• 설비공학논문집
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• 제25권9호
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• pp.516-521
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• 2013

In the present study, the performances of a fin-tube evaporator and three PF evaporators for a heat pump dryer were experimentally investigated. Among the tested evaporators, the PF3 type evaporator showed the highest values of heat transfer capacity and dehumidification performance, while the fin-tube evaporator had the lowest values. PF3 showed better performance compared to PF1 and PF2, due to the large pin pitch, which leads to more draining for dehumidified water. Also, the $45^{\circ}$ inclined PF evaporator presented better performance than that of the $90^{\circ}$ inclined PF evaporator, owing to its easier draining characteristics. The effect of air velocity was revealed to be quite large. When the air velocity increased by 20%, the heat transfer capacity and dehumidification performance increased 43%/11%, 48%/13% and 54%/23% for PF1, PF2 and PF3, respectively.

• 설비공학논문집
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• 제20권1호
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• pp.11-16
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• 2008

Infrared (IR) detectors are widely used for such applications as thermoelastic stress analysis, medical diagnostics and temperature measurement. Infrared detectors commonly need to be refrigerated below 80 K, and thus a cooling system should be equipped together with the detector system. The cooling load, which should be removed by the cooling system to maintain the nominal operating temperature of the detector, critically depends on the insulation efficiency of the cryochamber housing the detector. Thermal load of a cryochamber is attributed to the conduction heat transfer through a cold finger, the gases conduction and radiation heat transfer. The thermal loads of an infrared detector cryochamber with a radiation shield are investigated experimentally in present study. Since the effect of radiation heat transfer on thermal loads is significant, radiation shields is installed in the cold finger part to protect heat input through radiation.

• 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.

• 설비공학논문집
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• 제17권6호
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• pp.552-559
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• 2005

This paper describes an experimental study on the inertance pulse tube refrigerator using a small compressor. The purpose of this experimental study is to identify the performance of the inertance pulse tube refrigerator for various operating conditions and to obtain the optimum configuration. The dead volume effect is verified by two experimental apparatuses with different dead volumes between the compressor and the aftercooler. The refrigerator of the smaller dead volume shows better performance. The influence of operating frequency and charging pressure on the performance of the refrigerator is experimentally investigated. Reducing the regenerator mesh size improves the performance of the refrigerator. Finally, the inertance pulse tube refrigerator has maximum cooling capacity at the specific combination of the pulse tube length and the inertance tube length. The loss analysis is used to analyze and predict the optimum condition of the pulse tube refrigerator.

• 설비공학논문집
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• 제17권6호
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• pp.581-586
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• 2005

Recently, the use of UVGI system has been increasing in both medical and nonmedical buildings for the control of environmental microorganisms. In the present study, irradiance performance test of UVC lamp was carried out and indoor air sterilization effect of UV ray for preventing transimission of air borne contagion was investigated by using manufactured UVC air sterilizer. Experimental results show that the effective irradiance of UVC lamp is strongly dependent on air velocity and temperature in irradiance performance test. An individual microbiological killing effectiveness experiment also shows that the average kill rate of two microbiological samples such as bacteria and fungus is about $92\%$ by using manufactured UVC air sterilizer. Additionally irradiance performance experimental results also show that the ballast is very important factor to keep up irradiance performance of UVC lamp.

• 설비공학논문집
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• 제17권6호
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• pp.529-535
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• 2005

This study experimentally examines the air-side performance of spiral finned tube heat exchangers. The effects of fin spacing, fin height, and tube alignment were investigated. Reduction of fin spacing decreased the Colburn j factor. However, the effect of fin height on the Colburn j factor was negligible. An increase of tube row decreased the Nusselt number for both staggered and in-line tube alignments. However, the decrease of the Nusselt number for the in-line tube alignment was much more significant than that of the staggered tube alignment. The average Nusselt number of the staggered tube alignment was larger than that of the in-line tube alignment by $10\%$ when the Reynolds number ranged from 300 to 1700. An empirical correlation of the Nusselt number was developed by using geometric parameters of heat exchanger and correction factors. The correction factor considered the effects of tube alignment and number of tube rows on the heat transfer. The proposed correlation yielded a mean deviation of $4\%$ from the present data.

• 설비공학논문집
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• 제12권1호
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• pp.75-82
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• 2000

This paper presents the predicted results by CFD technique of air flow and contaminant distribution in a full-scale kitchen opened to a living room, ventilated by a exhaust hood. To analyze the characteristics of the indoor environment, the concept of contaminant index was defined. In this study, the locations of the gas range and the window were chosen as the parameters to investigate the indoor environment. The values of the contaminant index for several layout of the gas range and the window were calculated and compared. When the gas range is installed along the wall with specified window location, its position in relation to the wall has unnoticed effect on contaminant infer. Once the location of the gas range is fixed, the indoor air quality may deteriorate by the proximity of the window to the gas range. This is due to the shorter distance that external fresh air must travel within the kitchen before it reaches the exhaust fan.

• 설비공학논문집
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• 제12권3호
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• pp.284-291
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• 2000

A basic pulse tube refrigerator has been constructed with extensive instrumentation to study the characteristics of the heat exchanger experimentally under the oscillating pressure and the oscillating flow. This paper describes the sequential experiments with the basic pulse tube refrigerator. The experiments were performed for various cycle frequencies under the square pressure wave forms. First, the heat flux was measured through the cycle at the both cold and warm end heat exchangers without the regenerator. In order to enhance the thermal communication capability of the heat exchanger with the gas at low operating frequencies, a unique design of the triangular shape radial fin concept was applied to the heat exchangers. For the fin heat exchanger, the measured heat flux and the calculated heat flux from the two well-known oscillating heat transfer correlations were compared and discussed. Second, the regenerator was added to the pulse tube to make a basic pulse tube refrigerator configuration. The experiment showed the great impact of the regenerator on the temperature and the heat flux profiles. At the warm-end, the cyclic averaged heat flux had its maximum value at the specific operating frequency. The paper presents the explanation of the surface heat pumping effect as well as the experimental data.

• 설비공학논문집
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• 제16권12호
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• pp.1117-1125
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• 2004

In this study, in order to utilize the waste heat of industrial wastewater in the range of the relatively low temperature of 40～5$0^{\circ}C$ as a heat source, a hybrid heat pump system was considered by computer simulation method. In the simulation, an absorber, desorber and solution heat exchanger were modelled by UA values while a compressor and pump performance were specified by an isentropic efficiency. Simulation results show that the performance of hybrid heat pump can be up to 80% higher than that of conventional R134a heat pump when it makes a process hot water of 9$0^{\circ}C$ while the wastewater is cooled down to 2$0^{\circ}C$. As the absorber pressure increases, the system performance and deserter pressure increase with a favorable effect of a compressor discharge gas temperature drop.

• 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.