U.S. patent number 3,798,920 [Application Number 05/303,179] was granted by the patent office on 1974-03-26 for air conditioning system with provision for reheating.
This patent grant is currently assigned to Carrier Corporation. Invention is credited to Robert D. Morgan.
United States Patent |
3,798,920 |
Morgan |
March 26, 1974 |
AIR CONDITIONING SYSTEM WITH PROVISION FOR REHEATING
Abstract
An air conditioning system including a refrigeration unit
comprising a compressor, a condenser, thermal expansion means and
an evaporator are connected together to form a closed circuit. A
reheat coil is provided downstream of the evaporator and upstream
of the space being conditioned by the system. When reheat is
required, a mixture of vaporous and liquid refrigerant is supplied
to the reheat coil to pass in heat transfer relation with the
conditioned air being supplied to the space so as to reheat the air
subsequent to its having been cooled and dehumidified by passing in
heat transfer relation with refrigerant flowing through the
evaporator. Dehumidified air is provided at a temperature level
that will not cause the space to be overcooled.
Inventors: |
Morgan; Robert D. (Syracuse,
NY) |
Assignee: |
Carrier Corporation (Syracuse,
NY)
|
Family
ID: |
23170867 |
Appl.
No.: |
05/303,179 |
Filed: |
November 2, 1972 |
Current U.S.
Class: |
62/173;
62/90 |
Current CPC
Class: |
F24F
5/001 (20130101); F24F 3/153 (20130101); F24F
3/1405 (20130101) |
Current International
Class: |
F24F
3/14 (20060101); F24F 5/00 (20060101); F24F
3/12 (20060101); F25b 029/00 () |
Field of
Search: |
;62/90,173,428,429 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wye; William J.
Attorney, Agent or Firm: Deutsch; Barry E.
Claims
I claim:
1. In an air conditioning system for providing cooled and
dehumidified air to a space to be conditioned, a refrigeration unit
comprising a compressor, a condenser, thermal expansion means, and
an evaporator connected together in a closed circuit and having
liquid refrigerant flowing in a first portion thereof, and vaporous
refrigerant flowing in a second portion thereof, the improvement
comprising:
A. means to pass a relatively cold heat exchange medium in heat
transfer relation with vaporous refrigerant flowing through said
condenser from said compressor, said heat exchange medium absorbing
heat from said vaporous refrigerant to condense the
refrigerant;
B. means to pass relatively warm air to be conditioned, for
subsequent discharge into said space, in heat transfer relation
with liquid refrigerant flowing through said evaporator, the
refrigerant absorbing heat from said air, the air being cooled
thereby;
C. heat exchange means disposed in the path of flow of said cooled
air downstream of said evaporator and upstream from said space;
D. bypass means about said condenser to pass at least a portion of
said vaporous refrigerant discharged from said compressor about
said condenser;
E. first valve means operably associated with said bypass means and
having first and second operating positions, said valve means in
its first position passing vaporous refrigerant about said
condenser to mix with liquid refrigerant flowing therefrom and in
its second operating position passing all the vaporous refrigerant
discharged from the compressor through said condenser;
F. second valve means disposed between said condenser and said
evaporator and having first and second operating positions, said
valve means when in its first operating position directing the
refrigerant through said heat exchange means and thence through
said evaporator and when in its second operating position directing
the refrigerant about the heat exchange means and directly to the
evaporator; and
G. control means operable to place said first valve means in its
first operating position and said second valve means in its first
operating position when dehumidified air is solely required in said
space and being further operable to place said first and second
valve means in their second operating positions when cooled and
dehumidified air is required in said space.
2. An air conditioning system in accordance with claim 1 wherein
said bypass means includes regulating means to control the amount
of vaporous refrigerant in said mixture of vaporous and liquid
refrigerant.
Description
BACKGROUND OF THE INVENTION
This invention relates to air conditioning systems operable to
provide relatively cool and dehumidified air to a space being
conditioned. In particular, this invention relates to such a system
having a reheat coil provided therein and being solely operable to
provide dehumidified air to the space when the temperature level in
such space does not require cooling, but the humidity level therein
requires dehumidified air.
