A systematic review of treatments and fixes for low delta-T syndrome in cooling systems

Low delta-T syndrome is known to decrease the energy efficiency of chilled water systems and jeopardize human thermal comfort. Many studies have addressed low delta-T syndrome, suggesting possible measures to solve or mitigate its symptoms. However, while numerous measures have been proposed, a connection to the fundamental causes and the potential side effects that could cause low delta-T syndrome is lacking. This systematic literature review aims to identify measures to address low delta-T syndrome in various parts of chilled water systems and classify the 25 identified measures for the four subclasses of low delta-T syndrome as treatments or fixes. For the subclass of low delta-T syndrome without increased flow, fifteen measures were classified as a treatment; five were classified as a fix and five could not be classified. For the three subclasses of low delta-T syndrome with increased flow, 11 were classified as fixes, nine as a treatment and five could not be classified. The main reason four of the six measures could not be classified is due the disputed cause of laminar or transitional flow condition inside the cooling coil tubes. Despite the reported positive effects in existing chilled water systems, many measures are considered fixes because they do not address the fundamental causes of low delta-T syndrome but merely mitigate its signs and symptoms.