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Performance analysis of pulsed flow control method for radiant slab system

  • Author(s): Tang, Haida
  • Raftery, Paul
  • Liu, Xiaohua
  • Schiavon, Stefano
  • Woolley, Jonathan
  • Bauman, Fred S
  • et al.

Published Web Location

https://doi.org/10.1016/j.buildenv.2017.11.004
The data associated with this publication are in the supplemental files.
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International Public License
Abstract

We present a novel pulsed flow control method (PFM) using a two-position valve to regulate the capacity of radiant slab systems. Under PFM, the on-time duration of the valve is short (compared to all prior work, e.g. 4-minute), and fixed, while the off-time varies. We present a novel, open-source, finite difference model that assesses three-dimensional transient slab heat transfer, accounting for the transient heat storage of the pipe fluid. Sensitivity analysis results indicate the dominant factors influencing energy performance of the PFM are: on-time duration; pipe diameter; and spacing. We experimentally validated both the new control strategy and model in full-scale laboratory experiments. Compared with previous intermittent control strategies (with on-time durations over 30 min), at 50% part load the PFM reduces 27% required water flow rate and increases supply to return water temperature differential. Compared with the variable temperature control method, at 50% part load the PFM reduces 24% required water flow rate. The energy performance of PFM is comparable to that of a conventional variable flow rate control. However, it has more accurate capacity control, achieves a more uniform surface temperature distribution, and reduces initial investment by substituting two-position for modulating valves, thus showing promise for engineering applications.

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