MXPA03009658A - Cooling mechanism for refrigeration systems. - Google Patents

Abstract

An evaporator is provided having first and second independent evaporator coils. The evaporator is for use in a refrigerated display case, either open or closed, having a display length. Each of the evaporator coils is co-extensive along the display length. The evaporator coils are alternately defrosted and cooled in such a manner as to maintain a substantially constant cooling temperature throughout the refrigerated display case, even during a defrost cycle. An independent set of cooling fins is mounted to each of the evaporator coils for absorbing heat when a refrigerant, either liquid or gas, is circulated and evaporates in the evaporator coils, thus cooling the display case. A separate return is provided for each separate evaporator coil, though the two returns preferably join into a common return, thereby facilitating maintenance of a substantially constant cooling temperature.

Description

COOLING MECHANISM FOR REFRIGERATION SYSTEMS FIELD OF THE INVENTION The present invention relates, generally, to cooling systems. More particularly, the present invention relates to a cooling mechanism for cooling systems.

BACKGROUND OF THE INVENTION Refrigeration systems are important in many industries, particularly the grocery and food industry. Many such systems include a chilled display area, in which products, such as meats, chickens, etc., can be displayed, while kept at a cool temperature, to prevent their premature decomposition. Many refrigeration systems include one or more evaporators, each having a simple evaporation coil. These coils are defrosted advantageously in order to prevent the wear of the same and prevent the product from getting too cold. Thawing typically takes place three or four times daily, often at a non-critical time to the extent possible, so as not to interrupt the temperature during shopping hours. There are currently three main defrosting methods for refrigerated display cabinets. The first method involves evaporation / ventilation out of time, not assisted, where the compressor that drives the evaporator coil is simply disconnected for a period of time and thawing is achieved by exposure to ambient temperature. The second method uses evaporation, assisted by hot gas, where a hot gas is circulated in the evaporator coil, during the defrosting cycle, in order to accelerate the defrosting process. The third method uses electric defrosting, which is similar to the hot gas assisted arrangement, but uses electricity to heat the evaporator coils and promote defrosting. The first method is slow, while the second and third methods, although faster, require extra energy to effect this thawing. After a defrosting cycle, the cooling system in the refrigerated display case has to re-cool the air inside this display cabinet, so that the products can be re-cooled and kept cool. The refrigerated display case is typically maintained at a temperature of approximately 2 ° C during the cooling cycle. The temperature of a display cabinet, during a defrosting cycle, can reach up to 13 ° C. Because, after defrosting, the cooling system has to work hard to achieve its pre-cooling temperature. The system has to overcome not only the increase in ambient air temperature, but also the heating that has occurred in the product that is cooled. For meats, spoilage is a particular problem for grocery operators and other sellers. Many financial losses in meat departments are due to the decomposition of meat, caused, in large part, by defrosting cycles and not due to lack of sales. Since there is a high profit margin in meat sales, it is important that the quality of the product is maintained. In addition to the decomposition, the meat is also subject to shrinkage, due to the large proportion of water it contains. With conventional defrosting systems and their inherently large temperature swings, meats can lose a large amount of their size and weight, resulting in sales losses to the vendor, since the meat has to be reweighed and reused. packed, when it can be fully recovered. Cooling systems are known in which a plurality of evaporators are provided in a refrigerated display case, and divided into groups to cool different sections of this refrigerated display case. The evaporators each have a simple evaporator coil. These evaporators are provided in sections laterally adjacent to each other and are thawed, in groups, in cycles in alternative stages. This is done in an attempt to mitigate some of the drawbacks of thawing cycles, as discussed earlier. However, during any defrosting cycle, according to such known systems, which have evaporator groups, the section that is thawed is still subjected to a temperature significantly higher than the cooled temperature, increasing. thus the possibility of decomposition of the product in that section. Likewise, each section typically has a separate air return system, so a given section remains hot during its defrost cycle, despite the fact that the surrounding sections are cooling. Likewise, separate evaporators and compressors must be used in each section, which results in a high energy consumption. Therefore, it would be desirable to provide a cooling mechanism for cooling systems, which can more efficiently cool and defrost the evaporator coils, without large temperature swings.

