Gas Heat Source Research Articles

Characterization of the hydrogen plasma in the RF negative ion source by optical emission spectroscopy

Optical emission spectroscopy (OES) is an important noninvasive diagnostic tool for providing insight into the plasmas of the negative ion sources. The plasma spectroscopic characterization of the RF driven negative ion source at Huazhong University of Science and Technology (HUST) is studied with the delivered power from 6 kW to 16 kW. The gas temperature, electron temperature, electron density and the density ratio of atomic hydrogen to molecular hydrogen are extracted from OES. The gas temperature is estimated from the Fulcher band of H2. A global thermal model is developed to investigate the gas heating mechanisms in hydrogen plasmas. The gas temperature calculated by the model using the electron density and electron temperature from OES as input parameters is in good agreement with that from the experiment. The thermal model shows that the dissociation of molecular hydrogen by electron impact is the dominant source of gas heating and that approximately 11% ∼12% of the delivered power is dissipated in gas heating at 0.3 Pa filling pressure. Moreover, the electron temperature, electron density and the ratio of atomic to molecular density are obtained from the absolute intensity of Balmer lines and Fulcher band by using collisional radiative (CR) models of H and H2. The kinetics of the excited states of H are also discussed.

Modification and Optimization of a Baking Oven for Small Scale Bread Production

An existing small-scale single-powered baking oven was modified and optimize into a dual-powered oven. The oven was redesigned to accommodate the initially designed firewood heat source and the newly introduced gas heat source. Four heat exchangers (thermal pipes) were introduced to the baking chamber for effective heat and mass transfer during baking of bread dough. The thermal pipes were made of 2 mm thick hollow galvanized steel pipe of 23 mm diameter and 660 mm length. The performance of the oven was evaluated using the standard performance index, which includes baking capacity, baking efficiency and weight loss of the baked bread. The baked bread’s physical properties were determined and analyzed using Duncan multiple range ANOVA test at significant level of p ˚C, respectively. The physical properties of baked bread, wood-fired were found to correspond with that of gas-fired oven. The modified oven can be used for the baking of dough at domestic, small and medium scale bakery.

Optimization and Evaluation of a Low Temperature Waste Heat Recovery System for a Heavy Duty Engine over a Transient Cycle

<div class="section abstract"><div class="htmlview paragraph">Powertrain efficiency is a critical factor in lowering fuel consumption and reducing the emission of greenhouse gases for an internal combustion engine. One method to increase the powertrain efficiency is to recover some of the wasted heat from the engine using a waste heat recovery system e.g. an organic Rankine cycle. Most waste heat recovery systems in use today for combustion engines use the waste heat from the exhaust gases due to the high temperatures and hence, high energy quality. However, the coolant represents a major source of waste heat in the engine that is mostly overlooked due to its lower temperature. This paper studies the potential of using elevated coolant temperatures in internal combustion engines to improve the viability of low temperature waste heat recovery. The paper first uses engine experiments and multi-linear regression analysis to model the indicated efficiency and recoverable power for a Scania D13 heavy duty engine across a range of engine loads, speeds and coolant temperatures. The recoverable power is obtained from simulations of a dual loop waste heat recovery system using ten working fluids as potential candidates for recovering heat from the exhaust gases and the coolant. The paper then investigates the maximum potential fuel consumption benefit by using elevated coolant temperatures for the Scania engine running on the World Harmonized Transient Cycle. From the simulation results, it was seen that cyclopentane and methanol were the best performing working fluids for the coolant and exhaust gas heat sources respectively. From the analysis on the World Harmonized Transient cycle, when using the best performing working fluids and elevated coolant temperatures, a potential net reduction in fuel consumption of 9% could be obtained.</div></div>

