Dissolved Oxygen Enrichment for Irrigation Water Set-Point Control
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Solution Overview
Problem
Existing oxygenation systems for irrigation water in soilless cultivation fail to maintain the required dissolved oxygen levels throughout irrigation cycles due to a lag time in reaching set-point values, negatively impacting plant health and productivity.
Innovation Solution
A method involving a boosted oxygen injection during the initial part of irrigation phases, followed by a nominal flow rate to quickly achieve and maintain desired dissolved oxygen levels, using a flow sensor and dual oxygen supply lines with timed electrically operated valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If oxygen injection is maintained at nominal flow rate throughout the irrigation phase, then operating costs are reduced, but dissolved oxygen levels fail to reach set-point values during the irrigation phase
Solution Approach 1:
The system performs preliminary oxygen injection at a boosted flow rate during an initial period (5-15 minutes) at the start of the irrigation phase, before the nominal irrigation period begins. This preliminary action ensures that when irrigation starts, the dissolved oxygen levels are already at or near the set-point value, eliminating the lag time problem and ensuring optimal oxygen levels throughout the entire irrigation phase without requiring continuous high-rate oxygen injection.
2Reliability
If oxygen injection starts at nominal flow rate, then energy consumption is minimized, but there is a lag time of 5-15 minutes to reach set-point dissolved oxygen levels
Solution Approach 1:
The system performs preliminary oxygen injection at a boosted flow rate during an initial period (5-15 minutes) at the start of the irrigation phase, before the nominal irrigation period begins. This preliminary action ensures that when irrigation starts, the dissolved oxygen levels are already at or near the set-point value, eliminating the lag time problem and ensuring optimal oxygen levels throughout the entire irrigation phase without requiring continuous high-rate oxygen injection.
3Quantity of substance
If boosted oxygen injection is applied throughout the entire irrigation phase, then dissolved oxygen levels are maintained optimally, but operating costs increase significantly
Solution Approach 1:
The system performs preliminary oxygen injection at a boosted flow rate during an initial period (5-15 minutes) at the start of the irrigation phase, before the nominal irrigation period begins. This preliminary action ensures that when irrigation starts, the dissolved oxygen levels are already at or near the set-point value, eliminating the lag time problem and ensuring optimal oxygen levels throughout the entire irrigation phase without requiring continuous high-rate oxygen injection.
Solution Approach 2:
The system uses periodic action by switching between two distinct oxygen injection rates: a boosted flow rate during the initial period (5-15 minutes) and a nominal flow rate during the remainder of the irrigation phase. This periodic modulation of the oxygen injection rate optimizes both dissolved oxygen levels and operating costs by applying high-rate injection only when necessary to reach set-point values, then maintaining levels with lower-rate injection.
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
Enhances oxygen delivery efficiency, ensuring plants receive optimal oxygen levels throughout irrigation, thereby improving plant health and yield without increasing costs significantly.
Implementation Method 1
oxygen enrichment of irrigation water using air limits the content to a maximum of 10 mg/L, whereas dissolved-oxygen enrichment using pure oxygen (O2) makes it possible to reach much higher contents (typically 40 mg/L)
Data Source
AI summary
A method and equipment for plant cultivation, where the plants are supplied with water, over irrigation phases of specific duration spread over a 24 h day, which water has a given content of dissolved oxygen, characterized in that use is made of a system for boosting the injection of oxygen (or of an oxygen-containing gas mixture) in the irrigation water over a first period, of given duration, of one or some of the irrigation phases in question, and in that the remainder of the time of said irrigation phase(s) in question is characterized by a content of dissolved oxygen in the water which is nominal, i.e. lower than the boosted content of the first period.