휜-관 열교환기의 착상 성능 최적화

양동근,이관수,Yang Dong-Keun,Lee Kwan-Soo 대한설비공학회 2005 설비공학 논문집 Vol.17 No.11

The optimization of design factors on the frosting performance of a fin-tube heat exchanger is carried out using Taguchi method. The fin spacings of the heat exchanger are selected as design factors. Optimum values of the design factors under operating conditions of a household refrigerator/freezer are proposed. The average heat transfer rate and operating time of the optimum models, compared to those of a reference model, are increased at most by $6.5\%$ and $12.9\%$, respectively.

난류 유동 하에서 덕트 내의 착상

양동근,이관수,Yang, Dong-Keun,Lee, Kwan-Soo 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.8

A mathematical model considering the air side and the frost layer is presented to predict the frost layer growth. The standard k-$\varepsilon$ model for the air flow and the diffusion and energy equations for the frost layer are employed. The numerical results are compared with experimental data to validate the present model, and agree well with experimental data within a maximum error of 10%. The present model predicts well the frost properties and heat and mass transfer with respect to the frosting time. The variation of total heat transfer strongly depends on the operating condition, and has a similar trend to that of the sensible heat transfer. The frost properties along the flow direction are also investigated.

난류 모델을 이용한 서리층 성장 예측

양동근(Dong-Keun Yang),이관수(Kwan-Soo Lee) 대한기계학회 2002 대한기계학회 기타 간행물 Vol.2002 No.11

착상조건하에서 휜-관 열교환기의 성능 해석

양동근(Dong-Keun Yang),김민수(Min-Soo Kim),이관수(Kwan-Soo Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5

This paper presents a mathematical model o predict the thermal performance on a fin-tube heat exchanger under frosting condition. Empirical correlations of average heat transfer coefficients for the cold plate and tube surfaces and a diffusion equation inside the frost layer are employed in order to predict the frost layer growth. The numerical results are compared with experimental data for the frost growth and heat transfer to validate the present model. The results agree well with experimental data, and show that this model can be applied to evaluate the frosting performance of common fin-tube heat exchanger.

냉각 평판에서 서리 성장 모델링

양동근(Dong-Keun Yang),이관수(Kwan-Soo Lee) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4

This paper presents a mathematical model to predict the frost properties and heat and mass transfer within the frost layer formed on a cold plate. The laminar flow equations for the air-side are analyzed, and the empirical correlations of local frost properties are employed in order to predict the frost layer growth. The correlations of local frost density and effective thermal conductivity of frost layer. obtained from various experimental conditions. are derived as functions of various frosting parameters (Reynolds number. frost surface temperature. absolute humidity and temperature of moist air. cooling plate temperature. and frost density). The numerical results arc compared with experimental data and the results of various models to validate the present model, and agree well with experimental data within a maximum error of 10%. The heat and mass transfer coefficients obtained from the numerical analyses are presented, as the results. it is found that the model for frost growth using the correlation of heat transfer coefficient without solving air flow have a limitation in its application.

착상 조건하에서 휜-관 열교환기의 최적설계

양동근(Dong-Keun Yang),김민수(Min-Soo Kim),이관수(Kwan-Soo Lee) 대한설비공학회 2005 대한설비공학회 학술발표대회논문집 Vol.2005 No.6

원관 표면에서의 서리층 물성치의 상관식

양동근(Dong-Keun Yang),김민수(Min-Soo Kim),이관수(Kwan-Soo Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5

In this paper, frosting experiments are conducted with variations of frosting parameters such as the air temperature, cold cylinder surface temperature, air velocity, and absolute humidity. Experimental results show that the local frosting behavior with increasing air velocity does not vary along the angular position. The dimensionless correlations for the thickness, density, and surface temperature of the frost layer and heat transfer coefficient are obtained as functions of the Reynolds number, Fourier number, absolute humidity, and dimensionless temperature by using a dimensional analysis. The applicable range of the correlations proposed in this paper is as follows: the air temperature of 3 to 9℃, cold cylinder surface temperature of -32 to -20℃, are velocity of 0.5 to 2.0 ㎧, and absolute humidity of 0.00282 to 0.00568 Kg/Kga.

