EP0287142B1 - A boiler element - Google Patents

A boiler element Download PDF

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Publication number
EP0287142B1
EP0287142B1 EP88200501A EP88200501A EP0287142B1 EP 0287142 B1 EP0287142 B1 EP 0287142B1 EP 88200501 A EP88200501 A EP 88200501A EP 88200501 A EP88200501 A EP 88200501A EP 0287142 B1 EP0287142 B1 EP 0287142B1
Authority
EP
European Patent Office
Prior art keywords
water
temperature area
boiler
inlet
heat exchange
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.)
Expired - Lifetime
Application number
EP88200501A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0287142A3 (en
EP0287142A2 (en
Inventor
Jan Hubertus Anna Deckers
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.)
Robert Bosch GmbH
Original Assignee
Radson BV
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 Radson BV filed Critical Radson BV
Priority to AT88200501T priority Critical patent/ATE64990T1/de
Publication of EP0287142A2 publication Critical patent/EP0287142A2/en
Publication of EP0287142A3 publication Critical patent/EP0287142A3/en
Application granted granted Critical
Publication of EP0287142B1 publication Critical patent/EP0287142B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • F24H1/38—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water contained in separate elements, e.g. radiator-type element

Definitions

  • This invention relates to a light-metal, one-piece heat exchange element, in particular for a central heating boiler, comprising a substantially flat, box-shaped body through which a water passage extends along a curved path between an inlet and an outlet, flat side walls of the body being provided with protrusions extending into flue gas passages on either side of said body, said flue gas passages having a decreasing sectional area in the direction of flow of the gas.
  • the water passage has a serpentine or zigzag form, with a sectional area decreasing from the inlet in the low gas temperature area to the outlet in the high gas temperature area sufficiently enough (e.g. in the ratio of 2: 1) to ensure that the flow velocity of counter flow supplied water at the outlet is higher than at the inlet.
  • the present invention is based on the insight that in the high gas temperature area, the temperature differential with the heated water is amply sufficient to ensure effective and fast heat transfer.
  • the hot gas will give up the major part of its heat to the heat exchange element in the first half of the gas trajectory.
  • the gas in the second half of the gas trajectory is brought in a heat-exchanging relationship with relatively slowly flowing and moreover relatively cold water, it is possible to strongly cool the gas, and even to bring it to condensation level.
  • the protrusions can be designed as studs arranged according to a pattern of laterally offset rows, with the interspace of the studs decreasing gradually from the high towards the low gas temperature area, e.g. in total in the ratio of 2.5: 1.
  • EP-A-0021 512 discloses, per se, a heat exchanger wherein pins are provided in the flue gas passages in a pattern of laterally offset rows, with the interspace of the pins decreasing gradually from the high to the low temperature area, but not in combination with counter-currently supplied water with the velocity of the discharged hot water being higher than that of the entering cold water.
  • the present invention also concerns a water heating boiler comprising a heat exchange element according to the present invention and a burner, the boiler element according to claim 1 being fittingly enclosed on either side by a substantially U-shaped duct for supplying a combustible gas and air mixture to the top of a perforate burner plate disposed in a burner chamber provided above the boiler element, the bottom of said chamber being in open communication with the flue gas passages enclosed by the body of the boiler element and the inner wall of the gas/air duct.
  • Such a central heating boiler if fitted with a boiler element of outside dimensions in the order of 25 ⁇ 15 ⁇ 20 (H ⁇ W ⁇ D), a water passage decreasing stepwise in cross section from about 10 cm2 at the inlet to about 5 cm2 at the outlet, and on either side studs having on an average a cross-sectional area of 1 cm2 and, in the high gas temperature area, a length of 23 mm and an interspace of 7 mm and in the low temperature area a length of 15 mm and an interspace of 5 mm, can provide per kg of aluminium a power output of about 3 KW, which is very high for such a small and light-weight boiler.
  • a heat-resistant burner i.e. one having a perforate plate made e.g. from ceramic material, to the rear of which the gas and air mixture is supplied under pressure, and which, at the front, functions as a burner bed. This allows to obtain a flue gas temperature exceeding 1,200°C.
  • the boiler element cast in one piece from light metal, such a aluminium alloy, has a flat, box-shaped body 1 with a water inlet nipple 2 and a water discharge nipple 3 in one of the end walls.
  • closable studs 4 which serve for removing the casting core.
  • a water passage 5 extends in serpentine fashion, whose sectional area decreases stepwise down to a ratio of 2: 1, see Figs. 1 and 3.
  • finger-shaped protusions which in the embodiment shown, have the form of four-sided studs 6, which taper slightly for ease of release from the mould. Studs 6 are arranged in a pattern of laterally offset horizontal rows (see Fig. 2), which are placed more closely together at the bottom than at the top. As shown in Fig. 1, studs 6 are also shorter at the bottom of the body 1 than at the top.
  • a chamber 10 containing a perforate burner plate B.
  • Fig. 4 shows a gas supply device 11 and a blower 12 for the forced supply of a combustible gas and air mixture through the U-shaped duct 8 to the top of burner chamber 10.
  • flue gases are generated in burner chamber 10 which have a very high temperature of about 1,200°C, and which are forcibly moved downwardly through the flue gas passages 9 and are discharged through the bottom of the boiler element, cooled at 70-80°C or lower.
  • burner chamber 10 which have a very high temperature of about 1,200°C, and which are forcibly moved downwardly through the flue gas passages 9 and are discharged through the bottom of the boiler element, cooled at 70-80°C or lower.
  • body 1 Through their passage in the labyrinthine trajectory between studs 6, they give up heat, directly to body 1 and indirectly through studs 6 with which they are brought into close contact due to vortexes produced thereby.
  • body 1 Through body 1 the heat absorbed is transferred to the water flowing in passage 5.
  • the heat transfer or thermal conduction per unit of surface area is determined by the temperature differential and the time.
  • the cold water in the lower, low-temperature area of the boiler element flows much more slowly than in the upper, high gas temperature area. It is true that in the lower, low gas temperature area, the heated surface area has been reduced on the gas side by narrowing the flue gas passages 9, but because the studs are more closely spaced, the flue gas, whose volume has been reduced due to drop in temperature, intensely swirled in the narrow passages between studs 6 and hence forced into close contact with the stud sides and with the portions of the body walls 1a, 1b intermediate studs 6, so that the flue gases have an opportunity of optimally giving off their heat.
  • baffles 13-17 form a serpentine or zigzag trajectory 5 in the hollow inner space of body 1, which trajectory becomes narrower at each bend and, in the embodiment shown, is halved in five steps so that, with a constant flow rate, the output velocity at 3 is about double the input velocity at 2.
  • the water is heated during its passage through body 1 and thereby expands, the velocity at outlet 3 will be more than double the velocity at inlet 2.
  • An essential feature of the present invention is that in the portion of the heat exchanger where relatively cool flue gases have to give off their (residual) heat to cold inflowing water, the water passes at a relatively low velocity and the flue gases are forced to make frequent and intensively contacts, with the heated surface, while in the high gas temperature area, a large contact surface area is offered to the inflowing gases of very high temperature.
  • the large temperature differential in the order of 1,100°C) enables a fast heat transfer to the water, so that this can be discharged relatively quickly.

