System for heating water for domestic use
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Solution Overview
Problem
Sanitary water heating systems face inefficiencies due to high return temperatures of heat transfer liquids, which negatively impact the thermal source's efficiency and lead to peak energy production issues.
Innovation Solution
A control method and electronic control unit are implemented to manage the bypass valve and heat transfer liquid distribution, ensuring the tank maintains a balance of hot and cold heat transfer liquids, thereby regulating the return temperature and reducing peak energy production demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the tank stores hot heat transfer liquid to preheat cold domestic water and clip peak energy production, then peak energy production is reduced, but the return temperature may become too high which deteriorates thermal source efficiency
Solution Approach 1:
The tank is divided into two distinct zones: an upper zone for storing hot heat transfer liquid and a lower zone for storing cold heat transfer liquid. This segmentation allows independent management of hot and cold fluids, enabling the system to clip peak energy production using hot liquid while maintaining low return temperature by selectively withdrawing cold liquid, thus resolving the contradiction between energy peak clipping and return temperature control
Solution Approach 2:
Different regions of the tank are assigned different thermal characteristics - the upper zone maintains high temperature for preheating and peak clipping, while the lower zone maintains low temperature for efficient return to the thermal source. This local quality differentiation allows the system to simultaneously achieve peak energy reduction and maintain optimal return temperature for thermal source efficiency
2Productivity
If the tank is completely filled with hot heat transfer liquid to maximize preheating capacity, then preheating performance is improved, but the system loses ability to regulate return temperature when demand fluctuates
Solution Approach 1:
The system dynamically adjusts the volumes of hot and cold heat transfer liquid in the tank zones based on real-time demand conditions. The control unit monitors system needs and actively manages the distribution between hot and cold zones, allowing the tank to adapt its composition - maintaining high preheating capacity when needed while preserving regulatory flexibility to respond to fluctuating thermal demands
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 stabilizes the return temperature, enhances thermal source efficiency, and effectively clips peak energy production, ensuring consistent and efficient energy distribution.
Implementation Method 1
a preheating heat exchanger capable of preheating cold domestic water, by heat exchange with the heat transfer liquid stored in the upper part of the tank
Implementation Method 2
an additional heat exchanger able to maintain the temperature of the domestic hot water circulating in the loop at a temperature above a predetermined Tmin-DHW temperature by heat exchange with the heated coolant
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
This domestic hot water heating system comprises: - a measuring apparatus (130) for a physical quantity representative of a volume of hot heat transfer fluid currently stored in a tank, - a controllable bypass valve (76) capable of adjusting the flow in a bypass conduit (74) capable of diverting at least part of the heat transfer fluid discharged by an auxiliary heat exchanger (20) to bring it to the inlet (12) of a heat source (4) without passing through the tank, - an electronic control unit (90) configured to: • acquire the measurements from the measuring apparatus, and • control, based on the measurements acquired, the bypass valve to increase the flow in the bypass conduit when the volume of hot heat transfer fluid stored exceeds a first predetermined threshold strictly lower than the maximum volume of heat transfer fluid that can be stored in this tank.