AU2018204034B2 - Refrigerated display unit and relative refrigerated air flow distribution system - Google Patents

Abstract

REFRIGERATED DISPLAY UNIT AND RELATIVE REFRIGERATED AIR FLOW DISTRIBUTION SYSTEM ABSTRACT 5 A refrigerated display unit is described which comprises at least one refrigerating machine; at least one refrigerated volume designed to contain products to be kept at a temperature lower than the room temperature by means of the refrigerating machine; at 10 least one technical volume intended to contain an air treatment unit, operatively connected to the refrigerating machine and comprising at least one heat exchange battery, through which a refrigerating fluid and a carrier fluid exchange heat, and a plurality of 15 fans placed at the inlet surface of the heat exchange battery; one or more doors or walls that isolate the refrigerated volume from the external environment; one or more conduits of an air system, placed in fluid connection with the heat exchange battery and arranged 20 for conveying the refrigerated carrier fluid, moved by the fans, towards the refrigerated volume. Each conduit is provided with at least one outlet opening in fluid communication with the refrigerated volume, so as to diffuse a flow of refrigerated carrier fluid, in a 25 predefined direction, within the refrigerated volume. The refrigerated display unit comprises at least one carrier fluid flow distributor device, placed at the inlet surface of the heat exchange battery and between at least two fans. The carrier fluid flow distributor 30 device is arranged to avoid the overlapping of the carrier fluid flow rates of the fans located at the sides thereof, eliminating or reducing the mutual interference of these fans.

Description

REFRIGERATED DISPLAY UNIT AND RELATIVE REFRIGERATED AIR FLOW DISTRIBUTION SYSTEM

This application claims priority from Italian

patent application 102017000063123 filed 8 June 2017,

the contents of which are to be taken as incorporated

herein by this reference.

The present invention relates generally to a

refrigerated display unit and, in particular, to a

system for distributing refrigerated air flows in a

closed refrigerated display unit.

Nowadays, particular display units provided with

refrigerating systems, usually called commercial

refrigerated counters, are very widespread. These

refrigerated display units, or commercial refrigerated

counters, are typically used in the retail sector to

display and store particular types of perishable

products. In particular, these refrigerated display

units are often used in supermarkets, canteens, etc. to

offer the opportunity to buy fresh products and keep

the products in an environment with adequate

temperature. In general, a commercial refrigerated

counter may be either open-type, that is to say,

without any solid barrier between the products

contained therein and the external environment, or

closed-type, i.e. provided with one or more doors or

walls, usually partially or completely transparent,

which isolate the refrigerated volume from the external

environment.

Regardless of the type, a commercial refrigerated

counter has the primary purpose of keeping the

temperature of the products contained therein within a predefined range of values. Many technical product standards classify refrigerated counters according to the position of such a temperature range. For positive temperature refrigerated counters and in accordance with the EN 23953-2 (2015) standard, some temperature limits are identified as follows:

1) -1/+7 0C: temperature class M2;

2) -1/+5 0C: temperature class Ml;

3) -1/+4 0C: temperature class MO.

The energy consumption of a refrigerated counter

is therefore a function of the selected temperature

range. For example, a class MO refrigerated counter

consumes more energy than a similar class M2

refrigerated counter. However, the energy consumption

of a refrigerated counter is even more dependent on the

average temperature of the products it contains. In

fact, the higher the average temperature of the

products, the lower the energy requirement of the

refrigerated counter, and vice versa. It is therefore

evident that the search for maximum energy savings in a

refrigerated counter is strictly correlated with the

increase in the average temperature of the products

contained in such a refrigerated counter.

The aforementioned energy saving strategy is

unfortunately not completely feasible, since the

products normally placed in the vicinity of the heat

exchange battery of the refrigerated counter, which

usually operates at temperatures below 00C, contribute

in greatly decreasing the average temperature. Raising

the operating temperature of the heat exchange battery

could therefore be a solution for raising the average

temperature of the products. However, this would also entail the inevitable increase in the temperature of the products in its highest values, that is to say, for those products placed far from the heat exchange battery, and therefore already at the limit with respect to the upper threshold referred to the temperature class considered.

