Note: Descriptions are shown in the official language in which they were submitted.
Title
RADIATOR CONFIGURATION
Scope of the Invention
[0001] This invention relates to modular fractoring pump units each
comprising a road
vehicle carrying a pump, an engine to drive the pump and radiators to cool the
engine; and
more particularly to a radiator configuration and arrangement for mounting the
radiator on
the road vehicle to permit advantageous cooling of the engine when a plurality
of these road
vehicles are parked side to side closely together in an array.
Background of the Invention
[0002] Hydraulic fractoring is known as, for example, disclosed in U.S.
Patent 7,063,147
to Siebrits eta!, issued June 20, 2006 and U.S. Patent 7,788,037 to Soliman,
issued August 31,
2010. U.S. Patent 7,845,413 to Shampine, issued December 7, 2010, teaches a
typical manner
of providing a plurality modular fract pumping units coupled together.
[0003] Hydraulic fractoring is a known process which requires heavy duty
pumps known
as fract or fractoring pumps which typically comprise high pressure pumps
operating on
typically diesel generators generating in the range of 2000 horsepower. A
large number of
such pumps are generally provided in an array to provide the necessary high
pressure and
large volume of fluids required for hydraulic fractoring at a remote location.
The pumps are
known to be provided as part of a modular mobile fract pump unit comprising a
road
compatible vehicle such as a customized flat bed trailer on which there is
mounted the pump,
an internal combustion engine to drive the pump and a radiator to cool the
engine. The
trailers of each unit are typically parked close together in an array side by
side with the pump
and a typically rigid discharge outlet for the pump at a rear end of the unit
and the radiator at a
front end of the unit. A central manifold can be provided for coupling of the
rigid discharge
outlet of each modular mobile fract pump unit at set spaced locations along a
central manifold
trunk moved towards or away from the manifold trunk. Each modular mobile fract
pump unit
when accurately located relative the manifold trunk can independently be
coupled to the
manifold or removed for replacement. The manifold trunk establishes a set
spacing of the
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trailers of the units in the array side by side as, for example, on 11.5 foot
(138 inches) centers.
For the modular mobile fract pump unit to be road worthy on Interstate
highways in the USA,
the unit preferably has a width not greater than 8.5 feet (102 inches.). With,
for example, 11.5
foot centers for the pump discharge outlets, this provides for a 3 feet (36
inch) spacing
between the sides of adjacent side by side units.
[0004] The internal combustion engine on each mobile fract pump unit
typically is a
diesel engine. Each diesel engine requires a large radiator to cool the
engine. Known radiator
structures often provide for two heat exchangers. Prior art devices such as
the fractoring
system shown in U.S. Patent 7,845,413 to Shampine illustrate horizontally
disposed radiators
for air flow vertically therethrough. The horizontally disposed radiators
extend horizontally
for air flow vertically therethrough with the air to pass firstly upwardly
through a lower heat
exchanger and then secondly upwardly through an upper heat exchanger above the
lower heat
exchanger. This stacked upper and lower heating exchanger configuration has
been selected
typically to provide the cooling requirements for the engine within the
maximum width for the
vehicle unit to be road worthy on Interstate highways in the USA. The stacked
upper and
lower heating exchanger configuration has the disadvantage that atmospheric
air is heated by
passing through the lower heat exchanger before the heated air flows upwardly
through the
second heat exchanger, thus reducing the cooling capacity of the second heat
exchanger. As
well, the stacked upper and lower heating exchanger arrangement renders it
different to clean
each heat exchanger after use.
Background of the Invention
[0005] To at least partially overcome these disadvantages of previously
known devices,
the present invention provides a modular mobile fract pump unit having for a
radiator with a
heat exchanger vertically for generally horizontal flow of air through the
radiator and a duct
provided on an air exit side of the heat exchanger to direct air exiting the
heat exchanger
upwardly. Preferably, the duct comprises a retractable duct for movement
between an
operative position for use in parked cooling operation and a storage position
for transport of
the unit as a road worthy vehicle, within the storage position the duct not
increasing the
overall width of the unit and in the operative position the duct extending
laterally to the side
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of the unit beyond the storage position and increasing the overall width of
the unit.
Preferably, the duct is provided with cleaning access doors opening
therethrough which can
be opened to access the radiator for cleaning. Preferably, a pair of radiators
are provided,
one along on each side of the vehicle, with the ducts opening outwardly.
