• Explosives and Blasting
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• v.18 no.3
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• pp.59-66
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• 2000

"Air Tube" 발파공법에 대한 연구는 기존의 일반 발파 방법의 단점을 크게 보완하여, 이 에 따른 진동, 폭음(소음), 전석 발생 등 이러한 문제점들을 해결하기 위해 고안된 것으로 기존 Air Decking 기술을 응용한 것이다. 본 연구는 폭약의 하부, 폭약과 폭약사이, 폭약의 상부와 전색 사이에 일정 길이의 "Air Tube"를 장착시켜 폭약의 투사면적을 증가시키고, 진동의 감쇠와 전석이 감소되어 특히 도심지에서 발생하는 민원의 대상이 될 수 있는 진동 및 폭음도 크게 줄일 수 있는 효과적인 발파 기술이다.일 수 있는 효과적인 발파 기술이다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.3
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• pp.292-301
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• 2000

This study experimentally investigates an air-side performance of oval tube heat exchanger against round tube heat exchanger using scaled-up model experiment for home air conditioners. A plain fin and round tube heat exchanger with 21 FPI(fins per inch) was used as a reference heat exchanger, and these were applied equally to 4 oval tube heat exchangers. Oval tube samples were designed with the same perimeter as 7.5mm diameter round tube, and their aspect ratios were 1:2, 1:3, respectively. In this study, the heat transfer and pressure drop characteristics of oval tube heat exchangers against round tube heat exchanger were also compared to one another, and an optimal samples for home air conditioners was recommended. And, general performance characteristics for an optimum oval tube samples chosen in this work was compared with round tube heat exchanger.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.11
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• pp.1020-1030
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• 2000

A crossflow finned tube evaporator has been investigated using tube-by-tube method. The refrigerant flows inside tubes while the air passes outside the finned tue. R134a for a refrigerant and wet air were used in this analysis. Three refrigerant circuitries, complex or simple, were compared. The effects of refrigerant circuitry and airside condensation on thermal performance such as heat transfer rate, enthalpy of refrigerant, temperature of refrigerant and air, pressure of refrigerant and average condensate layer thickness were investigated. It was found that this method could be applied to the analysis of finned tube evaporator for dehumidification and air conditioning.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.4
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• pp.499-510
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• 1999

A computer program was developed for simulating performance(capacity, power consumption and etc.) of air-conditioners using compressor, fin-tube heat exchanger and capillary tube. The program consists of five modules, condenser, evaporator, compressor, capillary tube simulation modules and properties modules of refrigerant and moist air, The present program is focused on R22 only, however can be easily extended for other refrigerants such as R407C and R410A just by adding property modules. The compressor simulation module utilizes performance maps supplied by manufacturers-map-based model. The condenser and evaporator simulation modules are modeled using tube-by-tube method. Simulation results(capacity and power consumption) were compared with calorimeter test results of actual air-conditioners of window and split types, where more than 82% of the data lied within ${\pm}5$% of the predicted results.

• Journal of the Korean Society of Safety
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• v.14 no.1
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• pp.3-9
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• 1999

The vortex tube is a simple device which splits a compressed gas stream into a cold stream and a hot stream without any chemical reactions. Recently, vortex tube is widely used to local cooler of industrial equipments and air supply system. In this study, the insulation effect of surface on the efficiency of vortex tube was performed experimentally. The experiment is carried out for nozzle area ratio of 0.194, diameter ratio of cold end orifice of 0.6 and input pressure ranging from 0.2Mpa to 0.5Mpa. The purpose of this study is focused on the effect of surface insulation of vortex tube with the variation of cold air mass flow ratio. The results indicate that the temperature difference of cold and hot air are higher about 12% and 30% than that of not insulated vortex tube respectively. Furthermore, for the insulated vortex tube, the similarity relation for the prediction of cold end temperature as the function of cold air mass flow ratio and input pressure is obtained.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.1
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• pp.23-30
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• 2005

The air-jet loom represents a major step in the development of shutterless weaving due to its ability to weave a wide range of yarns at high speeds. The air-jet weaving involves inserting a pre-measured length of yarn through the wraps, which is shed by means of compressed air. The analysis of air flow characteristic of the main nozzle and acceleration tube is required for improving the loom performance. In this paper, we examined the effects of the main nozzle with different acceleration tubes as well as diameters. Also, we compared the performance of a straight-type tube with a Laval-type tube and the effect of installing a suction hole on the acceleration tube.

• Journal of ILASS-Korea
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• v.8 no.2
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• pp.16-23
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• 2003

The Air-jet loom represents a major step in the development of shutterless weaving due to its ability to weave a wide range of yarns at high speeds. The Air-jet weaving involvers, inserting a pre-measured length of yam through the wrap, is sheds by meads of compressed air. The analysis of air flow characteristic of the main nozzle and acceleration tube is required for the loom performance. h this paper We examined the effect of the main nozzle with different acceleration tubes as well as diameters. And also, we compared the performance of straight type tube with laval type tube and of according to be suction hole on the acceleration tube, respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.9
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• pp.818-826
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• 2001

In this study, in-situ performance test of a wet surface finned-tube evaporator of an air source heat pump which has a rating capacity of 20RT is carried out. Since test conditions, such as indoor and outdoor air conditions cannot be controlled to satisfy the standard test conditions, experiments are done with the inlet air conditions as they exist, From the experimental data, air side heat and mass transfer coefficients were calculated by the well known heat and mass transfer analogy and tube-by-tube method. since current procedure underpredicted the experimental sensible heat factor(SHF), a proper empirical parameter was introduced to predict the experimental data with satisfactory results. This study provides the method of evaluating the heat and mass transfer coefficients of a wet surface finned-tube evaporator of which in-situ performance test in necessary.

• International Journal of Air-Conditioning and Refrigeration
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• v.10 no.4
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• pp.211-219
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• 2002

In this study, in-situ performance test of a wet surface finned-tube evaporator of an air source heat pump which has a rating capacity of 20 RT is carried out. Since test conditions, such as indoor and outdoor air conditions cannot be controlled to satisfy the standard test conditions, experiments are done with the inlet air conditions as they exist. From the experimental data, air side heat and mass transfer coefficients were calculated by the well known heat and mass transfer analogy and tube-by-tube method. Since current procedure underpredicted the experimental sensible heat factor (SHF), a proper empirical parameter was introduced to predict the experimental data with satisfactory results. This study provides the method of evaluating the heat and mass transfer coefficients of a wet surface finned-tube evaporator of which in-situ performance test is necessary.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.73-81
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• 2008

Intercooling and aftercooling are required in order to operate air compressor, these are conducted through air-cooled or water-cooled heat exchangers. This study aims to find more suitable type of heat exchanger as a water-cooled intercooler of air compressor. Comparative performance evaluation among fin-tube heat exchanger and shell-and-tube (S&T) heat exchanger having various tubes such as circular tube, spiral tube, and internally finned tube was conducted. Thermal-hydraulic performance of each heat exchanger type is evaluated in terms of temperature drop and pressure drop. The comparisons show that shell-and-tube heat exchangers may have similar and larger heat transfer capacity to the fin-tube heat exchanger if tube diameter is reduced and multiple pass is adopted. For these cases, however, compressed air pressure drop in shell-and-tube heat exchanger become much larger than that in fin-tube heat exchanger.