A refrigerator/absorption heat pump is known to operate with a mixture consisting of an absorbent fluid such as water, and a refrigerant fluid such as ammonia.

The mixture is heated in a generator, in which the ammonia vaporizes to a greater extent than the water, to generate a vapour mixture with a high ammonia concentration; this mixture is fed to a condenser.

At the same time, a water mixture of low ammonia concentration produced in the generator by the evaporation is fed to an absorber.

In the condenser the vapour mixture of high ammonia concentration transfers heat to the outside and condenses to form a liquid mixture of high ammonia concentration.

The liquid mixture then passes though a pressure reducer device and is fed to an evaporator where, by absorbing heat from the outside, again passes into the vapour phase at high ammonia concentration.

From the evaporator the ammonia rich vapour passes to the absorber where it comes into contact with the liquid mixture of low ammonia concentration originating from the generator, and by transferring heat to the outside forms an ammonia rich liquid mixture, enabling the refrigerator/absorption heat pump to operate cyclically.

The generator in a refrigerator/absorption heat pump operating with an ammonia-water mixture is often in the form of a direct flame burner using fossil fuels.

This constitutes a limitation because fossil fuels, which in addition to being costly are very precious, may not be available in the required quantities in those places in which a refrigerator/absorption heat pump is installed.

To overcome these drawbacks certain solutions have been proposed in which the refrigerator/absorption heat pump (not of the ammonia-water mixture type) presents a generator with its shell enclosed in a casing, with heat transfer by hot or boiling water circulating through the interspace defined between the shell and the outer casing.

However these embodiments have also manifested numerous problems, due in particular to the need to construct shells with very large surfaces, to ensure transfer of the heart quantity necessary for the operation of the refrigerator/absorption heat pump. Moreover in such cases the interspace is subjected to the operating pressure of the heat vector fluid.

The technical aim of the present invention is therefore to provide a generator for a refrigerator/absorption heat pump and a refrigerator/absorption heat pump presenting said generator by which the technical drawbacks of the known art are overcome.

Within the scope of this technical aim, an object of the invention is to provide a refrigerator/absorption heat pump and a generator for this refrigerator/absorption heat pump which can be used with fuels of the most diverse types, including those fossil fuels of little value.

Advantageously, the refrigerator/absorption heat pump and the generator of the present invention are able to operate using waste energy (i. e. discarded energy from other processes) or renewable energy such as solar energy.

Another object of the invention is to provide a refrigerator/absorption heat pump which is substantially economical in terms both of plant and running costs, and is not restrained by the need to have large quantities of valuable fuel available for its operation.

A further object of the invention is to provide a refrigerator/absorption heat pump of limited environmental impact (and hence non-polluting).

A further object of the invention is to provide a generator for a refrigerator/absorption heat pump in which heat transfer to the refrigerant mixture is very intense, achieved via a surface interface of small dimensions.

This limits the plant cost of the refrigerator/absorption heat pump.

The technical aim, together with these and further objects, are attained according to the present invention by a generator for a refrigerator/absorption heat pump, and a refrigerator/absorption heat pump presenting said generator, in accordance with the accompanying claims.

Advantageously, the refrigerator/absorption heat pump and the generator for this refrigerator/absorption heat pump are very efficient.

For example, using the generator of the invention it has been found that 4 watts of hot energy (i. e. 4 watts of energy must be provided to the generator) to obtain 3 watts of cold energy (i. e. for the evaporator to absorb 3 watts of energy).

Further characteristics and advantages of the invention will be more apparent from the description of a preferred but non-exclusive embodiment of the generator and of the refrigerator/absorption heat pump presenting said generator of the invention, which are illustrated by way of non-limiting example in the accompanying drawings, in which: Figure 1 is a scheme of a refrigerator/absorption heat pump according to the present invention;

Figure 2 is an enlarged view of a generator for the refrigerator/absorption heat pump of Figure 1 according to the present invention; and Figure 3 is a schematic view of a detail of Figure 2.

Said figures show a refrigerator/absorption heat pump, indicated overall by the reference numeral 1.

The refrigerator/absorption heat pump is of the GAX type using a water/ammonia refrigerant mixture and comprises essentially a generator 2 connected to a condenser 3 (of air or water type), to a pressure reducer device 4, to an evaporator (of air or water type), to an absorber 6 (of air or water type) and to a positive displacement pump 6b.

The absorber 6 is connected to the generator 2 to transfer the water/ammonia mixture between these two components.

In detail, the generator 2 comprises, for containing a refrigerant mixture, a shell 11 comprising internally a distillation column 12 for the refrigerant mixture.

The shell 11 presents a plurality of fins 13 facilitating intense heat transfer; these fins are positioned a very small distance apart, enabling a heat transfer surface between 0.3 square metres and 1.5 square metres per TON of refrigeration capacity to be achieved.

