aqueous fluid, with operating supply
and return temperatures of 30 F and
54 F. The TES is designed to discharge
at flow rates of up to 25,500 gpm or
25,000 tons at the LTF delta T of 24 F,
enough to fully discharge the TES in
under 5 hours.
This particular TES system provides
the following benefits:
• The availability of a low supply
temperature ( 30 F), used to produce
low-temperature air for distribution
in miles of air ducts within the
convention complex, reducing the
size and cost of ducts and fans.
• A larger-than-normal TES supply-to-return temperature difference ( 24
F), reducing the volume versus that
required for conventional chilled-water TES and achieving a tank
footprint of only 0.5 sq ft/ton, less
than that of conventional (non-TES)
chiller plants.
• Reduction in peak electric demand of
approximately 20 MW, with associated
reductions in operating demand and
energy costs.
• A fully installed (1994) capital cost
for the tank (including its LTF) that
was under $40/ton-hr of TES capacity
and under $200/ton of discharge
capacity – far less than the cost of
equivalent conventional (non-TES)
chiller plant capacity.
• Avoidance of the need for ongoing
water treatment, as the chemicals
used in the aqueous LTF provide
essentially permanent water treatment for control of both corrosion
and microbiological activity.
• Extremely low maintenance requirements and a continuous successful
operating history (of 18 years and
counting), not unlike many other
TES installations dating to the 1990s
and older. TES equipment is generally quite simple and static, with a
longer expected operating life than
that of mechanical chiller plant
equipment.
Finally, yet another powerful testimony to the value of TES for district
energy systems is the wide incidence of
satisfied system developers, owners
and operators who have installed multiple TES systems at one or more of
Table 3. Examples of District Cooling Systems With Multiple TES Installations.
District Energy System
Developer/Owner/Operator
Total TES
(ton-hr)
TES Type Number
of TES
Installations
University of Arizona-Tucson
Qatar Cool
3M Corp.
Ford Motor Corp.
U.S. Veterans Administration
24,000
46,200
51,200
62,000
64,000
District Energy St. Paul
University of Texas System
Texas Instruments
Tabreed, Abu Dhabi, UAE
State Farm Insurance
Toyota (U.S. and Canada)
General Motors
University of California System
Trigen (Some systems later sold)
65,400
70,000
102,030
108,000
125,600
180,000
205,000
254,000
303,000
California State University System
Northwind (U.S. and Canada)
Saudi Electricity Company
305,000
434,900
Ice
Chilled water
Chilled water
Chilled water
Chilled water,
Low-temperature fluid
Chilled water
Chilled water
Chilled water
Chilled water
Chilled water
Chilled water
Chilled water
Chilled water
Chilled water,
Low-temperature fluid
Chilled water
Ice
Chilled water, Ice
Number
of District
Cooling
Networks
2 1
2 2
3 3
5 4
3
2
3
3
7
5
5
5
8
3
1
3
3
5
4
3
4
7
3
17
9
6
3
14
6
3
Source: The Cool Solutions Company.
Peter B. Myers Peter B. Myers
Courtesy Chicago Bridge & Iron Co.
