Absorption-cycle refrigerating unit

Abstract

An absorption-cycle refrigerating unit, comprising an electrically heated boiler, covered with a layer of mineral wool that is covered by an external enclosure made of expanded plastic material.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an improvement to an absorption-cycle refrigerating unit.

[0002] As is known, in absorption-cycle refrigerating units the refrigeration fluid is generally constituted by a mixture of water and ammonia that is heated in a boiler by way of the heat provided by an electrical resistor. The generated heat causes the evaporation of the ammonia, which separates from the water. As evaporation proceeds, the pressure increases until it is high enough to cause the condensation of the ammonia. According to what occurs in compression-cycle refrigerating units, the ammonia, through a valve, then expands in an evaporator, returning to the gaseous state and drawing heat from the surrounding environment (the inside of a refrigerator). The water, which now contains small quantities of ammonia, passes from the boiler into the absorber, through a heat exchanger, to which it transfers part of its heat. Here it mixes with the pure ammonia vapor that arrives from the evaporator and becomes saturated. A circulation pump returns the mixture of ammonia and water to the boiler through the heat exchanger, where the mixture absorbs the heat of the water that arrives from the boiler. The cycle can therefore resume in the described manner.

[0003] As is evident, in order to maintain a high efficiency of absorption-cycle refrigerating units it is crucial to limit the heat losses of the boiler and increase its efficiency.

SUMMARY OF THE INVENTION

[0004] The aim of the present invention is therefore to improve an absorption-cycle refrigerating unit that allows to achieve a higher inflow of calories to the boiler and therefore reduce the time required by the unit to reach the intended operating temperature, with corresponding triggering of the power-off device, or allows to use a less powerful electric resistor.

[0005] Within this aim, an object of the present invention is to provide an assembly in which the improvements that have been introduced have no appreciable effect on the cost standpoint of the unit.

[0006] This aim and this object are achieved according to the present invention with an absorption-cycle refrigerating unit, comprising an electrically heated boiler, characterized in that said boiler is covered with a layer of mineral wool that is covered by an external enclosure made of expanded plastic material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Further features and advantages of the present invention will become better apparent from the description that follows of a preferred embodiment, illustrated only by way of non-limitative example in the accompanying drawings, wherein:

[0008] FIG. 1 is a perspective view of an absorption-cycle refrigerating unit;

[0009] FIG. 2 is a front elevation view of the unit of FIG. 1 with the boiler shown in cross-section;

[0010] FIG. 3 is a sectional view, taken along the line III-III of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] With reference to the figures, the reference numeral 1 generally designates an absorption-cycle refrigerating unit. Unit 1 comprises, as described initially, a boiler 2, whose output is connected to a condenser 3. The output of the condenser 3, through an expansion valve or choke (not shown), is connected to an evaporator 4, whose output is in turn connected to an absorber 5.

[0012] The reference numeral 6 designates a tank for collecting the refrigeration mixture, in which the input is connected to the output of the absorber 5 and the delivery is connected to the input of the boiler 2. The circuit contains a gas (helium) under pressure, which allows to control the cycle of the refrigeration fluid.

[0013] The boiler 2, the condenser 3, the absorber 5 and the tank 6 are mounted externally with respect to the space to be refrigerated (refrigeration cell) and in which the evaporator 4 is located.

[0014] In the continuation of the description, the connections among the various components are not described, since they are fully conventional and unrelated to the present invention, whose particularities reside in the structure of the boiler.

[0015] As clearly shown in FIGS. 1 to 3, the boiler 2 is constituted by a tubular element or sleeve 7 that lies vertically between the tank 6 and the condenser 3. A heating body is fixed thereon and is constituted by an electrical resistor 8 that is powered by means of conductors 9. Advantageously, the electrical resistor 8 has a semicylindrical shape that allows to surround a large region of the tubular element 7. This provides a wide surface of contact between the tubular element 7 and the resistor 8, which ensures greater heat exchange while containing the diametrical dimensions of the heating element and therefore the space occupation.

[0016] A layer 10 of thermally insulating material, for example made of mineral wall such as rock wool or glass wool, is arranged around the electrical resistor 8 and, if appropriate, around the tubular element 7.

[0017] Conveniently, the tubular element 7 is covered along its entire length by an additional layer of thermally insulating material, which consists of an enclosure 11 made of expanded plastic material. Preferably, said material is an expanded polyurethane, which is capable of providing an effective barrier against the irradiation of heat and therefore constitute an effective thermal protection for the nearby components.

[0018] It should be noted that the thermally insulating layer 10 of mineral wool also ensures an effective protection for the polyurethane enclosure 11, protecting it against excessive temperatures at the electric resistor 8.

[0019] It is evident that the described improvement allows to achieve the intended aim and object. In particular, the arrangement of the layer 10 and of the enclosure 11 has allowed to reduce significantly the consumption of electric power. According to tests that have been conducted, the energy saving can be quantified as on the order of 20% with respect to the consumption of refrigerating units currently in use.

[0020] The described refrigerating unit 1 is susceptible of numerous modifications and variations, all of which are within the scope of the same solution idea. In a preferred embodiment, the enclosure 11 made of expanded plastic material is prism-shaped, with a quadrangular cross-section that allows to better utilize the space around the tubular element 7.

[0021] In another embodiment, the boiler 2 is accommodated in a metallic box-like body for containing the enclosure 11 made of plastic material.

[0022] In the practical execution of the invention, the shapes and the dimensions may be any according to requirements.

[0023] The disclosures in Italian Patent Application No. BO2001A000613 from which this application claims priority are incorporated herein by reference.

Claims

1. An absorption-cycle refrigerating unit, comprising: an electrically heated boiler, a layer of mineral wool that covers said boiler; and an external enclosure made of expanded plastic material which covers said layer of mineral wool.

2. The refrigerating unit of claim 1, wherein said external enclosure is made of expanded polyurethane.

3. The refrigerating unit of claim 1, wherein said boiler is constituted by a tubular element, a heating body fixed on said tubular element, said heating body being constituted by an electric resistor that has a semicylindrical shape and is provided so as to surround a region of said heating body.

4. The refrigerating unit of claim 2, wherein said enclosure made of expanded plastic material has a prism-like quadrangular cross-section.

5. The refrigerating unit of claim 4, further comprising a metallic box-like body which contains said enclosure made of expanded plastic material.