Container for fast refrigeration and preservation of milk

A container for fast cooling of milk and its preservation and transportation at an optimal temperature (0.degree.-4.degree. C.) comprises a body (11) consisting of an internal recipient (12) defining a tank (13) for containing the milk and an intermediate shell (14) surrounding the internal recipient (12) and connected in a sealed manner therewith to define between the recipient (12) and the intermediate shell (14) a jacket (18) designed to contain liquid at a freezing temperature lower than a predetermined preservation temperature. The container is covered with an insulating external shell (20). Ducts (30) for circulation of the refrigerating fluid are arranged in the jacket (18). There can also be provided means (48,49,54) for the controlled input of milk up to thermal contact with the refrigerating walls of the recipient (12) and means (35) for mixing the milk in the tank (13) during cooling and preservation.

BACKGROUND OF THE INVENTION 
The present invention relates to a container for the fast cooling of milk 
and its preservation at an optimal temperature from the moment of milking 
and during transportation between the production location and the 
utilization location, e.g. dairies. 
Milk production areas are often located in mountainous locations difficult 
to reach, far from inhabited centers and without electric power. A typical 
case is that of sheep, goat, buffalo et cetera stock farms which use 
pastures located in remote areas not reachable by large automotive 
vehicles equipped with refrigeration units but which supply the best 
products. 
Preservation of the milk at surrounding temperature from the moment of 
milking to the beginning of transportation and during travel, sometimes 
long, from the production area to the dairies involves proliferation of 
bacteria which is incompatible with the applicable standards covering the 
quality of food products and in particular milk. 
Observation of these standards therefore involves the impossibility of 
utilizing pasture zones at a great distance from the dairies if the latter 
are not served by the electric power distribution network or independent 
electric power generators are not available. 
The general purpose of the present invention is to obviate the above 
mentioned shortcomings by supplying a container for the transportation of 
milk which would be capable, once carried into the production location, of 
cooling the milk in the time periods required by standards at a 
predetermined optimal preservation temperature (between approximately 
0.degree. and 4.degree. C.) without being dependent upon local power 
sources nor on permanently connected independent refrigeration units and 
transporting it at this temperature, held virtually constant, to the 
processing places. 
Another purpose of the present invention is to provide a container in which 
the milk could be subjected to a first substantial cooling during its 
inlet into the container before making contact with the milk already 
refrigerated and present in the container. 
Another purpose of the present invention is to provide a container which 
would hold the milk at a virtually uniform temperature both during cooling 
and during preservation thereof. 
SUMMARY OF THE INVENTION 
In view of the above mentioned purposes it was sought to provide in 
accordance with the present invention a container for fast cooling of milk 
and holding it at a predetermined optimal preservation temperature and 
characterized in that it would comprise a body consisting of an internal 
recipient defining a tank for containing the milk and an intermediate 
shell surrounding externally the internal recipient and connected in a 
sealed manner therewith to define between the recipient and the 
intermediate shell a jacket designed to contain a liquid with freezing 
temperature below a predetermined preservation temperature in such a 
manner as to define the wall of the recipient as a refrigerating wall and 
in which ducts for the circulation of refrigerating fluid are arranged in 
the jacket with the container being covered with an external insulating 
shell. 
With respect to ordinary non-refrigerating containers, the container in 
accordance with the present invention would be capable of extending 
considerably and with no drop in quality the total period of time elapsing 
between production of the milk and its delivery to the dairies and thus 
capable of utilizing for production even pastures located in remote and 
not readily accessible places while increasing the productivity of the 
region. 
The greatest period of time available for preservation of the milk while 
observing the qualitative limits placed by health standards also allows 
making collection with lesser frequency with obvious financial benefits. 
In comparison with conventional refrigerating containers which are 
connected permanently to special refrigerating units, the container in 
accordance with the present invention offers the advantage of operation in 
areas without power with no need to transport the refrigerating unit and 
thus avoid possible damage to the latter because of vibrations and blows 
typically induced by running over ill- or unpaved roads. This container 
also offers considerable operating advantages when used in areas where the 
electric power does not provide certainty of continuous delivery ensuring 
correct operation of the systems even in case of power failure. 
