REFRIGERATION METHOD

Field of the Invention

The invention relates to refrigeration equipment and especially to autonomous modular merchandiser islands of semi-vertical cabinets, and a refrigeration and cooling system for such units that use a low charge hydrocarbon gas as a refrigerant.

Description of the Technical Level

Refrigeration equipment is used for storing and displaying of various products, such as dairy products, meat products, bakery products, beverages, delicacies, fruit and vegetables, and other goods that require a cool shelf temperature.

Refrigeration equipment can be subdivided according to:

- temperature classification (e.g., cooling or medium temperature (M1 , M2, H1 , H2) cabinets; freezing or low temperature (L1 , L2) cabinets);

- connection type (e.g., remote refrigeration, when refrigeration cycle elements are usually installed in a technical room; autonomous, or plug-in, when refrigeration cycle elements are integrated into the unit of refrigeration equipment; and semi-autonomous, or semi plug-in, when refrigeration cycle elements are integrated and the device itself is additionally connected to the external cooling system);

- Equipment type (e.g., multideck cabinets - typically higher than human height, with roof to bottom ratio of 1 : 1 , semi-vertical cabinets - typically in the range of human height, with roof to bottom ratio of 1 : 3 - 2: 3; shelves with gradually increasing width; serve over and self-service display counters; freezer cabinets; freezer islands).

In the traditional remote refrigeration system, components of the refrigeration system are located remotely, compressor units consist of several compressors, whose capacity is calculated according to the required cooling demand and cooling losses in the pipelines, they are installed in a technical room, from which they are connected to the remote air condenser, and the refrigeration equipment is connected to the remote refrigeration system via network of isolated copper pipelines. To maintain cool temperature in refrigeration equipment, remote refrigeration system typically uses hydrocarbons (HFC) and carbon dioxide as refrigerants. The main disadvantages of the remote refrigeration system are large overall pipeline length, high amount of refrigerant in the system, and refrigerant leaks, which can reach up to 30% of the amount filled during the year, and the related environmental pollution; also, the necessary additional space for technical room, expensive maintenance of the system, and the inflexible arrangement of refrigeration equipment, as the pipes have to be laid up to each refrigeration unit, and high long-term costs.

The above deficiencies are eliminated by using autonomous refrigeration equipment. In the autonomous refrigeration equipment all components that are involved in the refrigeration cycle - compressor, heat exchanger, condenser, thermal expansion valve and evaporator - are installed in the refrigeration unit itself and interconnected by thin copper pipes. The refrigeration system uses effective hermetically sealed compressors; it requires a significantly lower amount of refrigerant gas (up to 80% lower than in the remote refrigeration system), its leakage rate is minimal (0-4%), so the system saves maintenance costs. The need for special refrigeration room and long copper pipelines is eliminated, which guarantees less costly system installation at the store and ensures simple maintenance. It is a simple and economical system that saves installation costs, as all components are integrated and tested on-site. This equipment ensures flexibility - it is possible to easily change the arrangement of the refrigeration equipment in the store, to replenish the site with new equipment without having to close the store. Another advantage is the easy replacement of components or piece of equipment without compromising the entire system and avoiding losses resulting from the spoilage of foodstuffs. Due to the hermetically sealed system and the near-zero gas leakage, the negative impact on the environment and global warming are significantly reduced.

Besides fluorinated gases, hydrocarbon gases such as propane R290 can also be used as refrigerants in refrigeration equipment. These are environment-friendly natural gases (Global Warming Potential - GWP = 3) having excellent thermodynamic properties. Due to flammability characteristics the regulations of the European Union and other countries limit the amount of hydrocarbon gas in a single refrigeration cycle for security purposes. For this reason, available-on- the-market refrigeration equipment that uses hydrocarbon refrigerants, such as propane R290, has a low refrigeration capacity. These are mostly low-volume, autonomic refrigerators with a small amount of hydrocarbon refrigerant, i.e., up to 150 g propane gas in a single refrigeration cycle.

