High-pressure Section Research Articles

Impact of pipe resistance on performance of supercritical carbon dioxide Brayton cycle system

This study develops a system simulation model based on the megawatt-class supercritical carbon dioxide Brayton cycle unit in Hengshui, China, to examine the effect of pipe section resistance on system performance. The results indicate that increased pressure loss in pipe sections significantly reduces power generation efficiency and power supply efficiency. Specifically, a 100 % increase in pressure loss results in 3.290 % and 4.377 % decreases in power generation efficiency and power supply efficiency, respectively. Moreover, higher pressure loss leads to increased CO2 mass flow rate at design power generation load. When the pressure loss is doubled, it requires a 17.593 % increase in CO2 mass flow rate to achieve the design power. Pressure loss in high-pressure section has minimal impact on system performance, while resistance in low-pressure section significantly affects it. For instance, a 100 % increase in pressure loss from the compressor outlet to the low temperature regenerator inlet causes a 0.37 % decrease in system power supply efficiency, and a similar increase from the high temperature regenerator outlet to the low temperature regenerator inlet leads to a 0.76 % decrease. These findings provide meaningful guidance for component design and piping layout optimization for similar systems.

Investigation of the effect of injection rate shaping on combustion and emissions in heavy-duty diesel engine under steady and transient conditions

The fuel injection rate (ROI) is a crucial factor that affects the combustion and emissions of diesel engines. This study focuses on the injection pressure in a common rail system, which is divided into a high-pressure section and a low-pressure section. A control-oriented ROI shaping (ROIs) model is developed based on the switching strategy between high and low injection pressure. Three types of ROI were generated, namely ROIB (conventional ROI), boot-ROI (low followed by high injection pressure), and anti-boot-ROI (high followed by low injection pressure) respectively. The 1-D and 3-D numerical simulations are conducted to analyze the impact of the shaped ROI on combustion and emissions for steady condition and transient condition. In terms of overall results, boot-ROI shows significant advantage among the three types of ROI. For the steady condition, the boot-ROI was able to increase the IMEP (indicated mean effective pressure) (1.57 bar) at high load conditions with almost unchanged NOx emission. For low load conditions with delayed SOI (start of injection), the exhaust temperature is close to that of the ROIB with a reduction of 0.51 g/kW·h in NOx emissions. For transient condition, the boot-ROI also shows its advantage. It was found to improve the BSFC (brake specific fuel consumption) with almost unchanged NOx emission during load-down process. And in load-up process, the BSFC and soot emission also could be improved with slightly increase in NOx emission through advance of SOI when boot-ROI was adopted. The one-dimensional model using boot-ROI reduces fuel consumption by 2 g/kW·h in experiment with WHTC cycles, with slightly higher soot emission and similar NOx emission.

RETRACTED: Analysis and optimization of thermal power plants: Pinch and exergy methods

The increasing demand for electrical energy and the depletion of fossil fuel reserves have underscored the need for the analysis and optimization of thermal power plants. This research focuses on the analysis and optimization of a combined cycle power plant that utilizes natural gas as its primary fuel. The study employs exergy analysis, pinch analysis, and related concepts to analyze the energy flows and identify inefficiencies within the system. The aims of the research are to determine the overall losses, component efficiencies, and overall efficiency of the combined cycle power plant and to optimize its performance using the atomic orbital search algorithm. The optimization aims to reduce waste and increase the overall efficiency of the power plant. By using these methods and algorithms, the research aims to address the challenges associated with fossil fuel consumption and contribute to the sustainable and efficient production of electrical energy. The overall exergy efficiency of the power plant increased from 68.73% in the design mode to 70.56% after optimization, resulting in a significant improvement in energy utilization and a reduction in exergy losses across the cycle components. In the low-pressure section of the heat recovery steam generator, exergy losses decreased from 2791.3 kW to 1600.67 kW after optimization, while in the high-pressure section, exergy losses reduced from 45,013 kW to 42509.72 kW. These optimizations demonstrate the potential to minimize exergy waste and enhance the overall performance of the power plant.

