• 한국초전도ㆍ저온공학회논문지
• /
• 제14권4호
• /
• pp.50-53
• /
• 2012

This paper describes experimental study on GM-type pulse tube refrigerator (PTR). In a PTR, the pulse tube is only filled with working gas and there exists secondary flow due to a large temperature difference between cold-end and warm-end. The stability of secondary flow is affected by orientation of cold-head and thus, the cooling performance is deteriorated by gas mixing due to secondary flow. In this study, a single stage GM-type pulse tube refrigerator is fabricated and tested. The cooing performance of the fabricated PTR is measured as varying cold-head orientation angle and the results are used as reference data. Then, we divided interior space of pulse tube into three segments, and fixed the various size of screen mesh at interface of each segment to suppress the performance degradation due to secondary flow. For various configuration of pulse tube, no-load test and heat load test are carried out with the fixed experimental condition of charging pressure, operating frequency and orifice valve turns. From experimental results, the fine screen mesh shows the effective suppression of performance degradation for the large orientation angle, but the use of screen mesh cause the loss of cooling capacity rather than the case of no insertion into pulse tube. It should be compromised whether the use of screen mesh in consideration of the installation limitation of a GM-type pulse tube refrigerator.

• 한국산학기술학회논문지
• /
• 제15권2호
• /
• pp.653-659
• /
• 2014

자동차용 LPI 연료필터 하우징의 냉간단조 공정에 대한 성형해석을 수행하였다. 변형과 하중의 분배를 고려하여 금형과 시제품을 제작하였다. 또한 기존 모델과 신규 모델의 유동 특성을 분석하기 위하여, 유동해석을 수행하였다. 유동해석 결과, 두 모델은 동등한 압력강하량을 나타내었다. 기존 제품 대비, 상부 하우징은 16 g, 하부 하우징은 30.5 g이 감소하여, 총 46.5 g의 중량이 감소하였다. 안정성을 검증하기 위해서 기밀시험 및 내압시험을 수행하였으며, 시험 기준을 만족하였다.

• 한국초전도ㆍ저온공학회논문지
• /
• 제14권3호
• /
• pp.48-52
• /
• 2012

This paper describes experimental study on the orientation dependence of GM-type pulse tube refrigerator with helium and neon as working gas. A pulse tube refrigerator generates refrigeration work with gas expansion by gas displacer in the pulse tube. The pulse tube is only filled with working gas and there exists secondary flow due to large temperature difference between cold-end and warm-end. The stability of secondary flow is affected by orientation of cold-head and thus cooling performance is deteriorated by gas mixing due to secondary flow. In this study, a single stage GM-type pulse tube with orifice valve as a phase control device is fabricated and tested. The fabricated pulse tube refrigerator is tested with two different working gases of helium and neon. First, optimal valve opening and operating frequency are determined with experimental results of no-load test. And then, the variation of no-load temperature as orientation angle of cold-head is measured for two different working gases. Effect of orientation dependence of cold-head as working gas is discussed with experimental results.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2009년도 제33회 추계학술대회논문집
• /
• pp.119-122
• /
• 2009

본 연구는 친환경 추진제인 과산화수소($H_2O_2$)와 케로신을 추진제로 하는 액체 로켓 엔진에서의 막냉 각 장치 개발을 목적으로 이를 위하여 막냉각링을 설계/제작하고, 수류 시험을 통해 분무 특성과 공급 유량을 확인하였다. 또한 설계/제작된 막냉각링의 성능 예측을 위하여 열해석을 수행하였다. 수류 실험 결과 설계 유량(42.25g/s)이 공급됨을 확인하였고, 상대적으로 유속이 빠르고 홀 개수가 많은 막냉각링이 더 좋은 분무패턴을 보임을 확인하였다. 또한 열해석 결과 설계된 막냉각링이 충분한 냉각 성능을 가짐을 확인하였다.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2007년도 제34회 KOSCO SYMPOSIUM 논문집
• /
• pp.168-175
• /
• 2007

Ash melting chamber is one of the key facility of the pyrolysis-melting incineration system, and it should be designed and operated very carefully for avoiding solidification of slag. In this study, an example of numerical and experimental scale-up process of the melting chamber, in which high speed air is injected to the molten slag and generates bubbles, which enhances agitation of the slag and char combustion, is presented. Cold flow test, combustion and melting test in a lab-scale (30 kg/hr) chamber and a pilot scale (200 kg/hr) chamber. Minimum energy for maintaining molten slag is derived, and it was found that the molten slag can be maintained efficiently by concentrating heat into the bubbling slag.