There is a known cabinet described in US Patent Application No. 10 / 81 1 ,685, comprising a refrigerated space for placement of goods, a horizontal compressor, a condenser, a thermal expansion valve and an evaporator. The main disadvantages of this cabinet are the inapplicability of the refrigeration system to operate with hydro -hydrocarbon coolant, such as R290; semi- autonomous operation; also, high vibration and sound level, because one compressor is operating with two refrigeration lines; difficulties in controlling refrigeration temperature by the two evaporators, possible uneven temperatures in refrigeration equipment; double quantity of components (evaporators, thermal expansion valves, pipes, filters); problematic oil return because the refrigeration unit is installed on the roof of the equipment; high profile of refrigeration unit due to use of the horizontal compressor. The closest analogue is a modular refrigeration system using a hydrocarbon refrigerant, as described in U.S. patent application no. 14 / 210,745, comprising a refrigeration loop including a compressor, a condenser, a thermal expansion valve, a chiller and other elements necessary for the refrigerant circulation in the single refrigeration loop, and another loop / loops consisting of a circulating cooling fluid and elements necessary for circulation and heat transfer between loops. The system is designed to operate with 150 g of hydrocarbon refrigerant in a single cycle and can operate in semi- autonomous or autonomous individual refrigeration equipment. The major drawbacks of this system are: low power condensing unit; limited refrigeration capacity suitable for small (up to 1 ,25 m in length) refrigeration equipment; several circulation pumps, which cause additional electrical losses; several heat exchangers, additional losses of cold transfer in the transmission of cold in the heat exchanger; higher production costs. This type of refrigeration system is not designed to form autonomous composite formations from semi-vertical cabinets with a common cooling system.

On the market there are no fully autonomous semi-vertical cabinet systems using hydrocarbon refrigerant, such as propane R290, gases and other refrigerant liquids that would allow sufficient refrigeration capacity in islands formed on such cabinets; allowing to renovate, redesign, or expand stores, without re-equipping the entire store's refrigeration system; allowing the arrangement in the store’s central part of the user traffic flow areas, thus maximizing the use of store’s rooms without blocking other shelves and racks in the store without reducing the visibility of store space.

It is not possible to form an island of individual autonomous low profile semi-vertical equipment with individual condensing units available on the market, because:

- the narrow roof does not provide the possibility of installing a condensing unit with sufficient capacity for efficient cooling, and small condensing units are not able to efficiently cool the refrigeration unit; therefore, both autonomous semi-vertical cabinets and formations thereof available on the market are not energy efficient;

- end cases comprising usual cabinets due to the proximity of lateral portions lack an air channel for the air flow from the back side, so it is not possible to cool them by installing single condensers.

The invention addresses the above-mentioned problems related to the autonomous modular island merchandisers consisting of semi-vertical cabinets that use hydrocarbon gases as refrigerants.

Short Description of the Invention

The main point of the invention is the modular merchandiser islands, consisting of semi-vertical cabinets fitted with refrigeration circuits, designed to operate with a small amount of propane gas, having components, such as a compressor, an evaporator, and a heat exchanger installed in the case of semi-vertical cabinets, on which formation a common condensing unit is installed thereon.

Short Description of Drawings

Other features and advantages of the invention are described in the detailed description of the invention with reference to the following drawings:

Fig. 1 represents lateral section of semi-vertical cabinet and the main elements thereof (the same layout of elements is used in all semi-vertical cabinets (from the shortest to the longest lateral cabinets as well as in end case cabinets), that are connected into the island.

Fig. 2 represents air-cooled condensing unit and the main elements thereof.

Fig. 3a), b), c) represents different examples of islands formed from semi-vertical cabinets with common condensing unit.

Fig. 4 represents refrigerating and cooling scheme of the island (example with three refrigeration cycles of hydrocarbon refrigerant, such as propane R290, and one cooling fluid cycle).

