WO2018078341A1

WO2018078341A1 - Expansion vessel for a heating or cooling system

Info

Publication number: WO2018078341A1
Application number: PCT/GB2017/053187
Authority: WO
Inventors: Richard Cowley; Darren Wilkinson
Original assignee: Vexo International (Uk) Limited
Priority date: 2016-10-26
Filing date: 2017-10-23
Publication date: 2018-05-03
Also published as: US20190277512A1; GB2555425B; GB201618127D0; GB2555425A; EP3519738A1

Abstract

An expansion vessel (101, 201) for use in a fluid circuit of a heating or cooling system (102) defines a fluid inlet port (103) and further defines a fluid outlet port (104), separate from the fluid inlet port (103). The separate fluid inlet and outlet ports (103, 104) allow fluid to flow through the expansion vessel (101, 102) along a fluid flow path from the fluid inlet port (103) to the fluid outlet port (104) to avoid stagnation of fluid within the expansion vessel (101, 201). A method of installing the expansion vessel (101, 201) in a heating or cooling system (102) having a fluid circuit. A heating or a cooling system (102) comprising a fluid circuit provided with the expansion vessel (101, 201).

Description

EXPANSION VESSEL FOR A HEATING OR COOLING SYSTEM

Field of the Invention

The present invention relates to an expansion vessel for use in a fluid circuit of a heating or a cooling system.

Background of the Invention

Heating and cooling systems often comprise a fluid circuit through which a fluid is circulated under pressure, for example, a closed circuit central heating system where water flows in a loop from the boiler, through a series of radiators and then back again to the boiler.

Such systems are often protected from expansion of the fluid by a small vessel known as an expansion vessel. This is normally a small container divided in half by a diaphragm, the top half usually being filled with pressurized air (the dry half), and the lower half being connected to the heating or cooling system and therefore able to be filled with fluid, such as water (the wet half). As the temperature and/or pressure in the heating system rises, fluid enters the vessel through the inlet/outlet port and the diaphragm is pushed up, compressing the air on the other side (the dry half). Once the system pressure falls again, fluid can leave the vessel through the same port and the diaphragm is pushed back towards the wet half, by the compressed air in the dry half.

A particular problem of this arrangement is that, because fluid enters and leaves the vessel through the same port, a "dead leg" is created. This is a region within the system where fluid does not move for a period of time. Fluid in such a "dead leg" may become stagnant and therefore more susceptible to bacterial growth and the effects of corrosion.

Bacteria are generally present within mains water supplies. These are normally harmless to people at the levels found in fresh water, but where mains water is used to initially fill a heating or cooling system, the already-present bacteria can multiply in areas of the system where water stagnates, forming a biofilm (a mixture of live and dead bacteria which can create a layer on pipe surfaces). This biofilm can cause a number of problems, including corrosion, reduction of heat transfer, reduced efficacy of corrosion inhibitors, the reduced efficacy of biocides and even reduced water flow.

Heating systems are particularly vulnerable to such bacterial growth as any "dead legs" associated with expansion vessels often contain hot water which is cooling, creating perfect bacterial temperatures. Further, the longer the "dead leg", the greater the potential for bacterial growth.

To resolve this, it is desirable to remove any such "dead legs" and prevent, where possible, the stagnation of fluid within the expansion vessel.

It is hence an object of the present invention to provide an alternative to existing expansion vessel arrangements that obviates the above problems. Summary of the Invention

According to a first aspect of the present invention, there is provided an expansion vessel for use in a fluid circuit of a heating or cooling system, said expansion vessel comprising: a first internal volume, for receiving fluid from the fluid circuit, and a second internal volume, for containing air, said first and second internal volumes being separated by a diaphragm, and said expansion vessel defining a fluid inlet port for allowing fluid within said fluid circuit to flow therethrough into the first internal volume of the expansion vessel, wherein said expansion vessel further defines a fluid outlet port, separate from said fluid inlet port, for allowing fluid within the first internal volume of the expansion vessel to flow therethrough into the fluid circuit; whereby the fluid inlet port and the fluid outlet port allow a continuous flow of fluid through said first internal volume along a flow path from the fluid inlet port to the fluid outlet port.