SUMMARY OF THE INVENTION It is an object of the present invention to obviate or mitigate at least one of the disadvantages of the prior cooling mechanisms for cooling systems. In a first aspect, the present invention provides an evaporator for use in refrigerated display cabinets, which have a length for display. The evaporator includes first and second independent evaporator coils, along the length of display, each evaporator coil can operate in a cooling cycle and a defrost cycle, in alternate periods of time, in such a way as to maintain a substantially constant cooling temperature, through the refrigerated display case, even during a defrosting cycle. In one embodiment, the evaporator further includes first and second independent sets of cooling fins, mounted to the first and second evaporator coils, respectively, to absorb heat, when a refrigerant is circulated and evaporates in the evaporator coils, cooling so the display case. In another embodiment, the evaporator further includes an insulating element, which can be made of a plastic, provided between the first and second independent evaporator coils, to minimize the effects of a change in temperature from a defrost evaporator coil in An evaporator coil does not freeze. Each evaporator coil may include an inlet end to receive at least one refrigerant charge from an independently controlled distributor line. Each evaporator coil may include an outlet end to return the gaseous refrigerant, for subsequent condensation and recirculation to the evaporator coil from which it originates.

In a further aspect, a cooling system is provided for use in a refrigerated display case, which has a display length. The cooling system includes an evaporator, which has first and second independent evaporator coils, co-extensive along the length of display, each evaporator coil can operate in a cooling cycle and a defrost cycle, in periods of Alternate time, such as to maintain a substantially constant cooling temperature through the refrigerated display case, even during a defrost cycle. The cooling system also includes a common return, connected to the first and second coils of the evaporator, to receive the ambient air that is to be cooled by the evaporator. In one embodiment, the cooling system further includes first and second flow control valves, in communication with the first and second independent evaporator coils, respectively, to independently control the flow of refrigerant to the first and second evaporator coils, independently . The cooling system may also include first and second filters, in communication with the first and second evaporator coils, independently, respectively, to prevent, independently, impurities from entering the first and second independent evaporator coils. The cooling system may include first and second shut-off valves, in communication with the first and second independent coils, respectively, to manually stop the flow of the refrigerant to the first and second independent evaporator coils. The refrigeration system may also include first and second flow regulating devices, in communication with the first and second evaporator coils, independently, to regulate the flow of refrigerant to the first and second evaporator coils, independently. The cooling system can also include first and second distributors, in communication with the first and second coils of the evaporator, independently, respectively, to equally distribute the flow of the refrigerant to the first and second evaporator coils, independently. A controller can also be provided in the cooling system to program and control the alternate defrosting cycles of the first and second evaporator coils, independent.

In yet another aspect, a defrosting method is provided for a refrigerated display case, which has first and second evaporator coils, independent, these evaporator coils are co-extensive along a display length of the display case. refrigerated display. The method includes the following stages: cooling the first and second coils of the evaporator, independently, together, thawing the first evaporator coils, independent, while cooling the second coils of the evaporator, independently, these second coils of the evaporator, independent, cover all the length of a refrigeration system display case; cool together the first and second evaporator coils, independent; and defrosting the second independent evaporator coils, while cooling the first independent evaporator coils, these first independent evaporator coils cover substantially the entire length of the cooling system display case. In yet another aspect, a cooling system is provided for use in a plurality of refrigerated display cabinets, each with an exhibit length. The cooling system includes a plurality of evaporators, connected in parallel. Each evaporator has first and second evaporation coils, independent, co-extensive along the length of the display, with each evaporator coil being operable in a cooling cycle and a defrost cycle, in alternate periods of time, such Such as to maintain a substantially constant cooling temperature through the refrigerated display case, even during a defrost cycle. The first evaporator coils of each of the plurality of evaporators are connected to each other and define a set of first evaporator coils. The second evaporator coils of each of the plurality of evaporators are connected to each other and define a set of second evaporator coils. First and second flow control valves are provided, in communication with the sets of the first and second evaporator coils, respectively, to independently control the flow of the refrigerant to the first and second evaporator coils assemblies. Other aspects and features of the present invention will become apparent to those of ordinary skill in the art, from the review of the following description of specific embodiments of the invention, in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS Modalities of the present invention will now be described, by way of example only, with reference to the appended figures, in which: Figures 1A and IB are perspective views of conventional refrigerated display cases; Figures 2A, 2B and 2C are side, top and end views, respectively, of a conventional evaporator for use in a refrigerated display case; Figure 3 is a side view of a known configuration of evaporators, for use in a refrigerated display case; Figures 4A, 4B and 4C are side, top and end views, respectively, of an evaporator, according to one embodiment of the present invention, for use in a refrigerated display case; Figure 5 is a top view of an evaporator, according to another embodiment of the present invention, for use in a refrigerated display case; and Figure 6 is an evaporator, according to one embodiment of the present invention, shown connected to a portion of a refrigeration system, for use in a refrigerated display case.

