EP2012071A2 - Heat exchanger for a boiler and gas boiler, in particular a condensation boiler, provided with said heat exchanger - Google Patents

Heat exchanger for a boiler and gas boiler, in particular a condensation boiler, provided with said heat exchanger Download PDF

Info

Publication number
EP2012071A2
EP2012071A2 EP20080159622 EP08159622A EP2012071A2 EP 2012071 A2 EP2012071 A2 EP 2012071A2 EP 20080159622 EP20080159622 EP 20080159622 EP 08159622 A EP08159622 A EP 08159622A EP 2012071 A2 EP2012071 A2 EP 2012071A2
Authority
EP
European Patent Office
Prior art keywords
heat exchanger
pipe
exchanger according
axis
essentially
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP20080159622
Other languages
German (de)
English (en)
French (fr)
Inventor
Roberto Cavallini
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fondital SpA
Original Assignee
Fondital SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fondital SpA filed Critical Fondital SpA
Publication of EP2012071A2 publication Critical patent/EP2012071A2/en
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
    • F24H1/22—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating
    • F24H1/40—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water tube or tubes
    • F24H1/43—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water tube or tubes helically or spirally coiled

Definitions

  • the present invention relates to a heat exchanger, in particular for a gas boiler used to produce hot water, and to a gas boiler for producing hot water provided with said heat exchanger.
  • the invention is particularly suitable for use in condensation boilers, to which reference is made in the following description purely by way of example.
  • a gas boiler for producing hot water normally comprises a gas burner and at least one heat exchanger in which the combustion fumes produced by the burner transfer heat to circulating water.
  • Condensation boilers condense the steam in the combustion fumes and also transfer the latent heat in the fumes to the water.
  • the exchange of heat between the fumes and the water and the condensation of the fumes can be performed in separate heat exchangers or in a single heat exchanger which provides solely for heat exchange in a first portion and for both heat exchange and fume condensation in a second portion.
  • the condensation boilers of the known type are provided with heat exchangers comprising a casing through which the fumes flow and housing a coiled pipe through which the water flows; the fumes flow between the turns of the pipe, over the outer surface of the pipe and transfer heat to the water flowing along the pipe.
  • a known method for improving heat exchange efficiency consists of providing the outer surface of the coiled pipe with various types of fins.
  • finned pipes are relatively complex and expensive to produce, and are not entirely satisfactory in terms of heat exchange efficiency.
  • the coiled pipe has a cross-section (flow cross-section) that is essentially round or rectangular or, in some cases, a flattened oval or ellipse shape.
  • the outer surface of the pipe is essentially convex or flat in each point of the pipe.
  • the gap between two successive turns of the pipe, through which the fumes flow, is thus delimited by opposing convex surfaces or essentially parallel flat surfaces. These surfaces essentially delimit a channel through which the fumes flow which extends along an essentially rectilinear axis and may have a centrally throttled cross-section; this geometry causes flows with reduced heat exchange efficiency.
  • this geometry allows the flame of the burner to directly irradiate the wall of the casing, which is not shielded in a radial direction, further reducing the overall efficiency of heat exchange.
  • the purpose of the present invention is to provide a heat exchanger for a gas boiler for producing hot water that overcomes the drawbacks described above in a simple and inexpensive manner, both in terms of functionality and construction.
  • one purpose of the invention is to provide a heat exchanger that is extremely efficient in terms of heat exchange and that is also simple and inexpensive to produce.
  • a heat exchanger is produced as set forth in claim 1.
  • reference number 1 indicates, as a whole, a gas boiler for producing hot water, in particular a condensation boiler; it is, however, understood that the invention may be applied to other kinds of boilers; the boiler 1 may be used to produce hot water for a sanitary water system and/or to supply a heating system.
  • the general structure of the boiler 1 is essentially known and only the essential components thereof are described below; the boiler 1 comprises an outer structure 2, which is of a known type and only schematically illustrated in figure 1 , in which are housed a gas burner 3, a heat exchanger 4, a conduit 5 to supply an air/gas mixture to the burner 3, an exhaust pipe 6 for the combustion fumes produced in the burner 3, and a water circuit 7 for the water to be heated, which is only partially illustrated.