The generator 2 also comprises a casing 14 surrounding the shell 11 to define together with this latter an interspace 15 through which a thermovector fluid can circulate to heat the refrigerant mixture.

This thermovector heating fluid is provided by a source 16; in a preferred embodiment the fluid is diathermic oil.

Advantageously, guide means 18 for the heating fluid are provided within the interspace 15 to facilitate heat transfer to the refrigerant mixture.

These guide means are arranged to impress on the heating fluid a movement inclined to the heat transfer fins 13 and comprise a helical element interposed between the casing 14 and the shell 11.

In this respect, the helical element 18 is connected to the casing 14 and to the heat transfer fins 13 and has a pitch of 10-120 millimetres.

The helical element 18 is of substantially circular cross-section with a diameter of 2-10 millimetres.

As shown in the accompanying figures, the heat transfer fins 13 extend radially to the longitudinal axis 19 of the shell 11, and extend with a helical profile from the bottom upwards.

The longitudinal axis 19 of the shell 11 defines the direction of overall movement of the heating fluid ; i. e. the heating fluid moves with substantially helical movement about the axis 19, with the heating fluid advancing overall along the axis 19.

In addition, as shown in particular in Figure 3, the source of heating fluid comprises a first circuit 21 interposed between the generator 2 and an intermediate heat exchanger 22, and a second circuit 23 interposed between the intermediate heat exchanger 22 and a primary heat source 24.

Advantageously diathermic oil circulates through the first circuit 21, whereas the primary heat source 24 can be of any type.

In a first embodiment the source 24 comprises solar panels, preferably of concentration type, to heat water which circulates through the circuit 23 and transfers heat within the heat exchanger 22 to the diathermic oil of the circuit 21.

This heated diathermic oil then heats the refrigerant mixture within the generator 2.

In a second embodiment, the source 24 comprises a heat exchanger recovering heat from other technical processes or other uses.

For example the heat may originate from the exhaust gases of a gas turbine used to heat the water circulating through the circuit 23, which then heats the diathermic oil of the circuit 21.

In a third embodiment, the source 24 comprises a heat exchanger which uses heat from natural sources, such as geothermal sources.

The heat exchanger again heats water contained in the circuit 23, this water then heating in the heat exchanger 22 the diathermic oil of the circuit 21.

In a fourth embodiment the source 24 comprises a smoke tube boiler producing hot water or steam which in the second heat exchanger 22 heats the diathermic oil of the circuit 21.

In addition to water, any suitable fluid can circulate through the circuit 23.

In contrast, the use of diathermic oil in the circuit 21 is particularly advantageous because it enables a high fluid temperature to be achieved without operating at higher than atmospheric pressure.

Advantageously, the heat sources of the aforestated examples can directly heat the diathermic oil without an intermediate heat exchanger therebetween.

In other embodiments the source 16 can consist of a diathermic oil boiler.

In addition, pressurized water can circulate through the first circuit 21, the refrigerant mixture being the water/ammonia mixture.

The operation of a generator for a refrigerator/absorption heat pump and of a refrigerator/absorption heat pump presenting said generator according to the invention is apparent from that described and illustrated, and is substantially as follows.

The source 16 provides high temperature oil which is fed to the generator 2 via an inlet manifold 25, as indicated by the arrow F1.

The diathermic oil passes through the interspace 15 guided by the helical element 18 as far as the outlet manifold 26.

The oil leaves via the manifold 26 and is again directed towards the source 16.

In this respect the circuit 21 is of closed type, the oil which circulates through it being continuously heated within the source 16 and cooled within the generator (to heat the refrigerant mixture).

The diathermic oil grazes the walls of the generator shell 11 and the heat transfer fins 13; the fins 13 are suitably very close together to form very large heat transfer surfaces, to the advantage of the heat transfer coefficient (which is very high).

The pitch of the helical element 18 is instead fairly large to enable the diathermic oil to be guided in its helical movement about the shell, but without introducing excessive pressure drops.

The operation of the refrigerator/absorption heat pump is totally similar to that of absorption refrigerators/heat pumps of traditional type.

It has been found in practice that the generator of a GAX refrigerator/absorption heat pump and the refrigerator/absorption heat pump presenting said generator of the invention are particularly advantageous because the generator and the refrigerator/absorption heat pump comprising it are extremely compact, are very flexible with regard to heat administration and very robust during start-up and shut-down transient states.

The generator for a refrigerator/absorption heat pump and the refrigerator/absorption heat pump presenting said generator conceived in this manner are susceptible to numerous modifications and variants, all falling within the scope of the inventive concept; moreover all details can be replaced by technically equivalent elements.

In practice the material used and the dimensions can be chosen at will in accordance with the requirements of the state of the art.