WO2015052188A1

WO2015052188A1 - Ice making machine

Info

Publication number: WO2015052188A1
Application number: PCT/EP2014/071446
Authority: WO
Inventors: Guido Romagnoli
Original assignee: Frimont S.P.A.
Priority date: 2013-10-11
Filing date: 2014-10-07
Publication date: 2015-04-16
Also published as: ES2751422T3; KR102230581B1; DK3055636T3; CN105612399A; ITMI20131684A1; EP3055636A1; EP3055636B1; KR20160068782A

Abstract

An ice making machine comprising a coolant circuit comprising a coolant fluid based on a hydrocarbon, at least one evaporator, at least one expansion valve, at least one compressor, and at least one condenser (1) comprising a fin pack (3) and one or more rows of tubes (4) with a circular section fixed in through holes (5) of said tins (3), said tubes (4) having micro-grooves (9) on their inner surface such that the inner surface of said tubes (4) is greater than the outer surface, said micro-grooves (9) extending along spiral lines which wind around the longitudinal axis (L) of said tubes (4), said inner micro- grooves ( 9) of the tubes (4) being made without removal of material by means of crushing of the thickness of the tubes (4) performed along said lines of the inner surface of the tubes (4).

Description

ICE MAKING MACHINE

DESCRIPTION

The present invention relates to an ice making machine comprising a condenser for condensation of a coolant fluid based on a hydrocarbon.

The use of coolant fluids based on hydrocarbons such as propane in the cooling circuit of ice making machines is known, due to their high performance and their low environmental impact.

Said coolant fluids are often used in place of other types of coolant fluid, such as hydro fl u oroc arbon s , chlorofluorocarbons or hydrochlorofluorocarbons which have a decidedly worse environmental impact.

However, hydrocarbons also have a criticality linked with the fact of being extremely inflammable or explosive if exposed to sources of heat, flames or fumes, especially in enclosed and under-ventilated environments.

In order to limit the dangerousness of hydrocarbons, several specific regulations have been passed which provide for their use in limited quantities, below pre- established thresholds.

The sector of condensers for ice making machines has therefore recently been focusing on the search for construction solutions involving the use of hydrocarbons, but in the quantities allowed by the various safety regulations.

WO2013/ 1 06725 illustrates a condenser comprising two manifolds, flat connection tubes between the manifolds, and a pack of fins fixed between the flat sides of the tubes. In order to contain the inner volume of the condenser, the two manifolds have specific proportioning, and the flat tubes have a plurality of inner micro- channels alongside each other. One of the drawbacks of this type of condenser consists in the fact that the side zones facing between the micro-channels cannot be used for thermal exchange and do not contribute to improving efficiency of the condenser.

The technical task of the present invention is, therefore, to provide an ice making machine which eliminates the above-described technical drawbacks of the prior art. In said technical task, one object of the invention is to provide an ice making machine comprising a condenser for condensation of a coolant fluid based on a hydrocarbon which has an optimised efficiency, maintaining an extremely reduced inner volume.

Not least, an object of the invention is to provide an ice making machine comprising a simple and inexpensive condenser in its production process. The technical task, and also this and other objects, according to the present invention, are obtained by providing an ice making machine comprising a coolant circuit comprising a coolant fluid based on a hydrocarbon, at least one evaporator, at least one expansion valve, at least one compressor, and at least one condenser comprising a pack of fins and one or more rows of tubes with a circular section fixed in through holes of said fins, said tubes having micro-grooves on their inner surface such that the inner surface of said tubes is greater than their outer surface, characterised in that said micro-grooves extend along spiral lines which wind around the longitudinal axis of said tubes, said inner micro-grooves of the tubes being made without removal of material by means of crushing of the thickness of the tubes performed along said lines of the inner surface of the tubes. The method for making the condenser provides for a step of coupling the tubes in the holes of the fins of the fin pack, and is characterised in that the inner micro- grooves of the tubes are made without removal of material.

Preferably, the micro-grooves are made by crushing of the thickness of the tubes performed along lines of the inner surface of the tubes.

The advantages deriving from the ice making machine according to the invention are numerous.

Whereas in traditional condenser tubes of the same type having a smooth inner wall, there is a layer of laminar flow adjacent to the inner wall of the tubes which creates a barrier to heat transfer, in the tubes of a condenser according to the invention, the micro-grooves prevent the formation of the layer of laminar flow and therefore guarantee the creation of a turbulent flow on the entire inner section of the tubes, thus considerably improving the efficiency of thermal exchange.

