Buildings.DHC.UsersGuide

Information

Overview

The package Buildings.DHC consists of models for district heating and cooling (DHC) systems. The package contains models at the component, sub-system, and system level, which can be used as templates or for generating custom system models. Generally, the model structures are capable of representing any generation of DHC (1st-5th), though template models are not specifically available for all system types and combinations of technology. Note also that some components typically seen in district networks have been implemented elsewhere in the library (e.g. geothermal storage).

The structure of the package is such that it decomposes a DHC into four primary sub-systems each with their own sub-packages as described in the table below: Energy Transfer Stations (ETS), Loads, Networks, and Plants. In addition to these sub-packages, the sub-package Buildings.DHC.Examples contains system models which may be used as examples or templates.

Sub-Package Description
Buildings.DHC.ETS Connection point between a building and district network which contains physical components such as heat exchangers, heat pumps, pipes, valves, sensors, and pumps, as well as control logic based on flow rate, temperature, and/or pressure measurements.
Buildings.DHC.Loads Timeseries or physics-based representation of space heating and cooling and domestic hot water loads in buildings, and connected to an ETS.
Buildings.DHC.Networks Distribution system between buildings and plants which contains distribution pipes and service lines to the energy transfer stations.
Buildings.DHC.Plants Sources of cooling or heating for the DHC such as boilers, chillers, heat pumps, waste heat, tank storage, and geothermal storage.

The figure below further illustrates the abstract relationship between the sub-systems and offers concrete example systems which can be modeled with concrete implementation of the abstractions.

image

Further sub-packages divide the application of each model based on the terms in the table below:

Further Sub-Package Description
Combined Water-based heating and cooling
Cooling Water-based cooling only
Heating Water-based heating only
HotWater Domestic hot water
Steam Steam-based heating only

Content Summary

This section provides a summary of the models available in the package to help a user navigate. However, refer to the specific documentation of the model and subpackages for further modeling and implementation details.

Sub-Package Name Model Name Model Description
Buildings.DHC.ETS
Combined ChillerBorefield ETS with heat recovery chiller and optional borefield.
HeatPumpHeatExchanger ETS with heat pump for heating, heat pump for domestic hot water, and compressor-less cooling by heat exchanger.
HeatPumpHeatExchangerDHWTank ETS with heat pump for heating, heat pump with storage tank and heat exchanger for domestic hot water, and compressor-less cooling by heat exchanger.
Cooling Direct ETS with direct connection and district return water temperature control. In-building pumping not modeled.
Indirect ETS with indirect connection with heat exchanger and building supply water temperature control. In-building pumping not modeled.
Heating Direct ETS with direct connection and district return water temperature control. In-building pumping not modeled.
Indirect ETS with indirect connection with heat exchanger and building supply water temperature control. In-building pumping not modeled.
Buildings.DHC.Loads
Combined BuildingTimeSeriesWithETS Building with loads provided as time series, connected to an ETS with heat pump for space heating, heat pump for domestic hot water, and a heat exchanger for cooling water.
BuildingTimeSeriesWithETSWithDHWTank Building with loads provided as time series, connected to an ETS with heat pump for space heating, heat pump with storage tank and heat exchanger for domestic hot water, and a heat exchanger for cooling water.
Cooling BuildingTimeSeriesWithETS Building with loads provided as time series, connected to an ETS with direct connection for chilled water supply to the building.
Heating BuildingTimeSeriesWithETS Building with loads provided as time series, connected to an ETS with direct connection for heating water supply to the building.
HotWater DirectHeatExchangerWithElectricHeat A model for generating hot water using a district heat exchanger and supplemental electric resistance.
StorageTankWithExternalHeatExchanger A model of a storage tank with external heat exchanger to produce hot water.
ThermostaticMixingValve A model for a thermostatic mixing valve.
Steam BuildingTimeSeriesAtETS Steam heating building interconnection with the district piping only and the load at the ETS provided as a time series.
Buildings.DHC.Networks
Distribution1PipePlugFlow_v 1-Pipe distribution network with fluid heat transfer modeled in the main lines between ETS determined by external model (e.g. ground) and flow friction by nominal velocity.
Distribution1Pipe_R 1-Pipe distribution network with flow friction modeled in the main lines between ETS determined by pressure drop per length.
Distribution2PipePlugFlow_v 2-Pipe distribution network with fluid heat transfer modeled in the main lines between ETS determined by external model (e.g. ground) and flow friction by nominal velocity.
Distribution2Pipe_R 2-Pipe distribution network with flow friction modeled in the main lines between ETS determined by pressure drop per length.
Steam DistributionCondensatePipe 2-Pipe distribution network with steam supply and condensate return using a fixed resistance pipe model for condensate returns.
Buildings.DHC.Plants
Combined AllElectricCWStorage All-electric chilled water and heating water production plant with heat recovery chillers and condenser water storage.
Cooling ElectricChillerParallel Chilled water production plant with parallel chillers and parallel cooling towers.
StoragePlant Chilled water storage tank system which can be charged by local chiller or remotely from district.
Heating SewageHeatRecovery Heating water production plant using sewage heat recovery.
Steam SingleBoiler Steam plant with a single boiler that discharges saturated steam.
Buildings.DHC.Examples
Combined SeriesConstantFlow Example of ambient network, so-called Reservoir Network, with constant district water mass flow rate.
SeriesVariableFlow Example of ambient network, so-called Reservoir Network, with variable district water mass flow rate.
SeriesVariableFlowAgentControl Example of ambient network, so-called Reservoir Network, with variable district water mass flow rate with updated agent controller.
Cooling ElectricChillersDirectETS Example model for district cooling system with an electric chiller plant and a direct controlled ETS at each building.
Steam SingleBoiler Example model for a steam district heating system with a central plant boiler producing steam that is distributed to each building.

Extends from Modelica.Icons.Information (Icon for general information packages).