Patent Application
20200224937
The present invention refers to a refrigerating unit of a dispenser of refrigerated products. In general, the present invention refers to systems for loading or unloading a refrigerating substance, compression machines, plants or systems characterized in that the refrigerating substance is inflammable.
In particular, the present invention refers to multi-circuit heat exchangers.
Automatic refrigerated dispensers are made for selling products of any type and nature stored at a controlled temperature which is lower than the ambient temperature.
Therefore, it is necessary to thermally insulate the products from the outside environment through a refrigerated room insulated with insulating materials and almost hermetically closed, to avoid seepages of external hot air, keeping inside the products to be stored at a desired temperature.
In order to do so, in almost all cases, a refrigerating system is made, based on a cycle known as steam compression cycle. The refrigerating circuit is mainly composed of four major components: a compressor, a heat exchanger, known as condenser or gas cooler, a lamination member and a second heat exchanger, known as evaporator.
The operating principle of a refrigerating system with steam compression cycle consists in circulating, by sucking and then compressing through a compressor, for example a rotary, centrifugal, screw-type piston, etc., a refrigerating fluid contained in the refrigerating circuit, in order to increase the pressure of the refrigerating fluid sucked at gaseous state.
The refrigerating fluid exiting the overheated compressor through the compression is then passed through a high-pressure heat exchanger, condenser, to be cooled at a temperature below its saturation temperature, changing its state, from gas to liquid, at the expense of another fluid like water or simply ambient air.
The liquid refrigerating fluid exiting the condenser is then passed through a lamination member, for example, capillary tube, thermostatic valve, ejector. In practice, such lamination member is a throttling device which determines a high and calculated pressure drop downstream thereof.
After this, the liquid refrigerating fluid enters into another heat exchanger, evaporator, being subjected to an expansion due to the sudden widening of the passage section and a cooling due to Joule-Thomson effect.
The refrigerating fluid, evaporating inside the evaporator, absorbs energy from surrounding air through natural or forced convection through fans. The evaporator is always placed in the room to be cooled or within narrow thermal contact therewith.
The thermodynamic cycle ends when the evaporated refrigerating fluid at gaseous state exiting the evaporator is sucked by the compressor.
Currently, the most used refrigerating fluids in the refrigerating circuits of automatic refrigerated dispensers are HFC, Hydro-Fluoro-Carbons, such as R134a and R404A, characterized by good thermodynamic features.
However, a few among the most used Hydro-Fluoro-Carbons have flammability and toxicity problems, due to their high Global Warming Potential, GWP, with consequent greenhouse effect.
In order to solve this problem, since 1 Jan. 2015 E U Regulation n. 517/2014, also called F-GAS, has been in force, and provides for the prohibition of use for new apparatuses for refrigerating R404A, starting from 2020, and R134a, starting from 2022.
Currently, in compliance with F-GAS regulations, refrigerating fluids alternative to HFC and strongly requested in the refrigeration world are the totally natural gases, HC, namely gas produced by the anaerobic decomposition of organic material, Hydro-Fluoro-Carbon, HFC-based fluorinated refrigerating gases, Hydro-Fluorine-Olefin, HFO-based gases, carbon dioxide, CO2.
However, carbon dioxide is already for a small part used in automatic dispensers, but due to some critical aspects, such as high operating pressures and low energy efficiency at moderate temperatures, it is not seen as final and favorable solution with respect to HC and HFO.
The problem of automatic dispensers is that, inside the refrigerated room containing the products to be stored, there are several motors and actuations which, during their operation, can create electric arcs.
At the same time, HC and HFO refrigerants are deemed highly inflammable the former, and moderately inflammable, the latter, like also any refrigerating fluid classified according to the American ASHRAE standards of safety designation and classification of refrigerants falling within the categories “Class 2”, “Class “A2L” and “Class 3”.
Generally, in automatic dispensers equipped with refrigerating systems of the direct expansion type, the evaporator is placed inside the refrigerated room and the refrigerating fluid inside the evaporator directly produces the requested cooling work. In such automatic dispensers, in case of leakage of refrigerating fluid from the evaporator, the refrigerating fluid, directly passing inside the refrigerated room, could form a potentially inflammable atmosphere.