It has now been recognized that maintaining comfortable conditions
within a space or room adapted for human occupancy requires not
only that the temperature of the air be controlled, but, in
addition thereto, the moisture content or humidity of the air be
similarly controlled. Many internal environments or spaces
typically have air conditioning systems which provide conditioned
air to regulate the temperature of the space. When relatively cool
air is provided to the space, not only is the temperature level
therein reduced but, in addition, the humidity level is also
lowered since the removal of heat from air will dehumidify the same
by lowering the air's dew point.
However, there are many times when the temperature level in the
room or space does not require cooling, albeit human discomfort may
still be experienced due to a relatively high humidity level within
such space. Such temperature generally falls within the range of
70.degree. to 75.degree.F. If cool air were to be provided to
dehumidify the space, uncomfortably cool temperatures would be
obtained, thereby causing discomfort to the occupants.
In the past, it has been proposed to cool the air in a conventional
manner and then reheat the same prior to its being supplied to the
space. The cooling of the air will remove the moisture or
dehumidify the same and the reheating of the air will raise the
temperature thereof so the space will not be overcooled. Examples
of prior art illustrating air conditioning systems having reheat
capabilities are disclosed in U.S. Pat. Nos. 2,515,842; 2,679,142;
and 2,940,281. Each of the arrangements disclosed in the cited
patents suffer from a common failure.
When reheating is required, vaporous refrigerant is provided to a
heat exchange coil functioning as a reheat coil. The ambient air
which has been cooled and dehumidified by passing in heat transfer
relation with refrigerant flowing through the evaporator of the
refrigeration unit is thence passed in heat transfer relation with
the vaporous refrigerant flowing through the reheat coil. The air
is thus warmed prior to its delivery to the space. However, as
noted hereinbefore, the temperature conditions at which solely
dehumidified air is required generally falls within the range of
70.degree. to 75.degree.F. Therefore, by passing the cooled and
dehumidified air in heat transfer relation with vaporous
refrigerant, the air has generally been reheated to an excessively
high level, thus elevating the temperature in the space to an
uncomfortable level. In addition, the vaporous refrigerant supplied
to the reheat coil has generally been unregulated. As is obvious,
the prior art defects caused such reheat systems to be generally
unsatisfactory.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to reheat conditioned
air to acceptable levels without overheating the same.
It is a further object of this invention to discharge conditioned
air into a space that requires solely dehumidified air without
overheating such space.
It is a further object of this invention to provide an air
conditioning system having a conventional refrigeration unit
operable to supply solely dehumidified air when the space being
conditioned requires dehumidification, without lowering or raising
the temperature in such space to an unacceptable level.
These and other objects of the present invention are obtained by
providing an air conditioning system including a refrigeration unit
having a heat exchange coil provided in the path of flow of the
conditioned air downstream from the evaporator and upstream from
the space being conditioned. When the humidity in the space is at
an uncomfortable level and the temperature in such space does not
require cooling, a mixture of vaporous and liquid refrigerant is
passed through the heat exchange coil.
Ambient air, which has been cooled and dehumidified by passing in
heat transfer relation with refrigerant flowing through the
evaporator is thence passed in heat transfer relation with the
mixture of vaporous and liquid refrigerant flowing through the
coil. The relatively cold air absorbs heat from the vaporous
refrigerant and thereby condenses the same. Regulating means is
provided to regulate the quantity of vaporous refrigerant supplied
to form the mixture of vaporous and liquid refrigerant. Thus,
dehumidified air may be supplied to a space when such space solely
requires dehumidified air, without overheating the space.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of an air conditioning system
embodying the present invention; and
FIG. 2 illustrates a control arrangement which may be employed with
the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawing and in particular to FIG. 1 thereof, there
is schematically shown a preferred embodiment of the present
invention. An air conditioning system 10 employing a refrigeration
unit incorporating the reheat means of the present invention is
illustrated. The refrigeration unit may be of a type typically
utilized in "split systems," that is air conditioning systems
having the evaporator coil disposed in the furnace or supply duct
and the condenser and compressor mounted outside of or remote from
the space being conditioned.
