U.S. patent application number 14/402549 was filed with the patent office on 2015-05-21 for heating arrangement for heating a fluid utilizing a solar panel.
This patent application is currently assigned to SoleAer AB. The applicant listed for this patent is SoletAer AB. Invention is credited to Adam Fjaestad.
Application Number | 20150136116 14/402549 |
Document ID | / |
Family ID | 49624169 |
Filed Date | 2015-05-21 |
United States Patent
Application |
20150136116 |
Kind Code |
A1 |
Fjaestad; Adam |
May 21, 2015 |
HEATING ARRANGEMENT FOR HEATING A FLUID UTILIZING A SOLAR PANEL
Abstract
The present invention relates to a heating arrangement for
heating a fluid, comprising a first heat exchanger loop (5),
arranged to act on a fluid to be heated, and a second heat
exchanger loop (8), arranged to also act on said fluid to be
heated, wherein said second heat exchanger loop (8) is connected to
a panel (4) that serves as a solar collector and that is arranged
to heat at least a part of said second heat exchanger loop (8).
Inventors: |
Fjaestad; Adam; (Arvika,
SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SoletAer AB |
ARVIKA |
|
SE |
|
|
Assignee: |
SoleAer AB
Arvika
SE
|
Family ID: |
49624169 |
Appl. No.: |
14/402549 |
Filed: |
May 21, 2013 |
PCT Filed: |
May 21, 2013 |
PCT NO: |
PCT/SE2013/050578 |
371 Date: |
November 20, 2014 |
Current U.S.
Class: |
126/640 ;
126/643 |
Current CPC
Class: |
F24D 11/0221 20130101;
Y02B 10/20 20130101; F24D 2200/14 20130101; Y02A 30/272 20180101;
Y02B 10/24 20130101; F25B 27/005 20130101; F24H 4/04 20130101; F24D
17/02 20130101; F24S 10/00 20180501; F24D 2200/12 20130101; Y02B
10/70 20130101; Y02E 10/44 20130101 |
Class at
Publication: |
126/640 ;
126/643 |
International
Class: |
F24J 2/04 20060101
F24J002/04 |
Foreign Application Data
Date |
Code |
Application Number |
May 21, 2012 |
SE |
1250511-1 |
Claims
1-12. (canceled)
13. A heating arrangement for heating a fluid, comprising a first
heat exchanger loop for receiving heat from ambient air, said first
heat exchanger loop being arranged to act on a fluid to be heated,
and a second heat exchanger loop, arranged to also act on said
fluid to be heated, said second heat exchanger loop including
tubing having a heat absorbing portion and a heat supplying portion
being connected to a panel that serves as a solar collector and
arranged to heat said heat absorbing portion, wherein said panel is
arranged to drive said second heat exchanger loop by heating and
evaporating a refrigerant inside of said heat absorbing
portion.
14. The heating arrangement according to claim 13, wherein said
panel is arranged near an air inlet to serve as a moisture trap for
air humidity.
15. The heating arrangement according to claim 13, wherein said
panel is also connected to said first heat exchanger loop and
arranged to heat said first heat exchanger loop.
16. The heating arrangement according to claim 14, further
comprising an evaporator connected to said first heat exchanger
loop, said evaporator being arranged so that at least a part of
said panel is placed between said evaporator and said air
inlet.
17. The heating arrangement according to claim 13, further
comprising a heat exchanger tubing arranged so that said fluid to
be heated can flow through said tubing, wherein said heat exchanger
tubing further houses at least a part of said first heat exchanger
loop and said second heat exchanger loop.
18. The heating arrangement according to claim 13, further
comprising a transparent outer wall arranged so that an air inlet
flow gap is formed between said transparent outer wall and said
panel.
19. The heating arrangement according to claim 18, wherein said air
inlet is located at a lower end of said air inlet flow gap.
