Identifying effective parameters on capillary tube performance with HCFCs, HFCs blends, and hydrocarbon refrigerants: Numerical assessment

• Published in: Thermal science and engineering progress Vol. 54; p. 102825
• Main Authors: Salman, Ali D., Al Jubori, Ayad M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-09-2024
• Subjects: Capillary tube; Choke flow; Two-phase flow; Zeotropic and hydrocarbon refrigerants; Zeotropic and hydrocarbon refrigerants; Choke flow; Two-phase flow; Capillary tube
• ISSN: 2451-9049
• DOI: 10.1016/j.tsep.2024.102825

•R22, R290, R404A, R407C, R410A and R507A through the ACT were considered.•The design parameters and operating conditions for a group of refrigerants are studied.•The proposed model is validated against experimental data.•The performance of an ACT in a refrigeration system is affected by different parameters.•ACT critical length was directly proportional with the degree of subcooled.
This work offers a comprehensive numerical evaluation of the performance of capillary tube utilizing different refrigerants, including HCFCs, HFCs blends (Zeotropic, Azeotropic), and hydrocarbon, such as such as R22, R404A, R407C, R410A, R507A, and R290 refrigerants to predict the critical length of the adiabatic capillary tube. Utilizing a comprehensive thermodynamic model is applied to simulate the behavior of different refrigerants. Moreover, the effective design parameters based on the internal diameter for the adiabatic capillary tube (ACT), inside surface tube roughness, degree of subcooled, metastable region, condenser diameter, design of evaporator pressure (at critical length), condenser operating pressure, and refrigeration capacity are considered. The numerical model is developed based on the governing equations for mass, momentum, and energy, while a specified empirical equations are employed to represent each of the friction factor for single-and-two phase flow and metastable region. The results showed that the longest length of the ACT of 10.5 m revealed with R410A at mass flow rate of 8 g/s compared with 0.25 m at mass flow rate of 16 g/s for R290. Also, the results showed that the minimum value of friction factor of 0.0189 for R410A compared with maximum value of 0.0208 for R407C. The developed model is validated with available experimental results and models under different operation conditions and is found expectable with a good agreement. Where the standard error for different refrigerant with range value between (2.774% to 3.677%). However, the model represents accurate prediction the flow behavior and the thermal performance of the ACT.