Effect of capillary tube on the performance of a simple vapour compression refrigeration system
TL;DR: In this article, the effect of capillary tube geometry on the performance of refrigeration systems was studied using both physical models and mathematical modeling concepts, and the parameters stated above can be further optimized in order to enhance the performance.
Abstract: 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. These parameters can be further studied using physical models and mathematical modeling concepts. The parameters stated above can be further optimized in order to enhance the performance of the refrigeration system.
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TL;DR: In this paper, the effect of the configuration and the capillary tube diameter on the overall performance of a simple vapour compression refrigeration system was studied, and the experimental results revealed that the mass flow rate is maximum for the straight configuration and is least for the helical coiled configuration.
Abstract: 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.
9 citations
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.
2 citations
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
Dissertation•
04 Nov 2009
1 citations
01 Jan 2021
TL;DR: In this article, the domestic refrigerator compressor is interconnected with separate indoor unit of air conditioner and one more capillary tube is augmented with the existing refrigeration unit with indoor unit.
Abstract: Human comfort demand is raised day to day due to climate change, global warming and other environmental issues. Conventional air conditioners provide the human comfort; however, other side it consumes high electricity. So, main objective of the study is to reduce the power consumption. In this study, the domestic refrigerator compressor is interconnected with separate indoor unit of air conditioner. In addition, also one more capillary tube is augmented with the existing refrigeration unit with air conditioner indoor unit. An attempt has been made to investigate the performance parameters for both cases with four different coiling cabinet volumes of 44.4, 3.41, 2.25 and 1.5 m3. The results showed that more refrigeration effect is achieved with augmented one capillary tube in second case condition and the temperature and relative humidity have obtained as 23 °C and 50%, respectively. The power consumption compared to same capacity of existing air conditioner is obtained with 1/3rd times of power for small cooling cabinet area.
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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
"Effect of capillary tube on the per..." refers methods in this paper
...Thamir K. Salim (2012) experimentally investigated the performance of the capillary tube expansion device using R134a as the refrigerant in the system....
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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
01 Jan 2008
Abstract: The simulation of refrigeration cycle is important since the experimental approach is too costly and time-consuming. The present simulation focuses on the effect of capillary tube-suction line heat exchangers (CT-SLHX), which are widely used in small vapor compression refrigeration systems. The simulation of steady states is based on fundamental conservation equations of mass and energy. These equations are solved simultaneously through iterative process. The non-adiabatic capillary tube model is based on homogeneous two-phase model. This model is used to understand the refrigerant flow behavior inside the non-adiabatic capillary tubes. The simulation results show that both of the location and length of heat exchange section influence the coefficient of performance (COP). These results can be used in either design calculation of capillary tube length for refrigeration cycle or effect of suction line heat exchanging on refrigeration cycle.
4 citations
"Effect of capillary tube on the per..." refers methods in this paper
...Sanggoon Park et al. (2008) simulated the effects of a non adiabatic capillary tube on refrigeration cycle....
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