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Reducing Airflow Energy Use in Multiple Zone VAV Systems

Tukur, Ahmed Gidado
http://rave.ohiolink.edu/etdc/view?acc_num=dayton1467872641

Abstract Details

2016, Doctor of Philosophy (Ph.D.), University of Dayton, Engineering.
Variable Air Volume (VAV) systems are the most popular HVAC systems in commercial buildings. VAV systems are designed to deliver airflows at design conditions which only occur for a few hours in a year. Minimizing energy use in VAV systems requires reducing the amount of airflow delivered through the system at part load conditions. Air Handling Unit (AHU) fans are the major drivers of airflow in VAV systems and installing a Variable Frequency Drive (VFD) is the most common method of regulating airflow in VAV systems. A VFD drive does not necessarily save energy without use of an appropriate control strategy. Static pressure reset (SPR) is considered to be the most energy efficient control strategy for AHU fans with VFDs installed. The implementation of SPR however has many challenges; for example, rogue zones—zones which have faulty sensors or failed controls and actuators, system dynamics like hunting and system diversity. By investigating the parameters associated with the implementation of SPR in VAV systems, a new, improved, more stable SPR algorithm was developed and validated. This approach was further improved using Fault Detection and Diagnostics (FDD) to eliminate rogue zones. Additionally, a CO2-Demand Control Ventilation (DCV) based minimum airflow control was used to further reduce ventilation airflow and save more energy from SPR. Energy savings ranging from 25% to 51% were recorded in actual buildings with the new SPR algorithm. Finally, a methodology that utilizes historical VAV data was developed to estimate the potential savings that could be realized using SPR. The approach employed first determines an effective system loss coefficient as a function of mean damper position using the historical duct static pressure, VAV damper positions and airflows. Additionally, the historical data is used to identify the maximum mean duct damper position realizable as a result of insuring a sufficient number of VAVs are fully open at any time. Savings are estimated by shifting the damper distribution mean at each time to this maximum value and reducing the static pressure to achieve the same overall system airflow rate. The methodology was tested on three different buildings with varying system characteristics. Savings estimates correlated well to the savings actually realized from SPR. This result has significant implications for energy service providers, who could use the predictions to guarantee savings from SPR.
Kevin Hallinan (Committee Chair)
Kelly Kissock (Committee Co-Chair)
Andrew Chiasson (Committee Member)
Zhenhua Jiang (Committee Member)
93 p.
Energy; Engineering; Mechanical Engineering
Building Energy Efficiency; Advanced Building Controls; VAV Systems Control; HVAC Controls; Static Pressure Reset; Critical Zone Control; Commercial Buildings HVAC; Multiple Zone VAV; VAV Airflow Reduction; Energy Efficient HVAC;

Recommended Citations

Citations

  • Tukur, A. G. (2016). Reducing Airflow Energy Use in Multiple Zone VAV Systems [Doctoral dissertation, University of Dayton]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1467872641

    APA Style (7th edition)

  • Tukur, Ahmed. Reducing Airflow Energy Use in Multiple Zone VAV Systems. 2016. University of Dayton, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=dayton1467872641.

    MLA Style (8th edition)

  • Tukur, Ahmed. "Reducing Airflow Energy Use in Multiple Zone VAV Systems." Doctoral dissertation, University of Dayton, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1467872641

    Chicago Manual of Style (17th edition)

dayton1467872641
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© 2016, all rights reserved.
This open access ETD is published by University of Dayton and OhioLINK.
Release 3.2.12