The Effect of the Capillary Tube Coil Number on the Refrigeration System Performance
01 Jun 2012-Tikrit Journal of Engineering Science (Tikrit University جامعة تكريت)-Vol. 19, Iss: 2, pp 18-29
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.
Citations
More filters
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
Cites result from "The Effect of the Capillary Tube Co..."
...The diameter of the capillary tube used in the refrigeration appliances varies from 0.5mm to 2.3mm. the effect of the capillary tube has been investigated by many researchers in the past and encouraging results were obtained....
[...]
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.
5 citations
Cites methods from "The Effect of the Capillary Tube Co..."
...Thamir K. Salim (2012) experimentally investigated the performance of the capillary tube expansion device using R134a as the refrigerant in the system....
[...]
01 Jan 2016
TL;DR: In this paper, a domestic refrigerator was experimentally studied by simultaneously varying the refrigerant charge (mr) and the capillary tube length (L), and the potential of replacing R12 by R600a was also investigated.
Abstract: In this work, the thermodynamic performance of a domestic refrigerator was experimentally studied by simultaneously varying the refrigerant charge (mr) and the capillary tube length (L). The potential of replacing R12 by R600a was also investigated. The test rig for the experiment was a vapor compression refrigerator designed to work with R12. The enthalpy of the refrigerants R600a and R12 for each data set for the experimental conditions were obtained by using REFPROP software (version 9.0). The results show that the design temperature of -120C (according to ISO - 8187 standard) and pull – down time of 135 minutes are achieved by using 60g of R600a with L= 1.2m and 1.5m. For R12, the design temperature is achieved at pull – down time of 165 minutes with mr = 40g and L = 0.9m. The appropriate combination of L and mr for R600a to be used as a drop-in refrigerant for R12 is found to be 1.5m and 60g on the basis of power consumption per day, pull-down time and COP, whereas by considering the cooling capacity, it is 0.9 m and 60g. The cooling capacity of R600a was about 9.18% higher than that of R12, the power consumed by R600a was about 24 % lower than that of R12 and the COP of R600a was about 6.3% higher than that of R12. In conclusion, the proposed R600a seems to be an appropriate long-term candidate to replace R-12 in the existing refrigerator in terms of power consumption, cooling capacity and COP.
5 citations
Cites methods from "The Effect of the Capillary Tube Co..."
...For instance, Wei et al. (2000) compared coiled and straight capillary tubes by using R22, to study the effect of coiling on the performance of VCRS....
[...]
TL;DR: In this article, a comparative experimental study on the performance of a domestic refrigerator using R600A and LPG with varying refrigerant charge (wr) and capillary tube length (L) was carried out.
Abstract: A comparative experimental study on the performance of a domestic refrigerator using R600A and LPG with a varying refrigerant charge (wr) and capillary tube length (L) was carried out. The enthalpy of the refrigerants R600A and LPG for each data set for the experimental conditions were obtained by using REFPROP soft ware (version 9.0). The results show that the design temperature and pull-down time set by ISO for a small refrigerator are achieved earlier using refrigerant charge 60 g of LPG with a 1.5 m capillary tube length. The highest COP (4.8) was obtained using 60-g charge of LPG with L of 1.5-m. The average COP obtained using LPG was 1.14% higher than that of R600A. Based on the result of electric power consumption, R600A off ered lowest power consumption. The compressor consumed 20% less power compared to LPG in the system. The system performed best with LPG in terms of COP and cooling capacity, while in terms of power consumption R600A performed best.
4 citations
Cites background from "The Effect of the Capillary Tube Co..."
...…cooling capacity, kW r refrigerant Wc compressor work, kW suc suction Volume 18, Issue 4, 2017 dimensions and geometry on the performance of a vapor compression refrigeration system (Fiorelli and Silvares, 2004; Guobing and Yufeng, 2006; Salim, 2012; Matani and Agrawal, 2013; Pathak et al., 2014)....
