District Heating System Modernized Using AFT Fathom
AFT Fathom™ Case Study
Energoprojekt Katowice | Hot Water System for HVAC | Commercial Building
“The possibility to perform scenario analyses…and use of
[the] GSC module allowed me to complete all tasks and save a lot of
time. Saving time for the engineer mean[s] saving the money for the
company.”
– Adam Klepacki, Energoprojekt Engineer
PROBLEM
- Project to modernize a district heating system
- Required to operate with various heat loading cases in both winter and summer conditions
ANALYSIS
- AFT Fathom was used to model the hydraulics and heat transfer
- Goal Seek & Control (GSC) module helped with pump sizing to meet specified flow rates and heat duties
SOLUTION
- New pumps were sized to meet all the various demands through changing seasons
- Future changes can be easily implemented because a standard model now exists
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Problem Explained
Energoprojekt Katowice was responsible for basic engineering in a project of modernizing a district heating system in Poland. AFT Fathom was used to model the heating water system for many heat loading and unloading cases in the winter time and summer time.
Energoprojekt’s engineer, Adam Klepacki, used the Scenario Manager to effectively model various ambient temperature conditions to determine the required pump head rise values to meet specific flow and heating demands. Klepacki used the Goal Seek and Control (GSC) module extensively to vary the pump head rise values to achieve specific flow rates.
Tools & Analysis
The heat exchanger sections were used in combination with flow control valve bypass loops to control the district water heating. In order to control the temperature of the system fluid flowing into the “heat accumulator” which was used to buffer heat production, a recycle stream at a particular temperature was mixed together with a flow stream at a different temperature. The system fluid mixture temperature was controlled with the use of a flow control valve in the recycle stream. The model also accounted for heat input to the system fluid from the pumps through the use of the “heat addition to fluid” feature in the pump specification windows.
Klepacki used the “Fill as Quadratic” feature to generate resistance curves to model the pressure losses for valves, screens, and heat exchangers. To keep the model from becoming overly complex, various fittings and losses such as bends, valves, and screens were included in the pipelines themselves as additional pipe fittings and losses.
Solutions & Benefits
In commenting on the benefits of modeling this system with AFT Fathom, Klepacki said; “It would be very difficult and time consuming to calculate such [a] complicated system without specialized software. The possibility to perform scenario analyses (for different operation regimes) and [the] use of GSC module (calculation of main pumps head rise in relation to required water flow) allowed me to complete all tasks and save a lot of time. Saving time for the engineer mean[s] saving the money for the company. Another very important thing is when we need to introduce changes. There is no problem with such a model because every change in the design data can be easily implemented and new results are available in a few seconds.”
Klepacki continued; “All of this means benefits for the design process but it is very important to say that a very detailed analysis brings benefits also for the investor who knows that selected pumps exactly match his needs and the system will operate without unnecessary losses.”
Energoprojekt District Heating System Model
Heating System Heat Accumulator