U.S. patent application number 12/271896 was filed with the patent office on 2009-05-21 for duct mounted dehumidifier using parallel air flow.
This patent application is currently assigned to Dinh Research LLC. Invention is credited to Khanh Dinh.
Application Number | 20090126387 12/271896 |
Document ID | / |
Family ID | 40640535 |
Filed Date | 2009-05-21 |
United States Patent
Application |
20090126387 |
Kind Code |
A1 |
Dinh; Khanh |
May 21, 2009 |
Duct mounted dehumidifier using parallel air flow
Abstract
In one aspect, a dehumidifier is provided for installation in an
air duct of an HVAC system. The air duct has air flowing
therethrough controlled by a blower of the HVAC system. The
dehumidifier includes an enclosure, which includes a compressor
connected to an evaporator and a condenser. The evaporator has a
first air flow rate for the air flowing therethrough. The condenser
has a second air flow rate for the air flowing therethrough,
wherein the second air flow rate is higher than the first air flow
rate. In another aspect, the evaporator has a first air impingement
surface area for the air flowing therethrough. The condenser has a
second air impingement surface area for the air flowing
therethrough, wherein the air impingement surface area is larger
than the first air impingement surface area. Another aspect is
drawn to a system wherein a dehumidifier is installed in an air
duct.
Inventors: |
Dinh; Khanh; (Gainesville,
FL) |
Correspondence
Address: |
WESTMAN CHAMPLIN & KELLY, P.A.
SUITE 1400, 900 SECOND AVENUE SOUTH
MINNEAPOLIS
MN
55402
US
|
Assignee: |
Dinh Research LLC
Gainesville
FL
|
Family ID: |
40640535 |
Appl. No.: |
12/271896 |
Filed: |
November 16, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61003547 |
Nov 16, 2007 |
|
|
|
Current U.S.
Class: |
62/272 ;
62/498 |
Current CPC
Class: |
F24F 3/153 20130101 |
Class at
Publication: |
62/272 ;
62/498 |
International
Class: |
F25D 21/00 20060101
F25D021/00; F25B 1/00 20060101 F25B001/00 |
Claims
1. A dehumidifier for installation in an air duct of an HVAC
system, wherein the air duct has air flowing therethrough
controlled by a blower of the HVAC system, the dehumidifier
comprising: an enclosure configured for installation in the air
duct; a compressor; an evaporator connected to the compressor, the
evaporator having a first air flow rate for the air flowing
therethrough; and a condenser connected to the compressor, the
condenser having a second air flow rate for the air flowing
therethrough, the second air flow rate being higher than the first
air flow rate.
2. The dehumidifier of claim 1 wherein the evaporator and condenser
are arranged so that air flowing through the duct flows through
both the evaporator and condenser in parallel.
3. The dehumidifier of claim 1 further comprising a heat exchanger
connected to the evaporator.
4. The dehumidifier of claim 3 wherein the heat exchanger is an
air-to-air heat pipe heat exchanger.
5. The dehumidifier of claim 1 wherein the condenser is positioned
to accept outlet air from the evaporator.
6. A dehumidifier for installation in an air duct of an HVAC
system, wherein the air duct has air flowing therethrough
controlled by a blower of the HVAC system, the dehumidifier
comprising an enclosure comprising: an enclosure configured for
installation in the air duct; a compressor; an evaporator connected
to the compressor, the evaporator having a first air impingement
surface area for the air flowing therethrough; and a condenser
connected to the compressor, the condenser having a second air
impingement surface area for the air flowing therethrough, the
second air impingement surface area being larger than the first air
impingement surface area.
7. The dehumidifier of claim 6 wherein the evaporator and condenser
are arranged so that air flowing through the duct flows through
both the evaporator and condenser in parallel.
8. The dehumidifier of claim 6 further comprising a heat exchanger
connected to the evaporator.
9. The dehumidifier of claim 8 wherein the heat exchanger is an
air-to-air heat pipe heat exchanger.
11. A dehumidification system comprising: a blower of an HVAC
system; an air duct of the HVAC system, wherein the air duct has
air flowing therethrough controlled by the blower; a dehumidifier
enclosure installed in the air duct comprising: a compressor, an
evaporator connected to the compressor, the evaporator having a
first air rate for the air flowing therethrough; and a condenser
connected to the compressor, the condenser having a second air flow
rate for the air flowing therethrough, the second air flow rate
being higher than the first air flow rate.