The expansion vessel thus has a wet half and a dry half, and stagnation of fluid within the wet half of the expansion vessel is hence reduced or even eliminated, reducing bacterial growth therein.

The wet half of the expansion vessel may advantageously be provided with an air outlet port. The air outlet port may be located adjacent the diaphragm. The air outlet port may be provided with a manually-operable air vent or an automatic air vent. The air outlet port beneficially allows trapped air to be released from the wet half of the expansion vessel. The fluid outlet port may be located in a base wall of the expansion vessel.

The fluid inlet port may also be located in the base wall of the expansion vessel. The expansion vessel may then be conveniently wall-mountable. The fluid inlet port may alternatively be located in a side wall of the expansion vessel. The expansion vessel may then be conveniently mountable on a floor surface.

A fluid flow path extending from the fluid inlet port within the expansion vessel may advantageously be defined by a flow path director. The flow path director may comprise a self-supporting structure. The flow path director may comprise a tubular element, which may be provided by or comprise pipework. The flow path director may comprise a tubular element that is formed as a tubular coil. The tubular element may have a first end adjacent the fluid inlet port, and a second, open end. The second, open end may be positioned at a substantially higher level within the expansion vessel than the fluid inlet port. The tubular element may extend adjacent an inner wall of the expansion vessel. The tubular element may define a plurality of orifices along the length thereof.

According to a second aspect of the present invention, there is provided a method of installing an expansion vessel according to the first aspect in the fluid circuit of a heating or cooling system.

According to a third aspect of the present invention, there is provided a heating system comprising a fluid circuit provided with an expansion vessel according to the first aspect. According to a fourth aspect of the present invention, there is provided a cooling system comprising a fluid circuit provided with an expansion vessel according to the first aspect. Brief Description of the Drawings

The present invention will now be more particularly described, with reference to the accompanying drawings, in which:

Figure I is a schematic diagram of a heating or cooling system containing a known expansion vessel, in which fluid enters the expansion vessel through an inlet/outlet as system pressure increases then exits the expansion vessel by the same inlet/outlet as system pressure increases;

Figure 2 is a schematic diagram of a heating or cooling system containing an expansion vessel comprising separate fluid inlet and outlet ports, the expansion vessel being wall-mounted;

Figure 3 is a side view of an expansion vessel with separate fluid inlet, fluid outlet and air outlet ports;

Figure 4 is a cross-section along line B-B of the expansion vessel shown in Figure 3;

Figure 5 is a schematic diagram of a heating or cooling system containing an expansion vessel comprising separate fluid inlet and outlet ports, the expansion vessel being floor-standing;

Figure 6 is a side view of an expansion vessel for use in a heating or cooling system, the expansion vessel defining a wet half and a dry half and comprising a fluid inlet port provided in a side wall of the wet half, a separate fluid outlet port provided in a lower region of the wet half and a separate fluid outlet port provided in an upper region of the wet half; and

Figure 7 is a cross-section along line AA of the expansion vessel shown in Figure 6.

Description

Example embodiments are described below in sufficient detail to enable those of ordinary skill in the art to embody and implement the apparatus, systems and processes herein described. It is to be understood that the invention should not be construed as limited to the examples or specific details thereof set forth herein but can be provided in many alternate forms falling within the scope of the invention is defined by the appended claims. A schematic diagram of a heating or cooling system containing a prior art expansion vessel, in which fluid enters the expansion vessel through an inlet/outlet as pressure increases then exits the expansion vessel by the same inlet/outlet as pressure increases, is shown in Figure I .

Prior art expansion vessel A I is shown arranged for use within a heating or cooling system A2. The prior art expansion vessel A I comprises a combined inlet/outlet port A3 and a diaphragm A4 between a dry half and a wet half thereof. Generally, a system such as heating or cooling system A2 will also comprise a system boiler or chiller A5, a system pump A6, a system heat exchanger A7, a fluid flow pipe A8 and a fluid return pipe A9.