DETAILED DESCRIPTION Generally, the present invention provides an evaporator, having first and second evaporator coils., independent. This evaporator is for use in a refrigerated display case, or open or closed, that has a length of display. each of the evaporator coils is co-extensive along the length of the display. The evaporator coils are alternatively defrosted and cooled in such a manner as to maintain a substantially constant cooling temperature, throughout the refrigerated display case, even during a defrost cycle. An independent set of cooling fins is mounted on each evaporator coil, to absorb heat when a refrigerant, liquid or gaseous, is circulated and evaporates in the evaporator coils, thus cooling the display case. A separate return path is provided for each separate evaporator coil, although the two returns are preferably joined in a common return, thereby facilitating the maintenance of a substantially constant cooling temperature. The present invention preferably provides at least one of the following advantages over known systems: energy savings; savings over time; better use of energy sources; improved product quality and product life; less water and steam in the showcases, caused by the change in temperature, due to the defrosting cycles, which result in a more pleasant experience when buying, and savings in money, due to the reduced decomposition, re-packing of the meat and the rewrap, that consume time, due to the presence of blood in the package coming from the defrosting cycles. Figure 1A is a perspective view of a conventional refrigerated display case. This refrigerated display case 100, in Figure 1A, has a display case containing a display area with a single display shelf 102. This display case 100 is shown with a close set of the removed end pieces, in order to better show some of their constituent parts. An evaporator 104 is located below the display area, to supply cooling to the display shelf 102. The evaporator 104 is also connected to a series of inlet and outlet pipes of the flow, likewise to a fan, in order to circulate the refrigerants through the evaporator and expel the heated air by means of a return. Figure IB is a perspective view of another conventional refrigerated display case. This Figure IB illustrates the fact that a refrigerated display case 106 can have a plurality of display shelves 102 in its display area. This advantageously makes better use of floor space, for example, in a grocery store, than a display case with a simple display shelf. It also allows the display of similar types of products in the same physical area and provides the retailer with opportunities for different types of cross-selling products to a consumer. Figures 2A, 2B and 2C are side, top and end views, respectively, of a conventional evaporator 108, for use in a refrigerated display case. In Figure 2A, the side view shows the cooling flaps 110. These fins 110 are mounted to an evaporator coil. This evaporator coil 112 is a cooling coil, typically comprised of metal tubing, in a snake configuration, within the evaporator 108, in order to maximize the surface area available to cool the ambient air. The evaporator coil is essentially a network of cooling tubes connected together, like a simple coil in the evaporator. The fins 110 are for absorbing heat, when a refrigerant is circulated and evaporates in the evaporator coil, cooling the display case. This refrigerant can be a liquid or a gas. The evaporator 108 typically includes a plurality of supports 114 to which the evaporator coil and the fins are mounted, in order to supply the structural integrity to the evaporator. The top view of Figure 2B shows a portion of the coil 112 of the evaporator. Figure 2B also shows a series of outlet pipes 116, which feed a simple return 118. This return 118 takes the heated air (resulting from the circulation of the refrigerant) and returns it to other portions of the cooling system that is going to cool again by the refrigerant. Figure 2C shows a plurality of rounded ends of a serpentine coil in the form of a snake. Figure 2C also shows its upper entrances to receive a refrigerant, such as a liquid refrigerant, by means of a line 120 of refrigerant. Although only one line 120 of refrigerant is shown, for purposes of simplicity of illustration, there is typically a refrigerant line 120 connected to each of the inlets. In the bottom of Figure 2C exit ends are shown to feed a return 118 or suction line. Figure 3 is a side view of a known configuration of evaporators, for use in a refrigerated display case. In Figure 3, the evaporators without identical. However, the evaporators are provided and controlled in defrosting groups. The evaporators 122 are in a first defrosting group, and the evaporators 124 and 126 are in a second and third defrosting groups, respectively. These evaporators