http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
콜로게이트 열교환기와 평판형 열교환기의 열전달특성에 관한 실험적 연구
박정훈(Jung-Hun Park),정용기(Yong-Ki Jeong),전층환(Chung-Hwan Jeon),장영준(Young-June Chang),임혁(Hyeok Lim) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
An experiment was performed to study heat transfer characteristics between corrugated heat exchanger<br/> and flat plate type one. While heat capacity(13.86kW) was provided constantly and the flow speed was<br/> varied from 2.8 to 17.9m/s, The temperature and the pressure drop were measured. Furthermore, Heat<br/> transfer coefficient, Colburn factor and Nusselt number were calculated using them. With increase of<br/> the flow speed for both exchangers, the coefficient and the pressure drop increased, but Colburn factor<br/> decreased. The coefficient, pressure drop and Colburn factor of the corrugated type were all higher than<br/> those of the flat one, which is due to the flow interruption with recirculation and reattachment of the<br/> corrugated type. The empirical correlations of Nusselt number were suggested for the tested two heat<br/> exchangers.
희박 예혼합 모형 가스터빈 연소기의 화염구조와 배기특성에 관한 실험적 연구
문건필(Gun Feel Moon),이종호(Jong Ho Lee),전층환(Chung Hwan Jeon),장영준(Young June Chang) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
The objective of this study is a qualitative comparison between line-integrated OH chemiluminescence<br/> (OH*) image and its Abel inversion image at different phase of the oscillating pressure field.<br/> PIV(Particle Image Velocimetry) measurements were conducted under non-reacting conditions to see<br/> the global flow structure. Also NOx emission was measured to investigate the effect of fuel-air<br/> premixing on combustion instability and emission characteristics. Experiments were carried out in an<br/> atmospheric pressure, laboratory-scale dump combustor operating on natural gas. Combustion instabilities<br/> in present study exhibited a longitudinal mode with a dominant frequency of ~341.8 Hz, which<br/> corresponded to a quarter wave mode of combustor. Heat release and pressure waves were in-phase<br/> when instability occurred.<br/> Results gave an insight about the location where the strong coherence of pressure and heat release<br/> existed. Also an additional information on active control to suppress the combustion instabilities was<br/> obtained. For lean premixed combustion, strong correlation between OH* and NOx emissions was<br/> expected largely due to the exponential dependence of thermal NOx mechanism on flame temperature.
메탄 공기 층류 부분 예혼합화염에서 예혼합 정도에 따른 화염구조와 질소산화물의 배출에 미치는 영향에 관한 연구
오정석(Jeong Seog Oh),정용기(Yong Ki Jeong),전층환(Chung Hwan Jeon),장영준(Young June Chang) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
It is shown that the effect of variable parameters on flame structures and NOx emissions in the laminar<br/> partially premixed methane-air flames with a co-axial Bunsen burner. Objectives of this paper is to<br/> understand the effects of flow variables on NOx emissions and the flame structure with OH<br/> chemiluminescence, including reconstructed image by abel inversion processing at each conditions. A fuel<br/> flowrate of 200 [cc/min] was fixed and the amount of air was varied from 400 to 1200 [cc/min]. The<br/> experimental variables were equivalence ratio( ), fuel split percentage( ) and inner tube recess(x/D). Flow<br/> conditions were ranged from 1.36~4.76(equivalence ratio), 50~100(fuel split percentage) and 0~20(inner<br/> tube recess). NOx analyzer and ICCD camera with a OH filter were used as a main experimental<br/> apparatus. In addition, Abel inversion, which is a kind of tomography and valuable to estimate a<br/> two-dimensional structure of co-axial flames from cubical information, was employed for combustion<br/> diagnostics. Results from this study indicate that the main effects depend on equivalence ratio and next<br/> sigma, x/D for NOx production and OH formation. Throughout Abel inversion, we could affirm the<br/> maximum position and the tendency of OH radical intensity by variants at five axial heights above the<br/> burner exit.