• Journal of the Korean Wood Science and Technology
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• 제33권4호통권132호
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• pp.38-44
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• 2005

본 연구는 Monoammonium phosphate, Sodium borate 및 Zinc borate를 이용하여 난연성 수용액을 배합하고, 이를 이용하여 난연처리한 목재의 연소특성을 검토하기 위하여 수행하였다. 난연처리한 목재의 연소특성은 열분석(TGA, 연소열)과 난연시험(LOI, 화염전파)을 이용하여 수행하였다. 열분석과 난연시험의 결과는 다음과 같다. 1) F4로 처리한 시료가 거의 모든 연소 특성에 있어 우수한 난연효과를 나타내었다. 2) TGA curve로부터, 모든 시료는 열분해와 산화과정을 가짐을 알 수 있었다. 3) 연질목재에 대한 난연효과가 경질 목재보다 효과적이며, 난연제의 함량이 증가함에 따라 연소열은 감소하였다. 4) 난연처리된 목재의 LOI값은 24~30으로 거의 비슷하였으나 이들 값들은 비처리된 목재시료의 LOI값보다 높게 나타났다. 5) Monoammoum phosphate, Sodium borate, Zinc borate, Sodium hydroxide에 의해 배합된 수용성 난연제의 pH는 약 8.4로 옅은 암모니아 냄새가 났다.

• 동력기계공학회지
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• 제22권1호
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• pp.48-55
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• 2018

It has recently been reported that methanol fuel has been used in the product carrier with established duel fuel engine, which has been greatly reducing emissions of $CO_2$, NOx and SOx from the engine. However, to use methanol alone as fuel oil in a general diesel engine, design modification of cylinder head is needed because the ignition aid device or the duel fuel injection system is needed. On the other hand, only if the mixer is installed on the fuel oil supply line, diesel oil - methanol blending oil can be used as fuel oil for the diesel engine, but there is a problem of the phase separation when two fuels are mixed. In this study, diesel oil and methanol were blended compulsorily in preventing the phase separation with installing agitators and a fuel oil boost pump on fuel line of a test engine. Also, cylinder pressure and fuel consumption quantity were measured according to engine load and methanol blending ratio, and indicated mean effective pressure, heat release rate and combustion temperature obtained from the single zone combustion model were analyzed to investigate the effects of latent heat of vaporization of methanol on combustion stability and characteristics. As a result, the combustion stability and characteristics of 10% methanol blending oil are closest to the those of diesel oil, and it could be used as fuel oil in existing diesel engines without deterioration of engine performance and combustion characteristics.

• 한국연소학회지
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• 제12권2호
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• pp.34-41
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• 2007

The dynamic behaviors of counterflow non-premixed flame have been investigated experimentally to study effects of heat losses and Lewis number on edge flame oscillation, which result from the advancing and retreating edge flame motion of outer flame edge at low strain rate flame. For low strain rate flame, lateral conduction heat loss in addition to radiation heat loss could be more remarkable than the others. Oscillatory instabilities appear at fuel Lewis number greater than unity. But excessive lateral conduction heat loss causes edge flame instability even at fuel Lewis number less than unity. The excessive heat loss caused by the smaller burner diameter in which the flame length is an indicator of lateral conduction heat loss extends the region of flame oscillation and accelerates oscillatory instability in comparison to the previous study with the burner diameter of 26mm. Extinction behaviors quite different from the previous study are also addressed.

• 한국연소학회지
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• 제18권2호
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• pp.23-31
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• 2013

Compact steam boiler is a useful heat exchanger in a space-intensive system. There are some constraints in terms of sizing and designing the space confined in the system which is usually used in vessels. In this study, design considerations for heavy duty heat exchangers of compact steam boilers are presented and evaluated. Especially, evaporator tubes of marine boiler which are exposed to a high temperature environment are considered. Also, extended surface designs with a high temperature are examined. In order to determine the criteria with considerations of both heat transfer rate and pressure drop in the heat exchanger, they are evaluated with major variables, such as the tube diameter, the number of tubes, and the tube length. Finally, the design parameters are estimated as the bare tubes are installed instead of the finned tubes.