The prior art is given by patent EP-B1-2712416 dealing with a two-fluid apparatus to recover and regenerate a refrigerant in a system comprising a first and a second recovering and regenerating circuits, each one having a recovery duct and a delivery duct arranged respectively to recover a used refrigerant and to deliver a regenerated refrigerant in the system. The apparatus comprises: a compressor for compressing one or the other used refrigerant; a common evaporator; a common vacuum pump associated with the evaporator; a condenser and a collecting tank for each refrigerant; programming means to selectively activate the first or the second recovering and regenerating circuits, according to a user's choice between a first or a second refrigerant; valves on the recovery duct and pressure measuring means actuated by the programming means in order to selectively actuate the valves, so that, when a user chooses the first or the second refrigerant, the pressure measure determines the correct or wrong choice of the refrigerant by the user and, respectively, opens or blocks the valves.
The disclosure of patent EP-B1-271241 allows recovering and regenerating refrigerants having a different nature and mutually incompatible. Moreover, it allows avoiding the contamination between two different refrigerants during the recovering and regenerating operations in two different air-conditioning systems.
The disclosure of patent EP-B1-2712416 is the starting point to solve the problem present in automatic dispensers, namely, in case of leakage of a refrigerating fluid from the evaporator, the possible passage of refrigerating fluid directly inside the refrigerated room and the consequent formation of a potentially inflammable atmosphere.
Object of the present invention is solving the above prior art problems, by providing a refrigerating unit of a dispenser of refrigerated products which safely uses HC, namely totally natural gases produced by the anaerobic decomposition of organic material, as refrigerating fluid in refrigerating circuits for automatic dispensers.
A further object is making a hydronic refrigerating system, also known as Chiller refrigerating system, using water or other heat-transfer substances to transport the thermal energy, both for heating and for cooling.
A further object is using a hydronic refrigerating system composed of two physically separate circuits: a traditional refrigerating circuit composed of compressor, condenser, lamination member and evaporator; and a circuit with a heat-transfer fluid such as water or an antifreeze solution.
A further object is using a hydronic refrigerating system composed of a primary circuit containing a refrigerating fluid HC, or any other refrigerating fluid deemed inflammable, in which the evaporator is not used to directly cool the refrigerated room, but to refrigerate the heat-transfer fluid of a secondary circuit.
The above and other objects and advantages of the invention, as will appear from the following description, are obtained with a refrigerating unit for a dispenser of refrigerated products as claimed in claim 1. Preferred embodiments and non-trivial variations of the present invention are the subject matter of the dependent claims.
It is intended that all enclosed claims are an integral part of the present description.
It will be immediately obvious that numerous variations and modifications (for example related to shape, sizes, arrangements and parts with equivalent functionality) can be made to what is described, without departing from the scope of the invention as appears from the enclosed claims.
The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the enclosed drawings, in which:
With reference to
Advantageously, the refrigerating unit 3 comprises at least one primary evaporator 9 in common with respect to the refrigerating fluid and the heat-transfer fluid and at least one secondary heat exchanger 10 with respect to the heat-transfer fluid and to the refrigerated products in the room 2.
With reference to
In particular, the primary circuit for recovering and regenerating the refrigerating fluid is composed of a compressor 4, a condenser 5, at least one fan of the condenser 6, a dehydrating filter 7, a lamination member 8 and the primary evaporator 9.
With reference to
The pump 12 for circulating the heat-transfer fluid is placed in the room of the primary circuit, while the secondary heat exchanger 10 is placed inside the room 2 for cooling and keeping the products at controlled temperature.
Preferably, the refrigerating fluid is composed of totally natural gases, HC, namely gas produced by the anaerobic decomposition of organic material, Hydro-Fluoro-Carbon, HFC-based fluorinated gases, Hydro-Fluorine-Olefin, HFO-based gases, carbon dioxide, CO2, while the heat-transfer fluid is composed of water or of an antifreeze solution.
The present invention is based on a refrigerating system to be installed in automatic refrigerated dispensers to prevent fires and explosions from occurring with the use of potentially dangerous refrigerating gases.
The refrigerating system is composed of two physically separate circuits. A primary circuit placed in an open area of the automatic dispenser to avoid creating a potentially inflammable atmosphere allows cooling a heat-transfer fluid contained in a secondary circuit adapted to cool the storage area of the automatic dispenser.
Typically, an automatic dispenser comprises a room refrigerated through a refrigerating unit. In the refrigerated room the products being sold are stored, such as beverages, snacks, sandwiches, packaged food products. The refrigerating unit allows cooling and keeping the products being sold in the refrigerated room.