  • the burner 3 is arranged inside the heat exchanger 4 and generates a flame 8 which burns the air/gas mixture supplied by the supply conduit 5; in the heat exchanger 4, the combustion fumes generated by the burner transfer heat to the water flowing in the circuit 7.
  • the burner 3, of a type that is substantially known, is for example essentially cylindrical and has a cylindrical side wall provided with holes (not illustrated) for emitting the air/gas mixture and feeding the flame 8.
  • the heat exchanger 4 is essentially cylindrical in shape and extends along an axis A; the heat exchanger 4 comprises a casing 11 through which the combustion fumes flow, a pipe 12 along which the water in the circuit 7 flows, and a baffle 13 or other equivalent diverting means for directing the combustion fumes along a fixed path, schematically illustrated by the arrow in figure 1 , inside the casing 11.
  • the casing 11 comprises an essentially cylindrical side wall 14 arranged about the axis A and two walls 15, 16 of opposite ends, essentially parallel to one another and perpendicular to the axis A.
  • the wall 15 supports the supply conduit 5 and the burner 3; the wall 16 supports the exhaust pipe 6.
  • the burner 3 extends centrally inside the casing 11 essentially along the axis A and thus coaxially to the heat exchanger 4 and is provided with one end 17 fitted to the wall 15 and one free end 18, opposite the fitted end 17.
  • the pipe 12 is arranged inside the casing 11 and is coiled about the axis A so as to form a succession of adjacent turns 20 arranged so as to be essentially parallel along the axis A in proximity to the side wall 14; the pipe 12 extends along a longitudinal axis C (curved) coiled about the axis A and is provided with a side wall 21, having an outer side surface 22 and an inner side surface 23, and two opposite ends provided with respective fittings 25 for connecting the pipe 12 to the water circuit 7.
  • the coiled pipe 12 delimits inside the casing 11 a radially internal zone 26 and a radially external zone 27 arranged coaxially in relation to one another.
  • the baffle 13 is arranged so as to be essentially perpendicular to the axis A in the casing 11 and specifically in the zone 26; the baffle 13 faces the free end 18 of the burner 3 and is arranged radially inside the pipe 12; the baffle 13 divides the zone 26 into two chambers 28, 29 aligned along the axis A; the chamber 28, adjacent to the wall 15, houses the burner 3 and also acts as a combustion chamber; the chamber 29, adjacent to the wall 16, is connected to the exhaust pipe 6.
  • the cross-section 32 of the pipe 12 (perpendicular to the longitudinal axis C of the pipe 12), which is preferably constant, comprises at least one outwardly concave portion 33 and one outwardly convex portion 34 opposite the concave portion 33.
  • Each turn 20 thus comprises a concave surface portion 35 and a convex surface portion 36 of the surface 22 of the pipe 12, arranged on opposite sides of a central plane P of the turn 20 essentially perpendicular to the axis A.
  • Adjacent turns 20a, 20b, face one another parallel to the axis A so that the concave portion 33 of one turn 20a faces the convex portion 34 of the adjacent turn 20b; thus, the concave surface portion 35 of a turn 20a also faces the convex surface portion 36 of the adjacent turn 20b.
  • the turns 20 are arranged in succession along the axis A and are axially separated by respective gaps 40 defining essentially radial channels 41 through which the combustion fumes flow between the radially internal zone 26 and the radially external zone 27.
  • Each channel 41 delimited by a pair of adjacent turns 20a, 20b extends along a curved and/or non-rectilinear axis and is delimited by the concave surface portion 35 of a turn 20a and by the convex surface portion 36 of the adjacent turn 20b, which are essentially parallel to one another, the concave portion 33 and the convex portion 34 having essentially similar or complementary profiles.
  • the cross-section 32 of the pipe 12 is flattened and/or elongated in an essentially radial direction with respect to the axis A and has a major axis X (essentially perpendicular to the axis A) and a minor axis Y (essentially parallel to the axis A).
  • the concave portion 33 of each turn 20 is essentially arranged along the major axis X and the concave portion 33 and the convex portion 34 of each turn 20 are arranged on opposite sides of the major axis X.
  • Adjacent turns 20a, 20b are shaped and arranged so that there is essentially no direct radial gap between the radially internal zone 26 and the radially external zone 27, that is so that the pipe 12 provides an almost complete shield against direct irradiation between the zone 26 (which houses the burner 3) and the zone 27 (with the side wall 14 of the casing 11).
  • the turns 20 of the pipe 12 are shaped and arranged so that the coiled pipe 12 completely shields the side wall 14 of the casing 11 against the direct irradiation (schematically illustrated by the arrow in figure 3 ) by the flame 8 of the burner 3.
  • the outer surface 22 of the pipe 12 is longitudinally grooved (on all or part of the surface), being provided with a plurality of longitudinal grooves 42 parallel to one another and to the longitudinal axis C of the pipe 12.
