A Capillary Tube-Refrigerant Charge Design Methodology for Household Refrigerators-Part II: Equivalent Diameter and Test Procedure (original) (raw)
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International Journal of Refrigeration, 2014
In this work the thermodynamic behaviour of a household refrigerator was experimentally studied by simultaneously varying the refrigerant charge and the expansion restriction. A special charging device was designed and constructed for this purpose comprised of a cylinder, a load cell and two solenoid valves. In addition, the original capillary tube was replaced with a larger-diameter capillary tube and installed in series with a metering valve. The expansion restriction was varied by adjusting the capillary tube-metering valve pair to settings higher and lower than that of the original system. A total of 95 energy consumption measurements were recorded with different combinations of refrigerant charge and expansion restriction. A minimum energy consumption region comprised of several combinations of refrigerant charge and expansion restriction was clearly identified. It was also observed that an improper combination of expansion restriction and refrigerant charge may increase the energy consumption by up to 30%.
2016
In this paper, thermodynamic performance analysis and optimization of a domestic refrigerator were experimentally carried out by simultaneously varying the refrigerant charge (wr) and the capillary tube length (L). Continuous running and cycling tests were performed on a domestic refrigerator under tropical conditions using three refrigerants (R12, LPG and R600A) with different capillary tube lengths and various charges. The results show that the design temperature and pull-down time set by ISO for small refrigerator are achieved earlier using refrigerant charge 60g of LPG with 1.5m capillary tube length. The highest COP (4.8) was obtained using 60g charge of LPG with L = 1.5m. The average COP obtained using LPG was 1.14% and 15.09 % higher than that of R600a and R12 respectively. Based on the results of this study, R600a offered lowest power consumption. The compressor consumed 20 % less power compared to LPG and 32% less power than R12 in the system. In conclusion, the system perf...
Influence of the capillary pipe geometry on the energy efficiency of household refrigerator
2020
The energy efficiency of household refrigerating appliances was measured according to EN TSO15502. A Liebherr TKP 1650 built-in Domestic refrigerator is used to determine the influence of the capillary pipe geometry. The temperatures at the injection site of the refrigerant, the inlet and outlet of the evaporator receiver were measured. The obtained results show that there is no universal optimal geometry of the capillary pipe. There is no element of the refrigeration cycle whose change has no effect on the refrigerant flow rate passing through the capillary pipe. A change in the geometry of capillary pipe affects all other components of the refrigeration cycle and can greatly improve or impair the efficiency of the refrigerator. The potential for switching from one to two different geometries of the capillary pipe is approximately 8% improvement in energy consumption. Possible implementation should take into account the potential savings - 8% and the life cycle of the particular ap...
Investigation of Household Refrigerator System with Varied Capillary Tube Length
Journal of Physics: Conference Series, 2019
In this paper, the performance of R600a was investigated in a household refrigerator originally designed to work with R134a using varied capillary tube length (1.0, 1.15, 1.30 and 1.45 m). The refrigerator was instrumented with four thermocouples at the inlet and outlet of the major components. Also, two pressure gauges were connected to the compressor to measure the suction and discharge of the compressor. The experimental results were used to evaluate the performance of the system. The results showed that at optimal capillary tube length the COP and cooling capacity of R600a in the system increased with 45% and 4.2% respectively and the power consumption reduced with 25% using 1.30 m varied capillary tube length compared to R134a. Conclusively, R600a can serve as a retrofit in the household refrigerator systems originally designed to work with R134a refrigerant.
2016
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 consideri...
Scientific Reports
The household heating and cooling system often use the capillary device. The use of the helical capillary eliminates the need for lightweight refrigeration devices in the system. Capillary pressure is noticeably affected by the capillary geometric parameters, such as length, mean diameter, and pitch. This paper is concerned with the effects of the capillary length on the performance of the system. Three separate length capillary tubes were used in the experiment. The data on R152a were studied under various conditions to assess the impact of varying the length. Maximum COP is obtained at an evaporator temperature of − 12 °C and capillary length of 3.65 m. The result is drawn that the system performance enhances when the capillary length is improved to 3.65 m when compared to 3.35 m and 3.96 m. As a result, as the capillary length increases up to a specific amount, the system's performance improves. The findings from the experiment were compared with those from the computational ...
2006
This study compares the performance characteristics of a household refrigerator equipped with an Electronic Expansion Valve (EEV) with those with a capillary tube. A 513-liter top-mount refrigerator, originally equipped with a capillary tube, was retrofitted with a Pulse Width Modulated (PWM) expansion valve and extensively tested. Comparative analyses were performed based on standardized pull-down and energy consumption tests, carried out at three ambient temperatures (18°C, 32°C and 43°C) and with three compressor speeds (2000 rpm, 3600 rpm and 4500 rpm). It was shown that the EEV system showed better performance in terms of energy consumption, as compared with the capillary tube system, only at high cooling loads (ambient temperature of 43 o C) and at low cooling capacities (compressor speed of 2000 rpm). For a wide range of operating conditions the pull-down times of both systems were kept within a difference band of ± 3%.
2016
Miller cycle engines are one of the popular engine concepts that are available for improving performance, reducing fuel consumption and NO x emissions. There are many research studies that investigated the modification of existing conventional engines for operation on a Miller cycle. In this context, a comparative performance analysis and optimization based on exergetic performance criterion, total exergy output and exergy efficiency has been carried out for an irreversible DualeMiller Cycle cogeneration system having finite-rate of heat transfer, heat leak and internal irreversibilities. The EPC (Exergetic Performance Coefficient) criterion defined as the ratio of total exergy output to the loss rate of availability. Performance analysis has been also extended to the OttoeMiller and Diesel-Miller cogeneration cycles which may be considered as two special cases of the DualeMiller cycle. The effect of the design parameters such as compression ratio, pressure ratio, cutoff ratio, Miller cycle ratio, heat consumer temperature ratio, allocation ratio and the ratio of power to heat consumed have also been investigated. The results obtained from this paper will provide guidance for the design of DualeMiller Cycle cogeneration system and can be used for selection of optimal design parameters.
International Journal of Refrigeration-revue Internationale Du Froid, 2019
In this study, two types of mini-channel condenser are integrated into a household refrigerator in order to increase the performance of the system. Since the integration process requires the substitution of capillary tube which will be followed by charging a different amount of refrigerant, this work focuses on finding the right amount of the refrigerant and the right size of the capillary as well. This experimental study is carried out on a commercial household refrigerator in a climatic chamber with respect to IEC standards. During the experiments, two types of mini-channel condensers have been analyzed with five different capillary lengths and five varying coolant amounts in order to find the best combination for better performance. The outcomes of the study release the thresholds for either capillary length or refrigerant amount, which are 3.25 m and 50 g respectively, that will enlighten the further studies on the same investigations.