• Journal of Mechanical Science and Technology
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• v.19 no.8
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• pp.1649-1661
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• 2005

We consider. a horizontal static liquid layer on a planar solid boundary. The layer is evaporating when the plate is heated. Vapor recoil and thermo-capillary are discussed along with the effect of mass loss and vapor convection due to evaporating liquid and non-equilibrium thermodynamic effects. These coupled systems of equations are reduced to a single evolution equation for the local thickness of the liquid layer by using a long-wave asymptotics. The partial differential equation is solved numerically.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.8
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• pp.621-628
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• 2008

A numerical study for the flow, heat and mass transfer characteristics of the evaporating tube with the films flowing down on both the inside and outside tube walls has been carried out. The condensation occurs along the outside wall while the evaporation occurs at the free surface of the inside film. The transport equations for momentum and energy are parabolized by the boundary-layer approximation and solved by using the marching technique. The calculation domain of 2 film flow regions (evaporating and condensation films at the inside and outside tube wall respectively) and tube wall is solved simultaneously. The coupling technique for the problem with the 3 different regions and the 2 interfaces of them has been developed to calculate the temperature field. The velocity and temperature fields and the amount of the condensed and evaporated mass as well as the position where the evaporating film is completely dried out are successfully predicted for various inside pressures and inside film inlet flow rates.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.789-798
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• 1999

The evaporating heat transfer experiments with refrigerant HCFC 22 are performed for performance evaluation using 4 and 6 kinds of microfin tubes with outer diameter of 9.52mm and 7.0mm, respectively. Used microfin tubes have different shape and number of fins with each other, The experimental results are represented with effects of quality, mass flux and EPR. The evaporating heat transfer characteristics are represented by the existence of not only heat transfer area and turbulence promotion effect but also additional other enhancement mechanism, which are the overflow of the refrigerant over the microfin and microfin arrangement. Microfin tubes having a shape which can give much overflow over the microfin show large evaporating heat transfer coefficients. The effect of refrigerant overflow is much severe in evaporation than condensation. The effect of microfin arrangement is related to overflow effect of the refrigerant over the microfin.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.05a
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• pp.156-159
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• 2006

In order to design an evaporation system, geometric simulation of film thickness distribution profile is required. In this paper, a geometric modeling algorithm is introduced for process simulation of the evaporating process. The physical fact of the evaporating process is modeled mathematically. Based on the developed method, the thickness of the thin-film layer can be successfully controlled.

• International Journal of Air-Conditioning and Refrigeration
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• v.14 no.3
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• pp.102-109
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• 2006

Experimental results for heat transfer characteristics and pressure gradients of HCs refrigerants R-290, R-600a, R-1270 and HCFC refrigerant R-22 during evaporating inside horizontal double pipe heat exchangers are presented. The test sections which has one tube diameter of 12.70 mm with 0.89 mm wall thickness, another tube diameter of 9.52 mm with 0.76 mm wall thickness are used for this investigation. The local evaporating heat transfer coefficients of hydrocarbon refrigerants were higher than that of R-22. The average evaporating heat transfer coefficient increased with the increase of the mass flux, with the higher values in hydrocarbon refrigerants than R-22. Hydrocarbon refrigerants have higher pressure drop than R-22. Those results from the investigation can be used in the design of heat exchangers using hydrocarbons as the refrigerant for the air-conditioning systems.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.134-139
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• 2000

Evaporating heat transfer characteristics of R-22 were measured inside smooth horizontal copper tubes with inner diameters of 3.36 mm and 5.35 mm respectively. The experiments were conducted in the closed loop which was driven by a magnetic gear pump. Experiments were performed for the following range of variables ; mass velocity of refrigerants (200 to 400 $kg/m^2$ .s) saturation temperature ($0^{\circ}C, \; 5^{\circC$}) and quality (0 to 1.0) The main results obtained are as follows : Evaporating heat transfer coefficients in the small diameter tubes (ID<7 mm) were observed to be strongly affected by a variety of diameters and to differ from those in the large diameter tubes. The heat transfer coefficients of the small diameter tubes are higher than those of the large diameter tubes. Comparing the heat transfer coefficients between experimental results and some well-known previous predictions (Shah's correlation Gungor-Winterton's and Kandlikar's correlation) it was very difficult to apply those to small diameter tubes.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1405-1414
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• 1993