12. The system of claim 11 wherein the evaporator and condenser are
arranged so that air flowing through the duct flows through both
the evaporator and condenser in parallel.
13. The system of claim 11 further comprising a heat exchanger
connected to the evaporator.
14. The system of claim 13 wherein the heat exchanger is an
air-to-air heat pipe heat exchanger.
15. The system of claim 11 wherein the condenser is positioned to
accept outlet air from the evaporator.
16. The system of claim 11 wherein the air duct is a return duct of
the HVAC system.
17. The system of claim 11 wherein the air duct is a supply duct of
the HVAC system.
18. The system of claim 11 wherein the air duct is a fresh air
supply duct of the HVAC system.
19. The system of claim 11 wherein the compressor operates only
when the blower operates.
20. The system of claim 11 wherein the evaporator is thicker than
the condenser.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from, and hereby
incorporates by reference, U.S. provisional application Ser. No.
61/003,547, filed Nov. 16, 2007, to Khanh Dinh, entitled "Duct
mounted parallel flow heat pipe dehumidifier."
BACKGROUND OF THE INVENTION
[0002] In modern buildings, control of humidity is needed for human
comfort, health, as well as for the preservation of items such as
books, paintings, and carpets, for example. In hot and humid
climates, the use of air conditioners is common to help reduce
indoor humidity, and people sometimes use their air conditioners
even when temperatures are mild, just to reduce humidity. Whole
house dehumidifiers based on the vapor compression cycle are now
available from several manufacturers, but most are stand alone
units that include their own compressor, blower, evaporator, and
condenser. These common machines include the Aprilaire model 1750,
for example. These units usually have limited air flow and
therefore are not effective for whole-house dehumidification.
[0003] Most vapor compression dehumidifiers are built based on the
general configuration shown on FIG. 1. The direction of air flow is
indicated by arrow F. A typical dehumidifier 10 includes an
evaporator/cooling coil/evaporating coil 12, a condenser/condensing
coil 14, a compressor 16 and a blower 18, all of which are enclosed
in an enclosure/cabinet 20. The air is drawn by blower 18 through
the evaporator 12, where water is condensed on the cold surface of
the evaporator 12 and removed from the dehumidifier 10 through
drain 22. The cold air exiting from the evaporator 12 is then used
to cool the condenser 14. The compressor 16 provides the vapor
compression motive power, and the blower 18 is used to draw air
through enclosure 20.
[0004] U.S. Pat. Nos. 4,607,498 and 5,404,938 by Dinh, hereby
incorporated by reference, teach that the dehumidification capacity
of the cooling coil can be increased by the use of an air-to-air
heat-exchanger such as a heat pipe. Such improved dehumidifiers 110
have been made commercially available by the Heat Pipe Technology,
Inc. of Gainesville, Fla., under the trade name of BKP.TM.
Dehumidifiers. Those improved dehumidifiers work based on the
principle shown in FIG. 2. Like in a conventional dehumidifier, air
is drawn through the different components of the dehumidifier
listed analogously as dehumidifier 110, evaporator 112, condenser
114, compressor 116, blower 118 enclosure 120, and drain 122, with
the addition of heat exchanger 124. Heat exchanger 124, by
exchanging heat between the incoming air and the air leaving
evaporator 112, pre-cools the air reaching evaporator 112, thereby
increasing the ability of evaporator 112 to remove moisture.
[0005] One difficult problem with integrating a dehumidifier into a
central air conditioning system is matching airflow requirements
for the dehumidifier and the central air conditioner. Typically, a
dehumidifier only uses 20% to 30% of the airflow that usually goes
through a central air conditioning system. For example, a
dehumidifier with a capacity of 100 pints per day typically uses
300 cubic feet per minute (cfm) of air, but a typical 3-ton central
air conditioning system in a house will require 1500 cfm.
[0006] One cannot successfully run all the air of a central air
conditioning system through a dehumidifier because such practice
would require too much blower energy, and the excess air will
reduce the ability of the dehumidifier to remove water. Therefore,
most dehumidifiers must have their own blower, and they are
typically installed in parallel with the air-handling portion of
the central air conditioning system, requiring complicated
duct-work, duct connections and dampers.
