• Title/Summary/Keyword: Ambient Temperature

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A Study on Autoignition of Granulated Activated Carbon with Change of Ambient Temperature (주위온도 변화에 따른 입상활성탄의 자연발화에 관한 연구)

  • 목연수;최재욱
    • Journal of the Korean Society of Safety
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    • v.7 no.4
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    • pp.45-53
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    • 1992
  • Sponataneous ignition characteristics for granulated activated carbon were observed by performing experiments at constant ambient temperature and varying the ambient temperature sinusoidally. In case of varying the ambient temperature sinusoidally, the amplitudes of temperature were 5$^{\circ}C$, 1$0^{\circ}C$ and 15$^{\circ}C$ respectively, and the period in each amplitude was varied at an interval of 30minutes from zero to 3hours. As the results of experiments at a constant ambient temperature, the critical spontaneous ignition temperature of the sample decreased as the sample vessel size increased. Apparent activation energy of the sample calculated from the Frank-Kamenetskii's thermal Ignition theory was 38.82[kca1/mo1] In case of varying the ambient temperature sinusoidally, the critical spontaneous ignition tempera-ture was lower than that at the constant ambient temperature, and the minimum critical spontaneous ignition temperature decreased with the amplitude of heating sinusoidal curve. At the same amplitude, the critical spontaneous ignition temperature decreased until it reached the minimum point and then in-creased as the period increased.

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Characteristics of Impinging Diesel Spray on the Heated Flat Wall in High Temperature and High Pressure Environments (고온.고압 환경에서 가열평판에 충돌하는 디젤분무의 특성)

  • Im, Gyeong-Hun;Lee, Bong-Su;Kim, Jong-Hyeon;Gu, Ja-Ye
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.5
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    • pp.627-633
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    • 2001
  • Characteristics of a diesel spray impingement with the variation of ambient temperature, wall temperature and ambient pressure were investigated through shadowgraphy method by using high speed camera. The radial penetration of spray was increased with ambient temperature and wall temperature. It is resulted from the decrease of ambient gas density caused by the increase of temperature. The height of spray was also increased with ambient temperature and wall temperature, because the height of stagnate region is noticeably increased, although height of wall jet vortex is decreased. At the same ambient pressure, the area ratio of impinging spray of room temperature environment to high temperature environment was increased, as the temperature difference between room temperature and high temperature increases. And the increment of area ratio was higher at low ambient pressure than high ambient pressure.

Heat Production and Thermoregulatory Responses of Sheep Fed Different Roughage Proportion Diets and Intake Levels When Exposed to a High Ambient Temperature

  • Sudarman, A.;Ito, T.
    • Asian-Australasian Journal of Animal Sciences
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    • v.13 no.5
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    • pp.625-629
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    • 2000
  • Six yearling Suffolk ewes were used to study the effect of different roughage proportion diets (30%=LR, and 70%=HR) and intake levels (0.7 M and 1.3 M) on heat production and thermoregulatory responses in sheep exposed to different ambient temperatures (20 and $30^{\circ}C$). Sheep fed HR had higher heat production (HP) and time spent eating (TSE) and lower time spent standing (TSS) than those fed LR. But effect of roughage proportion on vaginal temperature (Tv) was obvious only at high intake and at $30^{\circ}C$. Sheep fed high intake had higher Tv, HP, TSS, and TSE than those fed low intake. Roughage proportion and intake level did not have an effect on respiration rate (RR), but ambient temperature did. Ambient temperature did not have an effect on HP, TSS and TSE. At $30^{\circ}C$ sheep had higher Tv and RR than those at $20^{\circ}C$. There were interactions between intake level and ambient temperature in TSS, between intake level and roughage proportion in TSE, and between roughage proportion and ambient temperature in HP. Results indicate that high roughage diet imposes a greater potential heat load on animals than low roughage diet when given at high ambient temperature, but not at low ambient temperature. And the effects is more pronounced at high intake.

