Note: Descriptions are shown in the official language in which they were submitted.
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RESERVOI:R TYPE WATER HEATIMG DEVICE
B~CKG~OUND OF THE INVENTION
This invention relates to a reservoir type water
heating device serving as a source of hot water supply used
wlth a central hot water supply system or a small-sized
central hot water system and more particularly to such a
device employing a combustion device as a heating source and
especially including an exhaust pipe for exhaust gases due
to the combustion.
In central hot water supply systems or small-sized
simple hot water supply systems (which supply hot water to
the bath, kitchen, washing stand etc. equipped in a single
house), the heating source therefor is formed of a reservoir '7r~
type water heating device adapted to be heated by a combustion
device. Also in water heating device of the type referred
to and including the exhaust pipe through which exhaust
gases resulting from the combustion effected by an associated r,
combustion device are exhausted outside thereaf, and
particularly with petroleum, for example, kerosene used as a
~u~ the combustion device includes frequently a gun type
burner.
In conventional reservoir type water heating
devices including the~gun type burner, the drum serving as a ~,
hot water reservoir is underlaid with a combustion chamber
through a heat transfer wall and the burner establishes a
flame within the combustion chamber to heat water in the
drum. Then a flue formed of a heat transfer material
communicates with th combustion chamber and extends centrally
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through the drum to exhaust gaseous combus-tion products to
the atmosphere. After the flame has automatically disappeared
in the combustion chamber due to the water in the drum
reaching a predetermined temperature, heat accumulated in ~;
the water dissipates from the heat -transfer wall and ~lue !j
to the atmosphere through the spontaneous convection.
Accordingly, the more an amount of hot water accumulated in
the drum the more an quantity of dissipated heat will be
resulting in an undesirable problem that an operation
eficiency decreases. In view of experiences encountered by
the applicants till now, it has been believed that this
problem has not been previously noticed by any expert and
therefore no countermeasure to solve it is not taken.
Accordingly, it is the principal object o~ the
present invention to prevent or suppress heat accumulated in
an amount of hot water within a hot water reservoir from
dissipating through a ~lue.
It is an object of the present invention to provide
a new and improved reservoir type water heating device
accomplish.ing the principal object as above described in the
preceding paragraph.
It is another object of the present invention to
improve an outer portion of a reservoir type water heating
device for preventing or suppressing the heat dissipation as
above described.
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SUMMARY OF THE INVENTION
The present invention provides a reservoir type
. ~ water heat device comprising, in combination, a closed
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end drums including a hot water reservoir formed therein to ,~,
accumulate an amount of hot water, the drum communicating J
with both a ~ater supply pipe and a hot water delivery pipe,
combustion means disposed outside of the hot water reservoir
includin~ a combustion chamber to heat water within the
reservoir through the drum and form gaseous combustion
products therein, and an exhaust passageway connected to the
combustion chamber to exhaust the gaseous combustion products
externally of the combustion chamber therethrough, the
exhaust passageway being disposed outside of the hot water
reservoir without extending through the latter.
In a preferred embodiment of the present invention,
the exhaust passageway may be in the form of a tube including
a transverse tube portion having one end portion located
outside of a space disposed directly under the drum and a
~longltudinal tube portion having one end~connected to the
other end of the transverse tube portion and the other end
communicatlng with the combustion chamber.
~ ~ In order to inorease the overall efficiency, a
;~ chimney may be vertically disposed outside of the drum so
that a lower end thereof is connected to the one end of the
transverse tube portion and the chimney includes an upper
end connected to a transversely disposed extension tilted
downward at a predetermined angle to the hori~ontal.
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BRIEF DESCRIPTION OF ~EIE DRAWINGS
The~present invention will become more readily
apparent from the following detailed description taken in
conjunction ith the accompanying drawings in w~ioh:
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Figure l is a longitudinal sectional view of a
¦ conventional reservoir type water heating device with parts
¦ illustrated in elevation;
¦ Figure 2 is a longitudinal sectional view of one
¦ embodimen-t according to the reservoir type water warming
¦ device of the present invention with parts illustrated in
¦ elevation; and
¦ Figure 3 is a view similar to Figure 2 but
iIlustrating a modification of the present invention.
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DESCRIPTION OF T~IE P:REFERRED EMBODIME~TS .
