• 설비공학논문집
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• 제14권8호
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• pp.617-625
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• 2002

In this study, effects of refrigerant and oil charges on the performance of a refrigeration system simulating an automobile air conditioner have been experimentally investigated using R134a and PAG oil. Measurements were taken in a breadboard type refrigeration test unit with a compressor used for a commercial automobile air-conditioner under a set of condition imposed upon normally to automobile air conditioners. Both the COP and capacity decreased rapidly as the oil charge increased because of the decrease in vapor pressure of the circulating refrigerant/oil mixture. The excess oil left in the evaporator also caused heat transfer degradation resulting in a decrease in capacity and in turn COP. It was found that there is an optimum refrigerant charge at which the COP becomes the maximum. Below this optimum charge, both the capacity and COP increased as the refrigerant charge increased and above the optimum charge, both of them remained almost constant. Hence, the COP seems to be the most important factor in determining the optimum refrigerant charge. When the system was undercharged, the refrigerant at the condenser exit lost subcooling and showed a sign of poor miscibility.

• 설비공학논문집
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• 제10권3호
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• pp.292-302
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• 1998

In this study, 14 refrigerant mixtures composed of R32, R125, R134a, R143a, R152a, and R1270(Propylene) were tested in a breadboard heat pump in an attempt to replace R22 used in most of the residential air conditioners and heat pumps. The heat pump was of 1 ton capacity and water was employed as the secondary heat transfer fluids. All tests were conducted under ARI test A condition. Ternary mixtures composed of R32, R125, and R134a were shown to have 4∼5% higher COP and capacity than R22 and hence they seem to be very promising candidates to replace R22. On the other hand, ternary mixtures containing R125, R134a, and R152a have lower COP and capacity than R22. R32/R134a binary mixtures show a 7% increase in COP and have the similar capacity to that of R22 and hence they are also good candidates to replace R22. Special care must be exercised when a suction line heat exchanger is used with these mixtures in air conditioners. Finally, the compressor discharge temperatures of all mixtures tested were lower than those of R22 by 15.g∼34.7t, which indicates that these mixtures would offer better system reliability and longer life time than R22.

• 설비공학논문집
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• 제10권3호
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• pp.315-323
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• 1998

This paper contains a verification of simulation program to predict the capacity of a condenser used in car air-conditioners. Verification of simulation program is carried out with the comparison error between experiment and simulation bounds within 3.5%. The present investigation shows the results for heat transfer rates of condenser under different operating conditions, such as velocity and degree of superheat. The range of front velocity of air is 1∼5m/s. As the front velocity is increased, the heat transfer rate of condenser is largely increased at a low velocity range. In a meanwhile, heat transfer rate of condenser is almost constant in a range of velocity over 3m/s. As for the effect of inlet pressure of refrigerant on the heat transfer rate, we obtained the similar trend of heat transfer rates as like varying the front velocity, Also we have calculated the heat transfer rates with varying inlet superheats of refrigerant, the larger the superheat is, the more heat transfer rate is obtained.

• 설비공학논문집
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• 제24권6호
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• pp.467-475
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• 2012

Recently, residents have been spending almost 90% of their time indoors, which presents a higher risk from inhalation of pollutants than when spending time outdoors. Therefore, controlling indoor air quality became important. It is reported that the lung diseases and mortality for occupants are increased when there is high density of ozone which is one of the pollutants among the indoor air. In addition, the reactions between ozone and building materials produce VOCs and formaldehyde. The studies to eliminate the ozone by building materials have been actively investigated. However, ozone removal and secondary pollutants from ozone reactions with building materials have not been reported in Korea. For this reason, the aim of this study is to introduce ozone removal by HVAC filters, various building materials, and eco-friendly building materials including the quantity of secondary pollutant emissions.

• 설비공학논문집
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• 제22권9호
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• pp.641-647
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• 2010

Ground-source(Geothermal) heat pump(GSHP) systems can achieve a higher coefficient of performance than conventional air-source heat pump(ASHP) systems. However, GSHP systems are not widespread because of their expensive installation costs. The authors have developed a GSHP system that employs the cast-in-place concrete pile foundations of a building as heat exchangers in order to reduce the initial cost. In this system, eight U-tubes are arranged around the surface of a cast-in-place concrete pile foundation. The heat exchange capability of this system, subterranean temperature changes and heat pump performance were investigated in a full-scale experiment. As a result, the average values for heat rejection were 186~201 W/m(per pile, 25 W/m per pair of tubes) while cooling. The average COP of this system was 4.6 while cooling; rendering this system more effective in energy saving terms than the typical ASHP systems.