are provided laterally adjacent to each other and are thawed in alternative staggered cycle groups, so that the evaporators immediately adjacent to each other are not thawed simultaneously. For example, the first group is thawed, then the second group and then the third group. However, during any given thawing cycle, the defrosting sections are still subject to a temperature significantly higher than the cooled temperature, thereby increasing the possibility of decomposition of the product in that section. Likewise, each section has a separate air return system, so a given section remains hot during its defrost cycle, despite the fact that the surrounding sections are cooling. Figures 4, 4B and 4C are side, top and end views, respectively, of an evaporator 128, according to one embodiment of the present invention, for use in a refrigerated display case. In Figure 4A, the side view is generally similar to that of Figure 2A. However, the evaporator 128, according to one embodiment of the present invention, includes first and second serpentines, 130 and 132, of the evaporator, independent, co-extensive along the length of the merchandiser, i.e., each one covers substantially the entire length of the display counter. Each coil, 130 and 132, of the evaporator, independently, can be operated in a cooling cycle and a thawing cycle in alternate periods of time, such as to maintain a substantially constant cooling temperature through the display case of the merchandiser of the refrigeration system, even during a defrosting cycle. The coils, 130 and 132, of the evaporator are controlled independently, as will be described later. Only the coil 130 of the evaporator is visible in Figure 4A, since the coil 132 of the evaporator is aligned upwards, directly behind the coil 130 of the evaporator. Each evaporator coil comprises a plurality of interconnected evaporator coil tubes. Such an evaporator coil is also known as a multi-circuit evaporator coil. Each tube is preferably made of a composite material of copper and aluminum. The use of copper prevents the fins from moving during the cooling and thawing cycles, as opposed to simple use using only aluminum. Aluminum is used in the compound, since it is thin and easy to work with. In a particular example of the invention, which was performed, each evaporator coil, 130 and 132 includes 24 copper tubes for a total of 48 tubes in the evaporator. In known systems, 48 tubes are provided in the evaporator, but all are controlled as a single unit. In some known systems, as discussed above, different evaporators are provided in adjacent groups, which are each separately controlled. However, that separate control does not eliminate the fact that, when one of the evaporator groups is thawed, the product in the section is subjected to thawing with a significant heating. Each of the first and second coils, 130 and 132, of the evaporator, has at least one inlet end 134 and 136, respectively. Each inlet end, 134 and 136 is for receiving at least one refrigerant charge from an independently controlled distributor line. The refrigerant can be any liquid or gaseous refrigerant, such as freon or glycol. Each of the first and second independent evaporator coils comprises an outlet end, 138 and 140, respectively, such as the return or suction lines. Each end, 138, 140, of output is to return the gaseous refrigerant to a return for condensation and subsequent recirculation to the evaporator coil, from which it originates. These inlet and outlet ends will be further described in relation to Figure 6. When an evaporator 128 is used, according to one embodiment of the present invention, the air circulates through the entire length of the display slab, through a return common, which is fed by the outputs 138 and 140. In known systems, each separate cooling section has its own return that does not mix with the other air. Thus, if a section is thawed in known systems, the ambient cooling air increases drastically in temperature. In accordance with the embodiments of the present invention, because the return is common along the entire length of the display case, the cooling temperature can be maintained more easily. In Figure 4B, the independent nature and separation of the two evaporator coils, 130 and 132, is readily apparent. Essentially, embodiments of the present invention provide the equivalent of two independent evaporators in the same physical housing. Evaporator 128 also includes first and second independent sets of cooling fins, 142 and 144, mounted to the first and second coils, 130 and 132, the evaporator, respectively. Each set of cooling fins 142 and 144, is for absorbing the heat, when a refrigerant is circulated and evaporates in the evaporator coil, thus cooling the display case of the merchandiser. Once again, the two separate sets of coils, 130 and 132, of the