20. The heating arrangement according to claim 19, wherein said air
inlet flow gap is further arranged to act as a defroster by holding
a quantity of air to be heated by sunlight against said panel.
21. The heating arrangement according to claim 13, wherein said
panel is further arranged to act as a defroster by receiving
sunlight to melt any ice formed on a surface of said panel.
22. The heating arrangement according to claim 13, further
comprising a fan for circulating air in said heating
arrangement.
23. The heating arrangement according to claim 13, further
comprising a control unit.
24. A heating system comprising a tank for a fluid to be heated and
a control unit for controlling a heating operation of said fluid,
wherein said heating system further comprises a heating arrangement
according to claim 13, said heating arrangement being arranged to
be controlled by said control unit for heating said fluid.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heating arrangement for
heating a fluid, comprising a first heat exchanger loop, arranged
to act on a fluid to be heated, and a second heat exchanger loop,
arranged to also act on said fluid to be heated.
BACKGROUND ART
[0002] Many kinds of heating arrangements are known within the area
of heating a fluid such as water for a building. In a house, the
water used as tap water needs to be heated to a suitable
temperature and maintained in a tank for use when desired, and to
provide such heated water by conventional methods is generally
costly.
[0003] To reduce costs, renewable energy sources such as solar
panels can be used, but in colder climates it is generally
difficult to achieve the power needed to heat tap water all year
round, due to the size of solar panels required and the costs
associated therewith. During bright summer months, however, the
solar panels necessary in winter would not be needed, giving
redundancies in the heating system and excessive energy for heating
the water. As a consequence, fluids in the solar panels can be
brought to boil, causing damages and creating the risk for freezing
damages in winter.
[0004] Some systems to address these problems are known, but are
mostly too expensive and bulky to be used by consumers living in
smaller houses. In many houses, an air to air heat pump is mounted
to heat indoor air, but installing an air to water heat pump to
also heat the tap water and/or water for radiators and the like is
more costly and therefore avoided. Also, for houses with heating
systems already in place, the remodelling of the heating systems to
more efficient systems is in itself costly and therefore not
beneficial for consumers in general.
[0005] Another problem facing users of such heating arrangements is
the need for defrosting in colder climates, to avoid an
unacceptable loss of efficiency due to the formation of an ice
coating on parts of the arrangement. Defrosting generally requires
a lot of energy and also prevents the arrangement from being used
for heating water during defrosting operation, resulting in further
losses.
[0006] There is therefore a need for a convenient and cost
efficient heating arrangement suitable for heating tap water in
houses that combine the advantages of renewable energy sources and
the reliability of more conventional energy sources, without adding
unduly to the cost of installing and maintaining such an
arrangement.
DISCLOSURE OF THE INVENTION
[0007] The object of the present invention is to eliminate or at
least to minimize the problems described above. This is achieved by
a heating arrangement according to the appended claim 1 with a
panel serving as a solar collector for said second heat exchanger
loop. Thereby, the fluid to be heated, preferably tap water, can be
heated continuously when the sun is shining against the panel and
the first heat exchanger loop is arranged to contribute to the
heating of said fluid at times when the sunlight is insufficient to
heat the fluid to the desired temperature.
[0008] In a preferred embodiment of the invention, said panel is
arranged to drive the second heat exchanger loop. Thereby, the
second heat exchanger loop can operate continuously when the sun is
shining, without requiring control by a controlling unit or the
like, and only the first heat exchanger loop needs to be controlled
to contribute to the heating of the fluid when needed.
[0009] It is beneficial to mount said panel on the heating
arrangement near an air inlet so that it can serve as a moisture
trap for air humidity. Thereby, the double advantage of preventing
condensation on components in the heating arrangement at a further
distance from the air inlet, and of having the panel receive the
energy released during condensation can be achieved.
