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Low-Lift Chiller, Chilled Slab, and Model-Predictive Controls

Principal Investigator:
Dr. Peter Armstrong, Associate Professor in Mechanical Engineering, Masdar Institute


Brief:

The project aims to develop guidelines for identifying building thermal response from measured data, implement a supervisory control for optimal operation of a low-lift radiant cooling with pre-cooling control system and demonstrate system’s energy savings compared to conventional split-unit systems at a medium scale building. First principles models of vapor compression cycle were developed to predict the system COP within ±20% while operating as a chiller or a DX fan coil. The models were validated with the data obtained from MIT test stand (Gayeski, 2010) and MI test stand built as part of the thesis. The models were also compared with the heat pump models of (Zakula, 2011) and equations for controlling compressor and condenser fan speeds based on the optimization results of (Zakula, 2011) were also presented.


Low lift MFS demo is final deliverable of MI-MIT collaboration:

  • 8-ton chiller barrel for precooling the floor slab (sensible loads)
  • 8-ton multi-split with 3 DX indoor units, one in workshop, 2 in lab


Latent loads addressed by existing DOAS system with:

  • Demand controlled ventilation with variable supply air dew point


Variable-speed mini-split DX dehumidification coil

  • Addition of runaround heat exchanger


Impact on building

  • Interface to BMS (demand response; precooling)
  • Reversible modification of DOAS
  • Multi-split line-set will enter lab side of shop through wall panel
  • Mini-split line set will enter from roof through exhaust curb
  • Chiller barrel will connect to floor coils (existing isolation valves)