고분자를 이용한 자가치유 아스팔트에 관한 연구

양동근 ( Dong Geon Yang ),유평준 ( Pyeong Jun Yoo ),홍영근 ( Young Keun Hong ) 한국고무학회 2014 엘라스토머 및 콤포지트 Vol.49 No.2

자가치유형 아스팔트를 구현하기 위하여 분자간결합력이 큰 고분자를 아스팔트에 투입시켰다. 사용된 고분자 는 셜린, 나일론 및 폴리에스터이다. 이 고분자들은 가공온도가 200℃를 넘어 고체상태로는 투입이 어려워 용액상태로 첨가하였다. 고분자가 첨가된 아스팔트들은 우수한 개질효과와 치유효과를 나타내었다. 인장강도에서 고분자개질아스 팔트들은 고분자가 5% 투입되었으나 강도는 18%이상 증가하였다. 고분자와 아스팔트분자 간에 상호작용이 있는 것으로 보인다. 특히 셜린과의 분자간결합력이 가장 큰 것으로 보인다. 셜린은 아스팔트와 수소결합 및 아스팔트내에 존재하는 금속들과 이온결합을 할 것이다. 치유성에 있어서는 인장강도 면에서 셜린이 가장 높은 138%의 치유능을 나타내었으며 복합모듈러스 면에서는 폴리에스터가 141%의 치유능을, 충격강도 면에서는 나일론이 131%의 치유능을 보였다. 이는 치유능 해석에서 고분자의 분자간결합력도 중요 사항이지만 고분자와 아스팔트간의 상호작용 또한 중요한 고려 사항이 되어야함을 의미한다. Polymers are introduced to neat asphalt to prepare self-healing asphalt. The polymers are Surlyn, Nylon and polyethyleneterephtalate(PET). Since they are known as having high intermolecular force, they have high processing temperature. Therefore they are hardly introduced into the asphalt as bulk state. So in this study, they are introduced as solutions. Polymer-modified asphalts showed excellent modification effect and also healing effect. 5% polymer added asphalt showed more than 18% increased tensile strength. This tensile strength increment can be explained by polymer`s intermolecular forces. Especially Surlyn interacts with asphalt molecules by hydrogen bonding and also with metals in asphalt by ionic bonding. When it comes to healing aspect the healing efficiency of Surlyn increased to 138% based on tensile strength. That of PET increased to 141% based on complex modulus and in case of Nylon it increased to 131% based on impact strength. This tells that in dealing with healing efficiency the important considering factors are not only the intermolecular forces of the polymers but also the interaction between the polymer and asphalt molecules.

냉각평판에 형성된 서리층의 물성치

김성곤,양동근,이관수,Kim, Sung-Gone,Yang, Dong-Keun,Lee, Kwan-Soo 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.3

This paper proposes dimensionless correlations predicting properties of the frost layer formed on a cold flat surface. Experiments are carried out to obtain the correlations with various environmental parameters such as air temperature, air velocity, absolute humidity, and cooling plate temperature. As a result, the frost properties (frost layer thickness, density, surface temperature, thermal conductivity) are correlated as a function of Reynolds number, Fourier number, absolute humidity and non-dimensional temperature by using a dimensional analysis. The correlations agree well with the previous and our experimental data within a maximum error of 10%, and are used to predict the frost properties in the following ranges: Reynolds number of 20216 to 53763, Fourier number of 0.1962 to 2.5128, absolute humidity of 3.22 to 8.47, and non-dimensional temperature of 0.125 to 0.5.

원관의 냉각면에서의 착상

이동훈(Dong-Hoon Lee),양동근(Dong-Keun Yang),이관수(Kwan-Soo Lee) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4

This paper presents a semi-empirical model to predict the frost growth formed on the cold cylinder surface. The model is composed of the correlations for frost properties including the various frosting parameters and local heat transfer coefficient. The effects of varying the correlations for local heat transfer coefficient on the frost growth are examined to establish the model. The numerical results are compared with experimental data obtained by the previous researchers. The results agree well with the experimental data within a maximum error of 13%. As the results, the frost thickness decreases with changing angular position from front stagnation to separation point. Also the effects of air velocity on the frost growth are negligible, as compared to the other frosting parameters.