An outdoor heat exchange coil or condenser 16 is connected by means
of line 14 to the discharge side of a suitable refrigeration
compression mechanism, for example a reciprocating type compressor
12. The gaseous refrigerant produced in compressor 12 flows to
condenser 16 and is condensed by ambient air routed over the
surface of the condenser by an outdoor fan 20 which is suitably
connected to a motor or other prime mover 18. Liquid refrigerant
formed in condenser 16 flows via line 22, thermal expansion valve
32 and line 28 to indoor heat exchange coil or evaporator 42. It is
understood that other suitable expansion devices, such as a
capillary tube, may be employed in place of expansion valve 32.
Liquid refrigerant in evaporator 42 is converted to vaporous
refrigerant as it extracts heat from the medium, for example, air
passed over its surface by fan 40 which is suitably connected to a
prime mover such as electric motor 38. The cooled air is discharged
into the area being conditioned through a suitable outlet (not
shown). Vaporous refrigerant from evaporator 42 flows via line 46
to compressor 12 to complete the refrigerant flow cycle. The
foregoing describes a refrigeration unit of the conventional type
employed in air conditioning systems as is well known to those
skilled in the art.
A conduit 24 having first solenoid valve 26 and throttle valve 27
disposed therein connects line 14 to line 22. A second solenoid
valve 30 is disposed in line 28. The manner in which valves 26 and
30 are controlled shall be described in detail hereinafter.
A second heat transfer coil 44 is provided in the path of flow of
the conditioned air being discharged into the space or room in the
enclosure. Preferably coil 44 is disposed in the path of
conditioned air flow downstream of evaporator 42. Branch line 23
connects line 22 with the inlet to heat exchange coil 44. A line 36
connects the outlet from heat exchange coil 44 to line 28. Line 36
has a check valve 34 disposed therein. The check valve only permits
the refrigerant to flow from coil 44 through line 36 and thence
into line 28.
Referring now to FIG. 2, a preferred form of control, suitable for
use with the air conditioning system hereinabove described, is
schematically shown. A suitable source of electric power,
represented by lines L1 and L2, is connected to primary winding 52
of transformer 48. It is understood, a polyphase source of electric
power may be employed if the circuit is suitably modified.
A secondary winding 50 of transformer 48 is connected to first
control relay 58 and second control relay 60. The first and second
relays are connected in parallel with each other. Connected in
series with relays 58 and 60 is a temperature responsive switch 54.
Switch 54 is movable between terminals 55 and 59 for a reason to be
more fully explained hereinafter. Connected in series with second
relay 60 is a humidity responsive switch 56. Switch 56 in a closed
position contacts terminal 57. Terminals 55 and 57 are in parallel
with each other. When either terminal 55 or 57 has switch 54 or 56
respectively in contact therewith, control relay 60 is energized.
Control relay 58 is energized when switch 54 is moved into contact
with terminal 59.
When relay 60 is energized, switches 62, 64, and 65 operatively
connected thereto are closed. The closure of switch 62 energizes
motor 38 which thereby causes fan 40 to route air over coil 42. The
closure of switch 64 energizes motor 18, thereby causing fan 20 to
route outdoor air over condenser 16. The closure of switch 65
energizes motor 11 which is operatively connected to compressor
12.
Operatively connected to first relay 58 is a switch 66. The
deenergization of relay 58 causes switch 66 to contact terminal 68.
Terminal 68 is in series with solenoid valve 30. When switch 66
contacts terminal 68, the solenoid is energized so that valve 30 is
placed in an open position. The energization of control relay 58
causes switch 66 to disengage from terminal 68 and to engage
terminal 70. When switch 66 contacts terminal 70, solenoid valve 26
is energized to an open position. When switch 66 disengages from
terminal 68, valve 30 is placed in a normally closed position.
The manner in which the present invention functions to provide
dehumidified air without overcooling or overheating the area or
space being conditioned shall now be explained.
Assume the space being conditioned requires cooled and dehumidified
air. Temperature responsive switch 54 senses the requirement for
cooled air and moves so it engages terminal 55 in the manner
illustrated in FIG. 2. Control relay 60 is thus energized. Control
relay 58 remains deenergized since switch 54 is disengaged from
terminal 59.
When control relay 60 is energized, switches 62, 64, and 65 close,
thereby energizing motors 38, 18, and 11 respectively.
