• Title/Summary/Keyword: Air-side performance

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Modeling of the Air-side Particulate Fouling in Finned-Tube Heat Exchangers of Air Conditioners using Accelerated Particle-Loading System (파울링 가속장치를 이용한 공기조화기용 열교환기의 공기측 파울링 특성에 대한 예측 모델링)

  • Ahn Young-Chull;Lee Jae-Keun
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.3
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    • pp.262-267
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    • 2005
  • The air-side particulate fouling in the heat exchangers of HVAC applications degrades the performance of cooling capacity, pressure drop across a heat exchanger, and indoor air quality. Indoor and outdoor air contaminants foul heat exchangers. The purpose of this study is to investigate and to model the air-side particulate fouling characteristics of the heat exchangers using accelerated particle loading system. The main variables of the modeling equation are face velocity and dust concentration. The modeling equation shows good agreements with the experimental results at the face velocity of 0.5, 1.0, 1.5 m/s and the dust concentration of 1.28 and $3.84\;g/m^3$. It will be very useful to predict fouling characteristics such as variations of pressure drop and heat transfer capacity in finned-tube heat exchangers of air conditioners.

Air Flow Analysis on Driving Truck with or without Side Pairing (사이드 페어링 장착 유무에 따른 구동 트럭에서의 공기 유동 해석)

  • Choi, Kyekwang;Cho, Jaeung
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.5
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    • pp.14-20
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    • 2020
  • In this study, the overall states of the airflow when a truck with or without side pairing is driven at a maximum speed of 90 km/h, regulated by domestic law, were investigated through computational fluid dynamics numerical analysis. All the tested models showed that the airflow went under the truck body; specifically, the air did not flow along the underside to the rear of the truck but through the sides of its underside. The drag with the drag coefficient at model 3 was clearly higher than those for the other two models. The results of this study could help to improve the truck performance by reducing its resistance against the air flown from it in driving itself.

Development of a Drain-Type Electronic Dehumidifier Using Thermoelectric Element (열전소자를 이용한 배수형 전자제습기 개발)

  • Kang, Deok-Hong;Kim, Seong-Hwan;Kim, Ki-Hong
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.3524-3528
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    • 2007
  • In this study, the Peltier effect was applied to eliminate moistures in the air enclosed by a cabinet. We have developed the new electronic dehumidifier which has a new function of automatically evaporating the condensed water inner cabinet into the outside air. To obtain this function, the processes of dehumidification is that it condensed the moistures on the cold side heat sink and drained it into the hot side heat sink by the both gravitational and capillary forces and the droplets on the hot side heat sink surface was evaporated into the air outside the cabinet by the heat conducted through the hot side heat sink surface and the forced heat convection through the fan for cooling hot side heat sink. Compared to existing electronic dehumidifiers, this manufactured one showed a good performance that the electric power consumption for the same dehumidifying quantity was reduced by 50% compared with that of existing ones.

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Evaluation of Air-side Friction Characteristics on Design Conditions of Slit Fin and Tube Heat Exchanger (슬릿휜-관 열교환기의 설계조건에서 공기측 압력강하 산출)

  • Cho, Sung-Chul;Kim, Chang-Duk;Kim, Chang-Eob;Kwon, Jeong-Tae;Lim, Hyo-Jae
    • Journal of Energy Engineering
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    • v.16 no.3
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    • pp.149-154
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    • 2007
  • An experimental study on the air-side pressure drop of slit fin-tube heat exchanger has been carried out. The data reduction methodology for air-side pressure drop in the literature is not based on a consistent approach. This paper focuses on method of data reduction to obtain the air-side performance of fin-tube heat exchanger using R22 and recommends standard procedures for dry and wet surface pressure drop estimation in fin-tube heat exchanger. A comparison was made between the predictions of previously proposed empirical correlations and experimental data for the air-side pressure drop on design conditions of condenser and evaporator. Results are pre-sented as plots of friction f-factor against Reynolds number based on the fin collar outside diameter and compared with previous studies. The data covers a range of refrigerant mass fluxes of $150{\sim}250\;kg/m^2s$ with air flows at velocity ranges from 0.38 m/s to 1.6 m/s.

An Experimental Study on the Optimal Operation Condition of an Air-Cooler using Thermoelectric Modules (열전모듈을 이용한 냉방기의 최적 운전조건에 관한 실험적 연구)

  • Hwang, Jun;Kang, Byung-Ha
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.1
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    • pp.66-72
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    • 2006
  • This article presents the optimal operation of an air conditioner using thermoelectric modules. A prototype of air conditioner using four thermoelectric modules has been designed and built. The system performance with evaporative cooling for hot side of the module are studied in detail for several operating parameters, such as input power to the thermoelectric module, fans and pump. It is found that the optimal input voltage to the thermoelectric module and pump is selected for the best system performance based on the cooling capacity and the COP at a given operating condition. It is also found that both the cooling capacity and COP of a system is increased with an increase in the input power to fans. The cooling performance could be improved when the ambient temperature is increased and the relative humidity is decreased since the evaporative cooling at the hot side has been increased.

