Effect of capillary tube on the performance of a simple vapour compression refrigeration system (original) (raw)
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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.
The study of the expansion device in the simple vapour compression refrigeration system is necessary in order to understand the parameters which can enhance the overall performance of the system. The experimental study was done on the capillary tubes of 31 gauge, 36 gauge and 40 gauge and each test section was studied with three distinct configurations i.e. helical coiled, straight coiled and serpentine coiled configuration. The effect of the configuration and the capillary tube diameter on the overall performance of the system was studied. The findings of the experimental study revealed that the mass flow rate is maximum for the straight configuration and is least for the helical coiled configuration. The refrigeration effect was found to be maximum for the helical coiled configuration and was found to be least for straight coiled configuration. The compressor work was found to reduce as the load was increased on the system. Decreasing the capillary tube diameter increased the mass flow rate in the system and decreased the refrigeration effect produced.
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...
IJRASET, 2021
The capillary tube is commonly employed in refrigerant flow control systems. As a result, the capillary tube's performance is optimal for good refrigerant flow. Many scholars concluded performance utilising experimental, theoretical, and analysis-based methods. This paper examines the flow analysis of a refrigerant within a capillary tube under adiabatic flow circumstances. For a given mass flow rate, the suggested model can predict flow characteristics in adiabatic capillary tubes. In the current work, R-134a refrigerant has been replaced by R600a refrigerant as a working fluid inside the capillary tube, and the capillary tube design has been modified by altering length and diameter, which were obtained from reputable literature. The analysis is carried out using the ANSYS CFX 16.2 software. The results show that utilising a small diameter and a long length (R-600a refrigerant flow) is superior to the present helical capillary tube. The most appropriate helical coiled design with a diameter of 0.8 mm and a length of 3 m is proposed.
The Effect of Capillary Tube Length & Diameter on Compressor Performance of Refrigeration System
African Journal of Advanced Pure and Applied Sciences (AJAPAS) , 2024
As the name suggests, the compressor is a device that compresses and raises the pressure of the refrigerant vapor coming from the evaporator, resulting in a saturation level that is higher than that of the chilled medium. As a result, the compressor needs to be powered by the actuator or main engine. The compressor can be referred to as a heat pump since it transfers heat from a low-temperature medium (the evaporator) to a high-temperature medium (the condenser). To determine how the capillary tube's width and length affected the compressor's performance in the refrigeration system, a basic refrigeration system was put together and used in this study. Three distinct lengths of capillary tubes were used, which are ((3m, 2m, 1m)) and two different diameters, which are (2.0mm, 2.2mm). Among the results obtained, the best performance coefficient and equivalent to the size of the compressor used were achieved when using the length ((1m)) and diameter ((2.0mm)) for the capillary tube, where the performance coefficient was ((6.8)).
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.
2010
In this work, the performance of alternative refrigerants in adiabatic capillary tube was investigated experimentally in a vapour compression refrigeration system. The mass flow rate was determined at a series of condensing temperatures, degree of sub-cooling and at various lengths of capillary tube. The average mass flow rate of R152a and R134a were 1.2 % lower and 1.9 % higher than that of R12 respectively, at the same operating conditions. The coefficient of performance (COP) obtained using R134a and R152a refrigerants were very close to that of R12 with only 2.6% and 1.3 % reduction respectively, while the COPs obtained using R23, R32 and R143a were significantly very low. The performance obtained in a refrigeration system differs among individual selected alternative refrigerants. The differences are larger for R143a, R32 and R23, and the deviation from the performance of R12 is in that order, while the differences are smaller or negligible for R134a and R152a. The best overall performance is obtained using R152a.
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.
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.
Heat and Mass Transfer, 2011
Small vapor compression refrigeration systems incorporate a non-adiabatic capillary tube called a capillary tube-suction line heat exchanger (SLHX) in order to improve performance. The thermodynamic properties of the refrigerant in the capillary tube and suction pipe are influenced by associated phenomena. This study compares various relevant models. Based on the comparison recommended correlations were selected and the simulation results show that the friction factor model has the most dominant.