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        검색결과 48

        1.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the present study, a calorimeter was used to experimentally investigate the heating capacity and COP changes according to the pipe length of a variable capacity A/C system with long pipes. Cooling capacity, COP, and compressor discharge temperature were obtained by changing pipe lengths and loading duties at fixed indoor and outdoor temperatures. And the operation status and cycle change process of the A/C system were investigated using some experimental data and P-h diagrams. As the pipe length changes, the heat transfer within the cycle and the operating load of the compressor change, so the heating capacity and COP of the system change. At the same loading duty, as the pipe length increases, the heating capacity and COP decrease. As the loading duty increased, the heating capacity increased almost linearly, but the COP decreased. Since the long pipe experimental value for the compressor discharge temperature has a temperature deviation of up to 1 7℃(50m, L/D : 10/10) from the correlation equation, the optimal correlation equation must be derived through additional research.
        4,000원
        2.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the present study, a calorimeter was used to experimentally investigate the cooling capacity and COP changes according to the pipe length of a variable capacity A/C system with long pipes. Cooling capacity, COP, and compressor discharge temperature were obtained by changing pipe length and loading duty. And the operation status and cycle change process of the A/C system were investigated using some experimental data and P-h diagrams. In long pipes, the pressure drop increases and the operating load on the compressor increases. Additionally, at the same loading duty, cooling capacity and COP decrease and the compressor discharge temperature increases. As loading duty increases, cooling capacity and compressor power consumption increase. Since the temperature deviation between the experimental value and the correlation equation for the discharge temperature of the long-pipe compressor shows a maximum of 10.5℃(50m, L/D : 20/0), the existing correlation equation needs to be modified.
        4,000원
        3.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the heating performance of a variable capacity A/C system was experimentally studied. A psychrometric calorimeter was used to obtain performance data of the A/C system using PWM(pluse width modulation) method and compare it with the compressor discharge temperature correlation equation. Heating capacity, COP, and compressor discharge temperature were obtained by changing indoor and outdoor temperatures, refrigerant amount, and loading duty. The following results were obtained by selecting 5 types of refrigerant amount, 3 types of outdoor temperature (fixed indoor temperature), and 2 types of loading duty. As the outdoor temperature increases, heating capacity and COP increase. Heating capacity was affected by both outdoor temperature and loading duty. However, COP was more influenced by outdoor temperature. The effect of increasing the amount of refrigerant on the performance of the A/C system was not significant. Additionally, the temperature deviation between the existing compressor discharge temperature correlation equation and the heating experiment data was about 5.1℃ at the maximum loading duty.
        4,000원
        4.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the cooling performance of a variable capacity A/C system was experimentally studied. A psychrometric calorimeter was used to obtain performance data of the A/C system using the pulse width modulation method and compare it with the compressor discharge temperature correlation equation. Cooling capacity, COP, and compressor discharge temperature were obtained by changing indoor and outdoor temperatures, refrigerant amount, and loading duty. The following results were obtained by selecting 5 types of refrigerant amount, 3 types of outdoor temperature (fixed indoor temperature), and 2 types of loading duty. As the outdoor temperature increased, cooling capacity and COP according to outdoor conditions decreased. And the higher the loading duty, the greater the cooling capacity, but the COP was minimal. The change in cooling capacity and COP due to the increase in refrigerant amount was not significant. Additionally, the change in compressor discharge temperature is more influenced by the outside temperature than by the loading duty.
        4,000원
        5.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the present study, the experimental study was conducted using a multi-calorie meter, to investigate the cooling performance and cycle operation changes of the multi-heat pump (3 indoor units) for the low outside temperature in summer. The test temperature condition was the low cooling temperature, and the normal performance and dynamic behavior of 3 rooms, 2 rooms, and 1 room were measured to understand the operating characteristics of seven 7 indoor unit combinations. As a result of the experiment, the cooling capacity and COP of the multi-heat pump at low cooling temperature were about 10% and 6% higher than those of the cooling standard temperature. In addition, the dynamic behavior of the indoor units of 3 and 2 rooms was observed differently due to the load difference according to the indoor unit combinations and the non-uniformity of the refrigerant amount. And, when starting the heat pump, the compressor had a maximum peak value and stabilized by repeating the decrease and increase for each indoor unit combination.
