On the theoretical prediction of microalgae growth for parallel flow

TL;DR

This paper introduces a nondimensional analytical model for predicting microalgae growth in parallel flow photobioreactors, aiming to unify experimental data and improve understanding of growth mechanisms for biofuel applications.

Contribution

It develops the first nondimensional analytical solution for microalgae growth rate in parallel flow, reducing reliance on empirical fitting and enhancing predictive capability.

Findings

The nondimensional growth rate depends on Reynolds and Schmidt numbers.

The model aligns with experimental data within an order of magnitude.

It provides a theoretical basis for large-scale PBR design.

Abstract

The established microalgae growth models are semi-empirical or considerable fitting coefficients exist currently. Therefore, the ability of the model prediction is reduced by the numerous fitting coefficients. Furthermore, the predicted results of the established models are dependent on the size of the photobioreactor (PBR), light intensity, flow and concentration field. The growth mechanism of microalgae has not clearly understood in PBR cultivation. It is difficult to predict the microalgae growth by theoretical methods, owing to the aforementioned factors. We developed an exploratory bridging microalgae growth model to predict the microalgae growth rate in PBRs by using the nondimensional method which is effectively in fluid dynamics and heat transfer. The analytical solution of the growth rate was obtained for the parallel flow. The nondimensional growth rate expressed as function of Reynolds number and Schmidt number, which can be used for arbitrary parallel flow due to the solution was expressed as nondimensional quantities. The theoretically predicted growth rate is compared with the experimentally measured microalgae growth rate on the order of magnitude. The nondimensional method successfully applied to the microalgae growth problem for the first time. The general nondimensional solution can unify the numerous experimental data for different laboratory conditions, and give a direction for the disorder of the microalgae growth problem. The nondimensional solution may be useful to explain the growth mechanism of microalgae and design large-scale PBRs for microalgae biofuel production. The significance of the work is to give a theoretical foundation and methodology of biological theory of microalgae growth.