U.S. patent application number 13/915246 was filed with the patent office on 2014-04-10 for method and apparatus for operating ducted fumehoods with increased energy efficiency.
The applicant listed for this patent is Fipak Research and Development Company. Invention is credited to Francois Hauville.
Application Number | 20140096546 13/915246 |
Document ID | / |
Family ID | 44060000 |
Filed Date | 2014-04-10 |
United States Patent
Application |
20140096546 |
Kind Code |
A1 |
Hauville; Francois |
April 10, 2014 |
METHOD AND APPARATUS FOR OPERATING DUCTED FUMEHOODS WITH INCREASED
ENERGY EFFICIENCY
Abstract
A method for operating a ducted fumehood with increased energy
efficiency, wherein the method comprises: passing exhaust air from
the ducted fumehood through a heat exchanger, and passing other air
through the heat exchanger, so as transfer heat content from the
exhaust air to the other air, or to transfer heat content from the
other air to the exhaust air, so as to temperature-condition the
other air.
Inventors: |
Hauville; Francois;
(Ipswich, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Fipak Research and Development Company |
Rowley |
MA |
US |
|
|
Family ID: |
44060000 |
Appl. No.: |
13/915246 |
Filed: |
June 11, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12949611 |
Nov 18, 2010 |
8460441 |
|
|
13915246 |
|
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|
61281592 |
Nov 19, 2009 |
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Current U.S.
Class: |
62/89 ; 165/56;
55/385.2; 62/79; 95/273 |
Current CPC
Class: |
Y02B 30/56 20130101;
F24F 12/006 20130101; F24F 7/04 20130101; B08B 15/023 20130101;
B01D 2279/35 20130101 |
Class at
Publication: |
62/89 ; 95/273;
55/385.2; 165/56; 62/79 |
International
Class: |
B08B 15/02 20060101
B08B015/02; F24F 7/04 20060101 F24F007/04 |
Claims
1. A method for operating a ducted fumehood with increased energy
efficiency, wherein the method comprises: passing exhaust air from
the ducted fumehood through a heat exchanger, and passing other air
through the heat exchanger, so as transfer heat content from the
exhaust air to the other air, or to transfer heat content from the
other air to the exhaust air, so as to temperature-condition the
other air.
2. A method according to claim 1 wherein the exhaust air from the
ducted fumehood is passed through a filter before it is introduced
into the heat exchanger as a filtered air line.
3. A method according to claim 2 wherein the other air comprises
fresh air introduced into a building containing the ducted fumehood
as a fresh air line.
4. A method according to claim 3 wherein the filtered air line and
the fresh air line pass through the heat exchanger but do not
communicate with one another.
5. A method according to claim 4 wherein the heat exchanger is
configured to permit the transfer of heat energy from the filtered
air line to the fresh air line and vice versa.
6. A method according to claim 3 wherein the heat exchanger
comprises a first heat exchanger element interposed in the airflow
of the filtered air line, and a second heat exchanger element
interposed in the airflow of the fresh air line, and further
wherein a fluid line connects the first heat exchanger element with
the second heat exchanger element.
7. A method according to claim 6 wherein the heat exchanger
comprises a heat pump, and further wherein the fluid line comprises
a refrigerant line filled with a refrigerant, and further
comprising a compressor for selectively compressing the
refrigerant.
8. A method according to claim 7 further comprising a reversing
valve disposed in the refrigerant line, such that the heat
exchanger comprises a reversible heat pump.
9. A method according to claim 8 wherein the reversible heat pump
extracts heat content from the filtered air line and adds that heat
content to the fresh air line by directing liquid refrigerant from
the first heat exchanger element toward the second heat exchanger
element.
10. A method according to claim 8 wherein the reversible heat pump
extracts heat content from the fresh air line and adds that heat
content to the filtered air line by directing liquid refrigerant
from the second heat exchanger element toward the first heat
exchanger element.
11. Apparatus for operating a ducted fumehood with increased energy
efficiency, wherein the apparatus comprises: a heat exchanger
configured to receive exhaust. air from the ducted fumehood, and to
receive other air, so as to transfer heat content from the exhaust
air to the other air, or to transfer heat content from the other
air to the exhaust air, so as to temperature-condition the other
air.
