An experimental study of the flow of R-407C in an adiabatic helical capillary tube (original) (raw)
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2014
This paper presents experimental comparison of the R134a flow through lateral coiled capillary tubes-suction line heat exchanger (diabatic) and adiabatic coiled capillary tubes in vapor compression refrigeration cycle (VCRC). The experimental results illustrated that mass flux ratio (G c /G s) is main parameter that affects metastable flow through non-adiabatic coiled capillary tube. Therefore, an increase of the mass flux ratio represents a decrease of the heat transfer rate between the capillary tube and suction line. The measured and saturated pressure distribution also proof that metastable flow in the non-adiabatic coiled capillary tube with 1.397 mm inner diameter, 30 mm coil diameter, 4360 mm length, 4 mm inner diameter of suction tube exists, when the heat transfer rate between the coiled capillary tube and the suction line is weak with mass flux ratio more than 343.
2019
A comprehensive review of the literature on the flow of different refrigerants through the capillary tubes of different geometries and different diameter viz. spiral, straight and helical coiled capillary tube, and 1.12mm, 1.4mm, 1.52mm diameter of capillary tube and R134a and mixture of R134a+hydrocarbon with 28:72 by mass refrigerant has been discussed in this paper. In this paper presents in chronological order the numerical and experimental investigations systematically under different condition. Flow aspects like mass flow rate C.O.P, pressure ratio through the capillary tube have been discussed. Furthermore, comparison of R134a and mixture of R134a + hydrocarbon have also been discussed. In this paper, we have found the best diameter for R134a and for the mixture, and we have also discussed the different geometry of the capillary tube. The paper provides key information about the range of input parameters viz. tube diameter, coil pitch and coil diameter, inlet pressure, and co...
The capillary tube used mostly in the refrigerant flow control devices. Hence performance of the capillary tube should be good for smooth refrigerant flow. Many researchers worked in these area by experimentally and analytically. In this present work analyse the flow analysis of the refrigerant inside a capillary tube for adiabatic flow conditions. The proposed model has predict flow characteristics in adiabatic capillary tubes for a given mass flow rate. In the current work R-22 is replaced by Ammonia refrigerant has been used as a working fluid inside the capillary tube and the capillary tube design is changed straight to coiled capillary, which taken from good literature. The analysis is done in ANSYS CFX 16.2 software. It is observed from the results dryness fraction by using the helical capillary tube (Ammonia refrigerant flow) is better than straight and existing helical capillary tube (R22 refrigerant flow). The best suitable helical coiled design is suggested.
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.
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.
2016
Capillary tubes are widely used as refrigerant flow control device in 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 validation o...
NUMERICAL INVESTIGATION OF CAPILLARY TUBE BY REPLACING THE INSIDE REFRIGERANT AND DIAMETER
The capillary tube used in the mostly in the refrigerant flow control devices. Hence performance of the capillary tube is best for good refrigerant flow. The many researchers had been concluding performance using experimentally, theoretically and analysis based. In this present work analyze the flow analysis of the refrigerant inside a 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 work R-22 is replaced by Ammonia refrigerant has been used as a working fluid inside the capillary tube and the capillary tube design is changed straight to coiled capillary, which taken from good literature. The analysis is done in ANSYS CFX 16.2 software. It is observed from the results dryness fraction by using the helical capillary tube (Ammonia refrigerant flow) is better than straight and existing helical capillary tube (R22 refrigerant flow). The best suitable helical coiled design is suggested.
A Model for Helical Capillary Tubes for Refrigeration Systems
2006
This paper presents a flow model that has been developed to design and study the performance of helical capillary tubes and to mathematically simulate a situation closer to that prevailing in practice. Homogeneous flow of twophase fluid is assumed through the adiabatic capillary tube. The model includes the second law restrictions. The effect variation of different parameters like condenser and evaporator pressures, refrigerant flow rate, degree of subcooling, tube diameter, internal roughness of the tube, pitch and the diameter of the helix on the length of the capillary tube are included in the model. Theoretically predicted lengths of helical capillary tube for R-134a are compared with the length of the capillary tube needed under similar experimental conditions and majority of predictions are found to be within 10% of the experimental value.
The study of the expansion device in simple vapor compression refrigeration system is necessary in order to understand the parameters which can enhance the overall performance of system. It is essential to study the effect of capillary tube geometry on the performance of refrigeration systems. The literature review focuses on the effect that geometrical parameters like capillary tube length, bore diameter, coil pitch, number of twist and twisted angle have on the pressure drop, coefficient of performance (COP) and mass flow rate of the system. The parameters stated above can be further optimized in order to enhance the performance of the refrigeration system. The present work is focused on the influence of tube diameter, tube length, coil pitch, and inlet condition on mass flow rate of refrigerant through helical coil capillary tube and also on investigation about the Coefficient of Performance (COP) of the system due to coiling effect of capillary tube. The use of helical capillary tube reduces the space for the refrigeration system which is the need for more compact refrigeration system in the current trend.