Optimizing Air Compressor Productivity in Supporting Operational Activities on The Mt Ship. Gamalam

Air compressors are auxiliary machines on board that can produce high pressure air. This research was conducted because the productivity of the air compressor was less than optimal, causing air production and the performance of the air compressor to be less than optimal and disrupting operational activities on the ship. The impact that occurs when air production is reduced in the air compressor, the ship cannot operate according to the contract specified by the company, because the initial start of the main engine or main engine on board requires compressed air. Many factors can cause reduced production of air produced by air compressors, including the lack of performance of the suction valve and exhaust valve on the high pressure section which causes less maximum or longer time for filling air into the air bottle, low flow of the lubrication system on the piston which causes no compression to produce air. This research was carried out with the aim of identifying and analyzing the causes of the lack of performance of the suction and exhaust valves on high pressure sections and low flow of the piston lubrication system which results in less optimal performance of the air compressor when filling into air bottles. The method used in this study uses a qualitative descriptive method using primary and secondary data collection approaches and techniques. The lack of performance of the inlet and exhaust valves can be corrected by cleaning the carbon deposits on the valves and leveling the valve surfaces. The low flow of the lubrication system on the piston can be done by checking the lubricating oil pump, cleaning the lubricating oil filter, changing the lubricating oil periodically according to the instruction manual book, and adding lubricating oil according to the specifications of the air compressor.

Repowering a Coal Power Plant Steam Cycle Using Modular Light-Water Reactor Technology

This article presents the results of a techno-economic analysis of repowering a coal-fired power plant’s steam turbine system to instead accept heat produced by a pressurized water reactor-type small modular nuclear system (PWR SMR). This type of repowering presents a challenge due to the significantly lower steam pressure and temperature produced by the nuclear system. A 460 MW supercritical power unit with steam parameters of 28 MPa/560 °C/580 °C, operated in the Łagisza Power Plant in Poland, was selected for the analysis. After repowering, the turbine system would be fed with saturated steam from the steam generators of the SMRs at a pressure of 7 MPa and a temperature of 285 °C. In total, four options for repowering were analyzed. In all cases, the existing high-pressure section of the turbine was disconnected, and the existing low-pressure stages of the turbine, as well as all auxiliary and outward components (feedwater heaters, pumps, generator, condenser, condenser cooling, etc.), are re-used in their existing configurations, except for a feedwater-heater pump that needs to be replaced. In three cases, the existing intermediate pressure turbine section acts as the high-pressure stage of the repowered system. These cases include repowering without an additional reheater (case A), with an added single-stage reheater (B) and with an added two-stage reheater (C). In the fourth case (D), the existing intermediate pressure section was replaced by a new high-pressure turbine stage suited to the SMR live steam conditions. While all four repowering options are technically possible and may represent an economic advantage compared to a complete greenfield SMR installation, option D with a new high-pressure stage is clearly the best option available, with significant cost savings, leading to a lower levelized cost of electricity (LCOE) and a higher net present value (NPV) and net present value ratio (NPVR) than the greenfield case and all other repowering. For relatively new coal power plants with equipment in good condition, this type of repowering may present a cost optimal near-term pathway.

Fire-suppression performance of high-pressure water mist system inside scaled-down road tunnel section

Fire-suppression performance of high-pressure water mist system inside scaled-down road tunnel section

The low power diesel-generator unit with electronically controlled fuel injection

BACKGROUND: Diesel engines, used in generator units, primarily operate in variable loading conditions. Therefore, their technical and economic performance generally deteriorate when the load decreases. It arises from the diesel engine fuel system feature, where pressure and quantity of the fuel, injected into a cylinder, reduces with the load decreasing. As a result, the injection becomes sluggish, the quality of mixing process and combustion becomes worse.
 AIMS: Improvement of effective indicators of the diesel-generator units with electronically controlled fuel injection.
 METHODS: Adjustment of operation modes of the diesel engine of the electrical power unit carried out with use of electronically controlled Denso solenoid, connected to the high-pressure fuel pump via an adapter.
 RESULTS: Results of the motor testing of the low power diesel-generator unit with electronically controlled fuel feed system are described in the article. The oscillograph charts of valve displacement and solenoid magnet winding current, presented in the article, confirm its operation efficiency. Sharp decrease in boost current at the stage of valve lift can be explained by onset of back EMF. Stable solenoid operation at diesel operation velocity of 30003100 min-1 is achieved by means of boost impulse supply to its winding. The boost impulse is supplied from a voltage upconverter and generated by discharge of preliminary charged booster capacitor.
 CONCLUSIONS: Separated fuel feed adjustment in each high-pressure pump section made possible to reduce intersectional fuel feed irregularity to zero. Significant fuel consumption reduction was revealed with the motor testing of the low power diesel-generator unit with electronically controlled fuel feed system (the reduction reaches 10% on low loading operation modes). As mentioned by authors, transition to electronic control of operation modes of diesel engines of autonomous electrical power units does not require major engine design change only to dismantle a mechanical controller and to set an adapter with electronically controlled bypass valve at a section of the high-pressure fuel pump. Electronic control unit supplies current to the valve. For autonomous electrical power units, transition to this control method can be done in typical repair workshop conditions, and an update of one unit (e.g. the KIPOR KDE19AE3) costs 13 950 rubles. By doing so, one electrical power unit may save up to 1191 liters of fuel and more than 63.96 thousands rubles at a cost of 53.7 rubles per liter.