[0010] Preferably, the heating arrangement further comprises an
evaporator connected to the first heat exchanger loop that is
arranged so that at least a part of said panel is placed between
the evaporator and the air inlet. Thereby, a condensation on the
evaporation can largely be prevented, as mentioned above, and the
benefits of having air from the air inlet flowing through the
evaporator can still be achieved. Thus, the evaporator serves to
heat a refrigerant inside the first heat exchanger loop.
[0011] It is advantageous for the heating arrangement to comprise a
heat exchanger tubing arranged to that said fluid to be heated,
i.e. a tap water, can flow through said tubing while the tubing at
the same time houses at least a part of both said first heat
exchanger loop and said second heat exchanger loop. Thereby, both
heat exchanger loops can act on the fluid to be heated and the heat
transfer between each of the heat exchanger loops and the fluid to
be heated can be facilitated.
[0012] Preferably, a transparent outer wall is mounted on the
heating arrangement in such a way that an air inlet flow gap is
created between said transparent outer wall and the panel. Thereby,
a quantity of air is constantly present between the wall and the
panel and can be heated by sunlight falling through the transparent
outer wall and onto the panel. Through this warming of the air, a
defrosting operation of the panel and the evaporator can be
achieved, making any ice formed melt and slide from the panel and
evaporator. Preferably, the air inlet is at a lower end of said air
inlet flow gap, giving the added advantages that the heated air
remains in the air inlet flow gap, being prevented from escape by
the fact that colder air outside the heating arrangement is present
at the air inlet and that the ice being melted can slide downwards,
out of the heating arrangement, without requiring specific
removal.
[0013] It is advantageous for the heating arrangement to comprise a
fan for circulating air in said heating arrangement. Thereby, a
constant flow of air through the evaporator can be created, acting
to heat a refrigerant in said first heat exchanger loop and to
circulate air for faster defrosting, in the case of the air around
the heating arrangement being at a temperature above zero degrees
Celsius.
[0014] Preferably, the heating arrangement also comprises a control
unit for controlling the various aspects of the arrangement, in
particular the operation of the first heat exchanger loop.
[0015] More advantages of the invention will be readily understood
by the person skilled in the art in view of the detailed
description below.
BRIEF DESCRIPTION OF THE FIGURES
[0016] In the following the invention will be described more in
detail with reference to the enclosed figures where;
[0017] FIG. 1 shows a schematic front view of an arrangement
according to the invention,
[0018] FIG. 2 shows a cross-sectional view along line B-B in FIG.
1,
[0019] FIG. 3 shows a cross-sectional view along line A-A in FIG.
1,
[0020] FIG. 4 shows a view from above of an arrangement according
to the invention being attached to the wall of a house,
[0021] FIG. 5 shows a vertical cross-section along line C-C in FIG.
4,
[0022] FIG. 6 shows a schematic view of a part of a building having
an arrangement according to the invention attached thereto, and
[0023] FIG. 7 shows a schematic side view of the first and second
heat exchange loops in a cross-sectional side view of the heating
arrangement, together with the fluid to be heated.
DETAILED DESCRIPTION
[0024] In FIGS. 1, 2 and 3 there is schematically presented an
arrangement 100 in accordance with the preferred embodiment
according to the invention. At a front side of the arrangement 100
is a transparent outer wall 2 and at a distance t.sub.1 inside of
the transparent outer wall 2 there is positioned a panel 4,
preferably in the form of a metal wall 4. Between the wall 2 and
panel 4 there is formed an inlet airflow gap 7 for a flow of air F.
The transparent outer wall 2 is at its top connected to an outer
casing 13, having a top wall 13A, a back wall 13B, sidewalls 13C
and a bottom 13D. The back wall 13B is arranged at a distance
t.sub.2 (that is larger than t.sub.1) away from panel 4, forming a
down flow compartment 7D and larger space than the inlet airflow
gap 7. The bottom 13D extends horizontally between the back wall
13B and the panel 4 but not between the panel 4 and transparent
outer wall 2, thereby creating a downwards facing open gap 7A
between said transparent outer wall 2 and the panel 4. The panel 4
extends upwards from the bottom 13D but does not reach the top wall
13A, thereby forming an open gap 7B between an upper edge of the
panel 4 and the top wall 13A of the outer casing 13.