BRIEF SUMMARY
[0007] In one aspect, a dehumidifier is provided for installation
in an air duct of an HVAC system. The air duct has air flowing
therethrough controlled by a blower of the HVAC system. The
dehumidifier comprises an enclosure configured for installation in
the air duct. The dehumidifier further comprises a compressor
connected to an evaporator and a condenser. The evaporator has a
first air flow rate for the air flowing therethrough. The condenser
has a second air flow rate for the air flowing therethrough,
wherein the second air flow rate is higher than the first air flow
rate.
[0008] In another aspect, a dehumidifier is provided for
installation in an air duct of an HVAC system. The air duct has air
flowing therethrough controlled by a blower of the HVAC system. The
dehumidifier comprises an enclosure, which comprises a compressor
connected to an evaporator and a condenser. The evaporator has a
first air impingement surface area for the air flowing
therethrough. The condenser has a second air impingement surface
area for the air flowing therethrough, wherein the air impingement
surface area is larger than the first air impingement surface
area.
[0009] In yet another aspect, a dehumidification system comprises a
blower of an HVAC system that controls air flowing through an air
duct of the HVAC system. A dehumidifier is provided for
installation in the air duct. The dehumidifier comprises an
enclosure, which comprises a compressor connected to an evaporator
and a condenser. The evaporator has a first air flow rate for the
air flowing therethrough. The condenser has a second air flow rate
for the air flowing therethrough, wherein the second air flow rate
is higher than the first air flow rate.
[0010] This Summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description. This Summary is not intended to identify
key features or essential features of the claimed subject matter,
is not intended to describe each disclosed embodiment or every
implementation of the claimed subject matter, and is not intended
to be used as an aid in determining the scope of the claimed
subject matter. Many other novel advantages, features, and
relationships will become apparent as this description proceeds.
The figures and the description that follow more particularly
exemplify illustrative embodiments.
BRIEF DESCRIPTION OF THE FIGURES
[0011] The disclosed subject matter will be further explained with
reference to the attached figures, wherein like structure is
referred to by like reference numerals throughout the several
views.
[0012] FIG. 1 shows a conventional vapor compression
dehumidifier.
[0013] FIG. 2 shows an improved dehumidifier with an air-to-air
heat-exchanger.
[0014] FIG. 3 shows a duct mounted dehumidifier with separate
airflows serving the evaporator and the condenser in parallel, in
accordance with an exemplary embodiment of the present
disclosure.
[0015] FIG. 4 shows a modified configuration of FIG. 3, wherein a
portion of the condenser is located in the colder air stream
leaving the evaporator, for better sub-cooling of the liquid
refrigerant, in accordance with an exemplary embodiment of the
present disclosure.
[0016] FIG. 5. shows a modified embodiment of FIG. 3, wherein as
heat pipe heat exchanger is used to enhance the dehumidifier
capacity, in accordance with an exemplary embodiment of the present
disclosure.
[0017] While the above-identified figures set forth one or more
embodiments of the disclosed subject matter, other embodiments are
also contemplated, as noted in this disclosure. In all cases, this
disclosure presents the disclosed subject matter by way of
representation and not limitation. It should be understood that
numerous other modifications and embodiments can be devised by
those skilled in the art which fall within the scope and spirit of
the principles of this disclosure.
[0018] The figures may not be drawn to scale. Moreover, where
directional terms (such as above, over, left, right, under, below,
etc.) are used with respect to the illustrations or in the
discussion, they are used for ease of comprehension only and not as
limitations. The elements of the devices may be oriented otherwise,
as readily appreciated by those skilled in the art.
DETAILED DISCLOSURE
[0019] The present disclosure is directed to a vapor compression
dehumidifier that is added to the duct-work of a conventional
central air conditioning system. The dehumidifier is actually
installed in the main duct of the central air conditioning system
and receives the whole air volume used by the central air
conditioning. However, unlike conventional dehumidifiers, the
airflow does not go through the evaporator and then condenser in
series. Rather, the airflow is divided into parallel paths that
enter the evaporator and the condenser in parallel flows.
Typically, the air flow through the evaporator is the lesser one;
generally, the speed of air through the evaporator is slower so
that the air has the time to be cooled down to a low temperature,
insuring effective dehumidification by condensation of air-borne
water vapor. Typically, the airflow through the condenser is the
larger one, insuring effective cooling of the condenser for
efficient operation. The two airflows exiting the evaporator and
condenser then mix together and are directed to the conditioned
space.
