Impact of air flow, temperature distribution, and heat transmission in a refrigerator compartment with and without shelves: A numerical approach
1Department of Mechanical Engineering, Khulna University of Engineering & Technology, Khulna, 9203, Bangladesh
J Ther Eng 2024; 10(6): 1590-1606 DOI: 10.14744/thermal.0000880
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Abstract

This study explores the impact of shelf configurations on airflow, temperature distribution, and heat transfer within a refrigerator’s compartment, aiming to optimize natural convection for enhanced energy efficiency and preservation. This analysis assumes a steady-state and laminar air flow to maintain a constant heat transfer rate, where the flow is to be stable with a consistent two-dimensional pattern. Computational fluid dynamics simulations are conducted with AN-SYS Workbench 2020 R1 to model airflow patterns, temperature gradients, and heat transfer mechanisms under various shelf configurations. The effect of shelves on airflow and temperature distribution inside the refrigerant compartment are investigated and compared the results of temperature and air-flow distribution by altering the number of glass plates. The analysis reveals significant temperature stratification: colder air tends to settle at the bottom, while warmer air accumulates at the top. Glass shelves are found to disrupt the primary airflow along the walls, but they also enhance heat transfer by improving airflow near the walls. This results in higher temperatures in the upper sections of the refrigerator compared to the average, which presents challenges for storing temperature-sensitive items regardless of the shelf configuration. The lowest temperature in the compartment is 272.55 K at 0~10 cm from the bottom wall, and the highest is 279.75 K at 95~100 cm, due to the upward rise of hot air and downward sink of cold air. The pressure ranges are from -7.11 × 10-3 to 2.88 × 10-1 Pa for without shelves and -7.95 × 10-3 to 3.07 × 10-1 Pa with four shelves, respectively. Maximum air velocities are 1.87 × 10-2 m/s for without shelves and 1.61 × 10-2 m/s for with shelves. By measuring temperatures, pressure, and air velocities at various points within the compartment maintained at the optimal temperature, the study highlights the impact of air density changes on airflow and temperature distribution. The findings underscore the importance scope of shelf design and placement in minimizing temperature differentials and improving cooling efficiency. The originality of this work lies in advancing beyond conventional forced convection models by exploring temperature stratification and natural convection effects to optimize shelf layout and improve energy efficiency. This study integrates detailed air flow analysis with practical implications for refrigerator design, advancing beyond conventional forced convection systems. Future research could explore alternative shelf materials, optimal configurations, and consumer behavior to further refine refrigeration Technologies for sustainable household use.