Referring now to Figure l of the drawings, there
is illustrated a conventional reservoir type water heating
device. The arrangement illustrated comprises a water drum
lO, a comubstion chamber 12 disposed on the lower portion of
the dxum and surrounded by a heat transfer wall 14 except ng
that a bottom surface thereof is formed of the bottom wall
of the drum. The drum lO is covered with a heat isolating
member 16 and a burner 18 is disposed outside of the lower
portion of the heat isolating member 16 to open in the
combustion chamber 12. The burner 18 is operative to
establish a flame within the combustlon chamber 12 to heat
an amount of water 20 filling the drum lO.
Then a flue 22 communicates with the combustion
chamber 12 and extends centrally through the drum 10. The
flue 22 serves as an exhaust pipe through which gaseous
combustion products formed in the combustion chamber 12 axe
exhausted to the atmosphere. The flue 22 performs also the
function of transferring heat from the gaseous combustion
products to the water 2Q disposed in the drum lQ.
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In operation, the water 20 is heated with the ~i
flame established within the combustion chambex 12 to 1
accumulate heat therein. When the heated water 2Q reaches a
predetermiend temperature, the flame is automatically .,
extinguished. After the extinguishment of the 1ame, heat
accumulated in the hot water 20 is transmitted through the
heat transfer wall 14 and the flue 22 wall and dissipated
from inner surfaces thereof due to the spontaneous convention
Therefoxe, the larger the amount of hot water disposed in
the drum 10 the more an quantity of heat dissipated from the
hot water will be resulting in an undesirable problem that
an operation efficiency decreases. In view Q~ experiences
encountered by the applicants till now, it has been believed
that this undesirable problem has not previously no-ticed by
any expert and therefore no countermeasure to solve it has
not been yet taken.
The quantity of dissipated heat as above described
may be expressed by
Q = aS~T and hT = tw - ta
where Q designates the quantity of dissipated heat in
Kcal/hr, a a convention heat transfer rate in Kcal/m2hrC, S a v;
convection heat transfer area in m , tw a temperature on a
heat transfer surface in C and ta designates the ambient
temperature in C.
In water heatin~ devices commonly marketed in ~i~
Japan the quantlty of dissipated heat Q has a value of 8 x
1. 1 x 70 -. 600 Kcal/hr, because ~, S and ~T have ~enerally s
values of 8 Kcal/m hrC, 1.1 m2 and 80 - 10 = 70C
respectively. 3
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Each home served with a simple central hot water- 71
supply system has usually a burden of hot water supply on f
the order of 20,Q00 Kcal a day which figure averages 1,500
Kcal/hr to twelve hours.~ Therefore it can be understood 7
that the quantity of dissipated heat as above calculated is
large as compared with the mean figure just specified.
Also comventional gun type burners are handy, on
the one side apd actually not so good in combustive property
as~well as being unavoidable to produce some amount of soot
; due to their destined diffusion combustion, on the other
hand. Further, with fIames caused from this difusion
combustion, the direct contact of the flames with an adjacent
cold heat transfer wall or the like has resulted ln one of
causes for sooting. This has led to the necessity of making
- ~ ~ the particular combustion chamber large by taking account of
~a sufficient margin. ~ ~
On the other hand, in order to increase an
efficiency of heat exhange, it~is re~uired to increase a
; Reynolds number of a heat transfer portion. This results in
the necesslty of increasing flow speeds of associated fluids
or to decrease a hydraulic diameter involved. However,
because of a fear that the heat transfer wall is sooted, the
. ~ ~ ~efficiency of heat exchange can not be so much increased and
~ ~usually ranges from a~out 60 to about 75~. Accordingly even
7~ with the quantity of dissipated heat in view, the actual
efficlency of operation is of about 50 to about 60~ resulting -¦
l in the waste of thermal energy.
; Referring now to Figure 2, there is illustrated a
reservoir type watcr~heating device according to th_ present
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invention. The arrangement illustrated comprises a vertically f.,
disposed metallic drum lO in the form of a hollow cylinder
including an upper end closed with an apertured dome-shaped
wall lOA and a lower end closed with a combustion chamber 12 :~
of generally crescent section to form a hot water reservoir
LQ~_therein. The combustion chamber 12 includes an upper
heat transfer wall l~ formed of any suitable metallic material
to be spherically convex toward the interior of the drum lO
with its periphery connected in watertight relationship with
the bo~tom of the drum and a lower metallic wall ln the form
of a truncated cone including a central aperture and a
periphery rigidly connected to the bottom of the drum lO. A
cylindrical burner 18 is coaxially disposed in the truncated
cone and opens in the central aperture on the lower wall of
the combustion chamber 12~to face a heated surface 14A
formed of the lower surface as viewed in Figure 2 of the
heat transfer wall 14. :
The lnterior of.the drum lO or reservoir lOB is
~illed with an amount of water to be heated or hot water ;~
deslgnated by the reference numeral 20 and -the outside of
the drum is surrounded by a well known heat insulating
material 16. As shown in Figure 2, a portion of the heat .
