U.S. patent application number 12/622744 was filed with the patent office on 2010-10-07 for compact marine air conditioning unit with optional electric heat.
Invention is credited to Alain A. Mabru.
Application Number | 20100251739 12/622744 |
Document ID | / |
Family ID | 42825047 |
Filed Date | 2010-10-07 |
United States Patent
Application |
20100251739 |
Kind Code |
A1 |
Mabru; Alain A. |
October 7, 2010 |
COMPACT MARINE AIR CONDITIONING UNIT WITH OPTIONAL ELECTRIC
HEAT
Abstract
A package marine air conditioning unit places an evaporator coil
on the inlet side of an enclosing cabinet, an axial supply fan on
an opposing outlet side of the cabinet, and a compressor disposed
between the evaporator coil and the supply fan. Locating the
compressor within the air stream on the leaving air side of the
evaporator coil allows cold air to flow around the compressor
thereby providing beneficial compressor cooling. An axial flow
supply fan located downstream of the compressor functions to draw
return air in a generally lineal flow path across the evaporator
coil and around the compressor, for discharge in an axial direction
thereby resulting in a generally linear air flow path through the
unit. A cabinet is provided to enclose the components thereby
allowing for the installation of electric heating elements.
Enclosing the components within a cabinet avoids the need to paint
or otherwise coat the enclosed components thereby reducing
manufacturing costs.
Inventors: |
Mabru; Alain A.; (Parkland,
FL) |
Correspondence
Address: |
MALIN HALEY DIMAGGIO BOWEN & LHOTA, P.A.
1936 S ANDREWS AVENUE
FORT LAUDERDALE
FL
33316
US
|
Family ID: |
42825047 |
Appl. No.: |
12/622744 |
Filed: |
November 20, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61166308 |
Apr 3, 2009 |
|
|
|
Current U.S.
Class: |
62/240 ;
62/498 |
Current CPC
Class: |
B63J 2/04 20130101 |
Class at
Publication: |
62/240 ;
62/498 |
International
Class: |
B63B 38/00 20060101
B63B038/00; F25B 1/00 20060101 F25B001/00 |
Claims
1. A marine air conditioning system comprising: a supply fan having
an inlet for drawing air in from a first direction and an outlet
and discharging air out in a second direction, said second
direction being generally opposite of said first direction; a
helical water-to-refrigerant condenser having a refrigerant inlet
and a refrigerant outlet, and a water inlet and water outlet, said
water inlet in fluid communication with a water source; a
refrigerant compressor having a refrigerant inlet, and a
refrigerant outlet in fluid communication with said condenser
refrigerant inlet; a evaporator coil disposed generally
perpendicular to said first direction, said evaporator coil
including a face area having an entering air side and a leaving air
side, said evaporator coil further including a refrigerant inlet in
fluid communication with said condenser outlet and a refrigerant
outlet in fluid communication with said compressor refrigerant
inlet; said compressor generally disposed between said supply fan
inlet and said evaporator coil leaving air side, whereby said
compressor is within the air flow path of air leaving said
evaporator coil and entering said fan inlet.
2. A marine air conditioning system according to claim 1, further
including a cabinet for substantially enclosing said evaporator
coil, said compressor, said condenser, and said fan.
3. A marine air conditioning system according to claim 1, further
including an electric heat element.
4. A marine air conditioning system according to claim 1, wherein
said supply fan comprises an axial fan.
5. A marine air conditioning system according to claim 4, wherein
said supply fan is disposed downstream relative to said evaporator
coil in a draw thru configuration.
6. A marine air conditioning system according to claim 1, wherein
said helical water-to-refrigerant condenser is disposed in
generally surrounding relation with said supply fan.
7. A marine air conditioning system according to claim 1, wherein
said helical water-to-refrigerant condenser is disposed in
generally surrounding relation with said compressor.