  • At least the facing surface portions 35, 36, which delimit the channels 41, of adjacent turns 20 are provided with grooves 42.
  • Adjacent turns 20 are thus provided with respective facing surface portions 35, 36 provided with respective pluralities of opposing longitudinal grooves 42; the grooves 42 of adjacent turns 20 provided on the facing surface portions 35, 36 protrude radially towards one another and may essentially be aligned with respect to one another, or staggered with respect to one another.
  • the grooves 42 may be arranged solely on the facing surface portions 35, 36, and/or on other preferential surface portions of the surface 22, for example surface portions facing the burner 3 and thus facing the axis A, or essentially on the entire surface 22.
  • each projecting part 43 is essentially perpendicular to the surface 22 and the projecting parts 43 are thus arranged radially or in a crown about the axis A on the surface 22.
  • the depth of the grooves 42 is preferably not more than approximately 5 mm.
  • Each groove 42 is delimited by a pair of lateral sides 45, essentially parallel to the longitudinal axis C of the pipe 12; in the example that is illustrated, the sides 45 converge towards a rounded base 46 of the groove 42; it is understood that the shape of the grooves 42 may differ from that described herein and illustrated merely by way of example.
  • the sides 45 could be essentially parallel to one another, and could be essentially flat or even curved; the base 46 could be square-cornered, or even essentially flat.
  • the cross-section of the grooves may be essentially triangular with a square-cornered or rounded vertex, essentially trapezoidal, rectangular or generally quadrangular or polygonal, with curved sides and/or square or rounded corners, etc., or a complex shape optimized to generate turbulence suitable to improve heat exchange efficiency.
  • the inner surface 23 of the pipe 12 is also longitudinally grooved (on all or part of the surface), and is in turn provided with a plurality of longitudinal inner grooves 44 parallel to one another and to the longitudinal axis C of the pipe 12, identical in terms of geometry and dimensions to the grooves 42.
  • the pipe 12 is preferably made of metal, for example aluminium; preferably, but not necessarily, the pipe 12 is manufactured by means of an extrusion process; in this case, the grooves 42 and/or the grooves 44 are most advantageously produced directly during the pipe 12 extrusion process.
  • the boiler 1 provided with the heat exchanger 4 works in essentially the same way as similar boilers.
  • the combustion fumes generated by the burner 3 in the chamber 28 flow from the chamber 28 to the radially external zone 27, between the turns 20 of the pipe 12 through the channels 41 in a radially external direction and transfer heat to the water flowing along the pipe 12; the combustion fumes thus flow past the baffle 13 over the side wall 14 of the casing 11, and then flow back between the turns 20 of the pipe 12 in a radially internal direction through the channels 41, complete the transfer of heat to the water in the pipe 12 and then flow into the exhaust pipe 6.
  • the heat exchanger 4 achieves high heat exchange efficiency, due to the particular geometry of the cross-section 32; in particular, the channels 41 through which the combustion fumes flow are arranged so as to prolong the time for which the combustion fumes remain in contact with the side wall 21 of the pipe 12, and produce dynamic effects that improve heat exchange.
  • the shielding effect against the direct irradiation by the flame 8 on the side wall 14 of the casing 11 also contributes to increasing the efficiency of the heat exchanger 4.
  • Efficiency is further increased due to the presence of the grooves 42 and/or the grooves 44, the function of which is to increase the heat exchange surface and generate surface turbulence.
  • the heat exchanger 4 is both simple and inexpensive to produce, particularly since the pipe 12 can be obtained directly by means of an extrusion process, during which the grooves 42, 44 can also be produced.
  • the shape of the cross-section 32 may differ from that described and illustrated herein purely by way of example, for instance it could be essentially round, oval, essentially quadrangular or polygonal, with rounded edges and/or corners, etc. provided it always has a concave portion 33 and a corresponding convex portion 34.
  • the grooves 42, 44 may also differ in shape, for example they could be triangular with square or rounded vertices, or essentially rectangular or polygonal with square-edged or rounded corners, etc. or complex shapes optimized to generate turbulence in order to improve heat exchange efficiency.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
EP20080159622 2007-07-04 2008-07-03 Heat exchanger for a boiler and gas boiler, in particular a condensation boiler, provided with said heat exchanger Withdrawn EP2012071A2 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
ITMI20071330 ITMI20071330A1 (it) 2007-07-04 2007-07-04 Scambiatore di calore per una caldaia a gas e caldaia a gas, in particolare caldaia a condensazione, provvista di tale scambiatore di calore