Any reference herein to a patent document or other

matter which is given as prior art is not to be taken

as an admission that that document or matter was known

or that the information it contains was part of the

common general knowledge as at the priority date of any

of the claims.

In light of the above issues, at least some

embodiments of the present invention provide a

refrigerated display unit, in particular a system for

distributing the flow of refrigerated air into a closed

refrigerated display unit, which is able to solve the

aforementioned drawbacks of the prior art in a manner

extremely simple, cost-effective and particularly

functional.

Advantageously, some embodiments of the present

invention provide a system for distributing the flow of

refrigerated air that is able to minimise the gradient

between the hottest and the coldest points within the

refrigerated volume. A refrigerated display unit

provided with this system for distributing the flow of

refrigerated carrier fluid (air), while respecting the

limits imposed by the respective temperature class

(which may be, for example, M2: -1/+7°C), strongly

compresses the temperature range, increasing its lower

value (which in the example considered can be +5/+70C),

with the obvious increase in average temperature and the consequent decrease in energy requirements.

Accordingly, the present invention provides a

refrigerated display unit comprising:

- at least one refrigerating machine;

- at least one refrigerated volume configured

for containing a plurality of products to be kept at a

temperature lower than the room temperature by means of

the refrigerating machine;

- at least one technical volume configured for

containing an air treatment unit operatively connected

to the refrigerating machine, said air treatment unit

comprising at least one heat exchange battery, by means

of which a cooling fluid and a carrier fluid exchange

heat, and a plurality of fans placed at the inlet

surface of said heat exchange battery;

- one or more ducts of an air flow system,

placed in fluid connection with the heat exchange

battery and configured for conveying the refrigerated

carrier fluid, moved by the fans, towards the

refrigerated volume, wherein each conduit is provided

with at least one outlet opening placed in fluid

communication with the refrigerated volume, such as to

diffuse a flow of refrigerated carrier fluid, according

to a predefined direction, inside such refrigerated

volume, - wherein each conduit is divided into at least one first conduit portion with substantially vertical development, placed at a vertical wall of the refrigerated volume that is opposite the doors or walls, and into at least one second conduit portion with substantially horizontal development, hydraulically placed downstream of the respective first conduit portion, as well as above the refrigerated volume, wherein said second conduit portion is hydraulically connected to said at least one outlet opening , wherein said vertical wall is provided with a plurality of slots which put the first conduit portion in fluid communication with the refrigerated volume and, consequently, directly send part of the refrigerated carrier fluid flowing in each conduit to said refrigerated volume,

- at least one carrier fluid flow distributor

device, placed at the inlet surface of the heat

exchange battery and between at least two fans, said at

least one carrier fluid flow distributor device being

arranged to avoid the overlapping of the carrier fluid

flows of the fans placed at the sides of said carrier

fluid flow distributor device, eliminating or reducing

the mutual interference of such fans,

the refrigerated display unit being wherein it

comprises one or more doors or walls isolating the

refrigerated volume from the external environment and

wherein said flow of said refrigerated carrier fluid is

substantially parallel to the developing plane of said

one or more doors or walls in a closed configuration

and wherein each slot has a substantially horizontal

development and a width that is equal to ten times the

respective height.

Throughout the description and claims of the

specification, the word "comprise" and variations of

the word, such as "comprising" and "comprises", is not

intended to exclude other additives, components,

integers or steps.

The features and advantages of a refrigerated display unit according to the present invention will be more apparent from the following description, which is to be understood as exemplifying and not limiting, with reference to the accompanying schematic drawings, in which: figure 1 is a schematic view of a generic refrigerated display unit of the closed type made according to the prior art, in which the air flows are highlighted; figure 2 is a schematic view of a refrigerated display unit of the closed type made according to the present invention, in which the air flows are highlighted; figure 3 is another schematic view of a refrigerated display unit of the closed type made according to the present invention, in which a detail of the relative back panel is highlighted; figure 4 is a sectional view of a refrigerated display unit of the closed type made according to the present invention, in which the heat exchange battery and the relative accessories are highlighted; figure 5 is another sectional view of a

- 5a - refrigerated display unit of the closed type made according to the present invention, in which the heat exchange battery and the relative accessories are highlighted; figure 6 is a perspective view of a component of the refrigerated display unit of the closed type made according to the present invention; figure 7 is a side elevation view of the component in figure 6; figure 8 shows, for a generic refrigerated display unit of known type, the field of the velocity modules of the carrier fluid both in the plenum between the fans and the heat exchange battery and in the volume located downstream of said heat exchange battery; and figure 9 shows, for the refrigerated display unit according to the present invention, the field of the velocity modules of the carrier fluid both in the plenum between the fans and the heat exchange battery and in the volume located downstream of said heat exchange battery.

