This study assesses thermal uniformity at the crop cultivation height of 1.5 m and the heating load of a 40-ft container-type smart farm (interior dimensions: 9,600 mm × 2,290 mm × 2,557 mm) maintained at an indoor setpoint of 25℃. Using computational fluid dynamics (CFD), we analyzed the impacts of outdoor temperatures (-30℃, -20℃, -10℃, and 0℃), insulation thicknesses (150 mm, 200 mm, 250 mm, and 300 mm), and the number of fan coil units (FCUs; 1, 2, and 3). As outdoor temperatures rose from -30℃ to 0℃, the temperature deviation at crop height decreased from 10.0℃ to 4.6℃, while the heating load decreased from 833.0 W to 378.8 W, representing a 54.5% reduction. Increasing insulation thickness from 150 mm to 300 mm lowered the temperature deviation from 10.0℃ to 5.3℃ and the heating load from 833.0 W to 433.4 W. Adding more FCUs—first from one to two, then to three—reduced the temperature deviation to 7.1℃ and 6.1℃, respectively. While changes in insulation thickness effectively decreased both heating load and temperature deviation, increasing the number of FCUs had minimal impact on heating load but provided a greater reduction in temperature deviation than increasing insulation thickness from 150 mm to 250 mm. In extremely cold conditions, optimizing insulation performance and internal airflow should be tailored to the container’s area and geometry.
Kang et al. (Fri,) studied this question.