• Title/Summary/Keyword: Air-pump

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기액 이상류시의 스크류식 원심펌프의 압력분포 (Pressure Distributions of a Screw-type Centrifugal Pump Operating in Air-Water Two-Phase Flow)

  • 김유택;최민선;이영호
    • 한국유체기계학회 논문집
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    • 제4권3호
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    • pp.39-45
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    • 2001
  • It is reported recently that the pump head deterioration near the best efficiency point, from single-phase flow to the choke due to air entrainment became less in a screw-type centrifugal pump than in a general centrifugal pump. Moreover, at a narrow tip clearance, the pump head became partially higher in two-phase flow than that in single-phase flow. However, the internal pressure fluctuations on this pump due to air entrainment have not been studied yet. For that reason, we have examined the influences of void fraction, flow coefficient and impeller tip clearance on pressure fluctuations in the casing. The void fraction became larger, the influence of tip clearance on pressure distribution became less.

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에어컨 배수펌프 설치 실태 및 개선방안 분석 - 창원시를 중심으로 (Analysis on Installation Conditions Survey and Improvement of Drain Pump in Air-Conditioner : Focusing on Changwon City)

  • 김성삼
    • 조명전기설비학회논문지
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    • 제26권8호
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    • pp.102-106
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    • 2012
  • This paper was carried out to survey fire hazard and improvement at the drain pump in air-conditioners. Based on the results of analysis, the proposal of electrical accidents prevention and a construction improvement are as follows. A power connection of the drain pump has two types, an electrical outlet type and direct connection type at control board of air-conditioner. The electrical outlet types need a bulletin sign or education as malfunction of the drain pump include an additional accidents, current leakage and overflowing with water on the floor from breaker trip by exterior cause and breaker off by mistake of worker. On the other hand, the direct connection types prevent a power interruption as exterior cause, but it has some trouble, cut of ground cable and without protection device. Usually it doesn't work by electrician when air-conditioner and the drain pump power work. Therefore an education or countermeasures are recommended for not electrician. Generally malfunction of the drain pump causes accumulated materials into the tank. Even though the accumulated materials lead to an overheating and burning as failure of detector occur an idling, periodic inspection of the air-conditioner filter and the drain pump tank prevent the trouble.

공기열원 히트펌프의 난방 성능특성에 관한 실험적 연구 (Experimental Study on Heating Performance Characteristics of Air Source Heat Pump with Air to Water Type)

  • 이권재;권영철;전종균;박삼진;권정태;허철
    • 설비공학논문집
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    • 제23권6호
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    • pp.400-405
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    • 2011
  • This paper presents the heating performance characteristics of the air source heat pump with air to water type. The heating capacity, COP, P-h diagram were measured at various operating conditions, air-side temperatures, relative humidities, and inlet/outlet water temperature under the standard heating condition of KS B 6275. The experimental data for the heat pump were measured using the air-enthalpy calorimeter and the constant temperature water bath. As the air-side temperature increases, the heating capacity and COP increase. The effect of the air-side relative humidities on the heat pump performance is insignificant. The heat pump performance on inlet and outlet water temperatures and air-side temperatures(-7, -11, $-15^{\circ}C$) were studied. Heating capacity and COP increased about 27~39% with the air-side temperature increasing. Enthalpy between the front and the rear of condenser decreased about 6% by increasing of the inlet water temperature. These results can be utilized in the design of the air source heat pump system with air to water type.

하천수 열원 열펌프 시스템의 성능 특성 및 경제성 평가 (Performance Characteristics and Economic Assessment of a River Water: Source Heat Pump System)

  • 박차식;정태훈;박홍희;김용찬
    • 설비공학논문집
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    • 제21권11호
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    • pp.621-628
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    • 2009
  • The objectives of this study are to analyze the performance of a river water-source heat pump and to carry out economic assessment for the heat pump. The COP of the river water-source heat pump was 3-21% higher than that of the air-source heat pump because river water provides stable operating temperature compared with air temperature throughout the year. The economic analysis was carried out by comparing the initial and operating cost of the river water-source heat pump with those of the conventional air-source heat pump. The ratio of the life cycle operating cost to the life cycle cost increased with the increase of building capacity. The payback period was found to be less than 3.5 years when the capacity of the river water-source heat pump was larger than 10 RT.

기포펌프의 형상 및 작동 조건에 따른 전산유동해석 (Computational Flow Analysis with Geometric and Operating Conditions of Air Lift Pump)

  • 강건한;김성초;최종욱
    • 한국가시화정보학회지
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    • 제18권2호
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    • pp.18-27
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    • 2020
  • Air lift pump operated by buoyancy is mainly used for the continuous circulation and the purification of fluids. In this study, the computational flow analysis has been performed with the geometric and operating conditions of the air lift pump. The numerical data from the analysis have been verified by comparing with the previous experimental data. The following results are obtained which advance the efficiency of the air lift pump. As the submergence length of pipe increases and the pipe length over the water surface decreases, the non-dimensional mass flow ratio increases in both cases. When the position of the air injection hole is within the pipe, the circulation range of the surrounding fluid becomes widened with the distance between the air injection hole and the pipe inlet relatively becoming narrower. It is more efficient both when the air injection velocity is at 10 m/s and at 15 m/s, and when the diameter of the pipe with holes is doubled near the water surface. It is expected that these results can be provided as fundamental data for operating the air lift pump.