• 한국화재소방학회논문지
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• 제18권2호
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• pp.67-72
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• 2004

본 연구는 작업장의 건축물이나 구조물의 구성요소로 사용되어지는 섬유강화플라스틱의 연소특성을 평가하였다. 섬유강화플라스틱의 연소특성은 ISO 5660에 따라 콘칼로리미터를 사용하여 수행하였다. 섬유 강화플라스틱의 착화시간과 열방출율은 복사열과 난연제의 함량에 따라 달랐다. 섬유강화플라스틱의 열방출율은 복사열의 증가에 따라 증가하였다. 섬유강화플라스틱의 착화시간과 최대 열방출율을 이용하여 플래쉬오버(Flashover)의 가능성을 Petrella가 제시한 분류방법에 따라 검토하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제28권2호
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• pp.163-184
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• 2004

Vortex flow fundamentals have been investigating for about hundred years and many distinguished features had been discovered and comprehensively studied over that time. Due to unique hydrodynamic features vortex flows are now widely used in many industrial applications, including energy and power systems. combustion chambers. fuel sprayers. heat exchangers. clean-up systems. drying chambers. Up to recently aerospace engineers employed vortex flow only in combustion systems to stabilize a flame zone or in advanced heat exchangers to enhance heat transfer processes. This paper provides an overview of some recently developed aerothermal vortex technologies applied to aerospace engineering.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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• pp.207-214
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• 2004

Extra heavy vacuum residue oil has advantage as the fuel of a power plant in reducing the cost of power generation. Numerical study is conducted by the KIVA code to understand combustion, heat transfer and flow field characteristics in the test reactor. The combustion model of pulverized coal particles is adopted as the combustion process of extra heavy oil is similar to that of coal. As an initial phase of investigation parametric study is performed with respect to SMD and spray angle of injected spray droplets.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제20회 춘계학술대회 논문집
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• pp.240-243
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• 2003

Combustion instability phenomena have been observed in various different combustion systems. For each specific combustion system, pressure fluctuations measured during high frequency combustion instability presented many different characteristics. High frequency instability occurring in a lean premixed gas turbine combustor mar be dominantly affected by a nonlinear relation between pressure oscillations and heat release rate fluctuations, and gas dynamics plays a crucial role in determining an amplitude of a limit cycle for a liquid rocket thrust chamber. Combustion instability phenomena manifest their inherent nonlinear characteristics. One is a limit cycle and the other bifurcation described by nonlinear time series analysis.

• 대한기계학회논문집B
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• 제22권8호
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• pp.1183-1194
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• 1998

This paper describes a theoretical model developed for analyzing the heat transfer of automotive cooling systems. From the model, heat transfer rate of automotive cooling systems can be predicted, providing useful information at the early stages of the design and development. The aim of the study is to develop a simulation program for automotive cooling system analysis and a performance analysis program for analyzing heat exchanger. Heat release rate from combustion gas to coolant through cylinder wall in engine cylinder was analyzed by using a two zone combustion model. This paper studied how cooling condition would affect engine heat release rate and measured temperature distribution of coolant in water jacket.

• 대한기계학회논문집B
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• 제21권11호
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• pp.1466-1474
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• 1997

In order to design and develop a spark ignition engine, many studies must be preceded about the characteristics of thermal flow. For measurement of transient wall temperature thin film thermocouples of Bendersky type were manufactured and these probes were fixed into the wall of combustion chamber. Surface wall temperatures were measured in experiments of various engine speeds. Transient heat fluxes were calculated from the wall temperature measurements. Pressure was measured from combustion chamber using pressure transducer and gas temperatures were calculated using the state equation of ideal gas. And instantaneous heat transfer coefficients were obtained. It will be the basic data for the formulae of instantaneous heat transfer coefficients.