METHOD OF ORGANIZING TWO-STAGE FUEL INJECTION INTO A DIESEL CYLINDER USING A HYDROMECHANICAL FUEL EQUIPMENT

The use of multiphase injection allows reducing the emission levels with exhaust gases and the noise of diesel engines. This paper proposes to improve the hydromechanical fuel supply system of diesel vehicles by providing the possibility of two-stage fuel supply. This task is solved by high-pressure fuel pump equipment, additionally by high-pressure sections that work to inject fuel for pilot injection. The drive shaft cams of these sections are ahead of the shaft cams of the main sections by 2-10 degrees rotation of the camshaft. In order to check the performance of the proposed two-stage fuel supply system and to confirm the possibility of achieving its stated parameters, calculation studies were performed based on mathematical modeling of hydromechanical processes in this system.
 Calculation studies were carried out using a mathematical model of the high-pressure fuel system of the Ch12/14 research single-cylinder diesel engine. The mathematical model is implemented in the MATLAB programming environment. Test results of calculations according to this mathematical model for the operating mode of the system at a camshaft rotation frequency of 650 min-1 and full fuel supply, the high-pressure system provides two-stage injection with the following indicators: total cyclic fuel supply 64 mm3/cycle, pilot dose - 9 mm3/cycle (which is 16% of the total cyclical supply); the maximum injection pressure is 49 MPa with a maximum pressure of 58 MPa in the over-plunger cavity; the maximum injection pressure of the pilot dose is 14.7 MPa, while the pressure reached in the over-plunger cavity is 26.5 MPa; the duration of the injection of the pilot dose is about 2 degrees rotation of the camshaft, the main one - 4.7 degrees rotation of the camshaft.
 The system also provides two-stage injection in modes according to the load (and speed) characteristics. When the load is reduced from the maximum by 35-40%, it does not affect the maximum injection pressure of the main part of the fuel at all speed modes of the system, after which there is a sharp drop of this parameter to the value of the maximum injection pressure of the pilot. The maximum injection pressure of the pilot dose practically does not depend on the speed mode and lies within 13.5-15 MPa. Since the amount of the pilot dose is not adjustable, it does not depend on the movement of the high-pressure fuel pump rail and is 2 mm3/cycle at a rotation frequency of 450 min-1, 6 mm3/cycle at a rotation frequency of 550 min-1 and 9 mm3/cycle at a rotation frequency of 650 min-1.

Stability analysis of the turbine rotor system with foundation support under impact excitation

Considering the stability changes of the whole steam turbine system with and without shock excitation, based on the combined methods of modeling simulation, multi-point analysis and multi-feature map analysis, the support structure of the whole steam turbine rotor under the action of unbalance and shock excitation is analyzed. Stability changes were analyzed. By analyzing the time-domain waveform, frequency spectrum and axis locus of the model casing, the typical support points of the high-pressure rotor section and the low-pressure rotor section under the sudden shock excitation and unbalanced force, the time-domain waveform, frequency spectrum and axis locus of the axis can be grasped. The influence on the structural stability and vibration characteristics of the steam turbine can provide a reference for the shock resistance design of the whole steam turbine system.

