• International Journal of Automotive Technology
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• v.6 no.6
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• pp.585-590
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• 2005

The effects of spark timing and exhaust valve timing change on exhaust gas temperature during cold start period of an SI engine are studied through engine bench tests. The exhaust gas temperature increases when the spark timing or valve timing are retarded individually, due to late combustion or slow flame speed. Therefore, exhaust gas temperature shows a large increase when the two timings are retarded simultaneously. However, it is considered that combustion stability during cold start deteriorated under these retarded conditions. To increase exhaust gas temperature for fast warmup of catalysts while maintaining combustion stability, an optimal condition for spark and valve timing retard should be applied for the cold start period.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.10
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• pp.855-859
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• 2007

Hydrogen as an energy carrier in fuel cell offers perhaps the largest potential benefits of reduced emissions of pollutants and greenhouse gases. The generation of high-purity hydrogen from hydrocarbon fuels is essential for efficient operation of fuel cell. Reduction of carbon monoxide to an acceptable level of 10ppm involves high temperature and low temperature water gas shift (WGS), followed by selective oxidation of residual carbon monoxide. The WGS reactor was designed and tested in this study to produce hydrogen-rich gas with CO to less than 5000 ppm. In the water gas shift operation, gas emerges from the reformer is taken through a high temperature shift (HTS) catalyst to reduce the CO concentration to about $2{\sim}4%$ followed to about 5000 ppm via a low temperature shift (LTS) catalyst.

• Journal of ILASS-Korea
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• v.9 no.1
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• pp.15-20
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• 2004

The post injection effect to enhance aftertreatment devices' performance is essential to meet future stringent emission standards by controlling exhaust gas temperature and emission pollutants. The test has been made with commercial common rail diesel engine by post injection manipulation, to optimize exhaust gas temperature while guarantee low fuel penalty. The optimization was done at 1500, 2000 and 2500[rpm] for 2, 4[bar] condition which show low exhaust gas temperature. The main purpose of this test is dedicated to understand mechanism of exhaust gas temperature rise while optimizing

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.3 s.234
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• pp.384-389
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• 2005

Experimental study of variation of exhaust gas temperature was carried out with the changes of spark timing and exhaust valve timing during the cold start operation of an SI engine. To investigate the effects of these variables on combustion stability, cylinder pressure and exhaust gas temperature were measured and analyzed. Experimental results showed that exhaust gas temperature increased when spark and exhaust valve timings were retarded from the baseline cases. However, combustion stability during cold start deteriorated under the retarded conditions. To increase exhaust gas temperature for fast warmup of catalysts while maintaining combustion stability, an optimal condition for spark and valve timing retard should be appied for the cold start period.

• Journal of Sensor Science and Technology
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• v.26 no.3
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• pp.168-172
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• 2017

A nondispersive infrared (NDIR) ethanol gas sensor was prototyped with ASIC implemented thermopile sensor, which included a temperature sensor and two ellipsoidal waveguide structures. The temperature dependency of the two ethanol sensors (with partially blocked and intact structures) has been characterized. The two ethanol gas sensors showed linear output voltages initially when varying the ambient temperature from 253 K to 333 K. The slope of the temperature sensor presented a constant value of 15 mV/K. After temperature compensation, the ethanol gas sensor estimated ethanol concentrations with larger errors of 20 to 25% below 200 ppm. However, the estimation errors were reduced to between -10 and +1 % from 253 K to 333 K above 200 ppm ethanol gas concentration in this research.

• Journal of Energy Engineering
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• v.16 no.1 s.49
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• pp.1-6
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• 2007

The purpose of this study was to investigate the reduction of exhaust gas temperature in a LPG engine that had been converted from a diesel engine. A conventional diesel engine was modified to a LPG (Liquefied Petroleum Gas) engine by replacing the diesel fuel injection pump with a LPG fuel system. The research was performed by measuring the exhaust gas temperature upon varying spark ignition timing, airfuel ratio, compression ratio, and different compositions of butane and propane. Engine power and exhaust temperature were not influenced by various butane/propane fuel compositions. Finally, among the parameters studied in this investigation, spark ignition timing is one of the most important in reducing exhaust gas temperature.