[0006] Preferably, a roof member may be provided to bridge laterally
between two
radiators proximate the top of the radiators. A fan is provided on the
interior of each radiator
to direct flow laterally outwardly through each radiator. With the roof member
in place, the
roof member requires air to be passed through the radiators to be drawn
laterally from the
front or rear or below the radiators reducing the likelihood that heated air
discharged vertically
from each duct may be drawn down into the fan and passed again through the
radiator.
[0007] Vehicles carrying radiators in accordance with the present invention
can be
parked relatively close together side by side as, for example, within three
feet of each other in
which the case the ducts would extend to one side, about eighteen inches so
that the ducts
effectively meet.
[0008] As the radiators preferably have a substantial height and size, to
provide for
manual closing of the ducts, an arrangement is provided which permits a person
on the
ground to open and close the radiators avoiding the need to climb the unit and
dangers
associated therewith. Access doors are provided laterally of the unit through
each duct
which, preferably when each duct is in a closed position, can be opened by a
person on the
ground to facilitate the radiators being cleaned as in a known manner by the
passage of
water through the heat exchangers.
[0009] In one aspect, the present invention provides a modular mobile pump
unit
comprising:
an elongate mobile trailer having a first side, a second side, a front and a
rear,
the trailer having a longitudinal centerline between the first side and the
second
side,
the trailer having mounted thereon a pump to dispense a fluid, an internal
combustion engine to power the pump, a first air cooled radiator to cool the
engine and a
second air cooled radiator to cool the engine,
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the first radiator comprising a vertically extending first heat exchanger for
passage of air horizontally therethrough to cool a fluid from the engine
circulated within the
first heat exchanger and a first fan to blow atmospheric air through the first
heat exchanger,
the first radiator mounted to the trailer on the first side of the
longitudinal center
line proximate the first side with the first heat exchanger adjacent the first
side and with the
first fan laterally inwardly of the first heat exchanger, the first fan
providing for passage of
air through the first heat exchanger horizontally and laterally outwardly
toward the first side
of the trailer,
the first radiator having a first duct member carried on the first radiator at
a
location laterally outwardly of the first heat exchanger and in the flow path
of air from the
first fan exiting horizontally and laterally from the first heat exchanger,
the first duct member movable relative to the first radiator from a storage
position
in which the first duct member does not extend laterally outwardly beyond the
first side of
the trailer and an operative position in which the first duct member extends
laterally
outwardly beyond the first side of the trailer,
in the operative position the first duct member receiving air passing
laterally from
the first heat exchanger and directing this air to exit vertically upwardly
from a first duct
outlet disposed along an upper edge of the first duct member,
the second radiator comprising a vertically extending second heat exchanger
for
passage of air horizontally therethrough to cool a fluid from the engine
circulated within the
second heat exchanger and a second fan to blow atmospheric air through the
second heat
exchanger,
the second radiator mounted to the trailer directly opposite the first
radiator on the
second side of the longitudinal center line proximate the second side with the
second heat
exchanger adjacent the second side and with the second fan laterally inwardly
of the second
heat exchanger, the second fan providing for passage of air through the second
heat
exchanger horizontally and laterally outwardly toward the second side of the
trailer,
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the second radiator having a second duct member carried on the second radiator
at
a location laterally outwardly of the second heat exchanger and in the flow
path of air from
the second fan exiting horizontally and laterally from the second heat
exchanger,
the second duct member movable relative to the second radiator from a storage
position in which the second duct member does not extend laterally outwardly
beyond the
second side of the trailer and an operative position in which the second duct
member extends
laterally outwardly beyond the second side of the trailer,
in the operative position the second duct member receiving air passing
laterally
from the second heat exchanger and directing this air to exit vertically
upwardly from a
second duct outlet disposed along an upper edge of the second duct member.
Preferably, the
invention provides an array of such units wherein the units are arranged side
by side with a
spacing between adjacent units at least equal to a spacing distance
represented by the sum of
a distance that the first duct member in the operative position extends beyond
the first side of
the trailer and a distance that the second duct member in the operative
position extends
beyond the second side of the trailer.