With reference in particular to figures 2 to 7, a

refrigerated display unit according to the present

invention is shown, indicated as a whole with reference

numeral 10. The refrigerated display unit 10 is

provided with at least one refrigerating machine (not

shown) that can be either incorporated in the

refrigerated display unit 10 itself or remotely

installed to operate with a plurality of separate

refrigerated display units.

The refrigerated display unit 10 is therefore

internally provided with at least one refrigerated

volume 12 configured for containing a plurality of products to be kept at a temperature lower than the room temperature by means of the refrigerating machine.

In the embodiment shown in the figures, the

refrigerated display unit 10 is of the so-called

vertical type. In the respective refrigerated volume,

one or more horizontal shelves 14 are installed on

which the products to be refrigerated are placed.

Alternatively, the refrigerated display unit 10 could

also be of the so-called "island" type, that is to say,

mainly horizontal and internally provided with or

without vertical dividing walls.

The refrigerated display unit 10 is furthermore

internally provided with at least one technical volume

intended to contain an air treatment unit operatively

connected to the refrigerating machine. As shown in

figures 4 and 5, the air treatment unit comprises at

least one heat exchange battery 16, through which a

cooling fluid and a carrier fluid (typically consisting

of air) exchange heat, and a plurality of fans 18

placed at the inlet surface 16A of such a heat exchange

battery 16, with reference to the direction of the

carrier fluid flow. The fans 18 are configured to move

both the carrier fluid to be refrigerated to the heat

exchange battery 16, and the refrigerated carrier fluid

to the refrigerated volume 12.

Irrespective of the embodiment, the refrigerated

display unit 10 is of the closed type, that is to say,

provided with one or more doors or walls 20, partially

or completely transparent, which isolate the

refrigerated volume 12 from the external environment.

Inside the refrigerated display unit 10 one or more

conduits 22 of an air flow system are provided, placed in fluid connection with the heat exchange battery 16 and configured for conveying the refrigerated carrier fluid, moved by the fans 18, towards the refrigerated volume 12.

Each conduit 22 is provided with at least an

outlet opening 24 placed in fluid communication with

the refrigerated volume 12, such as to diffuse a flow

of refrigerated carrier fluid, according to a

predefined direction, within such a refrigerated volume

12. In particular, as shown in figure 2, the outlet

openings 24 are positioned at a single door or wall 20,

so that the flow of refrigerated carrier fluid is

diffused from the respective outlet openings 24 into a

portion of refrigerated volume 12 placed at the doors

or walls 20. This flow of refrigerated carrier fluid

generates a so-called curtain or knife of air which,

among other effects, acts as a physical barrier to the

inlet of ambient air into the refrigerated volume 12 in

the condition of open doors or walls 20.

The refrigerated display unit 10 comprises at

least one distributor device 26 for distributing a flow

of carrier fluid, placed at the inlet surface 16A of

the heat exchange battery 16 and between at least two

fans 18. In order to optimise the heat exchange between

the refrigerating fluid and the carrier fluid, it is in

fact desirable that the motion field of such a carrier

fluid be as uniform as possible when the inlet surface

16A of the heat exchange battery 16 is intercepted. In

this way, the useful heat exchange surface is

maximised.

The portion of recovered power can be used to

raise the temperature of the heat exchange battery 16, with obvious advantages in terms of overall efficiency of the refrigerated display unit 10 and of a decrease in the temperature gradient of the refrigerated products. Due to a mapping of the field of motion of the refrigerated carrier fluid, which has taken place in the plenum between the fans 18 and the heat exchange battery 16, the shape of the carrier fluid flow distributor device 26 to be located at the inlet surface 16A of the heat exchange battery 16 is determined. In the embodiment shown in the figures, the carrier fluid flow distributor device 26 consists of a plate oriented according to a plane that is substantially vertical and perpendicular to the inlet surface 16A of the heat exchange battery 16.

