Performance analysis of pulsed flow control method for radiant slab system

Performance analysis of pulsed flow control method for radiant slab system

TitlePerformance analysis of pulsed flow control method for radiant slab system
Publication TypeJournal Article
Year of Publication2018
AuthorsHaida Tang, Paul Raftery, Xiaohua Liu, Stefano Schiavon, Jonathan Woolley, Fred S Bauman
JournalBuilding and Environment
Volume127
107
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.

DOI10.1016/j.buildenv.2017.11.004