Publications (1)

Publication Number Publication Date
EP2012071A2 true EP2012071A2 (en) 2009-01-07

Family

ID=39745662

Family Applications (1)

Application Number Title Priority Date Filing Date
EP20080159622 Withdrawn EP2012071A2 (en) 2007-07-04 2008-07-03 Heat exchanger for a boiler and gas boiler, in particular a condensation boiler, provided with said heat exchanger

Country Status (2)

Country Link
EP (1) EP2012071A2 (it)
IT (1) ITMI20071330A1 (it)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2941609A1 (en) * 2012-11-30 2015-11-11 Carlos Quesada Saborio Tubing element for a heat exchanger means

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2941609A1 (en) * 2012-11-30 2015-11-11 Carlos Quesada Saborio Tubing element for a heat exchanger means

Also Published As

Publication number Publication date
ITMI20071330A1 (it) 2009-01-05

Similar Documents

Publication Publication Date Title
EP1752718B1 (en) Method of producing a heat exchanger
RU2682204C2 (ru) Труба теплообменника и отопительный котел, имеющий такую трубу теплообменника
EP1750070A1 (en) Heat exchanger with finned tube and method of producing the same
US9976772B2 (en) Sectional heat exchanger for use in a heat cell
RU2018130211A (ru) Конденсационный теплообменник, оснащенный теплообменным устройством
US20080186039A1 (en) Heat exchanger with finned tube and method of producing the same
RU2012129345A (ru) Нагревательный прибор для автомобиля
US20080185131A1 (en) Heat exchanger and method of producing the same
EP2012071A2 (en) Heat exchanger for a boiler and gas boiler, in particular a condensation boiler, provided with said heat exchanger
EP2724106B1 (en) Heat exchanger tube set
RU2386905C1 (ru) Теплогенератор
EP2012072A2 (en) Heat exchanger for a gas boiler and gas boiler, in particular a condensation boiler, provided with said heat exchanger
EP2549197A2 (en) A panel used in fluid mechanics
RU184599U1 (ru) Водотрубный котел
EP2884201A1 (en) High-efficiency heat exchanger for boilers and hot air generators
RU2680283C1 (ru) Устройство для нагрева воздуха
KR20030082199A (ko) 열교환 성능이 향상된 난방 및 급탕 가스 보일러
KR101467910B1 (ko) 열교환기
RU200074U1 (ru) Теплообменник для водогрейного котла
RU2467260C2 (ru) Технологический нагреватель
RU195711U1 (ru) Водотрубный котёл
RU2639438C1 (ru) Котел с принудительной циркуляцией
JP2007163006A (ja) 熱吸収用フィンを付けたボイラ
CN110118435B (zh) 一种壁挂炉热交换器
EP3426986B1 (en) Sectional heat exchanger for use in a heat cell

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MT NL NO PL PT RO SE SI SK TR

AX Request for extension of the european patent

Extension state: AL BA MK RS

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: FONDITAL S.P.A.

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20140201