[0020] The present disclosure is directed to a duct mounted, add-on
dehumidifier that uses the blower and air distribution ducts of a
central air conditioning system to dehumidify a whole house or
building. This innovation combines the two functions of cooling and
dehumidifying without conflict by creating parallel flows that
allow the large amount of air needed by the central air
conditioning system to go through a large area condenser coil and a
smaller air flow to go through the evaporator, allowing the
evaporator to lower the air temperature below the dew point and
effectively condense and remove moisture.
[0021] FIG. 1 shows a conventional vapor compression dehumidifier
10 that includes evaporator 12, condenser 14, compressor 16 and
blower 18, all of which are enclosed in a cabinet 20. In this
conventional dehumidifier 10, all the air goes through the
evaporator 12 first, then the condenser 14 second. The amount of
airflow is relatively small, and usually is a compromise to satisfy
both the requirements of the evaporator 12 and the condenser 14.
Such relatively small air volume is usually insufficient to
distribute over a whole house.
[0022] FIG. 2 shows an improved dehumidifier enhanced by a heat
pipe heat exchanger 124 installed in such fashion that the first
portion 124a of the heat exchanger 124 receives the incoming air,
from which it extracts heat and transfers such heat to the second
portion 124b of the heat exchanger 124, as taught by Dinh in U.S.
Pat. No. 5,404,938.
[0023] FIG. 3 shows a duct mounted dehumidifier with separate
airflows serving the evaporator and the condenser in parallel, in
accordance with an exemplary embodiment of the present disclosure.
In dehumidifier 210, mounted in duct 211 of a central air
conditioning system, evaporator 212 is smaller in size and
typically includes two or more rows of finned tubes 213; condenser
214 is larger in size and typically only includes one row of finned
tubes 215. Compressor 216 is connected to evaporator 212 and
condenser 214 with typical piping, metering devices, electrical
supply and controls to a vapor compression cycle.
[0024] Enclosure 220 contains evaporator 212 and condenser 214. In
an exemplary embodiment, enclosure 220 also contains compressor
216, though compressor 216 may alternatively be mounted outside
enclosure 220. Enclosure 220 is made to fit typical duct 211 sizes
found in central air conditioning systems and is installed in the
return duct or the supply duct of the central air conditioning
system. While we describe that enclosure 220 is installed "in" duct
211, it is to be understood that enclosure 220 need not be
completely contained within duct 211. Rather, by installing
enclosure 220 "in" duct 211, we mean that enclosure 220 is inserted
into the air flow path of duct 211. Drain 222 drains condensate
from dehumidifier 210.
[0025] All the air from the central air conditioning system goes
through enclosure 220, but only a small portion goes through
evaporator 212, with the larger remaining airflow going through
condenser 214. With the small amount of air going through
evaporator 212, the air temperature will drop down to a low point,
and moisture will be effectively condensed. On the other hand, the
large amount of air going through condenser 214 will insure
effective heat removal from the condenser 214 for efficient
operation. In exemplary embodiments, compressor 216 is installed in
various locations within enclosure 220. For example, compressor 216
may be installed on one side of the enclosure 220 or at the top or
at the bottom of enclosure 220. Compressor 216 typically does not
need to be in the air stream of the duct 211.
[0026] One important advantage of this innovation is that it will
allow optimization of the two airflows to maximize the operation of
both evaporator 212 and condenser 214 therefore maximizing the
efficiency of the dehumidifier 210. Air flow through air duct 211
is controlled by blower 226 of the HVAC system. Since the blower
226 of the central air conditioning system is used, there is no
need for a separate blower like in conventional dehumidifiers 10.
Since this innovative design is installed in the existing ductwork
211, there is no need for additional ductwork, ductwork connections
or dampers. Duct 211 may be an HVAC (heating, ventilation and
air-conditioning) supply duct, return duct, or fresh-air supply
duct, for example. An A-coil evaporator 228 of the central air
conditioning system is also shown. In an exemplary embodiment,
dehumidifier 210 operates only when blower 226 of the central air
conditioner operates.
