WO2011092587A2

WO2011092587A2 - System for optimizing the distribution of the coolant fluid in a heat exchange device

Info

Publication number: WO2011092587A2
Application number: PCT/IB2011/000141
Authority: WO
Inventors: Angelo Muzzolon; Pierangelo Piubello
Original assignee: Alfa Laval Corporate Ab
Priority date: 2010-01-28
Filing date: 2011-01-27
Publication date: 2011-08-04
Also published as: CN201945244U; IT1397911B1; WO2011092587A3; ITMI20100117A1; WO2011092587A8

Abstract

A system is described for optimizing the distribution of the coolant fluid in a heat exchange device (10) of the type comprising a plurality of elements (12) arranged alongside one another and in hydraulic connection with one another. The elements (12) are internally provided with a first series of channels for the circulation of a first fluid, or coolant fluid, consisting of a biphase liquid/vapour mixture, and with a second series of channels for the circulation of a second fluid, or fluid to be cooled, capable of exchanging heat energy, through the walls of the elements (12), with such coolant fluid. The first series of channels is provided with a first inlet duct (14) for the coolant fluid and with a first outlet duct (16) for such a coolant fluid, whereas the second series of channels is provided with a second inlet duct (18) for the fluid to be cooled and with a second outlet duct (20) for such a fluid to be cooled. Along the first inlet duct (14) for the coolant fluid, upstream of the elements (12), there is at least one flow pattern modifying device (22) of the biphase liquid/vapour mixture, provided with at least one element (24; 32) capable of at least partially occluding such a first inlet duct (14) for the coolant fluid, so as to modify, according to a predetermined shape, the passage section of such first inlet duct (14) and optimize the distribution of the coolant fluid entering the heat exchange device (10), preventing the oversupply with coolant fluid of the first channels of the heat exchange device (10) arranged at such first inlet duct (14).

Description

FOR OPTIMIZING THE DISTRIBUTION OF THE COOLANT IN A HEAT EXCHANGE DEVICE

The present invention in general refers to a heat exchange device and, more in particular, to a system for optimizing the distribution of the coolant fluid in such a heat exchange device .

As it is known, in a heat exchange device there is an exchange of thermal energy between two fluids at different temperatures. In general, heat exchange devices are open systems that operate without work exchange, or in other words, they have constant flow of fluid and a constant temperature distribution.

Amongst the various types of heat exchange devices, there are plate heat exchangers, in which the two fluids normally lick the opposite sides of a metal plate, which can be corrugated or flat, in alternate chambers and isolated from one another. In other words, in a heat exchanger of the type with plates, the two fluids at different temperatures (one of which is usually called coolant fluid) exchange their heat content through one or more surfaces, generally made with reliefs and arranged next to each other, in which such fluids alternate with concurrent or countercurrent flow and the circulation of which is given by the gaskets or by the welding or brazing between the surfaces themselves.

Due to their particular configuration, plate heat exchangers have heat exchange coefficients that are very high and can be used in heat exchange applications between different types of fluids (superheated water, hydraulic oils, steam, HFC coolant, etc.) and in general in all those cases in which low heat exchange coefficients, due to the characteristics of the fluids or to low speeds thereof, require special provisions in order to increase the heat exchange coefficients themselves .

One of the most common uses of plate exchangers is that of acting as evaporators for evaporating coolants (for example, HFC) in refrigeration systems. Such refrigeration systems normally include a steam compressor, a condenser, an expansion valve and an evaporator. The coolant fluid entering the evaporator is normally a liquid/vapour biphase mixture, as a result of passing through the expansion valve.

A correct distribution of the liquid/vapour biphase mixture to the channels of the plates is one of the main factors that contribute towards keeping the performance of a plate heat exchanger high. In other words, an even distribution of the coolant fluid through the channels of the plates makes it possible to obtain the best performances, in terms of maximum temperature of evaporation at a given cooling capability.

Current distribution systems of coolant fluid inside a plate heat exchanger, in particular of the so called "brazed plate" type, are based upon a localised pressure drop at the inlet of each duct for supplying the coolant fluid itself. Such a drop in pressure is obtained through suitable nozzles and/or particular devices (such as for example premixers, etc.) installed on the inlet duct of the coolant fluid.

Systems known to this day for the distribution of coolant fluid inside a heat exchanger, like for example those illustrated in American patents N. US 4 928 494, US 5 417 083, US 6 915 648 and US 6 926 250, are however rather complex and costly to make .

