• 한국자동차공학회논문집
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• 제3권5호
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• pp.56-63
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• 1995

In this paper, the fuel atomization effect of a spark-ignition engine on the lean burn characteristics is studied. The fuel atomization is enhanced by heating the inside of the intake manifold with electric heater. Several operating parameters including cyclic variation are expressed against the air-fuel ratio from the experimental results. The fuel atomization gives much influence on the combustion stability. As the intake manifold is heated, the combustion duration decreased and the value of COV in the lean region as well as in the theoretical equivalence ratio became smaller than of not-heated.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제26회 춘계학술대회논문집
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• pp.321-326
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• 2006

초음속 유도무기에 사용되고 있는 공기흡입 추진기관의 지상 연소시험에서 요구되는 700K-6바의 공기를 공급하기 위한 Vitiated형 공기 가열기에 대한 개념설계를 수행하였다. 본 가열기는 여분의 기체 산소와 공기를 혼합하는 예혼합기, 예혼합 기체와 연료를 혼합시키는 혼합기, 점화기를 포함하는 연소실과 수축팽창 노즐, 그리고 디퓨저로 구성하였다. 가열기에 사용된 연료는 천연가스이며, 유동해석을 통해 가열기의 각 구성요소의 성능을 파악하였으며, 점화 후 화염유지가 이루지는 것을 해석적으로 확인하였다.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.27-36
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• 2020

Natural convection and thermal stratification phenomena are found in large water pools that are being used as heat sinks for decay heat removal from the reactor core using passive heat removal systems. In this study, the two-phase (water and air) natural convection and thermal stratification phenomena with conjugate heat transfer in the rectangular enclosure were investigated numerically using ANSYS Fluent 17.2 code. The transient numerical simulations of these phenomena in the full-scale computational domain of the experimental facility were performed. Generation of water vapour bubbles around the heater rod and evaporation phenomena were included in this numerical investigation. The results of numerical simulations are in good agreement with experimental measurements. This shows that the natural convection is formed in region above the heater rod and the water is thermally stratified in the region below the heater rod. The heat from higher region and from the heater rod is transferred to the lower region via conduction. The thermal stratification disappears and the water becomes well mixed, only after the water temperature reaches the saturation temperature and boiling starts. The developed modelling approach and obtained results provide guidelines for numerical investigations of thermal-hydraulic processes in the water pools for passive residual heat removal systems or spent nuclear fuel pools considering the concreate walls of the pool and main room above the pool.

• Journal of Advanced Marine Engineering and Technology
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• 제24권5호
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• pp.16-24
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• 2000

In this study, using frying oil, performance of engine and emission concentration were compared with the case of using diesel oil. And results are as follows. 1. Engine torque and brake horse power indicate nearly same value as the case of using diesel fuel. 2. Temperature of exhaust gas was increased with as high engine speed and load. 3. To reduce concentration of hydrocarbon, it is effective to operate using used frying oil in low engine speed and load, and adding LPG in high engine speed and load. 4. Concerning with concentration of carbon mono oxide and smoke emission, it was assured, that as engine load increased, lower concentration emitted in case of utilizing mixed fuel than that of utilizing pure diesel fuel.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.III
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• pp.639-646
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• 2000

Hot air heater with light oil combustion is the most common heater for greenhouse heating in the winter season in Korea. However, since the heat efficiency of the heater is about 80%, considerable unused heat in the form of exhaust gas heat discharges to atmosphere. In order to capture this exhaust gas heat a heat recovery system for plant bed heating in the greenhouse was built and tested in the hot air heating system of greenhouse. The system consists of a heat exchanger made of copper pipes, ${\phi}\;12.7{\times}0.7t$ located inside the rectangular column of $330{\times}330{\times}900mm$, a water circulation pump, circulation plastic pipe and a water tame The total heat exchanger area is $1.5m^2$, calculated considering the heat exchange amount between flue gas and water circulated in the copper pipes. The system was attached to the exhaust gas path. The heat recovery system was designed as to even recapture the latent heat of flue gas when exposing to low temperature water in the heat exchanger. According to performance test it can recover 45,200 to 51,000kJ/hr depending on the water circulation rates of 330 to $690{\ell}$/hr from the waste heat discharged. The exhaust gas temperature left from the heat exchanger dropped to $100^{circ}C$ from $270^{circ}C$ by the heat exchange between the water and the flue gas, while water gained the difference and temperature increased to $38^{circ}C$ from $21^{circ}C$ at the water flow rate of $690{\ell}$/hr. And, the condensed water amount varies from 16 to $43m{\ell}$ at the same water circulation rates. This condensing heat recovery system can reduce boiler fuel consumption amount in a day by 34% according to the feasibility study of the actual mimitomato greenhouse. No combustion load was observed in the hot air heater.