Research on the Application of Foamed Lightweight Concrete (FLC) in the Construction of Highway Soft Soil Foundation Engineering with Buried High-Pressure Gas Pipes

In order to study the feasibility and superiority of foam lightweight concrete (FLC) for existing buried high-pressure gas pipeline section under soft soil roadbed, this paper takes the buried existing high-pressure gas pipeline section under the second phase of the Foqingcong Expressway project as the engineering background, and designs two soft soil roadbed treatment schemes, the pile composite foundation method, and the foam lightweight concrete (FLC). Through bearing capacity and settlement calculations, it was confirmed that FLC is feasible for soft soil roadbeds in the existing buried high-pressure gas pipe section, and the three major aspects of analysis, namely the safety benefits, economic benefits and ecological benefits based on the LCA carbon emission calculation, showed that the FLC soft soil roadbed treatment method can reduce the cost by 12% compared with the pile composite foundation treatment method, which is about 1.07 million RMB, and the carbon emission is reduced by about one third. This is a clear benefit advantage. Finally, the feasibility of FLC for buried high-pressure gas pipe sections under both soft soil roadbeds was further verified by field measurements of settlement and earth pressure, which has broad application prospects.

A Study on the Pore Structure and Fractal Characteristics of Briquettes with Different Compression Loads

In order to study the effects of different compression loads on the pore characteristics of coal, taking remolded coal as the research object, the mercury intrusion method was used to determine the pore structures of the briquettes under the compression loads of 50, 70, 90 and 110 MPa, and the Menger sponge model was used to conduct fractal research on the measured parameters. The results show that the compression load has a significant effect on the pore structure parameters of the briquettes. The hysteresis loop generated by the mercury-intrusion and mercury-extrusion curves of raw coal is small, and the pore connectivity is better. After different loads are applied for briquettes, the hysteresis loop becomes larger, and the pore connectivity becomes worse. From the process of the raw coal to the briquettes loaded at 50 and 70 MPa, the pore-specific surface area reduced from 5.069 m2/g to 1.259 m2/g, the total pore volume increased from 0.0553 cm3/g to 0.1877 cm3/g, and the average pore size increased from 43.6 nm to 596.3 nm. When the compression load reached 70 MPa, the specific surface area, total pore volume, and average pore diameter of briquettes remained basically stable with the change in the compression load. The minipores and visible pores and fissures of raw coal contribute 78% of the pore volume, and the micropores and minipores contribute 99% of the specific surface area. After being pressed into briquettes, the volume of mesopores and macropores increases, the volume of visible pores and fractures decreases and the volume of minipores changes little; additionally, the pore surface area contributed by mesopores and macropores increases, and the pore surface area contributed by micropores decreases, indicating that the effect of compression load on pores of 10–100 nm is not obvious, mainly concentrated in the 100–10,000 nm region. The fractal curve of briquettes is fitted into three sections, which are defined as low-pressure sections 1 and 2 and high-pressure section 3, and the fractal dimensions are D1, D2 and D3 respectively. The fractal dimension D1 of briquettes with different compression loads is close to 2, D2 is close to 3 and D3 is greater than 3. The pore structures of briquettes have obvious fractal characteristics in the low-pressure sections 1 and 2 but do not conform to the fractal law in the high-pressure section. Furthermore, in the micropore stage of briquettes, the measured surface area and volume are both negative, indicating that the mercury intrusion method used to test the pore structure of the loaded briquette is more likely to cause the collapse of and damage to the pores in the micropore (<10 nm) stage.

Energy efficiency and power density analysis of a tube array liquid piston air compressor/expander for compressed air energy storage

To improve the power density and efficiency of compressed air energy storage (CAES), this paper adopts an array-based compression/expansion (C/E) chamber structure, coupling a liquid piston with a tubular heat exchanger to form a new compressor/expander. By providing a heat exchange chamber outside the arrayed C/E chamber, natural convection heat transfer is utilized and heat is absorbed during compression and released during expansion, constituting an advanced isothermal CAES system. For low-pressure (0.8 MPa to 5 MPa) and high-pressure (5 MPa to 31.25 MPa) stages, the effects of tube diameter and flow rate variations on C/E pressure, temperature, power density, and efficiency were analyzed. Results show that by keeping the tube diameter constant and the power density increasing one order of magnitude, the efficiency decreases about 9 %. Keeping the power density constant and reducing the tube diameter to 1/7 increases the efficiency of the low and high-pressure sections by about 16 % and 6.4 % respectively, or keeping the efficiency at 93.4 % and 83.9 %, increasing the power density all by about 50 times. This study provides a new way to improve the efficiency and power density of C/E by reducing the tube diameter of the array chamber for high-pressure and high-efficiency CAES.

