixture fraction distributions are presented and discussed. The paper concludes with a detailed analysis on the accuracy of the measured mixture fraction values.

Probing the dynamics of polyatomic multichannel elementary reactions by crossed molecular beam experiments with soft electron-ionization mass spectrometric detection

In this Perspective we highlight developments in the field of chemical reaction dynamics. Focus is on the advances recently made in the investigation of the dynamics of elementary multichannel radical-molecule and radical-radical reactions, as they have become possible using an improved crossed molecular beam scattering apparatus with universal electron-ionization mass spectrometric detection and time-of-flight analysis. These improvements consist in the implementation of (a) soft ionization detection by tunable low-energy electrons which has permitted us to reduce interfering signals originating from dissociative ionization processes, usually representing a major complication, (b) different beam crossing-angle set-ups which have permitted us to extend the range of collision energies over which a reaction can be studied, from very low (a few kJ mol(-1), as of interest in astrochemistry or planetary atmospheric chemistry) to quite high energies (several tens of kJ mol(-1), as of interest in high temperature combustion systems), and (c) continuous supersonic sources for producing a wide variety of atomic and molecular radical reactant beams. Exploiting these new features it has become possible to tackle the dynamics of a variety of polyatomic multichannel reactions, such as those occurring in many environments ranging from combustion and plasmas to terrestrial/planetary atmospheres and interstellar clouds. By measuring product angular and velocity distributions, after having suppressed or mitigated, when needed, the problem of dissociative ionization of interfering species (reactants, products, background gases) by soft ionization detection, essentially all primary reaction products can be identified, the dynamics of each reaction channel characterized, and the branching ratios determined as a function of collision energy. In general this information, besides being of fundamental relevance, is required for a predictive description of the chemistry of these environments via computer models. Examples are taken from recent on-going work (partly published) on the reactions of atomic oxygen with acetylene, ethylene and allyl radical, of great importance in combustion. A reaction of relevance in interstellar chemistry, as that of atomic carbon with acetylene, is also discussed briefly. Comparison with theoretical results is made wherever possible, both at the level of electronic structure calculations of the potential energy surfaces and dynamical computations. Recent complementary CMB work as well as kinetic work exploiting soft photo-ionization with synchrotron radiation are noted. The examples illustrated in this article demonstrate that the type of dynamical results now obtainable on polyatomic multichannel radical-molecule and radical-radical reactions might well complement reaction kinetics experiments and hence contribute to bridging the gap between microscopic reaction dynamics and thermal reaction kinetics, enhancing significantly our basic knowledge of chemical reactivity and understanding of the elementary reactions which occur in real-world environments.

A LOW TEMPERATURE CO-FIRED CERAMIC ELECTROLTYIC MICROTHRUSTER

Liquid monopropellant microthrusters utilizing electrolytic ignition were designed, fabricated, and analyzed. Low temperature co-fired ceramic tape technologies were used initially to fabricate microscale burners in order to evaluate the applicability of the technology to high temperature combustion systems. Microscale diffusion flames were stabilized in the burners, and optical spectroscopy measurements were performed to characterize the flame behavior. The low temperature co-fired ceramic tape technologies were then applied to the fabrication of microthrusters. The microthrusters had integrated silver electrodes to enable ignition of hydroxylammonium nitrate-based liquid monopropellants by electrolytic decomposition. The volume of the thruster combustion chamber was 0.82 mm3. The microthruster was successfully ignited, and a thrust output of approximately 200 mN was measured with a voltage input of 45 V. Energy input as small as 1.9 J was achieved for ignition, and ignition delay as short as 224.5 ms was recorded.

A method to measure the isotopic ( 13C) composition of dissolved organic carbon using a high temperature combustion instrument

The stable isotopes of dissolved organic carbon (DOC) are a powerful tool for distinguishing sources and inputs of organic matter in aquatic systems. While several methods exist to perform these analyses, no labs routinely utilize a high temperature combustion (HTC) instrument. Advantages of HTC instruments include rapid analysis, small sample volumes and minimal sample preparation, making them the favored devices for most routine oceanic DOC concentration measurements. We developed a stable carbon DOC method based around an HTC system. This method has the benefit of a simple setup, requiring neither vacuum nor high pressures. The main drawback of the method is a significant blank, requiring careful accounting of all blank sources for accurate isotopic and concentration values. We present here a series of experiments to determine the magnitude, source and isotopic composition of the HTC blank. Over time, the blank is very stable at ∼ 20 ng of carbon with a δ 13C of − 18.1‰ vs. VPDB. The similarity of the isotopic composition of the blank and seawater samples makes corrections relatively minor. The precision of the method was determined by oxidizing organic standards with a wide isotopic and concentration range (− 9‰ to − 39‰; 18 μM to 124 μM). Analysis of seawater samples demonstrates the accuracy for low concentration, high salinity samples. The overall error on the measurement is approximately ± 0.8‰.