Fig. 5 represents airflow control diagram in the island merchandiser.

Before submitting a detailed description of the invention with reference to embodiment example drawings, we note that identical elements are indicated by the same numerals in all the drawings.

Detailed description of the invention

It should be understood that numerous specific details are set out in order to provide a complete and comprehensive description of the embodiment example of the invention. Flowever, the skilled person will understand that the level of details of embodiment examples does not limit the embodiment of the invention, which can be embodied without such specific instructions. Well-known methods, procedures and components have not been described in detail to make sure that embodiment examples are not misleading. Furthermore, this description should not be construed as limiting the embodiment examples but as a way of their implementation only.

The invention according to the first embodiment comprises a semi-vertical cabinet according to the classification of refrigeration equipment. According to the type of connection, such cabinet can be assigned to semi plug-in cabinets but it is adapted to be used as a segmental element of an autonomous island.

Fig. 1 represents a semi-vertical cabinet (100), comprising a frame (1 10) having a bottom (1 15), side walls (120), a rear wall (125) and a roof (130) which is narrower than the bottom (1 15) - roof to bottom (1 15) ratio is from 1 : 3 to 2: 3. The cabinet can be fitted with front doors (135) and other interior elements of the cabinet (100), such as suspended shelves, dividers for goods, partitions, restraints, etc. (not shown in the drawings) required for placement of the goods. The bottom (1 15) part and the lower part of the rear wall (125) have a common cavity (140) in which a compressor (510) is mounted. The cavity (140) allows the compressor (510) to be repaired from the front of the cabinet (100). A recessed rectangular cavity (145) is formed in the upper part of the rear wall (125), in which the heat exchanger (515) is mounted. An evaporator (530) is mounted on the rear wall (125) in the inner part of the cabinet (100). Said cavities (140, 145) are formed in such a way as to use as little copper piping as possible. By connecting the compressor (510), the heat exchanger (515) and the evaporator (530) into a common system, filled with hydrocarbon gas refrigerant, a refrigerant circuit is formed. Depending on the cabinet length, it can use 1 -3 compressors (510) and 1 -3 heat exchangers (515), forming separate refrigerating circuits, but one or two of the three compressors (510) can operate depending on demand of the cold.

The preceding cabinet (100) cannot function as autonomous equipment. To cool hydrocarbon refrigerant gas, such as propane R290, a condensing unit is required which is mounted only on the cabinets (100, 100', 100") connected to an island.

According to the second embodiment of the invention, and as shown in Figures 2, 3a, 3b, 3c and 4, a condensing unit (200) of a semi-vertical cabinet (100, 100 ', 100' ') formation is disclosed, which is used for cooling down the refrigerant after the compression cycle and for removing the released heat through the cooling fluid circuit. The condensing unit (200) comprises segments (200', 200"), the number of which depends on type and size of a selected cabinet formation. The segments (200', 200") of the condensing unit (200) can be of two types: master (200') and slave (200"). The master segment (200') of the condensing unit (200) comprises a base (210) on which two condensers (410; 415) of two different lengths and capacities are mounted; the condensers (410) of higher capacity and length are fitted adjacent to the longitudinal edges of the base (210), and two condensers (415) of lower capacity and length are extending longitudinally in the center of the base (210). Condensers (415) of lower capacity are separated by partition (215). Condensers (410, 415) are cooled by fans (222), which are incorporated into fan units (220). The mentioned fan units (220) are arranged throughout the length of segments (200', 200") of the condensing unit (200) by inserting the fan (222) between the peripheral and central condensers (410, 415). The fan units (220) are mounted on the hinges (224) to facilitate the servicing of components on the base (210). The fans are separated by partitions (226) so that the air is drawn through the condensers without any turbulence and there is no mixing of the cold air with warm air, thus ensuring efficient and even heat removal through the condensers (410, 415). This solution allows using the fans (222) of lower energy consumption. The fans are covered with protective grilles (228). The condenser base (210) also includes the following elements of the cooling system: a circulation pump (420), collectors (425, 430), an expansion tank (435), a pressure gauge (440) and other elements required for the cooling fluid refrigeration cycle. Structure of the slave type segment (200") of condensing unit (200) is essentially the same as that of the master type segment (200') but it does not have a circulation pump (420), an expansion tank (435) and a pressure gauge (440). The system of copper piping is also reduced and simplified. This allows reducing the cost of the common condensing unit (200). The master segment (200') uses a variable power circulation pump (420) to provide cooling fluid circulation both in the master and slave condensing units (200', 200"), which are connected through a return (cold) and supplied (warm) coolant collectors (425, 430). This results in a significantly cheaper modular common condensing unit (200). The modular common condensing unit (200) allows convenient and easy installation of the master and / or slave segments (200', 200") on the islands (300, 300') of cabinets (100, 100', 100"), adapting them for any arrangement configuration. The base (210) of the condensing unit (200) and the sidings (601 ) of the condensing unit (200) are perforated for air permeability.

