• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.117-119
• /
• 2017

The multi-stage catalytic igniter for hybrid rocket auto ignition is described in this paper. After charging the catalyst and pre-heating the first stage, the $N_2O$ was supplied at the first stage with the low mass flow rate, and then the $N_2O$ with the high flow rate was supplied into the second stage. Even though the $N_2O$ flow rate was high, it was decomposed by supplying the high temperature gas which was evolved from the $N_2O$ decomposition in the first stage. This multi-stage ignitor resulted in the decrease of the ignition time in comparison with the previous ignitor, and confirmed the possibility of $N_2O$ decomposition with the high flow rate using the multi-stage catalytic-ignition system.

• Proceedings of the KSME Conference
• /
• 2000.11b
• /
• pp.335-340
• /
• 2000

Most vehicle's exhaust emissions come from the cold transient period of the FTP-75 test. In this study, UEGI technology was developed to help close-coupled catalytic converter (CCC) reach light-off temperature within a few seconds after cold-start. In the UEGI system, unburned exhaust mixture is ignited by four glow plugs installed upstream of the catalyst. Experimental results showed that the temperature of CCC rises faster with the UEGI technology, and the CCC reaches light-off temperature earlier. Under the conditions tested, the light-off time of the baseline case was 62 seconds and that of the UEGI case was 33 seconds.

• Journal of the Korean Society of Combustion
• /
• v.10 no.1
• /
• pp.20-26
• /
• 2005

In the present study, catalytic combustion of hydrogen-air premixture in a millimeter scale monolith coated with Pt catalyst was investigated. As the combustor size decreases, the heat loss increases in proportion with the inverse of the scale of combustion chamber and combustion efficiency decreases in a conventional type of combustor. Combustion reaction assisted by catalyst can reduce the heat loss by decreasing the reaction temperature at which catalytic conversion takes place. Another advantage of catalytic combustion is that ignition is not required. Platinum was coated by incipient wetness method on a millimeter scale monolith with cell size of $1{\times}1mm$. Using this monolith as the core of the reaction chamber, temperatures were recorded at various locations along the flow direction. Burnt gas was passed to a gas chromatography system to measure the hydrogen content after the reaction. The measurements were made at various volume flow rate of the fuel-air premixture. The gas chromatography results showed the reaction was complete at all the test conditions and the reacting species penetrated the laminar boundary layer at the honeycomb and made contact with the catalyst coated surface. At all the measuring locations, the record showed monotonous increase of temperature during the measurement duration. And the temperature profile showed that the peak temperature is reached at the point nearest to the gas inlet and decreasing temperature along the flow direction.

• International Journal of Automotive Technology
• /
• v.6 no.5
• /
• pp.445-451
• /
• 2005

Most of the pollutants from passenger cars are emitted during the cold-transient phase of the FTP-75 test. In order to reduce the exhaust emissions during the cold-transient period, it is essential to warm up the catalyst as fast as possible after the engine starts, and the Unburned Exhaust Gas Ignition (UEGI) technology was developed through our previous studies to help close-coupled catalytic converters (CCC) reach the light-off temperature within a few seconds after cold-start. The UEGI system operates by igniting the unburned exhaust mixture by glow plugs installed upstream of the catalyst. The flame generates a high amount of heat, and if the heat is concentrated on a specific area of monolith surface, then thermal crack or failure of the monolith could occur. Therefore, it is very important to monitor the temperature distribution in the CCC during the UEGI operation, so the local temperatures in the monolith were measured using thermocouples. Experimental results showed that the temperature of CCC rises faster with the UEGI technology, and the CCC reaches the light-off temperature earlier than the baseline case. Under the conditions tested, the light-off time of the baseline case was 62 seconds, compared with 33 seconds for the UEGI case. The peak temperature is well under the thermal melting condition, and temperature distribution is not so severe as to consider thermal stress. It is noted that the UEGI technology is an effective method to warm up the catalyst with a small amount of thermal stress during the cold start period.

• 한국연소학회:학술대회논문집
• /
• 2002.11a
• /
• pp.237-240
• /
• 2002

Micro catalytic reactors are alternative propulsion device that can be used on a nano satellite. When used with a monopropellant, $H_2O_2$, a micro catalytic reactor needs only one supply system as the monopropellant reacts spontaneously on contact with catalyst and releases heat without external ignition, while separate supply lines for fuel and oxidizer are needed for a bipropellant rocket engine. Additionally, $H_2O_2$ is in liquid phase at room temperature, eliminating the burden of storage for gaseous fuel and carburetion of liquid fuel. In order to design a micro catalytic reactor, an appropriate catalyst material must be selected. Considering the safety concern in handling the monopropellants and reaction performance of catalyst, we selected hydrogen peroxide at volume concentration of 70% and perovskite redox catalyst of lantanium cobaltate doped with strondium. Perovskite catalysts are known to have superior reactivity in reduction-oxidation chemical processes. In particular, lantanium cobaltate has better performance in chemical reactions involving oxygen atom exchange than other perovskite materials. In the present study, a process to prepare perovskite type catalyst, $La_{0.8}Sr_{0.2}CoO_3$, and measurement of its propellant decomposition performance in a test reactor are described.

