1.2 Energy conservation in hydronic systems through the
use of drag-reducing additives.
This is applied work drawing heavily on the more fundamental work
described in section 1.1. One proposed concept is to use drag-reducing
surfactant solutions as energy transmission fluids in HVAC systems.
We have started by conducting an extensive theoretical feasibility
study to determine the potential of the technique, and especially
so for hydronic cooling systems in buildings, an application of
great interest. This study showed that even for these systems
the proposed approach would result in very large energy savings
(up to about 50% of the energy used by pumps). Other types of
applications such as fluid transport or industrial processes are
also promising candidates for the use of our additives.
The next step in the process was to conduct extensive
experimental work in the laboratory to generate a good understanding
of the fundamental behavior of these fluids and their effect on
system components (see section 1.1). Finally, we have undertaken
a major field test in an operating hydronic space cooling system
in a large building on campus. This complex system was thoroughly
analyzed, tested, and fully instrumented with customized sensors,
both locally and globally. In the first phase of the field test,
extensive measurements were completed to determine the maximum
pumping power savings possible, i.e. without any heat transfer
control attempted. We obtained approximately 30% pumping power
savings, very close to the level calculated using the predicting
techniques we developed. The system ran well with the additives,
and much information was gathered on numerous component such as
pumps, coils, the evaporator, pipes, fittings, etc. In the second
part of the field test we addressed the issue of the decreased
heat exchanger capacity that was quantified in the first phase
of the test. We used our new non-ionic additive to see if we could
implement our heat transfer reduction control techniques in the
field. These proved to work very well, allowing us to restore
the nominal chiller performance and to generate true power savings
for the system of the order of 15%. Further optimization of the
additives is presently underway that will allow us to achieve
higher savings still. All in all this field test work was judged
to have been very successful.
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