The purification of sewage deriving from agricultural and food industries is today a serious problem mainly in areas characterized by intensive production plants. The solution examined in this work, involves a system of natural evaporation which employs special panels with a large evaporating surface constituted by an internal cellular structure in polyethilene. Using renewable energy they allow to speed up the natural evaporating effect thus eliminating some drawbacks such as swamps and obtaining sewage concentration with relatively low costs. The institute of agricultural engineering has carried out tests on the disposal of sewage deriving from two very important production sectors; pig-breeding and olive oil production . at a were gathered in order to verify the operating capacity of plants and their variables . On the remaining concentrated part tests were also carried out in order to know its chemical and chemical-physical features and to study the possibility for its us .

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.7
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• pp.564-571
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• 2001

The present study investigated the effect of key parameters on the performance of a cascade system using R-22 and R-23 refrigerants. Experimental data for the cascade system have been compared with simulation results using thermodynamic analysis. The cascade system tested at the evaporating temperature of $-80^{\circ}C $ and the condensing temperature of$40^{\circ}C $. The key experimental parameters were the evaporating temperature of the HTC(-35, -30, -25, -20, $-15^{\circ}C $) and mass flux of the HTC(200, 250, 300kg/$m^2$s). As the evaporating temperature and the mass flux of the HTC were increased respectively, the COP and the refrigerating efficiency were increased and then decreased while the volume flow rate per unit refrigeration capacity showed the opposite trend. The maximum COP and refrigerating efficiency were obtained at the evaporating temperature of the HTC of $-25^{\circ}C $ and the mass flux of 250 kg/$m^2$s.

• YAKHAK HOEJI
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• v.3 no.1
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• pp.51-55
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• 1957

It has been suggested that the fluorine content of crude sea salt may have special value in the prevention of tooth decay, by A.E.Schaefer and J/H/.Shaw. Shaw calculated that if crude sea salt containing about 40 ppm of fluorine were used, the consumption of 26-44 grams of the salt per day for each prison would be sufficient for the prevention of tooth decay. He also suggested that this level of salt consumption is actually quite common among many population in the far and near east. In order to examine the fluorine contents of sea salt in Korea, several kinds of solar-evaporating salt and pan-evaporating salt were studied. The experimental results may be summarized as follows; 1. Fluorine contents of 9 kinds of solar-evaporating salt ranged from 3.8 to 15.0 ppm and the average was 7.52 $\pm$ 3.89 ppm. 2. Fluorine contents of 7 kinds of pan-evaporating salt ranged from 2.5 to 7.1 ppm. 3. The more the salt is refined, the less becomes the fluorine content. 4. Even the crudest sea salt can not contain about 40 ppm of fluorine. 5. Statistically, daily consumption of sea slat for each person in Korea is 28 grams.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.63-64
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• 2006

Chracteristics on evaporating pressure drop of HCs refrigerants inside a horizontal tube were studied experimentally. Experimental results were presented for pressure drops of hydrocarbon refrigerants R-290, R-600a, R-1270 and HCFC refrigerant R-22 inside a horizontal double pipe heat exchanger. Three tubes with a tube diameter of 12.70mm, 9.52mm and 6.35mm were used for this study. Hydrocarbon refrigerants showed higher evaporating pressure drop than that of R-22 in all tubes. The highest pressure drop was founded in R-600a. The highest evaporating perssure drop of all refrigerants was shown in a tube diameter of 6.35mm with same mass flux. The results can be used as the basic data for the design of heat exchanger using hydrocarbon refrigerants as an alternatives.