8. A marine air conditioning system comprising: a vapor compression
system having components including a compressor, an evaporator
coil, a condenser coil, and a supply fan operatively connected to
thermally condition air; a cabinet substantially enclosing said
components, said cabinet having an inlet end and an opposing
discharge end; said evaporator coil disposed in proximity to said
cabinet inlet end; said supply fan disposed in proximity to said
outlet end and configured to draw air in from said cabinet inlet
end across said evaporator coil and to discharge air out from the
cabinet discharge end; said compressor mounted generally between
said evaporator coil and said supply fan; said condenser coil
comprising a generally helical water-to-refrigerant heat exchanger
disposed in surrounding relation with said compressor.
9. A marine air conditioning unit according to claim 8, further
including an electric heat element.
10. A marine air conditioning unit according to claim 8, wherein
said supply fan comprises an axial fan.
11. A marine air conditioning unit according to claim 8, wherein
said supply fan is remotely located from said cabinet, said supply
fan having an inlet connected in fluid communication with said
cabinet interior via a duct.
12. A marine air conditioning system for thermally conditioning air
within a conditioned space, said system comprising: a vapor
compression system having components including a refrigerant
compressor, an evaporator coil, a condenser, and a supply fan, said
components functioning to thermally condition air; a cabinet
substantially enclosing said components, said cabinet having an
inlet end and an opposing discharge end; said evaporator coil
disposed in proximity to said inlet end, said evaporator coil
having an entering air side and a leaving air side; said supply fan
having an inlet configured to draw air across said evaporator coil;
said compressor disposed between the leaving air side of evaporator
coil and said supply fan inlet such that air coming of the leaving
air side of said evaporator fan circulates around said compressor
thereby providing beneficial compressor cooling to increase
compressor efficiency; and said condenser coil comprising a
generally helical water and refrigerant heat exchanger disposed in
surrounding relation with said compressor such that air coming of
the leaving air side of said evaporator fan circulates around said
condenser coil thereby providing beneficial condenser coil cooling
to increase.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of provisional U.S.
Patent Application Ser. No. 61/166,308 filed on Apr. 3, 2009.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] N/A
COPYRIGHT NOTICE
[0003] A portion of the disclosure of this patent document contains
material that is subject to copyright protection. The copyright
owner has no objection to the facsimile reproduction by anyone of
the patent document or patent disclosure as it appears in the
Patent and Trademark Office patent file or records, but otherwise
retains all copyright and all other rights reserved.
BACKGROUND OF THE INVENTION
[0004] 1. Field of the Invention
[0005] The present invention relates generally to marine air
conditioning systems, and more particularly to a compact,
self-contained water cooled package air conditioning system for the
marine industry.
[0006] 2. Description of Related Art
[0007] Air conditioning ("A/C") systems have been installed on
marine vessels for many years. Marine air conditioning systems are
typically comprised of water cooled vapor-compression refrigeration
system, configured as packaged or split systems that function in
either straight cool or heat pump modes. These systems are
typically specially designed for installation on marine vessels
wherein space is extremely limited and quiet operation is required.
The installation of air conditioning systems in marine vessels is
wrought with difficulties and limitations that are unique to such
applications.
[0008] As used herein the term "package system" shall mean an air
conditioning system wherein the compressor, condenser coil,
evaporator coil, and evaporator fan are installed in close
proximity, typically manufactured as an installable unit. As used
there the term "split system" shall mean an air conditioning system
wherein at least the compressor is mounted remote from the
evaporator coil.
[0009] In marine vessel installations, the use of split systems is
primarily driven by a desire to locate the compressor in a remote
area, such as the engine room, in order to reduce noise
transmission to the occupied cabins and parts of the vessel. The
use of split systems results in significantly increased
installation costs, and requires running refrigerant lines
throughout the vessel to connect the compressor to a remotely
located evaporator coil. Accordingly, there is a strong preference
for the use of package systems.
[0010] One significant limitation presented when attempting to
install package A/C units on a marine vessel involves is a lack of
space. More particularly, space on marine vessels is very limited,
and interior rooms and cabins often present little or no unused or
free space to accommodate the installation of an air conditioning
unit. Accordingly, an important characteristic of a marine air
conditioning unit is compact size. Another problem experienced with
marine air conditioning units involves excessive sound/noise
levels. Space limitations often dictate that marine air
conditioning systems be installed in proximity to frequently
occupied spaces such as cabins and sleeping quarters. For example,
package A/C units are often installed under seats, benches, and
beds, within rooms and spaces that are frequently occupied. As a
result of such limitations, advancements in marine air conditioning
units that result in quieter operation are important.
