Quantitative Perturbation Analysis of Plant Factory LED Heat Dissipation on Crop Microclimate

Abstract

Regulating plant factories is crucial for optimal plant growth and yield. Although LEDs (light-emitting diode) are called cold light sources, more than 80% of the heat is still emitted into the surrounding environment. In high-density vertical agricultural facilities, the crop canopy is positioned close to the light source to maximize light absorption and promote plant growth. LED heat dissipation can cause disturbances in the microclimate of crop canopies, which can lead to tip burn disease in plant crops and result in economic losses for plant factories. CFD (computational fluid dynamics) is used as the main technical tool to simulate and optimize the environment of agricultural facilities. This study utilized Star-ccm+ to simulate the microclimate of plant factories under different light treatments. Uniformity coefficient UI and disturbance coefficient θ were proposed to quantitatively analyze LED heat dissipation’s impact on microclimate. In the T5 treatment group, which had a PPFD of 350 μmol/m2·s in the growth zone and 250 μmol/m2·s in the seedling zone, the relative humidity (RH), airflow, and temperature uniformity coefficients UI were 0.6111, 0.3259, and 0.5354, respectively, with corresponding disturbance coefficients θ of 0.0932, 0.1636, and 0.1533. This study clarifies the degree of perturbation caused by LED heat dissipation on microclimate, providing a theoretical basis for regulating plant factory light and promoting sustainability.

Design and Optimization of Air Inlet in Cuttings Incubator

“…Meanwhile, cuttings require humidity control, which is achieved in greenhouses through intermittent misting to control the vapor pressure deficit (VPD) [65]. VPD is a key regulator of transpiration [66]; various studies have discussed the interaction of VPD, transpiration, and airflow in chamber CFD modeling [10,23,39]. In conclusion, the flow field simulation of the incubator can be further optimized to adapt to cuttings from multiple types of plants in future studies.…”

“…A four-channel thermocouple thermometer (model: TA612C, Suzhou Tasi Electronic Industrial Co., Ltd., Suzhou, Jiangsu, China) was utilized to measure the surface temperature of the thermostatic plate, which recorded the time of temperature stability. Once a stable temperature was attained, the Uniformity Index (UI) was calculated according to Equation (4) [23]:…”

“…For crop cultivation areas, porous medium models based on Darcy's law have been used to describe the impact of plants on airflow [21]. The influence of various devices in agricultural buildings on the flow field can also be studied through CFD, such as the heat generated by LED light sources and its disturbance to airflow [22,23], as well as the impact of heating devices as energy sources on the airflow distribution within chambers [24,25].…”

Improvement of Environmental Uniformity in a Seedling Plant Factory with Porous Panels Using Computational Fluid Dynamics

“…Studies on the aerodynamic approaches of plant factories have been conducted to enhance productivity through structural analysis [18]. Internal environmental uniformity has been analyzed to improve the stable crop productivity through the uniformity of air distribution and temperature and humidity in a fully controlled plant factory [19]. In crop cultivation, the optimal air velocity range was suggested to be 0.1 to 0.5 m/s, resulting in enhanced product quality and preventing the occurrence of tip-burning phenomena [20].…”