Thermodynamics of CMC bladed marine gas turbine-LM 2500: Effect of cycle operating parameters

Recent developments in ceramic-matrix composites and their successful use in combustor liners and shrouds have generated interest among researchers to adopt these materials in rotating gas turbine blades, especially in the first stages of high-pressure turbines where gas temperatures are highest. CMC blades have the potential of being retrofitted to replace superalloy turbine blades in operating gas turbines. In this paper, a comparative study on the thermodynamic performance of a marine gas turbine engine, LM 2500, featuring directionally solidified nickel superalloy blades versus novel CMC blades in the high-pressure turbine sections has been reported. Mathematical modeling of the gas turbine cycle components has been developed and then coded in C++ language. The effects of turbine inlet temperature on thermodynamic efficiencies, coolant mass flow rates, and work ratios on the two systems have been analyzed. Finally, the exergy analysis of the systems’ components has been done to identify the benefits of adopting CMC blades in the LM 2500 system. It has been observed that when compared to the directionally solidified bladed turbine system, the projected first law efficiency of CMC bladed LM 2500 gas turbines can be enhanced over 7% (from 34.17% to 41.21%). The projected work ratio can be improved by over 16% (from 0.49 to 0.57) at the turbine inlet temperature of 1725 K.

Optimal Design of Rocket Turbopump Self-Balance System for Rocket Pump considering operating environment

Rocket turbopump has low-pressure section and high-pressure section within a single system. The pressure distribution generates large axial thrust against the rotor. The rocket turbopump balance piston (BP) has the function to autonomously adjust this axial thrust. The operating mechanism of BP is as follows: (1) the rotor moves axial direction when the axial thrust changes, (2) the cross-sectional area of the orifice at impeller back shroud changes, (3) the pressure loss at the orifice changes, (4) The axial thrust is adjusted. Functional verification of the BP is performed by a turbopump test. Therefore, when design changes are implemented, it is necessary to return the upstream design stage. Rocket turbopump, which require high reliability, must be designed to restrain such return risk. In this study, 1DCAE, which performs functional design in the upstream design stage, and robust design, which reduces the effects of variation that occurs in the operational stage, were used. Robust optimization of BP was performed to find the optimal conditions that can restrain axial motion better than the current situation.

Gas adsorption characteristics in deep marine shale gas reservoirs based on molecular simulation

It is of great significance to clarify the adsorption law of shale gas under in-situ conditions for the development of deep marine shale gas reservoirs. However, temperature and pressure in deep reservoirs are far higher than those in the range of normal experiments, so the adsorption characteristics of shale gas in the high-pressure section have not been revealed. In this paper, we construct a kerogen model which conforms to the adsorption law of real marine shale samples by using molecular simulation technology, and simulate the methane adsorption at high temperature and high pressure (HTHP) under in-situ conditions. The adsorption characteristics of methane at HTHP under the influence of primary water are comprehensively revealed, and a corresponding reliable isothermal adsorption model is established. The results show that the influence of kerogen molecular number must be fully considered in the construction of kerogen model, otherwise large errors will occur. The shale gas adsorption capacity is stable under the influence of temperature and changes more significantly with the pressure. In kerogen with polar functional group water can significantly reduce methane adsorption, especially under high pressure. The research results can provide a theoretical basis for the adsorption gas evaluation for deep marine shale gas reservoirs.

Study on the Effect of Soft and Hard Coal Pore Structure on Gas Adsorption Characteristics

In order to grasp the effect of soft and hard coal pore structure on gas adsorption characteristics, based on fractal geometry theory, low-temperature nitrogen adsorption and constant temperature adsorption test methods are used to test the pore structure characteristics of soft coal and its influence on gas adsorption characteristics. We used box dimension algorithm to measure the fractal dimension and distribution of coal sample microstructure. The research results show that the initial nitrogen adsorption capacity of soft coal is greater than that of hard coal, and the adsorption hysteresis loop of soft coal is more obvious than that of hard coal. And the adsorption curve rises faster in the high relative pressure section. The specific surface area and pore volume of soft coal are larger than those of hard coal. The number of pores is much larger than that of hard coal. In particular, the superposition of the adsorption force field in the micropores and the diffusion in the mesopores enhance the adsorption potential of soft coal. Introducing the concept of adsorption residence time, it is concluded that more adsorption sites on the surface of soft coal make the adsorption and residence time of gas on the surface of soft coal longer. Fractal characteristics of the soft coal surface are more obvious. The saturated adsorption capacity of soft coal and the rate of reaching saturation adsorption are both greater than those of hard coal. The research results of this manuscript will provide a theoretical basis for in-depth analysis of the adsorption/desorption mechanism of coalbed methane in soft coal seams and the formulation of practical coalbed methane control measures.