The container in accordance with the present invention also presents the 
advantage that the temperature of the milk already refrigerated and 
present in the tank is not significantly influenced by the subsequent 
input of further quantities of milk having a temperature near that of 
milking thus ensuring virtually constant temperature of the milk once it 
has cooled.

DETAILED DESCRIPTION OF THE INVENTION 
In FIG. 1 reference number 10 indicates a milk container comprising a body 
11 consisting of an internal recipient 12 defining a tank 13 for 
containing the milk and an intermediate shell 14 surrounding the recipient 
12 externally. 
The recipient 12 and the shell 14 can be made for example of stainless 
steel conforming to the standards on containers for food stuffs and are 
connected together in a sealed manner advantageously by means of welding 
15 opposite their respective upper portions 16, 17. Between the recipient 
12 and the shell 14 is defined a tank 18 designed to be filled with a 
quantity of liquid having a freezing temperature and melting heat such as 
to allow refrigeration of the milk and holding it at the optimal 
preservation temperature. 
The freezable liquid contained in the tank 18 and taken to the solid state 
constitutes refrigerating thermal capacity for the milk contained in the 
container 10. 
The optimal milk preservation temperature to avoid proliferation of 
bacteria incompatible with applicable quality standards for the product is 
virtually between 0.degree. and 4.degree. C. and therefore the liquid 
constituting the thermal capacity can be a solution having a composition 
such as to display a freezing temperature virtually between -11.degree. C. 
and 0.degree. C. and melting heat sufficient to ensure refrigeration of 
the milk starting from a temperature of approximately 
35.degree.-37.degree. C. upon milking down to the preservation temperature 
(0.degree.-4.degree. C.) in a time period between 15' and 3 hours after 
the end of milking with an input flowrate of the milk into the container 
equal to approximately 10-40% of its capacity per hour or in approximately 
15' after input of the milk into the container depending on the percentage 
of filling thereof. Conservation of the milk at the temperature of 
0.degree.-4.degree. C. is ensured for at least 12 hours and even up to 
over 72 hours. 
Advantageously the solution used will be chosen with a composition such as 
not to display volumetric expansion upon passage from the liquid to the 
solid state. But even aqueous solutions of various composition having a 
minimum expansion upon freezing of less than 5% and preferably less than 
2% can also be used. 
The tank 18 is sized in such a manner that in case of use of a solution 
having volumetric expansion upon freezing the quantity of liquid necessary 
for obtaining the thermal performance required fills its available volume 
in a quantity not greater than approximately 90-98% while providing a 
virtual expansion chamber above permitting absorption of the increased 
volume of the solution resulting from the change of state. 
Between the internal recipient 12 and the intermediate shell 14 there can 
be provided spacing elements 19 for strengthening the structure and made 
of thermal insulation material to avoid the creation of thermal bridges 
between the two walls. 
The body 11 of the container 10 is covered with an external insulating 
shell 20 consisting for example of a layer 21 of foamed polyurethane 
covered by a steel sheet 22 having the same characteristics as those used 
for the recipient 12 and the shell 14. 
In accordance with a preferred embodiment the body 11 of the container is 
open above to facilitate cleaning operations of the tank 13 and the 
insulating shell 20 comprises a closing element 23 for the tank. The 
element 23 is mobile with respect to the container and is insulated and 
applicable thereon with the interposition of sealing gaskets 24 between 
them and the body 11 to avoid outflow of milk from the tank during 
transportation. On the container is provided a mouth 26 which is designed 
for input of the milk into the tank and is equipped with a filter element 
27 which can be placed in communication with a reservoir 28 for metering 
of the incoming flow of milk. The reservoir 28 has advantageously between 
1/15th and 1/25th of the capacity of the container 10 and preferably equal 
to approximately 1/20th thereof and can be applicable to the mouth 26 only 
during filling operations and thus equipping the mouth with an appropriate 
filling cap or it can be applied in a permanent manner and in this case it 
is itself equipped with appropriate closing means. 
In the embodiment shown in FIG. 1 the mouth 26 for input of the milk is 
arranged on the fixed portion of the upper covering of the container. As 
an alternative, the mouth 26 can also be provided opposite the moving 
closing element 23 of the tank as shown diagramatically in broken lines in 
FIG. 2. 
