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TECHNICAL FIELD

The present invention relates to a thermal-refrigerating absortion machine for household use intended for the simultaneous production of hot and cold water starting from hot water. More particularly, the present invention relates to a machine which, once it is connected to a water supplying source such as, for instance, a boiler or a water-heater, is able to simultaneously feed different pipelines with cold water, e.g. for air conditioning use, and with hot water, e.g. for sanitary use.

The invention may be mainly applied in the field of manufacturing of thermal-mechanical machines.

BACKGROUND ART An absortion machine for industrial use is known in the art, which is used, for instance, for refrigerating overheated waste water produced by various kinds of industries.

Such machine is essentially based upon the use of a heat exchanger or generator having a first exchange circuit fed by steam. This steam has a temperature which is generally comprised between 125°C and 130°C and comes from, e.g. a steam boiler.

Furthermore, the heat exchanger has a second exchange circuit, acting as evaporator, inside of which lithium bromide in water solution is present; this solution has an evaporation temperature similar to the temperature of the steam circulating inside of the first circuit.

The evaporated gas of lithium bromide and water is then fed into a first circuit of an exchanger/absorber, thereby

absorbing a given quantity of heat from the liquid (water) flowing inside of the second circuit of the same, thus refrigerating said liquid.

This kind of machine has a typical industrial use; therefore it has remarkable dimensions and capacity, and it requires a generator for producing steam at a temperature of 125°C-130°C, which is necessary for the evaporation of the lithium bromide and water solution.

DESCRIPTION OF THE INVENTION The present invention aims to provide for an absortion machine for producing cold and hot water starting from a fluid, e.g. water, having a relatively low temperature, said machine being then suitable for being connected to a normal boiler for household use producing water at a temperature comprised between 60°C and 90°C, said machine having extremely reduced dimensions and being then suitable for small users such as, for instance, home users.

This is achieved by a thermal-refrigerating absortion machine having the features disclosed in the main claim. The dependent claims describe some particularly advantageous forms of embodiment of the invention.

According to a feature of the invention, the machine condenser houses a filtration unit constituted by stainless steel meshes having a cusp shape in order to enhance the formation of drops.

According to another feature of the invention, the evaporator houses a filtration unit constituted by stainless steel meshes having a non-cuspidated shape suitable for holding the fluid in its liquid phase and to allow the passage of the fluid in its vapour phase.

According to a further ^' feature of the invention, the whole process inside of the refrigerating circuit is carried out under vacuum conditions, i.e. at a pressure of about 100

Pa and, in any case, lower than 1000 Pa.

According to an important feature of the invention, the absortion machine comprises, inside of the refrigerating circuit, a solution of chemical elements having an evaporation temperature comprised between 60°C and 85°C.

The fact of using the technical measures as described above, as well as of using as refrigerating fluid a solution of this kind allows a series of important advantages to be achieved. In fact, since the evaporation temperature of this solution is comprised between 60°C and 85°C, an ordinary boiler for home users, which produces water at a temperature comprised between 60°C and 85°C, may be used in order to obtain the evaporation of this solution. The passage of the evaporated solution into the absorber allows then to obtain water at a temperature comprised between 7°C and 12°C, which may be used for air conditioning purposes inside of a domestic room.

According to a form of embodiment of the invention, the refrigerating solution is constituted by lithium bromide, water and other alcohols, e.g. either methanol, or ethanol or monoethilenic glycol.

According to another form of embodiment of the invention, which is particularly advantageous from an economical point of view, the solution is constituted by a mixture of hydroxydes, e.g. 50% water, 25% natrium hydroxyde, 20% potassium hydroxyde and 5% cesium hydroxyde.

The use of the latter solution is very advantageous both from the economical and the technical points of view, since this solution is capable of dissipating a higher quantity of heat on the condenser compared to the lithium bromide solution, since the molecular transmission rate is higher. According to an advantageous form of embodiment of the

invention, the machine further comprises a secondary thermal exchange circuit, which allows relatively cold water to be heated; by way of example water at a temperature of 15°C may be heated up to a temperature of about 45°C to 50°C, said water, being then available for sanitary use.

ILLUSTRATION OF DRAWINGS Other features and advantages of the invention will become apparent by reading the following description, given as a non-limiting example, with the help of the figures shown in the annexed drawings, in which:

- fig. 1 shows a simplified layout of a first form of embodiment of a thermal-refrigerating machine according to the invention;

- fig. 2 shows a simplified layout of a second form of embodiment of a thermal-refrigerating machine according to the invention;

- fig. 3 shows a working diagram of the machine according to the invention, the refrigerating solution being constituted by a mixture of water and lithium bromide; and

- fig. 4 shows a working diagram of the machine according to the invention, the refrigerating solution being constituted by a solution of hydroxydes. DESCRIPTION OF A FORM OF EMBODIMENT In figure 1, reference sign 10 generally indicates an absortion machine for household use for the simultaneous production of hot and cold water starting from relatively hot water produced by a boiler 11.