12. Apparatus according to claim 11 wherein the exhaust air from
the ducted fumehood is passed through a filter before it is
introduced into the heat exchanger as a filtered air line.
13. Apparatus according to claim 12 wherein the other air comprises
fresh air introduced into a building containing the ducted fumehood
as a fresh air line.
14. Apparatus according to claim 13 wherein the filtered air line
and the fresh air line pass through the heat exchanger but do not
communicate with one another.
15. Apparatus according to claim 14 wherein the heat exchanger is
configured to permit the transfer of heat energy from the filtered
air line to the fresh air line and vice versa.
16. Apparatus according to claim 13 wherein the heat exchanger
comprises a first heat exchanger element interposed in the airflow
of the filtered air line, and a second heat exchanger element
interposed in the airflow of the fresh air line, and further
wherein a fluid line connects the first heat exchanger element with
the second heat exchanger element.
17. Apparatus according to claim 16 wherein the heat exchanger
comprises a heat pump, and further wherein the fluid line comprises
a refrigerant line filled with a refrigerant, and further
comprising a compressor for selectively compressing the
refrigerant.
18. Apparatus according to claim 17 further comprising a reversing
valve disposed in the refrigerant line, such that the heat
exchanger comprises a reversible heat pump.
19. Apparatus according to claim 18 wherein the reversible heat
pump extracts heat content from the filtered air line and adds that
heat content to the fresh air line by directing liquid refrigerant
from the first heat exchanger element toward the second heat
exchanger element.
20. Apparatus according to claim 18 wherein the reversible heat
pump extracts heat content from the fresh air line and adds that
heat content to the filtered air line by directing liquid
refrigerant from the second heat exchanger element, toward the
first heat exchanger element.
21. A system comprising: a ducted fumehood; a heat exchanger
configured to receive exhaust air from the ducted fumehood, and to
receive other air, so as to transfer heat content from the exhaust
air to the other air, or to transfer heat content from the other
air to the exhaust air, so as to temperature-condition the other
air.
Description
REFERENCE TO PENDING PRIOR PATENT APPLICATION
[0001] This patent application claims benefit of pending prior U.S.
Provisional Patent Application Ser. No. 61/281,592, filed Nov. 19,
2009 by Francois Hauville for MODULAR FILTRATION ASSEMBLY
(Attorney's Docket No. FIPAK-11 PROV), which patent application is
hereby incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to air filtration systems in general,
and more particularly to air filtration systems for purging
hazardous substances from the air.
BACKGROUND OF THE INVENTION
[0003] Air filtration systems are used in many situations to purge
unwanted substances from the air. Such filtration systems generally
exist in a variety of forms, depending upon their function.
[0004] One type of air filtration system in common use, e.g., in
laboratories, comprises a fumehood. A fumehood is a protected
enclosure for isolating a benchtop workspace from the ambient air
of a laboratory, in order that dangerous substances may be handled
safely within the fumehood without endangering nearby
personnel.
[0005] Fumehoods may be ducted or ductless. With a ducted fumehood,
the exhaust air from the fumehood is directed into building
ductwork which leads to the outside atmosphere, with a filter being
disposed intermediate the ductwork between the fumehood and the
outside atmosphere. With a ductless fumehood, the exhaust air from
the fumehood is directed into a filter which is attached directly
to the fumehood, with the filter purging hazardous substances from
the exhaust air before the exhaust air is directed back into the
ambient air of the laboratory.
[0006] Ducted fumehoods offer certain advantages, e.g., multiple
fumehoods can be exhausted through a single filter, their fixed
location (a consequence of the fixed ductwork within a building)
make them easy to oversee and administer, etc. However, ducted
fumehoods also suffer from the disadvantage that the ambient air of
the laboratory is exhausted through the fumehood to the outside
atmosphere. As a result, heated air is lost from the laboratory
during the winter, and cooled air is lost from the laboratory
during the summer, thereby driving up energy costs. Ductless
fumehoods do not suffer from this disadvantage, since they return
the filtered exhaust air back to the ambient air of the laboratory.
