Network Hydraulics
Pressurization, pressure profiles, operating modes and control
Network hydraulics describes how mass flows, pressures and temperatures interact within a heat network. Stable pressurization, an admissible pressure profile and coordinated control are prerequisites for supplying every consumer – including the hydraulically least favourable point. This topic area covers pressurization, pressure profiles, operating modes and control concepts.
6 articles in this category
Meeting Operating Pressure Limits in Heat Networks
What operating pressure, rest pressure, MOP, MIP and the nominal pressure rating mean, why gauge pressure is the working convention, and how the minimum pressure follows from the saturation pressure plus 1.5 bar
Network Operating Modes
Network operating modes in district heating networks: sliding, constant, and sliding-constant operation. Operating principles, advantages and disadvantages compared.
Pressurization and Expansion
Pressurization systems in thermal networks: open and closed systems, pre-charge pressure from the static height, expansion volume and make-up water
Pressure Profile and Pressure Diagram
The pressure diagram of a heat network: static pressure, rest pressure and pressure loss, the index point and the minimum differential pressure of 0.5 to 1.0 bar required there
Network Control
Control concepts for thermal networks: differential pressure control, index point and control with multiple feed-in points
Terrain Elevation and Topography in Network Planning
How terrain elevation enters the pressure balance of thermal networks: DTM versus DSM, data sources, vertical datum and the vertical accuracy actually required
Overview: Network Hydraulics
Network hydraulics deals with the pressure conditions in a heat network: how high the static pressure must be, how pressure develops along supply and return, and how it is ensured that every consumer receives the required differential pressure. These questions arise when planning new networks as well as when extending networks or connecting additional generators.
Pressurization fixes the pressure maintenance point, absorbs temperature-related volume changes and prevents evaporation and cavitation. The pressure diagram shows the pressure profile along the route and indicates whether permissible maximum pressures are respected and sufficient differential pressure is available at the index point, taking terrain heights and pressure losses into account.
The articles on operating modes and network control address operation: sliding, sliding-constant or constant supply temperature, the choice of the control variable, and the interplay of pumps, valves and transfer stations. The fundamentals of pressure loss calculation are covered under network design; the time-dependent coupling of hydraulics and heat transport is treated under heat network simulation.