Thermohydraulic and biologic model-based control
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Solution Overview
Problem
Current methods for controlling bacterial activity in fluid distribution systems, such as hot water and HVAC systems, face challenges in balancing energy efficiency with effective bacterial suppression, particularly due to the high energy demand for thermal treatments required to prevent Legionella pneumophila growth, which often results in inefficient heat dissipation and increased energy consumption.
Innovation Solution
A control unit that regulates heating and de-bacterization in fluid systems by sensing temperature and flow rates, modeling bacterial growth, and predicting bacterial concentrations to dynamically adjust thermal treatments, thereby reducing energy consumption while maintaining safety and comfort temperatures between 37° C. and 45° C., using a combination of thermal, chemical, electrochemical, or UV-based de-bacterization methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal treatments are used for bacterial pasteurization to maintain temperatures above 60°C, then bacterial control effectiveness is improved, but energy consumption increases
Solution Approach 1:
The system dynamically adjusts water temperature based on real-time bacterial concentration measurements and predictive modeling. Instead of maintaining a fixed high temperature (60°C), the controller modulates temperature to match actual bacterial risk levels, reducing energy consumption when bacterial threats are low while ensuring adequate temperatures when threats are high.
Solution Approach 2:
The system changes the temperature parameter dynamically based on bacterial concentration predictions. The controller adjusts temperature setpoints according to modeled bacterial growth rates and predicted concentrations, allowing the system to operate at lower temperatures when safe and raise temperatures only when bacterial risk requires it, thereby resolving the contradiction between temperature maintenance and energy efficiency.
2Reliability
If water is produced and stored at temperatures above 60°C to prevent Legionella growth, then bacterial safety is improved, but heat dissipation efficiency deteriorates
Solution Approach 1:
The system dynamically adjusts storage and distribution temperatures based on real-time bacterial monitoring and predictive models. By lowering temperatures when bacterial growth risk is low and only maintaining high temperatures when necessary, the system reduces unnecessary heat dissipation losses while preserving bacterial safety when risks are present.
Solution Approach 2:
The system uses the natural heat dissipation that was previously considered a loss (cooling water below safe temperatures) as a beneficial feature by allowing temporary temperature reductions when bacterial risk is low, thereby converting what was a safety compromise into an energy-saving opportunity through intelligent control.
3Reliability
If the temperature difference between DHW system and environment is increased to 60°C-40°C for bacterial control, then bacterial suppression is improved, but heat dissipation loss increases
Solution Approach 1:
The system dynamically adjusts the temperature differential based on bacterial concentration predictions and environmental conditions. Instead of maintaining a fixed large temperature difference (60°C-40°C), the controller reduces the differential when bacterial risks are low and increases it only when necessary, thereby minimizing heat dissipation losses while maintaining effective bacterial suppression when needed.
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
This approach allows for efficient and safe bacterial control in fluid distribution systems with reduced energy demand, minimizing bacterial contamination and energy waste by tailoring heating and de-bacterization strategies based on real-time data and predictive modeling, ensuring Legionella concentrations remain below predetermined thresholds.
Implementation Method 1
at least one sensing unit for sensing a first temperature of the fluid at a first location in the fluid system as a function of time
Implementation Method 2
the module being programmed for modelling bacterial growth in the fluid throughout the fluid system as function of time based on the obtained second temperatures
Implementation Method 3
a heater can set a temperature and heating regime which gives at least the minimum temperature required for user comfort while at the same time working under low energy consumption conditions
Implementation Method 4
thermal treatments are used for bacterial pasteurization, which increases energy demand
Data Source
AI summary
A control unit (100, 120, 130) adapted to regulate at least one de-bacterisation unit (201) of a fluid system (200, 210, 230) is described. The fluid system (200, 210, 230) comprises the de-bacterisation unit, a production unit for producing a heated fluid heated to a predetermined temperature, at least one pipe for transporting the fluid from the production unit to at least one fluid outlet, at least one fluid outlet and at least one sensing unit for sensing a temperature of the fluid at a first location in the fluid system as a function of time. The control unit (100, 120, 130) includes a module (101, 124) adapted for obtaining temperatures at a plurality of locations in the fluid system as function of time and programmed for modelling bacterial growth in the fluid in the fluid system as function of time based on the obtained temperature in the system and for predicting, based on the modelling, the bacterial concentration at the at least one fluid outlet over time. The control unit is being adapted for driving the de-bacterisation unit, The control unit is being adapted for determining, based on said predicted bacterial concentration over time obtained by the module (101, 124), moments in time when the bacterial concentration reaches a predetermined value in the fluid system and for, in reply thereto, driving at these moments in time the de-bacterisation unit (201) so as to reduce bacterial concentration in the fluid system (200, 210, 230).