• 설비공학논문집
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• 제25권1호
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• pp.14-19
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• 2013

The present study has been conducted for evaluating and comparing the performance of the underfloor air distribution system(UFAD) and the ceiling based air distribution system(CBAD) under cooling condition. Simulations and experiments were carried out for verifying the model by TRNSYS program about UFAD and CBAD. The results of simulation for various conditions of thermal load are summarized as followings. UFAD had an advantage for making thermal comfort because of lower temperature of the floor surface. Moreover, UFAD showed lower fan power about 30~50% than CBAD under the same conditions of thermal load. The energy saving rates of UFAD were increased to 17.7% in proportion to the thermal load on unoccupied zone(lighting). Ultimately, additional investigations should be done for analyzing optimized operating conditions of UFAD with considering the thermal performance of building envelop and the thermal load.

• 한국강구조학회 논문집
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• 제25권2호
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• pp.187-196
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• 2013

CFT구조의 기둥-보 접합부는 강관의 국부좌굴을 방지하기위해 다이아프램이 필요하다. 외측다이아프램 형식은 관통다이아프램 형식보다 콘크리트의 충전성이 좋으나 시공성과 건축설비와 공조하는 측면에서 불편함이 있다. CFT구조 접합부의 상부 다이아프램은 외측다이아프램 형식으로 하고 하부 다이아프램은 관통다이아프램 형식으로 하였다. 이것은 건축물에서 바닥슬래브가 있으므로 상부 다이아프램은 바닥슬래브와 일체가 되고 하부 다이아프램으로 관통다이아프램을 적용하여 건축설비와의 마찰을 피하고자 한 것이다. 결과적으로 충전성을 개선시킨 CFT구조의 구조성능은 상, 하부 모두 관통다이아프램을 적용한 구조와 비교하면 동일하다는 것을 알 수 있다.

• 설비공학논문집
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• 제16권10호
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• pp.914-922
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• 2004

In this study, measurement and analysis of energy consumption of a research building have been conducted. The energy audit procedure includes monitoring of electricity and LNG consumption over a period of three yews from 2000 to 2002. Data acquisition system for collecting energy consumption data of HVAC equipment such as chillers, fan filter units, AHUs, cooling towers, boilers, pumps, fan coil units, air compressors and etc. has been installed in a building located in Seoul. Data collected at an interval of 1 minute are analyzed for studying the energy consumption pattern of a research building. Percentage of energy consumption of all HVAC equipment is $51.0\%$ in 2000, $55.4\%$ in 2001, and $62.3\%$ in 2002, respectively. Electricity consumption of chillers accounts for $17.6\%$ of the total energy consumption, which is the largest. Annual energy consumption-rate per unit area is $840.5Mcal/m^2{\cdot}y$ in 2000, $1,064.8Mcal/m^2{\cdot}y$ in 2001, and $1,393.0Mcal/m^2{\cdot}y$ year 2002, respectively.

• 설비공학논문집
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• 제16권10호
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• pp.932-941
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• 2004

The objective of this study is to detect the multi-fault of HVAC system using a new pattern classification technique. To classify the effect of single-fault in determining the pattern, supply air temperature, OA-damper, supply fan, and air flowrate were chosen as experimental parameters. The combination of supply temperature, flow rate, supply fan and OA-damper were chosen as multi-fault conditions. Three kinds of patterns were introduced in the analysis of multi-fault problem. To solve multi-fault problem, the new pattern classification technique using residual ratio analysis was introduced to detect the multi-fault as well as single-fault. The residual ratio could diagnose single-fault or multi-fault into several patterns.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.325-330
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• 2006

Modern people spend more and more time in an automobile in their daily life. In this life, drivers and passengers should create HVAC environment in the automobile interior which is not only for convenient transportation but also give comfortable feeling with dwelling culture. Also, the latest cars give much importance for the role of HVAC system that controls the environment of the area for passengers more than just basic capability. There are solar radiant heat, surface temperature, refrigeration system(temperature, humidity, air current, velocity), and dust for the factor which have an effect on the HVAC environment in the automobile interior, also these are being carried for the HVAC environment delivered an individual character. In this study, we drew the automobile interior as three dimension and arranged a method of numerical analysis on HVAC environment in the automobile interior displaying air current distribution and temperature distribution through simulation of the automobile interior on the ventilation volume and outlet area. The aim of this study is to develop the estimated method for HVAC environment. in the automobile interior.