        4,000원
        6.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the present study, to investigate the cooling characteristics of the multi-heat pump with 3 indoor units, 7 indoor unit combinations and 3 setting temperatures are selected to study the cooling characteristics during steady-state operation. The cooling capacity, power consumption, COP, compressor high and low pressure of the heat pump are tested under the cooling standard temperature conditions using an air enthalpy multi-calorimeter. The experimental results show that, except for an operation with an indoor unit capacity of 30% or less, the cooling capacity, power consumption, and compressor operation frequency increase as the capacity of the indoor unit increases and the setting temperature of the indoor unit decreases. COP increases or decreases according to the compressor frequency, and is the best at 50-80% capacity of the indoor unit. As the compressor frequency increases, the compressor outlet pressure increases by about 30%.
        4,200원
        7.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to experimentally investigate the operation characteristics of the multi-heat pump with 3 indoor units, the dynamic characteristics of the cooling cycle is studied using the psychrometric multi-calorimeter. The compressor of the heat pump is the scroll inverter type, and since 3 indoor units operate cooling at the same time, it is operated at 100% full load. In particular, 3 types of indoor unit temperatures (20, 24, 26°C) are selected to understand the operation process of the multi-heat pump by the setting temperature. From this experiment, the compressor controls the EEV opening for each indoor unit while varying the frequency according to the initial start, transient, and steady operation. In addition, as the setting temperature increases in the steady range, the frequency of the compressor and the average opening degree of the EEV decrease.
        4,000원
        8.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the present study, it is conducted to understand the heating performance and compressor operation characteristics according to 7 indoor unit combinations and 3 setting temperatures of the inverter multi-heat pump under heating standard temperature conditions. Heating capacity, COP and compressor frequency are investigated using the multi-calorimeter. The indoor unit combinations are simultaneous operation(A+B+C), partial operation(A+C, A+B, B+C) and independent operation(A, B, C), and the setting temperature is 20, 21, and 30°C. Since the increase in the setting temperature increases the compress frequency, the heating capacity increases, but COP decreases due to the increase in power consumption. The frequency increases as the indoor unit combination capacity increases, and decreases as the setting temperature decreases in the steady state.
        4,000원
        9.
        2022.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The performance characteristics and usefulness of the duct-type gas removal system to which the catalytic combustion method was applied were investigated by experiment. Benzene, toluene, ethylbenzene, and xylene were selected for performance tests on gas detection and removal of the catalytic combustion system. Accelerated experiments were performed to evaluate the gas sensing performance, the adsorption performance of activated carbon, and the basic performance and durability of the catalytic combustion system. The amount of gas adsorption in the adsorption stage was changed according to the type of activated carbon, adsorption temperature and time. The adsorption amount increased with increasing temperature and particle size. BTEX gas removal rate was about 96%, and the performance of the module was maintained for more than 4,000 hours.
        4,000원
        10.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, a heat exchange system using cooling dehumidification and mixing process was proposed as an experimental study for a white smoke reduction heat exchanger system under winter condition. The white smoke reduction heat exchange system is divided into an EA part, SA part, W part and mixing zone. For the operating conditions, three types (Cases 1, 2, and 3) were selected depending on whether EA fan, SA fan, and A-W heat exchanger were operated. In addition, in order to visualize the white smoke exhausted from the mixing zone, it was photographed using CCTV. In order to investigate the performance of the white smoke reduction heat exchange system, the temperature reduction rate and absolute humidity reduction rate of EA and the heat recovery rate of W were calculated. The temperature change of EA and SA according to operating conditions was most effective in Case 3, and the temperature and absolute humidity at the outlet of the mixing zone were greatly reduced. From the results of the white smoke visualization, it was confirmed that the white smoke generation mechanism was different depending on the operating conditions, and the amount of white smoke generation was greatly reduced.
