Note: Descriptions are shown in the official language in which they were submitted.
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.
HEATING APPAI~a~U~ ~iND METHOD
FOR OPE~A~ION T~R~OF
s
Heating appliances with an improved ef~iciency (IE)
and high efficiency (HE) are in large scale use in the
Netherlands and elsewhere for heating dwellings and other
accommodation areas. For many dwellings it is important
that such heating appliances take the most compact
possible form, while it must be avoided that the
appliances are so complicated that regular, costly
servicing and maintenance has to take place.
These known heating appliances have a number o~
drawbac~s, a number of significant ones being: the size
of the appliances, whereby they are difficult to build
into a cupboard or the li~e; the emission of CO and NOX as
well as the associated efficiency ].0s5, for instance
because considerable temperature differences are present
inside the apparatus.
The present invent-ion provides an apparatus for
heating fluid, comprising:
- first supply means for supplying fuel;
- second supply means for supplying oxidizing agent;
- burner means for combusting fuel and oxidizing
agents after mixing thereof; and
- a first heat exchanger to be heated by flue gases
of the burner means and arranged helically round the
burner means.
A heating appliance is obtained with the present
invention which can be embodied compactly and wherein
emissions and efficiency loss are limited.
Preferred embodiments of the apparatus relate to
further improvements in efficiency and reduction in
emission of undesired combustion products by precise
guiding of the combustion products along the heat
exchanger.
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- A jacket provided with openings i5 preferably
arranged round the helical heat exchanger in order to
enable a good heat exchange between the combustion gases
and the pipes of the heat exchanger. These openings can
be round or ~lot-shaped and are preferably arranged
behind the helically running pipe of the heat exchanger.
The jacket may also be formed from wound strips or band
of metal between which openings are left clear.
In a so-called combi-appliance is included an
insulated tank or reservoir of relatively small
dimensions from which hot tap water i5 immediately
available. A compact combi-appliance with a power of for
instance 22-24 kW has to be capable of providing 6 litres
of water per minute at 60~C from this insulated storage
tank. In the known combi-appliances however, it is found
in practice that, while water at 60~C is supplied for a
short time, the temperature of the tap water thereafter
decreases and a constant value above 60~C is reached only
after for instance one minute. This is particularly the
case if the heating appliance is not used or is used to a
lesser extent (as according to so-called modulating
operation) to heat fluid in pipes and radiators of the
heating system in the dwelling. Although a pre~erred
embodiment of the present invention is provided with such
a reservoir, another preferred embodiment is provided
with a heat exchanger which takes up little space.
The present invention further provides an apparatus
which is provided with a reservoir for temporarily
storing heated water, wherein the reservoir comprises a
second heat exchanger which is operationally coupled to
the first heat exchanger.
The first heat exchanger will preferably be provided
in the future with an inner pipe and an outer pipe,
whereby the tap water is further heated in the inner
pipe.
The apparatus according to the present invention is
preferably provided with a third heat exchanger which is
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3 ~ _
arranged in the discharge duct for the heated flue gases
and which serves to preheat the tap water.
The preferred embodiment with a reservoir is
preferably provided with pump means for pumping medium
round in the heating circuit provided with a rotation
speed regulation, or at least an ON/OFF control, wherein
the pump action is reduced or interrupted at the moment
wherein hot water is demanded from the hot water
reservoir by the user, or immediately thereafter,
whereby, in the case the apparatus is not used for
heating purposes, the relatively cold water from the
first heat exchanger is prevented from entering the
reservoir. If necessary, the burner is started and the
first heat exchanger heated, whereafter the pumping
action of the pump means is increased.
The flue gases are preferably urged closely along
the first heat exchanger for exchange of heat between the
flue gases and the heat exchanger with the greatest
possible efficiency, wherein for this purpose the side
walls of the annular space preferably have a contour at
least partially adapted to the outer contour of the heat
exchanger in order to further increase a laminated gas
~low along the heat exchanger.
As well as for room heating, thermal energy is also
required in a dwelling for a number of other purposes,
for instance for cleaning, such as hot air for a tumble
dryer or dish washer and the like, and also for cooking
and the heating of ventilation air for circulation in a
dwelling. This thermal energy is generated in most
dwellings using electricity, which is disadvantageous
from an energy efficiency viewpoint.
