Title: A fast and accurate modeling approach for water and steam thermodynamics with practical applications in district heating system simulation

Abstract

In U.S. district heating (DH) systems, steam is the most common heat transport medium. Industry demand for new advanced modeling capabilities of complete steam DH systems is increasing; however, the existing models for water/steam thermodynamics are too slow for large system simulations because of computationally expensive algebraic loops that require the solution to nonlinear systems of equations. For practical applications, this work presents a novel split-medium approach that implements numerically efficient liquid water models alongside various water/steam models, breaking costly algebraic loops by decoupling mass and energy balance equations. New component models for steam DH systems are also presented. We implemented the models in the equation based Modelica language and evaluated accuracy and computing speed across multiple scales: from fundamental thermodynamic properties to complete districts featuring 10 to 200 buildings. Compared to district models with the IF97 water/steam model and equipment models from the Modelica Standard Library, the new implementation improves the scaling rate for large districts from cubic to quadratic with negligible compromise to accuracy. Additionally, for an annual simulation with 180 buildings, this translates to a computing time reduction from 33 to 1-1.5 h. These results are critically important for industry practitioners to simulate steam DH systems atmore » large scales.« less

Authors:

Hinkelman, Kathryn  ^[1];

• Search DOE PAGES for author "Hinkelman, Kathryn"
• Search DOE PAGES for ORCID "0000-0002-8297-6036"

Anbarasu, Saranya ^[2]; Wetter, Michael  ^[3];

• Search DOE PAGES for author "Wetter, Michael"
• Search DOE PAGES for ORCID "0000-0002-7043-0802"

Gautier, Antoine ^[3]; Zuo, Wangda  ^[4]

• Search DOE PAGES for author "Zuo, Wangda"
• Search DOE PAGES for ORCID "0000-0003-2102-5592"

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+ Show Author Affiliations

1. Pennsylvania State Univ., University Park, PA (United States)
2. Univ. of Colorado, Boulder, CO (United States)
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
4. Pennsylvania State Univ., University Park, PA (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)

Publication Date:

Tue May 17 00:00:00 EDT 2022

Research Org.:

National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Building Technologies Office; USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Advanced Manufacturing Office

OSTI Identifier:

1889680

Alternate Identifier(s):

OSTI ID: 1869723; OSTI ID: 1892186

Report Number(s):

NREL/JA-5500-84103
Journal ID: ISSN 0360-5442; MainId:84876;UUID:7c8df227-68b0-4ab2-ac24-ea5924746a4e;MainAdminID:67587

Grant/Contract Number:  

AC36-08GO28308; SC0014664; EE0009139; AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Energy

Additional Journal Information:

Journal Volume: 254; Journal Issue: Part A; Journal ID: ISSN 0360-5442

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 97 MATHEMATICS AND COMPUTING; 42 ENGINEERING; computing speed; district heating; modelica; modeling; simulation; steam