US3886997A - Method of operating a heat exchanger - Google Patents

Method of operating a heat exchanger Download PDF

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Publication number
US3886997A
US3886997A US404680A US40468073A US3886997A US 3886997 A US3886997 A US 3886997A US 404680 A US404680 A US 404680A US 40468073 A US40468073 A US 40468073A US 3886997 A US3886997 A US 3886997A
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United States
Prior art keywords
heat
exchange fluid
solids
liquid heat
heat exchanger
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Expired - Lifetime
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US404680A
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English (en)
Inventor
Ludolf Plass
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GEA Group AG
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Metallgesellschaft AG
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Publication date
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Publication of US3886997A publication Critical patent/US3886997A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D13/00—Heat-exchange apparatus using a fluidised bed

Definitions

  • ABSTRACT A method of operating a heat exchanger in which a liquid medium is passed into heat-exchanging relationship with a heat-exchanger wall surface, wherein inert solid particles in a particle size range of l0 to 150 microns are added to the liquid medium in an amount of 0.5 to 20% by volume to form a suspension in which the Reynolds number Re LTD/v is 10,000 to 70,000 for a diameter D of l cm.
  • This invention relates to a method of operating closed heat exchangers which are supplied with liquid heat-exchange fluids.
  • the rate at which heat is transferred from a given liquid heat-exchange fluid to a wall and vice versa depends substantially on the velocity of the fluid and on the area and nature of the wall surface in contact with the heat-exchange fluid.
  • the heat-transfer rate can be increased by an increase of the velocity of the heat exchange fluid, an increase of the area of the wall (eg by the incorporation of baffles) and by a toughening of the wall surface.
  • Each of these measures gives rise to a rapidly increasing pressure loss. For instance, an increase of the velocity of the fluid will result in an increase of the pressure loss which is almost twice as large as the increase of the heat-transfer rate so that the increase of the velocity of the fluid is limited by economic considerations.
  • the incorporation of baffles and the roughening of the heat-exchange wall surface also result in high pressure losses.
  • the method of operating closed heat exchangers supplied with liquid heat exchange fluids according to the invention provides that inert solids having an average particle diameter in the range of l-l50 microns are incorporated in the heat exchange fluid in an amount of 0.5% by volume, and the average velocity of the suspension is adjusted to correspond to a Reynolds number in the range of l0,000-70,000 based on a pipe diameter of l centimeter.
  • Reynolds number is defined as Re H D/v where E is the average velocity in the main direction of flow in meters per second, D is a length, in meters. which de fines the cross-sections of the passages of the heat exchanger which are traversed, e.g., the pipe diameter, and v is the kinematic viscosity in m sec". For this reason the dimensions of the passages of the heat exchanger must be taken into account in selecting the Reynolds number range which meets the requirements of the invention. As applied to tubular passages having a diameter which differs from the unit value of l centimeter. the Reynolds numbers must be linearly changed accordingly. Where tubes are used which are for example 2 or 3 centimeters in diameter, the Reynolds number must lie between 20,000 and l40.000 or between 30,000 and 210,000, respectively.
  • the increase of the heat-transfer rate will be particularly large if, according to a preferred feature of the invention, the inert solids incorporated in the heatexchange fluid have an average particle diameter of 10-50 microns and are used in an amount of l6% by volume, particularly 2.56% by volume.
  • the solids to be added to the liquid heat-exchange fluid should suitably be of medium hardness. Excessively high hardness could result in damage to the wall surface of the heat exchanger. An insufficiently high hardness could result in a progressively increasing reduction of the particle size of the added solids.
  • Particularly suitable solids are those having a density of more than 1 gram per cubic centimeter, such as sand, ore dust, and ground slag.
  • Suitable heat-exchange fluids for the purposes of the invention are water, aqueous solutions, e.g. of acids, bases, and salts, or organic solvents, such as diphenyl and mineral oil, provided that the viscosity does not exceed ten times that of water at the temperatures at which the fluid is used
  • the method according to the invention can be used in virtually all closed heat exchangers. These include, double-tube heat exchangers, annular-gap heat exchangers, plate heat exchangers and spiral heat exchangers. Particularly suitable are the heat exchangers which have heating or cooling passages that are free from baffles. The passages may have any desired crosssection.
  • the heat-exchange fluid flowing through the heat exchangers may be conducted in a closed or open cycle.
  • An open cycle will be obtained if the heat exchange fluid is partly evaporated by being subjected to a pressure relief when it has flown through the heat exchanger.
  • FIGS. 1 and 2 are graphs illustrating the dependence of the heat-transfer rate upon the proportion of particles in the liquid medium
  • FIGS. 3-5 are graphs illustrating the dependence of the heat-transfer rate upon the Reynolds number of the suspension.
  • FIG. 6 is a diagram of a heat-exchanger system embodying the invention.
  • FIG. 6 An example of a heat-exchange system according to the present invention has been illustrated in FIG. 6.
  • the tube-bundle heat exchanger 10 has a pair of tube sheets 11, 12 bridged by the tubes 13 from which the first heat-exchange liquid is drawn at chamber 14 and fed by pipe 16 to a pump 17. Particles may be added to the liquid from a hopper 18 by a metering device 19.
  • the suspension. homogenized by the pump 17, is passed through a heat source 20 and is supplied by pipe 21 to the chamber whence the liquid traverses the tubes 13 in a closed system.
  • the other heatexchange liquid is drawn from a reservoir 27 by a pump 26 and receives particles from a hopper 28 by a metering device 29.
  • the suspension is delivered by a pipe 25 to the inlet 22 of the heatexchange space around the tubes 13 and, having been heated, passes through outlet 23 into a heat consumer 24. If the latter evaporates the second liquid, the particles are returned to the hopper 28 as represented at 30.
  • FIGS. 1 and 2 show sets of curves which indicate the change of the heat transfer rate in percent in dependence on the amount of added solids in per cent by volume for given average particle diameters and Reynolds numbers (ReW). 1n the experiments represented in FIGS. 1 and 2, the tested systems had Reynolds numbers of 88,000 and 164,000, respectively.
  • the inert solids consisted of quartz sand which had average particle diameters of 12, 25, 40, 70 and l microns, respectively.
  • FIGS. 3, 4, and 5 indicate the change of the heat transfer rate in dependence on the solids content for Reynolds numbers of 88,000, ll3,000, l40,000. and 164,000 for solids having average particle diameters dp of 12, 40, and 70 microns, respectively.
  • the average velocities of the heat exchange fluid (1.5, 2.0, 2.5, 3.0 meters per second) are stated beside the Reynolds numbers.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
  • Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)
US404680A 1972-10-06 1973-10-09 Method of operating a heat exchanger Expired - Lifetime US3886997A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19722248991 DE2248991A1 (de) 1972-10-06 1972-10-06 Verfahren zum betrieb von waermeaustauschvorrichtungen