The present invention therefore further proposes to
provide the above stated apparatus with a heat exchanging
unit which is arranged in heat-conducting contact with
the top part of the apparatus and which is provided with
an inlet for infeed of medium for heating and an outlet
for heated medium.
~ =
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- Further advantages, features and details of the
present invention will be elucidated on the basis of the
following preferred embodiments thereof with reference to
the annexed drawings, in which:
figure 1 shows a partly cut-away view in perspective
of a preferred embodiment of an apparatus according to
the present invention;
figure 2 shows a graph illustrating the operation of
the preferred embodiment of figure 1;
figure 3 shows a partly broken-away view in
perspective of an alternative embodiment of the reservoir
shown in figure 1;
figure 4 is a partly sectional and partly
broken-away view in perspective of an alternative
embodiment of the burner and primary heat exchanger of
figure 1;
figure 5 is a partly broken-away side view of an
alternative embodiment of the primary heat exchanger of
figures 1 and 4;
figure 6 is a partly broken-away view in perspective
of the fixing to a wall of a preferred embodiment of the
apparatus according to the present invention;
figure 7 shows a diagram of a further preferred
embodiment for use of the apparatus according to the
present invention;
figure 8 shows a front view of a further preferred
embodiment of the present invention; and
figure 9 shows a view in perspective of a further
preferred embodiment of a reservoir for hot water for use
in an apparatus according to the present invention.
A heating apparatus 1 (figure 1) comprises a feed
line 2 for gas with a schematically designated gas
regulation 3 in addition to a schematically designated
fan 4 for feed of air to a burner 5 where the gas is
mixed with the air and combusted. The gas and the air are
mixed in a substantially hollow cylindrical inner sleeve
6 which may be provided with m; ~i ng means (not shown,~ and
which is provided with openings which debouch in a
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- combustion space around which a heat exchanger 8 is
disposed, which space is enclosed by a substantially
cylindrical outer sleeve 9 closed at the top. The gases
are deflected in downward direction and guided along heat
exchanger 8 between the outer wall of inner sleeve 6 and
the inner wall o~ outer sleeve 9. ~oth the inner wall of
outer sleeve g and the outer wall of inner sleeve 6 are
preferably adapted slightly in shape to the annular pipes
of heat exchanger 8 so that a good heat exchange takes
place between the hot gases and the content of the heat
exchanger.
The helical heat exchanger 8 preferably comprises an
inner pipe 10 and an outer pipe 11. Arranged on the inner
pipe for good heat transfer are star-shaped fin parts 12
which ma~e heat-conducting contact with outer pipe 11.
Flowing through inner pipe 10 is so-called tap water
which can be drawn off as hot water in a household using
a tap and which is supplied via a pipe 12. Tap water pipe
12 ends at connecting piece 13 onto which also connects a
supply line 14 which, via a three-way valve 16 and a pump
15, connects onto the circuit of a central heating system
via a feed line 17 and a discharge line 28.
In the present embodiment the tap water is further
supplied via a line 18 which, for preheating of the tap
water which has for instance a temperature of 5-15~C, is
arranged via a folded heat exchanger 19 in a discharge
part 20 for the flue gases. After flowing through the
inner pipe 10 of heat exchanger 8 the tap water is guided
via coupling piece 21 and line 22 to reservoir 23 for
- 30 temporary storage thereof, so that hot water is
immediately available to the user when a tap is opened.
Reservoir 23, which is well insulated in a manner not
shown, is provided with an inner sleeve 24 so that
incoming tap water is first of all driven in upward
direction as according to arrows C and subsequently ~lows
between outer wall 25 of the reservoir and inner sleeve
24 to drain stub 26 for drawing off the tap water (arrow
D).
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Arranged in the annular interspace of reservoir 23
is a second heat exchanger 27 through which flows the
fluid of the central heating installation supplied via
lines ~8, three-way valve 16 and line 29.
The apparatus according to the present invention is
pre~erably provided in a manner not shown with a control
unit which controls three-way valve 16, pump 15 and gas
regulation 3. Three-way valve 16 is controlled either to
heat the medium in an internal circuit or ~or use wherein
lQ heat must be supplied continuously to the central heating
circuit and the feed and discharge line of this central
heating circuit are in continuous connection thereto.
