• 제목/요약/키워드: Air side pressure drop

검색결과 103건 처리시간 0.027초

동일한 유입온도조건에서 R410A와 R22 적용 응축기의 특성비교 (Comparison of Condenser Characteristics using R410A and R22 under the Same Inlet Temperature Condition)

  • 김창덕;이진호
    • 설비공학논문집
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    • 제15권12호
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    • pp.1049-1059
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    • 2003
  • R410A is considered as an alternative refrigerant to R22 for air conditioners. An experimental investigation was made to study the characteristics of the heat transfer and pressure drop for R410A flowing in a fin-and-tube heat exchanger used for commercial air-conditioning units. Experiments were carried out under the conditions of inlet refrigerant temperature of 6$0^{\circ}C$ and refrigerant mass flux varying from 150 to 250 kg/$m^2$s for refrigerant side. The inlet air has dry bulb temperature of 35$^{\circ}C$, relative humidity of 40% and air velocity varying from 0.68 to 1.6 m/s. Experiments show that air velocity decreased by 16% is needed for R410A than that of R22 for subcooling temperature of 5$^{\circ}C$, which resulted in air-side pressure drop decrease of 15% for R410A as compared to R22. As a consequence, in order to provide the same design condition of a condenser, the fan requires lower electric-power consumption with R410A than that with R22.

동일한 유입온도조건에서 R407C와 R22 적용 응축기의 특성비교 (Comparison of Condenser Characteristics Using R407C and R22 on the Same Inlet Temperature Condition)

  • 김창덕;전창덕;이진호
    • 설비공학논문집
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    • 제15권7호
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    • pp.595-603
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    • 2003
  • R407C is considered as an alternative refrigerant to R22 for air conditioners. An experimental investigation was made to study the characteristics of the condensation heat transfer and pressure drop for R407C flowing in a fin-and-tube heat exchanger used for commercial air-conditioning units. Experiments were carried out under the conditions of inlet refrigerant temperature of 6$0^{\circ}C$ and refrigerant mass flux varying from 150 to 250 kg/$m^2$s for refrigerant side. The inlet air has dry bulb temperature of 35$^{\circ}C$ , relative humidity of 50% and air velocity varying from 0.8 to 1.6 m/s. Experiments show that air velocity increased by 25% is needed for R407C than that of R22 for subcooling temperature of 5$^{\circ}C$, which resulted in air-side pressure drop increase of 28.8% for R407C as compared to R22. As a consequence, in order to provide the same design condition of a condenser, the fan requires higher electric-power consumption with R407C than that with R22.

공기조화기용 열교환기의 공기측 파울링 가속 특성 분석 (An experimental study of the air-side particulate fouling in finned-tube heat exchangers of air conditioners through accelerated tests)

  • 안영철;조재민;이재근;이현욱;안승표;윤덕현;강태욱;옥주호
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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    • pp.1857-1862
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    • 2003
  • 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 the fouling characteristics trough accelerated tests. The fouling characteristics are analyzed as functions of a dust concentration (1.28 and 3.84 $g/m^3$), a face velocity (0.5, 1.0, and 1.5 m/s), and a surface condition. The cooling capacity in the slitted finned-tube heat exchangers at the face velocity of 1 m/s decreases about 2% and the pressure drop increases up to 57%. The rate of build-up of fouling is observed to be 3 times slower for this three-fold reduction of dust concentration whilst still approaching the same asymptotic level.

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Plate and Shell 열교환기의 압력강하 특성에 관한 연구 (A study on the pressure drop characteristics of plate and shell heat exchangers)

  • 서무교;김영수
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 춘계학술대회논문집B
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    • pp.25-30
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    • 2000
  • Plate and shell heat exchanger(P&SHE) has been applied to the refrigeration and air conditioning systems as evaporators or condensers fur their high efficiency and compactness. The purpose of this study is to analyze the characteristics of pressure drop in plate and shell heat exchanger. An experiment for single phase (low pressure drop in plate and shell heat exchanger was performed. Also numerical work was conducted using the FLUENT code for $ {\kappa}-{\varepsilon}$ model. The dependence of friction factor on geometrical Parameters was numerically investigated. The study examines the internal flow and the pressure distribution in the channel of plate and shell heat exchanger. The results of CFD analysis compared with experimental data, and the difference of frictor factor in plate side and shell side are 10% and 12%, respectively. Therefore, the CFD analysis model is effectively predict the performance of plate and shell heat exchanger.

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응축압력 변화에 따른 R407C의 응축특성에 관한 연구 (An Experimental Study on Condensation Characteristics at Various Condensation Pressure of R407C)

  • 전창덕;장경근;김창덕;이진호
    • 설비공학논문집
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    • 제15권3호
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    • pp.230-238
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    • 2003
  • R407C is considered as alternative refrigerant of R22 for air conditioners. Experimental investigation is made to study the condensation heat transfer characteristics of slit fin-tube heat exchanger using alternative refrigerant, R407C. Experiments are carried out at condensation pressure of 2110 kPa and 1943 kPa with the degree of superheat of 1$0^{\circ}C$ and mass flux varying from 150 to 250 kg/$m^2$s for refrigerant side. The inlet air condition is dry bulb temperature of 35$^{\circ}C$, relative humidity of 50% and air velocity varying from 0.8 to 1.6 m/s. Experiments show that pressure drop gets smaller at a higher condensation pressure especially when condensation pressure is raised from 1943 to 2110 kPa. Heat transfer rate gets smaller at a lower condensation pressure in the range of experimental condition.

