US3555845A - Forced-flow evaporator for compression refrigeration equipment - Google Patents

Forced-flow evaporator for compression refrigeration equipment Download PDF

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Publication number
US3555845A
US3555845A US757648A US3555845DA US3555845A US 3555845 A US3555845 A US 3555845A US 757648 A US757648 A US 757648A US 3555845D A US3555845D A US 3555845DA US 3555845 A US3555845 A US 3555845A
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evaporator
liquid
forced
wall
gauze
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US757648A
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English (en)
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Zbigniew Ryszard Huelle
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Danfoss AS
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Danfoss AS
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Priority claimed from DE19671601023 external-priority patent/DE1601023C3/de
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B39/00—Evaporators; Condensers
    • F25B39/02—Evaporators

Definitions

  • FORCED-FLOW EVAPORATOR FOR COMPRESSION REFRIGERATION EQUIPMENT Filed Sept. 5, 1968 United States Patent 3,555,845 FORCED-FLOW EVAPORATOR FOR COMPRESSION REFRIGERATION EQUIPMENT Zbigniew Ryszard Huelle, Sonderborg, Denmark, assignor to Danfoss A/S, Nordborg, Denmark, a company of Denmark Filed Sept. 5, 1968, Ser. No. 757,648 Claims priority, application Ggrmany, Sept. 6, 1967,
  • liquid refrigerant In refrigerating equipment of this kind liquid refrigerant must be prevented from passing from the evaporator into the compressor or its case, since otherwise trouble could occur.
  • the temperature sensor determines that the evaporation temperature, rather than the superheating temperature, obtains at the point of measurement, i.e. that liquid refrigerant has still to be evaporated, the flow of refrigerant must be throttled or interrupted.
  • the element that influences the flow of refrigerant must, how ever, respond if a prescribed superheating temperature is not reached, and should not respond only when the evaporating temperature is attained.
  • a tubular surface is provided with a longitudinal groove and with closely spaced circumferential channels of such size that liquid can be drawn into them by capillary action.
  • the surface of the evaporator tube is intended to be uniformly wetted even if the liquid refrigerant, subjected to no pressure, drips on to it only at one or a few places.
  • the object of the present invention is to provide a forced-flow evaporator for compression refrigerating equipment, the control system of which responds to a small excess-heat temperature and wherein it is nevertheless ensured that no fluid refrigerant reaches the compressor.
  • this object is achieved by providing at least part of the wall of the evaporator passage with means for increasing wetting by liquid refrigerant, which means, however, leave the major part of the cross-section of the passage open.
  • vapour is formed which flows through the piping together with the liquid.
  • the liquid proportion progressively decreases until an evaporation end-point is reached beyond which only vapour is present. It is known that even in the case of constant flow, the evaporation end-point moves to and fro, in periods of up to 3 sec., over a considerable length of the evaporator piping, e.g., 50 cm.
  • the invention is based upon the knowledge that the excess-heat temperature, hitherto required for reasons of safety, can be considerably reduced if the migration of the evaporation end-point along the evaporator piping can be curtailed.
  • the means for increasing the wetting should be located at least in the zone near the point at which evaporation ends, i.e., in the portion in front of the sensor. They need only extend over roughly the second half of the length of the evaporator, for example. In many cases, particularly where the system is to be fitted at a later stage, it is of advantage if the main part of the evaporator is provided with an added pipe, to the end of which the sensor is fitted, and the means for increasing the wetting extend only along this pipe.
  • the means for reinforcing the wetting action take the form of a capillary system.
  • the liquid is rapidly spread over a large surface of the wall of the passage by the capillary system and is efiiciently held by surface tension.
  • a particularly simple form of the invention is characterized by an inserted wall, containing orifices and extending parallel with the wall of the passage at a short distance therefrom and supported thereon, so that a space is created between the inserted wall and the passage wall, this forming the capillary system. In this way, a relatively thick layer of liquid is spread over and retained on the wall of the passage.
  • the inserted wall and its supporting means are preferably formed from a gauze fabric which lies on the passage wall, e.g. the wall of the tube.
  • a gauze material can be readily inserted into a tube. Since the liquid can flow on both sides of the gauze, particularly good wetting of the wall of the passage results. The cross-section of the passage is not, however, interfered with to any considerable extent at the centre.
