This invention concerns the field of refrigeration machines for use with a very wide range of applications, from the refrigerator for commercial use to refrigeration plants for industrial use.

As is well known, the aforementioned machines operate by means of a cycle that includes a phase of evaporation of a fluid, a phase during which the refrigerating effect occurs, and a subsequent phase of recompression of the fluid, from which the heat produced by said compression is removed before re-emitting it into circulation for the subsequent cycle to be carried out.

The operation of fluid compression is currently carried out by means of compressors of a mechanical or centrifugal type, or, much more often, by reciprocating-pistons, and the energy lost due to the delivery of the compressor significantly jeopardizes the overall energy balance of the different refrigerating machines.

Furthermore, in the case of reciprocating-piston compressors, due to the need to lubricate the cylinder/piston interface during their relative reciprocating movement, it is practically impossible to prevent minute particles of lubricant from mixing with the refrigerating liquid while it is compressed, and these droplets then finish up deposited on the various organs of the refrigeration machine, including the absorber, forming a layer that creates numerous disadvantages, such as alteration of the overall coefficient of thermal transmission.

The inventor of the present idea has attempted to provide a solution which, besides improving the overall efficiency of the refrigeration machine, also eliminates the above problem with the lubricant.

To this end, he has conceived a refrigeration plant that operates through a cycle that includes the evaporation and the subsequent recompression of a fluid, the latter operation being carried out using a compressor, characterized by the fact that said compressor is of liquid jet type.

The functional diagram of the system is shown in figure 1 ; here the arrows indicate the direction of circulation of the refrigerating fluid and also of the auxiliary ones for desuperheating 5 and the absorber 3.

The same type of system is shown in figure 2; whereas here the absorber also includes the tank for the refrigerating fluid in liquid state on its lower part.

The individual component parts have not been represented in more detailed form, as they are all well known to experts in the field. In the figures, in order to better visualize the operation of the plant, the sections of the circuit in which the fluid of the refrigerating cycle is in its liquid and vapour states are indicated by "I" and "v" respectively.

In the version described in fig. 1 , as can be noted, there is a receiver tank 1 in the refrigeration plant, which contains the fluid in the liquid state inside it.

Said fluid is sucked and sent to an absorber 3 by means of a circulation pump 2, preferably of centrifugal leakproof type (here the desired cooling of a fluid takes place, through an exchanger 8), and to a liquid jet compressor 4; these are placed in parallel with each other, appropriately distributing the capacities reaching them, taking account of the functional and dimensional characteristics of the refrigeration cycle adopted.

The part of fluid that is ejected at high speed from the nozzle of the liquid jet compressor 4 takes on the function of motor fluid here and, after sucking the fluid in vapour state from the absorber 3 through the Venturi effect, it draws it, compressing it in the diffuser 4 and returning it to the liquid state, between a desuperheater 5 that removes its excess heat before the fluid itself once again reaches the receiver tank 1 to begin the subsequent

cycle.

An energy saving of approx. 40%com pared with a conventional type of system has been found when using a system according to this invention. It must also be emphasized that, in the refrigeration system in question, maintenance requirements prove to be considerably reduced, as the compressor is of a type that works without any mechanical moving parts, and as the duration of the latter proves to be practically limitless.

Some possible modifications to improve the refrigeration system described so far will be mentioned below. These modifications also appear in the enclosed figure.

For instance, the absorber 3 can be connected to the receiver tank 1 via an "equalizing" conduit 6, so as to balance the pressures existing in the absorber 3 and in the receiver tank l.

The absorber 3 can also be provided with a T capacity regulator fitted in the branch 7 that connects the absorber 3 with the feeding conduit coming from the pump 2, in order to keep the liquid level constant in an absorber that is preferably of the "flooding" type.

The functional diagram of another system according to the invention is shown in figure 2, with certain improvement modifications made.

In this system the absorber unit 11 also functions as a receiver tank for the refrigerating fluid in its liquid phase, the unit 11 being of the type well known to technicians in the field, where the two stages of the fluid, liquid and aeriform, exist laid out in two layers, one above the other.

The operation of the system is conceptually identical to that already described by figure

1 , but the inventor has made provision to improve its efficiency by making it fit the new operating situation. For instance, he has fitted a servo by-pass 9 which varies the capacity of the fluid sent by the pump 2 to the compressor 4, a capacity which, obviously,

varies or can vary over time according to operating conditions, this by-pass can for example be piloted on the basis of the final temperature of the outcoming fluid to be cooled by an exchanger 8.

Furthermore, another servo organ 10 has been provided to regulate the back pressure existing at the lower end of the desuperheating unit 5 of the fluid already brought back to the liquid state. This back pressure does in fact vary with variation in the regulated refrigerating capacity as described above, and therefore this organ 10, which can also operate basing itself upon an equalizer system piloted on the basis of pressure, keeps it constantly regulated according to operational requirements.

In both the plants described it is obvious that a technician from the field can fit all the control and interception organs most suitable for the individual operating situation.

There are many further modifications that a technician in the field could make to the refrigeration plants represented schematically in the figures, but these modifications, if included within the concepts expressed by the enclosed claims, do not lie outside the scope of the protection conferred by the present patent application. The examples shown are neither binding nor limited therefore in relation to other types of construction.

The totally different conception of the system according to the invention with respect to a traditional plant is that, with the same refrigerating power obtained, the motive energy expended is considerably less.

The very low compression ratio of the relative cycle compared with a traditional cycle in fact serves to highlight its lower energy consumption.

Furthermore, the plant can generate cooling sources at high, medium and low temperature.

The refrigerating unit described is built in a monobloc version, and the dimensions are

very contained; on-site installation is very convenient for the purposes of keeping the costs of constructing a station down.

The absence of vibrations makes the base supporting it very economical; furthermore, the unit has only to be connected to the circuit of the fluid to be refrigerated and to the electrical energy supply necessary for the leakproof pump and for the control panel for all the auxiliary electrical equipment.