For an effective capturing of the CO2 from an atmosphere, maximum amount of air needs to be drawn into the system where the process of capturing CO2 takes place by various methods. It is a great challenge for engineers to design the system to draw maximum amount of air for a given rated fan. The flowrate across a fan in a DAC system can significantly impact its efficiency. The fan’s role in a DAC system is to draw atmospheric air into the capture unit, where CO2 is removed. The flowrate determines how much air the DAC system can process in a given amount of time. Higher flowrates allow the system to come into contact with more atmospheric air, which can increase the amount of CO2 captured. However, excessively high flowrates can lead to reduced capture efficiency as higher flowrates may reduce contact time between the air and the CO2 capture materials. the flowrate across the fan in a Direct Air Capture system is a critical parameter that can significantly affect the system’s efficiency. Finding the right balance between flowrate, capture efficiency, energy consumption, and system design is essential for the successful operation of DAC technology. It requires careful consideration and optimization to achieve balanced flow rate with enhanced efficiency in capturing CO2 while minimizing operational costs and energy consumption.

Vias3D modelled and performed CFD simulation to improve the flow rate by making design modifications in shroud for the same fan geometry. The simulation is performed in PowerFLOW simulation software based on Lattice Boltzmann Method (LBM). LBM is a meshless approach and based on fluid particle interactions instead of assuming fluid as continuum. So, the simulation domain is discretised into Lattice grid and the fluid properties are calculated at lattice points based on particle collisions and interactions. 

The air entering the DAC system is assumed to be an ideal gas with the pressure inlet condition since the flow is induced because of the suction created by the fan where pressure difference occurs between inlet and fan. The carbon capturing material is modelled as porous medium with the pressure drop across it and the fan is making 400 revolutions per minute. The base model of the shroud is considered in rectangular shape of 24 ft x 20 ft. The model is able to generate 16.4 cfm of flow rate across the fan. The new model is considered with the design modifications in the shroud and modelled as square shape of 20 ft x 20 ft. With the same conditions as base model, new model is identified to generate 24.1 cfm of flow rate across the fan. Modification in the shroud design is observed to improve the flow rate across the fan by ̴47%.