Figure 8 shows, for a generic refrigerated display

unit of known type, the field of the velocity modules

of the carrier fluid (air) both in the plenum between

the fans and the heat exchange battery and in the

volume located downstream of said heat exchange

battery. The areas indicated with R represent the

higher speeds, while the areas indicated with B

represent the speeds close to zero. Because of the

mutual interference between the flow rates processed by

each individual fan, in the plenum there are sums or

subtractions of flow of the carrier fluid. This

phenomenon involves a maldistribution of the total flow

of carrier fluid which intercepts the inlet surface of

the heat exchange battery. A maldistribution of the

total flow of carrier fluid implies that some parts of

the heat exchange battery do not carry out any heat

exchange (inlet speed equal to zero).

Figure 9 instead represents the field of the velocity modules of the carrier fluid (air) for the refrigerated display unit 10 according to the present invention, once again measured both in the plenum between the fans 18 and the heat exchange battery 16, and in the volume placed downstream of such a heat exchange battery 16. The presence of one or more carrier fluid flow distributor device 26 prevents the overlapping of the carrier fluid flow rates of the fans

18 located at the sides of each carrier fluid flow

distributor device 26, eliminating or reducing the

mutual interference of these fans 18. The result, shown

in figure 9, is a better distribution of the velocity

of the carrier fluid at the inlet surface 16A of the

heat exchange battery 16. Obviously, a variable number

of carrier fluid flow distributor devices 26 can be

applied according to requirements.

Each conduit 22 is divided into at least one first

conduit portion 22A with substantially vertical

development, placed at a vertical wall 28 of the

refrigerated volume 12 that is opposite the doors or

walls 20, and into at least one second conduit portion

22B with substantially horizontal development,

hydraulically placed downstream of the respective first

conduit portion 22A, as well as above the refrigerated

volume 12. The second conduit portion 22B is

hydraulically connected to the outlet opening 24.

The vertical wall 28 is provided with a plurality

of slots 30 with substantially horizontal development,

which put the first conduit portion 22A in fluid

communication with the refrigerated volume 12 and,

consequently, directly send part of such a refrigerated

carrier fluid flowing in each conduit 22 to said refrigerated volume 12. Each slot 30 preferably has a width equal to about ten times the respective height, as shown in figure 3. Even more preferably, each slot

30 has a width of about 20 mm and a height of about 2

mm.

Still preferably, a plurality of slot 30 rows,

superimposed to each other and spaced according to a

predefined dimension A, is provided on the vertical

wall 28, wherein each row of slots 30 comprises a

plurality of slots 30 which are side-by-side and

arranged along a substantially horizontal axis. Even

more preferably, such a dimension A is about 50 mm. The

first conduit portion 22A, on the other hand, has a

passage cross section having a width preferably equal

to about 60 mm.

The particular drilling of the vertical wall 28

contributes to the decrease of the temperature gradient

between the coldest point and the hottest point of the

refrigerated volume 12. The size and the shape of each

slot 30, combined with the specific dimensioning of the

first substantially vertical conduit portion 22A, allow

splitting the flow of refrigerated carrier fluid in

such a way that each product, independently of the

shelf 14 on which it is placed, exchanges the correct

amount of thermal energy with the refrigerated carrier

fluid. In particular, the products that are in sight,

and which are therefore also subject to irradiation,

benefit from an additional convective exchange due to

the effect of the front air curtain or knife. In

contrast, products that are in shadow with respect to

the radiating surface are only partially involved in

the flow of refrigerated carrier fluid. For irradiating surface it is meant the surface belonging to the external environment with respect to the refrigerated display unit 10 and which exchanges heat by irradiation due to a temperature difference. Typically, the irradiating surface consists of the walls, floors and/or ceilings of the room in which the refrigerated display unit 10 is located.

In a generic closed-type refrigerated display

unit, that is to say, provided with doors like that in

figure 1, ventilation is generally reduced since it is

assumed that the barrier effect is not carried out by

the refrigerated carrier fluid curtain, as in an open

refrigerated display unit, but by the doors themselves.