Moreover, the first channels of the heat exchange device, i.e. the closest channels to the inlet duct of the heat exchange device itself, can be subjected to an oversupply with evaporating liquid (the coolant liquid flowing in such channels pass from the liquid state to the gaseous state) . This results in the presence of drops of liquid in the steam exiting from the heat exchange device, with negative consequences on the operation stability of the heat exchange device itself.

The general purpose of the present invention is therefore that of making a system for optimizing the distribution of the coolant fluid in a heat exchange device capable of solving the aforementioned drawbacks of the prior art in an extremely simple, cost-effective and particularly functional manner.

In particular, one purpose of the present invention is that of making a system for optimizing the distribution of the coolant fluid in a heat exchange device capable of efficiently modifying the flow characteristics of the coolant fluid entering the channels present inside the elements of the heat exchange device itself .

Another purpose of the invention is that of making a system for optimizing the distribution of the coolant fluid in a heat exchange device that can be obtained with mechanical and electric components that are simple and particularly cost-effective.

A further purpose of the present invention is that of making a system for optimizing the distribution of the coolant fluid in a heat exchange device allowing to obtain a steam without drops of liquid exiting from such heat exchange device, thus obtaining a steadier overheating resulting in a better operation stability.

These purposes according to the present invention are achieved by making a heat exchange device and a relative system for optimizing the distribution of the coolant fluid as outlined in claim 1.

Further characteristics of the invention are highlighted in the dependent claims, which are an integral part of the present description.

The characteristics and the advantages of the system for optimizing the distribution of the coolant fluid according to the present invention in a heat exchange device of the plate type (or similar) shall become clearer from the following description, given as an example and not for limiting purposes, with reference to the attached schematic drawings in which: figure 1 is a perspective schematic view of a heat exchange device of the plate type to which a system, for optimizing the distribution of the coolant fluid according to the present invention, can be applied;

figure 2 is a schematic view that illustrates the flow of coolant fluid inside a heat exchange device of the plate type like that of figure 1;

figure 3 is a schematic view that illustrates a first embodiment of a system for optimizing the distribution of the coolant fluid according to the present invention;

figure 4 is a side view, partially in section, of the system for optimizing the distribution of the coolant fluid of figure 3;

figure 5 is a front view, partially in section, of the system for optimizing the distribution of the coolant fluid of figure 3;

figure 6 is a schematic view that illustrates a second embodiment of a system for optimizing the distribution of the coolant fluid according to the present invention,- figure 7 is a front view, partially in section, of the system for optimizing the distribution of the coolant fluid of figure 6;

figure 8 shows a first configuration of a component of the system for optimizing the distribution of the coolant fluid of figure 6; and

figure 9 shows a second configuration of a component of the system for optimizing the distribution of the coolant fluid of figure 6.

With reference in particular to figure 1, a heat exchange device of the plate type is shown, wholly indicated with reference numeral 10. The heat exchange device 10, or heat exchanger, comprises a plurality of elements or plates 12 arranged alongside one another and in hydraulic connection with one another.

The plates 12, made from metal and preferably of the corrugated type, are internally provided with a first series of channels for the circulation of a first fluid, or coolant fluid, and with a second series of channels for the circulation of a second fluid, or fluid to be cooled, capable of exchanging heat energy, through the walls of the plates 12 themselves, with such a coolant fluid. The first fluid, or coolant fluid, entering the heat exchange device 10, is a liquid/vapour biphase mixture. The plates 12 are in contact with one another at points and can be joined through the interposition of sealing gaskets, made from rubber or from another elastomeric material, or through welding (so called "brazed plates").

The two series of channels for the two fluids at different temperature are independent from one another and such fluids can have both a countercurrent flow or a concurrent flow. More precisely, the first series of channels is provided with a first inlet duct 14 for the coolant fluid and with a first outlet duct 16 for such a coolant fluid. Similarly, the second series of channels is provided with a second inlet duct 18 for the fluid to be cooled and with a second outlet duct 20 for such a fluid to be cooled.

Along the inlet duct 14 for the coolant fluid, upstream of the plates 12, there can be one or more expansion valves (not shown) or other devices capable of reducing the pressure of the coolant fluid in inlet into the heat exchanger 10. According to the invention, again along the inlet duct 14 for the coolant fluid, upstream of the plates 12 and downstream of the aforementioned devices capable of reducing the pressure of the coolant fluid in inlet into the heat exchanger 10, there is at least one flow characteristic or "flow pattern" modifying device 22 of the liquid/vapour biphase mixture, provided with at least one element capable of at least partially occluding such an inlet duct 14 for the coolant fluid.