Brief Description of the Drawings
[0010] Further aspects and advantages of the present invention will become
apparent
from the following description taken together with the accompanying drawings
in which:
[0011] Figure 1 is a perspective rear view of a modular mobile pump unit in
accordance
with the present invention in conjunction with a tractor;
[0012] Figure 2 is a schematic front perspective view of a skid platform
and the radiators
shown in Figure 1 in a storage position;
[0013] Figure 3 is a front view of Figure 2;
[0014] Figure 4 is a schematic front perspective view the same as Figure 2
but showing
the radiators in an operative position;
[0015] Figure 5 is a front view of Figure 4;
[0016] Figure 6 is a schematic cross-sectional front view along section
line 6-6' in Figure
4 showing the right hand side radiator;
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[0017] Figure 7 is a schematic perspective view illustrating a mechanism
for movement
of the duct member between the storage position and the operative position;
[0018] Figure 8 is a perspective view the same as Figure 2 but showing
access doors in
an open position;
[0019] Figure 9 is a schematic top view showing a plurality of units in
accordance with
Figure 1 arranged in two rows, one on either side of a central manifold;
[0020] Figure 10 is an enlarged view of the front portions of three of the
units shown in
Figure 9 showing the units as being spaced an equal distance apart; and
[0021] Figure 11 is a perspective view the same as Figure 4 but
additionally showing a
roof baffle.
Detailed Description of the Drawings
[0022] Figure 1 shows a modular pump mobile unit 10 in accordance with the
present
invention. The mobile 10 comprises a standard trailer 12, a fluid pump 14, a
diesel motor 15
that drives the pump 14 and a pair of radiators 20 and 21 for cooling the
diesel motor 15. The
trailer 12 is removably coupled to a tractor 16 for ease of transportation.
The pump 14 has a
intake pipe 17 for receiving fluid at a low pressure and a discharge pipe 18
for discharging
fluid at a high pressure.
[0023] The unit 10 and the trailer 12 have a first side 22, a second
parallel side 23, a front
24 and a rear 26. As seen in Figure 10, the unit 10 and the trailer 12 have a
longitudinal center
line 27 which extends longitudinally of the unit 10 and the trailer 12 between
the first side 22
and the second side 23.
[0024] Referring to Figure 9, an array of mobile modular units 10 is
arranged on opposite
sides of a fluid manifold 30. The manifold 30 extends along a manifold
longitudinal 31. The
manifold includes a low pressure liquid line 32 and a high pressure discharge
line 34. The
intake pipe 17 from each unit 10 is adapted to be removably coupled to a
corresponding
outlet pipe 35 of the low pressure liquid line 32 and the discharge pipe 18 of
each unit 10 is
adapted to be removably coupled to a corresponding inlet pipe 36 of the high
pressure
discharge line 34. The low pressure liquid line 32 has the outlet pipe 35
located at equally
spaced fixed distances along the longitudinal 31 of the manifold. The high
pressure discharge
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line 34 has the inlet pipes 36 located at correspondingly spaced fixed
distances along the
longitudinal 31 of the manifold 30. Each inlet pipe 36 includes a valve 37 and
each outlet
pipe includes a valve 38 to selectively independently peimit or prevent flow.
Each unit 10 is
preferably located with its longitudinal center line 27 perpendicular to the
longitudinal 31 of
the manifold 30. Each mobile unit 10 may be disconnected from the manifold 30
and
independently moved forwardly or rearwardly for replacement by another modular
unit 10.
[0025] As can be seen in Figure 1, the trailer 12 has a deck 13 including a
skid portion 39
upon which the radiators 20 and 21 are schematically shown as being mounted.
For ease of
illustration, in each of Figures 2 to 5, the radiators are shown as mounted on
the skid 39
without illustrating other components of the unit 10.
[0026] Reference is made to Figure 6 which is a schematic cross-sectional
view along
section line 6-6' of the first radiator 20. The first radiator 20 has a first
heat exchanger 40.
The first heat exchanger 40 includes a top header 41 and a bottom header 42
with a core 90
of vertically extending cooling tubes 43 extending vertically between the top
header 41 and
the bottom header 42. A fluid inlet 44 delivers fluid from the cooling system
of the motor 15
to the bottom header 42. A fluid outlet 45 is connected to the top header 41
and delivers
cooled fluid from the top header 41 back to the cooling system of the motor
15. Thus,
cooling fluid from the motor 15 is to be circulated in a cooling circuit, only
part of which is
shown, to pass from the fluid inlet 44 into the bottom header 42 vertically
through the
cooling tubes 43 to the top header 41 and then out the fluid outlet 45 to
return to the engine.