A Study on Performance of Thermoelectric Air-Cooling System in Parallel Flow (평행유동에서 공랭식 열전모듈 냉각시스템의 성능에 관한 연구)

  • Karng, Sarng-Woo;Shin, Jae-Hoon;Han, Hun-Sik;Kim, Seo-Young
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.23 no.6
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    • pp.421-429
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    • 2011
  • Experimental and theoretical studies on cooling performance of two-channel thermoelectric air-cooling system in parallel flow are conducted. The effects of operating temperature to physical properties of thermoelectric module (TEM) are experimentally examined and used in the analysis of an air-cooling system considering thermal network and energy balance. The theoretical predicted temperature variation and cooling capacity are in good agreement with measured data, thereby validating analytic model. The heat absorbed rate increases with increasing the voltage input and decreasing thermal resistance of the system. The power consumption of TEM is linearly proportional to mean temperature differences due to variations of the physical properties on operation temperature of TEM. Furthermore thermal resistance of hot side has greater effects on cooling performance than that of cold side.

An Experimental Study on Performance Characteristic of 30RT Closed-Type Hybrid Cooling Tower using Bare Tube (베어관을 이용한 30RT급 하이브리드 밀폐형 냉각탑의 성능특성에 관한 실험적 연구)

  • Jun, Chul-Ho;Lee, Ho-Saeng;Moon, Choon-Geun;Kim, Jae-Dol;Yoon, Jung-In
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2005.06a
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    • pp.1096-1101
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    • 2005
  • In this study, the experiment of thermal performance about closed-type hybrid cooling tower was conducted. A closed type cooling tower is a device similar to a general cooling tower, but with cooling tower replaced by a heat exchanger. The test section for this experiment has the process that the cooling water flows from top part of heat exchanger to bottom side in the inner side of tube, and spray water flows gravitational direction in the outer side of it. Air contacts of tube outer side are counterflow. The heat transfer pipe used in this experiment is a bare type tube having an outside diameter of 15.88mm. In this experiment, heat performances of the cooling tower are calculated such as overall heat transfer coefficient of between the process fluid and air, cooing capacity and pressure drop.

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A Study on Optimum Design Condition for 'HEAT PUMP' System in Korea (한국에 있어서의 히이트 펌프계의 최적 설계 조건에 관한 연구)

  • Choe, Yeong-Bae
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.10 no.4
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    • pp.304-315
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    • 1981
  • This paper presents, the result of the study for the fluctuant temperature of the out-side air adopting the heat pump system in seoul, Taejean, Taegu, Busan and Jejeu among principle cities in korea for the purpose of checking the heating capacity, Heat pump capacity (outlet capacity), Coefficient of performance and running cost in comparison with the supporting the energy for the boiler's operation. According to the supply temperature changes of the out door coil by the out side air-return air mixing ratio, the Coefficient of performance is increased from 3. 1 to 5.0. Particularly, in Taegu, it is necessary to adopt the heat pump system against the supplement heat supply on the full outside air intake in January of the heating period, and it was recognized that the running cost is cheaper than that of the Boiler use. At the same time, if it is able to get $25\%$ of return air of the inside in the Seoul, it could be saved its costs when we use the supplementary boiler. And I think it is necessary to the development.

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Performance Characteristics of a Regenerative Heat Exchanger Depending on Its Porous Structure (스털링 엔진용 재생 열교환기의 다공체 구조에 따른 성능 특성)

  • Shin, Myung-Chul;Ahn, Joon;Kang, Byung-Ha
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.5
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    • pp.415-421
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    • 2012
  • Stirling engine is an external combustion engine, whose efficiency approaches that of Carnot engine with the help of a regenerator. The regenerator is a heat exchanger composed of porous medium, whose performance is dependent on the pore structure. Three types of pore structures are considered in the present study. They are wire screen, random wire and composite structure, i.e. a combination of wire screens with different hydraulic diameters. The porosity more highly affects the performance of a regenerator compared to the hydraulic diameter. The random wire can yield high effectiveness even at a high porosity. The composite mesh gives better performance when the hydraulic diameter decreases in the direction from hot side to cold side.

Design and Analysis of A Rectangular Type Core for A Contactless Power Transmission system (비접촉 진력전송 시스템을 위한 'ㅁㅓ'형 코어 설계 및 분석)

  • Jin, Kang-Hwan;Kim, Ji-Min;Kim, Soo-Hong;Kim, Eun-Soo;Kim, Yoon-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.1
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    • pp.52-57
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    • 2008
  • In the transformer that is used for the contactless power transmission system, the primary and secondary sides are separated structurally unlike general transformers. When the contactless transformer is built, it forms relatively bigger air gap than the general transformer. Thus it is difficult to transfer energy from the primary side input to the secondary side output with high power efficiently because of low coupling coefficient. This paper proposes a contactless transformer using the rectangular type core that maintains high coupling coefficient even when it has relatively large air gap. The performance characteristics of the proposed transformer are compared with the transformer using general EE core to the air gap variation. The proposed contactless system using rectangular type core and dc-dc full bridge converter, and the system using EE core type and dc-dc full bridge converter are respectively implemented and their performance characteristics are verified by the simulation and experiment.