[0011] A further problem experienced with conventional marine air
conditioning units relate to performance. Efforts to minimize the
size marine A/C systems have resulted in component configurations
wherein the distance between the evaporator coil and the evaporator
fan inlet is very small. Such configurations have been found to
perform unsatisfactorily. A common problem experienced with such
configurations is the formation of ice on the evaporator coil. The
icing problem is a result from uneven air flow across the coil due
to the close spacing of the evaporator coil and the supply fan
inlet, which causes low face velocities along the coil periphery.
In an attempt to rectify such problems, some models incorporate
complex control schemes that temporarily terminate cooling mode
operation in an attempt to de-frost the evaporator coil thereby
interrupting the flow of cold air to the conditioned space. Another
problem associated with package marine air conditioning units in
the art involves the migration of moisture from the coil into the
discharge airstream resulting from localized excessive air velocity
across the coil. Moisture drawn from the coil into the discharge
airstream is supplied to the conditioned space thereby raising the
humidity level.
[0012] A further problem found in package marine air conditioners
in the art involves the location of the compressor. More
particularly, prior art designs (both packaged and split systems)
typically locate the compressor in an area that is not exposed to
air flow thereby failing to cool the compressor leading to
compressor overheating. In other designs the compressor is located
upstream of the evaporator coil and thus is exposed to relatively
warm return air. Both of said locations fail to provide the
compressor with adequate ambient cooling resulting in performance
degradation.
[0013] Yet another limitation present with commercially available
package marine A/C units involves air flow paths. In particular,
conventional package marine A/C units typically use centrifugal
fans to draw air across the evaporator coil and supply cold air to
the conditioned space. A centrifugal fan typically draws air in
from one direction and discharges the air in a direction that is
generally perpendicular to the inlet direction. Accordingly, the
air flow path through such package A/C units follows an L-shaped
(i.e. 90-degree) path. The present inventor has found that an
L-shaped air-flow path renders installation exceedingly difficult
in a large number of cases wherein the available space is long and
narrow leaving little if any room to re-direct the air 90-degrees
from the evaporator coil inlet to the supply fan outlet.
[0014] An example of a package prior art marine U.S. Pat. No.
5,848,536, issued to Dodge et al., which discloses a self-contained
marine air conditioner having the limitations and disadvantages
discussed above. Dodge discloses a self-contained marine air
conditioning unit wherein, in an effort to minimize overall size,
the distance between the evaporator coil and evaporator fan intake
is relatively small. The design disclosed by Dodge, however, failed
to significantly reduce noise as a result of positioning the blower
in close proximity to the evaporator coil thereby allowing blower
sound to propagate from the unit. The design disclosed by Dodge, is
further burdened by evaporator coil freeze-up (e.g. icing)
resulting from the close spacing between the evaporator coil and
blower inlet in the draw-thru configuration (e.g. wherein air is
drawn across the evaporator coil), which configuration results in
uneven airflow across the coil. Finally, the Dodge system places
the compressor outside of the air stream thereby relying on solely
on internal refrigerant flow to cool the compressor. It has been
found, however, that in warm operating conditions this system is
prone to compressor overheating, and in cold operating conditions
liquid refrigerant has been found to migrate back to the
compressor, both undesirable situations can lead to compressor
failure. A further limitation present with the configuration
disclosed by Dodge, as well as all other configurations that do not
incorporate a cabinet or enclosure to house the components is the
inability to incorporate electric heat. As seen in the Dodge
reference, the major components, namely the compressor, evaporator
coil, condenser, etc. are mounted on a base frame or chasis
essentially exposed without a protective cabinet. One disadvantage
of exposing the components involves the inability to incorporate
electric heating elements due as exposed heating coils would be a
fire hazard.
[0015] As should now be apparent, self-contained marine air
conditioning units, such as the one disclosed by Dodge, are
burdened with significant limitations and disadvantages.