[...]
...Volume 18, Issue 4, 2017 dimensions and geometry on the performance of a vapor compression refrigeration system (Fiorelli and Silvares, 2004; Guobing and Yufeng, 2006; Salim, 2012; Matani and Agrawal, 2013; Pathak et al., 2014)....
[...]
Journal Article•
TL;DR: In this paper, an attempt is made to develop mathematical model to determine the flow characteristics of refrigerant inside a straight capillary tube for adiabatic flow conditions and the results of mathematical model are valuated with ANSYS CFX.
Abstract: 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. Key word: adiabatic straight capillary tube, refrigerant R12, ICEM, CFD AND ANSYS CFX.
3 citations
References
More filters
TL;DR: A comprehensive review of the literature on the flow of various refrigerants through the capillary tubes of different geometries viz. straight and coiled and flow configurations viz. adiabatic and diabatic, has been discussed in this paper.
Abstract: A comprehensive review of the literature on the flow of various refrigerants through the capillary tubes of different geometries viz. straight and coiled and flow configurations viz. adiabatic and diabatic, has been discussed in this paper. The paper presents in chronological order the experimental and numerical investigations systematically under different categories. Flow aspects like effect of coiling and effect of oil in the refrigerants on the mass flow rate through the capillary tube have been discussed. Furthermore, the phenomenon of metastability and the correlations to predict the underpressure of vaporization have also been discussed. The paper provides key information about the range of input parameters viz. tube diameter, tube length, surface roughness, coil pitch and coil diameter, inlet subcooling and condensing pressure or temperature. Other information includes type of refrigerants used, correlations proposed and methodology adopted in the analysis of flow through the capillary tubes of different geometries operating under adiabatic and diabatic flow conditions. It has been found from the review of the literature that there is a lot more to investigate for the flow of various refrigerants through different capillary tube geometries.
77 citations
TL;DR: In this article, an empirical model was developed to size adiabatic and non-adiabatic capillary tubes for small vapour compression refrigeration systems, in particular, household refrigerators and freezers.
Abstract: This paper presents an empirical model that has been developed to size adiabatic and non-adiabatic capillary tubes for small vapour compression refrigeration systems, in particular, household refrigerators and freezers. The model is based on the assumption that the length of a capillary tube is dependent on five primary variables, namely the capillary tube inner diameter, the mass flow rate of the refrigerant in the capillary tube, the pressure difference between highside and lowside, the refrigerant subcooling at capillary inlet and the relative roughness of the capillary tube material. The model is validated with previous studies over a range of operating conditions and is found to agree reasonably well with the experimental data for HFC134a.
53 citations
Journal Article•
TL;DR: In this paper, the performance of capillary tubes having R-407C as the working fluid was examined and a correlation with a mean deviation of 2.78% was proposed to correlate the present test data.
Abstract: This study examines the performance of capillary tubes having R-407C as the working fluid. A correlation with a mean deviation of 2.78% was proposed to correlate the present test data. In addition, the effect of coiling on the performance of a capillary tube was quantitatively investigated. A correlation was proposed to describe the relation between straight and coiled capillary tubes.
29 citations
19 Jan 2008
TL;DR: In this paper, a mathematical model has been developed to predict the performance of a helical capillary tube under adiabatic flow conditions, which can predict the length of the tube for a given mass flow rate.
Abstract: A mathematical model has been developed to predict the performance of a helical capillary tube under adiabatic flow conditions. The proposed model can predict the length of the adiabatic helical capillary tube for a given mass flow rate or the mass flow rate through a given length of capillary tube. The effect of parameters like condensing pressure, degree of subcooling, pitch of helix and the coil diameter has been studied for the flow of refrigerant R-134a through the adiabatic helical capillary tube. A capillary tube selection chart has been developed, using the proposed model, to predict the mass flow rate of refrigerant R-134a through a capillary of size 1.07 mm diameter and 2 m length.
11 citations