Inside the jacket 18 are housed ducts 30 belonging to a coil circuit 31 
designed for circulation of refrigerating fluid, e.g. freon gas, designed 
to take the liquid contained in the jacket to a temperature lower than its 
freezing temperature. 
The circuit 31 can be connected through appropriate quick connections 32, 
33 respectively for input and outlet of the refrigerating fluid to an 
external refrigerating unit of known type (not shown) powered by the 
electric power system or an electrical power generating unit. 
In the jacket 18 can be provided appropriate fins (not shown because their 
possible configurations are readily imaginable to one skilled in the art) 
for improvement of the heat exchange and greater cooling speed of the 
freezable liquid in the jacket so as to speed the cooling of the milk. 
Appropriate fins can be provided if desired also on the surface of the 
ducts 30. The presence of these fins involves the creation Of a high 
number of thermal bridges between the cooling ducts and the wall of the 
recipient 12 in order to utilize the absorption capacity of the heat of 
all the frozen liquid and not only the surface layer in contact with the 
wall 12. 
Advantageously the circuit 31 consists of two sections connected in 
parallel and the ducts 30 are arranged inside the jacket 18 with density 
decreasing from below upward. In addition, the cooling circuit is 
configured geometrically in such a manner that the path of the 
refrigerating fluid develops from below so as to provide progressive 
freezing of the liquid in the jacket from below upward and allow running 
towards the virtual upper expansion chamber. 
For the purpose of avoiding possible overpressure in the jacket 18 due to 
any expansion of the liquid during freezing, in the top portion of the 
jacket are provided known valve means, indicated diagramatically by 34, 
for removal of air from the jacket upon filling thereof with the freezable 
liquid. 
In accordance with another innovative feature of the present invention the 
container is equipped with a system for controlled input of the milk into 
the tank, and into thermal contact with the refrigerating wall 12 in the 
form of a thin film 52 (FIG. 2). 
In a first embodiment as shown in FIGS. 1 and 2 the milk input system 
comprises a connector 47 for connection between the mouth 26 and a duct 48 
for milk distribution. The duct 48 develops above the tank 13 virtually 
along the entire internal periphery of the recipient 12 and is fixed by 
known support means to the side walls thereof in such a manner that there 
remains between the duct and the side walls a thin passage sufficient to 
permit a run-through of the milk along the walls as better explained 
below. 
Along the duct 48 is uniformly distributed a plurality of openings 49 
directed as shown in FIG. 2 in such a way as to permit outflow of the milk 
upwards in the direction of the wall of the recipient 12. The openings 49 
have their axis 50 forming with the perpendicular to the side wall of the 
recipient an angle between 30.degree. and 75.degree. and preferably around 
45.degree.. 
During the milk loading phase the milk is input to the metering reservoir 
28 at a temperature virtually equal to that of milking. Thence it flows 
through the mouth 26 into the connector 47 and then into the distribution 
duct In the duct 48 the milk outflows through the opening 49 upwards in 
the direction of the wall of the internal recipient 12 to then run 
downward through a thin slot 51 existing between the duct and the side 
wall to form a liquid film covering the wall. Advantageously the clearance 
of the slot 51 is sufficiently small to permit generation of a milk film 
52 thinner than 2 mm and preferably around 0.2 mm. This slot can be 
created e.g. by merely drawing the duct near to the wall with provision of 
fixing means thereto sufficiently spaced from each other. The milk film 52 
during its descent along the refrigerated wall of the tank between the 
duct 48 and the free milk surface of the cold milk already present in the 
container cools rapidly because of its thinness down to a temperature near 
that of preservation. Therefore, successive inputs of milk do not cause 
significant changes in the temperature of the milk input previously and 
already refrigerated. 
The container is also equipped in accordance with the present invention 
with means of mixing the milk in the tank so as to accelerate cooling and 
allow it to hold a temperature as uniform as possible both during cooling 
and during preservation and extending in this manner the preservation 
phase. 