        4,000원
        11.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to study the drying performance of the dryer, the performance characteristics of the heat pump dryer applied a PF heat exchanger is applied were experimentally investigated. The capacity, COP, drain and SMER of the dryer were measured by the refrigerant charge and EEV opening. Heat pump dryers are refrigerant-air systems. For the dryer performance test, an air enthalpy calorimeter was used. From the experimental results, the heat exchanger performances according to the change in the refrigerant charge and EEV opening were the maximum at 0.5kg refrigerant and 30% EEV opening, respectively. In addition, SMER suggested a satisfactory level of drying performance. This shows that the refrigeration cycle of the dryer must be operated at an appropriate refrigerant amount and EEV opening degree to secure optimal drying performance. On the other hand, the time to reach the target setting temperature of the dryer was increased by about 2.5 times depending on with/without the sample.
        4,000원
        12.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Driving safety of a semi-trailer is greatly reduced when driving in a section with a narrow turning radius, so a dynamic study of driving and road conditions is required. In this study, the driving stability of the semi-trailer was investigated using the RecurDyn program in consideration of the velocity and weight of the semi-trailer in the entrance curve section of the highway, and the turning angle and radius of the curved road. In order to select the model and analysis conditions according to the road type, the sloping curved road was modeled by selecting the curvature, entry length, height difference, and entrance angle of the curved section. From the analysis results, the higher the semi-trailer's entrance velocity, the heavier the weight, the narrower the entrance angle of the curved road, and the smaller the curvature, the greater the semi-trailer's maximum running angular speed which had an effect on driving stability.
        4,000원
        13.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the present paper, the natural fiber materials that can be replaced to reduce the weight of the vehicle are analyzed by bubble charts of - and - , and the possibility of alternative application of materials is investigated. For this purpose, the driving energy and fuel efficiency of the vehicle using the data of K model analyzed. In addition, the effect of vehicle weight on fuel efficiency was analyzed through the dynamic analysis approach of the vehicle. From the research results, the following results were obtained. Most of natural fibers have lower density and equal tensile strength and strain than metal materials. Therefore, the application rate of natural fiber materials should be increased in consideration of the application purpose and material characteristics of the vehicle. The major variables that greatly influence driving energy and fuel efficiency were fuel efficiency improvement of about 10% in order of speed, rolling resistance and mass. In addition, when steel is lightened by 10%, fuel efficiency improvement of up to maximum 4.5% is shown in the order of CFRP, Al, Ti.
        4,000원
        14.
        2020.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the flat glass and adsorption pad were modeled using SolidWorks Simulation, to understand the deformation characteristics of the vertical flat glass by the adsorption pressure during vertical transport of LCD. The horizontal and vertical displacements and equivalent stresses of the flat glass were investigated by the structural analysis. From the displacement and stress visualization according to the adsorption pressure, the higher the adsorption pressure, the larger the glass surface protruded. The horizontal deformation of flat glass increased with increasing thickness and the vertical deformation increased with decreasing thickness. In addition, the maximum equivalent stress applied to the flat glass increased significantly as the adsorption pressure increased and the thickness decreased. As a result of the structural analysis, the thinner the thickness of the plate glass, the greater the effect on the adsorption pressure. Especially, the effect of the adsorption pressure was clearly observed at the thickness of 0.5mm.
        4,000원
        15.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the uniformity of the horizontal velocity and the temperature of each zone were investigated by computerized analysis method to divide the drying room into three multi - rooms to ensure the uniformity of flow inside the forced convection hot air dryer. The internal structure of the drying room of the dryer was modeled using Solidworks. In order to control the flow of hot air circulating in the drying chamber, the possibility of controlling the horizontal flow inside the drying room was verified by using a perforated plate, a guide vane, and a vertical plate. From the results of the flow visualization in the drying room, it was understood that the internal flows of the dryer models 1, 2 and 3 change from ununiform flow to uniform flow. From the analysis of velocity and temperature fluctuation, the results of the analysis of the dryer model 3 satisfied the design conditions.
