Simplifications for hydronic system models in modelica

Journal Article · 11 January 2018 · Journal of Building Performance Simulation

DOI: https://doi.org/10.1080/19401493.2017.1421263 · OSTI ID:1437004

Jorissen, F.  ^[1]; Wetter, M. ^[2]; Helsen, L.  ^[1]

---

1. Univ. of Leuven (Belgium); EnergyVille, Genk (Belgium)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Building systems and their heating, ventilation and air conditioning flow networks, are becoming increasingly complex. Some building energy simulation tools simulate these flow networks using pressure drop equations. These flow network models typically generate coupled algebraic nonlinear systems of equations, which become increasingly more difficult to solve as their sizes increase. This leads to longer computation times and can cause the solver to fail. These problems also arise when using the equation-based modelling language Modelica and Annex 60-based libraries. This may limit the applicability of the library to relatively small problems unless problems are restructured. This paper discusses two algebraic loop types and presents an approach that decouples algebraic loops into smaller parts, or removes them completely. The approach is applied to a case study model where an algebraic loop of 86 iteration variables is decoupled into smaller parts with a maximum of five iteration variables.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1437004
• Journal Information: Journal of Building Performance Simulation, Journal Name: Journal of Building Performance Simulation Journal Issue: none Vol. none; ISSN 1940-1493
• Publisher: Taylor & FrancisCopyright Statement
• Country of Publication: United States
• Language: English