  • the wire gauze can be readily provided with a capillary mesh so that liquid is retained therein in a particularly efficient manner.
  • the gauze fabric By compressing the gap, the gauze fabric can be readily introduced into the flow-passage of the evaporators.
  • the gap should be located at the bottom of the cross-section of the passage, so that the oil can drain off.
  • FIG. 1 shows, schematically, a first embodiment of the invention
  • FIG. 2 is a cross-section through the evaporator tube in the region of the line A-A, and
  • FIG. 3 is a schematic illustration of another embodiment.
  • FIG. 1 shows a normal tubular evaporator, which consists of a tube 1, at the front of which is fitted a thermostatic expansion valve 2 and at the outlet of which is fitted a temperature sensor 3.
  • a thermostatic expansion valve 2 By means of this sensor and with the help of the expansion valve 2 the flow of refrigerant is so adjusted that, whatever the circumstances, all the liquid refrigerant is evaporated at the point 4.
  • the point at which evaporation ends ranges over quite a considerable length of the evaporator, for example between the points 4 and 5.
  • the thermostatic system 2 and 3 should not respond, since when the supply of refrigerant is correspondingly increased, the end point 4 moves beyond the sensor 3 and liquid refrigerant would thus reach the compressor.
  • a cylindrical gauze element 6 is inserted in the smooth-walled evaporator tube 1.
  • this gauze extends over approximately the second half of the length of the evaporator, i.e. over about 40-60% of the length.
  • the point at which evaporation ends is restricted to moving backwards and forwards over a very much smaller distance, for example, between the points 4 and 7.
  • the possible overheating between point 7 and the feeler 3 is considerably smaller than hitherto. Consequently, the thermostatic system may respond at a lower excess-heat temperature, without there being any danger of the liquid refrigerant reaching the compressor.
  • FIG. 2 shows the cylindrical gauze element 6 inserted in the evaporator tube 1, the wires 8 of this element also forming supports 9 (indicated schematically).
  • the gauze contains a longitudinal slot 10 which, on the one hand, can serve for the discharge of deposited oil and, on the other hand, enables the gauze to be easily pushed into the tube 1 in front of the bend of this tube.
  • the gauze lies around the smooth inner wall of the tube 1 and forms a space 11 which is of such size that refrigerant can be retained therein by capillary action or surface tension.
  • the refrigerant is, of course, driven along the tube by the compression pressure.
  • the layer of liquid refrigerant flowing in this area wets the wall of the passage very efliciently, and this contributes to a reduction in the fluctuation of the point at which evaporation terminates. Due to this wetting, the mobility of the ring of liquid is reduced. Furthermore, the heat-transfer is improved and evaporation is thus accelerated. This acceleration of the evaporation also reduces the fluctuations in the point at which evaporation ends, since the small quantity of liquid finally remaining is evaporated over a shorter portion of the tube.
  • FIG. 3 there is shown a normal plate evaporator 12 in which the evaporator pipe 13 has been made by the roll-bond process.
  • a tube 14 is added to the plate evaporator 12, a gauze 15, equivalent to the gauze 6 shown in FIG. 2, being inserted in this tube.
  • the sensor is then fitted at the end of the tube 14.
  • the mesh-size of the gauze will depend upon the particular circumstances. Mesh-size number (DIN 4189), for example, has proved to be particularly suitable.
  • a capillary system can also be obtained by machining the inside wall of the pipe; the insertion of a sock-like gauze element is of advantage, however, both for reasons of simpler manufacture and for reasons of its superior functioning.
  • a forced-flow evaporator assembly for compression type refrigerating equipment comprising, tubing means having inlet and outlet ends, valve means at said inlet end and temperature sensing means at said outlet end for controlling said valve means, liquid absorption means in said tubing means comprising a capillary system for absorbing liquid refrigerant, said liquid absorption means occupying less than one-half the linear length of said tubing means, said tubing means defining an internal wall surface, said liquid absorption means comprising a perforated wall internally spaced from said wall surface to define an annular space between said wall surface and said wall, said annular space forming a portion of said capillary system.
  • a forced-flow evaporator assembly according to claim 1 wherein said perforated wall defines a longitudinally extending channel.
  • a forced-flow evaporator assembly according to claim 1 wherein said liquid absorption means is disposed between said temperature sensing means and said valve means and in juxtaposition to said temperature sensing means.
  • a forced-flow evaporator assembly according to claim 5 wherein about one-half the length of said tubing,