        4,000원
        16.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, a white smoke reduction simple prediction model of white smoke reduction heat exchange system was developed by using EES. In order to verify the reliability of the EES model, it was compared with the computational results. The developed EES predictive model was used to calculate the temperature and absolute humidity of the mixed SA and EA according to the change of cooling water capacity, flow rate ratio of SA/EA, and SA inlet temperature. The difference between final temperature and absolute humidity at the outlet of the mixer calculated by computational analysis and EES was within 1.4% and 3.6%. As the cooling water capacity and the inlet flow rate ratio increased, and as the inlet air temperature decreased, the temperature and absolute humidity of the mixer decreased. The most influential factor in the white smoke reduction effect among the design variables of the white smoke reduction heat exchange system was the flow rate ratio of SA/EA.
        4,000원
        17.
        2019.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the structural stability of an align unit was studied to investigate the deformation and vibration characteristics of the upper and lower modules of the align unit during LCD panel transfer. The align unit consists of upper module and lower module. SolidWorks Simulation was used to analyze the structure, fatigue, and modes, to understand the deformation and vibration of the stiffness of the align unit. Because of the upper eccentric structure of the align unit, the main strain was large at the contact of the upper and lower modules and at the bottom of the support, and more pronounced at it’s front. The stress was large in the front support of the upper and lower modules, and the displacement was observed in the front of the upper module. The minimum life cycle that indicates the structural integrity of the align unit has exceeded its usable number. Also, the increase in natural frequency of the align unit gradually slowed down, as the vibration mode increased.
        4,000원
        18.
        2019.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the change of cooling water temperature (72, 85, 95 ℃) and engine speed (1,800, 2,000, 2,200, 2,400rpm) were experimentally investigated to confirm the operation performance characteristics of auxiliary engine for refrigeration unit. The experimental setup consisted of fuel consumption meter, power meter, and heat transfer unit. The operation performances such as BSFC, exhaust temperature, power generation, and engine efficiency of the auxiliary engine showed similar characteristics in the present experimental range, according to the change of cooling water temperatures and rpms. As the torque increased, the BSFC decreased significantly and the exhaust temperature increased. The power generation increased linearly and the efficiency was insignificant at more than 40 Nm torque.
        4,000원
        19.
        2019.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the temperature, the absolute humidity, and the turbulent flow characteristics of exhaust air and supply air in the mixer were studied while changing the shape of the mixer of the white smoke reducing heat exchange system. Using Solidworks, the mixer of the white smoke reduction heat exchange system was created by 3-D model. Also, the mixed flow of supply air and exhaust air inside the mixer under the uniform inlet conditions was computed, using the solidworks flow simulation. Two types of improvement models were selected by using a perforated plate and a guide vane as a turbulent mixing flow control method of the mixer. The mean temperature and mean absolute humidity of the mixture were greatly decreased according to the internal shapes of Case 1, 2, and 3. The temperature difference between the inlet and outlet of the mixer Case 3 was 26℃. The exit temperature and absolute humidity reduction rates of Case 3 were 26.2% and 48.1%, respectively, compared with Case 1.
        4,000원
        20.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the performances of the refrigeration unit for the box under actual operating conditions were examined by using the constant temperature and humidity chamber (air enthalpy method). For this purpose, the degree of superheat, pressure, and temperature were measured while changing the EEV opening, the compressor speed, the outdoor temperature, and the load in the refrigeration cycle of the refrigeration unit. The highest cooling performance was found at EEV 33%. However, EEV 35% with low compression ratio and degree of superheat was the most reliable in terms of reliability. Considering the compressor speed and cooling performance, the refrigeration unit was in an optimal condition at the compressor speed 3,040RPM. The results of this study will be provided as basic data for the optimal design of refrigeration units for box.
        4,000원
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