As will be appreciated, a suitable circulating pump (not shown) is provided to
circulate the
cooling fluid through the first heat exchanger 40.
[0027] The first radiator 20 includes a system for passing atmospheric air
through the
core of the first heat exchanger past the cooling tubes 43 so as to reduce the
temperature of
the cooling fluid circulated through the cooling tubes 43. In this regard, as
schematically
shown in Figure 6, a fan 46 is rotatable about a horizontal fan axis 47 within
a cylindrical fan
casing 48 so as to draw atmospheric air inwardly through openings 49 in the
fan casing and
force the air horizontally and laterally outwardly through the core 90 and
past the cooling
tubes 43. As seen in Figure 6, the fan 46 directs air flow laterally outwardly
in a direction
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from the longitudinal center line 27 laterally outwardly toward the first side
22. In this
regard, the first heat exchanger 40 may be considered to have an air inlet
opening 50 on the
laterally inward side of the cooling tubes 43 and an air outlet opening 51 on
a radially
outwardly side of the cooling tubes 43.
[0028] The first radiator 20 has a first duct member 52 which in Figure 6
is illustrated as
being in an operative position permitting air flow from the fan 46 laterally
outwardly through
the air outlet opening 51 and then upwardly through the duct member 52 to exit
upwardly
through a first duct outlet 54 open to the atmosphere. As seen in Figure 6,
the first duct
outlet 54 is disposed along an upper edge 55 of the first duct member 52.
[0029] Each of the first radiator 20 and the second radiator 21 has
identical components
and each is located on a respective side of the longitudinal center line 27 of
the trailer 12.
The radiators 20 and 21 can be virtually identical but for arrangements so as
to be suitably
located adjacent either the first side 22 or the second side 23. For ease of
discussion, each of
the individual elements of the second radiator 21 will be referred to by the
same reference
numerals used to refer to the elements of the first radiator 20.
[0030] The duct member 52 of the radiators 20 and 21 are movable between
operative
positions as shown in Figures 4 and 5 which permit air flow upwardly from the
duct outlets
54 and storage positions as shown in Figures 2 and 3 which substantially close
the air outlets
51. As seen in end view in Figure 3, with the radiators 20 and 21 and the duct
members 52 in
the storage position, the radiators 20 and 21 do not extend outwardly beyond
the trailer first
side 22 or the second side 23. In contrast, as seen in end view in Figure 5,
in the operative
position, the duct members 52 extend laterally beyond the sides of the
trailer, with the duct
member 52 of the first radiator 20 extending beyond the trailer first side 22
and the duct
member 52 of the second radiator 21 extending beyond the second side 23.
[0031] Reference is made to Figure 10 which is a schematic enlargement of
front
portions of three units 10 shown in Figure 9 arranged side to side and in
which the left hand-
most trailer is shown with its radiators 20 and 21 having their duct members
52 in the storage
position, the middle unit 10 is shown as having its radiators 20 and 21 with
its duct members
52 in the operative position and the right hand unit 10 is illustrated as
having its second
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radiator 21 with its first duct member 52 in an operative position and its
first radiator 20
having its duct member 52 in a storage position. In Figure 10, the width of
each unit 10 is
illustrated as W with a width of each of the three units 10 being indicated as
identical. The
center line 27 for each unit 10 is shown and the distance between center
lines, De is shown
and is indicated as being identical. The units 10 are shown as arranged side
by side with a
spacing between units indicated as S and which such spacing S being
represented as equal to
two times the distance De that duct member 52 extends laterally from the
respective side of
its respective unit 10. In a preferred embodiment as illustrated in Figures 9
and 10, the inlet
pipes 36 for the high pressure discharge line 34 and the outlet pipes 35 for
the low pressure
fluid line 32 may be spaced along the manifold longitudinal 31 a distance
equal to Dc shown
in Figure 10. Preferably, the distance De is equal to the width W of a trailer
plus at least
twice D, the distance that each duct member 52 extends from a trailer. Such an
arrangement
provides for optimal usage of the spacing between units 10 for discharge of
air upwardly.
Preferably, the width of a trailer is a maximum width which permits the
trailer to be
roadworthy, for example, 102 inches. Preferably, the distance De is in the
range of 12 to 24
inches, preferably 18 inches and the units 10 as well as the outlet pipes 35
and the inlet pipes
36 are spaced a distance of D, of about 138 inches.