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
  • Temperature-Responsive Valves (AREA)
  • Separation By Low-Temperature Treatments (AREA)
US757648A 1967-09-06 1968-09-05 Forced-flow evaporator for compression refrigeration equipment Expired - Lifetime US3555845A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19671601023 DE1601023C3 (de) 1967-09-06 1967-09-06 Zwangsdurchlauf-Verdampfer für Kompressions-Kälteanlagen

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US3555845A true US3555845A (en) 1971-01-19

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US757648A Expired - Lifetime US3555845A (en) 1967-09-06 1968-09-05 Forced-flow evaporator for compression refrigeration equipment

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US (1) US3555845A (enrdf_load_stackoverflow)
JP (1) JPS4821982B1 (enrdf_load_stackoverflow)
AT (1) AT289164B (enrdf_load_stackoverflow)
DK (1) DK127136B (enrdf_load_stackoverflow)
ES (1) ES357801A1 (enrdf_load_stackoverflow)
FR (1) FR1599763A (enrdf_load_stackoverflow)
GB (1) GB1233924A (enrdf_load_stackoverflow)
NO (1) NO123736B (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4074753A (en) * 1975-01-02 1978-02-21 Borg-Warner Corporation Heat transfer in pool boiling
US4213307A (en) * 1978-11-13 1980-07-22 Westinghouse Electric Corp. Oil separation and return system for centrifugal refrigerant compressors
US5040380A (en) * 1988-08-04 1991-08-20 Super S.E.E.R. Systems Inc. Method and apparatus for the sensing of refrigerant temperatures and the control of refrigerant loading
US5052190A (en) * 1988-08-04 1991-10-01 Super S.E.E.R. Systems Inc. Apparatus for the sensing of refrigerant temperatures and the control of refrigerant loading
US20100126213A1 (en) * 2007-06-15 2010-05-27 Tsinghua University Liquid-Vapor Separating Method and a Liquid-Vapor Separating Type Evaporator

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2190168C2 (ru) * 2000-11-21 2002-09-27 Закрытое акционерное общество "ОРЛЭКС" Испаритель холодильного агрегата
DE20314411U1 (de) * 2003-09-15 2005-01-20 Viessmann Werke Gmbh & Co Kg Apparat zur Erzeugung von Wasserstoff

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4074753A (en) * 1975-01-02 1978-02-21 Borg-Warner Corporation Heat transfer in pool boiling
US4213307A (en) * 1978-11-13 1980-07-22 Westinghouse Electric Corp. Oil separation and return system for centrifugal refrigerant compressors
US5040380A (en) * 1988-08-04 1991-08-20 Super S.E.E.R. Systems Inc. Method and apparatus for the sensing of refrigerant temperatures and the control of refrigerant loading
US5052190A (en) * 1988-08-04 1991-10-01 Super S.E.E.R. Systems Inc. Apparatus for the sensing of refrigerant temperatures and the control of refrigerant loading
US20100126213A1 (en) * 2007-06-15 2010-05-27 Tsinghua University Liquid-Vapor Separating Method and a Liquid-Vapor Separating Type Evaporator

Also Published As

Publication number Publication date
GB1233924A (enrdf_load_stackoverflow) 1971-06-03
ES357801A1 (es) 1970-04-01
DK127136B (da) 1973-09-24
AT289164B (de) 1971-04-13
JPS4821982B1 (enrdf_load_stackoverflow) 1973-07-03
FR1599763A (enrdf_load_stackoverflow) 1970-07-20
NO123736B (enrdf_load_stackoverflow) 1972-01-03

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