[0025] Further, as shown in FIG. 5, there are arranged outlet holes
7C at corner sections in a lowermost portion of the outer casing
13, allowing air F to pass above the edge of the panel 4 and
thereafter downwards between the panel 4 and the back wall 13B of
the outer casing 13 and finally out through the openings 7C in the
corner areas between the side walls 13C and the bottom 13D. A fan
10 is positioned in the space between the rear wall 13B and the
panel 4.
[0026] The arrangement includes a first heat exchange loop 5 and a
second heat exchanger loop 8 that are arranged to heat a fluid such
as tap water. The first heat exchanger loop 5 is of a conventional
kind with a tubing containing a refrigerant such as R134a
(tetrafluorethane, CH.sub.2FCF.sub.3) or R744 (carbon dioxide,
CO.sub.2), said tubing forming a closed loop inside the heating
arrangement 100. It is especially advantageous to use CO.sub.2 as
the refrigerant, thanks to its suitable thermodynamic properties.
Other suitable refrigerants are R-600a (isobutane, C.sub.4H.sub.10)
and propane (C.sub.3H.sub.8). Thanks to the placement of the
heating arrangement outside a building, the risk for an explosion
or fire in the case of leakage of a refrigerant from the heating
arrangement can be largely eliminated.
[0027] In the downflow compartment 7D, a low pressure part 5B of
the first heat exchanger loop leads from an expansion valve 9 to a
heat absorbing part 5C of the tubing that is mounted in a zig-zag
shape on the panel 4 in such a way that the refrigerant inside the
tubing can be heated by the panel 4 if the panel 4 has a higher
temperature than said refrigerant. Preferably, the boiling point of
the refrigerant used is low enough to be heated when in contact
with the panel 4 even during cold winter days, so that a heating
will take place even if the temperature is around -15 to
-20.degree. C. Thus, said panel 4 is arranged to drive said second
heat exchanger loop 8 by receiving sunlight and heating at least a
part of said second heat exchanger loop 8.
[0028] From the heat absorbing part 5C of the first heat exchanger
loop 5, the tubing leads to an evaporation part 5D in an evaporator
3 that is mounted at an upper end of the air inlet flow gap 7
between the panel 4 and the outer wall 2.
[0029] The evaporator 3 has a length extension that substantially
exceeds the width t.sub.1 in the air inlet flow gap 7 and is
preferably fitted within the gap 7 at a sharp angle a in relation
to the transparent wall 2 and the panel 4. Further, the evaporator
3 is of a rectangular shape with corners that are beveled to create
a larger area of contact between the evaporator 3 and the
transparent wall 2 and panel 4, respectively. The evaporator is of
a flange type, having through channels that are perpendicularly
directed in relation to the vertical extension of the evaporator 3.
Thanks to this positioning, the risk for clogging of airways of the
evaporator due to frost is minimized and the distribution of the
air flowing through the evaporator 3 is optimized. Also, the open
gap 7B is provided with two openings in the form of through holes
7F that further serve to distribute the air flowing in the gap 7B
so that an even distribution in the evaporator 3 is achieved. In
the low pressure part 5B, the refrigerant is in the form of a
fluid, but starts to be heated and to boil in the heat absorbing
part 5C.
[0030] Thus, the evaporator serves to further heat the refrigerant
inside the evaporation part 5D. At this stage, the refrigerant has
been completely transformed from a fluid to a gas. From the
evaporator 3, the first heat exchanging loop 5 leads to a
compressor 6, where the gas of the refrigerant is pressurized to
further increase its temperature, forming a pressurized part 5A.