evaporator are shown on the right side of the figure. On the left side two separate sets of flow input lines are shown. In Figure 4C, the independent nature of the two evaporator coils, 130, and 132, are illustrated highlighted by the gap between the two coils, which are in contrast to Figure 2C, where the evaporator has a long interconnected coil. Figure 5 is a top view of an evaporator, according to another embodiment of the present invention, for use in a refrigerated display case. Since Figure 5 is very similar to Figure 4B, the common characteristics will not be discussed. In the particular embodiment of Figure 5, the evaporator 128 may include an insulator element 146, to isolate the first and second coils, 130 and 132, from the evaporator, from each other. This insulator element 14S can be, for example, made of plastic, steel or other suitable material, which can be used to isolate the two coils of the evaporator from each other, and prevent changes in one coil, which have an effect on the other coil. The insulating element 146 can be placed between the two coils of the evaporator, as illustrated in Figure 5. This insulator element is provided as an insulator in order to minimize the effects of the change in temperature of a coil of the defrosting evaporator in a Non-defrosting evaporator coil, the insulating element can also minimize the risk of moisture falling from the defrost evaporator coil to a non-defrosting evaporator coil. Although the insulator element 146 is shown in Figure 5 as covering the entire length of the evaporator 128, this is only a preferred embodiment. Sufficient insulation or separation can be provided with the insulating member 146, covering only a portion of the evaporator length. Figure 6 illustrates a cooling system including an evaporator, in accordance with one embodiment of the present invention, shown connected to a portion of a refrigeration system for use in a refrigerated display case. In Figure 6, the evaporator 128 receives an input from the two separate supply networks. The first coil 130 of the evaporator receives an inlet 134 from a refrigerant line controlled by a flow control valve, such as a solenoid valve or the solenoid 146. The second coil 132 of the evaporator receives an input at 136 from a line of refrigerant controlled by another solenoid valve 148. Each flow control valve, of the solenoid valve, in this arrangement, acts primarily as a flow control device, to control the flow of refrigerant in a refrigerant line, primarily to prevent flow in the evaporator, during the freezing cycle or the shifted cycle. Essentially the first and second flow control valves are in communication with the first and second evaporator coils, independently, respectively, to independently control the flow of the refrigerant to the first and second independent evaporator coils. Solenoid valves are available for different applications and specifications, such as from the Sporian Valve Company of Washington, Missouri. Between the end of the flow inlet of the refrigerant line and each solenoid valve 146 and 148, a filter 150 may optionally be provided. This filter 150, typically a copper filter with some kind of microscopic grid, is provided to prevent the entry of impurities into the evaporator. These impurities may be inherent in the evaporator coil tubing itself or may have been introduced at the time of installation. This filter 150 can, therefore, be considered almost as a type of insurance against inappropriate installation. Most impurities can generally be filtered and separated in the first few hours or days of operation, but the filter 150 can be advantageously kept in place to continue filtering work. Essentially, the first and second filters are in communication with the first and second evaporator coils, independently, respectively, to prevent, independently, the impurities entering the first and second evaporator coils, independent. The shut-off valves, 152 and 154 can be placed between the filter and the flow inlet of the refrigerant line, in order to provide a means by which the flow of refrigerant can be manually stopped in the case of the need for repair. or another such situation. The shut-off valve is basically a service access valve, used in case of a problem. The provision of these separate valves provides the serviceability to one evaporator coil in this evaporator, while the other evaporator coil can remain operational, thus still cooling the display case. Essentially, the first and second shut-off valves are in communication with the first and second evaporator coils, independently, respectively, to manually stop the flow of refrigerant to the first and second independent evaporator coils. Of course, if a filter is not supplied, each shut-off valve is placed between the flow inlet of the refrigerant line and the solenoid. A flow regulating