New empirical correlations for sizing adiabatic capillary tubes in refrigeration systems

2012 ◽  
Author(s):  
S. Shodiya ◽  
A. A. Aahar ◽  
N. Henry ◽  
A. N. Darus
Keyword(s):  
Empirical Correlations ◽  
Capillary Tubes

Assessment of a Simpler Friction Factor in an Algebraic Solution for Adiabatic Coiled Capillary Tubes

2020 ◽  
Vol 28 (04) ◽  
pp. 2050033
Author(s):  
Thiago Torres Martins Rocha ◽  
Sara Isabel De Melo Resende ◽  
Hélio Augusto Goulart Diniz ◽  
Fernando Antônio Rodrigues Filho ◽  
Raphael Nunes De Oliveira
Keyword(s):  
Friction Factor ◽  
Algebraic Solution ◽  
Maximum Deviation ◽  
Empirical Correlations ◽  
Capillary Tubes ◽  
Average Deviation ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Rms Error ◽  
Dimensionless Correlations

In this work, the performance of an existing algebraic solution for adiabatic coiled capillary tubes, in subcritical cycles, is investigated. However, the C-M&N friction factor, commonly used, was replaced by Schmidt friction factor, which is less complex. Two existing dimensionless correlations were also evaluated for comparison. To assess the effect of altering the friction factor, experimental data collected in the literature were used as reference. Analyzing the present results and that with C-M&N friction factor, it was observed that adopting the Schmidt friction factor does not cause a relevant impact on the solution. The deviations of the predicted versus experimental mass flow rates were comprised in a range between –8% and 12%, with average deviation (AD), absolute average deviation (AAD) and root mean square (RMS) error of –0.1%, 2.7% and 3.4%, respectively. The empirical correlations presented unsatisfactory results, with maximum deviation around 40%. Therefore, it was concluded that using the Schmidt friction factor is adequate to reduce the complexity of the algebraic solution and to maintain the accuracy.

EMPIRICAL CORRELATIONS FOR SIZING ADIABATIC CAPILLARY TUBES USING CONVENTIONAL REFRIGERANTS AND THEIR ALTERNATIVES

2015 ◽  
Vol 46 (5) ◽  
pp. 483-501
Author(s):  
Shodiya Sulaimon ◽  
Azhar Abdul Aziz ◽  
Henry Nasution ◽  
Amer Nordin Darus
Keyword(s):  
Empirical Correlations ◽  
Capillary Tubes

AN EVALUATION OF CONSTITUENT CORRELATIONS FOR PREDICTING REFRIGERANT CHARACTERISTICS IN ADIABATIC CAPILLARY TUBES

2010 ◽  
Vol 18 (02) ◽  
pp. 131-139 ◽  
Author(s):  
DEBASISH SARKER ◽  
LYUN-SU KIM ◽  
KI-DONG SON ◽  
JI HWAN JEONG ◽  
KEUN SUN CHANG
Keyword(s):  
Capillary Flow ◽  
Capillary Tube ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Physical Models ◽  
Tube Length ◽  
Empirical Correlations ◽  
Capillary Tubes ◽  
Two Phase ◽  
Capillary Model

Capillary tubes are widely used as a refrigerant flow control device in small refrigeration systems. Since the flow behavior inside the capillary tube is complex, many physical models are necessary to predict the characteristics of the refrigerant flow in a capillary tube. In the present paper, refrigerant flow characteristics inside the capillary tube have been studied to find out recommended empirical correlations of influential parameters. A numerical capillary model is developed to predict the refrigerant characteristics. Various empirical correlations regarding single-phase friction factor, two-phase viscosity, two-phase frictional multiplier and metastable flow are examined using this numerical capillary model. Calculated results are compared with experimental data to examine the accuracy in terms of required capillary tube length and mass flow rate. Based on the comparison, recommended correlations are selected to be used for capillary flow analysis.

NUMERICAL SIMULATION FOR FLOW ANALYSIS IN NON-ADIABATIC CAPILLARY TUBES

2017 ◽  
Author(s):  
Hugo Augusto ◽  
Felipe Silva ◽  
Caio Vinicios Juvencio da Silva ◽  
Maycon Ferreira Silva ◽  
Leonardo José Cavalcante Vasconcelos
Keyword(s):  
Numerical Simulation ◽  
Flow Analysis ◽  
Capillary Tubes

Effects of Sonication Time on the Stability and Viscosity of Functionalized MWCNT-Based Nanolubricants

2020 ◽  
Vol 16 (4) ◽  
pp. 639-654
Author(s):  
Ahmet Selim Dalkilic ◽  
Bedri Onur Küçükyıldırım ◽  
Ayşegül Akdoğan Eker ◽  
Faruk Yıldız ◽  
Altuğ Akpinar ◽  
...  
Keyword(s):  
Effective Viscosity ◽  
Mass Concentration ◽  
Measured Data ◽  
Sonication Time ◽  
Empirical Correlations ◽  
Thermal Systems ◽  
The Stability ◽  
Rotary Viscometer ◽  
Functionalized Mwcnts ◽  
Measured Viscosity

Background: Active scholars in the nanofluid field have continuously attempted to remove the associated challenge of the stability of nanofluids via various approaches, such as functionalization and adding a surfactant. After preparing a stable nanofluid, one must measure the properties, as this is vital in the design of thermal systems. Objective: Authors aimed to investigate the stability and viscosity of refrigeration lubrication oilbased nanofluids containing functionalized MWCNTs. The effects of concentration and temperature on viscosity were studied. Furthermore, the present study focused on the effect of sonication time on the stability and viscosity of the prepared samples. Methods: After the preparation of chemically functionalized MWCNTs, solutions were dispersed with an ultrasonic homogenizer for 2, 4 and 8 hours sonication at maximum power. Viscosity measurements for all samples were made 10 minutes after sonication by adjusting the proper spinning velocity using a digital rotary viscometer. Results: The first part deals with the stability of the nanofluid as a nanolubricant, and the second one investigates the viscosity of the nanofluid and the effects of various parameters on it. The last one is related to the validation of the measured viscosity values by means of well-known empirical correlations. The measured data are given for validation issues. Conclusion: The samples will have higher stability by increasing the time of sonication. The viscosity of a nanofluid does not change with the increase of sonication time to two hours and higher. Up to mass concentration of 0.1%, the effective viscosity increases with adding nanotubes linearly.

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