With control relay 58 in its deenergized state, switch 66 remains
in contact with terminal 68. Solenoid valve 30 is thus energized
into its open position. Since switch 66 is disengaged from terminal
70, solenoid valve 26 remains deenergized and in a closed
condition. Refrigerant flow through line 24 is thus prevented.
Thus, all of the refrigerant discharged from compressor 12 passes
through condenser coil 16.
As solenoid valve 30 is energized, the liquid refrigerant flowing
through line 22 is directed through line 28 to evaporator coil 42.
Check valve 34 prevents any of the refrigerant from flowing into
heat exchange coil 44. The refrigerant passing through coil 44
passes in heat transfer relation with ambient air, absorbing heat
from such air and becoming vaporous. The cooled air is then
delivered to the area or space requiring the same.
Assume now cooled air is no longer required in the area, but
dehumidified air is still needed to obtain comfortable
environmental conditions for the human occupants thereof. As noted
before, if the supply of cooled air were to be continued,
uncomfortable conditions would be created by the resultant
overcooling of such space.
Temperature responsive switch 54 will disengage from terminal 55
and move into contact with terminal 59 when cooling is no longer
required in the space. However, since the humidity level in such
space is still above a desired value, switch 56 remains in contact
with terminal 57; thus control relay 60 remains energized. Control
relay 58 is also energized since switch 54 now contacts terminal
59.
The energization of control relay 58 causes switch 66 to become
disengaged from terminal 68 and engaged with terminal 70. Solenoid
valve 30, in series with terminal 68, thereby becomes deenergized
and the valve moves to a normally closed position. Simultaneously,
solenoid valve 26, which is in series with closed terminal 70,
becomes energized and thereby moves into an open condition, thus
permitting vaporous refrigerant to flow from line 14 to line 22
about condenser coil 16. Throttle valve 27 provides a restriction
in line 24 to regulate the amount of vaporous refrigerant flowing
through line 24 and simultaneously the amount of refrigerant
passing through the condenser. Valve 27 may be manually or
automatically operated; if automatically operated, the valve will
regulate flow in accordance with temperature conditions in the
space. As an alternative, since the operating conditions at which
solely dehumidified air is required is generally from
70.degree.-75.degree.F, a suitably sized orifice may be provided as
an integral part of solenoid valve 26. A mixture of vaporous and
liquid refrigerant is thereby obtained in line 22.
Since valve 30 is closed, the mixture of vaporous and liquid
refrigerant passes from line 22 through line 23 and thence into
heat exchange coil 44. The refrigerant mixture exits from heat
exchange coil 44 and then passes via line 36 and expansion valve 32
into evaporator coil 42. Fan 40 operates in the conventional manner
to pass air to be conditioned over coil 42 where the refrigerant
passing therethrough absorbs heat from the air. The temperature of
the air is thus reduced so that its ability to hold moisture is
also reduced. Thus, cooled and dehumidified air is provided.
The cooled and dehumidified air is passed in heat transfer relation
with coil 44 having the mixture of vaporous and liquid refrigerant
passing therethrough. The air passing thereover absorbs heat from
the mixture of vaporous and liquid refrigerant, thereby condensing
the vaporous component of such refrigerant mixture and being warmed
thereby. The air is subsequently supplied to the area or space
being conditioned.
By passing the air in heat transfer relation with the mixture of
liquid and vaporous refrigerant, the dehumidified air is reheated
to a satisfactory temperature level.
By employing a mixture of liquid and vaporous refrigerant to reheat
the air prior to its being discharged into the space being
conditioned, the temperature of such conditioned air is neither
below a satisfactory temperature level, nor above the same, so that
desired temperature and humidity conditions may be readily obtained
in the space.
It should be particularly understood that the position of the heat
exchange coil relative to the evaporator may be altered without
departing from the spirit and scope of this invention. For example,
the reheat coil and evaporator may be arranged so that only a
portion of the total ambient air being conditioned will pass over
each heat exchange element. The separate air streams will thence be
mixed together prior to their delivery into the space. Other
variations that might readily occur to one skilled in the art may
also be employed.
While I have described and illustrated a preferred embodiment of my
invention, my invention should not be limited thereto, but may be
otherwise embodied within the scope of the following claims.
* * * * *