device, such as a thermostatic expansion valve, 156 and 158 or TEV or TX valve, may be provided between each solenoid and evaporator coil. the TX valves regulate the flow of the refrigerant in the evaporator. The flow regulating device is generally an expansion device if the liquid is used, but can alternatively be any other type of flow regulating device. The TX valve, or the expansion valve, controls the rate of the refrigerant that passes inside the system. It can be modulated, depending on situation demands (ie the measured value compared to the desired value). Essentially the first and second devices that regulate the flow, are in communication with the first and second evaporator coils, independent, respectively, to regulate the flow of refrigerant to the first and second evaporator coils, independent. A distributor 1 to 2 can also be provided between the device regulating the flow and the evaporator coil, to equally distribute the flow of refrigerant from the device regulating the flow, within each circuit, or portion, of the evaporator coil . In the example, each distributor 160, 162 divides the refrigerant line into two lines, for feeding into the inlet 134, 136, respectively. Each distributor can be connected to the outlet of a TEV, with the outlet of the distributor preferably being machined to accept the pipe connecting the distributor to each circuit of the evaporator coil. Essentially, the first and second distributors are in communication with the first and second evaporator coils, independently, respectively, to equally distribute the flow of the refrigerant to the first and second independent evaporator coils. Expansion devices and distributors are available for different applications and specifications, such as from Sporian Valve Company of Washington, Missouri. The embodiments of the present invention can be used together in an advantageous manner. A plurality of evaporators, according to one embodiment of the present invention, can be connected together in parallel. This is advantageous, for example, in a grocery store, where a plurality of refrigerated display cabinets are placed adjacent to each other. Each of these evaporators has a first and second evaporator coils, independently controlled. However, when the evaporators are connected in parallel, the first evaporator coils of each evaporator are connected together. Similarly, the second evaporator coil of each evaporator is connected together. The plurality of evaporators are controlled by a single pair of flow control valves, such as the solenoid valves, i.e. a first solenoid valve and a second solenoid valve. This advantageously allows a plurality of evaporators, according to one embodiment of the present invention and, therefore, a plurality of refrigerated counters, in which they can be placed, to be controlled centrally by a single pair of solenoid valves. This is advantageous in comparison with currently known systems, in which a separate solenoid is required for each evaporator, or refrigerated display case. Therefore, savings in both cost and complexity are made, according to the embodiments of the present invention. In other words, according to one embodiment of the present invention, a cooling system is provided for use in a plurality of refrigerated display cabinets, each with an exhibit length. The cooling system includes a plurality of evaporators connected in parallel. Each evaporator has a first and second evaporator coils, independent, co-extensive along the length of the display, with each evaporator coil being operable in a cooling cycle and a defrost cycle in alternate periods of time, such Such as to maintain a substantially constant cooling temperature through the refrigerated display case, even during a defrost cycle. The first evaporator coils of each of the plurality of evaporators, they connect to each other and define a set of first evaporator coils. The second coils of the evaporator, each of the plurality of evaporators, are connected to each other and define a set of second coils the evaporator. First and second flow control valves are provided, in communication with the first and second evaporator coil assemblies, respectively, to independently control the flow of the refrigerant to the first and second evaporator coil assemblies. The cooling system may also include a common return, connected to the first and second evaporator coils assemblies, to receive ambient air that is to be cooled by the evaporator, but this is only a preferred feature. In the cooling system described above, the length of the display of each refrigerated display case need not be the same. If the display cabinets have a different display length, then the independent evaporator coils for each refrigerated display case will be co-extensive along the length of display for that particular refrigerated display case.