The pressurized part 5A is now lead into a spirally arranged heat
exchange tubing 12, where the fluid to be heated is allowed to flow
in the tubing 12 around said pressurized part 5A to form a
counter-flow heat exchanger. After passing through the tubing 12,
the pressurized part 5A is lead to the expansion valve 9 that
serves to lower the pressure and allow the refrigerant to condense
and pass into the low pressure part 5B and continue the loop as
described above. It is advantageous for the tubing 12 to be a PEX
tubing (made from cross-linked polyethylene) that can sustain a
high pressure and be elastically deformed if the fluid to be heated
should freeze inside the heating arrangement. The tubing 12 can
expand to accommodate a larger volume of ice and shrink to its
regular size upon melting, without causing damages to the heating
arrangement. Other materials with these properties are also
suitable for use in the tubing 12.
[0031] The compressor preferably has a relatively small capacity,
i.e. in the range of 500-800 W. Thanks to this arrangement, extra
environmental advantages such as less material consumption upon
manufacture and smaller energy requirements during operation, among
others, may be gained and also advantages from a cost perspective
may be gained due to the fact that compressors in this size are
produced in large series, e.g. to be used in refrigerators.
[0032] The second heat exchanger loop 8 is preferably a solar
collector loop using the panel 4 as a solar panel to heat a
refrigerant. In some embodiments, it is suitable to use the same
refrigerant in the second heat exchanger loop 8 as in the first
heat exchanger loop 5, but different refrigerants can also be
used.
[0033] The second heat exchanger loop 8 is preferably a
thermosiphon using the panel 4 as a driver and having a heat
absorbing portion 8A mounted on the panel 4, preferably on a rear
side of said panel 4 facing away from the gap 7. The refrigerant
inside the tubing of the second heat exchanging loop 8 is thus
heated and brought to boil and transition to a gas phase if the
panel 4 is of a temperature higher than the boiling point of the
refrigerant. The gas is transported to a heat supplying part 8B in
the form of a spiral within the heat exchanging tubing 12, mounted
adjacent to the pressurized part 5A of the first heat exchanger
loop 5 so that the fluid to be heated can flow around the heat
supplying part and a counter-flow heat exchanger is thus
created.
[0034] The heat exchanging tubing 12 is enclosed within an
isolating enclosure 11, 16. The tubing 12 has a relatively large
diameter, e.g. in the range of 20-50 mm, enabling the heat
supplying portion 8B and pressurized part 5A of the loops 5, 8 to
be housed therein without occupying a major space, i.e. also
providing a surrounding space. The surrounding space within the
heat exchange tubing 12 is intended for heating of tap water used
in the house, e.g. in a heat water tank 15 (as will be explained
more in detail in relation to FIG. 6).
[0035] FIG. 4 shows how the arrangement 100 preferably is designed.
Accordingly, the transparent outer wall 2 and also the panel 4 are
curved, preferably to have a common center of their radius, whereby
the gap 7 formed between them will be the same in any vertical
cross section going through the center line. Further it is shown
that the side walls 13C of the outer casing are angled to converge
in a direction towards the back wall 13B. Moreover, insulation 16
is applied at different parts within the arrangement 100. As
already mentioned, the casing 11 has a layer of insulation 16 Also,
the back wall 13B has a layer of insulation applied thereto to
cover said back wall 13B. Further, the inner side of the top wall
13A has insulation 16 as well as the upper inner sides of the side
walls 13C. Finally there is an isolating partitioning 16A that at
its center has a through passage 18 for the fan 10.
[0036] FIG. 7 discloses schematically the flow of the first and
second heat exchanger loops 5, 8, showing the tubing 12 containing
the fluid to be heated that is transported through a wall 30 of the
building to reach the heating arrangement 100 and return into the
building after heating. The first heat exchanger loop comprises the
expansion valve 9, the zig-zag formation mounted on the panel, the
segment 5C mounted on the evaporator 3 and the compressor 6; and
the second heat exchanger loop 8 comprises a thermosiphon 8 with a
segment mounted on the panel 4 and continuing towards the tubing 12
where the fluid is heated, as is also described in more detail
above.
