Numerical investigation of refrigerant flow through adiabatic capillary tube (original) (raw)
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International Journal of Current Engineering and Technology, 2016
In the present study, phase change of refrigerant flow through capillary tube under adiabatic conditions has been studied based on computational fluid dynamics technique. Eulerian multiphase flow Homogeneous equilibrium model along with thermal phase change based on mass transfer mechanism was used for simulation of refrigerant flow through adiabatic straight capillary tube. The effect of various design parameter such condensation pressure, capillary tube length and capillary tube diameter on the flashing inception point has been discussed numerically. The numerical model based on finite volume method using turbulence model gives the behavior of refrigerant properties such as field of pressure, temperature, dryness fraction, void fraction and velocity along the distance of capillary tube which helps in the understanding of beginning of vaporization phenomenon. The present numerical model has been validated with the others models and a good agreement are obtained which can be lead to depend up on ANSYS CFX 16.1 in design and optimization of capillary tube of refrigeration industry.
Improved refrigerant characteristics flow predictions in adiabatic capillary tube
Research Journal of Applied Sciences, Engineering and Technology, 2012
This study presents improved refrigerant characteristics flow predictions using homogenous flow model in adiabatic capillary tube, used in small vapor compression refrigeration system. The model is based on fundamental equations of mass, momentum and energy. In order to improve the flow predictions, the inception of vaporization in the capillary tube is determined by evaluating initial vapor quality using enthalpy equation of refrigerant at saturation point and the inlet entrance effect of the capillary tube is also accounted for. Comparing this model with experimental data from open literature showed a reasonable agreement. Further comparison of this new model with earlier model of Bansal showed that the present model could be use to improve the performance predictions of refrigerant flow in adiabatic capillary tube.
IJERT-Simulation of Flow Characteristics of Refrigerant inside Adiabatic Straight Capillary Tube
International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/simulation-of-flow-characteristics-of-refrigerant-inside-adiabatic-straight-capillary-tube https://www.ijert.org/research/simulation-of-flow-characteristics-of-refrigerant-inside-adiabatic-straight-capillary-tube-IJERTV2IS90720.pdf In the present investigation, an attempt is made to develop mathematical model to determine the flow characteristics of refrigerant inside a straight capillary tube for adiabatic flow conditions. The proposed model can predict the length of the adiabatic straight capillary tube for a given mass flow rate. In the present study R-12 has been used as a working fluid inside the straight capillary tube of diameter 1.17 mm and 1.41 mm and used the same model to study the flow characteristics of refrigerant in ANSYS CFX software. Finally the results of mathematical model are valuated with ANSYS CFX and the results are found to be in fair agreement.
Numerical analysis of adiabatic flow of refrigerant through a spiral capillary tube
International Journal of Thermal Sciences, 2009
In the present work, a homogenous model including the metastable liquid region has been developed for the adiabatic flow of refrigerant through the spiral capillary tube. In order to develop the model, both liquid region and two phase region have been discretized into infinitesimal segments to take into account the effect of varying radius of curvature of spiral tube on the friction factor. The effect of the pitch of spiral on the mass flow rate of refrigerant and capillary tube length has been investigated. A comparison of flow characteristics of refrigerant R22 and its alternatives, i.e., R407C and R410A has been made at different operating conditions at the inlet of the capillary tube and it has been found that the flow characteristics of R22 and R407C are almost similar for a given condenser pressure and degree of subcooling at the inlet of capillary tube.
IJERT-CFD Flow Analysis of a Refrigerant inside Adiabatic Capillary Tube
International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/cfd-flow-analysis-of-a-refrigerant-inside-adiabatic-capillary-tube https://www.ijert.org/research/cfd-flow-analysis-of-a-refrigerant-inside-adiabatic-capillary-tube-IJERTV2IS90289.pdf Capillary tubes are widely used as a refrigerant flow control device in small refrigeration systems. Since the flow behaviour inside the capillary tube is complex, many physical models are necessary to predict the characteristics of the refrigerant flow in a capillary tube. The refrigerant leaves the compressor at high pressure and temperature and enters the condenser. After leaving the condenser the refrigerant is at medium temperature and high pressure and then it enters the Capillary tube. In the Capillary tubes the pressure and the temperature of the refrigerant is reduced drastically and suddenly. Thus us it is the throttling valve where the temperature of the refrigerant is reduced and it is then able to produce the cooling effect in the evaporator of the refrigerator or the cooling coil of the air conditioner. In the present investigation, an attempt is made to analyze the flow Analysis of the refrigerant inside a straight capillary tube and coiled capillary tube for adiabatic flow conditions. The proposed model can predict flow characteristics in adiabatic capillary tubes for a given mass flow rate. In the present study R-22 has been used as a working fluid inside the straight capillary tube and coiled capillary tube of diameter 1.27 mm and used the same model to study the flow characteristics of refrigerant in ANSYS CFX software. It is observed from the results dryness fraction by using the helical capillary tube is better than straight capillary tube. The best suitable helical coiled design is suggested.