Although not illustrated in Figure 6, a cooling system, according to one embodiment of the present invention, preferably includes a controller, such as a time clock, a chronometric system or other such device. The controller is in communication with the solenoid valves, 146 and 148, to program and control the alternate defrosting of the evaporator coils. Note that, alternatively, solenoid valves or flow control valves can be controlled manually. The controller is preferably used to perform a four stage thawing method as follows. Step 1. When the controller initiates a defrost, the solenoid valve 146 closes, thus inhibiting any refrigerant from circulating in the coil 130 of the evaporator. The solenoid 148 remains open and the fans still operate. The coil 132 of the evaporator will be thawed while the coil of the evaporator 130 still cools. Keeping in mind that the evaporator coil 130 covers substantially the entire length of a display case of the refrigeration system, and, therefore, the display area of the display case remains uniformly cooled, during the coil defrosting 132 of the evaporator. Step 2. At the conclusion of stage 1 of the defrosting cycle, the solenoid valve 246 will be re-opened. At that time, both of the coils 130 and 132 of the evaporator are in a cooling mode. Step 3. After a predetermined amount of time, for example two hours, after the start of stage 1, the controller initiates a second thawing. At that time, solenoid valve 148 will close and no more refrigerant will circulate in coil 132 of the evaporator. The solenoid 146 remains open and the fans will still operate. The coil 132 of the evaporator will be thawed while the coil 130 of the evaporator still cools. Keeping in mind that the evaporator coil 130 covers substantially the entire length of the display case of the refrigeration system and, therefore, the display area of the display case remains uniformly cooled even during the defrosting of the evaporator coil 132 . Step 4. At the conclusion of stage 3 of the defrosting cycle, the solenoid valve 148 will be reopened. At that time, both coils 130 and 132 of the evaporator are in the cooling mode. The cycle of steps 1-4 preferably continues over a period of twenty-four hours. The actual amount of time spent in defrosting each evaporator coil and with both evaporator coils, in the refrigerated mode, may vary. Although there is no need to perform the thawing stages in non-peak times, this can be done if desired. Although there are some known methods in which the coils are alternatively thawed, this is known only in the content of separate evaporators of alternative thawing, in a series of evaporators, placed adjacent to each other. There is no known method in which the evaporator coils in the same evaporator are alternatively cooled and thawed. Also in known methods, there is no provision for at least one of the evaporator coils to cover the entire surface area to be cooled, in order to maintain a substantially constant cooling temperature, even during the thawing of one of the coils of the evaporator. evaporator. The cooling system may optionally include a temperature regulator or pressure to regulate the temperature and / or pressure in the cooling system. The cooling system may further include, optionally, a data logging unit, which records the temperature readings of the display case in a computer or in any other medium. The data logger unit can automatically alert an operator when the temperature goes below a defined threshold. Modes of the present invention can be used in both open refrigerated display cabinets as well as in closed refrigerated display cabinets. Likewise, the refrigerant used can be a liquid or a gas, such as freon or glycol. The embodiments described above of the present invention are tried as examples only. Modifications and alternative variants can be made in the particular modalities, by those skilled in the art, without departing from the scope of the invention, which is defined only by the appended claims.

Claims (20)

1. CLAIMS 1. An evaporator, for use in a refrigerated display case, which has a length of display, this evaporator comprises: a first and second evaporator coils, independent, co-extensive along the length of display, each The evaporator coil is operable in a cooling cycle and a thawing cycle, in alternate periods of time, such as to maintain a substantially constant cooling temperature throughout the refrigerated display case, even during a defrost cycle .
2. 2. The evaporator of claim 1, further comprising: first and second independent sets of cooling fins, mounted to the first and second evaporator coils, respectively, to absorb heat when a refrigerant is circulated and evaporated in the evaporator coils, thus cooling the display case.
3. 3. The evaporator of claim 1, wherein each of the first and second independent evaporator coils comprises an inlet end, for receiving at least one refrigerant charge from an independently controlled distributor line.