During operation of the heating or cooling system A2, under the condition in which pressure within the system is increasing, fluid enters the wet half of the expansion vessel A I through the inlet/outlet port A3, causing the diaphragm A4 to pushed up and air within the dry half of the prior art expansion vessel A I to be compressed. In addition, fluid within the wet half of the prior art expansion vessel A I is prevent from leaving by fluid flowing into the wet half of the prior art expansion vessel A I through the inlet/outlet port A3.

Fluid that has entered the wet half of the prior art expansion vessel A I may remain there for some time, until the condition is reached in which pressure within the heating or cooling system A2 has fallen sufficiently for the fluid to drain out of the wet half of the prior art expansion vessel A I through the inlet/outlet port A3. During the intervening period, fluid within the wet half of the vessel A I and the inlet/outlet port A3 can stagnant and increased bacterial growth within the system fluid can result.

An expansion vessel 101 is shown in Figure 2, within a heating or cooling system 102 with fluid circuit. In this embodiment, the expansion vessel 101 is wall-mounted.

The expansion vessel 101 comprises a first internal volume for receiving fluid from the fluid circuit (wet half) and a second internal volume for containing air (dry half). The expansion vessel 101 defines a fluid inlet port 1 03 for receiving circulating fluid into the expansion vessel 101 from the fluid circuit, and a separate fluid outlet port 104 for returning circulating fluid from the expansion vessel 101 to the fluid circuit.

The expansion vessel 101 further comprises a diaphragm 105 that divides the expansion vessel into a wet half, for receiving system fluid, and a dry half, typically filled with pressurized air. The wet half is provided by the first internal volume and the dry half is provided by the second internal volume. The first internal volume (wet half) is open, and is configured to allow fluid from the fluid circuit to flow therethrough, and the second internal volume (dry half) is sealed, and contains air. In addition to the expansion vessel, the illustrated heating or cooling system 102 comprises a system boiler or chiller 106, a pump 107, a system heat exchanger 108, a fluid flow pipe 109 and a fluid return pipe I 10. During system operation, system fluid can circulate the fluid circuit, and through the wet half of the expansion vessel 101. The separate fluid inlet and outlet ports 103, 104 of the expansion vessel 101 are relatively located so that fluid from the fluid circuit may flow continuously through the wet half of the expansion vessel 101 , from the fluid inlet port 103 to the fluid outlet port 104, this flow serving to reduce or avoid undesired stagnation of system fluid within the wet half of expansion vessel 101.

According to the present embodiment, the expansion vessel 101 further defines an air outlet port 1 16. In this illustrated example, the air outlet port I 1 6 is located in a region of the wet half of the expansion vessel 101 adjacent the diaphragm 105. The air outlet port I 16 allows air to exit from the wet half of the expansion vessel 101 , this serving to reduce or prevent undesired trapped air. As shown, air outlet port I 16 is separate from each of the fluid inlet port 103 and the fluid outlet port 104. In an example, the air outlet port I 16 is provided with a manually-operable air vent. In an alternative example, the air outlet port I 16 is provided with an automatic air vent. Figure 3 shows a side view of the expansion vessel 101 of Figure 2, and Figure 4 shows a cross-section of the expansion vessel 101 along line B-B shown in Figure 3. As can be seen, the fluid inlet port 103 and fluid outlet port 104 of the expansion vessel 101 are each located in a region of the wet half of the expansion vessel 101 distal to the diaphragm 105.

Optionally, and in this embodiment, the expansion vessel 101 comprises a flow path director I I I that defines a fluid flow path extending from the fluid inlet port 103 within the wet half.

In this illustrated example, the flow path director I I I comprises a tubular element. The tubular element may be provided by or comprise pipework. In this illustrated example, the flow path director I I I comprises a self-supporting structure.