The Characteristic Change of Pressure and Differential Transmitter due to a Rapid Change of Ambient Temperature (주위 온도의 급격한 변화에 따른 압력 및 차압 전송기의 특성 변화)

  • Chung, Jong-Tae;Ha, Young-Cheol;Lee, Cheol-Gu;Her, Jae-Young
    • 유체기계공업학회:학술대회논문집
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    • pp.321-326
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    • 2004
  • The pressure and differential pressure(DP) transmitters are used for gas flow rate calculation on the orifice gas metering system. On site, the pressure and DP transmitters are installed in a shelter to diminish the affects of environmental change such as an ambient temperature. But there has been an argument about the effectiveness of the shelter and this brought up the necessity to verify the affects of ambient temperature. These experiments were performed to verify the ambient temperature effects as observing the output of transmitters when the ambient temperature were changed from $-30^{\circ}C$ to $50^{\circ}C$. The results showed that the most of transmitters were operated in the spec range of performance criteria presented by manufacturer but the rapid change of ambient temperature could cause the larger measurement error for the DP transmitter of low span than others. Therefore the pressure and DP transmitters need to be operated and controlled within the proper range of ambient temperature.

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Performance Analysis of Hybrid Heat Pump System of the Air-to-Air/Air-to-Water with the Ambient Temperature (외기온 변화에 따른 공기-공기/공기-물 형태로 된 복합형 열펌프 시스템의 성능 특성 분석)

  • 송현갑
    • Journal of Biosystems Engineering
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    • v.25 no.4
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    • pp.273-278
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    • 2000
  • The hybrid heat pump system of the air to air and / or air to water was composed and its COP was analyzed with the ambient temperature on the opened and closed loop system respectively. The results be indicated by the equation(7) that the COP(Coefficient of Performance) of air-source(air to air and / or air-water) heat pump is effected with the ambient air temperature and AVACTHE.(Automatic Variable Area Capillary Type Heat Exchanger) 2. The COP of air-to-water heat pump without AVACTHE decreased in accordance with the ambient temperature decrease, however in case of the heat pump with AVACTHE the COP was maintained at 2.8∼3.0 level when the ambient temperature decrease from -$5^{\circ}C$ to $-11^{\circ}C$. 3. The COP of the air-to-water heat pump operated on the open loop was higher 40∼58% than that of the heat pump operated on the close loop. 4. The lower ambient temperature air effect on the COP of the air-to-air heat pump operated on the semi closed loop could be controlled using the AVACTHE, and at the high ambient air temperature the COP increased using the Bypass circuit.

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Effect of Ambient Air Temperature on the Pattern of Clothing Ventilation through Openings (환경 온도가 개구부를 통한 의복의 환기 양상에 미치는 영향)

  • 추미선
    • The Research Journal of the Costume Culture
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    • v.10 no.6
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    • pp.793-801
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    • 2002
  • The effects of ambient air temperature on the clothing ventilation were investigated numerically by a finite difference method. Numerical analysis using a 2-dimensional model comprising the air space between the skin and the clothing was conducted under the assumption that the clothing ventilation occurred only through the openings not through the fabric. The larger the temperature difference between the skin and the surroundings, the more apparent the thermal boundary layer As the ambient air temperature decreased, the air flow and the rate of the return of oxygen concentration to the atmosphere level in the clothing increased. Convection was dominant under low ambient air temperature, whereas conduction was dominant under high ambient air temperature. The ventilation rate was faster in the clothing microenvironment of the body part than that of the arm part.

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A Study on Autoignition of Fish Meal with Change of Ambient Temperature (주위온도 변화에 따른 어분의 자연발화에 관한연구)

  • 목연수;최재욱
    • Journal of the Korean Society of Safety
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    • v.7 no.1
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    • pp.47-56
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    • 1992
  • Spontaneous ignition charactenstics for fish meal were observed by performing experiments at constant ambient temperature and varying the ambient temperature sinusoidally. As the results of the experiments at a constant ambient temperature, the critical spontaneous ignition temperature of the sample for large, intermediate and small vessels was 170.5$^{\circ}C$, 177.5$^{\circ}C$ and 188.5$^{\circ}C$, respectively. The critical spontaneous ignition temperature decreased as the sample vessel size increased. Apparent activation energy of used fish meal calculated from the Frank-Kamenetskii's thermal ignition theory was 37.60Kcal/mol. In case of varying the ambient temperature sinusoidally, the amplitudes of temperature were 1$0^{\circ}C$, 2$0^{\circ}C$ and 3$0^{\circ}C$ respectively with the period in each amplitude 1hr, 2hrs and 3hrs. The results showed that the critical spontaneous ignition temperatures at the varied amplitudes of temperature were lower than that at the constant anbient temperature and increased as the amplitude increased. At the same amplitude, the critical spontaneous ignition temperature increased with the period.