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)
  • Air Supply (AREA)
  • Steam Or Hot-Water Central Heating Systems (AREA)
EP88200501A 1987-03-18 1988-03-18 A boiler element Expired - Lifetime EP0287142B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT88200501T ATE64990T1 (de) 1987-03-18 1988-03-18 Kesselelement.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL8700641 1987-03-18
NL8700641A NL8700641A (nl) 1987-03-18 1987-03-18 Ketelelement.

Publications (3)

Publication Number Publication Date
EP0287142A2 EP0287142A2 (en) 1988-10-19
EP0287142A3 EP0287142A3 (en) 1988-12-07
EP0287142B1 true EP0287142B1 (en) 1991-07-03

Family

ID=19849727

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88200501A Expired - Lifetime EP0287142B1 (en) 1987-03-18 1988-03-18 A boiler element

Country Status (4)

Country Link
EP (1) EP0287142B1 (nl)
AT (1) ATE64990T1 (nl)
DE (1) DE3863461D1 (nl)
NL (1) NL8700641A (nl)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1450114A1 (de) 2003-02-18 2004-08-25 Robert Bosch Gmbh Wärmetauscher mit einem strömungsoptimierten wärmeaufnehmenden Strömungskanal, insbesondere für ein Heizgerät
DE102007057062A1 (de) 2007-11-27 2009-05-28 Robert Bosch Gmbh Wärmetauscher, insbesondere für ein Heizgerät

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE68926202T3 (de) * 1988-09-14 2002-05-16 Showa Denko Kk Kondensator
NL9300100A (nl) * 1993-01-19 1994-08-16 Radson Alutherm Nv Drie-weg combi-ketel.
DE202004018968U1 (de) * 2004-12-08 2005-02-10 Bbt Thermotechnik Gmbh Wärmetauscher
DE102007060508A1 (de) 2007-12-15 2009-06-18 Robert Bosch Gmbh Wärmetauscher für ein Heizgerät
WO2019008005A1 (en) * 2017-07-07 2019-01-10 Bekaert Combustion Technology B.V. COUPLED ELEMENT FOR HEAT EXCHANGER

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1425473A (en) * 1972-01-27 1976-02-18 Applegate G Sectional heat exchangers
IT1032836B (it) * 1975-05-09 1979-06-20 Finterm Spa Elemento scambiature per caldaie
US4201263A (en) * 1978-09-19 1980-05-06 Anderson James H Refrigerant evaporator
NL7904829A (nl) * 1979-06-20 1980-12-23 Rheem Bv Warmtewisselaar voor een cv-ketel of dergelijke.
NL8102695A (nl) * 1981-06-03 1983-01-03 Dru Bv Hoogrendementsketel zonder ventilator.

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1450114A1 (de) 2003-02-18 2004-08-25 Robert Bosch Gmbh Wärmetauscher mit einem strömungsoptimierten wärmeaufnehmenden Strömungskanal, insbesondere für ein Heizgerät
DE10306699A1 (de) * 2003-02-18 2004-09-02 Robert Bosch Gmbh Wärmetauscher mit einem strömungsoptimierten wärmeaufnehmenden Strömungskanal, insbesondere für ein Heizgerät
DE102007057062A1 (de) 2007-11-27 2009-05-28 Robert Bosch Gmbh Wärmetauscher, insbesondere für ein Heizgerät
EP2065656A2 (de) 2007-11-27 2009-06-03 Robert Bosch GmbH Wärmetauscher

Also Published As

Publication number Publication date
DE3863461D1 (de) 1991-08-08
NL8700641A (nl) 1988-10-17
EP0287142A3 (en) 1988-12-07
EP0287142A2 (en) 1988-10-19
ATE64990T1 (de) 1991-07-15

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