In this illustrated example also, the flow path director I I I comprises a tubular element that is formed as a tubular coil. As shown, the tubular element the flow path director I I I extends from the fluid inlet port 103 and adjacent an inner wall of the expansion vessel 101. The tubular element of the flow path director I I I has a first end adjacent the fluid inlet port 103, and a second, open end 1 12. In the shown arrangement, the second, open end I 12 of the tubular element of the flow path director I I I is positioned at a substantially higher level within the expansion vessel 101 than the fluid inlet port 103. In other words, the expansion vessel 101 has a base wall providing an internal floor of the expansion vessel, and the second, open end I 12 of the tubular element of the flow path director I I I is positioned further away from the internal floor than the fluid inlet port 103; when the expansion vessel 101 is oriented as shown in Figure 3, the second, open end I 12 of the tubular element of the flow path director I I I is positioned above, and spaced from, the internal floor whereas the fluid inlet port 103 is open to the internal floor. In further other words, the expansion vessel 101 has a depth direction, and the position of the second, open end I 12 of the tubular element of the flow path director I I I is spaced from the fluid inlet port 103, in the depth direction, with the second, open end I 12 of the tubular element of the flow path director I I I closer to the diaphragm 105 than the fluid inlet port 103.

Optionally, and in this example, the tubular element of the flow path director I I I defines a plurality of orifices 1 1 3. As shown, the tubular element of the flow path director I I I has a length, and the tubular element defines the orifices I 1 3 along the length thereof. In this example, the orifices I 1 3 are regularly spaced along the surface of the tubular element; however, it is to be understood that any suitable pattern or arrangement of orifices may be utilised. Further, it is to be appreciated that orifices along the length of the tubular element may be all the same size and shape or may be of different shapes and/or sizes. It is to be appreciated also that a tubular element may not be provided with orifices and may have a single aperture provided by the second, open end I 12. Further, the flow path director I I I may comprise any suitable structure.

With the expansion vessel 101 arranged for use within a heating or cooling system with fluid circuit, as the temperature and/or pressure within the heating or cooling system rises, system fluid expands and enters the wet half of the expansion vessel 101 through the fluid inlet port 103, is directed along the hollow, tubular coil of the flow path director I I I and emerges both from the second, open end I 12 of the hollow, tubular coil of the flow path director I I I and also through the orifices I 1 3 defined in the side walling of the hollow, tubular coil of the f flow path director I I I .

Fluid exiting from the hollow, tubular coil of the flow path director I I I , and in particular fluid emerging from the second, open end I 12 thereof, enters into the wet half of the expansion vessel 101 at a level that is substantially higher than the fluid inlet port 103. This results in fluid agitation within the wet half of the expansion vessel 101 , that causes fluid entering the expansion vessel, above the fluid inlet port 103, to flow in a multitude of directions, creating turbulence, and avoiding a condition that would allow the fluid to stagnate.

According to this embodiment, system fluid enters the wet half of the expansion vessel 101 and also exits the wet half of the expansion vessel 101 through a base wall thereof. An expansion vessel 201 is shown in Figure 5, within a heating or cooling system 102 with fluid circuit. In this embodiment, the expansion vessel 201 is floor-mounted. Other differences between the expansion vessel 101 of Figure 2 and the expansion vessel 201 of Figure 5 will be described below.

The expansion vessel 201 also defines a fluid inlet port 103 for receiving circulating fluid into the expansion vessel 201 from the fluid circuit, and a separate fluid outlet port 104 for returning circulating fluid from the expansion vessel 101 to the fluid circuit. The expansion vessel 201 is divided by a diaphragm 105 into a dry half and a wet half.

In the shown arrangement, the fluid inlet port 103 and the fluid outlet port 104 of expansion vessel 201 are respectively located in a side wall and a base wall of the wet half of the expansion vessel 101 distal to the diaphragm 105.

Optionally, and in this illustrated example, the fluid outlet port 104 is provided with a first non-return valve I 14 for preventing fluid entering the wet half of the expansion vessel 201 through the fluid outlet port 104. It is to be appreciated that a similar nonreturn valve may be used with the fluid outlet port 104 of the expansion vessel of Figure 2.