RANCANG BANGUN DAN UJI COBATUNGKU KRUSIBEL DARI TABUNG GAS BEKAS DENGAN MENGGUNAKAN SUMBER PANAS GAS LPG

The availability of crucible furnaces is still limited, so the price in the market is relatively expensive, even though this tool is very important, especially in educational institutions as media for the practice of metal casting. The purpose of this study is to design, build and test the work of a crucible furnace that utilizes used cylinders by using LPG gas heat sources. The design of the furnace uses the autodesk inventor application while the manufacture uses machine tools. Technical data from this crucible furnace is that the body is made from used gas cylinders with an outer diameter of 280 mm, an inner diameter of 140 mm and a height of 490 mm. In the combustion chamber installed a 25.4 mm diameter gas pipeline with a length of 370.5 mm and an air channel diameter of 50.8 mm with a length of 367 mm. Kowi is made of steel with a 110 mm dimension and a height of 280 mm. The results of trials with aluminum smelting show that the crucible furnace is capable of melting 5 kg aluminum for 60 minutes with fuel consumption of 3 kg gas. The maximum temperature that can be reached 1367 oC for 15 minutes by a crucible furnace.Keywords: design, manufacture, furnace trials

Exploring the multiphase medium in MKW 08: from the central active galaxy up to cluster scales

Context. The study of the brightest cluster galaxy (BCG) coronae embedded in noncool core (NCC) galaxy clusters is crucial to understand the BCG’s role in galaxy cluster evolution as well as the activation of the self-regulated cooling and heating mechanism in the central regions of galaxy clusters. Aims. We explore the X-ray properties of the intracluster medium (ICM) of the NCC galaxy cluster MKW 08 and the BCG corona, along with their interface region. With recent and deep archival Chandra observations, we study the BCG corona in detail, and with archival XMM-Newton observations, we investigate the implications of the central active galactic nuclei (AGN) on the BCG. Methods. We carry out imaging and spectral analyses of MKW 08 with archival XMM-Newton and Chandra X-ray observations. Results. Our spectral analysis suggests the presence of a central AGN by a power-law with a photon index of Γ ≃ 1.8 at the core of its BCG. Although the ICM does not exhibit a cluster scale cool core, the BCG manifests itself as a mini cool core characterized by a cooling time as short as 64 Myr at r = 3 kpc centered at the galaxy. The isothermality of the BCG corona seems to favor mechanical feedback from the central AGN as the major source of gas heating. The gas pressure profile of this mini cool core suggests that the BCG coronal gas reaches pressure equilibrium with the hotter and less dense ICM inside an interface of nearly constant pressure, delimited by radii 4 ≤ r ≤ 10 kpc at the galactic center. As revealed by the presence of a metal enriched tail (Z ≃ 0.5–0.9 Z⊙) extending up to 40 kpc, the BCG corona seems to be experiencing ram-pressure stripping by the surrounding ICM and/or interacting with a nearby galaxy, IC 1042.

Thermoelectric Power Generation Using LNG Cold Energy and Flue Gas Heat

In this study, semiconductor thermoelectric power generation technology is applied to an LNG air-heated vaporizer. A new type of finned tube with a thermoelectric generation device is designed and the flue gas from natural gas combustion is introduced as the heat source to improve the power generation performance. The results indicate that a gasification tube with a flue gas heat source gives a gasification process of 2.02m, which is 15.8% of the value obtained with an air-heated gasification tube. In case of the vaporizer with a thermoelectric power generation device, an outside wall temperature of 42 °C ensures that frosting problems do not arise along the entire length. The power generation efficiency in the liquid-phase region and two-phase region is about 3.48%. Compared with the air-heated vaporizer with a thermoelectric power generation device, the length of gasification process for the proposed device decreased by 77.6%, while the total output increased by 3.24 times.

고주파 유도가열된 조선용 강판의 기계적 특성 연구

Due to of high intensity, lower noise and easy controllability of the heat, induction heating system became well known. Induction heating method has been suggested as substitute for the gas heat source and adopted in the automation of curved hull forming system. In this study, an investigation was accomplished to find the effects on the change of material properties when the induction heating was applied on the mild steel plate. Plates were heated using weaving method to get sufficiently heat affected zone and then cooled with water or in the air. The mechanical properties of the heated plate were evaluated. As results, the tensile test, impact test and microstructures satisfied the class rule.

