Analytical Investigation of R134a Flowing Through Adiabatic Helically Coiled Capillary Tubes
15 Feb 2017-International Advanced Research Journal in Science, Engineering and Technology-Vol. 4, Iss: 2, pp 139-144
TL;DR: In this article, the effects of the relevant parameters on the flow characteristic of R134a and R-22 flowing through adiabatic helical capillary tubes were experimentally studied.
Abstract: Capillary tubes are used as expansion device in low capacity refrigeration machines like domestic refrigerators and window type air conditioners. The advantages of the capillary tube over other expansion devices are simple, inexpensive and cause compressor to start at low torque as the pressure across the capillary tube equalize during the off-cycle. The flow characteristics of refrigerants through capillary tubes have been studied extensively in past six decades, both experimentally and analytically, most of these studies mainly focused on straight capillary tubes. In this thesis, the effects of the relevant parameters on the flow characteristic of R134a and R-22 flowing through adiabatic helical capillary tubes were experimentally studied. The capillary tubes' diameter, coil diameter, and parameters relating to flow conditions such as inlet pressures and degree of sub cooling were the major parameters investigated. In this thesis, the CFD analysis is to determine the heat transfer rate, pressure drop, velocity, mass flow rate and heat transfer coefficient for the fluids R134A and R-22 with different tube and coil diameters. Thermal analysis is to determine the temperature distribution and heat flux for copper and aluminum as tube materials.3D modeling is done pro-engineer and analysis is done in ANSYS software.
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28 Mar 2021
TL;DR: In this paper, the effect of capillary tube on the performance of VCR system is discussed, and the results of straight and helical type of Capillary tubes are studied.
Abstract: Vapor Compression refrigeration system is most commonly available system in day to day life from home to malls in India. It is necessary to improve the performance of system. The study is mainly focus on the improvement of performance. Out of different parameter, the literature review covers the effect of capillary tube on the performance of system. It covers the experimental and numerical study on effect of capillary tube. The results of straight and helical type of capillary tubes are studied. The study also covers the CFD analysis for the different length and diameters of capillary tubes and find out the optimize size.
2 citations
Cites methods from "Analytical Investigation of R134a F..."
...Buddha Chouhan et al [4] has used capillary tubes as expansion device in low capacity refrigeration machines like domestic refrigerators and window type air conditioners....
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...Buddha Chouhan et al [4] has used capillary tubes as expansion device in low capacity refrigeration machines like domestic refrigerators and window type air conditioners....
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Dissertation•
05 Nov 2009
2 citations
References
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01 Jan 2010
TL;DR: In this paper, the authors presented the development process of refrigerator test rig and performance analysis of a domestic refrigerator, which was developed from refrigerator model NRB33TA National brand and the main objective in this study was to obtain performance of the refrigeration system in term of Refrigeration Capacity, Compressor work and Coefficient of Performance (COP) by determining three important parameters during in operating mode which are temperature, pressure and refrigerant flowrate.
Abstract: Refrigerator is one of the home appliance utilizing mechanical vapour compression cycle in it process. Performance of the system becomes main issue and many researches are still ongoing to evaluate and improve efficiency of the system. Therefore, this paper presents the development process of refrigerator test rig and performance analysis of a domestic refrigerator. The experiment platform which called test rig was developed from refrigerator model NRB33TA National brand. The main objective in this study was to obtain performance of the refrigeration system in term of Refrigeration Capacity, Compressor work and Coefficient of Performance (COP) by determining three important parameters during in operating mode which are temperature, pressure and refrigerant flowrate. In the test rig, all temperature probes were connected to thermocouple scanner to measure temperature at particular points on the refrigeration system. Pressure gauges were used to measure pressure and a magnetic flowmeter was used to measure refrigerant flowrate. In order to avoid effects of a changing the measured data, the environmental of testing was controlled according to Association of Home Appliance Manufacturers (AHAM) standard. There are three sets of experiment data were collected in order to evaluate the refrigerator performance. Each data was collected for a cycle of operation for 2 hours. The result shows that the average COP of the refrigeration system using the refrigerator test rig was about 2.7.
19 citations
01 Jan 2008
TL;DR: In this paper, the authors examined the effects of pitches of both helical and serpentine coiled capillary tubes on the performance of a vapor compression refrigeration system and found that both pitch and height affects the system performance.