Said boiler 11 is generally constituted by a common boiler for household use capable of producing, at its outlet α, hot water at a temperature comprised between 80°C and 90°C; this water circulates, by means of a pump 13, inside of a coil placed inside of a first heat exchanger/generator 12, and it

comes back at a temperature comprised between 70°C and 78°C at connector β of boiler 11.

According to the invention exchanger/generator 12 contains a solution whose evaporation temperature is comprised between 60°C and 90°C, said solution being then made to evaporate by means of thermal exchange with the fluid circulating within said coil at a pressure lower than 1000 Pa.

According to a form of embodiment of the invention, the solution contained inside of the exchanger/generator 12 is constituted by lithium bromide, water and other alcohols, e.g. methanol and/or ethanol and/or monoethilenic glycol.

According to another form of embodiment of the invention, which is particularly advantageous from an economical point of view, the solution is constituted by a mixture of hydroxides, e.g. 50% water, 25% natrium hydroxyde, 20% potassium hydroxyde and 5% cesium hydroxyde.

The vapour coming out from connector γ of generator 12 is fed into a first circuit of an exchanger 14 acting as a condenser and whose operating way will be later described in detail.

The condensed fluid is then fed through a pipe, a solenoid valve 15 and a pump 16, to the inlet δ of another exchanger 17, acting as a refrigerator and whose operating way will be later described in detail. The fluid coming out from connector ε of exchanger/refrigerator 17 is then fed, through a solenoid valve 18, inside of an evaporator 19 comprising a nebulizer 20 and a filtration unit 21; thereafter the fluid is fed back by means of pump 16. Said filtration unit 21 is generally constituted by a high density stai-nless steel mesh, suitable for allowing the passage of vapour and for holding liquids.

The upper portion of evaporator 19 communicates, by means

of a large diametre pipe, with the upper portion of absorber 27, in order to allow the passage of vaporized solution between these elements.

In working conditions, the fluid has a temperature of about 5°C in correspondence of connector 6 and a temperature of about 12°C in correspondence of connector ε of the exchanger/refrigerator 17.

Within refrigerator 17 there is a second circuit inside of which circulates water for air conditioning, which enters (see arrow A) the refrigerator at a temperature of about 12°C and which is available for the user (see arrow B) at a temperature of about 7°C, thereby achieving one of the purposes ot the invention.

According to a particularly advantageous form of embodiment of the invention, machine 10 comprises a secondary circuit which is capable of heating water for sanitary use from a temperature of about 15°C up to a temperature of about 48°C.

The water at a temperature of 15°C, coming from a suitable supplier (see arrow C) , is fed through a suitable pipe within an exchanger 24, which acts as stocking boiler of hot water for sanitary use.

Inside of exchanger 24 a thermal exchange occurs which will be later described in detail, and the water is heated up to a temperature of about 48°C; then, the water is available for sanitary use at an outlet represented by arrow D.

In the case where the water is heated up at a temperature higher than 50°C, a temperature-rise valve 25 is switched on, which discharges the overheated water through a suitable outlet E.

The heating circuit of the sanitary water comprises a coil housed inside of exchanger/boiler 24; the water circulates within said coil as fed by pump 23.

The water flow in this circuit is as follows.

Starting from outlet connector φ of the coil on exchanger

24 the water is fed, through a suitable pipe, into the second circuit of exchanger/condenser 14, inside of which it absorbs heat by means of a thermal exchange with the fluid circulating within the first circuit of the same, which is constituted by the solution evaporated inside of exchanger/generator 12.

The water heated inside of exchanger 14 is then fed to the inlet connector of the first exchange circuit of a further exchanger 12, whose operating way will be later described in detail; thereafter, the water crosses said pump 23 and from here it is fed to the inlet connector η of the coil placed inside of exchanger/boiler 24.

The machine according to the invention is completed by a circuit for reinstating the refrigerating solution.

This circuit comprises an exchanger/absorber 27 provided with a nebulizer and a conical filtration unit 26 under which there is the condensed refrigerating solution.

According to the invention, said conical filtration unit 26 is constituted by a cuspidated stainless steel mesh, in such a way as to enhance the formation of condensation drops.

Furthermore the nebulizer, as well as nebulizer 20 housed in the evaporator 19, is constituted by a device comprising a single cylindrical nozzle which spreads the solution inside of respective absorber 27 or evaporator 19 in such a way as the solution is spread over the whole mesh surface of the respective filtration unit.

This involves important advantages in respect of the known solutions, which provide for a distributor having a series of nozzles spraying from above the coil of a tube nest exchanger.

A pump 28 is connected to the outlet connector λ of absorber 27; said pump feeds the solution, at a temperature of

about 44°C, to a divisor constituted by a pair of solenoid valves 29, 30.

In operation, about 90% of the solution crosses solenoid valve 30 and is fed to the second exchange circuit of exchanger/condenser 22, in which it absorbs heat from the water circulating inside of the first exchange circuit of said condenser 22.