CFD Parametric Investigation for Two Phase Flow of Refrigerant 134 a In an Adiabatic Capillary tube
2016
Capillary tubes are widely used as refrigerant flow control device in a small refrigeration systems. Since the flow behavior inside a capillary tube is complex, several physical models are necessary to predict the characteristics of refrigerant flow in the capillary tube. A refrigerant leaves the compressor at high pressure & temperature and enters the condenser. After leaving the condenser the refrigerant is at medium temperature & high pressure and then it enters the Capillary tube. In a Capillary tubes the pressure and the temperature of a refrigerant is reduced drastically and suddenly. Thus us it is a throttling valve where the temperature of the refrigerant is reduced and it is then able to produce the cooling effect in evaporator of the refrigerator or cooling coil of the air conditioner. In the present investigation, an attempt is made to analyze the two phase flow of the refrigerant 134a inside a helical capillary tube for adiabatic flow conditions. First of all a validatio...
Experimental investigation of R600a refrigerant flow inside adiabatic capillary tube
Sigma Journal of Engineering and Natural Sciences, 2016
Capillary tubes are often used as an expansion component in the refrigeration systems of household refrigerators. During the flow of the refrigerant inside the capillary tube, due to pressure loss of the refrigerant, the refrigerant starts boiling and towards the end of the capillary tube, different types of twophase regimes occur. Therefore; the refrigerant flow inside the capillary tube is a complex phenomenon and there are many experimental and numerical studies analyzing this refrigerant flow. However; in literature there are hardly any experimental studies analyzing refrigerant flow in small scale refrigeration systems using isobutane (R600a) as the refrigerant. In this study, the two-phase flow regimes of the R600a refrigerant inside a vertical adiabatic capillary tube with 0.80 mm inner diameter, under different condensation pressures subcooling degrees and capillary tube lengths, are recorded via high-speed camera; and the effects of different parameters on refrigerant mass flow are analyzed. The boundary conditions for the condensation pressure, subcooling degree and capillary tube length are determined in accordance with a small scale refrigeration system.
2017
After study of many literatures gives the knowledge of flow of characteristics of refrigerant through capillary tube as well as to know about the working fluids for refrigeration system. In present study, the many household refrigerators used a different type of refrigerants as per as their characteristic, the R600a refrigerant have been discussed. In study of many literatures it is concluded that the capillary tube used in refrigerator for refrigerant flow has been suitable for helix coiled tube. Also it is concluded that R600a refrigeratnt is low GWP and low flammable refrigerant, so application of this of refrigerant is suitable for replacing R12, R22 and R134a.
Numerical Study on Refrigerant Mixtures Flow in Capillary Tubes
1998
This paper presents a numerical study on the performance of capillary tubes with R-22 and some alternatives considered for R-22 replacement, namely R-407C, R-410A and R-134a. It is compared the mass flow rate as function of inlet conditions (condensing temperature, subcooling degree or inlet quality) for a given geometry. Numerical results show that, taking R-22 as the reference, R-407C mass flow rates are slightly higher (about 5%), R-410A presents about 30% higher mass flow rates and R-134a presents nearly 30% lower mass flow rates. These results are connected with the different saturation pressure curves for each fluid NOMENCLATURE A Area X quality c sound speed y molar fraction Cc contraction coefficient z position d diameter a void fraction f Darci friction factor creJ relative rouglmess G mass flux a area ratio h specific enthalpy subscripts he convection heat transfer coefficient cd condenser, condensation k liquid conductivity ct capillary tube m mass flow rate ev evaporator...
REVIEW OF REFRIGERANT FLOW IN ADIABATIC CAPILLARY TUBE
After study of many literatures gives the knowledge of flow of characteristics of refrigerant through capillary tube as well as to know about the working fluids for refrigeration system. In present study, the many household refrigerators used a different type of refrigerants as per as their characteristic, the R600a refrigerant have been discussed. In study of many literatures it is concluded that the capillary tube used in refrigerator for refrigerant flow has been suitable for helix coiled tube. Also it is concluded that R600a refrigeratnt is low GWP and low flammable refrigerant, so application of this of refrigerant is suitable for replacing R12, R22 and R134a.