However, ductless fumehoods suffer from the disadvantage that each
fumehood requires its own filter, which can complicate logistical
issues such as filter monitoring, filter replacement, etc.
[0007] The present invention is directed to ducted fumehoods, and
more particularly to a novel method and apparatus for operating
ducted fumehoods with increased energy efficiency.
SUMMARY OF THE INVENTION
[0008] The present invention provides a novel method and apparatus
for operating ducted fumehoods with increased energy efficiency.
More particularly, the present invention provides a novel method
and apparatus for transferring heat content between the exhaust air
of a fumehood and other air so as to temperature-condition that
other air.
[0009] In one preferred form of the invention, there is provided a
method for operating a ducted fumehood with increased energy
efficiency, wherein the method comprises:
[0010] passing exhaust air from the ducted fumehood through a heat
exchanger, and passing other air through the heat exchanger, so as
transfer heat content from the exhaust air to the other air, or to
transfer heat content from the other air to the exhaust air, so as
to temperature-condition the other air.
[0011] In another form of the invention, there is provided
apparatus for operating a ducted fumehood with increased energy
efficiency, wherein the apparatus comprises:
[0012] a heat exchanger configured to receive exhaust air from the
ducted fumehood, and to receive other air, so as to transfer heat
content from the exhaust air to the other air, or to transfer heat
content from the other air to the exhaust air, so as to
temperature-condition the other air.
[0013] And in another form of the invention, there is provided a
system comprising:
[0014] a ducted fumehood;
[0015] a heat exchanger configured to receive exhaust air from the
ducted fumehood, and to receive other air, so as to transfer heat
content from the exhaust air to the other air, or to transfer heat
content from the other air to the exhaust air, so as to
temperature-condition the other air.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] These and other objects and features of the present
invention will be more fully disclosed or rendered obvious by the
following detailed description of the preferred embodiments of the
invention, which is to be considered together with the accompanying
drawings wherein like numbers refer to like parts, and further
wherein:
[0017] FIG. 1 is a schematic view showing a ducted fumehood;
[0018] FIG. 2 is a schematic view showing, among other things, a
ducted fumehood, a rooftop filter, and ductwork. connecting the
ducted fumehood to the rooftop filter;
[0019] FIG. 3 is a schematic view showing the novel method and
apparatus of the present invention, wherein a heat exchanger is
used to transfer heat content between the exhaust air of a fumehood
and other air so as temperature-condition that other air, whereby
to temperature-condition the ambient air of the laboratory;
[0020] FIG. 4 is a schematic view showing details of a preferred
form of the system of FIG. 3;
[0021] FIG. 5 is a schematic view showing one preferred form of the
present invention, wherein the heat exchanger comprises a
reversible heat pump, and further wherein the reversible heat pump
is configured to recover heat from the exhaust air of the fumehood
and return the recovered heat to the ambient air of the laboratory;
and
[0022] FIG. 6 is a schematic view showing the same system as FIG.
5, except that the reversible heat pump is configured to transfer
heat content from other air to the exhaust air of the fumehood so
as to temperature-condition that other air, whereby to
temperature-condition the ambient air of the laboratory.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] Looking first at FIG. 1, there is shown a typical ducted
fumehood 5. Ducted fumehood 5 generally comprises an enclosed
workspace 10 accessed by a front door 15, with front door 15
engaging a sash 20 when the enclosed workspace is "sealed". An air
inlet 25 admits ambient air from the laboratory into enclosed
workspace 10, and an air outlet 30 removes exhaust air from
enclosed workspace 10. The exhaust air from air outlet 30 is passed
into ductwork 35, which in turn leads to a filter (not shown in
FIG. 1) where the exhaust air is filtered before being vented to
the outside atmosphere.