• International Journal of Aeronautical and Space Sciences
• /
• v.18 no.3
• /
• pp.512-521
• /
• 2017

This paper reports development process of a university-based sounding rocket using simplified hybrid rocket propulsion system for low-altitude flight application. A hybrid propulsion system was tried to be designed with as few components as possible for more economical, simpler and safer propulsion system, which is essential for the small scale sounding rocket operation as a CanSat carrier. Using blow-down feeding system and catalytic ignition as combustion starter, 250 N class hybrid rocket system was composed of three components: a composite tank, valves, and a thruster. With a composite tank filled with both hydrogen peroxide($H_2O_2$) as an oxidizer and nitrogen gas($N_2$) as a pressurant, the feeding pressure was operated in blowdown mode during thruster operation. The $MnO_2/Al_2O_3$ catalyst was fabricated for propellant decomposition, and ground test of propulsion system showed the almost theoretical temperature of decomposed $H_2O_2$ at the catalyst reactor, indicating sufficient catalyst efficiency for propellant decomposition. Auto-ignition of the high density polyethylene(HDPE) fuel grain successfully occurred by the decomposed $H_2O_2$ product without additional installation of any ignition devices. Performance test result was well matched with numerical internal ballistics conducted prior to the experimental propulsion system ground test. A sounding rocket using the developed hybrid rocket was designed, fabricated, flight simulated and launch tested. Six degree-of-freedom trajectory estimation code was developed and the comparison result between expected and experimental trajectory validated the accuracy of the developed trajectory estimation code. The fabricated sounding rocket was successfully launched showing the effectiveness of the simplified hybrid rocket propulsion system.

• Journal of Advanced Marine Engineering and Technology
• /
• v.25 no.6
• /
• pp.1260-1271
• /
• 2001

The simulation program which predicts the gas behavior in a spark ignition engine has been developed and verified by the comparison with the experimental results foy the MPI engine, naturally aspirated and turbochared engines with a carburettor. First paper describes the calculations of the behavior of gas in the intake and exhaust system. The generalized method of characteristics including friction, heat transfer, area change and entropy gradients was used to analyse the pipe flow The constant-Pressure model was applied for the analysis of the flow through engine valved, and the constant-pressure perfect-mixing model was applied for the flow at manifold junction. The concept of the sudden area change was used for the muffler and catalytic convertor. Fer the plenum chamber in an MPI engine, constant-pressure model and constant-volume model were both examined. Through the comparison of predicted results with experiments, the simulation program was verified by showing good prediction of the behavior of IC engine qualitatively and quantitatively under wide range of operating conditions.

• Proceedings of the KSME Conference
• /
• 2000.11b
• /
• pp.150-155
• /
• 2000

Exhaust emissions from vehicles are the main source of air pollution. Many researchers are trying to find the way of reducing vehicle emissions, especially in the cold transient period of the FTP-75 test. In this study, UEGI (Unburned Exhaust Gas Ignition) technology, warming up the close-coupled catalytic converter (CCC) by igniting the unburned exhaust mixture using two glow plugs installed in the upstream of the catalyst, was developed. It was applied to an exhaust system with a hydrocarbon adsorber to ensure an effective reduction of HC emission during the cold start period. Results showed that the CCC reaches the light-off temperature (LOT) in a shorter time compared with the baseline exhaust system, and HC and CO emissions are reduced significantly during the cold start.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.06a
• /
• pp.353-356
• /
• 2009

A pivotal mechanical balance of plant for 75kW class molten carbonate fuel cells comprise of a catalytic burner and an ejector which has been designed and tested in KEPRI(Korea Electric Power Research Institute). The catalytic burner, which oxidizes residual fuel in the anode tail gas, was operated at several conditions. Some problems arose due to local overheating or auto-ignition, which could limit the catalyst life. The catalytic burner was designed by considering both gas mixing and gas velocity. Test results showed that the temperature distribution is very uniform. In addition, an ejector is a fluid machinery to be utilized for mixing fluids, maintaining vacuum, and transporting them. The ejector is placed at mixing point between the anode off gas and the cathode off gas or the fresh air Several ejectors were designed and tested to form a suction on the fuel tail gas and balance the differential pressures between anode and cathode over a range of operating conditions. The tests showed that the design of the nozzle and throat played an important role in balancing the anode tail and cathode inlet gas pressures. The 75kW MCFC system built in our ejector and catalytic burner was successfully operated from Novembe, 2008 to April, 2009. It recorded the voltage of 104V at the current of 754A and reached the maximum generating power of 78.5kW DC. The results for both stand-alone and integration into another balance of plant are discussed.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.9
• /
• pp.89-96
• /
• 2006

In this study, fluid flow and thermal characteristics in a catalyst bed for nitrous oxide catalytic decomposition which is introduced as a hybrid rocket ignition system for small satellites were theoretically considered. To analyze the thermal phenomena of the catalyst bed, a so-called porous medium approach has been opted for modeling the honeycomb geometry of the catalyst bed. Using a Brinkman-extended Darcy model for fluid flow and the one-equation model for heat transfer, the analytical solutions for both velocity and temperature distributions in the catalyst bed are obtained and compared with experimental data to validate the porous medium approach. Based on the analytical solutions, parameters of engineering importance are identified to be the porosity of the catalyst bed, effective volumetric ratio, the ratio of the radius of the catalyst bed to the radius of a pore, heat flux generated by a heater, and pumping power. Their effects on thermal phenomena of the catalyst bed are studied.