The third embodiment of the invention and Figures 3a, 3b, 3c and 5 disclose an island (300, 300') of semi-vertical cabinets for the storage and exhibition of goods and exemplary variants of the arrangement thereof.

The island (300, 300') of cabinets comprises a plurality of cabinets (100', 100") according to the first embodiment of the invention, as described above, with a high-power air condensing unit (200) mounted thereon, utilizing the resulting area and the cavity (603) between connected cabinets (100', 100"), which allows to cool both the linear cabinets (100') and their end case cabinets (100"). The island (300, 300') is fully autonomous and does not require an external secondary cooling system. The island (300, 300') of cabinets includes at least 2 cabinets (100', 100"), which are arranged adjacent to each other by the rear walls (125). The condensing unit (200) comprising master or slave segments (200 ', 200"), or both, is adapted according to the length of the formation of cabinets. As a result, the island (300, 300’) of cabinets can be extremely long and consist of modular lateral cabinets (100 ') of different lengths.

The air channel (603) is left between the two rear walls (125) for cooling of condensers (415) and is preferably about 14 cm wide. The air condensing unit (200) is installed on the roofs (130) of cabinets so that it extends along the center of the air channel (603) between the cabinets (100). The connection of cabinets (100', 100") into the island (300, 300') with a common condensing unit (200) resolves the cooling problem of end-cases (100“), which have no air gap on the rare. This solution allows the use of low profile condensers (410; 415) of up to 12 cm in height, because their length is not limited exclusively by the length of the lateral cabinet (100'). The refrigeration equipment of the island (300, 300') of cabinets comprises 1 -3 cycles of hydrocarbon refrigerant, such as propane R290, and one cycle of cooling fluid: single unit can contain from one to three cycles of hydrocarbon refrigerant, such as propane R290, depending on the selected refrigerant quantity in individual cycle (up to 500 g or up to 150 g gas per cycle). According to the fourth embodiment of the invention and Figure 4, a refrigeration and cooling diagram is shown. This diagram includes one circuit (400) of cooling fluid, such as glycol, and three circuits (500) of the hydrocarbon refrigerant, such as propane R290. The refrigeration cycle in the cabinet (100, 100', 100") begins with the compressor (510), which compresses the refrigerant gas resulting in raising their pressure and temperature. Thereafter, the refrigerant enters the heat exchanger (515), where cooling and condensing takes place, and changes refrigerant’s state from vapor to liquid while giving up the heat in the process. After passing through the heat exchanger (515), the refrigerant travels through the filter (520) to the thermal expansion valve (525), which sprays the gas into the evaporator (530), resulting in pressure reduction. The gas cools down during evaporation and causes the evaporator (530) to cool down removing the heat from the refrigeration zone of the cabinet to be cooled. The evaporated refrigerant enters the compressor (510) in vapor state, and the cycle repeats itself. The system can operate on small (up to 150 g) amounts of hydrocarbon refrigerant, such as propane R290, in one refrigeration circuit. Depending on the country-specific safety standards, the amount of refrigerant can reach up to 500 g in one circuit, thus the total number of circuits in the formation would be lower. The given refrigeration and cooling diagram depicts a system with three circuits (500) of hydrocarbon refrigerant, such as propane R290. The heat generated in each circuit (500) is removed from the heat exchangers (515) using a cooling fluid, such as water or glycol solution. Two cooling fluid tubes for warm and cooled liquid come to the heat exchanger (515). This removes the heat from the refrigerant and improves its condensation by reducing the condensing temperature. The cooling fluid is cooled down by air condensers (410; 415). The condensing unit (200) is connected to the heat exchangers (515) through the piping system, in which the cooling fluid circulates. The connection of pipes through the collectors (hubs) (425, 430) permits the formation of a single circuit of the cooling fluid line. Circulation of cooling fluid in this circuit is provided by a circulation pump (420), and expansion tank (435) is connected to compensate for the expansion of the fluid. A pressure gauge (440) is mounted near the expansion tank (435) to monitor the system pressure. The condensing unit (200) can have extremely low profile (up to 15 cm) due to arrangement of the heat exchangers (515) in the rear walls (125) of cabinets (100, 100', 100").