insulating material I6A surrounds in contact relationship
the outer peripheral wall of the drum lO, another portion f ~i
the heat insulating material 16B is disposed on the dome- :~
shaped wall lOA of the drum 10 and still another portion of
the heat insulating ma~terial 16C is suitably secured to the
lower surface of the lower wall of the combustion chamber 12
located bel the bottom of the drum.
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¦ The drum 10 is en
closed wi~hin a coaxial metal
¦ enclosure 24 with
a top cover to sandwich the portions o~
the heat insulati
ng material 16A and 16B therebetween. Then Z
a hot water deliv
ery pipe 26 is extendea and sealed through
the top enclosure
cover and to be snugly ~itted into an 1y
aperture on the d
ome-shaped drwm wall lOA while a water
sùpply pipe 28 is
extended and sealed through the enclosure
24 at its level s
ubstantially equal to that of the central
portion oP the com
bustion chamber 12 and then extended
through the adjac
ent part of the portion of the heat
insulating materi
al 16A until it opens ln the interior of
the drum 10.
In~this
way, the drum lO, the enclosure 24 and the
associated compone
nts are connected lnto a uni-tary structure
1~ and supported by a plurality of leg members 30 (only two of
which are illustrated) standing up on the foundation. Then
a hollow cylindrical casing 32 substantially equal in diameter
to the enclosure 24 is suitably connected to the bottom of
the enclosure 24 to define an upper space 34 occupied by the
combustion chamber 12 and the substantial portion of the
burner 18 and a lower space 36 overlaid with the space 34
along ith the upper heat transfer wall 14 and a bottom
plate ~ closing the lower end thereof. The bottom plate 38
I is located below the burner 18 to be spaced away from the
latter by a predetermined dis-tance.
The burner 18 is operatéd to burn a mixture of an
atomized liquid fuel formed through the vaporizatlon and the
primary air. The liquid fuel may comprise kerosene. To
thi, end, an electromagnetic pump 40 of the well known
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construction is disposed in the lower space 36 to be spaced
away from the burner 18 by a predetermined distance and ;~
connected to khe latter -through a fuel feed tube 42. A ~,
constant oil-level device 44 is disposed on the bottom plate f
38 and overlaid with the pump 40. The constant oil-level
device 44 is well known in the art and adapted to be supplied f
with a fuel from an external oil reservoir (not shown)
through a fuel supply pipe 44A extending throu~h the casing f
32. In order to supply the primary air or burning air to flf
the burner 18, a blower 46 is mounted to the ~ottom plate 38 il
and connected to the burner 18 through an air supply tube.
The blower 46 is also spaced away from the burner 18 by a
predetermined distance.
As the burner 18 is operative to stop the burning ~`
when the water 20 reaches~a predetermined temperature and to f
effect again the burning in response to the water decreasing
to another predetermined temperature lower than the 3
firstmentioned predetermined temperature. Components for
controlling the operation of the burner are also disposed if
within the lower space 36 although such components are not ~
illustrated. f
As shown in Figure 2, an exhaust passageway 48 in h
the form of a metallic tube includes a transverse tube f
portion horizontally disposed to extend parpendicularly
through the casing 32 and having one end portion disposed ff
outside of the space 36 ~ffUSt located below the drum 10. The '!
exhaust tube 48 also includes a longitudinal tube portion ~,
48A connected to the other end of the transverse tube portion f
and extending upward in the ~orm of a bend to open in the
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conical portion of the lower wall o~ -the combustion chamber
12 adjacent to the periphery thereof. The exhaust passageway
48 is encircled by an air feed passaqeway 50 in the form of ~,
a metalli tube to form an air annular passageway therebetween. ~?
The air feed tube 50 includes a closed encl adjacent to that
end of the exhaust`tube 48 opening in the combustion chamber
12 and communicates with the blower 46 on the suction side.