In this way, the modification, according to a predetermined shape, of the passage section of the inlet duct 14 is obtained and the distribution of the coolant fluid supplying the various channels of the heat exchange device 10 is optimized. In particular, the oversupply of the first channels with evaporating fluid (liquid) is prevented, since the coolant fluid flowing in the inlet duct is subjected to the "shadow cone" effect caused by the device 22 depending on its shape and position, being mostly deviated in the channels successive to the first ones.

The flow pattern modifying device 22 can operate both in a static manner, that is to say with a fixed element that at least partially occludes the inlet duct 14 for the coolant fluid, and in a dynamic manner, therefore with one or more mobile elements for occluding such an inlet duct 14.

Based upon a first embodiment, shown in figure 3, the flow pattern modifying device 22 comprises a gate valve 24 that faces inside the inlet duct 14 for the coolant fluid. The gate valve 24 is mobile with linear motion in the radial direction with respect to the direction of extension of the inlet duct 14 for the coolant fluid. The linear movement of the gate valve 24 can be controlled by a manually actuated device or through a motor 26, preferably of the electric type, through the interposition of a plunger 28. As shown in figure 5, the operative end 30 of the gate valve 24, that is to say, the end that is capable of intercepting the flow of coolant fluid passing through the relative inlet duct 14, is preferably wedge shaped, even though it can be wedge shaped with a point, or rounded, or with a circular segment or with another proper shape.

Based upon a second embodiment, shown in figure 6, the flow pattern modifying device 22, on the other hand, comprises a perforated disc 32 placed inside the inlet duct 14 for the coolant fluid and arranged perpendicular with respect to the direction of extension of the inlet duct 14 itself. The perforated disc 32 has an inner hole 34, suitably shaped so as to allow the regulation of the flow of coolant fluid passing through the relative inlet duct 14, and is provided with a suitably shaped inner wall 46, capable of partially occluding such a hole 34. As shown in figure 8, the inner wall 46 can be provided with an end having a rounded shape. Figure 9, on the other hand, shows an inner wall 46 having a flat shaped end.

The perforated disc 32 can be arranged in a fixed manner inside the inlet duct 14 for the coolant fluid, with a suitable orientation of the relative inner wall 46, for example through welding or directly formed on the connection between the supply tube of the coolant fluid in the device 10 and such an inlet duct 14 for the coolant fluid itself. Alternatively, the perforated disc 32 can be mobile with rotary motion inside the inlet duct 14 for the coolant fluid. Basically, in this case the end of the inner wall 46 is set in rotation to intercept and modify the flow pattern of the coolant fluid flowing through the relative inlet duct 14.

When made in a mobile manner, the perforated disc 32 is circumferentially provided with a toothing 36 capable of engaging with a corresponding toothing 38 provided on a gear 40, in turn set in rotation either by a motor 42, preferably of the electric type, through the interposition of a rotary shaft 44, or by a manually actuated device.

A flow pattern modifying device 22 of a heat exchanger 10 like that according to the invention is thus cost-effective and simple to make. Experimental tests carried out by the applicant have demonstrated that such a flow pattern modifying device 22, when present along the inlet duct 14 of the coolant fluid, is capable of improving the overall performances of the heat exchange device 10, both when it is of the static type and when it is suitably actuated through rotation or translation according to the specific embodiment.

When made in a mobile manner, i.e. when suitably actuated by rotation (perforated disc 32) or translation (gate valve 24) , the flow pattern modifying device 22 can be actuated also by a specific electronic control device 48, operatively connected to the respective electric motor 26 or 42, for a more effective operation of the flow pattern modifying device 22 itself.

It has thus been seen that the system for optimizing the distribution of the coolant fluid in a heat exchange device according to the present invention achieves the purposes previously highlighted, allowing to obtain a steam without liquid drops exiting from such heat exchange device and thus obtaining a steadier overheating, resulting in a better operation stability.

The system for optimizing the distribution of the coolant fluid in a heat exchange device according to the present invention thus conceived can in any case undergo numerous modifications and variants, all covered by the same inventive concept; moreover, all the details can be replaced by technically equivalent elements. In practice the materials used, as well as the shapes and sizes can be any according to the technical requirements .

The scope of protection of the invention is thus defined by the attached claims.

