Work

Influence of air flow rate on the cooling characteristics of a single and batch apple fruits

Year: 2025

Type: article

Abstract: • Cooling of individual and batch of apples evaluated. • Heat transfer in apple during air-cooling quantified. • Fan air velocity above 2.0 m/s showed a reduced effect on apple cooling. • Heat transfer coefficients of a bin of apples ranged from 2.1 to 7.9 W m −2 K −1 . • Numerical correlation for bin of apples was proposed. Refrigerated storage is crucial for maintaining the quality and safety of highly perishable and seasonal fresh fruit during the postharvest stage. Heat transfer is the primary factor that affects food decay in the storage period. However, cold storage facilities often face challenges with non-uniform airflow and temperature distribution. Therefore, this study aimed to investigate the impact of different cooling rates on heat transfer. It considered factors such as air velocity, apple surface area, initial apple temperature, air temperature, and application of a coating on apples during cold storage. Tests were conducted using a batch of apples stored in a bin as well as individually. These investigations represent the variability of conditions found within cold storage facilities. The results demonstrated that air velocity plays a significant role in the cooling kinetics of apples. Higher air velocities (>2.0 m s −1 ), at the fan outlet, were found to have a lesser pronounced influence compared to lower velocities (<1.0 m s −1 ). Heat transfer coefficients of a bin of apples ranged from 2.1 to 7.9 W m −2 K −1 , for the corresponding average air speed of 0.05 and 0.31 m s −1 within the bin. Numerical correlations were generated for the single apple as well for the bin of apples. These findings contribute to a better understanding of how to store fresh produce effectively and suggest that adjusting the airflow in cooling facilities during different cooling phases could be guided by thermal analysis of fresh produce, potentially leading to energy-saving strategies.

Source: Thermal Science and Engineering Progress

DOI: 10.1016/j.tsep.2025.103257