Analysis on Heat Source Operation Scheduling of Coal Fired and Gas Fired Source Co-Heating System

As a kind of clean energy, gas heat source will play more and more important role in the future heating system. However, the research for the heat source optimization and dispatch of coal fired and gas fired source co-heating system is quite few in china. In this paper, the characteristic of coal fired and gas fired source co-heating system is proposed, and formulas and parameter selection method for the typical heat source operation scheduling schemes were given. By taking an actually heating network as an example, procedure and method for some heat source dispatch schemes are provided, and the optimal operating scheme based on technical and economic analysis is given. The method provided in this paper may supply the theoretical basis for operation scheduling of realistic engineering heating network. It is very meaningful for saving energy and improving environment.

PHOTOELECTRIC CHARGING OF DUST GRAINS IN THE ENVIRONMENT OF YOUNG STELLAR OBJECTS

The evolution of disks around Young Stellar Objects (YSOs) is deeply affected by the YSOs ultraviolet (UV) radiation field especially in the 500-1100 \AA\ spectral range. The two dominant processes are; the photo-dissociation of H_2 molecules in the Werner and Lyman bands, and the emission of photo-electrons from dust grains when high energy photons are absorbed. Photo-electrons are an important source of gas heating. Dust grain charging when exposed to various possible UV fields in the YSOs environment is investigated. Numerical simulation of the evolution of photo-electrons in the electric field created by the charged dust grains are carried out to obtain a charging profile. From the simulations it appears that the different spectra produce significant quantitative and qualitative different charging processes. Both the UV background and the Ae-Herbig star radiation field produce a relatively slow charging of dust grains due to the low fraction of sufficiently energetic photons. The radiation field of T Tauri Stars (TTSs) is harder due to the release of magnetic energy in the dense magnetospheric environment. These numerical results have been used to propose a new simple analytical model for grain charging in the atmosphere of protostellar disks around TTSs susceptible to be used in any disk modeling. It has been found that the yield decreases exponentially with the dust charge and that two populations of photoelectrons are produced. The high energy population is susceptible of dissociating the H_2 and ionizing some low ionization potential species, such as the Mg. These results add an additional role to dust on the chemistry of the layers just below the H_2 photoionization front. This photoelectic yield has been applied to a simple evaluation of the dust charge in the atmospheres of accretion disks and a simple evaluation of the dust charge in the atmospheres of accretion disks.

Inhomogeneous rarefaction of the process gas in a direct current magnetron sputtering system

The interactions between energetic particles and the sputter gas in a magnetron sputtering system have strong effects on the growth, structures, and properties of the film. These interactions result in inhomogeneous rarefaction of the gas in the space between target and substrate and affect both the transport of particles towards the substrate and the dynamics of the plasma. A hybrid Monte Carlo and fluid model is developed to simulate three-dimensional (3D) gas rarefaction due to the sputtering of metals in argon, neon, and krypton. The governing equations are solved iteratively in a 3D space with a nonuniform grid (octree). Collision events between the sputtered particles and the process gas are assumed as the dominant source of gas heating; however, the effect of the reflected neutrals is also included in the model. Gas rarefaction profiles have been predicted for different process conditions. Model results compare well with experimental ones. The extent of rarefaction depends on process conditions as well as the thermal conductivity of the gas. Materials with high sputtering yield, such as silver, show more rarefaction at a given cathode current than those with low sputtering yield, such as tungsten and aluminum. A higher sputtering yield means more sputtered atoms, thus more energy and momentum deposited in the gas. For a 75mm target at 300W and 10mTorr, a rarefaction of about 65% is obtained for the sputtering of Al in Ar gas, with the substrate plane located 10cm in front of the target.