Accordingly, there thus exists a need for an improved, compact,
self-contained marine air conditioning unit that is more practical,
reliable, quieter, cost effective, and smaller, than units
currently available.
BRIEF SUMMARY OF THE INVENTION
[0016] The present invention overcomes the limitations and
disadvantages present in the art by providing an improved compact
package marine A/C system particularly well adapted for
installation and use within marine vessels, while providing a
system that is more practical, reliable, quieter, and smaller. A
package marine A/C unit in accordance with the present invention
places the evaporator coil on the inlet side of the unit with the
compressor between the evaporator coil leaving air side and the
supply fan inlet. Locating the compressor within the conditioned
air stream on the leaving air side of the evaporator coil allows
cold air to flow around the compressor thereby providing beneficial
compressor cooling. An axial flow supply fan is located downstream
of the compressor and functions to draw return air in a generally
lineal flow path across the evaporator coil and around the
compressor, for discharge in an axial direction thereby resulting
in a generally linear air flow path through the unit. A spiral
wound tubular refrigerant-to-water condenser is preferably disposed
surrounding relation with the axial flow supply fan thereby
minimizing space requirements. A cabinet is provided to enclose the
components thereby allowing for the installation of electric
heating elements. Enclosing the components within a cabinet avoids
the need to paint or otherwise coat the enclosed components thereby
reducing manufacturing costs.
[0017] A marine A/C unit in accordance with the present invention
significantly overcomes the limitations and disadvantages present
in the art. Locating the compressor between the evaporator coil and
supply fan creates increased separation between the evaporator coil
and supply fan inlet, as compared with prior art marine air
conditioners, such that even air flow across the evaporator coil is
achieved thereby eliminating evaporator coil icing. In order to
take full advantage of the available space, the present invention
relocates virtually all the refrigeration and electrical components
between the evaporator and the fan intake without significantly
interfering with airflow across the coil. In addition, providing
sufficient space between the evaporator coil and supply fan
eliminates localized high evaporator coil air flow velocities such
that water does not become entrained in the leaving air stream. The
use of an axial flow fan allows for the air to travel through the
unit in a generally linear air flow path thereby avoiding the
L-shaped flow paths associated with prior art devices. Mounting the
compressor in the interior of the unit, namely between the
evaporator coil and the supply fan, functions to significantly
reduce compressor noise propagation, and providing a cabinet
enclosure results in further noise reduction. Placement of the
compressor on the leaving air side of the evaporator coil causes
cold, approximately 58.degree. F., air to circulate around the
compressor thereby providing improved external cooling leading to
greater efficiency and longer compressor life. Finally, providing
the unit with a cabinet to enclose the various components not only
functions to reduce noise, but allows for the installation of
electric heating elements safely within the confines of the
housing.
[0018] Accordingly, it is an object of the present invention to
provide a compact marine air conditioning system that overcomes the
shortcomings of the prior art systems.
[0019] Another object of the present invention is to provide such a
system that is compact while maximizing the distance between the
evaporator coil and supply fan inlet.
[0020] Yet another object of the present invention is to provide
such a system configured with a generally linear air flow path.
[0021] Still another object of the present invention is to provide
such a system wherein the compressor is located downstream from the
evaporator coil so as to improve compressor performance and
reliability.
[0022] Another object of the present invention is to provide such
as system wherein the supply fan comprises an axial flow
configuration for maintaining a linear air flow path and supply air
discharge.
[0023] Yet another object of the present invention is to provide
such a system that is enclosed by a cabinet.
[0024] Still another object of the present invention is to provide
such a system capable of being equipped with electric heating
elements.
[0025] Another object is to provide a multi configuration marine
air conditioning unit that is very quiet, esthetically pleasing
since mechanical and electrical components are all enclosed,
preventing any damage of exposed components, thus making the unit
easier to manufacture because the compressor and related components
do not need to be painted.