Abstract: The effects of various geometries of capillary tubes has been investigated by many researchers. Their studies were based on the coil diameters and lengths alone, with no particular attention placed on the effect of coil pitch. At present no information is available about the effects of serpentine coiled capillary tubes on refrigerator performance. This study examined the effects of pitches of both helical and serpentine coiled capillary tubes on the performance of a vapor compression refrigeration system. Several capillary tubes of equal lengths (2.03 m) and varying pitches, coiled diameters, and serpentine heights were used. Both inlet and outlet pressure and temperature of the test section (capillary tube) were measured and used to estimate the coefficient of performance (COP) of the system. The results show that, in the case of helical coiled geometries the pitch has no significant effect on the system performance but the coil diameter as already predicted by many researchers. In the case of serpentine geometries both pitch and height affects the system performance. Performance increases with both increase in the pitch and the height. Correlations were proposed to describe relationships between straight and coiled capillary tube and between helical coiled and serpentine coiled capillary tubes. The coefficient of correlations are: 0.9841 for mass flow rates of helical and serpentine with straight tubes; 0.9864 for corresponding COPs and 0.9996 for mass flow rates of serpentine and helical coiled tube.
13 citations
Journal Article•
TL;DR: In this article, the behavior of a simple vapour compression refrigeration system was studied while its working under transient conditions occurred during cooling of a fixed mass of brine from initial room temperature to sub-zero refrigeration temperature.
Abstract: The behavior of performance parameters of a simple vapour compression refrigeration system were studied while its working under transient conditions occurred during cooling of a fixed mass of brine from initial room temperature to sub-zero refrigeration temperature. The effects of different lengths of capillary tube over these characteristics have also been investigated. It was concluded that with the constantly falling temperature over evaporator, refilling of it with more and more liquid refrigerant causes multifold increase in heat transfer coefficient which helps in maintaining refrigeration rate at falling temperature. Larger capillary tube decreases the tendency of refilling of evaporator but offers less ‘evaporator temperature’ effective in lower range of refrigeration temperature. Shorter capillary tube ensures higher COP initially but which deteriorates at a faster rate in lower temperature range. Capillary tube length must be optimized for maximum overall average COP of the system for the complete specified cooling job.
9 citations
TL;DR: In this article, a real vapor compression refrigeration system was used to investigate the performance of the capillary tube performance for (R134a) and found that the best coil number in refrigeration cycle at the lowest mass flow rate (31 Kg/hr) and at high mass flow ratio (23 Kg /hr) is (coil number = 4), this will give the highest performance, cooling capacity and lowest theoretical compression power.
Abstract: The capillary tube performance for (R134a) is experimentally investigated. The experimental setup is a real vapor compression refrigeration system. All properties of the refrigeration system are measured for various mass flow rate from (13 – 23 kg/hr) and capillary tube coil number (0-4) with fixed length (150 cm) and capillary diameter (2.5mm). The results showed that the theoretical compression power increases by (65.8 %) as the condenser temperature increases by (2.71%), also the theoretical compression power decreases by (10.3 %) as the capillary tube coil number increases. The study shows also that the cooling capacity increases by (65.3%) as the evaporator temperature increases by (8.4 %), and the cooling capacity increases by (1.6%)as the capillary tube coil number increases in the range (0-4). The coefficient of performance decreases by (43.4 %), as the mass flow rate increases by (76.9%), also the coefficient of performance increases by (13.51 %) as the capillary tube coil number increases in the range (0-4). Through this study, it was found that the best coil number in refrigeration cycle at the lowest mass flow rate (31 Kg/hr) and at high mass flow rate (23 Kg/hr) is (coil number = 4), this will give the highest performance, cooling capacity and lowest theoretical compression power.
9 citations
01 Jan 2006
TL;DR: In this article, a flow model was developed to design and study the performance of helical capillary tubes and to mathematically simulate a situation closer to that prevailing in practice, including second law restrictions.
Abstract: 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.
6 citations
"Analytical Investigation of R134a F..." refers background or methods in this paper
...AN EXPERIMENTAL STUDY OF THE EFFECT OF CAPILLARY TUBE DIAMETER AND CONFIGURATION ON THE PERFORMANCE OF A SIMPLE VAPOUR COMPRESSION REFRIGERATION SYSTEM 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 [1] [2] of the system....
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...A simple vapour compression refrigeration system consists of mainly five components namely compressor, condenser, expansion device, evaporator and a filter/drier[1]....
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