EP0486758A1 - Appareil frigorifique pour des comptoirs frigorifiques à basse température, en particulier pour des produits congelés et surgelés - Google Patents

Appareil frigorifique pour des comptoirs frigorifiques à basse température, en particulier pour des produits congelés et surgelés Download PDF

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Publication number
EP0486758A1
EP0486758A1 EP91110117A EP91110117A EP0486758A1 EP 0486758 A1 EP0486758 A1 EP 0486758A1 EP 91110117 A EP91110117 A EP 91110117A EP 91110117 A EP91110117 A EP 91110117A EP 0486758 A1 EP0486758 A1 EP 0486758A1
Authority
EP
European Patent Office
Prior art keywords
circuit
condenser
heat exchanger
refrigerating apparatus
frozen
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Withdrawn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
EP91110117A
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German (de)
English (en)
Inventor
Giuseppe Casanova
Domenico Mantovani
Luigi Vanin
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.)
Costan SpA
Original Assignee
Costan 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 Costan SpA filed Critical Costan SpA
Publication of EP0486758A1 publication Critical patent/EP0486758A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F25B7/00—Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit

Definitions

  • This invention relates to a refrigerating apparatus for low-temperature refrigerated counters, particularly counters for frozen and deep-frozen products.
  • a most widely used refrigerating fluid in refrigerating systems for temperatures suiting the preservation of frozen or deep-frozen food is a mixture of isomers of chloro-fluorocarbons available commercially under the trade name of Freon R502.
  • Freon R502 is preferred on account of some thermodynamic features thereof. Specifically, it can withstand large pressure fluctuations, as are required to reach the low evaporation temperatures typical of display counters for deep-frozen food, without involving excessive end-of-compression temperatures. For instance, end-of-compression temperatures on the order of 180-200°C are met which do not affect the life span of the compressor equipping the refrigeration circuit.
  • Freon R502 due to it tending to combine chemically with ozone, is regarded as highly hazardous for the environment. In order to restrict this hazard, another mixture, called Freon R22, is preferred.
  • Freon R22 is less suited to high compressions from the thermodynamic standpoint, it producing, for example in traditional systems and for the same performance level as Freon R502, excessively high end-of-compression temperatures (around 230-240°C) for an acceptable life span of the compressor.
  • a first approach provides for the splitting of the target pressure fluctuation over a number of serially connected compressors using a technique of so-called multi-stage compression.
  • Another approach provides for the distribution of the target temperature fluctuation between the refrigerated space and the outside in a number of ranges each controlled by a respective refrigeration circuit.
  • the circuits are operated at increasing temperature ranges and are cascade coupled thermodynamically by means of common heat exchangers wherein the refrigerating fluid of one circuit is condensed to a temperature close to the evaporation temperature of the other cascade-connected circuit.
  • the technical problem addressed by this invention is that of fabricating refrigerated display counters adapted to preserve frozen and deep-frozen products, being cooled by a refrigerating apparatus which is conceived structurally and functionally to overcome the drawbacks with which the cited prior art is beset.
  • a refrigerating apparatus for refrigerated counters characterized in that it comprises at least first and second refrigeration circuits cascade connected to each other through a common heat exchanger, each said circuit including at least one electric compressor of the sealed type.
  • the invention stands, in a first and more general expression thereof, on the use of sealed compressors in cascade-connected circuits filled with fluids which have similar physical properties to those of Freon R22.
  • Vulnerability at the efficiency level of the apparatus may be further fought by coupling the first circuit in the cascade (in thermal contact with the refrigerated counter) both to the next circuit in the cascade and directly to the environment by means of an additional condenser.
  • FIG. 1 a refrigerating apparatus according to the invention, intended for cooling a refrigerated counter schematically shown at 2 and only partly shown in Figure 2.
  • denoted by 23 is a counter insulating structure which surrounds a vat 24 bordering the refrigerated space devoted to preserving the products.
  • the apparatus 1 comprises first, second, and third refrigeration circuits, respectively indicated at 3, 4 and 5.
  • the first circuit 3 comprises, serially connected together, a compressor 6 of the sealed type, a condenser 7 of the coil-in-air type, and a de-watering filter 8, from which there branch off two capillaries 9a and 9b in parallel, each supplying a respective evaporator 10a,b.
  • the evaporators 10a,b form each a part of a respective heat exchanger, generally shown at 11a,b, wherethrough the first circuit 3 is cascade connected to the second and third circuits 4, 5, respectively.