For this reason as well, tubes of reduced diameter may be used, which allow many more options for the air circuits which are created around the tubes.

In an ice making machine according to the invention, a condenser having internally grooved tubes with a reduced diameter allows, with the same performance a reduction of the inner volume of the condenser, with the same exchange surface an increase in performance, and, with the same volume an increase in performance. Other characteristics of the present invention are also defined in the claims which follow.

Further characteristics and advantages of the invention will more fully emerge from the description of a preferred but not exclusive embodiment of the ice making machine according to the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Fig. la shows a perspective view of the condenser according to a preferred embodiment of the invention;

Fig. lb shows a raised side view of the condenser of Fig. la;

Fig. 1 c shows a rear view of the condenser of Fig. l a;

Fig. 2 shows in detail a portion of the fin pack of the condenser of Fig. l a with the tubes arranged across it, without the curved ends of coupling between the tubes, in order to appreciate the design of the inner surface of said tubes;

Fig. 2a shows an enlarged detail of the coupling of a tube in a hole of the fins of the fin pack of Fig. 2;

Fig. 3 shows a transversal section of a tube of the condenser of Fig. 1 a;

Fig. 4 shows a longitudinal section of a tube of the condenser of Fig. l a; and Fig. 5 shows the tool in the sequence of steps with which the micro-grooves of the tube are made.

With reference to the above mentioned figures, a condenser of an ice making machine is shown, denoted in its entirety by reference number 1.

In particular, reference will be made to a condenser for the condensation of a coolant fluid based on a hydrocarbon, preferably propane.

The ice making machine (not shown) has a coolant circuit of the known type, which comprises, in addition to said condenser 1 , also an evaporator on the surface o which the ice forms, a lamination valve and a compressor.

The condenser 1 comprises a box-shaped support frame 2, in particular parallelepiped, in which is housed a fin pack 3 and a plurality of tubes 4 fixed in through holes 5 of the fins 3.

The tubes 4 preferably have, as illustrated, a circular section and a straight longitudinal axis L.

The tubes 4 are arranged parallel to each other and with the longitudinal axis L horizontal and perpendicular with two flat side faces 2a, 2a vertical and opposite the frame 2.

The flat side faces 2a, 2a of the frame 2 in turn have support through holes of the tubes 4 from which the ends of said tubes 4 exit.

The tubes 4 are arranged in groups, in each of which the tubes 4 are connected in series, at the outer side o the flat side faces 2a, 2a of the frame 2, by means of special 180° connectors 10, 10', so as to form coils which may be supplied in parallel with the coolant fluid.

The tubes 4 are also arranged in one or more rows of tubes 4, that are on one or more flanked parallel vertical planes.

Other connectors 10 connect the tubes 4 belonging to the same row of tubes 4, other connectors 10' connect the tubes 4 belonging to adjacent rows of tubes 4. Obviously, the shape of the coils may be customised as desired by means of special arrangements of the connectors 1 0, 10' for connection between the tubes 4 of the same row or different rows.

The ends of the coils for entry of the coolant fluid are connected to each other by a special inlet manifold 7, and, similarly, the ends of the coils for exit of the coolant fluid are connected to each other by a special outlet manifold 8. The inlet manifold 7 and the outlet manifold 8 are in this case positioned on the outer side of a same fiat side face 2a of the frame 2, but could be positioned on the outer side of different faces of the frame 2.

The fins 3 have a same substantially quadrangular flat shape and are aligned parallel to each other along an alignment axis oriented in the direction of the longitudinal axis L of the tubes 4.

The fins 3 also have longitudinal slits 6 which penetrate for the entire thickness of the fins 3, creating passages for air also in the direction of the alignment axis of the fins 3.

In other embodiments, the slits of the fins 3 may not be provided.

The fins 3 and the tubes 4 may be made of an identical or also different thermally conductive material: for example, it is possible to provide fins 3 in aluminium and tubes 4 in copper.

One of the salient aspects of the condenser consists in the fact that the tubes 4 have micro-grooves 9 on their inner surface.

Preferably, the micro-grooves 9 are configured and arranged so that the inner surface of the tubes 4 is greater than their outer surface.

The micro-grooves 9 extend preferably along spiral lines which wind around the axis L of the tubes 4 for the entire longitudinal extension of the tubes 4.