4. 4. The evaporator of claim 1, wherein each first and second independent evaporator coils comprises an outlet end for returning the gaseous refrigerant to a return site for subsequent condensation and recirculation to the evaporator coil, from which it originated.
5. 5. The evaporator of claim 1, further comprising: an insulating element, provided between the first and second evaporator coils, independent, to minimize the effects of a change Gil a. temperature from a defrosting evaporator coil, in a non-defrosting evaporator coil.
6. 6. The evaporator of claim 5, wherein the insulating element is made of a plastic.
7. 7. The evaporator of claim 5, wherein the insulating element is made of steel.
8. 8. A cooling system for use in a refrigerated display case, which has a length of display, this cooling system comprises: an evaporator, having a first and second evaporator coils, independent, co-extensive along the display length, each evaporator coil is operable in a cooling cycle and a defrost cycle, in alternate periods of time, such as to maintain a substantially constant cooling temperature through the refrigerated display case, even during a defrosting cycle; and a common return, connected to the first and second evaporator coils, to receive ambient air that will be re-filled by the evaporator.
9. 9. The cooling system of the claim 8, which further comprises: a first and second flow control valves, in communication with the first and second evaporator coils, independently, respectively, for controlling, independently, the flow of the refrigerant to the first and second independent coils.
10. 10. The cooling system of claim 9, wherein the first and second flow control valves are solenoid valves.
11. 11. The cooling system of claim 8, further comprising: a first and second filters, in communication with the first and second evaporator coils, independently, respectively, to prevent, independently, impurities from entering the first and second evaporator coils , independent.
12. 12. The cooling system of claim 8, further comprising: a first and second shut-off valves, in communication with the first and second evaporator coils, independent, respectively, to manually stop the flow of the refrigerant to the first and second evaporator coils , independent.
13. 13. The cooling system of claim 8, further comprising: a first and second flow regulating devices, in communication with the first and second evaporator coils, independent, respectively, to regulate the flow of the refrigerant to first and second evaporator coils , independent.
14. 14. The cooling system of the claim 13, in which the flow regulating devices are thermostatic expansion valves.
15. 15. The cooling system of the claim 14, in which the expansion devices are thermostatic expansion valves.
16. 16. The cooling system of the claim 8, which further comprises: first and second distributors, in communication with the first and second evaporator coils, independently, respectively, to equally distribute the flow of the refrigerant to the first and second independent evaporator coils.
17. 17. The cooling system of claim 8, further comprising: a controller for programming and controlling the alternate defrosting cycles of the first and second independent evaporator coils.
18. 18. A cooling system for use in a plurality of refrigerated display cabinets, each with an exhibit length, this cooling system comprising: a plurality of evaporators, connected in parallel, each evaporator having a first and second evaporator coils, independent, co-extensive along the length of display, each evaporator coil is operable in a cooling cycle and a thaw cycle, in alternate periods of time, in such a way as to maintain a substantially constant cooling temperature to through the refrigerated display case, even during a defrosting cycle; the first independent evaporator coils of each of the plurality of evaporators are connected to each other and define a set of first evaporator coils, and the second independent evaporator coils of each of the plurality of evaporators are connected to each other and define a set of second evaporator coils; first and second flow control valves, in communication with the sets of the first and second evaporator coils, respectively, to independently control the flow of refrigerant to the first and second evaporator coil assemblies; and a common return, connected to the first and second evaporator coils assemblies, to receive the ambient air that is to be cooled by the evaporator.
19. 19. The cooling system of claim 18, wherein the first and second flow control valves are solenoid valves.
20. 20. A method for defrosting a refrigerated display case, having first and second evaporator coils, independent, these evaporator coils are co-extensive along a display length of the refrigerated display case, this method comprises: cooling together the first and second evaporator coils, independent; defrosting the first independent evaporator coil while cooling the second independent evaporator coil; this second independent evaporator coil substantially covers the entire length of the refrigeration system display case; cool together the first and second evaporator coils, independent; and thawing the second independent evaporator coil, while the first independent evaporator coil is cooled, this first independent evaporator coil covers substantially the entire length of a display case of the refrigeration system.