• 소성∙가공
• /
• 제7권6호
• /
• pp.530-538
• /
• 1998

Elimination of the heat treatment process is very important in automation of metal forming since controlling heat treatment by computer has many difficulties and it has bottle neck problem. non-heat-treated steels materials which are not in need of heat treatment have been developed for cold forging. However to apply non-heat-treated steel to structural parts. it is necessary to prove reliability of mechanical properties. In order to define the reliability of mechanical properties we have investigated microstructure, hardness, the tensile strength compressive strength and tensile fatigue strength for both steels. Considering the results of high cycle fatigue test for both specimen the characteristics of non-heat-treated steel are decided on the yield strength, It has same tendency for heat-treated steel. Therefore non-heat-treated steel which has the appropriate yield strength may be applied in cold forging.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
• /
• pp.632-636
• /
• 2017

본 연구에서는 극초음속 추진기관을 위한 고공 환경 모사 시험 장치를 설계하였다. 설계된 사항을 기반으로 시험설비를 구축하였고, 상온 시험을 이용한 실험을 진행하였다. 상온 시험은 시험 모델의 유/무에 따라서 수행하였고, 본 연구에서 설계된 설비는 시험 모델의 유/무에 따라서 압력의 큰 변화가 없이 동일한 구현 조건을 모사하는 것을 확인할 수 있었다. 향후 시험 모델에 따른 변수 실험에 일부 적용될 데이터베이스를 확보하였다.

• 한국추진공학회지
• /
• 제17권2호
• /
• pp.46-56
• /
• 2013

고온 공기 공급시스템이 있는 시험장치는 분출냉각 소재를 개발하고 이를 실험적으로 평가하는데 필요한 장치이다. 본 연구에서 아크-플라즈마 발생기, 찬 공기가 공급되는 Plenum 챔버, 시험부로 구성된 시험장치를 설계하였으며, 내부 유동해석을 수행하였다. CFD 결과로부터 설계된 Plenum 챔버가 열적으로 안전하고 챔버 내부에서 초고온의 공기와 찬 공기가 잘 혼합되고 있음을 확인할 수 있었다. 또한, 시험부로 균질한 유동을 공급할 수 있는 구조로 시험장치가 설계되었음을 검증하였다.

• 한국분무공학회지
• /
• 제26권1호
• /
• pp.9-17
• /
• 2021

Six shear coaxial injectors with different recess length and taper angle were manufactured. Cold-flow tests on the injectors were performed at room temperature and pressure using water and air as simulants. By changing the water mass flow rate and air mass flow rate, spray images were taken under single-injection and bi-injection. Breakup length and spray angle were analyzed from instantaneous and averaged spray images using image processing techniques. For all the injectors, the breakup length generally decreased as the momentum flux ratio increased at the same gas mass flow rate. The injectors with 7.5° taper angle usually had the longest breakup length and the smallest spray angle. When the taper angle was 15° or more, it hardly affected breakup length and spray angle. The recess length did not influence breakup length but its effect on spray angle depended on the taper angle.

• 한국주거학회논문집
• /
• 제19권1호
• /
• pp.79-88
• /
• 2008

Hot water is used by having a wash, dishes, taking tub and drinking water in residential buildings, and the use objective is to raise comfort of human body sense, washing and sterilization effect and so on. Cold & hot water supply system is understanded simpler than HVAC systems relatively, so it is true that pace of performance improvement is slower than other systems for plan and technical development. In this study, the performance evaluations are conducted under the condition of composition ratio by 1:1 for cold & hot water supply manifold system using functionally complex valves such as constant flow regulating valve and 3-way mixing valve in the area of $105.6m^2$ apartment which consist of the largest part of the whole apartment. Also, flow rate related to simultaneous use of faucets and change of hot water temperature are compared with the existing method.