[0024] More particularly, and looking now at FIG. 2, the exhaust
air from ducted fumehood 5 is passed through ductwork 35 to a
filter 40, where the exhaust air is filtered to remove hazardous
substances from the exhaust air (thereby rendering the exhaust air
safe) before the exhaust air is vented to the outside atmosphere. A
suction fan 45 is provided downstream of filter 40 so as to draw
the exhaust air out of fumehood 5 and through filter 40. In
addition, an exhaust fan 50 (FIG. 1) is preferably also provided at
the air outlet 30 of fumehood 5 so as to ensure that the enclosed
workspace 10 of fumehood 5 is kept at a negative pressure
differential relative to the ambient. air of the laboratory, in
order to ensure that any air within the enclosed workspace passes
through filter 40 before being vented to the outside
atmosphere.
[0025] In a typical installation, ducted fumehood 5 is located in a
laboratory within a building, and filter 40 is disposed on the roof
55 (FIG. 2) of that building, with ductwork 35 connecting the
output of ducted fumehood 5 to the input of filter 40, and with the
output of filter 40 being vented to the outside atmosphere.
Furthermore, in a typical installation, a plurality of fumehoods 5
are connected to the rooftop filter 40; however, in the figures,
only one ducted fumehood 5 is shown connected to filter 40 in order
to simplify the description.
[0026] It will be appreciated that, in relatively temperate
climates, the room temperature of the laboratory (within which the
fumehood is disposed) will be fairly close to the temperature of
the outside atmosphere. In this situation, there will be relatively
little energy loss from venting the temperature-conditioned air of
the laboratory to the outside atmosphere and replacing the
temperature-conditioned air of the laboratory with the
non-temperature-conditioned air of the outside atmosphere.
[0027] However, in other climates, e.g., the continental United
States and Europe, there is often a substantial difference between
the temperature of the ambient air of the laboratory and the
temperature of the outside atmosphere. In this situation, there can
be a relatively significant energy loss from venting the
temperature-conditioned air of the laboratory to the outside
atmosphere and replacing the temperature-conditioned air of the
laboratory with the non-temperature-conditioned air of the outside
atmosphere.
[0028] By way of example but not limitation, in the continental
United States and Europe, during winter, the temperature of the
ambient air in the laboratory might be 22 degrees C. and the
temperature of the outside air might be 0 degrees C.
Correspondingly, during summer, the temperature of the air inside
the laboratory might be 22 degrees C. and the temperature of the
outside atmosphere might be 32 degrees C. In these circumstances,
venting the "conditioned" air from inside the laboratory to the
outside atmosphere can be highly energy inefficient, since
additional energy is required in order to "condition" the new air
(drawn from the outside atmosphere) before it is supplied to the
laboratory.
[0029] Thus, in winter, venting heated laboratory air to the
outside atmosphere "wastes" the heat content of the conditioned
laboratory air and, in summer, venting the cooled laboratory air to
the outside atmosphere "wastes" the "cool content" of the
conditioned laboratory air.
[0030] By way of example but not limitation, in the continental
United States and in Europe, it is common for each vented fumehood
to add approximately $6,000-$8,000 to the cost of temperature
conditioning (i.e., heating or cooling) the ambient air of the
laboratory.
[0031] The present invention provides an extremely efficient and
cost-effective means for transferring heat content between the
exhaust air of a fumehood and other air so as to
temperature-condition that other air.
[0032] More particularly, and looking now at FIG. 3, in accordance
with the present invention, a heat exchanger 100 is disposed
between the output of filter 40 and the input to suction fan 45,
i.e., before final venting of the exhaust air to the outside
atmosphere. More particularly, heat exchanger 100 comprises a
filtered air line 102 passing through the heat exchanger and a
fresh air line 103 also passing through the heat exchanger.
Filtered air line 102 and fresh air line 103 do not communicate
with one another, i.e., the contents of the filtered air line do
not mix with the contents of the fresh air line. However, filtered
air line 102 and fresh air line 103 do permit the transfer of heat
energy from one air line to the other air line.
[0033] More particularly, and still looking now at FIG. 3, filtered
air line 102 comprises a first input line 105 which is connected to
the output of filter 40, and a first output line 110 which is
connected to the input of suction fan 45. Fresh air line 103
comprises a second input line 115 which draws fresh air from the
outside atmosphere and a second output line 120 which supplies
fresh air to the interior of the building. A blower fan 125 is
connected to second input line 115 so as to draw fresh air into
second input; line 115 and blow it out second output line 120.