Even if this corresponds to what has been

experimentally found, the refrigerated carrier fluid

curtain produced by reduced ventilation tends to assume

a curved shape that does not adequately brush all the

product to be refrigerated (see figure 1, where the

vortices of air between the curtain of refrigerated

carrier fluid and the door are highlighted). This means

that, at the same temperature of the refrigerated

carrier fluid, some products are warmer than others,

with the obvious consequence of increasing the overall

gradient of the stored goods.

In the refrigerated display unit 10 according to

the present invention, the fans 18 have been sized so

as to exploit the doors or walls 20 as straightening

surfaces of the air curtain or knife, which is

vertically guided, uniformly impinging the products to

be refrigerated (see figure 2). In other words, the

flow of the air curtain or knife provided by the outlet

openings 24 is substantially parallel to the developing plane of the door or wall 20 in its closed configuration. In this way, the swirling movements that occur in the refrigerated volume area between the air curtain or knife and the doors or walls of traditional refrigerated display units are eliminated or at least reduced (see figure 1).

In addition to the suitably perforated vertical

wall 28, the element which allows the use of the doors

or walls 20 as straightening surfaces of the air

curtain or knife is the sizing of the flow rate of the

refrigerated carrier fluid (air), i.e. the quantity and

type of fans 18 installed on the refrigerated display

unit 10. The optimal flow range is calculated as a

compromise that allows:

1) on the one hand, obtaining sufficient verticality of

the air curtain or knife by using the doors or walls 20

as straightening elements of the flow lines; and

2) on the other hand, not excessively increasing the

effect of convective exchange against such doors or

walls 20 and, consequently, not excessively increasing

the electric consumption of the motor of fans 18.

In fact, the flow rate of the refrigerated carrier

fluid is sized so as to use the doors or walls 20 as

straightening surfaces for creating the air curtain or

knife.

Preferably, the optimum flow rate of the

refrigerated carrier fluid (air), with the passage

sections of the conduit 22 and of the slots 30, is

obtained in a velocity range of such a refrigerated

carrier fluid ranging from 1.65 m/s to 2.0 m/s, where

the speed is measured at the intake grid of fans 18.

For flow rates smaller than the design ones, the fluid vein detaches from the doors or walls 20, starting to

"sway" and losing the efficiency of standardizing the

temperature of the products.

In particular, the open-type refrigerated display

units of the known type, that is, the open-type wall

mounted refrigeration counters of the known type,

generate a refrigerated carrier fluid flow at the

opening such as to generate a frontal vertical air

curtain which is capable of separating the internal

environment from the external environment.

Specifically, the flow must be dimensioned in a

way, on the one hand, as to avoid excessive turbulence

with the external environment (in the case of too high

speed and/or flow), and on the other hand to prevent

the breaking of the air curtain and of the relative

fluid barrier (in case of too low speed and/or flow).

In closed refrigerated display units of the known

type, that is to say in closed wall-mounted

refrigeration counters, the presence of the closing

door has made the need to create a fluidic barrier

useless, since the barrier is defined by the door

itself.

However, the generation of a refrigerated carrier

fluid is provided which, however, performs only the

cooling function and therefore not necessarily the

generation of the air curtain acting as a fluid

barrier, if not in the brief moments of opening the

door. Figure 1 shows an example of the flows of the

refrigerated carrier fluid in a closed display unit.

Conventionally, if it is assumed that the flow

rate of a refrigerated carrier fluid in an open display

unit is equal to 1, the flow rate of a refrigerated carrier fluid in a closed display unit of the same size, geometry, external environmental conditions and performances is around 0.5 - 0.6.

The flow rate of refrigerated carrier fluid

generated in the refrigerated display unit, according

to the invention, is dimensioned so as to be

significantly greater than that of a closed display

unit of a known type, but also than that of an open

display unit of a known type, with the same dimensions,

geometries, external environmental conditions and

performances.

In particular, if it is assumed that the flow rate

of a refrigerated carrier fluid in an open display unit

is equal to 1, and that the flow rate of a refrigerated

carrier fluid in a closed display unit of known type is

around 0.5 - 0.6, according to the invention, with the

same dimensions, geometries, external environmental

conditions and performances, the flow rate is around

1.3 - 1.4.