An explicit numerical scheme for homogeneous gas-phase high-temperature combustion systems

We introduce a new and very simple explicit numerical method for a system of stiff ordinary differential equations (ODEs) that arises from combustion. The main aim of this paper is to show that, contrary to popular belief, an almost trivial explicit method can solve a small class of large nontrivial stiff systems surprisingly efficiently. The algorithm, which is motivated by the theory of Markov jump processes, is very simple and easy to implement. Various numerical experiments are performed to assess the efficiency of the algorithm. For this the ignition of a stoichiometric mixture of n-decane and air at constant pressure and temperature is calculated using a mechanism containing 1218 species and 4825 reactions. For the considered system at moderate accuracy requirements, the new algorithm exhibits performance several orders of magnitude better than standard explicit methods and in the same order of magnitude as the implicit solver packages DASSL and LSODE. The numerical experiments also indicate that the approximate solution obtained from the new algorithm converges to the exact solution of the ODE. Furthermore, we address limitations of our numerical scheme, such as its restriction to the high-temperature regime and moderate accuracy.

Review Paper: Efficient numerical methods for the solution of stiff initial-value problems and differential algebraic equations

In recent years, after a prolonged period of intense activity, the study of numerical methods for solving stiff initial-value problems for ordinary differential equations and differential algebraic equations has reached a certain maturity. There now exist some excellent codes which are both efficient and reliable for solving these particular classes of problems. In this paper, we sketch some of the main theory which underpins stiff integration methods and we use this to describe, and put into context, some of the best codes currently available. By referencing only codes which have been thoroughly tested and are widely available, our aim is to direct users of numerical software to those codes which they should try initially if faced with the problem of solving ordinary differential equations of this type. An additional feature is that the codes which we propose serve as benchmarks against which any new codes can be evaluated.

A numerical study of flash back of laminar premixed flames in ceramic-foam surface burners

Premixed flames, stabilized near the outflow interface of a ceramic-foam surface burner are sensitive to flash-back into the foam, when applied in high-temperature combustion systems. This instable phenomenon is studied numerically for methane/air flames. The analysis is based on stationary and instationary computations using a 1D numerical model, solving the conservation equations for a premixed flame interacting with a solid phase, taking into account complex chemistry and radiation inside the foam. It is shown that stabilization on top of the foam is impossible for a range of velocities if the radiation temperature of the environment becomes too large. A deeper stabilization induces a large increase in the effective burning velocity and as such a higher convective heat flow. When this convective heat production can not be compensated anymore by the increasing radiative heat loss of the foam to the environment, the flame becomes unstable, leading to instationary heating of the foam and flame movement inside the material. Stabilization plots are presented from which the flash-back regions can be determined.

Automated High-Performance, High-Temperature Combustion Total Organic Carbon Analyzer

A high-temperature combustion (HTC) total organic carbon analyzer, which has significant design improvements over existing systems, was developed. The new injection system directly connects a loop-type autoinjector to the head of the HTC column. This connection facilitates the coupling of an autosampler to the injection system. The entire injection process is closed to the atmosphere, thereby improving the precision and eliminating potential contamination during injection. Injections can be made every 3−5 min, depending on the injection and inorganic carbon sparging modes used. The HTC column was designed without a “cold” zone or dead space at the top. These improvements eliminated the memory (or carry-over) effect, which is a potential problem in some HTC column designs. The HTC column is packed with pure quartz beads instead of a relatively expensive Pt-based catalyst, without loss in the oxidation efficiency, as indicated by 100% recovery for various compounds with different refractory properties and by intercomparison with Pt-based HTC systems. The precision for seawater is ∼±0.6% (RSD) at the 80 μM C level. Typically, greater than 5000 injections of seawater can be made without significant deterioration of column performance. The effects of column temperature and carrier gas flow rate on the oxidation efficiency, sensitivity, and reproducibility are reported. Finally, evidence is presented that suggests that there is a relationship between the refractory nature of pure compounds and the peak width. This potential relationship may be a useful tool for quantifying the refractory nature of organic carbon in natural waters.

Multistage catalytic combustion systems and high temperature combustion systems using SiC

Multistage catalytic combustion systems for commercial applications using noble metal catalyst were investigated at conditions under 1000°C. Also, the high temperature combustion systems using SiC material were investigated at conditions up to 1400°C.

Quantitation of Carbon in Oil Shale Process Wastewaters: Coulometry Coupled with Ultraviolet-Peroxydisulfate and High-Temperature Oxidation

Abstract Wastewaters from the production of synfuels, in particular oil shale retort waters, present several major problems to various instrument configurations designed for carbon analysis. A carbon analyzer was fabricated from commercially available oxidation and detection units. Carbon oxidation occurred in an ultraviolet (UV) photochemical reactor using acid peroxydisulfate; quantitation of the evolved carbon dioxide was accomplished with an automatic coulometric titrator. This new design eliminated the problems of (1) instrument downtime caused by fouling of high-temperature combustion catalysts and corrosion of furnace combustion tubes, (2) limited linear dynamic range and upper detection limit (namely, infrared detection), and (3) frequent detector calibration (namely, infrared and flame ionization detection). The UV-persulfate/coulometric titration carbon analyzer was compared statistically with a high-temperature combustion system that is suitable for use with an ASTM method on the basis of (1) the accuracy and precision of recovery of total dissolved carbon (TDC) and dissolved organic carbon (DOC) for nitrogen heterocycles, which were of primary interest because of their preponderance in oil shale process waters and their reported resistance to certain oxidation methods, and (2) the precision of TDC and DOC determinations for nine oil shale process wastewaters. Several qualitative considerations are discussed for both analyzers, including ease of operation, instrument downtime, and maintenance costs.