[0034] Heat exchanger 100 transfers heat content between the heat
exchanger's filtered air line 102 and the heat exchanger's fresh
air line 103 so as to temperature condition (i.e., either warm or
cool) the fresh air prior to introducing that fresh air into the
building. In other words, heat exchanger 100 transfers heat energy
between filtered air line 102 and fresh air line 103 so as to
reduce the temperature differential between filtered air line 102
and fresh air line 103, whereby to temperature-condition the
outside air before it is introduced into the laboratory.
[0035] As noted above, the heat exchanger's filtered air line 102
and the heat exchanger's fresh air line 103 do not communicate with
one another, i.e., the contents of the filtered air line do not mix
with the contents of the fresh air line. However, filtered air line
102 and fresh air line 103 do permit the transfer of heat energy
from one air line to the other air line. To this end, and looking
now at FIG. 4, in one form of the present invention, heat exchanger
100 preferably comprises a first heat exchanger element 130
interposed in the airflow of filtered air line 102, and a second
heat exchanger element 135 interposed in the airflow of fresh air
line 103, with first heat exchanger element 130 being connected to
second heat exchanger element 135 by means of a fluid line 140. In
this construction, first heat exchanger element 130 transfers heat
content between the heat exchanger's filtered air line 102 and the
heat exchanger's fresh air line 103, whereby to temperature
condition the fresh air before the fresh air enters the
building.
[0036] It should be noted that it is generally preferable to
position the heat exchanger after the filter, rather than before
the filter, so that harmful substances can be removed from the
exhaust air of the fumehood before those harmful substances reach
the heat exchanger. This will, protect the heat exchanger from any
damage that could occur due to contact with harmful substances
contained in the exhaust air. Thus it will be appreciated that the
filter will serve two purposes: first, to remove unwanted
substances from the exhaust air so that those unwanted substances
are not vented to the outside atmosphere, and second, to protect
the heat exchanger from contact with harmful substances.
[0037] In one preferred form of the present invention, heat.
exchanger 100 comprises a reversible heat pump 100A. More
particularly, and looking now at FIGS. 5 and 6, the reversible heat
pump 100A comprises the first heat exchanger element 130 disposed
in the airflow of filtered air line 102, and the second heat
exchanger element 135 disposed in the airflow of fresh air line
103. A compressor 145 circulates refrigerant through a refrigerant
line 140. More particularly, refrigerant line 140 passes by first
heat exchanger element 130 so as to exchange heat therewith and
passes by second heat exchanger element. 135 so as to exchange heat
therewith. The reversible heat pump 100A also comprises a reversing
valve 150 for reversing the flow of refrigerant through refrigerant
line 140. Reversible heat pump 100A preferably also comprises a
pair of thermal expansion valves 155 and a pair of bypass valves
160 in refrigerant line 140.
[0038] FIGS. 5 and 6 illustrate operation of the reversible heat
pump assembly 100A during heating and cooling modes,
respectively.
[0039] More particularly, in FIG. 5, reversing valve 150 is set to
extract heat content from the filtered air line 102 and transfer
that heat content to the fresh air line 103, whereby to heat fresh
air line 103.
[0040] In FIG. 6, reversing valve 150 is set to extract heat
content from fresh air line 103 and transfer that. heat content to
filtered air line 102, whereby to cool fresh air line 103.
[0041] Significantly, because the reversible heat pump 100A is
designed to transfer heat content to and from filtered air line
102, and because filtered air line 102 contains air which has a
temperature which is very close to room temperature, the reversible
heat pump is always working off air that is approximately 22
degrees C. This makes for very efficient energy recapture from the
filtered air line, and allows for the use of smaller and more
efficient reversible heat pumps. It is believed that as much as 90%
of the thermal energy in the filtered air line can be recaptured
through the use of a reversible heat pump.
Modifications
[0042] It is to be understood that the present invention is by no
means limited to the particular constructions herein disclosed
and/or shown in the drawings, but also comprises any modifications
or equivalents within the scope of the invention.
* * * * *