Method for optimizing a district heating network
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Solution Overview
Problem
District heating systems face challenges with centralized heat generation leading to high pressure and temperature requirements, limiting network size and expansion, and seasonal inefficiencies due to idle plants during summer months, while existing storage solutions like water tanks have limited capacity and borehole storage suffer from significant heat losses.
Innovation Solution
Implementing distributed borehole thermal energy storage (BTES) with strategic locations and a controller unit to manage heat distribution and storage, using heat pumps to regulate temperature and pressure, allowing decentralized heat sources and flexible temperature management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If centralized heat generation is used, then heat supply is sufficient, but network expansion is limited due to high pressure and temperature requirements
Solution Approach 1:
The patent divides the centralized heat generation system into multiple distributed heat storage units (borehole thermal energy storages) positioned at different locations in the network. Each unit can independently store and release heat, allowing the system to expand to peripheral areas without requiring increased central pressure and temperature. The segmentation enables modular expansion while maintaining reliable heat supply throughout the extended network.
2Duration of action of moving object
If heat is stored in water tanks, then short-term storage is achieved, but storage capacity is limited
Solution Approach 1:
The patent transitions from above-ground water tank storage to underground borehole thermal energy storage, utilizing the vertical dimension of the ground. Multiple nested rings of boreholes are drilled at different depths and radii, creating a three-dimensional storage field. This dimensional change dramatically increases storage capacity while providing long-term seasonal storage capability beyond the short-term limitations of water tanks.
3Quantity of substance
If ground-based storage in boreholes is used, then storage capacity is increased, but heat losses increase exponentially with temperature
Solution Approach 1:
The patent implements a nested configuration where multiple rings of boreholes are positioned concentrically at different radii from a central heat pump location. The outer rings store heat at lower temperatures while inner rings maintain higher temperatures, creating a thermal gradient that minimizes heat loss to the surrounding ground. This nested arrangement optimizes both storage capacity and thermal efficiency by matching storage zones to temperature requirements.
4Adaptability or versatility
If pressure and temperature are increased to expand network reach, then peripheral areas can be served, but storage efficiency decreases
Solution Approach 1:
The patent implements local quality by positioning distributed heat storage units at specific strategic locations throughout the network, including peripheral areas. Each location has its own borehole thermal energy storage system tailored to local demand patterns and distance from the central heat source. This allows peripheral areas to be served without requiring increased central pressure and temperature, as local storage units provide thermal energy directly at the point of use, maintaining storage efficiency while expanding network coverage.
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
Enables efficient heat distribution and storage, optimizing network flexibility and reducing energy losses, enabling year-round operation and cost-effective management of thermal energy.
Implementation Method 1
heat pumps will be used to raise the heat in a central location of the field of boreholes
Implementation Method 2
Borehole Thermal Energy Storage, hereby abbreviated 'BTES'
Implementation Method 3
a field of outwards diminishing temperature (Borehole Thermal Energy Storage, hereby abbreviated 'BTES')
Implementation Method 4
a controller unit will be assigned to monitor the temperature in the outgoing pipes and returning pipes of the district heating network as well as to monitor the temperatures of the different rings of the borehole field
Data Source
AI summary
The invention relates to a method for optimizing a district heating network (1) comprising outgoing supply pipes and incoming return pipes, wherein a heat carrying fluid is circulated to be utilized for residential and commercial heating requirements. For storing excess thermal energy available at the district heating network. the method involves the steps of implementing more than one ground-based borehole thermal energy storage (4) as distributed heat storages at different locations of or along the district heating network (1). Each heat storage (4) is adapted to receive thermal energy from various forms of heat sources. which heat sources may be found at different locations of or along the district heating network (1) such, that the heat sources and the heat storages forming nodes in the district heating network (1). Excess thermal energy available to one node of the district heating network (1) is used to charge a borehole thermal energy storage (4) at one or several nodes, and thermal energy available from the borehole thermal energy storages (4) is at disposal to be used to heat the heat carrying fluid circulated in the supply pipes of the district heating network.