REFRIGERATING APPARATUSES

The present invention refers to an improved condensing system, in particular for refrigerating apparatuses .

Normally, condensing systems are specifically implemented for either static or ventilated uses and, particularly these latter ones, without forced convection, · show clear critical points: in fact, it must be taken into account that the coolant, at the end of the compression process, is in the overheated vapour state.

Condensing in static air, namely in natural convection not assisted by motored fans, is a solution traditionally used in household refrigerating appliances. Static condensing system are generally composed of an iron bent tube having an external diameter of about 5 mm and shaped in sections with a pitch of 50 or 25 mm with a wall of approximately 0.7 mm, with a secondary surface increased through iron wires welded to the tube or through suitable sheets with slits, in contact with the primary tube surface. The tube can be placed externally, normally on the rear side with respect to the apparatus front, or foamed, adhering to the external metallic surface of the piece of furniture. This latter variation is designated as "skin condensation" and, even with a lower efficiency, has the advantage of the aesthetic improvement and is counterbalanced by a greater total surface used for condensing. Such solution is made possible due to the low powers that must be disposed of by the condenser, since, in household refrigerations, the refrigerating powers are calibrated on the use modes.

Instead, within commercial refrigerations, the apparatuses, in particular the vertical ones, due to the use of wide glass surfaces, lights, fans and the need of taking into account the door opening frequency, are provided with much higher powers. These higher powers, due to the need of limiting the condensing surface within the encumbrance limit of the apparatus, have to be managed through forced convection. This condition implies that, therefore, in case of fan malfunction, condensing quickly reaches, under usual environmental conditions, 11000237 values that are outside the use limits, as well as the exhaust temperature of compressed gases that rises above the limit value. Therefore, before the compressor protecting device (that anyway has an automatic re-trigger, and therefore after a certain time the protecting device again provides its consent) intervenes, and before a technical intervention occurs for having realised that a malfunction condition occurred, the compressor gets to work for a period of time that cannot be defined outside its limits: working outside the limits can generate such problems as to finally impair the functionality of the compressor, normally of the airtight type.

Therefore, object of the present invention is solving the above prior art problems by providing an improved condensing system, in particular for refrigerating apparatuses, that allows limiting the condensing temperature under a both forced and natural convection, through a substantially optimised exploitation of the condensing surface.

Another object of the present invention is providing an improved condensing system, in particular for refrigerating apparatuses, that is able to avoid that, under usual environmental conditions (up to 30°C) and in case of fan malfunction, is able to keep compressor operating values within a safety area, technically defined by a closed polygon in the plane that has, as abscissa, the evaporating temperature and, as ordinate, the condensing temperature, with compression exhausting temperatures below their limit value.

The above and other objects and advantages of the invention, as will result from the following description, are obtained with an improved condensing system, in particular for refrigerating apparatuses _/ as claimed in claim 1. Preferred embodiments and non-trivial variations of the present invention are the subject matter of the dependent claims.

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:

- Figure 1 shows a rear perspective view of a refrigerating apparatus equipped with a preferred embodiment of the condensing system according to the present invention;

- Figure 2 shows a front perspective view of a structure of a refrigerating apparatus equipped with the condensing system according to the present invention; and

- Figure 3 shows a top perspective view of a component of the condensing system according to the present invention.

Obviously, for briefness, herein below the description will be omitted regarding the parts and components common to the refrigerating apparatuses and necessary for the basic operation of the refrigerators themselves, that are anyway deemed as widely known in the art, such as for example electric supply systems, systems for conditioning, compressing and channeling refrigerating gases, etc., to better point out in particular the aspects and components characterising the condensing system according to the present invention.

As known, the temperature equivalent to the condensing pressure is provided by the following relationship :

Tcond = Qcond/K*S + Tamb

where Qcond is the heat to be disposed of by the condenser, Tamb is the ambient temperature, K is the thermal exchange coefficient and S is the total working surface for such exchange.

In order to obtain the herein below stated result with the system according to the present invention, a necessary condition can be using all possible solutions suitable to reduce the thermal load of the refrigerating apparatus and the direct energy consumption in order to minimise the amount of heat Qcond that must be disposed of by the condenser. Therefore, while minimising Qcond is technically feasible, Tamb is a condition that cannot be controlled: consequently, there is the need of maximising the product K*S.

With reference to Figures 1 and 2, it is possible to note a refrigerating apparatus 1, as an example of the vertical type with double door, composed of an iso-thermal structure 2 having therein at least one refrigerating cell 4 closed by a respective door 3 and comprising, in a traditionally lower position, at least one technical room 5 adapted to contain therein at least one refrigerating system 7 operatively cooperating with a refrigerating circuit of such apparatus 1 and with the condensing system according to the present invention.

As will be clear from the following description, the best use of the condensing system according to the present invention occurs in the area of the colder door frame 9, that in the apparatus 1 with double door as an example, is the area of the central gaskets, since the incoming cold on the area comes from two counterposed sources .

As it ' is possible to note in particular from Figure 3, the condensing system according to the present invention comprises at least one condenser 11, that is preferably made with the static condenser technique, but that is suitably shaped to be contained inside the technical room 5, vented by at least one fan 13 of a preferably axial type: with such system, the convection functionality, both natural and forced, will be optimised, since under forced convection, venting is exploited during the pressing phase of the fan 13, consequently increasing the exchange coefficients with respect to the sucking venting, while in case of malfunction of the fan 13, the thermal exchange typical of the static condenser is performed.

The condensing system according to the present invention further comprises at least one "skin condenser" system 15, that is able to exploit the wide sheet surface, that is a thermally conductive material, for coating the apparatus 1. As shown in particular in Figure 1, the system according to the present invention comprises such "skin condenser" system 15 arranged on the apparatus 1 preferably, but as an example, in a rear position: obviously, the sizing of such "skin condenser" system 15 must be evaluated with respect to the condensing power to be disposed of under static conditions: taking into account that the increase of the exchange surface is linked to the global length of the tube used for making the "skin condenser" system 15, it is necessary to take into account the resulting pressure drop and, consequently, to verify whether it is necessary to make such "skin condenser" system shaped as a double parallel circuit (not shown) .

A preferred embodiment of such variation with double parallel circuits is made through two "skin condenser" systems placed on the side walls of the apparatus 1.

The condensing system according to the present invention further comprises at least one thermal exchange duct 17 arranged, at least partially, around the frame 9 of the door 3. Obviously, the placement of such thermal exchange duct 17, similarly to other previously described sections, must be evaluated for optimising the performance.

The condensing system 1 according to the present invention can further comprise at least one de-overheating system composed of at least one section 19 for a first temperature lowering for reaching the required conditions, both in air (externally before entering the insulation) and possibly in a section in contact with the external plate of the apparatus 1 before entering the frame 9, preferably of the "skin condenser" type. Similarly, a return length (not shown) , also preferably of the "skin condenser" type, is possible .

In conclusion, from the assembly of heat exchanges, it is possible to obtain, through the system according to the present invention as previously described, an operating configuration, without venting, that allows avoiding meaningful malfunctioning conditions of the compressor such as to damage the operation in a final way.

Obviously, even if the working condition that can be obtained with the system according to the present invention allows remaining under safe working conditions, such condition must not be deemed as an operating mode of a continuous type for the refrigerating apparatus.