In a preferred embodiment the mixing means consist of a propeller agitator 
35 rotating at low speed (on the order of 10 to 50 RPM) immersed in the 
tank 13 and connected electrically with a power supply battery indicated 
diagramatically by 36. Advantageously the agitator 35 is arranged in the 
tank in a virtually central position. The propellers of the agitator 35 
are configured in such a manner as to generate a circulation of the milk 
in the tank characterized by an ascending flow in the central portion of 
the tank and descending flows near the walls. In this manner the milk film 
52 descending along the walls of the tank, after having reached the free 
surface, is induced to continue the descent along the walls as shown 
diagramatically by 53 to be further cooled. 
Activation of the agitator 35 during the preservation phase can 
advantageously be automatically controlled by means of a timer 42 or by 
means of signals sent to a control unit (diagrammed by 42) by appropriate 
temperature sensors 44 arranged inside the tank 13 when they detect in 
predetermined portions of the tank temperature differences of the milk 
with respect to the optimal preservation temperature. In addition, the 
agitator 35 can be operated in such a manner as to provide continuous 
mixing during the milk loading and cooling phases and intermittent mixing 
during preservation at the predetermined temperature. 
In a variant embodiment shown in FIG. 3 the mouth 26 for input of the milk 
into the tank 13 and the reservoir 28 are arranged in registry with the 
axis of rotation of the agitator 35. 
In this embodiment the controlled milk-input system comprises at least one 
distribution duct 54 fixed to the agitator shaft to rotate integrally 
therewith. The duct 54 is directed towards the cooling walls 12 of the 
tank 13. The portion 55 of the shaft included between the reservoir 28 and 
the moving duct 54 comprises within it a passage 56 to allow the milk to 
flow from the tank to the distribution duct. The latter displays at its 
end 57 appropriate openings for spraying the milk against the cooling wall 
12. Once it has made contact with this wall the milk descends along it 
virtually in the form of a film while cooling rapidly as mentioned above 
with reference to the first embodiment. 
The container comprises in addition a duct 37 for unloading the milk and 
extending between a first opening 38 for outlet of the milk from the tank 
13 and a second opening 39 for its unloading to the exterior and equipped 
with an insulated closing plug 40. 
To facilitate flow of the milk from the container its bottom 41 and the 
duct 37 are inclined downwards in the direction of the opening 39 at an 
angle between 5.degree. and 55.degree. and preferably around 10.degree.. 
The container in accordance with the present invention can comprises a 
recirculating circuit 58 equipped with an operating pump 59 as diagrammed 
in broken lines in FIG. 3. This circuit connects the drain opening 39 with 
the input mouth 26 and is advantageously usable for washing the container. 
The circuit 58 is also applicable to the container in accordance with the 
embodiment of FIG. 1. The container 10 can also be equipped with known 
means 45 for fixing on a vehicle indicated generically by 46 and which 
could be e.g a trailer drawn by a tractor. 
It is clear that the sizing of the cooling system depends on the thermal 
performance required and the climatic conditions in which the container 
will be used. By way of example, for a container operating at an outdoor 
temperature up to 50.degree. C. and for which is required cooling of the 
milk in a maximum time period of approximately one hour after the end of 
milking from the milking temperature (approximately 35.degree.-37.degree. 
C.) down to the preservation temperature (0.degree.-4.degree. C.) and 
holding this temperature steady for 12 to 72 hours until delivery of the 
milk to the processing location, the quantity of freezable liquid 
contained in the jacket can be equal to 25 to 80% of the maximum quantity 
of milk contained in the tank 13 and preferably around 60% thereof. 
By connecting the cooling circuit of the container with a refrigerating 
unit before departure from the dairy to bring the freezable liquid to the 
solid state, the container can be taken to the milk production location 
where the milk will be inlet to the tank 13 of the container and cooled 
and held at the preservation temperature until return of the container to 
the dairy for delivery without the quality characteristics of the milk 
undergoing undesired changes. 
Naturally the above description of an embodiment applying the innovative 
principles of the present invention is given merely by way of example and 
therefore is not to be taken as a limitation of the patent right claimed 
here. For example, for mixing the milk in the tank, in addition to or as 
an alternative to the helical agitator, there can be used the 
recirculating circuit 58. 
In addition, on the container can be arranged removable means 29 as shown 
in broken lines in FIG. 1 for shielding the external surface from solar 
rays. Appropriate handles 25 can be provided on the element 29 to 
facilitate movement.