Claims

1. System for optimizing the distribution of the coolant fluid in a heat exchange device (10) of the type comprising a plurality of elements (12) arranged alongside one another and in hydraulic connection with one another, said elements (12) being internally provided with a first series of channels for the circulation of a first fluid, or coolant fluid, consisting of a biphase liquid/vapour mixture, and with a second series of channels for the circulation of a second fluid, or fluid to be cooled, capable of exchanging heat energy, through the walls of the elements (12) , with said coolant fluid, said first series of channels being provided with a first inlet duct (14) for the coolant fluid and with a first outlet duct (16) for said coolant fluid, and said second series of channels being provided with a second inlet duct (18) for the fluid to be cooled and with a second outlet duct (20) for said fluid to be cooled, the system being characterised in that it comprises at least one flow pattern modifying device (22) of the biphase liquid/vapour mixture, arranged along said first inlet duct (14) for the coolant fluid, upstream of the elements (12) , said flow pattern modifying device (22) being provided with at least one element (24; 32) capable of at least partially blocking off said first inlet duct (14) for the coolant fluid so as to modify, according to a predetermined shape, the passage section of said first inlet duct (14) and optimize the distribution of the coolant fluid entering the heat exchange device (10) , preventing the oversupply with coolant fluid of the first channels of the heat exchange device (10) arranged at said first inlet duct (14) .

2. System for optimizing the distribution of the coolant fluid according to claim 1, characterised in that said flow pattern modifying device (22) comprises a gate valve (24) that faces inside said first inlet duct (14) for the coolant fluid.

3. System for optimizing the distribution of the coolant fluid according to claim 2, characterised in that said gate valve (24) is mobile with linear motion in the radial direction with respect to the direction of extension of said inlet duct (14) for the coolant fluid.

4. System for optimizing the distribution of the coolant fluid according to claim 3, characterised in that the linear movement of said gate valve (24) is controlled by a first electric motor (26) through the interposition of a plunger (28) .

5. System for optimizing the distribution of the coolant fluid according to claim 4, characterised in that said gate valve (24) is actuated by a specific electronic control device (48) , operatively connected to said first electric motor (26) , for a more effective operation of said flow pattern modifying device (22) .

6. System for optimizing the distribution of the coolant fluid according to claim 3, characterised in that the linear movement of said gate valve (24) is controlled by a manually actuated device.

7. System for optimizing the distribution of the coolant fluid according to any one of claims 2 to 6, characterised in that the operative end (30) of said gate valve (24) , in other words the end capable of intercepting the flow of coolant fluid transiting through said inlet duct (14) , is wedge shaped.

8. System for optimizing the distribution of the coolant fluid according to any one of claims 2 to 6, characterised in that the operative end (30) of said gate valve (24) , in other words the end capable of intercepting the flow of coolant fluid transiting through said inlet duct (14) , is wedge shaped with a point, or it is rounded shaped, or it is shaped as a circular segment or has another appropriate shape.

9. System for optimizing the distribution of the coolant fluid according to claim 1, characterised in that said flow pattern modifying device (22) comprises a disc (32) placed inside said inlet duct (14) for the coolant fluid and provided with a suitably shaped inner hole (34) to intercept and modify the pattern flow of the coolant fluid transiting through said inlet duct (14) .

10. System for optimizing the distribution of the coolant fluid according to claim 9, characterised in that said disc (32) is arranged perpendicularly to the direction of extension of said inlet duct (14) for the coolant fluid and is fixed inside said inlet duct (14) for the coolant fluid.

11. System for optimizing the distribution of the coolant fluid according to claim 9, characterised in that said disc (32) is arranged perpendicularly to the direction of extension of said inlet duct (14) for the coolant fluid and is mobile with rotary motion inside said inlet duct (14) for the coolant fluid.

12. System for optimizing the distribution of the coolant fluid according to claim 11, characterised in that said disc (32) is circumferentially provided with a toothing (36) capable of engaging with a corresponding toothing (38) foreseen on a gear (40) , in turn set in rotation by a second electric motor (42) , through the interposition of a rotary shaft (44) , or else by a manually actuated device .

13. System for optimizing the distribution of the coolant fluid according to claim 12, characterised in that said disc (32) is actuated by a specific electronic control device (48) , operatively connected to said second electric motor (42) , for a more effective operation of said flow pattern modifying device (22) .

14. System for optimizing the distribution of the coolant fluid according to any one of claims 9 to 13, characterised in that said disc (32) is provided with a suitably shaped inner wall (46) , capable of partially blocking off said hole (34) .

15. System for optimizing the distribution of the coolant fluid according to claim 14, characterised in that said inner wall (46) is provided with an end having a rounded shape.

16. System for optimizing the distribution of the coolant fluid according to claim 14, characterised in that said inner wall (46) is provided with an end having a flat shape .