Thermal Analysis of a Fiber Optic Cable for a Vertical Farming Application

Feeding the existing 7 billion and ever-growing population around the world urges farmers to adopt alternative ways. Research indicates that the demand for alternative farming will only increase as fertile lands become scarcer each and every year. Emerged from this need, “agritecture,” often called vertical farming, has attracted a great deal of attention recently. Vertical farming is centered around growing plants by adopting methods like hydroponic, aeroponic, or aquaponic and staking the layer vertically up to the sky or going deep in the ground. Lighting is the integral component of the vertical farming systems, which can be natural or artificial and should be provided at a specific intensity and spectrum. The world is already in need of energy to tackle the soaring energy demand due to the rising population and industrialization. Researchers have been trying to utilize alternative sources, and the heat and illumination of the sunlight is always the widespread field of interest. In vertical farming, using hybrid solar lighting can also be an appealing approach. However, the fiber optical cable is one of the critical components of this system, which is used to transmit the light to the luminaire. Since this cable plays a vital role in transmitting the power, the exposure of the surface of the cable to different rays from the directed sunlight is of primary concern to avoid any thermal failure. If not designed properly, the temperatures at the inlet of the fiber optical cable can reach to very high values, resulting in both physical and chemical changes in the cable, and in some cases, local burnings. A literature survey revealed that there are only a few studies that dealt with the thermal management of fiber optical cables. In this study, we analyze the thermal behavior of fiber optical cables for a vertical farming application, which was supported by the United States Department of Agriculture SBIR Phase I program. To do that, we adopted a Finite Element Analysis (FEA) based approach. Before carrying out the full simulations, the simulation methodology was verified by replicating an existing study in the literature. Once confirmed, a full parametric sweep analysis was conducted to see the effects of material and geometric properties of the fiber optical cable on the temperature increase at the inlet. This study is novel in the sense that there are no prior studies that targeted the effects of material and geometric properties on the thermal behavior of the fiber optical cables so the users could make the appropriate choices for the cable selection or could custom design their cables for specific lighting conditions. The results were presented and discussed, and future research directions were indicated.