Although the solution described is a fully autonomous formation of semi-vertical cabinets (island), and this island is cooled by a single air (air-water) condensing unit, the island operates without connection to the secondary cooling system and uses specifically hydrocarbon gases, such as propane R290 as a refrigerant with an internal cooling cycle in which the cooling fluid is used, the island can also be connected to the secondary cooling liquid system.

The air condensing unit can be replaced by a hydrophilic condensing unit, when a hydrophilic condenser is used. Figure 5 depicts air circulation in the island (300, 300’). The cooling fluid line is cooled by the air condensers (410, 415) and the latter are cooled by the air circulating through the blades of condensers (410, 415). Fans (222) pull in the air from two directions: from the front of the cabinet and from the floor. As the warm air rises upwards, the ambient temperature at the level of condenser unit (200) is about 25°C. Cooling the cabinet (100, 100', 100") makes part of the cold air go to the floor in any case, so the air temperature at the floor level is lower (about +18°C). The air cooling process comprises two steps. The cooling fluid, being heated in a heat exchanger (515) (about +40°C), is initially supplied to the outer condenser (410), which is being cooled by air from the front of the cabinet. In this step the temperature of the cooling fluid is reduced to approximately +32°C. The cooling fluid is further supplied to central condensers (415). The lower sidings (602) and the base (210), on which the central condensers (415) are mounted, are strongly perforated, making the fans (222) to easily draw the air through the conduit (603), where cool air is taken. Cool air from the floor also cools down the compressors (510). The use of cold air, which moves from the goods placement area to the floor, helps to cool the condensers more efficiently, so after the second cooling stage the cooling fluid leaves only 2-3°C warmer than the ambient temperature, achieving optimal, stable refrigerant condensation. The chilled cooling fluid continues to flow through the heat exchangers while cooling the gas of each hydrocarbon refrigerant cycle. The better the refrigerant is cooled, the less energy is needed for compressors (510) to compress gas. The two-stage cooling in the condensing unit (200) helps reducing the power consumption by about 30%, compared to the method for cooling standard autonomous cabinet that uses one condenser.

Although the present description includes numerous characteristics and advantages of the invention together with structural details and features, the description is given as an example of the invention embodiment. There may be changes in the details, especially in the form, size and layout of materials without departing from the principles of the invention, in accordance with the widely understood definition of terms used in claims. The invention is applicable to any product and can operate in the range of any technically maintained temperatures.