District heat transfer device for a building and district heating system for supplying buildings with thermal energy
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Solution Overview
Problem
Current district heating systems face inefficiencies due to high operating temperatures, leading to high costs and limited economic viability, especially in large distances and small heat demand scenarios, as they struggle to utilize waste heat effectively and efficiently supply domestic hot water at required temperatures.
Innovation Solution
A district heating system comprising a refining station for waste heat, a one-pipe arrangement for long-distance heat transfer, and a hybrid heating and domestic hot water station that uses heat pumps and peak load boilers to achieve efficient temperature conversion and distribution, reducing energy losses and costs while stabilizing the power grid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperatures (90-120°C) are used in district heating flow, then transport capacity in pipelines is increased, but system costs and energy losses increase significantly
Solution Approach 1:
The patent fundamentally changes the temperature parameter from conventional high temperatures (90-120°C) to low temperatures (20-30°C) by utilizing waste heat directly. This parameter change resolves the contradiction by achieving adequate transport capacity through high flow rates and optimized pipe insulation rather than relying on high temperature differentials, thereby significantly reducing heat losses while maintaining system productivity
Solution Approach 2:
The patent replaces the conventional thermal-mechanical system (high temperature differential driving heat transfer) with a fluid dynamics-based system (high flow rate through well-insulated pipes). Instead of relying on large temperature spreads to drive heat transport, the system uses pumped circulation of large volumes of moderately warm water, substituting thermal efficiency for hydraulic capacity
2Length of stationary object
If high flow temperatures (90-120°C) are maintained, then heat transport over long distances is enabled, but pipe insulation requirements and system complexity increase
Solution Approach 1:
By changing the operating temperature parameter to low temperatures (20-30°C), the patent reduces the absolute temperature difference with the environment. This allows for simpler insulation requirements compared to high-temperature systems, as the temperature gradient driving heat loss to the surroundings is much smaller, enabling long-distance distribution with more manageable insulation standards
3Loss of energy
If return temperature is reduced to utilize waste heat, then energy efficiency improves, but the temperature spread for heat pumps increases reducing their effectiveness
Solution Approach 1:
The patent extracts waste heat directly from industrial sources at low temperatures (20-30°C) and transports it through dedicated low-temperature district heating pipelines to residential areas. This extraction approach bypasses the need for heat pumps by creating a separate low-temperature distribution network that delivers waste heat directly to low-temperature heating systems in buildings, eliminating the temperature lift problem that reduces heat pump effectiveness
Solution Approach 2:
The patent segments the heating system into distinct temperature zones: a low-temperature waste heat distribution network (20-30°C) for heating and a separate high-temperature system (60-70°C) for domestic hot water. This segmentation allows waste heat to be utilized directly without requiring temperature elevation, while domestic hot water needs are met through a different subsystem, resolving the contradiction between waste heat utilization and heat pump efficiency
4Reliability
If domestic hot water temperatures of 60-70°C are provided for hygienic reasons, then legionella prevention is achieved, but the return temperature from hot water systems increases reducing overall system efficiency
Solution Approach 1:
The patent segments the thermal system into two independent temperature levels: low-temperature heating circuits (20-30°C supply, 10-20°C return) for space heating, and a separate high-temperature domestic hot water system (60-70°C) for hygienic needs. This segmentation allows the hot water system to operate independently at higher temperatures for legionella prevention without adversely affecting the return temperature of the low-temperature heating system, as the two systems are thermally decoupled
Solution Approach 2:
The patent introduces a thermal store (buffer tank) as an intermediary between the low-temperature heating system and the high-temperature domestic hot water system. The thermal store allows heat to be transferred from the low-temperature heating circuit to heat up domestic hot water on demand, enabling the hot water system to reach hygienic temperatures (60-70°C) without directly drawing hot water from the heating return, thus maintaining low return temperatures in the heating system while achieving hygienic safety
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 system achieves increased energy efficiency, reduced capital costs, and extended heat distribution radius, enabling the utilization of waste heat and providing hygienic hot water without excessive energy expenditure, while stabilizing the power grid and reducing carbon emissions.
Implementation Method 1
The temperature of the district heating medium is increased in a heat pump from the low temperature of the waste heat, i.e. 20-30° C., to a higher temperature
Implementation Method 2
In the heat exchanger, the district heating medium is cooled down again to low temperature, i.e. 10-20° C.
Data Source
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AI summary
The device has a heat exchanger transmitting heat energy from a long-distance heating pipeline to a heating circuit for heating fluid. A memory device, which is in communication with the heating circuit, stores different temperature levels of the heating fluid in layers. A heat pump is arranged within the memory device for increase of temperature gradient between heating fluid layers. The memory device includes a first fluid container for storing heating fluid in first temperature level, which is different from the temperature level of the heating fluid stored in a second fluid container. An independent claim is also included for a district heating system.