[0026] In accordance with these and other objects, which will
become apparent hereinafter, the instant invention will now be
described with particular reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0027] Various other objects, features and attendant advantages of
the present invention will become fully appreciated as the same
becomes better understood when considered in conjunction with the
accompanying drawings, in which like reference characters designate
the same or similar parts throughout the several views, and
wherein:
[0028] FIGS. 1-3 depict a marine air conditioning unit in
accordance with the prior art;
[0029] FIG. 4 is a side view schematic diagram of a compact marine
air conditioning unit in accordance with the present invention;
[0030] FIG. 5 is a top view schematic thereof; and
[0031] FIG. 6 depicts an alternate embodiment including a supply
fan remotely mounted from the main unit.
DETAILED DESCRIPTION OF THE INVENTION
[0032] Turning now to the drawings, FIGS. 1-3 depict a
self-contained marine air conditioning unit in accordance with the
prior art as disclosed in U.S. Pat. No. 5,848,536, issued to Dodge
et al., referenced above. The Dodge A/C unit is generally
characterized as having an evaporator coil that functions to
transfer heat between refrigerant contained within the coil and
return air circulating across the coil. In an effort to minimize
unit size, an evaporator fan is mounted with an intake in close
proximity with the evaporator coil. In a further attempt to reduce
unit size a refrigerant-to-water heat exchanger, which functions as
a condenser, is mounted between the evaporator and the
blower/supply fan. Various other mechanical and electrical
components, including the compressor, and other mechanical and
electrical apparatus are mounted along side the evaporator coil. As
noted above, the placement of the supply fan inlet in close
proximity to the evaporator coil results in uneven airflow across
the evaporator coil, particularly at the coil edges and corners.
This uneven airflow is known to cause ice to form on the coil
thereby leading to coil freeze-up and resulting unit shut down. In
addition, since the compressor is not mounted in an air stream, the
Dodge unit relies exclusively on internal refrigerant flow to cool
the side-mounted compressor. It has been found that in warm
operating conditions the unit is prone to overheating, and in cold
operating conditions liquid refrigerant has been found to migrate
back to the compressor, both situations are present conditions that
lead to compressor failure. The blower discharge is angled upward
90-degrees relative to the return air stream thereby complicating
installation in a large number of vessels. Finally, the lack of a
cabinet to enclose the components exposes the unit to damage. In
addition, sales and marketing considerations mandate that the
components be painted, which significantly increases manufacturing
time and cost.
[0033] FIGS. 4-6 provide schematic illustrations of a compact
self-contained marine air conditioning system/unit, generally
referenced as 10, in accordance with the present invention. It
should be noted that all refrigerant lines are not shown to simply
the illustration. The routing of refrigerant lines between the
compressor, evaporator, and condenser, is considered within the
ordinary skill in the art, and may be accomplished in any of a
variety of configurations. Air conditioning unit 10 comprises a
water-cooled package marine air conditioning unit specifically
designed for installation on marine vessels. Marine air
conditioning unit 10 is preferably manufactured in various sizes
and tonnage capacities, including 1/2 ton (e.g. 6,000 BtuH), 1.0
ton, 11/2 ton, 2 ton, etc. Marine air conditioning unit 10 includes
an evaporator coil 20, a refrigerant compressor 30, a water-cooled
condenser 40, a supply fan 50, and a cabinet 60 for substantially
enclosing the components. Evaporator coil 20 preferably comprises a
fin and tube refrigerant-to-air heat exchanger as used in direct
expansion vapor compression refrigeration cycle units. Evaporator
coil 20 may be any suitable configuration, e.g. flat, L-shaped,
A-shaped, etc., and may further be disposed on any suitable side or
sides of the cabinet. Compressor 30 preferably comprises a
scroll-type refrigerant compressor of the type commonly used in
vapor compression refrigeration systems, however, any suitable
compressor is considered within the scope of the present invention.
Condenser 40 preferably comprises a generally tubular co-axial
water-to-refrigerant heat exchanger. Supply fan 50 preferably
comprises an axial flow fan that functions to discharge the cooled
air in a generally linear flow path, e.g. perpendicular to the
evaporator coil face. Accordingly, the present invention draws air
in from one direction and discharges the air from the other side in
the same direction. Cabinet 60 is preferably thermally insulated
and functions to substantially enclose evaporator 20, compressor
30, condenser 40, supply fan 50 (in a first embodiment), and
various electrical and control components, such as capacitors. In
addition, cabinet 60 further functions to enable marine air
conditioner 10 to be equipped with optional electric heating
elements, referenced as 70.
