Note: Descriptions are shown in the official language in which they were submitted.
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ABSORPTION COOLING FOR AIRCRAFT TROLLEYS AND
COMPARTMENTS
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional Application
Serial
No. 61/712,368, filed October 11, 2012, titled "Absorption Cooling Used on
Galley's
Trolley Compartment," and U.S. Provisional Application Serial No. 61/712,370,
filed
October 11, 2012, titled "Absorption Cooling Used on Trolley Cooling," the
entire
contents of each of which are hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] Embodiments of the present invention relate generally to improved
cooling
systems and methods for use on aircraft trolleys and compartments.
BACKGROUND
[0003] Aircraft trolleys are used to chill and maintain the temperature
of food and
various other items that are to be served on-board an aircraft. The trolleys
are
generally chilled via an airflow from an air chiller or compressor that is
directed over
the items in the trolley. In many instances, the trolley has an opening in the
back that
can be aligned with a cool air blower that causes air to flow into the trolley
and
around the food and beverage items contained therein. This configuration can
make it
difficult to move and interchange the trolleys. Improvements to these cooling
systems
would be beneficial.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 shows a side cross-sectional view of a trolley cooling
system.
[0005] FIG. 2 shows a side cross-section view of an alternate trolley
cooling
system.
[0006] FIG. 3 shows a schematic of the trolley cooling systems of FIGS. 1
and 2.
[0007] FIG. 4 shows a top plan view of an alternate trolley cooling
system.
[0008] FIG. 5 shows a schematic of the trolley cooling system of FIG. 4.
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DETAILED DESCRIPTION
[0009] Absorption cooling uses a heat source to drive the cooling system.
For
example, an absorption refrigerator is a refrigerator that uses a heat source
(such as a
solar source, a kerosene-fueled flame, or waste heat from factories) to
provide the
energy needed to drive the cooling system. In the early part of the twentieth
century,
the vapor absorption cycle using water-ammonia systems was widely used, but
upon
development of the vapor compression cycle, it lost much of its use.
Absorption
cooling technology has not been used for air conditioning or chilling inside
aircraft.
[0010] The present inventors have determined that if an appropriate heat
source
could be provided, the use of absorption cooling on-board aircraft or other
vehicles
could be a viable alternative to the cooling that is provided by air chillers
or
compressors in order to recycle the heat and to reduce noise from the
traditional
cooling systems. Replacing an electric air chiller with an absorption cooler
can also
reduce electricity loads. Embodiments of the present invention thus provide
absorption cooling systems for trolleys and other containers in aircraft or
other vehicle
galleys. In a specific embodiment, the waste heat used to power the cooling
system is
provided from a fuel cell, which produces heat as one its by-products. Fuel
cell
technology has been contemplated by the current assignee and its related
companies
for powering more and more aircraft systems, particularly various galley (and
lavatory) systems, because it is a clean and efficient power source. However,
the
primary way to make fuel cell technology efficient is by using the fuel cell
by-
products (water, heat, and oxygen depleted air) in addition to the energy
created that
is created by the fuel cell. One way to use the heat created is by delivering
the heat to
an absorptive cooling system. It should be understood that the heat may be
provided
from other aircraft systems, such as waste heat from one or more of the on-
board
ovens, from the aircraft engines, from the water system, or any other
appropriate
source.
[0011] In one embodiment, there is provided a system 10 for absorptive
cooling
an aircraft trolley 12 or other compartment for use on board a passenger
transport
vehicle. As shown in Figure 1, a thermal conductive plate 14 is positioned on
the
back 16 of the trolley 12, and another thermal conductive plate 18 is
positioned on the
back of the galley trolley bay 20 (the space into which the trolley 12 is
stored) for
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thermal connection. A fan 22 may be provided inside the trolley in order to
generate
air distribution through the trolley and over the items contained therein.
This is an
example of an "air over trolley." The thermal plates transfer the cold
temperature that
is generated by the absorption cooler to the trolley interior. Contact between
the
plates 14, 18 creates a thermal connection for a cooling exchange between the
plates.
The thermal plates 14, 18 are mounted in such a way that they fully contact
(or can
otherwise be adjusted to fully contact) or substantially fully contact the
other thermal
plate to have maximum heat (cold) transfer. The transfer is conducted via
thermal
conductivity in the plates.
[0012] Figure 1 also illustrates that a heat source 24 is positioned behind
the
monument back wall 20 and associated with the absorption cooling system 10.
Waste
heat from the heat source 24 is used to power the absorption cooling system
10. In a
specific embodiment, the heat generated may be a by-product from a fuel cell
used to
power one or more aircraft systems.
