• Title/Summary/Keyword: refrigerant flow rates

Search Result 43, Processing Time 0.022 seconds

The Effects of Oil on Refrigerant Flow through Capillary Tubes (냉동기유가 모세관내의 냉매유량에 미치는 영향)

  • 홍기수;황일남;민만기
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.12 no.9
    • /
    • pp.791-801
    • /
    • 2000
  • An experimental study was conducted to analyze the effects of oil on refrigerant flow through adiabatic capillary tubes, and to develop a model for mass flow rates of refrigerant/oil mixture at various capillary tubes and flow conditions. Mass flow rates and the profiles of the pressures and temperatures along the capillary tubes was obtained with the oil concentration of R-22/SUNISO 4GS oil mixture at various test conditions. The flow trends as a function of geometry and flow conditions for pure refrigerant and refrigerant/oil mixture were similar in adiabatic capillary tubes. Mass flow rate of the refrigerant/oil mixture was less than that of pure refrigerant at the same test conditions.

  • PDF

Evaluation of the operating reliability on the concurrent heating-cooling system air conditioner for different refrigerant flow rates with high-head and long-line conditions (동시냉난방 시스템 에어컨의 냉매량 변화에 따른 고낙차 장배관 운전 신뢰성 평가)

  • Lee, Seung-Chan;Kim, Tae-An;Tae, Sang-Jin;Jung, Gyoo-Ha;Moon, Je-Myung;Kim, Youn-Jea
    • Proceedings of the SAREK Conference
    • /
    • 2008.11a
    • /
    • pp.304-309
    • /
    • 2008
  • The heating and cooling performances of system multi-air conditioner for various refrigerant flow rates with high-head and long-line conditions are experimentally investigated. The maximum head and tube length were 110 m and 1000 m, and the two different adjustments of refrigerant flow rates were +20 % and -20 %, respectively. The experimental system was composed of 4 outdoor units with module systems, and 13 indoor units which were joined with the mode change unit by single-tube circuit. Field tests without indoor and outdoor temperature control were performed in a general office building with two different refrigerant flow rates. Especially, the oil level in the compressor was normally maintained at the safety zone. Experimental results were prepared on the p-h diagram.

  • PDF

Analysis of the Gravity Effect on the Distribution of Refrigerant Flow in a Multi-circuit Condenser (다분지 응축기의 냉매유량 분배에 미치는 중력의 영향을 고려한 해석방법)

  • Lee Jangho;Kim Moo Hwan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.16 no.12
    • /
    • pp.1167-1174
    • /
    • 2004
  • The method to consider gravity effect on the performance of a condenser is developed, and a simple condenser having 'nU' type two circuits is analyzed. Each circuit has the same length and inlet air-side operational conditions. The only difference between two circuits is the direction of refrigerant flow, which is exactly opposite each other between the upper 'n' type circuit and the lower 'U' type circuit. It is shown that the gravity makes the distribution of refrigerant flow uneven in the two circuits at lower refrigerant flow rates; heat transfer rate also becomes uneven. Moreover, much of the refrigerant exists as liquid state in the circuit having low refrigerant flow rate, which will make the cycle balance unstable in the refrigeration cycle system like a heat pump.

Computer Simulation on the Performance of Air-Cooled Condenser for an Absorption Heat Pump (흡수식 열펌프용 공냉식 응축기의 성능특성에 관한 시뮬레이션)

  • 박윤철;민만기
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.19 no.8
    • /
    • pp.1999-2011
    • /
    • 1995
  • Computer simulation was conducted to study performance characteristics of air-cooled condenser of a double effect absorption heat pump with variations of saturation pressures and mass flow rates of the refrigerant ; volume flow rates, relative humidities and temperatures of the air The vertically installed condenser had the staggered tube array with continuous plate fins of wavy type. When the saturation pressure of the condenser was decreased from 760 torr to 20 torr, heat transfer rates and condensing rates of refrigerant were decreased. If excess refrigerant flows in the condenser, the pressure and saturation temperature of the condenser were increased which makes the refrigerating capacity of an absorption heat pump reduced.

Numerical analysis on the impeller of chiller compressor using refrigerant R12 (R12 냉매를 이용한 냉동압축기 임펠러 유동해석)

  • Eum, Hark-Jin;Kang, Shin-Hyoung
    • Proceedings of the KSME Conference
    • /
    • 2001.06e
    • /
    • pp.696-701
    • /
    • 2001
  • The performance and the internal flow of the impeller of the centrifugal chiller compressor with refrigerant R12 as working fluid were studied numerically, using CFD code, CFX-Tascflow, which is commercially available. In this numerical study, the thermodynamic and transport properties of the refrigerant gas were generated by the property program of NIST and linked with main program to extend the capability of the code to refrigerant gases. Numerical study was applied to several mass flow rates near the design mass flow rate at constant rotating speed. Overall performance and flow characteristics of the impeller at impeller exit were investigated. The results were physically reasonable and showed good agreement with experimental measurement at the design flow rate.

