Sloped Shallow Algae Cultivation Using Translating Hydraulic Jump Waves
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Solution Overview
Problem
Existing algae cultivation systems face challenges in achieving high productivity while maintaining low capital and operating costs, particularly in scalable systems. Conventional closed photobioreactors achieve high productivity but are costly and not scalable, while open systems like raceways have lower costs but lower productivity and are limited in scale.
Innovation Solution
The introduction of periodic bore waves or translating hydraulic jump waves in algae cultivation systems enhances algal growth circulation, achieving good mixing independent of base fluid flow turbulence. These waves can be generated using various techniques, including increasing the fluid level, mechanically accelerating fluid flow, or using pumping devices with variable speed drives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional closed photobioreactors are used to achieve high productivity, then productivity is improved, but capital and operating costs increase and scalability is reduced
Solution Approach 1:
The patent employs inexpensive, easily constructible earthen raceways with plastic liners instead of expensive closed photobioreactors. These simple open systems can be rapidly deployed and modified, providing a cost-effective alternative that maintains scalability while achieving improved productivity through the wave mixing mechanism.
Solution Approach 2:
The patent utilizes hydraulic wave propagation through the algae culture fluid to achieve mixing and circulation. By generating periodic waves that travel through the raceway, the system creates turbulent mixing and vertical circulation without requiring complex mechanical mixers or high-energy pumping systems, thus reducing operational costs while maintaining high productivity.
2Device complexity
If open raceway systems are used to reduce capital and operating costs, then costs are reduced, but productivity and scalability are limited
Solution Approach 1:
The patent implements periodic wave generation in the raceway systems, where waves are created at regular intervals to continuously circulate and mix the algae culture. This periodic hydraulic action enhances mass transfer, prevents sedimentation, and maintains uniform nutrient distribution, thereby significantly improving productivity in low-cost open raceway systems without requiring continuous high-energy input.
Solution Approach 2:
The patent changes the flow regime parameter by introducing periodic wave motion instead of steady laminar flow. This parameter change transforms the mixing mechanism from diffusion-dominated to advection-dominated with turbulent fluctuations, enhancing mass transfer coefficients and productivity while maintaining the simplicity and low cost of open raceway systems.
3Length of stationary object
If very shallow cultivation systems are used to reduce depth, then depth is reduced, but engineered smooth surfaces and high slopes are required increasing capital and energy costs
Solution Approach 1:
The patent allows the raceway bottom to utilize natural ground irregularities and settling characteristics rather than requiring engineered smooth surfaces. The periodic wave mixing mechanism compensates for depth variations and irregularities, enabling the system to self-adjust to natural terrain variations while maintaining effective mixing and productivity, thus eliminating the need for expensive engineered surfaces and high slopes.
4Productivity
If high fluid velocities are used to improve mixing, then mixing is improved, but energy consumption increases
Solution Approach 1:
The patent employs periodic wave generation instead of continuous high-velocity flow to achieve mixing. The waves create intermittent turbulent mixing events that are sufficient for mass transfer and circulation, allowing the system to operate at lower average velocities and reduce continuous pumping energy consumption while maintaining effective mixing during the wave passage.
Solution Approach 2:
The patent utilizes the phase transition of the flow regime from laminar to turbulent during wave passage. The periodic conversion between flow phases creates intense mixing during the turbulent phase while allowing energy recovery during the laminar phase, reducing overall energy consumption compared to maintaining continuous turbulent flow at high velocities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The use of bore waves allows for higher productivity in algae cultivation, reducing the need for high slopes or active mixers, and lowering operational energy usage. This approach enables the operation of shallow algae cultivation systems with reduced capital and operating costs, while maintaining or exceeding the productivity of conventional systems.
Implementation Method 1
a translating hydraulic jump is generated at the wave front, herein referred to as a translating hydraulic jump wave or bore wave
Implementation Method 2
The waves generate highly turbulent mixing with extensive vertical mixing that persists well after the wave passes
Implementation Method 3
periodic generation of one or more waves that move fluid through the cultivation systems
Implementation Method 4
Shallow algae cultivation systems can also be attained and operated without the need for high slopes, or the need for active mixers to induce intensive turbulence
Data Source
AI summary
An algae cultivation system includes generating a translating hydraulic jump wave that travels across a gas-liquid interface of an algae cultivation fluid contained in the algae cultivation system. The translating hydraulic jump wave has Froude number greater than 1.