• Transactions of the Korean hydrogen and new energy society
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• v.34 no.1
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• pp.77-82
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• 2023

The fuel cell in fuel cell electric vehicle utilizes oxygen in the atmosphere, which requires the use of an air cleaner system to minimize the intake of harmful pollutants. To estimate the performance of the air cleaner system, the pressure drop between the filter inlet and outlet is used under the rated air flow condition. In this study, the effect of sensor error in this air cleaner testing is experimentally carried out. It is found that the errors of the temperature sensor does not significantly affect the estimation of pressure drop. However, in the case of the pressure sensor, 5% sensor error results in the error of pressure drop estimation by 3%. Therefore, it is recommended that the measurement accuracy of the pressure sensor mounted in test system should be maintained at less than 5%.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.6
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• pp.616-625
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• 2017

Measurements using five real-time particle samplers were compared to measurements using three NRM (National Reference Method system) filter-based samplers(Gravimetric method) at Incheon, Korea, between May and August, 2014. The purpose of this study was to suggest the quality assurance/quality control (QA/QC) method of each instrument for use in a real-time continuous particle sampler to measure the mass of airborne particles with an aerodynamic diameter less than $2.5{\mu}m$ ($PM_{2.5}$). Five real-time particle samplers of BAM1020, FH62C_14, TEOM, PM-711 and SPM-613 were evaluated by comparing its measured 23 hr average $PM_{2.5}$ concentrations with those measured with NRM filter-based samplers simultaneously. The parameters(e.g. Inlet heating condition, Slope factor, Film response, Intercept, Background, Span value) of the real-time samplers were optimized respectively by conducting test performance evaluation during 7 days in field sampling. For example, inlet heating temperature of TEOM sampler controls $35{\sim}40^{\circ}C$ to minimize the fluctuation of the real-time measurement data and background value of BAM1020 is the key factor affecting the accuracy of $PM_{2.5}$ mass concentration. We classified the $PM_{2.5}$ concentration according to relative humidity (80%) to identify water absorbed in aerosols by measuring the ${\beta}$-ray samplers(BAM1020, FH62C_14) and TEOM. ${\beta}$-ray samplers were not strongly affected by relative humidity that the difference of the average $PM_{2.5}$ concentration was about 5%. On the other hand, The TEOM sampler overestimated $PM_{2.5}$ mass concentration about 15% at low relative humidity (<80%).

• Korean Chemical Engineering Research
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• v.52 no.5
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• pp.688-693
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• 2014

For investigating NO reduction activity of an catalytic filter, the catalytic performance was measured under the presence of $SO_2$ and $H_2O$, respectively or simultaneously in the simulation gas composed of NO, $NH_3$, and air. The catalytic filter was prepared by coating $V_2O_5-WO_3/TiO_2$ catalyst on the pore surface of SiC filter element of which the superior performance for the particulate removal was well known. At the temperature below $260^{\circ}C$, the catalytic activities were enormously decreased under the presence of $SO_2$ and $H_2O$, respectively or simultaneously, compared with those under the cases of the absence of $SO_2$ and $H_2O$. However, the presence of $SO_2$ promoted the performance of the catalytic filter above $320^{\circ}C$ with showing the NO conversion better than 99.8% for the NO inlet concentration of 500 ppm and at the face velocity of 2 cm/s. In particular, the presence of water showed high NO conversion higher than 99% up to high temperature of $380^{\circ}C$. This effect of water was explained by the reason that it retarded the ammonia oxidation which is the main step into the formation of $N_2O$. The initial NO reduction activity of the catalytic filter maintained for the duration of 100 hours in the presence of $SO_2$ and $H_2O$. Therefore, it was concluded that the catalytic filter was promisingly useful for the industrial NOx reduction catalyst in order to treat the particulate and NO simultaneously.

• Progress in Superconductivity and Cryogenics
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• v.3 no.1
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• pp.64-68
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• 2001

An experimental study on the Joule-Thomson cryocooler with the mixed refrigerant (MR) is described in this paper, J-T refrigeration experiment was performed with a single stage regular air-conditioning compressor The mixed refrigerant in the experiment was composed of 75% mol fraction of $N_2$. 30% moi fraction of CH$_4$. 30% moi fraction of $C_2$H$_{6}$. 10% mot fraction of $C_3$H$_{8}$ and 15% mot fraction of iso-C$_4$H$_{10}$. Oil mist in the MR stream could be eliminated completely by the glass microfiber filter. Since a single stage compressor that had been designed thor R22 is not appropriate for high Pressure ratio of the mixed refrigerant especially during the transient period. two modifications were incorporated to regular J-T refrigeration cycle. First. a Portion of the MR was by-passed at the inlet of the heat exchanger and transferred directly to 7he suction of the compressor in the modified system. Second, a buffer volume was Prepared to change the mass flow rate of refrigerant. The pressure ratio in J-T expansion device was relieved at the beginning of the operation due to the by-Pass scheme. but it gradually decreased during the transient Process as some of the MR component condensed at low temperature. The buffer volume at the suction side was used to increase the MR gas density in the system after the transient cool-down period. Form the experiment with the modified system, the refrigerator could reach the lowest temperature of -152$^{\circ}C$ without cooling load. and about -15$0^{\circ}C$ with 5 W of cooling load . . . .

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.10
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• pp.871-876
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• 2016

Abnormal odor similar with burning smell often appears at the cockpit in the beginning of ultra-sonic aircraft without air filter due to the heating of production materials remained at the bleed air duct. Sources of the odor should be removed by burn-in test before test flight in order to prevent pilot confuses order with emergency such as fire of engine. However, the present method cannot prevent abnormal odor completely at the high altitude flight because maximum temperature of flight is higher than it of burn-in-test. This paper suggests burn-in test improved based on the analysis of thermal conditions of high altitude flight. It is verified that the existing burn-in test cannot cover thermal conditions of high altitude flight due to the discontinuous flow control, high change rate of temperature per unit time and difference between limit temperature of condenser and turbine. In order to overcome the limitations of current methods, the new burn-in test with continuous flow control are suggested. The continuous flow control are achieved by ram air inlet control. The effect of suggested method are verified by ground tests and flight tests. The results show the bleed air temperature can cover the temperature of high altitude flight and prevent abnormal odor at the flight test.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1368-1375
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• 2004

Measurements of OH chemiluminescence in an atmospheric pressure, laboratory-scale dump combustor at equivalence ratios ranging from 0.63 to 0.89 were reported. The signal from the first electronically excited state of OH to ground state was detected through a band-pass filter with an ICCD. The objectives of this study are two: One is to see the effects of equivalence ratio on global heat release rate and local Rayleigh index distribution. To get the local Rayleigh index distribution, the line-of-sight images were inverted by tomographic method, such as Abel do-convolution. Another aim is to investigate the validity of using OH chemiluminescence acquired with an ICCD as a qualitative measure of local heat release. For constant inlet velocity and temperature, the overall intensities of OH emission acquired at different equivalence ratio showed periodic and higher value at high equivalence ratio. OH intensity averaged over one period of pressure increased exponentially with equivalence ratio. Local Rayleigh index distribution clearly showed the region of amplifying or damping the combustion instability as equivalence ratio increased. It could provide an information/insights on active control such as secondary fuel injection. Finally, local heat release rate derived from reconstructed OH images were presented fur typical locations.