[0032] Reference is made to Figure 4 which illustrates a preferred
configuration for each
duct member 52. The duct member 52 has a side wall 70, a front wall 71 and a
rear wall 72.
The side wall 70 is mounted to a rectangular frame 73 of a casing 74 for each
radiator that
contains the heat exchanger 40 and provides the passageway for air flow. The
frame 73
effectively defines the air outlet opening 51 for passage of air laterally
outwardly through the
core and its cooling tubes 43. The duct member 52 is pivotally mounted to the
frame 73 for
pivoting at its lower end about a horizontal axis generally indicated as 75.
Each of the front
wall 71 and the rear wall 72 is formed from two triangular gusset members 76
and 77, each
mounted by hinge members extending along the edges of each gusset member such
that with
pivoting of the side wall 70 about the horizontal axis 75, the gusset members
fold inwardly
upon themselves in a manner not dissimilar to that of a pleat in an accordion.
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[0033] An actuator member 79 is provided for moving each of the duct
members 52
between the operative position and the storage position. As seen in Figures 4
and 6, a
vertical strut 80 is mounted to the frame 73 and pivotably carries a first
pivot arm 81 which is
pivotably coupled to a second pivot arm 82 pivotably coupled to the center of
the side wall
70. As illustrated in Figure 7, the actuator mechanism includes a rotatable
rod 83 which is
mounted to a lower portion of the frame 73 and extends upwardly to an actuator
link 84
engaging the first pivot arm 81. With rotation of a crank handle 85, shown in
Figure 7, the
actuator link 84 is moved upwardly or downwardly and thus pivots the first and
second pivot
arms so as to move the duct member 52 toward the operative position by moving
the pivot
arms upwardly and to move the duct member 52 toward the storage position by
moving the
pivot arms downwardly.
[0034] The crank handle 85 is located at a height on the unit 10 to be
accessible by a
person standing on the ground without the need for the person to climb the
unit 10 or its
trailer 12. The crank handle 85 is to be provided so as to avoid interference
in use with other
portions of the unit 10 such as the trailer 12 or the skid 39 albeit, in the
embodiments for ease
of illustration, the crank handle 85 appears to be in interference with the
skid 39. As can be
seen in Figure 4, with the side wall 70 in the operative position, the duct
outlet 54 is open
upwardly to the atmosphere for discharge of air upwardly.
[0035] Reference is made to Figure 8 which illustrates the duct members 52
in a closed
position, however, with access doors 88 on the duct member 52 shown as being
in an open
position. As seen in Figure 8, the side wall 70 of each duct member 52 is
provided with two
rectangular access openings 89 therethrough. An access door 90 is provided
coupled by a
vertically extending hinge 92 to an edge of each access opening 89. The access
doors 88 are
movable from a closed position as shown in Figure 2 which closes the side wall
70 to air flow
therethrough and an open position as shown in Figure 8 in which the access
doors provide
access to the heat exchanger 40 therein and, more particularly, to the core of
the heat
exchanger and the cooling tubes 43. With the access doors 88 in the open
position as shown
in Figure 8, a person on the ground can access the core 90 and its cooling
tubes 43 for cleaning
as, for example, with a user to hold a hose to discharge a stream of air or
water to engage the
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core and its cooling tubes 43 to clean the outside of the cooling tubes from
various matters
such as dust, dirt, mud and the like which may have come to be engaged upon
the cooling
tubes during use and typically which impedes efficient heat transfer. Of
course, the core and
its cooling tubes 43 may have various cooling fins 70 which may be placed
close together and
from which debris such as dust, dirt and mud may preferably be removed in
cleaning on a
regular basis to maintain the efficiency of the heat exchanger. Figure 8
schematically shows
four vertically extending cooling tubes 43 and two longitudinally extending
cooling fins 70
although a large number typically are to be provided.
[0036] The access doors 88 are located on the radiators 20 and 21 at a
location that a
person standing on the ground can manually move the access doors between the
open and
closed positions and to latch the doors in the open and closed positions.