Publications (1)

Publication Number Publication Date
US3886997A true US3886997A (en) 1975-06-03

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US404680A Expired - Lifetime US3886997A (en) 1972-10-06 1973-10-09 Method of operating a heat exchanger

Country Status (6)

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US (1) US3886997A (cs)
CA (1) CA977332A (cs)
DE (1) DE2248991A1 (cs)
FR (1) FR2202272B1 (cs)
GB (1) GB1425104A (cs)
IT (1) IT995563B (cs)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001074721A3 (en) * 2000-03-31 2002-02-21 Biomass Conversions L L C Improved desalination of ocean water
US20090032387A1 (en) * 2000-03-21 2009-02-05 Biomass Conversions Llc Desalination of ocean water
JP2012531501A (ja) * 2009-06-30 2012-12-10 オムヤ・デベロツプメント・アー・ゲー 冷却剤

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3301764A1 (de) * 1983-01-20 1984-10-31 Griwo-Technik Grimm & Wolf, 6400 Fulda Zusaetze von organischen und anorganischen stoffen als schwebstoffe in waermetraegerfluessigkeiten zur erhoehung des wirkungsgrades bei der absorption, gewinnung, umwandlung oder austausch von energien

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3127936A (en) * 1957-07-26 1964-04-07 Svenska Skifferolje Ab Method of in situ heating of subsurface preferably fuel containing deposits
US3596713A (en) * 1969-01-27 1971-08-03 Astro Dynamics Inc Liquid-solid heat transport system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3127936A (en) * 1957-07-26 1964-04-07 Svenska Skifferolje Ab Method of in situ heating of subsurface preferably fuel containing deposits
US3596713A (en) * 1969-01-27 1971-08-03 Astro Dynamics Inc Liquid-solid heat transport system

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090032387A1 (en) * 2000-03-21 2009-02-05 Biomass Conversions Llc Desalination of ocean water
WO2001074721A3 (en) * 2000-03-31 2002-02-21 Biomass Conversions L L C Improved desalination of ocean water
AU2001249750B2 (en) * 2000-03-31 2006-05-25 Biomass Conversions, L.L.C. Improved desalination of ocean water
KR100808303B1 (ko) * 2000-03-31 2008-02-27 바이오메스 컨버션스 엘.엘.씨. 물의 증발을 향상시키기 위한 방법 및 장치
JP2012531501A (ja) * 2009-06-30 2012-12-10 オムヤ・デベロツプメント・アー・ゲー 冷却剤
US9080090B2 (en) 2009-06-30 2015-07-14 Omya International Ag Specific fluid for converting light radiation to heat

Also Published As

Publication number Publication date
CA977332A (en) 1975-11-04
FR2202272A1 (cs) 1974-05-03
DE2248991A1 (de) 1974-04-11
GB1425104A (en) 1976-02-18
FR2202272B1 (cs) 1976-10-01
IT995563B (it) 1975-11-20

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