[0027] FIG. 4 shows a modified configuration of FIG. 3, wherein a
portion of the condenser 314 is located in the colder air stream
leaving the evaporator 312, for better sub-cooling of the liquid
refrigerant, in accordance with an exemplary embodiment of the
present disclosure. Thus, condenser 314 is positioned to accept
outlet air from evaporator 312. In dehumidifier 310, mounted in
duct 311 of a central air conditioning system, evaporator 312 is
smaller in size and typically includes two or more rows of finned
tubes 313; condenser 314 is larger in size and typically only
includes one row of finned tubes 315. Compressor 316 is connected
to evaporator 312 and condenser 314 with typical piping, metering
devices, electrical supply and controls to a vapor compression
cycle. Enclosure 320 is made to fit typical duct 311 sizes found in
central air conditioning systems and is installed in the return
duct or the supply duct of the central air conditioning system.
Drain 322 drains condensate from dehumidifier 310.
[0028] FIG. 5 shows a modified embodiment of FIG. 3, wherein
air-to-air heat-exchanger 424 such as a heat pipe heat exchanger is
used to enhance the dehumidification capacity, in accordance with
an exemplary embodiment of the present disclosure. In dehumidifier
410, mounted in duct 411 of a central air conditioning system,
evaporator 412 is smaller in size and typically includes two or
more rows of finned tubes 413; condenser 414 is larger in size and
typically only includes one row of finned tubes 415. Compressor 416
is connected to evaporator 412 and condenser 414 with typical
piping, metering devices, electrical supply and controls to a vapor
compression cycle. Enclosure 420 is made to fit typical duct 411
sizes found in central air conditioning systems and is installed in
the return duct or the supply duct of the central air conditioning
system. Drain 422 drains condensate from dehumidifier 410.
[0029] Heat exchanger 424, by exchanging heat between the incoming
air and the air leaving evaporator 412, pre-cools the air reaching
evaporator 412, thereby increasing the ability of evaporator 412 to
remove moisture. Heat pipe heat exchanger 424 is installed in such
fashion that the first portion 424a of the heat exchanger 424
receives the incoming air, from which it extracts heat and
transfers such heat to the second portion 424b of the heat
exchanger 424, as taught by Dinh in U.S. Pat. No. 5,404,938.
[0030] In the illustrated embodiments, the ratio of air flows
between evaporator 212, 312, 412 and condenser 214, 314, 414 can
vary dramatically depending on the building environment, the
central air conditioning system, and the desired climate control
result. In some embodiments, the air flow rate through condenser
214, 314, 414 is more than twice the air flow rate through
evaporator 212, 312, 412. In an exemplary embodiment, the air flow
rate through condenser 214, 314, 414 is about three times the air
flow rate through evaporator 212, 312, 412. In other embodiments,
the air flow rate through condenser 214, 314, 414 is more than
three times the air flow rate through evaporator 212, 312, 412.
[0031] In many applications, it is generally desirable to have the
air flow ratio between the condenser 214, 314, 414 and the
evaporator 212, 312, 412 as large as possible. However, in some
applications, the air flow to the evaporator 212, 312, 412 should
be sufficient to prevent freezing on the evaporator coils. In other
cases, freezing on the evaporator coils is fine, as long as they
are periodically defrosted.
[0032] In an exemplary embodiment, the difference is air flow rates
through condenser 214, 314, 414 and evaporator 212, 312, 412 is due
primarily to the air resistance in the duct 211, 311, 411 at
condenser 214, 314, 414 and evaporator 212, 312, 412. The air
resistance is affected by factors such as the air impingement
surface area, thickness, and other design factors of the evaporator
212, 312, 412 and condenser 214, 314, 414 units and the physical
arrangement, placement, and sizing of the finned tubes 213, 215,
313, 315, 413, 415, for example. In one exemplary embodiment, the
finned tubes 213, 313, 413 are arranged in multiple rows to
maintain the same surface area of tubing within a smaller air
impingement surface area. In such a design, the thicker,
multi-layered design of finned tubes 213, 313, 413 results in more
air resistance, and thus slower airflow, through evaporator 212,
312, 412 compared to condenser 214, 314, 414. In another exemplary
embodiment, condenser 214, 314, 414 has a larger air impingement
surface than evaporator 212, 312, 412.
[0033] All patents, patent applications, provisional applications,
and publications referred to or cited herein are incorporated by
reference in their entirety, including all figures and tables, to
the extent they are not inconsistent with the explicit teachings of
this specification.
[0034] It should be understood that the examples and embodiments
described herein are for illustrative purposes only and that
various modifications or changes in light thereof will be suggested
to persons skilled in the art and are to be included within the
spirit and purview of this application.
* * * * *