  • PDF

Flow Characteristics of Refrigerant Mixtures with R32 in a Capillary Tube (R32를 포함한 R22 대체 혼합냉매의 모세관 유동 특성)

  • Chang, S.D.;Ro, S.T.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.8 no.2
    • /
    • pp.177-186
    • /
    • 1996
  • The characteristics of the flow of pure HFC refrigerants(R32, R125, and R134a) and their mixtures through capillary tubes were investigated experimentally. Two capillary tubes with 1.2mm and 1.6mm inner diameter and 1.5m length were adopted as test sections. Mass flow rates and temperatures and pressures were measured for several condensing temperatures and degrees of subcooling at capillary tube inlet. The effects of the condensing temperature, inner diameter of capillary tube, and subcooling on the mass flow rate of refrigerants were discussed, and the mass flow rates of HFC refrigerants were compared with that of R22. The pressure and temperature distributions along the capillary tube compared with that of R22. The pressure and temperature distributions along the capillary tube show that there is a metastable equilibrium state in the flow through the tube. Underpressure for vaporization increases as refrigerant mass flux increases and inlet subcooling decreases. Empirical correlation was suggested to predict underpressure for vaporization of the HFC refrigerants.

  • PDF

Flow and Pressure Drop Characteristics of R22 in Adiabatic Capillary Tubes

  • Kim, Min-Soo;Kim, Sung-Goo;Ro, Sung-Tack
    • Journal of Mechanical Science and Technology
    • /
    • v.15 no.9
    • /
    • pp.1328-1338
    • /
    • 2001
  • The objective of this study is to present flow and pressure drop characteristics of R22 in adiabatic capillary tubes of inner diameters of 1.2 to 2.0mm, and tube lengths of 500 to 2000mm. Distributions of temperature and pressure along capillary tubes and the refrigerant flow rates through the tubes were measured for several condensing temperatures and various degrees of subcooling at the capillary tube inlet. Condensing temperatures of R22 were selected as 40, 45, and 50$^{\circ}C$ at the capillary tube inlet, and the degree of subcooling was adjusted to 1 to 18$^{\circ}C$. Experimental results including mass flow rates and pressure drops of R22 in capillary tubes were provided. A new correlation based on Buckingham II theorem to predict the mass flow rate through the capillary tube was presented considering major parameters which affect the flow and pressure drop characteristcis.

  • PDF

Investigation on the selection of capillary tube for the alternative refrigerant R-407C (대체냉매 R-407C의 모세관 선정에 관한 연구)

  • 김용환;김창년;박영무
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.10 no.1
    • /
    • pp.56-65
    • /
    • 1998
  • In this paper, experimental investigation of capillary tube performance for R-407C is performed. The experimental setup is made of real vapor-compression refrigerating system. In this study, mass flow rate is measured for capillary tubes of various diameter and length as inlet pressure and degree of subcooling are changed. These data are compared with the results of a numerical model. The mass flow rates of the numerical model are less than by 14% compared with the measured mass flow rates. It is found that mass flow rate and length for R-407c are less than those of R-22 under the same condition. Also based on this experimental study and the numerical model, a set of capillary tube selection charts for R-407C is constructed.

  • PDF

Performance Characteristics of Type II LiBr-H2O Absorption Heat Pump in Accordance with the Refrigerant Heat Exchanger Configuration (냉매 열교환기 구성방법에 따른 제 2종 흡수식 히트펌프의 성능 특성 변화에 관한 연구)

  • Lee, Chang Hyun;Yoon, Jun Seong;Kim, In Gwan;Kwon, Oh Kyung;Cha, Dong An;Bae, Kyung Jin;Kim, Min Su;Park, Chan Woo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.29 no.7
    • /
    • pp.373-384
    • /
    • 2017
  • The objective of this study was to determine the effect of refrigerant heat exchanger on the performance of type II absorption heat pump performance using numerical analysis. Two heat exchange installation methods were used: solution to refrigerant and waste hot water to refrigerant. These methods were compared to the standard model of hot water flow without using refrigerant heat exchanger. When waste hot waters were bypassed to refrigerant heat exchanger, COP was not affected. However, steam mass generation rates were increased compared to those of the standard model. When solutions were bypassed to the refrigerant heat exchanger, results were different depending on the place where the solution rejoined. COP and steam mass generation rates were lower compared to those when waste heat water was passed to refrigerant heat exchanger. Thus, it is possible to obtain higher steam mass generation rates by using waste water and installing refrigerant heat exchanger.

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

  • 김창덕;강신형;박일환;이진호
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.16 no.5
    • /
    • pp.397-407
    • /
    • 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.