3D numerical simulation of gas heating effects in a magnetron sputter deposition system

3D numerical simulation of gas heating in a magnetron sputtering system is performed. Pressure, magnetron power density and location of the substrate plane in front of the target are shown to affect the gas temperature profile. For the pressure range under study, maximum gas temperature is shown to increase with pressure. By increasing the separation between the target and the substrate, the maximum gas temperature is shown to increase up to the point when most of the particles are assumed thermalized. Cu shows more gas heating than does Al due to its higher sputtering yield and energy transfer efficiency. Sputtered particles are shown to be the major source of gas heating.

In situ production of Fe–TiC surface composite coatings by tungsten-inert gas heat source

In the present study, AISI 1045 steel surfaces were alloyed with pre-placed graphite, ferrotitanium and Fe–Cr–B–Si powders by using a tungsten-inert gas (TIG) heat source. The effects of welding parameters and thickness of the pre-placed powder layers on the microstructure and properties of the coatings were also investigated. The results indicated that TiC particles can be obtained by direct metallurgical reaction between ferrotitanium and graphite during the TIG welding process. Most of TiC particles were uniformly distributed in the surface coating. The microhardness showed a gradient variation from the molten boundary to the top surface of the coatings, and it was influenced by the thickness of the pre-placed powder layer and the welding parameters. The surface composite coating exhibited a higher hardness and lower wear rate than that of the substrate due to the formation of TiC carbides.

Photoelectric Heating and [Cii] Cooling of High Galactic Latitude Translucent Clouds

The (2P3/2 -> 2P1/2) transition of singly--ionized carbon, [CII], is the primary coolant of diffuse interstellar gas. We describe observations of [CII] emission towards nine high Galactic latitude translucent molecular clouds, made with the long wavelength spectrometer on board the Infrared Space Observatory. To understand the role of dust grains in processing the interstellar radiation field (ISRF) and heating the gas, we compare the [CII] integrated intensity with the far-infrared (FIR) integrated surface brightness for the 101 sampled lines of sight. We find that [CII] is linearly correlated with FIR, and the average ratio is equal to that measured with the COBE satellite for all high-latitude Milky Way gas. There is a significant decrease that was not detected with COBE in [CII] emissivity at high values of FIR. Our sample splits naturally into two populations depending on the 60um/100um surface brightness ratio, or color: ``warm'' positions and ``cold'' positions. A transition from sources with warm to those with cold 60/100 colors coincides approximately with the transition from constant to decreasing [CII] emissivity. We model the [CII] and far-infrared emission under conditions of thermal equilibrium, using the simplifying assumptions that, in all regions heated by the ISRF, the most important source of gas heating is the photoelectric effect on grains and the most important source of gas cooling is [CII] emission. The model matches the data well. There are no statistically significant differences in the derived values of the ISRF intensity and the photoelectric heating efficiency for warm and cold sources. The observed variations in the [CII] emissivity and the 60/100 colors can be understood entirely in terms of the attenuation and softening of the ISRF by translucent clouds, not changes in dust properties.

Parametric Analysis of the Kalina Cycle

The Kalina Cycle utilizes a mixture of ammonia and water as the working fluid in a vapor power cycle. When the liquid mixture is heated the more volatile ammonia tends to vaporize first and at a lower temperature than does pure water. This property of ammonia-water mixtures makes possible a better match to the enthalpy-temperature curve of a hot gas heat source such as a gas turbine exhaust and also permits circulation of fluids of different composition in different parts of the cycle. Taking advantage of the latter feature, condensation (absorption) can be done at slightly above atmospheric pressure with a low concentration of ammonia, while heat input is at a higher concentration for optimum cycle performance. Computer models have been used to optimize a simplified form of the cycle and to compare results for a more complex version proposed by El-Sayed and Tribus. A method of balancing the cycle was developed and key parameters for optimizing the cycle identified.