• 연구논문집
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• s.29
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• pp.5-15
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• 1999

Present study deals with performance analysis of an inert gas generator (IGG) which is to be used as an effective mean to suppress the fire. The IGG uses a turbo jet cycle gas turbine engine to generate inert gas for fire extinguishing. It is generally known that a lesser degree of oxygen content in the product of combustion will increase the effectiveness of fire suppressing. An inert gas generator system with water injection will bring advantages of suffocating and cooling effects which are considered as vital factors for fire extinguishing. As the inert gas is injected to the burning site, it lowers the oxygen content of the air surrounding the flame as well as reduces the temperature around the fire as the vapour in the inert gas evaporates during the time of spreading. Some important aspects of influencing parameters, such as, air excess coefficient. $\alpha$, compressor pressure ratio, $ pi_c$, air temperature before combustion chamber, $T_2$, gas temperature after combustion chamber, $T_3$, mass flow rate of water injection, $M_w$, etc., on the performance of IGG system are investigated. Calculations of total amount of water needed to reduce the turbine exit temperature to pre-set nozzle exit temperature employing a heat exchanger were made to compare the economics of the system. A heat exchanger with two step cooling by water and steam is considered to be better than water cooling only. Computer programs were developed to perform the cycle analysis of the IGG system and heat exchanger considered in the present study.

• Nuclear Engineering and Technology
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• v.55 no.2
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• pp.780-791
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• 2023

To study oscillation characteristic of steam and non-condensable gas direct contact condensation through multi-hole sparger at low mass flux, a series of experiments of pure steam and mixture gas condensation have been carried out under the conditions of steam mass flux of 20-120kg/m²s, water temperature of 20-95 ℃ and mass fraction of non-condensable gas of 0-5%. The regime map of pure steam condensation through multi-hole sparger is divided into steam chugging, separated bubble, aggregated bubble and escaping aggregated bubble. The bubbles behavior of synchronization in the same hole columns and desynchronized excitation between different hole columns can be found. The coalescence effect of mixture bubbles increases with water temperature and non-condensable gas content increasing. Pressure oscillation intensity of pure steam condensation first increases and then decreases with water temperature increasing, and increases with steam mass flux increasing. Pressure oscillation intensity of mixture gas condensation decreases with water temperature and non-condensable gas content increasing, which is significantly weaker than that of pure steam condensation. The oscillation dominant frequency decreases with the rise of water temperature and non-condensable gas content. The correlations for oscillation intensity and dominant frequency respectively are developed in pure steam and mixture gas condensation at low mass flux.

• Transactions of the Korean Society of Mechanical Engineers
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• v.3 no.4
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• pp.173-180
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• 1979

Temperature distriburion in a hollow chlinder has been analyzed mathematically. Unsteady condition considered assumed a constant heat flux input from the inside. The results are compared with experimental results of surface temperature rise of a gun barrel during continuous firing. Their agreements are acceptable. Effects of various dimensionless parameters on the surface temperature rise are discussed. For small Biot numbers, the external survface temperature approaches more rapidly to the steady temperature. Temperature difference between internal and external surfaces becomes greater for small Biot number. Steady solution assumed that the gas temperature inside the cylinder varies periodically. Relative amplitude and phase angles between the gas temperature and the internal or external surface temperature are obtained. Phase angles become smaller for large radiancy of gas temperature variation, small external Biot number, or large internal biot number. Relative amplitudes become samller as radiancy of gas temperature variation and internal Biot number become smaller. or external Biot number becomes larger. The solution obtained in this paper can be applied to gun barrels, heat pipes used in heat excangers, and reciprocation engines.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.1
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• pp.114-122
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• 1994

A cold temperature control system for the BAF(batch annealing furnace) has been established in order to reduce energy consumption to imrpove productivity and stabilize the properties of products. Therefore we confirmed a relation between annealing cycle time and atmospheric gas, changing annealing cycle time according to BAF temperature with time during heating and actual temperature measurements cold spot during soaking. The results of the temperature variation effect on the batch annealing are as follows. 1) Cooling rate is increasing gradually with increasing atmospheric gas flow, but heating rate is hardly increasing without atmospheric gas component. Heating time is reduced to one half with increasing atmospheric gas flow rate and changing of atmospheric gas component from HNx to Ax gas and annealing cycle time is reduce to 2.7 times. 2) With enlarging the difference between furnace temperature and soaking temperature at the HNx BAF, heating time becomes short, but cooling time is indifferent. 3) If temperature difference of 300.deg. C in the temperature change of cold spot according to the annealing cycle control temperature, Hi-CON/H2BAF is interchanging at each other at 26hours, but HNxBAF at 50 hours. 4) Soaking time at batch annealing cycle determination is made a decision by the input coil width, and soaking time for quality homogenization of 1219 mm width coil must be 2.5 hours longer then that of 914mm width coil for the same coil weight at Hi-CON/H2BAF. But, it is necessary to make 2 hours longer at HNxBAF.