Similarly, optionally, and in this illustrated example, the fluid inlet port 103 is provided with a second non-return valve I 15 for preventing fluid exiting the wet half of the expansion vessel 201 through the fluid inlet port 103. It is to be appreciated that a similar non-return valve may be used with the fluid inlet port 103 of the expansion vessel of Figure 2.

The use of the first and second non-return valves 1 14, I 15 on the fluid outlet and fluid inlet ports 1 04, 1 03 ensures that a one-way continuous fluid flow path through the wet half of the expansion vessel 201 is defined, extending from the fluid inlet port 103 to the fluid outlet port 104. It is to be appreciated that any suitable type or construction of non-return valve may be used upstream of the fluid inlet port 103 and/or downstream of the fluid outlet port 104 of the expansion vessel 101. With the expansion vessel 201 arranged for use within a heating or cooling system with fluid circuit, as the temperature and/or pressure within the heating or cooling system rises, system fluid may enter the wet half of the expansion vessel 201 through the fluid inlet port 103 and then exit the wet half of the expansion vessel 201 through the fluid outlet port 104, with this active flow avoiding undesirable stagnation of system fluid within the expansion vessel 201.

Figure 6 shows a side view of the expansion vessel 201 of Figure 5, and Figure 7 shows a cross-section of the expansion vessel 201 along line A-A shown in Figure 6. As shown, fluid inlet port 103 is located in a side region of the wet half of the expansion vessel 201 and the separate fluid outlet port 104 is located in a region of the wet half of the expansion vessel 201 distal to the diaphragm 105.

The feature of the fluid inlet port 1 03 being located in a side wall of the wet half of the expansion vessel 201 is beneficial in applications in which the expansion vessel 201 is to be floor-standing or floor-mounted, rather than wall-mounted or otherwise installed within the heating or cooling system 102.

As illustrated, although the fluid inlet port 103 is positioned in the side wall of the expansion vessel 201 , the second, open end I 12 of the hollow, tubular coil of the flow path director I I I is still at a substantially higher level within the wet half of the expansion vessel 201 than the fluid inlet port 103, and in this example that the second, open end I 12 of the hollow, tubular coil of the flow path director I I I is substantially closer to the diaphragm 105 than the fluid inlet port 103.

According to this embodiment, system fluid enters the wet half of the expansion vessel 201 through a side wall thereof and exits the wet half of the expansion vessel 201 through a base wall thereof. According to a method of installing an expansion vessel for use in a fluid circuit of a heating system or cooling system comprising a fluid circuit, an expansion vessel 101 , 201 as described herein is received, the fluid inlet port 103 of the received expansion vessel 101 , 201 is fluid ly connected to the fluid circuit, to allow fluid to flow from the fluid circuit into the expansion vessel 101 , 201 , and the fluid outlet port 104 is fluidly connected to the fluid circuit, to allow fluid to flow from the expansion vessel 101 , 201 into the fluid circuit. The fluid inlet port 103 and the fluid outlet port 104 of the expansion vessel 101 , 201 may be connected to the fluid circuit by any suitable arrangement, for example by a fluid inflow conduit and a fluid outflow conduit respectively.

When the expansion vessel 1 01 , 201 is installed for use in the fluid circuit of the heating system or cooling system, fluid within the fluid circuit can flow through the fluid inlet port into the first internal volume of the expansion vessel, and fluid within the first internal volume of the expansion vessel can flow through the fluid outlet port into the fluid circuit, the said fluid outlet port being separate from the fluid inlet port allowing a continuous flow of fluid through the first internal volume along a flow path between the fluid inlet port to the fluid outlet port.

It is to be appreciated that an expansion vessel as described herein, in which fluid enters and exits the wet half thereof through separate fluid inlet and outlet ports, addresses problems experienced with prior art expansion vessels by avoiding the stagnation of system fluid within the expansion vessel and thereby reducing the risks of bacterial growth, corrosion, reduced heat transfer, reduced efficacy of corrosion inhibitors, reduced efficacy of biocides and, in some cases, reduced water flow. Installing an expansion vessel as described herein within a heating or cooling system with fluid system therefore provides various benefits that advantageously results in improved system performance.