[0013] A cooling fluid circuit 26 is also provided behind the back wall of
the
trolley bay 20. The coolant circuit 26 is associated with the thermal plate 18
of the
back wall, as well as with the absorption cooling unit. As waste heat (with a
temperature generally between about 50-90 C, and in some instances, between
60-
80 C) is transformed by the absorption cooler, the coolant circuit 26 delivers
the
cooled fluid to the thermal plate 18. Its contact with the thermal plate 14 of
the trolley
transfers the cold to the trolley 12. Fan 22 helps recirculate cooled air
inside the
trolley 12. Although the Figures show a single trolley being interfaced with a
single
galley wall, it should be understood that the coolant circuit 26 may route
cooled fluid
to any number of galley bay locations such that multiple trolleys may be
cooled at a
time.
[0014] An adjustment system may be provided to ensure contact between the
plates 14 and 18. Because the trolley has clearance and is moveable, an
adjustment
system may assure correct alignment of trolley to allow contact between the
plates.
[0015] Figure 2 shows an embodiment with a duct 28 that has a fan 29 for
air
distribution or recirculation through the trolley 12. Current installations
also have
ducting that may be connected to the air-chiller, which contains the cooling
parts
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and a fan to recirculate the air through the ducting and the trolley (referred
to as an
"air through trolley"). It is desirable to use standard trolleys in connection
with
this disclosure. In this
instance, the trolleys are provided with thermal
conductivity via plate 14, such that there is no need for electricity for the
internal
fan 22 as shown in Figure 1. In this embodiment, there are holes present on
the
back of the trolley, through will cold air may be forced into and through the
trolley. As the trolley is being cooled on the inside by means of the plate
14, the
fan can recirculate the air, creating a more steady atmosphere for the food/
drinks
inside the trolley. This is an example of an "air through trolley."
[0016] The schematic of Figure 3 shows how waste heat is delivered to an
absorption cooler that uses the heat to drive the cooling system. The cooled
fluid
may take a first path and be delivered to a compartment to be chilled, as
necessary.
It may also be delivered to the fluid coolant circuit to cool a galley wall
thermal
plate 18. The coolant circuit 26 may use any appropriate cooling fluid (such
as
refrigeration fluid, cooled air, cooled water, or any other fluid). In
addition, any
other form of heat/cold transportation can be used to deliver cooling fluid
between
the plates. Non-limiting examples include the thermal conductivity described,
the
use of heating pipes in contact, cooled air generation, and so forth.
[0017] As
discussed, in one aspect, thermal plate 18 on the monument aligns
with a thermal plate 14 that is mounted on the back of the trolley to generate
the
desired cooling effect. This system uses less power than an air chiller, it
uses waste
heat and thus improves efficiency, it provides cooling directly in the area
where it is
needed, and it provides a modular principle that can be used with each trolley
inside
the trolley bay.
[0018] Another embodiment that uses absorptive cooling technology for
chilling
trolleys is shown in Figures 4 and 5. This concept provides an envelope of
cooled air
around the trolley, rather than using a thermal plate directly positioned on
the trolley.
As shown in Figure 4, the trolley cooling system includes thermal cooling
plates 30
on the galley stowage area, and they may be included on the top (the view of
Figure 4
shows a top view so the top plate is not shown), back wall 36, as well as on
the
divider wall panels 38 between trolley storage areas. The cooling fluid from
the
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absorption cooler may be pumped through these plates 30, much like how the
cooling
fluid circuit cools the monument plate 18 described above. Providing a plate
30 on
the divider wall panel 38 allows the sides of two trolley carts 12 to be
cooled with a
single plate. This adds to efficiency of the system as the heat (cold)
transfer happens
on both sides. This creates a cooled or refrigerated area into which the
trolley can be
positioned. A door or other cooled air containment feature may be added to the
front
of the trolley bay stowage area, but is not necessary as cooled air is
generally
desirable in the aircraft galley and cabin areas.
[0019] The trolleys may include internal fans (as discussed above) to
help move
and recirculate cooled air through and over the items in the trolley to
improve cooling
efficiency and to create an even temperature range. External fans 40 may also
be
mounted to the back of the galley stowage space and are provided in order to
circulate
air over the trolley(s) to support the natural recirculation of air and to
keep the
temperature even in the trolley bay.
[0020] These embodiments can alleviate the need for a duct pipe that is
typically
provided at the back of the monument to deliver chiller air from the air
chiller to the
trolley. Providing even slight space gains can translate to major costs
savings for the
airline, as a few inches of space saved can mean additional passenger seats
that can be
added to the aircraft. One of the other benefits of the above-described
solutions is
that they do not require modifications to current trolley designs or sizes,
nor to the
current catering processes. They also reduce electricity loads on the aircraft
by
providing cooled air using waste heat from fuel cells or other sources.
[0021] Changes and modifications, additions and deletions may be made to
the
structures and methods recited above and shown in the drawings without
departing
from the scope or spirit of the invention and the following claims.
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