• 수산해양교육연구
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• 제26권6호
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• pp.1392-1401
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• 2014

This study was conducted to understand elementary school from third to sixth grade students' conceptions of evaporation and condensation to classified by grade and examples of questionnaires. For this purpose, 1606 students from 3rd grade to 6th grade were involved. They had conceptions of evaporation and condensation questionnaire. The results of this study were as the following: Firstly, students have to know about the basic conceptions to understand conceptions of evaporation and condensation. Secondly, it would appear that these ideas can sometimes be influenced in unintended ways and be not easily changed by science teaching. Thirdly, it would appear that they understood conceptions of evaporation better than that of condensation.

• 한국초등과학교육학회지:초등과학교육
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• 제17권1호
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• pp.89-103
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• 1998

We study that what kind of the concepts of evaporation and condensation students of elementary school have. The results are following. (1) The students have simple concepts of evaporation on natural circumstance. However, they don't understand about various effect on evaporation. (2) They don't know where the evaporized water is comming from. (3) They have experiences on observing condensation of wale. (70%), however don't know that the water is evaporized in the air. (4) They have more understanding about evaporation, more correct concepts on condensation in circulation of water.

• 대한기계학회논문집B
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• 제20권5호
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• pp.1725-1734
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• 1996

Experimental condensation and evaporation heat transfer coefficients were measured in a horizontal smooth tube and a horizontal micro-finned tube with HFC-134a. The test sections are straight, horizontal tubes with have a 9.52mm outside diameter and about 5000mm long. The micro-finned tube had 60 fins with a height of 0.12mm and a spiral angle of 25.deg.. The condensation test section was a double-pipe type with counter flow configuration. The evaporation test section employed an electic heating method. Enhancement factors which is defined as a ratio of the heat transfer coefficient for micro-finned tube to that for smooth tube, varied from 1.3 to 1.6(mass flux:110~190kg/m$^{2}$s) for condensation and 1.2 to 1.5 (mass flux:70~160kg/m$^{2}$s) for evaporation. The experimental data of condensation and evaporation heat transfer coefficients were compared to several empirical correlations. Based on these comparisons, modified correlations of the condensation and evaporation heat transfer coefficient for both smooth and micro-finned tubes were proposed.

• 한국과학교육학회지
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• 제14권3호
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• pp.272-284
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• 1994

The aim of this research was to compare and analyze the children's ideas on evaporation and condensation between pre- and post-intervention. Forty-eight children from six elementary schools in Seoul and Kyung Ki provinces were sampled by stratified random sampling. A set of structured activities was then provided which allow children to explore evaporation and condensation phenomena. All of these activities had a preliminary phase which required the child to predict or speculate on evaporation and condensation using their existing knowledge. These structured activities on evaporation and condensation were reviewed by three professors and eigth primary school teachers. Their comments were used to revise the original contents of the structured activities. The data analysed were gathered by the questionaire and the interview. Pre- and post-intervention data related to evaporation and condensation were collected by the same teacher, and analysed into the same category scheme. Data coding was carried out several times by the researcher to ensure reliablity. Data collected were then classified and analyzed according to the types of children's ideas. The findings of this study were as follows: Results of this study showed that the the vocabulary used to describe the evaporation phenomena varied according to the context, and the scientific term "evaporated" was more frequently used by the older children after post-intervention. But everyday terms such as"dried up","disappered", "gone up" were also used by children as much as the level of pre-intervention. Scientific conception on the location of evaporated water, the factor of evaporation, the ideas about getting the water back and assumption about the physical state of the missing water has been increased for the most of the children after intervention. It was found that the intervention using was effective SPACE strategies regardless of the grade level of the children.

• Journal of Advanced Marine Engineering and Technology
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• 제36권5호
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• pp.580-585
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• 2012

R744용 해양온도차 발전 시스템의 작동변수에 대한 기초 설계자료를 제공하고자 증발열량, 응축열량, 전체일량, 효율에 대한 사이클 성능을 분석하였다. 본 연구에서 고려된 작동변수는 R744 해양온도차 발전 사이클의 과열도, 과냉각도, 응축온도, 증발온도 등이다. 주요 결과를 요약하면 다음과 같다. R744의 증발열량은 과열도와 과냉각도가 증가할수록 증가하는 반면, 응축온도가 증가할수록 감소한다. 전체일량은 R744의 과열도와 과냉각도와 함께 증가하나 증발온도는 증가할수록 감소한다. 그리고 효율은 과열도와 과냉각도가 증가할수록 증가하는 반면, 응축온도는 감소한다. 그러므로 R744용 해양온도차 발전 시스템의 증발열량, 응축열량, 전체일량, 효율은 과열도, 과냉각도, 응축온도, 증발온도, 펌프와 터빈 효율에 영향을 받는 것을 알 수 있었다. 따라서 R744용 해양온도차 발전 시스템의 설계시에는 이러한 영향을 면밀하게 파악하여야 한다.