The tubes 4 have a minimum inner thickness "d" between 0.1 mm and 0.3 mm at the bottom 9a of the micro-grooves 9, a maximum inner thickness "D" between 0.15 mm and 0.6 mm at the top 9b of the micro-grooves 9, and an outer diameter φ comprised between 4 mm and 12 mm. The micro-grooves 9 also extend parallel to each other with a spacing step not exceeding 1 mm.

The increase in the exchange surface determined by the micro-grooves 9 allows tubes 4 with a limited diameter to be obtained and a total inner volume of the tubes such as to house no more, than 150 grams of coolant fluid, in accordance with the strictest safety requirements, maintaining optimal performance for the condenser 1. Advantageously, the micro-grooves 9 of the tubes 4 are made without removal of material, in order not to weaken the structure and penalise functioning of the tubes 4.

The mi cro-grooves 9 are therefore made by crushing of the thickness of the tubes 4 performed along specific lines of the inner surface of the tubes 4, for example as described above along helicoidal lines which wind around the longitudinal axis L of the tubes 4.

The micro-grooves 9 are advantageously made, after coupling the tubes 4 in the holes 5 of the fins 3 of the fin pack, by means of a radial force applied from inside the tubes 4 and at least sufficient to create the micro-grooves 9 together with a slight radial expansion of the tubes 4 which consolidates coupling of the tubes 4 into the holes 5 of the fins 3 of the fin pack.

In practice, for making of the micro-grooves 9, a tool 1 1 is used having a stem 12 which ends with a tapered work head 13, and a coaxial gripper 1 5 external to the stem 12 and provided with radially retractable grip sectors 15a.

After fitting the fins 3 onto the tubes 4, the tubes 4 are blocked in position by means of a blocking device 14 which tightens the connectors 10, 10'. Initially, the work head 13 of the tool 1 1 is pointed against an end of a tube 4 and the gripper 15 translates axiaily until it surmounts the end of the tube 4.

Subsequently, the gripper 1 5 tightens on the tube 4 causing its sectors 15a to retract radially.

With the gripper 15 tightened on the tube 4, the stem 12 translates axiaily in the direction of introduction into the tube 4 and the stem 12 rotates in a synchronised way on its own axis.

The work head 13 has a perimeter corner of moulding 13a which engages against the inner surface of the tube 4, exerting a crushing force of the thickness of the tube 4.

The roto-translational movement of the tool continues along the entire longitudinal extension of the tube 4 for completion of the helicoidal micro-grooves 9.

The crushing force of the thickness of the tube 4 from inside is at least sufficient also to expand radially the section of the tubes 4.

This slight radial expansion of the tubes 4 produces, at the holes 5, a plastic deformation 5' of the wall of the holes 5, with which the holes 5 tighten more firmly on the tube 4.

The ice making machine as conceived herein is susceptible to many modifications and variations, all falling within the scope of the inventive concept; furthermore, all the details are replaceable by technically equivalent elements.

The materials used, as well as the dimensions, may in practice be of any type according to requirements and the state of the art.

Claims

1. An ice making machine comprising a coolant circuit comprising a coolant fluid based on a hydrocarbon, at least one evaporator, at least one expansion valve, at least one compressor, and at least one condenser (1) comprising a fi pack (3) and one or more rows of tubes (4) with a circular section fixed in through holes (5) of said fins (3), said tubes (4) having micro-grooves (9) on their inner surface such that the inner surface of said tubes (4) is greater than the outer surface, characterised in that said micro-grooves (9) extend along spiral lines which wind around the longitudinal axis (L) of said tubes (4), said inner micro-grooves (9) of the tubes (4) being made without removal of material by means of crushing of the thickness of the tubes (4) performed along said lines of the inner surface of the tubes (4).

2. The ice making machine according to the previous claim, characterised in that said tubes (4) have a minimum inner thickness (d) comprised between 0.1 and 0.3 mm at the bottom of said micro-grooves (9), a maximum inner thickness (D) comprised between 0.1 5 and 0.6 mm at the top of said micro-grooves (9), and an outer diameter (φ) comprised between 4 and 12 mm.

3. The ice making machine according to any one of the previous claims, characterised in that said micro-grooves (9) have a spacing step not exceeding 1 mm.

4. The ice making machine according to any one of the previous claims, characterised in that the total inner volume of said tubes (4) is such as to house a quantity of coolant fluid not exceeding 150 grams.

5. The ice making machine according to any one of the previous claims, characterised in that said hydrocarbon is propane.

6. The ice making machine according to any one of the previous claims, characterised in that said tubes (4) are made o copper and said fins (3) are made of aluminium.