Two-Stage Domestic Hot Water Heating for Low Return Heat Loss
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Solution Overview
Problem
Existing systems for heating drinking water in buildings are inefficient, particularly in variable temperature conditions, and often require excessive energy consumption and complex control systems to maintain optimal heating return temperatures.
Innovation Solution
A method utilizing a home station with two complementary heating stages: a water-water heat exchanger and an electric post-heater, allowing for efficient heating of drinking water to domestic hot water temperature, with the option to recover thermal energy from waste water, and a decentralized control system that adapts to consumption and status variables for optimized energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a single heating stage is used to heat drinking water, then the system is simple, but it cannot efficiently adapt to variable temperature conditions and consumes excessive energy
Solution Approach 1:
The heating system is divided into two distinct heating stages: a first heating stage that heats drinking water to an intermediate temperature, and a second heating stage that heats the water from intermediate to final temperature. This segmentation allows each stage to operate more efficiently, with the first stage utilizing waste heat from heating water and the second stage providing precise temperature control, thereby reducing overall energy consumption while maintaining manageable system complexity through modular design.
2Loss of energy
If heating water temperature is maintained at constant high level, then hot water is always available, but heat energy is wasted in the heating return
Solution Approach 1:
The system dynamically changes the temperature parameter of the heating water based on actual demand. Instead of maintaining a constant high temperature, the first heating stage adjusts the intermediate temperature according to the temperature of incoming drinking water and demand conditions, while the second stage ensures the final temperature meets requirements. This parameter adaptation reduces heat energy loss in the return line while reliably providing hot water when needed.
3Use of energy by moving object
If thermal energy from waste water is recovered, then energy efficiency improves, but the system complexity increases
Solution Approach 1:
The system recovers thermal energy from waste water by routing it through the first heating stage, where it heats incoming drinking water before the water is discharged. This recovery process captures otherwise wasted thermal energy and puts it to useful effect, significantly improving overall energy efficiency. The complexity increase is managed through integrated design where the recovery function is combined with the existing heating infrastructure.
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 ensures reliable provision of domestic hot water at variable conditions, optimizes energy use by minimizing heat energy release in the heating return, and allows for efficient recovery of thermal energy, thereby reducing energy costs and enhancing the performance of heat pumps.
Implementation Method 1
decentralized preheating of the drinking water in a water-water heat exchanger with the heating water
Implementation Method 2
the heating water giving off thermal energy
Implementation Method 3
heating the preheated drinking water in an electric post-heater to a domestic hot water temperature
Implementation Method 4
routing warm waste water to be discharged through the water-water heat exchanger in order to recover thermal energy from the warm waste water
Data Source
Figure 1~1'
Figure 2
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AI summary
A method and a building technology system are proposed which very efficiently provide domestic hot water for apartments, offices, shops and building units. The invention is based on a two-stage heating for the drinking water, with two complementary heating stages of different principles being provided, namely one by means of a water-water heat exchanger and one by means of an electric after-heater.