[0037] The arrangement according to the invention provides a novel
concept where the advantages of a solar collector are combined with
the advantages of an air heat pump, in a very efficient manner,
wherein the solar collector is the driver of the second heat
exchanger loop 8 (thermosiphon loop) and the air heat pump is the
driver of the first heat exchanger loop 5 (conventional heat
exchanger loop). A major advantage of the arrangement according to
the invention is the use of a relatively cheap heat absorbing unit,
i.e. panel 4, to be used for heat collection for both of the loops
5, 8. Preferably, the panel 4 is made from a metallic material such
as aluminium or copper or a combination thereof, but any material
that can absorb heat and transfer it to the heat exchanger loops 5,
8 is suitable for use with the invention.
[0038] An exemplary embodiment, wherein the arrangement according
to the invention is used to heat tap water, in a house, could be
arranged as follows: A hot water tank 15 is assumed to be set for a
max temperature of 60.degree. and the fresh water supplied to the
house may be assumed to have a temperature of 10.degree. C. A minor
loop of fresh cold water of 10.degree. C. is diverted from the
supply pipe 20 (to the heat water tank 15), by means of a
T-coupling enabling a substantially smaller flow of water in a
supply line 21 to the heat tubing 12 for tap water. The cold water
supplied to the heat tubing 12 will flow in a counter flow in
relation to the two loops 5A, 8B and absorb heat from these loops,
wherein the flow is controlled to provide for a temperature of
60.degree. C. when the heated water exits the heat tubing 12, into
a return line 22. Thanks to the sporadic use of heated water in a
normal house, a relatively low flow of heated water may be
sufficient to keep a desired temperature within the heat water tank
15. On the other hand, the existing heating system for the heat
water tank may of course be used in combination with the invention,
if temporarily extra high use of heated water is desired.
[0039] During a hot summer day, the second heat exchanger loop 8
can be sufficient to heat the water of the tank 15 to a suitable
temperature for use within a building, but in most cases the first
heat exchanger loop 5 is also required to achieve the desired
temperatures. The heating arrangement is preferably part of a
heating system and operated by a control unit, using at least one
sensor to collect data regarding the temperature at predetermined
levels in the water tank 15, the air temperature near the heating
arrangement, and other relevant data for the operation of the
heating arrangement. By monitoring the temperature in the water
tank 15, it can be determined when the first heat exchanger loop 5
needs to be operated, and a user of the system can decide what
temperature is suitable for the water in the water tank 15. It is
advantageous to keep the flow of fluid to be heated low, for
instance at 7-10 litres per hour, to allow for sufficient heating
by the first and second heat exchanger loops 5, 8 and to create a
gradient inside the tank 15.
[0040] It is advantageous to allow a user of the heat arrangement
100 and water tank 15, i.e an inhabitant of the building, to select
the desired temperature in the tank 15.
[0041] Three different operation modes will now be described, to
further exemplify the operation of the heating arrangement
according to the invention.
[0042] In a first operating mode, it is assumed that the outdoor
temperature is at -10.degree. C. This will also be the temperature
of the air flowing into the air inlet 7E and upwards through the
air inlet flow gap 7. In the evaporator 3, the air will pass
through in cross flow manner in relation to the refrigerant in the
loop 5. Thereby, the refrigerant will have its temperature
increased from about -20.degree. C. to approximately -15.degree. C.
The refrigerant will then be compressed by the compressor 6
implying a temperature increase to about 70.degree. C. In the heat
tubing 12, the compressed refrigerant will have its temperature
lowered to about 30.degree. C. after acting to warm the fluid
inside the tubing 12, and afterwards reaches the expansion valve 9,
whereby the temperature will drop to about -20.degree. C.
Thereafter, it will absorb some heat from the panel 4 prior to
again entering into the evaporator 3. The air leaving the heat
arrangement through the outlet holes 7C has a temperature of about
-12.degree. C.