The curve in the graph of figure 2 shows tha~ when
tap water is drawn o~f in a dwelling with a pipe of
determined length between draw-off point and apparatus
according to the present invention, the temperature is at
a level of 60~C within + 15 seconds and also no longer
fa~ls below this level. During this measurement it has
been found that it is advantageous to slightly delay
starting of the pump for the primary heating fluid, for
instance for a duration of 5-15 seconds, or to set it at
a lower pumping level when the burner has to be set into
operation to supply the demanded amount of heat. Cold
water still present in the heat exchanger is thus
prevented from entering the reservoir before being
heated.
In a further preferred embodiment the apparatus
according to the present invention is provided with a
reservoir 50 (figure 3) for tap water which can be
manufactured more simply and at lower cost than the
reservoir 23 of figure 1. The tap water for heating is
guided via a ~eed line 51 on the underside of reservoir
50 into a groove between two successive windings 52 and
53 of a helical plate 55 arranged on an outer jacket 54,
so that the supplied tap water is preheated before
entering the interior of a heat exchanger 56 via an inlet
opening 57. An outlet line 58 on the underside of heat
-
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exchanger 56 is connected onto the interior thereof for
draining of the heated tap water.
In an alternative embodiment (not shown} the helical
plate 55 can be replaced by a plurality of concentric
discs arranged one above another and having openings for
passage of water.
Heat exchanger 56 comprises a large number of
substantially upright pipes which are connected via a
distributor (not shown) to a feed line 59 for hot central
heating water. At the top the upright pipes debouch into
a central return pipe 60 onto which connects a discharge
line 61 for the central heating water.
In an alternative embodiment of an apparatus
according to the present invention (figure 4) a helical
heat exchanger 68 is arranged in a space defined by an
outer sleeve 65, a cover 66 and an inner sleeve 67, which
heat exchanger comprises an outer pipe 69 and an inner
pipe 7~. In order to increase the combustion efficiency
the air supplied via a fan 71 is mixed with gas supplied
via a feed connection 72 by means of a plurality of
horizontally disposed plates 73, 74, 75, 76 respectively
which are provided in each case with passage openings
which are in shifted arrangement in successive plates in
order to obtain a well mixed, turbulent flow of the
mixture combusted in a burner 77. The gases leaving
burner 77 are guided along the pipes of heat exchanger 68
and discharged on the underside via an outlet 78 for the
flue gases. Due to the good mixing of air and gas a
complete combustion of the mixture is achieved whereby
the emission of C0 and NOX is avoided as far as possible.
In order to prevent excessive heating of the inner pipe a
closed baffle plate 80 is preferably arranged above the
plates 73-76 provided with openings.
Arranged in a further preferred embodiment between
an outer jacket 8~ (figure 5) and a helical pipe 88 is an
intermediate jacket 89 of substantially cylindrical form
in which openings 87 are arranged in accordance with the
pitch of the helical pipe of heat exchanger 88. In a
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manner not shown the pipe 88 can be provided with fins or
plate-like protrusions in order to increase heat
transfer. Due to the location o~ the openings 87 at the
position o~ the centre line of the helical pipe, the ~lue
gases are urged to flow as closely as possible along the
periphery o~ the helical pipe of the heat exchanger
be~ore arriving in an interspace 90, along which the flue
gases are discharged downward. In order to further
increase ef~iciency, partitions 91, 92 provided with
openings are further arranged along the lower helical
windings of heat exchanger 88, whereby the flue gases
flow further along the heat exchanger.
For installation and servicing operations it is
important that the apparatus according to the present
invention, which can be embodied very compactly, can be
mounted in simple manner on a wall, for instance in a
cupboard, while the accessibility to the interior of the
cupboard must be ensured. According to a preferred
embodiment of the present invention a cupboard 93 (figure
6), preferably consisting of a front part 94 which is
removable and a rear part 95, is fixed via this rear part
to a strip-like plate 96 which is mounted on a wall W
using screw bolts such as 97 and suspended therefrom. For
this purpose a plate 98 is fixed, preferably welded, to
the rear part 95, which plate engages behind a hooked end
99 in strip-like plate 96 and is hung thereon. In
addition, the underside of the rear part 95 is supported
on a profile 100 of substantially U-shaped cross-section
to which the feed and discharge lines for central heating
water and tap water can be fixed using clamping brackets
101, 102 etc. The diverse components, such as control
electronics 103 and other components (not shown) such as
the heat exchangers and the reservoir for the tap water,
are preferably arranged on the rear part 95 of cupboard
93 fixed firmly to wall W, for instance by means of
~rackets 104 placed therein. In another preferred
embodiment (not shown) the rear part 95 of the cupboard
can ~e provided on the underside with pins which engage
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- in recesses in bracket 100 whereby cup~oard 93 is also
prevented from being able to tilt forward because of its
weight.