In this way, as already described, the increased

curtain tension, by ensuring a good quality in the heat

exchange with the goods and the door 20, is used as a

current rectifier for verticalizing and stabilizing the

air curtain.

It has thus been seen that refrigerated display

unit according to the present invention achieves the

objects described above.

The refrigerated display unit of the present

invention thus conceived is susceptible to many

modifications and variants, all falling within the same

inventive concept; furthermore, all the details can be

replaced by technically equivalent elements. The materials used, as well as the shapes and dimensions, may in practice be of any type according to the technical requirements.

The protective scope of the invention is therefore

defined by the appended claims.

Claims (8)

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. Refrigerated display unit comprising:

- at least one refrigerating machine;

- at least one refrigerated volume configured for

containing a plurality of products to be kept at a

temperature lower than the room temperature by means

of the refrigerating machine;

- at least one technical volume configured for

containing an air treatment unit operatively

connected to the refrigerating machine, said air

treatment unit comprising at least one heat exchange

battery, by means of which a cooling fluid and a

carrier fluid exchange heat, and a plurality of fans

placed at the inlet surface of said heat exchange

battery;

- one or more ducts of an air flow system, placed in

fluid connection with the heat exchange battery and

configured for conveying the refrigerated carrier

fluid, moved by the fans, towards the refrigerated

volume, wherein each conduit is provided with at

least one outlet opening placed in fluid

communication with the refrigerated volume, such as

to diffuse a flow of refrigerated carrier fluid,

according to a predefined direction, inside such

refrigerated volume,

- wherein each conduit is divided into at least one

first conduit portion with substantially vertical

development, placed at a vertical wall of the

refrigerated volume that is opposite the doors or

walls, and into at least one second conduit portion

with substantially horizontal development,

hydraulically placed downstream of the respective first conduit portion, as well as above the refrigerated volume, wherein said second conduit portion is hydraulically connected to said at least one outlet opening , wherein said vertical wall is provided with a plurality of slots which put the first conduit portion in fluid communication with the refrigerated volume and, consequently, directly send part of the refrigerated carrier fluid flowing in each conduit to said refrigerated volume,

- at least one carrier fluid flow distributor device,

placed at the inlet surface of the heat exchange

battery and between at least two fans, said at least

one carrier fluid flow distributor device being

arranged to avoid the overlapping of the carrier

fluid flows of the fans placed at the sides of said

carrier fluid flow distributor device, eliminating or

reducing the mutual interference of such fans,

the refrigerated display unit being wherein it

comprises one or more doors or walls isolating the

refrigerated volume from the external environment and

wherein said flow of said refrigerated carrier fluid is

substantially parallel to the developing plane of said

one or more doors or walls in a closed configuration

and wherein each slot has a substantially horizontal

development and a width that is equal to ten times the

respective height.

2. Refrigerated display unit according to claim 1,

wherein each carrier fluid flow distributor device

consists of a plate oriented according to a plane that

is substantially vertical and perpendicular to the

inlet surface of the heat exchange battery.

3. Refrigerated display unit according to claim 1, wherein the outlet openings are positioned at a single door or wall, such that the refrigerated carrier fluid, delivered by said outlet openings, forms an air curtain or knife whose flow is substantially parallel to the development plane of the door or wall in its closed configuration.

4. Refrigerated display unit according to claim 1,

wherein each slot has a width of about 20 mm and a

height of about 2 mm.

5. Refrigerated display unit according to any one of

the preceding claims, wherein a plurality of slot rows,

superimposed to each other and spaced according to a

predefined dimension, is provided on the vertical wall,

wherein each row of slots comprises a plurality of

slots which are side-by-side and arranged along a

substantially horizontal axis.

6. Refrigerated display unit according to claim 5,

wherein said predefined dimension is equal to about 50

mm.

7. Refrigerated display unit according to any one of

the preceding claims, wherein the first conduit portion

has a passage cross section equal to about 60 mm.

8. Refrigerated display unit according to any one of

the preceding claims, wherein the flow of said

refrigerated carrier fluid is obtained in a velocity

range of such a refrigerated carrier fluid ranging from

ranging from 1.65 m/s to 2.0 m/s, where the speed is

measured at the intake grid of said fans, so as to use

the doors or walls as straightening surfaces for

creating the air curtain or knife.