[0043] The termosiphon 8 will supply heat to the heat tubing 12 by
absorbing solar energy from the panel 4 and deliver it at a
temperature of about 70.degree. in its tubing running in parallel
with the other loop 5B within the heat tubing 12. It is to be noted
that when the sun is shining there may not be any need to run the
air heat pump, i.e. the compressor 6 may be inactive. Likewise it
is possible to increase the heat energy taken from the air heat
pump (e.g. when there is no sunshine) by means of increasing the
air flow by activation of the fan 10. In a preferred embodiment,
the fan 10 is variably driven allowing for stepless control of the
air flow.
[0044] It is advantageous that the rotational speed of the fan 10
can be varied, depending on how loud noises from the fan 10 are
allowable at a given time. When the air surrounding the heating
arrangement 100 is warmer than 10.degree. C., for instance, it may
be more likely that persons are present in a vicinity of the
heating arrangement 100 to enjoy nice weather. At such times, the
fan 10 can be driven at a lower rotational speed so that a lower
noise is produced. Conversely, when the air is cold, the fan can be
used at a higher rotational speed that gives a higher level of
noise. The placement of the fan 10 inside the heating arrangement
10 near insulation also allows for a damping of the noise by
allowing the insulation to absorb the noise.
[0045] The positioning of the compressor 6 at the top of the
housing 2, 13 provides the advantage that it will be located in the
hottest part of the arrangement, bringing about advantages related
to the runability and reliability of the compressor 6. Thanks to
the placement of the compressor 6, no additional heating to prevent
the compressor 6 from getting colder than other components is
required. If the temperature gets lower than other components, the
risk would arise that refrigerant would condense inside the
compressor, causing said refrigerant to be mixed with oil from the
compressor 6 during use and allowing said oil to spread through the
first heat exchanger loop 5. But thanks to the advantageous
placement of the compressor 6, this scenario can be avoided without
the use of any additional components.
[0046] In order to optimize the flow through the evaporator 3, the
insulation casing 11 should preferably be positioning at the
center, high up, in the downflow channel 7D of the arrangement 100,
since such a positioning will promote a higher flow in the inlet
channel 7 near the edges, thereby providing a ultimate distribution
of the flow through the evaporator 3, since normally a much higher
through flow is obtained in the center to area through an air heat
exchanger 3. A further advantage according to the concept, related
to the air flow, is that fan 10 is positioned downstream of the
evaporator 3, since a sucking fan provides a more even through flow
than a pushing fan.
[0047] In a second operation mode, the outdoor temperature is at
+0.degree. C. The refrigerant in the first heat exchanger loop is
at a temperature of about -10.degree. C. before entering the
evaporator 3 and about -5.degree. before compression. The air
leaving the heating arrangement 100 through the outlet holes 7C is
at a temperature of about -2.degree. C.
[0048] In a third operation mode, the outdoor temperature is at
20.degree. C. The refrigerant in the first heat exchanger loop is
at a temperature of about +10.degree. C. before entering the
evaporator 3 and about +15.degree. before compression. The air
leaving the heating arrangement 100 through the outlet holes 7C is
at a temperature of about 18.degree. C.
[0049] The moisture content in the air flowing into the air inlet
7E varies with the temperature. Inside the air inlet flow gap 7, a
condensation may occur, giving a coat of moisture to any surfaces
adjacent to the air flow. In some cases, the moisture may freeze to
form a coat of ice. This will occur in the first operation mode and
in the second operation mode described above. The presence of an
ice coating will in most cases severely lower the performance of
the heating arrangement 100, giving rise to the need for defrosting
at regular intervals. In conventional heating arrangements, it is
common practice to schedule a defrosting operation at given
intervals, but this is, as has also been mentioned above, energy
consuming.
[0050] Thanks to the arrangement according to the invention,
defrosting has been significantly simplified and can be performed
at a fraction of the cost in a regular heating arrangement.