저온측과 고온측 냉매간 열교환이 열펌프의 성능특성에 미치는 영향 (Effect of the Heat Exchange between Low and High Temperature Refrigerant on the Heat Pump Performance)

  • 이건중;송현갑
    • 한국농업기계학회:학술대회논문집
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    • 한국농업기계학회 1999년도 동계 학술대회 논문집
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    • pp.211-218
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    • 1999
  • The ambient air is commonly used as low-temperature heat sources for heat pump operation. However, the coefficient of performance (COP) of the air -water heat pump is decreased with the ambient air temperature drop. In this study to solve this problem , the AVACTHE(Automatic Variable Area Capillary Type Heat Exchanger) with 3 levels of heat exchange area(0, 1495.4, 1794.5$\textrm{cm}^2$) was installed in the refrigerant circuit of the heat pump. The AVACTHE effect on the performance of heat pump was tested with the ambient air temperature variation. The high level COP of the heat pump could be achieved by the AVACTHE installation when below -5$^{\circ}C$ of the ambient air temperature.

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공기흡입에 의한 스크류식 원심펌프의 양수불능 특성에 관한 연구 (A Study on the Break-down Characteristics of a Screw-type Centrifugal Pump due to Air Entrainment)

  • 김유택
    • 한국유체기계학회 논문집
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    • 제6권3호
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    • pp.58-63
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    • 2003
  • The performance of turbo pump drops rapidly and it gets into break-down when the void fraction reaches above the threshold value because the impeller flow passage is choked up with air bubbles. Phenomenological understanding of break-down and pumping recovery mechanisms under air-water two-phase flow conditions are therefore important for pump designers and essential assignment for researchers. In this paper, we investigated the characteristics of break-down and pumping recovery due to entrained air occurring inside a screw-type centrifugal pump which has a wide flow passage mainly through the findings of suction and discharge pressures, rotational speed, flow rate measurements and visualization.

물-공기 히트펌프 시스템의 부분부하 난방운전 특성 (Performance Characteristics of Water-to-Air Heat Pump under Partial Load Heating Operation)

  • 조용;이남영;김용열;김대근;정응태
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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    • pp.170.1-170.1
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    • 2010
  • Performance of water-to-air heat pump using raw water has been analyzed under part load heating operation in March, 2010. The water source heat pump of 30 RT was installed for 24 hours cooling and heating ventilation, and the gravity inflow water from Daechung dam is used as the heat source. The daily averaged water and air temperatures are $5.7^{\circ}C$ and $9.9^{\circ}C$ respectively, and the heat pump is operated under part load condition for 7.5 hours in 24 hours. The daily averaged heat pump COP calculated with heat transferred from the brine water is 2.49 and the monthly averaged COP is 2.25 in March. Based on the database of the California Energy Commission, the monthly averaged COPs of air source heat pumps installed in U.S.A. are 1.97 in March and 2.03 in April. Therefore it is confirmed again that the performance of the heat pump using raw water is better than that of air source heat pumps.

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전열교환기가 설치된 기류전환형 히트펌프의 동계운전성능에 관한 실험적 연구 (An Experimental Study on the Operating Performance of an Air Shift type Heat Pump with Heat Exchanger)

  • 장영근
    • 설비공학논문집
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    • 제22권8호
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    • pp.567-572
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    • 2010
  • Air shift type heat pump is combined heat recovery ventilator and refrigerator, and it is installed an air shifter changing air flow. And so it is an perfect AHU(Air Handling Unit) capable to cooling, heating, ventilation and heat recovery. Therefore, an experimental study has been carried out to investigate the operating performance in winter for this system. An experimental data are room temperature, inlet/outlet temperature of condenser, evaporator and heat exchanger. They have been measured as the variation of outdoor temperature. The results, in case of rising above freezing, the air shift type heat pump system is operated normally, and the heating COP is 3.0~4.2 by varying outdoor temperature from $-3^{\circ}C$ to $15^{\circ}C$.

이중관 열교환기를 사용한 물 대 공기 열펌프 시스템의 설계와 성능해석 (Design and performance analysis of water-to-air heat pump system using double-tube heat exchanger)

  • 한도영;박관준
    • 설비공학논문집
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    • 제9권4호
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    • pp.462-471
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    • 1997
  • The water-to-air heat pump system requires relatively lower energy consumption and less installation space. The heat exchangers used for this system are the finned-tube type for the indoor unit and the double-tube type for the outdoor unit. Mathematical models for this system are developed and programmed in computer. Experimental data from various conditions are obtained and compared with calculated values from the computer simulation program. Differences of cooling capacity and COP are 1.25% and 0.47%, and those of heating capacity and COP are 0.51% and 0.13%, respectively. Simulation results are in good agreement with test results. Therefore, the developed program is effectively used for the design and the performance prediction of water-to-air heat pump system.

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