An expansion vessel as described herein may have any suitable dimensions, may be fabricated from any suitable material or combination of materials and may be

I I manufactured using any suitable process, method or technique or any suitable combination of processes, methods or techniques.

Thus, as described above, the present invention provides: an expansion vessel for use in a fluid circuit of a heating or cooling system, a method of installing the expansion vessel in a fluid circuit of a heating system or cooling system, a heating system comprising a fluid circuit provided with the expansion vessel, a cooling system comprising a fluid circuit provided with the expansion vessel. Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiments or examples disclosed and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims.

Claims

1 . An expansion vessel for use in a fluid circuit of a heating or cooling system, said expansion vessel comprising a first internal volume, for receiving fluid from the fluid circuit, and a second internal volume, for containing air, said first and second internal volumes being separated by a diaphragm; and

said expansion vessel defining a fluid inlet port for allowing fluid within said fluid circuit to flow therethrough into the first internal volume of the expansion vessel, wherein

said expansion vessel further defines a fluid outlet port, separate from said fluid inlet port, for allowing fluid within the first internal volume of the expansion vessel to flow therethrough into the fluid circuit;

whereby the fluid inlet port and the fluid outlet port allow a continuous flow of fluid through said first internal volume along a flow path from the fluid inlet port to the fluid outlet port.

2. An expansion vessel as claimed in claim I , wherein the fluid outlet port is located in a base wall of the expansion vessel.

3. An expansion vessel as claimed in claim 2, wherein the fluid inlet port is located in the base wall of the expansion vessel.

4. An expansion vessel as claimed in claim 2, wherein the fluid inlet port is located in a side wall of the expansion vessel.

5. An expansion vessel as claimed in any preceding claim, wherein the expansion vessel further defines an air outlet port for allowing air to exit the first internal volume of the expansion vessel.

6. An expansion vessel as claimed in claim 5, wherein the air outlet port is located adjacent the diaphragm.

7. An expansion vessel as claimed in claim 5 or claim 6, wherein the air outlet port is provided with one of: a manually-operable air vent, an automatic air vent.

8. An expansion vessel as claimed in any preceding claim, further comprising a flow path director that defines a fluid flow path extending within the expansion vessel from the fluid inlet port.

9. An expansion vessel as claimed in claim 8, wherein the flow path director comprises a self-supporting structure.

1 0. An expansion vessel as claimed in claim 8 or claim 9, wherein the flow path director comprises a tubular element.

1 1 . An expansion vessel as claimed in claim 1 0, wherein the tubular element is formed as a tubular coil.

1 2. An expansion vessel as claimed in claim 1 0 or claim I I , wherein the tubular element has a first end adjacent the fluid inlet port, and a second, open end. I 3. An expansion vessel as claimed in claim 1 2, wherein the second, open end is positioned at a substantially higher level within the expansion vessel than the fluid inlet port.

1 4. An expansion vessel as claimed in claim 1 2 or claim 1 3, wherein the tubular element defines a plurality of orifices along the length thereof.

I 5. An expansion vessel as claimed in any preceding claim, wherein at least one of the fluid outlet port and the fluid inlet port is provided with a non-return valve. 1 6. A method of installing an expansion vessel in the fluid circuit of a heating or cooling system, the method comprising the steps of;

a) receiving an expansion vessel as claimed in any of claims I to 1 5, b) fluidly connecting the fluid inlet port of the expansion vessel to said fluid circuit, and

c) fluidly connecting the fluid inlet port of the expansion vessel to said fluid circuit.

I 7. A method of installing an expansion vessel in the fluid circuit of a heating or cooling system as claimed in claim 16, wherein said heating or cooling system is a heating system.

1 8. A method of installing an expansion vessel in the fluid circuit of a heating or cooling system as claimed in claim 16, wherein said heating or cooling system is a cooling system.

1 9. A heating system comprising a fluid circuit provided with an expansion vessel as claimed in any of claims I to 15.

20. A cooling system comprising a fluid circuit provided with an expansion vessel as claimed in any of claims I to 15.