Coupling fast fluid dynamics and multizone airflow models in Modelica Buildings library to simulate the dynamics of HVAC systems

Journal Article · Thu Jun 08 00:00:00 EDT 2017 · Building and Environment

DOI:https://doi.org/10.1016/j.buildenv.2017.06.013· OSTI ID:1787837

Tian, Wei ^[1]; Sevilla, Thomas Alonso ^[1]; Zuo, Wangda ^[1]; Sohn, Michael D. ^[2]

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1. Univ. of Miami, Coral Gables, FL (United States)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Multizone models are widely used in building airflow and energy performance simulations due to their fast computing speed. However, multizone models assume that the air in a room is well mixed, consequently limiting their application. In specific rooms where this assumption fails, the use of computational fluid dynamics (CFD) models may be an alternative option. Previous research has mainly focused on coupling CFD models and multizone models to study airflow in large spaces. While significant, most of these analyses did not consider the coupled simulation of the building airflow with the building’s Heating, Ventilation, and Air-Conditioning (HVAC) systems. This paper tries to fill the gap by integrating the models for HVAC systems with coupled multizone and CFD simulations for airflows, using the Modelica simulation platform. To improve the computational efficiency, we incorporated a simplified CFD model named fast fluid dynamics (FFD). We first introduce the data synchronization strategy and implementation in Modelica. Then, we verify the implementation using two case studies involving an isothermal and a non-isothermal flow by comparing model simulations to experiment data. Afterward, we study another three cases that are deemed more realistic. Furthermore, this is done by attaching a variable air volume (VAV) terminal box and a VAV system to previous flows to assess the capability of the models in studying the dynamic control of HVAC systems. Finally, we discuss further research needs on the coupled simulation using the models.

• Research Organization: Univ. of Colorado, Boulder, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Building Technologies Office
• Grant/Contract Number: EE0007688; AC02-05CH11231
• OSTI ID: 1787837
• Alternate ID(s): OSTI ID: 1495599
• Journal Information: Building and Environment, Vol. 122; ISSN 0360-1323
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
Fast fluid dynamics
Multizone airflow networks
Modelica
HVAC modeling