Effects of an Air Curtain on the Temperature Distribution in Refrigerated Vehicles Under a Hot Climate Condition

Abstract

Refrigerated vehicle plays an essential role in the cold-chain applications. It directly affects the quality and shelf life of specialized perishable goods. However, the cold energy dissipation caused by natural convection through an open door during partial unloading breaks the isothermal cold environment and notably elevates the air temperature inside the refrigerated container. This temperature rise is harmful to the remaining food. In this study, an air curtain was introduced near the container doorway to attempt to reduce the cold energy dissipation caused by partial unloading. A numerical model was established to explore the effects of the key parameters of the air curtain such as the airflow rate, nozzle width, and jet angle on the air flow and temperature evolution inside the refrigerated container after the door is opened. The numerical results show that the key parameters need to be tailored to form a stable and effective air curtain for preventing the internal cold energy loss or external hot air invasion. An effective and stable air curtain was formed to make the inner air temperature increase only by about 3 °C from the initial temperature of 5 °C after the door was opened, when the jet velocity was set to 2 m/s, the nozzle width was set as 7.5 cm, and the jet angle was set between 0 deg and 15 deg. This work can offer significant guidance for the introduction of an effective air curtain in a refrigerated vehicle to avoid the failure of cold-chain transportation.

Optimization of open refrigerated display cabinet based on different package arrangements

“…Result found that it was 0.12 m 3 s -1 when jet angle was 17.5 o . Similar work can also be found to discuss the impact of jet width [8], jet thickness, and jet length at (discharge air grill) DAG on its performance [9].…”

Air curtain performance: Introducing the adapted separation efficiency

“…As indicated in the above-mentioned overview of previous studies, different indicators have been used to mark the performance of ACs, including heat transfer correlations [8,25,[34][35][36][37]43,44], infiltration or mass transfer correlations [8,26,38,39,41,42], concentration distributions [4,45], temperature distributions [46,47] and jet stability parameters [28,48,49]. However, the most commonly used performance indicator in both the scientific literature and the industry is the 'separation/sealing efficiency' (or 'separation effectiveness') η s (e.g., Ref.…”