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Thermal storage systems (TESs) for trucks are relatively new. A TES consists of a phase-
change material that stores heating or cooling energy that is transferred from the vehicle engine
or air-conditioning while the vehicle is operating (PCG 1995). One company, SHAPE Energy
Resources (Store Heat and Produce Energy, Inc.), offered systems with thermal tank capacities
from 16 to 35 gal, which allow heat storage capacities of up to about 23,000 Btu.
or air-conditioning while the vehicle is operating (PCG 1995). One company, SHAPE Energy
Resources (Store Heat and Produce Energy, Inc.), offered systems with thermal tank capacities
from 16 to 35 gal, which allow heat storage capacities of up to about 23,000 Btu.
SHAPE Energy Resources is now out of business. With TESs, heating and cooling, but no
electrical power, can be supplied to the sleeper compartment (only) for up to 8 h while the cab is
allowed to cool off or heat up. A small amount of electrical power is required. TESs are large
compared with the direct-fired heaters (which only supply heat), but they are similar in size to
APUs. These units have been tested by several large trucking companies, including Schneider
and Dart Transit, and have been evaluated by Peterbilt and others as factory options
(SHAPE 1997). The effectiveness of TESs depends on the duty cycle of the truck, which could
be a disadvantage under certain conditions (for example, if the air conditioner was not used
during the day, the TES could not cool the sleeper overnight). Limited cost and performance data
are available for this technology. The Thermocooler, a variant offered by Webasto (see Figure 5),
allowed to cool off or heat up. A small amount of electrical power is required. TESs are large
compared with the direct-fired heaters (which only supply heat), but they are similar in size to
APUs. These units have been tested by several large trucking companies, including Schneider
and Dart Transit, and have been evaluated by Peterbilt and others as factory options
(SHAPE 1997). The effectiveness of TESs depends on the duty cycle of the truck, which could
be a disadvantage under certain conditions (for example, if the air conditioner was not used
during the day, the TES could not cool the sleeper overnight). Limited cost and performance data
are available for this technology. The Thermocooler, a variant offered by Webasto (see Figure 5),
Figure 5 Webasto Thermocooler
®
, Auxiliary Climate Control System
(Reproduced with permission, Webasto Thermosystems, Inc., Lapeer,
Michigan)
Michigan)