  • the heat exchangers 11a,b are thermally insulated externally using the same insulating structure 23 as the counter 2 in which they are embedded.
  • the second and third circuits 4, 5 form the low-pressure circuit portion of the apparatus 1 relatively to the comparatively high-pressure portion represented by the first circuit 3. They are cascade connected to the first circuit 3 through their respective heat exchangers 11a,b and are substantially identical with each other. Accordingly, only one of them will be described in detail, similar parts of the other being denoted by the same reference numerals with a suffix "a" for the second circuit and a suffix "b" for the third.
  • the second circuit comprises a sealed compressor 18a, a main condenser 12a, and an auxiliary condenser 13a wherebetween a de-watering filter 14a intervenes along with a capillary 15a, followed by first and second evaporators, respectively indicated at 16a and 17a.
  • the main condenser 12a is defined by an annular chamber of the heat exchanger 11a formed between the outer skirt of the evaporator 10a of the first circuit and a tubular conduit 19a extending coaxially outside it.
  • the auxiliary condenser 13a comprises a coil-in-air heat exchanger integral with the condenser 7 and using the same fin formation and the same cooling fans 22. Relatively to such fans and the airflow generated thereby, the condensers 13a,b locate downstream from the condenser 7 of the first circuit.
  • the first evaporator 16a comprises a tubular coil partway embedded in the insulating structure 23 of the counter 2 and being in heat transfer contact with the vat 24. Accordingly, it provides heat transfer mainly by conduction with the preserved products.
  • the second evaporator 17a is suspended in the space to be refrigerated and mainly intended for convective heat transfer. It is for this reason that it comprises a finned heat exchanger.
  • the steady state operation of the refrigerating apparatus is as follows.
  • the three refrigeration circuits 3, 4 and 5 are passed through by a refrigerating fluid such as Freon R 22 flowing in the direction of the arrows. That fluid is compressed, in the first circuit 3, by the compressor 6 from a pressure P1, whose value is related to the evaporation temperature, to a pressure P2 related to the condensation temperature.
  • the end-of-compression temperature reached by the refrigerating fluid is related to the pressure fluctuation P1-P2, and as such, it can be held within acceptable values for an adequate service life of the compressor 6.
  • the compressed and condensed refrigerating fluid is directed to its respective heat exchangers 11a,b through the capillaries 9a,b.
  • the use of two separate capillaries connected in parallel is preferred because it has been found that this solution provide better balance of the thermal load on the low-pressure circuits.
  • the heat exchangers 11a,b are shared by the low-pressure circuit portion and the high-pressure portion of the apparatus 1, wherefor they perform the condenser and evaporator functions, respectively.
  • the refrigerating fluid compressed by the compressors 18a,b will be condensed at a lower temperature than room temperature having a value close to the evaporation temperature in the evaporator of the first circuit 3.
  • auxiliary condensers 13a,b bear little influence at this stage of the apparatus steady state operation, since the end-of-compression temperature reached by the refrigerating fluid at the outlet of the compressors 18a,b is comparatively close to the average temperature of air at the outlet of the condenser 7.
  • Such auxiliary condensers operate instead at full capacity during the starting transient of the apparatus, when the three circuits all operate at a starting temperature which is close to room temperature.
  • auxiliary condensers serve to provide, during this starting transient of the apparatus, a further means of dissipating heat as necessary to accommodate this temporary loss of efficiency.
  • this apparatus can ensure good refrigerating efficiency accompanied by adequate life of its components and improved environmental safeguard. Furthermore, the apparatus is suited to such widely used articles as refrigerated display counters.
  • the proposed configuration affords appreciable savings in space, thereby the apparatus can find room beneath the insulating structure which borders the vat of a refrigerated counter. Contributive to such space savings is the embedding of the heat exchangers which interconnect thermally the low- and high-pressure circuit portions in said insulating structure. This has the added advantage of providing optimum insulation for said heat exchangers at no cost.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Confectionery (AREA)
  • Devices That Are Associated With Refrigeration Equipment (AREA)
EP91110117A 1990-11-22 1991-06-20 Appareil frigorifique pour des comptoirs frigorifiques à basse température, en particulier pour des produits congelés et surgelés Withdrawn EP0486758A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT4173390 1990-11-22
IT04173390A IT1243299B (it) 1990-11-22 1990-11-22 Apparecchiatura frigorifera per banchi refrigerati a bassa temperatura in particolare per prodotti gelati e surgelati