Firstly, thanks to the operation of the second heat exchanger loop
8, the need for air circulation in the heating arrangement 100 is
lowered at times when the sun is shining since this second loop 8
does not require air circulation to function. Secondly, thanks to
the placing of the panel 4, most of the moisture entering the air
inlet 7E will become attached to the panel 4, being the first
surface encountered by the air that is colder than the air itself.
Thus, ice formation on the evaporator 3 can largely be prevented.
Thirdly, thanks to the width t.sub.1 of the gap between the wall 2
and the panel 4, the ice layer forming on the panel 4 can be
relatively thick without disturbing the flow of air through the air
inlet flow gap 7, thus also lowering the frequency of defrosting
required. Thanks to these advantages of the invention, the need for
defrosting can be lowered from about once per hour (as required by
some conventional heating arrangements) to once every few days.
[0051] When an ice layer has formed on the panel 4 and the
evaporator 3, a number of efficient ways are presented, thanks to
the invention, for removing said ice. Firstly, when the sun is
shining, the air trapped between the transparent wall 2 and the
panel 4 is heated, increasing the temperature in the air inlet flow
gap 7. This is in many cases sufficient to start a thawing at the
evaporator 3 and the panel 4, melting the ice and allowing it to
fall off or drip down through the air inlet 7E. When the sunshine
heats the panel 4, the layer closest to said panel 4 will be
melted, resulting in the entire ice coating falling off.
[0052] Secondly, if the temperature of the surrounding air is above
zero, simply starting the fan 10 and allowing air to circulate
through the heating arrangement will result in a melting of the ice
regardless of whether the sun shines.
[0053] Thirdly, the first heat exchanger loop 5 can be used in a
thawing operation by opening a second valve 9A, placed in parallel
to the expansion valve 9, that allows the refrigerant in the first
heat exchanger loop 5 to circulate without being expanded to a
lower pressure. Thereby, the temperature of the refrigerant will be
at about 30.degree. C. as described above in relation to the first
operation mode, and this in itself will be enough to heat the panel
4 and the evaporator 3 and allow the ice to melt and fall off.
[0054] Thus, ice removal can be performed in a simple and
convenient manner, and need not be performed nearly as often as in
conventional heating arrangements of this type. This is a
significant advantage of the present invention.
[0055] In an alternative embodiment of the invention, it is
possible to mount a plurality of panels 4 and transparent walls 2
to form a semicircle on a wall of a house, making it possible to
catch sunlight from more angles and giving a more efficient warming
of the panels 4. In some embodiments, it may be advantageous to use
a plurality of second heat exchanger loops 8 for this purpose.
[0056] It is also possible to create a separate unit of the heating
arrangements to be mounted at a distance from a wall of a building,
for instance in a garden near a building. The water tank 15 could
in this embodiment be connected through pipes in the ground or be
placed inside the separate unit described above. In this case, the
tap water is transported to the building.
[0057] Thanks to the invention, the heating of the fluid from the
tank 15 can continue even if a freezing of one of the first and
second heat exchanger loops 5, 8 should occur, simply by running
the other of said loops 5, 8 alone. Even if both loops 5, 8 were to
freeze, the heating of the fluid could continue at the water tank
by using a standard heating device.
[0058] The invention is not to be seen as limited by the preferred
embodiment described above, but can be varied within the scope of
the claims, as will be readily apparent to the person skilled in
the art. For instance, the heating portions of the loops can be
separated to act on the fluid to be heated at separate locations
within the heating arrangement, rather than at the same time inside
the tubing. Also, another heat exchanger can be used instead of the
PEX tubing, such as a tank, for instance, to allow the first and
second heat exchanger loops to act on the fluid to be heated. The
configuration of the tank 15 can also be varied and it could
alternatively be integrated into the heating arrangement outside
the building. The evaporator can also be of a different type than
the flange type described above.
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