• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.6
• /
• pp.665-671
• /
• 2004

A mathematical model is presented to predict the frost properties and heat and mass transfer within the frost layer formed on a cold plate. The model consists of the laminar flow equations for air-side and the empirical correlation of local frost density. The correlation of local frost density used in this study is obtained from various experimental conditions by considering frosting parameters. The numerical results are compared with experimental data to validate the model, and agree well with experimental data within a maximum error of 9%.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.8 s.227
• /
• pp.989-995
• /
• 2004

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.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.14 no.3
• /
• pp.261-267
• /
• 2002

The integral boundary layer equation for the air side and the diffusion equation for the frost layer are numerically analyzed in order to predict the behavior of frost layer growth. The thickness and density of the frost layer obtained from the present study agree well with those of previous numerical results and experimental data with a maximum error of 13%. The characteristics of heat and mass transfer within the frost layer and the frost layer growth along the flow direction are investigated by performing numerical analysis. The effects of operating conditions on the frost layer growth are also examined.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.3
• /
• pp.374-380
• /
• 2003

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.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.18 no.2
• /
• pp.122-128
• /
• 2006

In this paper, frosting experiments were conducted with variations of frosting parameters in order to obtain the correlations of frost properties. As a result, the local thickness, density, and surface temperature of the frost layer were presented. The dimensionless correlations for the frost thickness, frost density, frost surface temperature and heat transfer coefficient were derived as functions of dimensionless frosting parameters by using a dimensional analysis.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.11 no.3
• /
• pp.377-383
• /
• 1999

In this study, the behavior of frost formation according to surface characteristics in the fin-tube heat exchanger has been examined experimentally. The results show that the thickness of the frost which is attached to the hydrophilic heat exchanger becomes thin and the air pressure drop is smaller than that of bare aluminium heat exchanger However, the frost mass of hydrophilic heat exchanger is more than the bare one. Hence, high density frost is attached to hydrophilic heat exchanger. The sensible and latent heat flux of hydrophilic heat exchanger is bigger than that of bare one, but the increasing amount is very small and the improvement of thermal performance is also very small. The variation of fin-pitch of heat exchanger shows little influence on frost formation and hydrophilic heat exchanger loses its surface characteristics rapidly with increasing relative humidity.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1540-1545
• /
• 2004

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.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.11a
• /
• pp.65-66
• /
• 2017

Early-frost damages easily take place in smaller and thinner walls and slabs. In case of slabs, it is difficult to visually determine the depth of early-frost damage. As such, the current study aims to determine the depth of early-frost damage caused to concrete structures due to bad curing in the winter. As a result, the study found that the depth of early-frost damages increased from the top as the atmospheric temperature on the concrete surface decreased. The changes in the color allowed the observer to easily identify the depth of early-frost damage with the naked eye. In particular, the color difference between potentially damaged parts and undamaged parts were the greatest around thirty minutes of drying after wetting.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1999.11a
• /
• pp.211-216
• /
• 1999

One of the problems in a refrigerator operation is the frost formation on a cold surface of the evaporator. The frost layer is formed by the sublimation of water vapor when the surface temperature is below the freezing point. This frost layer is usually porous and formed on the cold surface of the evaporator. The frost layer on the surface of a evaporator will make side effect such as thermal resistance. However, these important factors have not been used in determining the defrosting period. In this report, a prediction taking into account the change of the fin efficiency due to the growth of the frost layer.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.3
• /
• pp.1096-1105
• /
• 1996

A theoretical model of the frost formation has been presented to investigate the characteristics of the growth of frost layer by considering molecular diffusion of water vapor and heat generation caused by sublimation of water vapor in the frost layer. The present model was compared with existing experimental data as well as a previous model. The difference between the present model and existing experimental data was found to be about 6 percent. An analysis for the behavior of frost formation using present model shows a good agreement with the trend for a number of experimentally observed features. The present analysis can also provide the physical understanding on the phenomena of the frost formation.