• 한국유체기계학회 논문집
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• 제12권5호
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• pp.7-12
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• 2009

A nuclear fuel test loop(after below, FTL) is installed in the IRI of an irradiation hole in HANARO for testing the neutron irradiation characteristics and thermo hydraulic characteristics of a fuel loaded in a light water power reactor or a heavy water power reactor. There is an in-pile section(IPS) and an out-pile section(OPS) in this test loop. When HANARO is operated normally, the fuel loaded into the IPS has a nuclear reaction heat generated by a neutron irradiation. To remove the generated heat and to maintain the operation conditions of the test fuel, a main cooling water system(MCWS) is installed in the OPS of the FTL. The MCWS is composed of a main cooler, a pressurizer, two circulation pumps, a main heater, an interconnection pipe line and instruments. The interconnection pipeline is a closed loop which is connected to an inlet and an outlet of the IPS respectively. The MCWS is under a cold function test during a start-up period. This paper describes the system flow network analysis results of the flow control of a main cooling water system in the HANARO fuel test loop. It was confirmed through the results that the flow was met the system design requirements.

• 한국수소및신에너지학회논문집
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• 제32권5호
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• pp.324-330
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• 2021

In recent years, polymer electrolyte membrane fuel cell (PEMFC) based cogeneration system has received more and more attention from energy researchers because beside electricity, the system also meets the residential thermal demand. However, the low-quality heat exited from PEMFC should be increased temperature before direct use or storage. This study proposes a method to utilize the heat exhausted from a 10 kW PEMFC by coupling a heat pump. Two different configuration using heat pump and a reference layout with heater are analyzed in term of thermal and total efficiency. The system coefficient of performance (COP) increases from 0.87 in layout with heaters to 1.26 and 1.29 in configuration with heat pump and cascade heat pump, respectively. Lastly, based on system performance result, another study in economics point of view is proposed.

• 대한기계학회논문집
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• 제19권1호
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• pp.277-283
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• 1995

For the development of low NO$_{x}$ gas burners aimed for absorption chiller/heater unit, three proto type burners of different capacity (265000, 498000, and 664000 kcal/h) have been manufactured through a combustion method of step-by-step air injection. In order to characterize the overall features of the flame and the properties of the emission gas, the temperature of the flame and the concentration of NO$_{x}$ and CO were determined. The main factors in the design of burners (the area of primary air injection, the diameter of secondary air injection hole, fuel nozzle diameter) were observed to increase linearly with the scale-up of burner capacity. The flame temperature profiles of the burners were observed to be almost similar, irrespective of their capacity. However, as their capacity increased, the flame temperature slightly increased and the hot region of the flames moved to ward the flame tip along with the expansion to the direction of radius. From the proto type units, the amount of their NO$_{x}$ emission was determined to be around 25 - 30 vppm(3% )$_{2}$) and the CO emission was less than 19 vppm (3% $O_{2}$).TEX>).

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.349-352
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• 2010

본 연구는 스크램젯의 연소특성 연구 및 스크램젯 엔진의 지상연소시험의 필수 장비인 공기가열기의 개념 연구에 대한 것이다. 공기가열기는 스크램젯의 흡입구나 연소실로 고온의 공기를 공급하기 위한 다양한 방법 중 하나이며, 고온의 연소가스와 실제 공기에 보다 유사한 혼합기체(혼합공기)를 얻을 수 있는 연료를 사용하여야 한다. 본 연구에서는 이러한 형식을 갖는 외국의 공기가열기를 조사하고, 스크램젯 비행체를 개발하기 위한, 액화천연가스(CH4)와 수소를 연료로 사용하는 공기가열기의 인젝터를 개념 설계하였다.

• 한국산학기술학회논문지
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• 제16권11호
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• pp.7250-7255
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• 2015

본 논문은 전기자동차의 주행 거리 향상을 위한 전기자동차용 연소식 공기 히터를 개발하기 위하여 기존 디젤 연소식 공기 히터의 난방성능에 대한 실험 및 분석을 실시하였다. 본 연구에서 사용된 연소식 공기 히터의 성능 분석을 위하여, 히터의 열용량 계산과 실차 실험을 통한 온도 변화를 고찰하였다. 승차공간으로 공급되는 난방 공기의 온도는 $101.3^{\circ}C$이며 연소식 공기 히터 내부 히트싱크의 표면 온도 편차는 위치에 따라 67.8% 차이를 나타내었고 공기 히터의 난방 열량은 2.0 kW로 산출되었다. 또한 연소식 공기 히터의 실차적용 실험에서 차량 승차공간의 내부 온도는 지속적으로 상승하였고 1800초 후 승차공간의 상부 공기 온도는 $42.5^{\circ}C$이고, 하부 공기 온도는 $25.3^{\circ}C$로 나타났으며 디젤 연소식 공기 히터의 난방 효율은 평균 63.7%로 산출되었다.