Corrugate 휜-관 현열 열교환기의 구조에 따른 공기측 열전달 및 압력손실 특성 (Characteristic of air-side sensible heat transfer and pressure drop on the corrugate fin tube heat exchangers)

  • 류준일;전창덕;이진호;남임우
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2007년도 동계학술발표대회 논문집
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    • pp.216-221
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    • 2007
  • An experiment was carried out to investigate the effect of a coolant circuit arrangement on the heat transfer and air pressure drop of a fin-tube sensible heat exchanger with the corrugated fin surface. The air inlet temperature was set to $23^{\circ}C$,the relative humidity to 50% and the air inlet flow rate to 20, 22, $25m^3/min$, respectively. while the coolant temperature was set to $7^{\circ}C$, and the coolant mass flow rate to 10, 16, 22kg/min, respectively. Experiment showed that the exchanger having a diameter of 12.7mm with parallel circuit does better performance in sensible heat transfer and air pressure drop than those three of diameter of 12.7mm with a series circuit and that with diameter of 15.88mm with a parallel circuit.

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증발기의 압력강하에 대한 상대습도의 영향 (Effects of Relative Humidity on the Evaporator Pressure Drop)

  • 김창덕;강신형;박일환;이진호
    • 설비공학논문집
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    • 제16권5호
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    • pp.397-407
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    • 2004
  • It is well known that some key parameters, such as evaporating temperature, refrigerant mass flow rate, face velocity and inlet air temperature, have significant influence on the evaporator performance. However performance studies related to a humid environment have been very scarce. It is demonstrated that the refrigerant mass flow rate, heat flux, water condensing rate and air outlet temperature of the evaporator significantly increase with air inlet relative humidity. As the air inlet relative humidity increases, the latent and total heat transfer rates increase, but the sensible heat transfer rate decreases. The purpose of this study is to provide experimental data on the effect of air inlet relative humidity on the air and refrigerant side pressure drop characteristics for a slit fin-tube heat exchanger. Experiments were carried out under the conditions of inlet refrigerant saturation temperature of 7 $^{\circ}C$ and mass flux varied from 150 to 250 kg/$m^2$s. The condition of air was dry bulb temperature of 27$^{\circ}C$, air Velocity Varied from 0.38 to 1.6 m/s. Experiments Showed that air Velocity decreased 8.7% on 50% of relative humidity 40% of that at degree of superheat of 5$^{\circ}C$, which resulted that pressure drop of air and refrigerant was decreased 20.8 and 8.3% for 50% of relative humidity as compared to 40%, respectively.

단상유동 조건에서 용접형 판형 열교환기의 열전달 및 압력강하 특성연구 (Heat Transfer and Pressure Drop Characteristics of Brazed Plate Heat Exchangers with Single-Phase Flow)

  • 김만배;박창용
    • 설비공학논문집
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    • 제26권11호
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    • pp.522-528
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    • 2014
  • This experimental study measured and analyzed the heat transfer and pressure drop performance of brazed plate heat exchangers. Heat exchangers with different plate numbers of 10, 20, 30, and 40 were used for measurement, and their plate pattern was identical. The experiment was performed with distilled water, by changing the hot-side flow rate, with the cold-side flow rate fixed. The experimental results were compared with the calculated values by correlations based on gasketed plate heat exchangers, and showed that the heat transfer performance and pressure drop of brazed plated heat exchangers were higher than those of gasketed plate heat exchangers. From the variation of the friction factor, it could be inferred that in the flow channels of brazed plate heat exchangers, turbulent flow occurred at Reynolds numbers higher than 500. A new correlation to predict the Nusselt number was developed, and its absolute average deviation was 2.62%, compared with the values from the experimental data.

냉동기 펌프다운 운전성능에 관한 연구 (A Study on Pump Down Operation Performance of Refrigerator)

  • 김철수;정한식;정효민
    • 설비공학논문집
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    • 제18권12호
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    • pp.964-970
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    • 2006
  • Vapor compression refrigerators have much critical variables such as the controls of temperature and pressure switches, control durations and operating hours of electronic valves. This study compares and analyzes the data which is obtained from system controlling of the evaporation temperatures which are generally used in automatic pump down operating systems. Through this study, the automatic evaporation control operation system will be more ideal for the system to keep the proper temperature distribution depending on the purpose of evaporation side. The automatic pump down control operation is more appropriate for the system to aim at the effective use of evaporation side without using the temperature difference. And this test will be proved that the changes at the low pressure side didn't have significant impacts on the high pressure side.

전단동축형 분사기의 유량계수에 대한 형상학적 변수들의 영향 (Effect of Geometrical Parameters on Discharge Coefficients of a Shear Coaxial Injector)

  • 안종현;이근석;안규복
    • 한국분무공학회지
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    • 제25권3호
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    • pp.95-102
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    • 2020
  • Six shear coaxial injectors for a 3 tonf-class liquid rocket engine using oxygen and methane as propellants were designed and manufactured by considering geometric design parameters such as a recess length and a taper angle. Cold-flow tests on the injectors were performed using water and air as simulants. By changing the water mass flow rate and air mass flow rate, the injection pressure drop under single-injection and bi-injection was measured. The discharge coefficients through the injector oxidizer-side and fuel-side were calculated and the discharge coefficient ratio between bi-injection and single-injection was obtained. Under single-injection, the recess served to reduce the injection pressure drop on the injector fuel-side. For the injectors without recess, the discharge coefficients under bi-injection were almost the same as those under single-injection. However, for the injectors with recess, the taper angle and bi-injection had a significant effect on the discharge coefficient.