[0034] A number of significant advantages over prior art marine air
conditioning units are realized by a marine A/C unit in accordance
with the present invention. One advantage relates to eliminating
ice formation on the evaporator coil 20 by locating the compressor
30 between evaporator coil 20 and supply fan 50 so as to create
increased separation between evaporator coil 20 and the supply fan
inlet 52, as compared with prior art marine air conditioners, such
that even air flow across the evaporator coil is achieved. In
addition, maximizing the spacing between evaporator coil 20 and
supply fan 50 eliminates localized high evaporator coil air flow
velocities generated by the supply fan inlet such that water does
not become entrained in the leaving air stream. In order to take
full advantage of the available space, the present invention
locates virtually all the refrigeration and electrical components
between the evaporator and the fan intake without significantly
interfering with airflow across the coil. Accordingly, electrical
components, such as capacitors, contactors, resistors, etc. may be
mounted between the leaving air side of the evaporator coil and the
supply fan/blower inlet, which location is in the path wherein
conditioned (e.g. cooled) air circulates thereby helping to prevent
said electrical components from overheating.
[0035] A further significant advantage of the present invention
involves the use of an axial flow supply fan. More particularly,
the use of an axial flow supply fan allows for the air to travel
through the unit in a generally linear air flow path thereby
avoiding the L-shaped flow paths associated with prior art devices.
As a result air enters the evaporator and is discharged from the
unit in generally the same direction, e.g. along a linear flow path
from unit inlet to unit discharge. This feature is considered
particularly important when installing the unit on a marine vessel
wherein such units are often installed below seats, benches, and
bunks (e.g. beds) wherein the available space is typically long and
narrow. The shape of axial flow supply fan 50 further allows for
positioning of a water-to-refrigerant heat exchanger wound in
surrounding relation with fan 50. This configuration maximizes use
of the space and minimizes the overall size of the unit. In a
contemplated alternate embodiment, fan 50 may be remotely mounted
so as to allow for adaptable installation of one or more fans in
communication with the unit via air ducts.
[0036] In an alternate embodiment depicted in FIG. 6, supply 50 is
adapted for installation remote from the main unit and connected by
a duct 80. Duct 80 preferably comprises flexible tubular duct. The
embodiment depicted in FIG. 6, further minimizes the required
installation space for the main unit by replacing the unit mounted
supply fan shown in FIGS. 4 and 5, with a fan that may be mounted
in a suitable remote location, such as in a cabin. As best seen in
FIG. 6, the condenser coil 40 is configured in surrounding relation
with compressor 30. This configuration allows the condenser inlet
and outlet to project from cabinet 60 on the opposite side of
evaporator coil 20 (rather than from the side as depicted in the
embodiment shown in FIGS. 4 and 5), in a linear direction, e.g.
along the air flow path, thereby further facilitating installation
of the system within a long but narrow space.
[0037] Yet another significant advantage relates to improved
silencing. Mounting the compressor in the interior of an enclosed
unit, namely between the evaporator coil and the supply fan,
functions to significantly reduce compressor noise propagation, and
providing a cabinet enclosure results in further noise reduction.
More particularly, locating the compressor between the evaporator
fan the and evaporator coil allows the body of the compressor to
function as a sound barrier that prevents sound from propagating to
the surrounding environment through the evaporator coil.
[0038] Still another object of the present invention related to
compressor performance and reliability. Placement of the compressor
on the leaving air side of the evaporator coil causes cold,
approximately 58-degree, air to circulate around the compressor
thereby providing improved cooling leading to greater efficiency
and longer compressor life. This configuration results in a number
of significant advantages, namely, (1) reduced head pressure; (2)
increased sub-cooling; (3) increased cooling capacity; and (4)
increased dehumidification. More particularly, head pressure is
reduced by mounting the compressor crankcase in contact with the
cold air leaving the evaporator coil. This has the effect of
decreasing the condensing pressure of the refrigerant and makes the
system more efficient by increasing the net cooling capacity of the
system due to the increased mass flow of refrigerant through the
compressor. In addition, liquid sub-cooling is increased beyond
that which would be achieved with a remote mounted compressor (e.g.