Thermodynamic Performance and Creep Life Assessment Comparing Hydrogen- and Jet-Fueled Turbofan Aero Engine

There is renewed interest in hydrogen as an alternative fuel for aero engines, due to their perceived environmental and performance benefits compared to jet fuel. This paper presents a cycle, thermal performance, energy and creep life assessment of hydrogen compared with jet fuel, using a turbofan aero engine. The turbofan cycle performance was simulated using a code developed by the authors that allows hydrogen and jet fuel to be selected as fuel input. The exergy assessment uses both conservations of energy and mass and the second law of thermodynamics to understand the impact of the fuels on the exergy destruction, exergy efficiency, waste factor ratio, environmental effect factor and sustainability index for a turbofan aero engine. Finally, the study looks at a top-level creep life assessment on the high-pressure turbine hot section influenced by the fuel heating values. This study shows performance (64% reduced fuel flow rate, better SFC) and more extended blade life (15% increase) benefits using liquefied hydrogen fuel, which corresponds with other literary work on the benefits of LH2 over jet fuel. This paper also highlights some drawbacks of hydrogen fuel based on previous research work, and gives recommendations for future work, aimed at maturing the hydrogen fuel concept in aviation.

Energy-Efficient Cooling and Hydraulic Descaling Systems

Determination of real boundary cooling conditions is a fundamental requirement for numerical models and simulations to optimize and control selected processes in metallurgy. To obtain these boundary conditions, a special method has been developed. The input temperature history of cooling is obtained from experiments. The measured data are then mathematically evaluated. Realistic boundary conditions, as the heat transfer coefficient between hot surface and the coolant, allow optimization of the cooling sections and the design of their configurations. To realize the cooling test, unique laboratory equipment was developed. It allows setting of cooling conditions close to the plant conditions. The paper presents examples of optimization of work roll cooling, examples of design of sections for in-line heat treatment of metals and procedure for designing new high-pressure descaling sections. The methodology proposed by the Heat Transfer and Fluid Flow Laboratory of the Brno University of Technology is typically used to determine the heat-transfer coefficient on the surface of high-temperature material in the applications of heat treatment, cooling of rolls of hot rolling mills, and high- pressure descaling. The methodology enables identifying the effect of nozzle water jets on the heat-transfer coefficient or on removal of high-temperature scale and leads to cooling and descaling optimization for industrial partners.

Design of Diaphragmless Shock Tube and Research on its Normal Temperature Characteristics

Shock wave is an important physical phenomenon in supersonic airflow. The shock tube is an experimental device that generates shock wave. It generates shock wave by generating a pressure difference between its high-pressure section and low-pressure section. Most researchers in the world use diaphragm shock tubes to generate shock wave, such as single diaphragm structure and double diaphragms structure type shock tubes. Although the type of shock tube can generate an incident shock wave with a wide range of Mach numbers, in the process of producing shock wave and breaking film, there will be broken film fragments interfering with the flow field. And every time the researcher needs to replace the diaphragm after the experiment, the efficiency of the experiment is low. In this paper, a diaphragmless shock tube is designed. The high-speed reciprocating motion of two pistons in the high-pressure section is used to replace the process of membrane rupture. And the normal temperature characteristics of the shock tube are researched.

Development of High-Performance Cascade Arc Discharge Device for Applications to Plasma Window

We fabricated a cascade arc discharge source with a channel diameter of 8 mm for application to plasma window as an alternative differential pumping. Helium arc plasmas up to a discharge current of 100 A were generated, and the performance as the plasma window was investigated. The pressure ratio of high-pressure discharge section to low-pressure vacuum side was about 200 at a gas flow rate of 0.05 L/min. In order to characterize the plasma parameters around the anode electrode, vacuum UV and visible emissions of He I were measured. The electron density was determined to be 4 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> for a discharge current 100 A and a gas flow rate of 0.05 L/min, while the electron temperature was 0.11 eV. Moreover, the forbidden transition of He I 2s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> S- <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> P was observed. The effect of radiation trapping of He I Ly-α was studied by the intensity ratio of Lyα to forbidden line and the collisional radiative (CR) model. As a result, it was found that the plasma generated was optically thick with an optical escape factor of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> .