Now, the heated solution coming out of condenser 22 is fed to the nebulizer placed inside of exchanger/absorber 27. About 10% of the solution is used, starting from solenoid valve 29, for feeding the solution which is present inside of exchanger/generator 12.

For this purpose, after having crossed solenoid valve 29, the solution having a temperature of 44°C crosses in succession the first circuit of an exchanger pair 32, 33, within of which it absorbs heat in the way which will be later described, and it finally supplies (inlet connector μ) the generator 12 for reinstating the solution which is evaporated inside of the latter. The second circuit of exchangers 32, 33 is supplied starting from the solution at a high temperature which is present in the upper part of generator 12; the solution circulates then within the second circuit of these exchangers, it yields heat to the reinstatement solution of generator 12, and it finally reaches (connector v) the inner part of absorber 27.

Finally, between the outlet of the second circuit of exchanger 32 and the connector n there is a temperature-rise valve 31 which may be switched on in .the case where the condensation cycle were locked.

The invention provides for a simplified form of embodiment of the thermal-refrigerating machine, which only comprises the circuit for producing cold water.

Such form of embodiment is schematically illustrated in fig. 2.

The machine 10' according to fig. 2 is connected to a common boiler 11 for household use capable of producing hot water at a temperature comprised between 60°C and 90°C; this water circulates, by means of a pump 13', inside of a coil placed inside of a first heat exchanger/generator 12 ' , and it comes ^■ back refrigerated at a temperature comprised between ^* 55°C and 78°C to boiler 11'. The solution contained withi exchanger/generator 12 ' is of the same kind as previously described.

The vapour coming out of connector 40 of generator 12 ' is fed into a first circuit of an exchanger 14 ' acting as a condenser. The condensed fluid is then fed, through a pipe, a solenoid valve (not illustrated) and a pump 16', to the inlet of another exchanger 17' acting as refrigerator.

The fluid coming out of exchanger/refrigerator 17 ' is then fed, through a solenoid valve (not illustrated) , inside of an evaporator 19' comprising a nebulizer and a filtration unit; thereafter, the fluidi is fed back by pump 16'.

Said filtration unit 21' is of the kind as previously described; thus, it is generally constituted by a high density stainless steel mesh, suitable for allowing the passage of vapours and for holding liquids.

The upper portion of evaporator 18' communicates, by means of a large diameter pipe, with the upper portion of absorber 27 ' , in such a way as to enable the passage of vaporized solution between these elements. In steady state, the fluid has a temperature of about 5°C in correspondence of the inlet connector, and a temperature of about 12°C in correspondence of the outlet connector of exchanger/refrigerator 17 ' .

Inside of refrigerator 17 ' there is a secondo circuit in which circulates water for air conditioning use, which enters (see arrow A') the refrigerator at a temperature of about 12°C and which is available for the ^' user (see arrow B') at a temperature of about 7°C, thereby achieving the purposes of the invention.

According to this form of embodiment, the absorber 27' is constituted by an exchanger inside of which there is a coil 41 and a nebulizer 42 of the kind described above. In the coil 41 flows refrigerating water at a temperature of about 15°C coming from a fitting D' connected to the water system; the water coming from the coil at a temperature of about 43°C is then either discharged by outlet fitting C or it is used for feeding a dispersion heat exchange battery (not shown in the figures) .

The vaporized solution which is present inside of absorber 27' is condensed and fed, through a suitable connector, into a pipe which is connected to a pump 28' and, thereafter, into a first exchange circuit of an exchanger 33' . The solution coming out of said first circuit feeds then the nebulizer of generator 12'.

Inside of the second exchange circuit of exchanger 33' flows a solution coming from the lower portion of generator 12 ' ; this solution feeds the nebulizer 42 of absorber 27 ' . Figures 3 and 4 show the working diagrams of the machine according to the invention, in the respective cases where the refrigerating solution were either constituted by a lithium bromide mixture or by a hydroxydes solution.

In the case illustrated in fig. 3 (lithium bromide solution) it may be seen that the evaporation temperature is

5°C, at a pressure lower than 1000 Pa, the condensation temperature is 37°C at a pressure lower than 10000 Pa, the minimum generation temperature is 73,6°C, the generation

outlet temperature is 82°C, the maximum absortion temperature is 44,9°C and the absortion outlet temperature is 38°C.

As it may be remarked, the crystallization line of lithium bromide is rather close to the working diagram; thus, it is _. necessary to carefully check the lithium bromide rate in the solution in order to avoid any crystallization which would lead to a machine shutdown.

Such crystallization is easily avoidable by using a hydroxides mixture as described above: in fact, as it may be noted in fig. 4, the crystallization line is well spaced from the working diagram, and it is then easier to keep the system parameters under control .

The invention has been previously described with reference to an advantageous form of embodiment thereof. However, it is apparent that the invention includes several variants which fall within its terms.