Reactor Tubing

The solar receiver tubing must have a specified length so that photosynthetic growth can be optimised. It has been shown that the maximum tube length relies on three parameters: liquid velocity, dissolved oxygen concentration and the rate of oxygen production by photosynthesis. Generally, a tube run in a photobioreactor should not surpass 80 m. However, the maximum length of tubing is dependent on solar inten­sity, biomass concentration, liquid flow rate and initial oxygen concentration at the tubing entrance [22]. Molina Grima et al. [23] states that “other than “scale up” by multiplication of identical tubular modules, the only way to increase volume is by increasing length and/or diameter”. Ten years on, the debate over scale-up is still prevalent, with no clear solution readily available. A possible solution to scale-up is to make use of current cultivation designs and employ several cultivation units to produce a significant amount of biomass. However, the process must produce enough biomass such that it will offset extensive equipment costs.