The air feed tube 50 also extends through the casing 32
while it forms a double tube structrure with the exhaust
tube 48.
Then the exhaust and feed passageways 48 and 50
respectively are connected to a combined feed and exhaust
duct 52 extending through an opening 54A disposed on a wall
54. More specifically, the exhaust passageway 48 is connected
to an inner tube portion 52~ of the duct 42 through an
extension 56 thereof while the air feed passageway 50 is
connected to an outer tube portion 52B encircling the inner
tube portion 52 through a connection tube 58 disposed to be
spaced away from the extension 56. The inner tube portion
52A serves to exhaust gaseous combustion products formed in
the combustion chamber 12 to the atmospher while the outer
tube portion 52B serves to suck the air to deliver it to the
blower.
From the foregoing it is seen that a combustion J~
device generally designated by the reference numeral 60 is
formed of the combustion chamber 18, the electromagnetic
pump 40, the constant oil-level device 44, the blower 46,
the exhaust passageway 48, the air feed passageway 50 etc.
and supported by the leg members 30 and the bo-ttom plate 38.
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In operation the burner 18 heats the amount of
water 20 in the reservoir lOB while gaseous combustion
products are exhausted through the exhaust tube 48 and the
associated components. When the water 20 reaches its prede- d
termined temperature, the burning is stopped at and after
which heat accumulatied in the water :is dissipated through
the heat transfer wall 12. However, since the exhaust tube
48 is lowered in level than the heat transfer wall 12, -the
convection causes no heat dissipation. In other words,
thermaI energy remains in the combustion chamber 12 without
escaping therefrom. Also the heat transfer wall 14 is
located at the bottom rather than the upper or peripheral
wall of the drum 10 while the water forms a temperature
boundary haviny a lo~ temperature in the lower portion of
the drum 1~ due to its convention. As a result, the heat
transfer wall is put at a low temperature and accordinglv a
temperature difference between the heat transfer wall 14 and
air within the combustion chamber 12 becomes small. This 3
results in a decrease in amount of dissipated heat. That
is, when the heat dissipation through the heat transfer wall
14 proceeds more, an amount of dissipated heat therethrough
is more decreased. This results in an increase in overall
efEiciency.
When the hot water 20 is delivered through the hot
water delivery pipe 36 and cold water automatically
replenishes the drum's interior ox hot water reservoir lOA,
through the water supply pipe 28 until the water 20 is
lowered to its predegermined temperature. At that time, the
combustion device 25 is initiated automatically to effect ,
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the burning to heat the water 20 as in the prior art practice.
Until the water reaches the predetermined temperature higher
than that just described.
The process as above described is repeated to
accumulate always the hot water 20 in -the reservoir ~ .
Figure 3 shows a modification of the presen-t
invention. The arrangement illustrated is diEferent from
that shown in Figure 2 only in that in Figure 3, a chimney
62 is connected to the exhaust tube 48 outside of the
enclosure 24. The chimney 62 with a relatively small diameter ll
includes a vertical portion 62A connected to the lower end
as viewed in Figure 3 of the exhaust tube 48 and a lateral
portion 62B connected to the upper end of the vertical
portion 62A to be tilted downward at an angle of five degrees
or more to~the horizontal. The lateral portion 62B extends 3
beyond the room to permit the gaseous combustion products to
be exhausted to the atmosphere. Further, the vertical
chimney portion 62A is provided on the lower end with a J
drain tube 64 for delivering drains formed in the chimney to J
the outside of the latter.
In the arrangement illustrated, the chimney 62 has
its inlet and outlet temperature small in difference there-
between with the result that a heat loss due to the convection
or draft become small. In additon, as the lateral chinmey
portion 62B is til-ted to the horizontal, drains and rain
water are prevented from being intruded into the interior of
the chimney 62.
From the foregoing it is seen that the prsent
invention provides a reservoir type water heating device
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having a high heat efficiency. For example, the embodiment ~.
shown in each of Figures 2. and 3 has a quan~ity of dissipated
heat of from 75 - lO0 Kcal/hr during no cumbusion, an
efficiency of heat exhcange of about 85% and an operation
efficiency of abou~ 80%.
While the present invention has been illustrated
and described in conjunction with a few preferred embodiments
thereof it is to be understood that numerous changes and
modifications may be resorted to without departing from the
s~ir t nd ~ ~e E th~ pr ~ t inveAt o .
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