Publications (1)

Publication Number Publication Date
EP0486758A1 true EP0486758A1 (fr) 1992-05-27

Family

ID=11253370

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91110117A Withdrawn EP0486758A1 (fr) 1990-11-22 1991-06-20 Appareil frigorifique pour des comptoirs frigorifiques à basse température, en particulier pour des produits congelés et surgelés

Country Status (2)

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EP (1) EP0486758A1 (fr)
IT (1) IT1243299B (fr)

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB494996A (en) * 1937-08-03 1938-11-04 Teves Kg Alfred Improvements in or relating to refrigerating machines
GB660697A (en) * 1949-03-17 1951-11-14 Internat Detrola Corp Improvements in or relating to refrigerating apparatus
US2685778A (en) * 1952-04-12 1954-08-10 Conrad Charles Fredrick Multiple stage refrigeration system
US3392541A (en) * 1967-02-06 1968-07-16 Larkin Coils Inc Plural compressor reverse cycle refrigeration or heat pump system
US3766745A (en) * 1970-03-16 1973-10-23 L Quick Refrigeration system with plural evaporator means
FR2380512A1 (fr) * 1977-02-09 1978-09-08 Sundstrand Deutschland Gmbh Procede pour recuperation de chaleur
US4205537A (en) * 1978-12-11 1980-06-03 General Electric Company Multiple hermetic-motor compressor in common shell
FR2455254A1 (fr) * 1979-04-27 1980-11-21 Bracht Armand Pompe a chaleur
US4438633A (en) * 1982-11-12 1984-03-27 Hiser Leland L Method and apparatus for using low grade thermal energy to improve efficiency of air conditioning and refrigeration systems
US4484449A (en) * 1983-02-15 1984-11-27 Ernest Muench Low temperature fail-safe cascade cooling apparatus
GB2180921A (en) * 1985-09-25 1987-04-08 Sanyo Electric Co Refrigeration system

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB494996A (en) * 1937-08-03 1938-11-04 Teves Kg Alfred Improvements in or relating to refrigerating machines
GB660697A (en) * 1949-03-17 1951-11-14 Internat Detrola Corp Improvements in or relating to refrigerating apparatus
US2685778A (en) * 1952-04-12 1954-08-10 Conrad Charles Fredrick Multiple stage refrigeration system
US3392541A (en) * 1967-02-06 1968-07-16 Larkin Coils Inc Plural compressor reverse cycle refrigeration or heat pump system
US3766745A (en) * 1970-03-16 1973-10-23 L Quick Refrigeration system with plural evaporator means
FR2380512A1 (fr) * 1977-02-09 1978-09-08 Sundstrand Deutschland Gmbh Procede pour recuperation de chaleur
US4205537A (en) * 1978-12-11 1980-06-03 General Electric Company Multiple hermetic-motor compressor in common shell
FR2455254A1 (fr) * 1979-04-27 1980-11-21 Bracht Armand Pompe a chaleur
US4438633A (en) * 1982-11-12 1984-03-27 Hiser Leland L Method and apparatus for using low grade thermal energy to improve efficiency of air conditioning and refrigeration systems
US4484449A (en) * 1983-02-15 1984-11-27 Ernest Muench Low temperature fail-safe cascade cooling apparatus
GB2180921A (en) * 1985-09-25 1987-04-08 Sanyo Electric Co Refrigeration system

Also Published As

Publication number Publication date
IT9041733A1 (it) 1992-05-23
IT9041733A0 (it) 1990-11-22
IT1243299B (it) 1994-05-26

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