The refrigerating unit is composed of a compressor, a condenser, at least one fan for cooling the condenser, a dehydrating filter, a lamination member, a primary evaporator, a secondary heat exchanger, at least one fan for the secondary heat exchanger and a circulating pump for the heat-transfer fluid.
The refrigerating unit is made of two different sections: a hermetically sealed primary circuit, in which the potentially inflammable refrigerating gas, sued for cooling the heat-transfer fluid, circulates through pipes, typically made of copper; and a secondary circuit, in which the heat-transfer fluid circulates to guarantee the cooling of the refrigerated room.
The primary circuit is composed of a compressor, a condenser, at least one fan for cooling the condenser, a dehydrating filter, a lamination member, a primary evaporator.
The primary evaporator is placed in a suitable room of the automatic dispenser, the compressor room, open towards the outside environment, so that, in case of possible leakages of the inflammable refrigerating fluid, there is an adequate air circulation, natural or forced through a fan, to exclude the possibility of having a potentially inflammable atmosphere in a confined area.
The secondary circuit is composed of a secondary heat exchanger, at least one fan for the secondary heat exchanger and a circulating pump for the heat-transfer fluid.
The circulating pump for the heat-transfer fluid is placed in the room of the primary circuit, while the secondary heat exchanger is placed inside the refrigerated room for cooling and keeping the products at controlled temperature.
The secondary circuit has the primary evaporator in common with the primary circuit. For this, the primary evaporator is composed of a single heat exchanger equipped therein with two physically separate circuits, respectively travelled by the refrigerating gas and by the heat-transfer fluid.
In the primary circuit, through the compressor, the pressure of the refrigerating fluid sucked at gaseous state is increased. Exiting the compressor, the refrigerating fluid, overheated through compression, crosses the condenser being subjected to a cooling below its own saturation temperature, at the expenses of another fluid, such as water or simply ambient air. In such way, the refrigerating fluid changes status, from gas to liquid. When exiting the condenser, the liquid refrigerating fluid crosses a dehydrating filter and a lamination member. Such lamination member is a throttling device adapted to generate a certain big pressure drop, in this case a capillary tube, a thermostatic valve or an ejector. Then, the liquid refrigerating fluid enters the evaporator to be expanded and cooled due to the Joule-Thomson effect, due to a sudden widening of the passage section inside the evaporator. When exiting the evaporator, the refrigerating gas is then sucked by the compressor to end the thermodynamic cycle.
In the secondary circuit, through a circulating pump, the heat-transfer fluid crosses the secondary circuit of the evaporator composed of pipes made of copper or flexible plastic material, being subjected to a cooling. Then, the heat-transport fluid reaches the heat exchanger placed inside the refrigerated room, getting cooled through conduction and convection, natural or forced through fans, to guarantee that the products are kept at the desired temperature.
The refrigerating unit in two different sections guarantees the chance of using any type of potentially inflammable refrigerating gas in automatic refrigerated dispensers.
In fact, in case of leakages of refrigerating gas in the primary circuit, in the closed refrigerating cell an inflammable atmosphere cannot be formed.
The secondary circuit containing the heat-transfer fluid is composed of a circulating pump, a heat exchanger in common with the primary system, an evaporator to cool the heat-transfer fluid and a heat exchanger for the convective or conductive thermal exchange to be placed inside the refrigerated room for cooling and keeping the products at a controlled temperature.
The evaporator of the primary circuit is made through any building type, with welded-brazed plates, with coaxial tubes, with micro-channels, etc., suitable for a thermal exchange of the Gas-Liquid or Liquid-Liquid type without mixing the fluids.
The circulating pump of the heat-transfer fluid can be controlled by a simple control of the ON/OFF type or, in order to guarantee the best efficiency of the thermodynamic system, can be controlled and managed by an electronic system, which, depending on the thermal load to be dispensed of in the refrigerated cell, changes the number of pump revolutions and therefore the flow-rate of the heat-transfer fluid.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102017000085669 | Jul 2017 | IT | national |
This application is a U.S. National Phase application of International Application No. PCT/IT2018/000074, filed on May 18, 2018, which claims priority to an Italian Patent Application No. 102017000085669, filed on Jul. 27, 2017, the entirety of which is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IT2018/000074 | 5/18/2018 | WO | 00 |