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Thermoregulation on Menstrual Cycle -Effects of Ambient Temperatures- (생리주기에 따른 체온조절에 관한 연구 -환경온도의 영향을 중심으로-)

  • 황수경;최정화
    • Journal of the Korean Society of Clothing and Textiles
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    • v.25 no.2
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    • pp.339-349
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    • 2001
  • This study was investigated the effects of ambient temperatures and menstrual cycle on Resting Metabolic Rate(RMR), Rectal Temperature(Tre), Skin(forehead, chest, abdomen, forearm, hand, thigh, leg, foot) Temperatures, and subjective thermal sensations in 8 young Korean females(ages 22-25, voluntarily). The Tre and the Skin Temperatures were measured in once every five minute for one hour. RMR was measured three times at 30 minutes intervals by indirect calorimetry. All measurements were gathered during Luteal Phase(LP), Menstruation(M), and Follicular Phase(FP) at two levels of ambient temperatures; low(17~21$^{\circ}C$) and middle(21.1~$25^{\circ}C$). LP were the highest values during FP and M in RMR, Tre, forehead temperature, chest temperature and abdomen temperature, while the leg(leg and foot) and arm(forearm and hand) temperatures were higher during FP rather than during LP at each ambient temperature. The downward curve of Tre in the experiment was larger during FP than LP. The values in subjective thermal sensations were most comfortable during LP than M and FP at each ambient temperature. The LP-FP differences in core and mean skin temperatures, and resting metabolic rate, were more significant at middle ambient temperatures than at low ambient temperatures.

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Relative Anticipated Erythrocyte Sedimentation Rate of Cattle Blood, as Measured by 45 Degree-Angled Capillary Hematocrit Tube, for Ambient Temperature and PCV Value (소 혈액의 45도 경사 모세관에 의한 ESR측정에 있어서 환경온도 및 PCV에 상관하는 관계적 예기ESR치)

  • Lee, Bang-whan
    • Korean Journal of Veterinary Research
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    • v.27 no.2
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    • pp.339-345
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    • 1987
  • Each of twenty blood samples taken from apparently healthy Korean Cows was used to produce five different mixtures of autologous plasma and blood corpuscles such that their values of packed cell volume (PCV) lay between 10 to 50ml/l00ml. The measurements of erythrocyte sedimentation rate (ESR) using 45 degree-angled capillary hematocrit tube, 1.1-1.2mm bore, ($45^{\circ}-micro-ESR$) were practised for the blood of various levels of PCV under the ambient temperature of ${10^{\circ}C}$, ${20^{\circ}C}$ and ${30^{\circ}C}$. Correlation of ESR to ambient temperature showed linear regression each in five levels of PCV. ESR increased with ascending ambient temperature, and magnitude of the increase of ESR became greater as the level of PCV lowered. Correlation of ESR, of which values were transformed by the linear regression equation correlated to ambient temperature to PCV showed curvilinear regression each in three levels of ambient temperature, and ESR was increased with decreasing PCV. The data were statistically analysed and a list of relative anticipate $45^{\circ}-micro-ESR$ values for PCV and ambient temperature was presented.

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Numerical Study of Spray Characteristics of n-Heptane in Constant Volume Combustion Chamber under Diesel Engine Conditions (정적연소기를 이용한 디젤 엔진 조건에서 n-Heptane의 분무특성에 관한 수치해석 연구)

  • DAS, SHUBHRA KANTI;LIM, OCKTAECK
    • Transactions of the Korean hydrogen and new energy society
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    • v.27 no.6
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    • pp.727-736
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    • 2016
  • Numerical simulations of n-heptane spray characteristics in a constant volume combustion chamber under diesel engine like conditions with increasing ambient gas density ($14.8-142kg/m^3$) and ambient temperature (800-1000 K) respectively were performed to understand the non-vaporizing and vaporizing spray behavior. The effect of fuel temperature (ranging 273-313 K) on spray characteristics was also simulated. In this simulation, spray modeling was implemented into ANSYS FORTE where the initial spray conditions at the nozzle exit and droplet breakups were determined through nozzle flow model and Kelvin-Helmholtz/Rayleigh-Taylor (KH-RT) model. Simulation results were compared with experimentally obtained spray tip penetration result to examine the accuracy. In case of non-vaporizing condition, simulation results show that with an increment of the magnitude of ambient gas density and pressure, the vapor penetration length, liquid penetration length and droplet mass decreases. On the other hand vapor penetration, liquid penetration and droplet mass increases with the increase of ambient temperature at the vaporizing condition. In case of lower injection pressure, vapor tip penetration and droplet mass are increased with a reduction in fuel temperature under the low ambient temperature and pressure.