Various latching
arrangements may be used as they are accessible from the ground and are used,
for example,
to close the doors at the rear of box trailers and the like. A latching
arrangement 72 is
schematically illustrated in Figure 2 only. Vertically extending lock rod 73
rotatably
supported on each door 88 and pivotable by a handle 74 between coupled and
uncoupled
conditions with cam latches 75 and 76 carried on the front wall 70 above and
below each
door 88 and are of the type disclosed in U.S. Patent 2,038,876 to Sonabend,
issued April 28,
1936. The handle 74 is accessible to a person on the ground. Once unlatched,
each door 88 is
accessible to a person on the ground to pivot each door between open and
closed positions.
[0037] In the preferred embodiments, the heat exchangers are shown with a
core which
has vertically extending cooling tubes 43. In accordance with the invention,
it is not
necessary that the cooling tubes 43 extend vertically. For example, in a
similar heat
exchanger, the cooling tubes may extend horizontally. Referring to Figure 6,
in addition to
the primary core 90 having vertically extending cooling tubes 43, a secondary
core 91 is
shown schematically to have horizontally extending cooling tubes 92.
[0038] In the preferred embodiment, the trailer first side 22 and the
trailer second side 23
are shown as providing substantially in the same vertical plane, a laterally
most extending
surface of the unit 10, the trailer 12, the trailer deck 13, its skid 39 and
each of the radiators
20 and 21. It is to be appreciated that a unit 10 with the duct members 52 in
the storage
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position, the unit 10 will have a width defined by a laterally outermost
surface. The laterally
outermost surface may comprise the side wall 70 of one of the radiators with,
for example,
the skid 39 or the trailer deck 13 or the portions of the trailer disposed
laterally inwardly
therefrom.
[0039] In the preferred embodiment, the duct member 52 is illustrated to
assume an
operative position in which the duct member 52 extends laterally from the unit
10 farther in
the operative position than in a storage position. The particular
configuration of the duct
member 52 is not limited. The preferred duct member 52 illustrated hinges
about the
horizontal hinge axis 75 at the bottom of the duct member 52. This is not
necessary. The
duct member 52 could be provided to merely slide laterally to one side and,
for example, to
extend in the operative position farther laterally outwardly over its whole
height than when in
the storage position.
[0040] The duct member 52 is shown as having its front wall 71 and its rear
wall 72
formed from gusset members which fold to collapse upon themselves when a duct
member
52 is moved to the storage position. This is not necessary and each of the
front wall 71 and
the rear wall 72 could be rigid members which slide laterally into slots
provided on the
radiator of a casing 74. Similarly, rather than provide the front wall 71 and
the rear wall 72
from rigid gusset members, each wall could be provided as from a flexible
member as, for
example, from a flexible elastomeric member or fabric.
[0041] Reference is made to Figure 11 which illustrates a second embodiment
in
accordance with the present invention and which is identical to the first
embodiment with the
first exception that a roof member 93 is provided bridging between the first
radiator 20 and
the second radiator 21 laterally inwardly of the duct outlet 54 on each side
of the unit 10 and
above the fans 46 and their fan casings 48. Between the casing 74 enclosing
each heat
exchanger 40, and beneath the roof member 93, a forward air inlet 94 and rear
air inlet 95 is
provided via which atmospheric air may be drawn into the fan as indicated by
the arrows 96
and 98. Air drawn into the fans 46 is directed through the heat exchangers 40
to exit
upwardly from the duct outlets 54 as indicated by the arrows 98 and 99.
Providing the roof
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member 93 assists in reducing the likelihood that heated air exhausted
upwardly from the
duct outlets is drawn back into the fans.
[0042] Figure 11 differs from the first embodiment in showing schematically
a bottom air
inlet 100 provided through the skid portion 39 and which permits air from
below the deck 39
of the trailer 12 into the fan 46 as indicated by arrow 101. The bottom air
inlet 100 can be
accommodated with suitable ducting or apertures through the skid portion 39
and deck
underneath the fans 46. Figure 11 further shows as also shown schematically in
Figure 6 the
deck 39 to be cut away under the fan 46 to provide the bottom air inlet 100
and petinit air
flow upwardly as indicated by arrow 100. Figures 11 and 6 also show one lower
horizontal
air inlet 102 shown to be formed internally within the deck 39 to permit air
flow horizontally
from the side as indicated by arrow 103 to the fan 46. The lower horizontal
air inlet 102 may
be provided, one on each side, whether or not a bottom air inlet 100 is
provided.
[0043] While the invention has been described with reference to the
preferred
embodiments, many variations and modifications will now occur to a person
skilled in the
art. For a definition of the invention, reference is made to the accompanying
claims.
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