one not exposed to evaporator coil leaving air) due to the
circulation of cold (approx. 58.degree. F.) air around the
compressor. The resulting increased liquid sub-cooling increases
gross cooling capacity due to lower enthalpy of the refrigerant
entering the evaporator. A further advantage realized beyond
increased cooling capacity is increased dehumidification due to the
increased gross sensible and latent (e.g. total) cooling capacity
resulting in lower evaporator coil leaving air temperature thereby
causing more moisture to be removed from the air stream. Maximizing
dehumidification is particularly important in marine air
conditioning applications due to the inherently high humidity
geographical locations frequented by marine vessels. Having the
compressor located within the conditioned air stream and on the
leaving air side of the evaporator coil functions to re-heat the
air, a process known to result in increased dehumidification.
Further, the provision of a housing 60 results in significant
manufacturing cost savings since the internal components need not
be painted as is demanded with A/C units that do not include a
cabinet or housing.
[0039] Similar efficiency advantages are realized by also placing
the condenser coil within the conditioned air stream on the leaving
air side of the evaporator coil. More particularly, head pressure
is reduced by having the compressor crankcase and high pressure
refrigerant hot gas and liquid in the outer tube of the water
cooled condenser coil in contact with the cold air leaving the
evaporator coil has the effect of increasing the efficiency of the
condenser coil, and decreases the condensing pressure of the
refrigerant. This also makes the air conditioner more efficient by
increasing the net cooling capacity of the air conditioner due to
the increased mass flow of refrigerant through the compressor. This
configuration further leads to increased sub-cooling since the
compressor crankcase and high pressure refrigerant hot gas and
liquid in contact with the cold air has the effect of increasing
the liquid sub-cooling beyond that which would normally be
achieved. As a result, the water cooled condenser coil is more
efficient with cold air being drawn across it as opposed to prior
art systems wherein the condenser coil is disposed in the ambient
environment. The effect of increasing the sub-cooling of the liquid
beyond which would normally be achieved increases the gross cooling
capacity of the air conditioner. This is due to the lower enthalpy
of the refrigerant entering the evaporator.
[0040] A further advantage realized by locating both the compressor
and condenser coil in the conditioned air stream is realized.
Because refrigerant gas is cooled by the air flowing over the
compressor and condenser, even if water is not flowing through the
condenser, a high pressure switch is not required to protect the
unit against pump failures.
[0041] Finally, providing the unit with a cabinet to enclose the
various components not only functions to reduce noise, but allows
for the installation of an electric heating coil, referenced as 70,
safely within the confines of the housing. Electric heat is an
ideal option for marine air conditioner since the use of reverse
cycle or heat pump units is not practical since such systems do not
function efficiently if at all with low water temperatures found in
cold water environments. Electric heat has been used in the past
but the units had to be much too large in order to satisfy UL
regulations that require a certain minimum distance between the
electric element and the fan to avoid creating a fire hazard. The
present invention overcomes this limitation by using the compressor
as a shield and distance creating structure to ensure a safe
distance between the fan and the electric heating element or heat
strip.
[0042] A further and inherent advantage of a marine air conditioner
in accordance with the present invention involves ease of
installation. As noted above, marine air conditioning units must
often be installed below seats, benches, and bunks (e.g. beds)
wherein the available space is typically long and narrow. Since
marine air conditioning systems of the prior art typically form a
90-degree angled flow path installation has proven difficult.
Accordingly, the linear/in-line flow path achieved by a marine air
conditioning unit in accordance with the present invention
simplifies installation by essentially conforming to commonly
available spaces.
[0043] As should be apparent, various advantages of the present
invention may be realized independently. In addition, features
disclosed herein may be used with straight cool or heat pump
systems, including water cooled an air cooled systems.
[0044] The instant invention has been shown and described herein in
what is considered to be the most practical and preferred
embodiment. It is recognized, however, that departures may be made
therefrom within the scope of the invention and that obvious
modifications will occur to a person skilled in the art.
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