• 대한기계학회논문집B
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• 제32권8호
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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.

• 한국입자에어로졸학회지
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• 제12권4호
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• pp.135-143
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• 2016

Removal of water contents in a gas is needed in industrial field of gas processing related on energy production/conversion, and environmental treatment. Inertial separators are economic devices for separating droplets from the gas stream. For accurate understanding of removal process in a curved vane mist eliminator, a numerical model including turbulent dispersion, evaporation and condensation of water vapor at surface of droplets is required. A two-stage curved vane mist eliminator has been modeled, and fluid flow of mixture of air and water vapor and droplet trajectories were solved simultaneously with taking into account two-way coupling. Removal efficiency of droplets with various inlet condition of relative humidities (RH, 40%, 90%, and 100%) were compared. As RH increased, the effect of evaporation decreased and inertial separation efficiencies of droplets obtained increased especially for droplets of diameter below 10 micrometers.

• 동력기계공학회지
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• 제17권3호
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• pp.44-49
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• 2013

The refrigerating system are high efficiency and comfortable due to the automation of the system as well as enhance energy saving are contributing to driving system. Previous study the rotational frequency of the compressor was confined to the fixed condition have changed load of evaporator and condenser related about the refrigerator performance characteristic according to the evaporation load and condensation load change tries to be analyze through the experiment. The useful data for the economic driving of the freezing apparatus tries to be drawn. Consequently, it confirmed that refrigerant in the compressor overheated and as the evaporation load increased the specific volume was increased and the coolant circulation rate decreased. In confirmed that condensation load increased the compression ratio and discharge gas temperature increased. It reduced the low-temperature efficiency and condensation calorie and the quality factor was decreased.

• 한국과학교육학회지
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• 제13권1호
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• pp.92-99
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• 1993

The purpose of this study was to investigate and analyze the conception of elementary school students on evaporation and condensation, and then to verify the types of the conception. Forty-eight children from six elementary schools were sampled by stratified random sampling in Seoul and other provinces. They responded to the questionaire and the interview. This study was carried out according to the process of the basic study, the preliminary study, and the main study. The materials collected were classified and analyzed according to the types of children's ideas. The findings of this study were as follows. 1. The vocabulary used to describe the evaporation phenomena varied according to the situations, and the scientific term "evaporation" was more frequently used by the older groups. 2. Most children answered that the last location of water were air/sky/cloud. Air/cloud which represents the scientific conception of the location of water were mentioned by children of all ages. The higher the grade of the children were, the more scientific conception the children mentioned, however. 3. Most children referred to the heat as the factor of evaporation. Wind, on the other hand was mentioned by less than 10% of lower graders, and by about 30% of higher graders. 4. The result of asking children whether they thought it was possible to get the evaporated water back showed that about 70% of lower graders denied the possibility of the water being reversible. About 60% of higher graders. however, recognized that the water will be returned as rain or condensation. This increase may be associated with formal teaching of water cycle. 5. In the ideas of evaporation and condensation, some of the children have supernatural ideas and animism, which are most younger chilren's characteristics.

• 연구논문집
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• 통권30호
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• pp.15-23
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• 2000

In this study, develop the thermal pump using water evaporation and condensation. Vapor from heating room moves up to pumping room and press the water of pumping room. Consequently water is pumped out to water tank. Then hot vapor direct contact with cold water in condensing room after pumping process. At this time, pressure of condensing room is down to-5kPa and suck in water of tank. This pump executes self ping and good durability because of no mechanical moving parts. Thermal pump is pumped cyclic so that, this pump is not used single. Therefore thermal pump of hot water boiler used to multi-stage for stable pumping rate. As the result of performance test, the developed thermal pump proves pumping action of water evaporation/condensation. And total volume flow rate is 500liter during one hour. If three thermal pump is installed parallel, this pump can use to the hot water boiler in the 300,000kcal/h class.