In the embodiment of the present invention of figure
7, a further heat exchanger is arranged at the top of the
apparatus l according to the present invention, which
heat exchanger is placed in conducting contact with for
instance the discharge part 20 for the flue gases. At the
entrance to this further heat exchanger 40 relatively
cool air L is introduced, wherein the heated air is
carried via arrows M and N respectively into a dryer 41
for drying laundry in energetically responsible manner.
In the embodiment according to figure 8, in addition
to the burner construction 120 (such as that in figure 5)
with schematically designated mixing means 121, a heat
exchanger 122 is arranged instead of a reservoir for tap
water, whereby the invention can be embodied in even more
compact manner. At the top the apparatus 125 is provided
with preferably slidable connecting pieces 126 and 127
for easy connection of the air feed and the discharge of
the combustion gases. The diverse connections for central
heating water, gas and mains water are arranged at the
bottom. These connections are preferably clamped between
a formed piece on the cupboard and a counter-piece
fixedly screwable thereon so that the diverse components
can be assembled in a cupboard in lyin~ position,
whereafter the counter-piece is screwed fittingly into
place over the connections. This facilitates assembly and
installation operations.
Most probably because of the good thermal balance,
whereby large thermal differences do not occur in the
compact design of the apparatus according to the present
invention, it has been found that the emission of N0x and
CO in this appliance according to the present invention
have extremely low values. Measurements have shown that
the efficiency of the apparatus according to the present
invention amounts to theoretically 100~, in any case
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- considerably more than 95%, while the emission o~ Co and
NOX is very low (maximum ca. 9S ppm (at 32 kW)
respectively ca. 13 ppm (at 32 kW)~.
A further preferred embodiment for a so-called
draw-off pot for hot water (figure 9) is constructed from
a substantially cylindrical vessel 130 which can be of
metal but which is preferably assembled from two plastic
shells respectively 131, 132 which can be fixed
releasably to each other with connecting means ~not
shown) such as bands or screw bolts in order to open and
clean the reservoir in the case of lime scale. Arranged
in vessel 130 is a helical metal tube 133, preferab~y of
metal, around which is arranged a pipe or hose 134 of for
instance thin plastic (wall thic~ness of for instance
less than 1 mm~. Via connecting stub 135 hot water is
carried out of the heating system into the helical inner
pipe 13-3, while the water is returned to this system at
the top via connecting stub 136. The tap water for
heating is carried via connecting stub 137 into vessel
130, while that water in the interspace between the
plastic hose 134 and the helical inner pipe 133 is guided
downward via the top part into connecting stub 138 to
which a hot water line is connected. Spacers are arranged
in a manner not shown at determined locations between
inner pipe 133 and plastic hose 134 in order to prevent
the passage for the water to be heated from being
~locked. A temperature sensor is likewise arranged in the
vessel in a manner not shown close to connecting stub
137, which sensor senses whether the temperature of the
water in the vessel falls below for instance ~0~C,
wherea~ter hot central heating water must be supplied.
The water for heating is first preheated during the
upward movement thereof, while it is heated very strongly
dur~ng the downward movement between helical pipe 133 and
plastic hose 134. Because use is made of a plastic hose
arranged round the helical inner pipe 133, a heat
exchanger is obtained which is extremely favourable in
terms of cost, while for the inner pipe use can be made
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11 ' -
of standard, commercially available elements. The
structure is so compact that it can be incorporated in
the compact heating appliances described in the
foregoing.
The present invention is not limited to the above
described preferred embodiments thereof. Many
modifications can be envisaged within the scope of the
present invention, which is defined by the following
claims. An example of such a non-limiting modification is
the placing of a second tap water reservoir in the
appliance according to the present invention, since space
is still available in the inner space thereof and the
stable high temperature of the tap water can thereby be
ensured even more precisely.
