http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
완전혼합영역을 갖는 성층축열조의 충전과정에 대한 이론적인 해석
유호선,박이동,Yoo, H.,Pak, E.T. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.2
A theoretical one-dimensional model for the charging process in stratified thermal storage tanks is established presuming that the fluid ensuing from the tank inlet creates a perfectly mixed, layer above the thermocline. Both the generic and asymptotic closed-form solutions are obtained via the Laplace transformation. The asymptotic solution describes the nature of the charging pertaining to the case of no thermal diffusion, whereas the generic solution is of practical importance to understand the role of operating parameters on the stratification. The present model is validated through comparison with available experimental data, where they agree well with each other within a reasonable limit. An interpretation of the exact solution entails two important features associated with the charging process. The first is that an in-crease in the mixing depth $h_m$ causes a relatively slow temperature rise in the perfectly mixed region, but on the other hand it results in a faster decay of the overall temperature gradient across the thermocline. Next is the predominance of the mixing depth in the presence of the prefectly mixed region. In such a case the effect of the Peclet number is marginal and there-fore the thermal characteristics are solely dependent on the mixing depth paticularly for large $h_m$. The Peclet number affects significantly only for the case without mixing. Variation of the storage efficiency in response to the change in the mass flow rate agrees favorably with the published experimental results, which confirms the utility of the present study.
유호선,박이동,Yoo, H.,Pak, E.-T. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.1
In order to establish a theoretical basis for the analyses of transient behaviors in stratified thermal storage tanks, analytical approaches to an improved one-dimensional model are made. In the present model the storage tank is treated as a finite region with an adiabatic tank exit, whereas it has been considered as a simple semi-infinite region previously. Application of the Laplace transformation and the Inversion theorem to the governing equations makes it possible to obtain an exact infinite-series solution, which is convergent only at sufficiently large time. Accordingly a complementary solution which is available for short times, i.e., the time range of this study is sought by an approximate method. The approximate solution which is rigorously validated through the examination of neglected terms in the solution procedure agrees quite well with the exact one. Moreover, it is simpler to use and more convenient to interpret the physical meaning of the solution. Comparison of the present solution with the previous ones shows relatively large difference near the tank bottom, which results from the more realistic boundary condition adopted in the present model. Some representative results by the approximate solution including effects of the Peclet number on temperature distrbutions are illustrated to show the utility of this study. In consequence, it is expected that the present results based on the improved model replace the foregoing ones as a new theoretical reference for studies of thermal stratification fields.
유호선,김영인,Yoo, H.S.,Kim, Y.I. 대한설비공학회 1989 설비공학 논문집 Vol.1 No.1
This paper presents an analysis to predict thermal behaviors of water in ice storage tank during the coldness release process. To deal with complicated transient phenomena due to ice-water phase change and the density inversion, a theoretical model which consists of initial perfectly mixed, stratified and thermal diffusion state was introduced and a criterion on the growth of thermal boundary layer was developed. The analysis includes considerations on the type of ice-making heat exchanger, refrigerator on/off and tank arrangement. Also, discussions on the various parameters and operating conditions which have influence on the performance of the system were made. Finally, simulated results were shown, which agreed with experiments in trends reasonably.
[가솔린엔진부문] 상용기관 연소실 형상을 갖는 정적 연소기에서의 플라즈마 제트 점화에 의한 연소특성
류현욱(H.W.Ryu),박정서(J.S.Park),유호선(H.S.Yoo),김문헌(M.H.Kim) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1999 No.11_1
In this paper. combustion characteristics ignited by single-hole and multi-hole plasm jet igniter and conventional spark plug have been studied by means of schlieren photography and pressure measuring in the Pent-roof type and the Toroidal bowl type constant volume vessel which is typical 4-valve 51 engine combustion chamber. It is represented that combustion characteristics ignited by conventional spark plug ignition are hardly influenced by configurations of combustion chamber. In contrast. in case of plasma jet ignition, combustion duration and combustion enhancement rates are effected than spark plug ignition. Consequently. it is important to avoid plasma jet impingement against combustion chamber wall. and to let flame front move toward wide place in the combustion chamber at early stage of combustion
정재동,정인성,유호선,이준식,Chung, J.D.,Jung, I.S.,Yoo, H.,Lee, J.S. 대한설비공학회 1997 설비공학 논문집 Vol.9 No.3
This paper presents a theoretical model for predicting transient behaviors during storage process of the cool storage system using the R141b clathrate. Introduction of the lumped capacitance method along with a brine reservoir having large thermal capacity yields a set of simplified energy equations. Based on the Arrhenius equation and the known experimental findings, the formation rate of clathrate for which the degree of subcooling is properly accounted is newly developed. An effective nondimensionalization of the model equations facilitates the closure of modeling as well as parametric study. Calculated results for a specific case not only simulate a typical pattern of temperautre variation in the tank successfully, but also agree reasonably well with available data. The effect of each characteristic parameter on the system performance is also investigated. It is revealed that the dominant among relevant parameters are the activation energy of reaction, the degree of subcoling and the initial mass fraction of refrigerant. Finally, the uncertainty associated with modeling of the shaft work variation appears to need further studies.
재생기 및 냉각기가 VM열펌프의 냉방성능에 미치는 영향
이건태,강병하,유호선,이재헌,Lee, G.T.,Kang, B.H.,Yoo, H.,Lee, J.H. 대한설비공학회 1997 설비공학 논문집 Vol.9 No.3
An experimental study has been carried out to investigate the effects of the combination of the different wire mesh number in a regenerator and the tube number in a cooler on the cooling performance of a Vuilleumier cycle heat pump. Effects of operating conditions, such as charging pressure, operating speed, and heat input, on the cooling performance are also studied. The experimental results obtained indicate that the cooling performance could be improved with the proper combination of different wire meshes in a regenerator. More tubes in a cooler are desirable for better cooling performance. It is also found that the cooling capacity is enhanced, whereas COP is reduced with an increase in the heater tube temperature and the revolution speed. Both the cooling capacity and COP are incereased with a higher charging pressure.
정병용(B.Y. Jeong),이재헌(J.H. Lee),여영구(Y.K. Yeo),문승재(S.J. Moon),유호선(H.S. Yoo) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
The booster fans for the flue gas desulfurization(FGD) plant of heavy oil fired 200㎿ power plant transport the flue gas from the boiler to the FGD Plant. The fan is exposed to the gases contained sulphur dioxide and nitrous oxides together with moisture, soot particles and small amounts of ash. Blades need rotary motion and adequate corrosion-erosion resistance at the same time. A solution to the both of them, they has been used Metcoloy®2 as protective coating but it is failed. In this study, investigated the coating failure of the blades of booster fans. Bond strength tests and practical field experiences have demonstrated that High Velocity Oxy-fuel(HVOF) coating method with Diamalloy 3004, as and alternative to Metcoloy®2