Absorber for a chiller for motor vehicles, and chiller comprising the absorber

Abstract

An absorber (20) for a chiller (90) for motor vehicles (100), comprising a heat exchange chamber (31). The heat exchange chamber is configured to provide an absorption of vapor (18) by a weak solution (14) in the liquid state, by way of a heat transfer / cooling fluid (12). The heat exchange chamber (31) comprises a plurality of plates (60) which is configured to provide a counterflow heat exchange between at least one hot current and at least one cooling current. Each hot current is formed by the vapor (18) and by the weak solution (14). Each cooling current is formed by the heat transfer / cooling fluid (12).

Description

[0001] The present invention relates to an absorber for a chiller for motor vehicles. Furthermore, the invention relates to a chiller for motor vehicles that comprises such an absorber.

[0002] In particular, the chiller referred to is an absorption machine, i.e. a machine in which the operation is based on an absorption refrigerating and / or refrigerant cycle.

[0003] The absorber and the chiller according to the invention are particularly useful and practical for applications on board vehicles such as trucks, camper vans and the like.

[0004] As is known, every absorption machine is made up of several components. Of all these components, the absorber is what has the greatest impact on the performance and encumbrance of the respective machine. It follows from this that, in every absorption machine, the type of absorber and the accuracy of the dimensioning of that absorber are two crucial aspects.

[0005] As is likewise known, developing a chiller for applications on board vehicles is constrained by limitations on bulk that are quite stringent. In fact, in order to be able to install an absorption machine on a motor vehicle, it must be possible for the absorber to be accommodated under a floor of the motor vehicle. Typically, an absorber for motor vehicles therefore must have a maximum vertical space occupation limited to 300-400 mm, and a maximum total volume comprised between 100 and 200 liters. Furthermore, since the installation is for a moving vehicle, the total mass of the absorber must not exceed 50-100 kg, so as not to excessively penalize the dynamic performance of the motor vehicle.

[0006] The state of the art comprises several types of absorber, each with advantages and drawbacks in terms of efficiency and compactness of the associated absorption machine.

[0007] One known type of absorber is the "film absorber", i.e. an absorber in which operation is based on the absorption of vapor by a "weak solution". Typically, the "weak solution" is a coolant liquid (for example ammonia), diluted with a solvent (for example water).

[0008] Basically, when the film absorber is in operation, the weak solution moving around inside a heat exchange chamber of the absorber generates a liquid film that absorbs the vapor, so giving rise to a "film absorption".

[0009] Among the known absorption chillers that are currently industrially manufactured, the most common have a shell-and-tube film absorber, i.e. a film absorber that comprises a bundle of absorption tubes. Typically, the bundle of absorption tubes is a bundle of horizontal tubes (like the one in Figure 1, indicated by the reference numeral 22), or a bundle of superimposed tubular coils. When the bundle of absorption tubes is arranged horizontally, the shell-and-tube film absorber is called a "horizontal shell-and-tube film absorber".

[0010] In conventional shell-and-tube film absorbers, the bundle of absorption tubes is passed through internally by a heat transfer / cooling fluid, and the weak solution is sprayed over it.

[0011] Basically, when a shell-and-tube film absorber is in operation, the weak solution is supplied to the bundle of absorption tubes by a distributor of the weak solution (in Figure 1: reference numeral 24). During the percolation, the weak solution absorbs vapor. The absorption - or rather, "film absorption" - process occurs at each interface between the vapor and the liquid film generated by the weak solution sprayed over the tubes (or coils) of the bundle of absorption tubes. The heat released by the absorption process is removed by the heat transfer / cooling fluid.

[0012] Although commercially very successful, the shell-and-tube film absorber presents some drawbacks, including the fact that it is rather cumbersome. Another disadvantage lies in the fact that it is not very efficient: typically, a shell-and-tube film absorber has a thermal approach (defined as the difference between the outflow temperature of the weak solution and the inflow temperature of the heat transfer / cooling fluid) of approximately 5-6°C. Furthermore, a shell-and-tube film absorber requires careful design of the distributor of the weak solution, in order to ensure the correct spraying of the tube bundle.

[0013] The aim of the present invention is to overcome the limitations of the known art described above, by devising an absorber and a chiller that offer high practicality, versatility, and efficiency.

[0014] Within this aim, an object of the present invention is to provide an absorber that enables a reduction in space occupation over those used by known chillers for motor vehicles.

[0015] Another object of the present invention is to reduce the total mass of conventional absorbers and / or of chillers for motor vehicles that comprise these conventional absorbers.

[0016] Another object of the present invention is to reduce the thermal approach of conventional absorbers for chillers for motor vehicles.

[0017] An additional object of the present invention is to increase a coefficient of performance (hereinafter: COP) of a chiller for motor vehicles.

[0018] Another object of the present invention is to provide an absorber and a chiller that are highly reliable, easily and practically implemented, and economically competitive when compared to the known art.

[0019] This aim and these and other objects which will become more apparent hereinafter are achieved by an absorber according to claim 1. The aim and one or more of the set objects are likewise achieved by the dependent claims.

[0020] Further characteristics and advantages of the present invention will become better apparent from the description of a preferred, but not exclusive, embodiment of the absorber and of the chiller according to the invention, illustrated by way of non-limiting example with the aid of the accompanying drawings wherein: Figure 1 shows the main sections of a traditional horizontal shell-and-tube film absorber according to the prior art; Figure 2 is a cross-sectional view of an absorber according to the invention; Figure 3 is a schematic diagram (based on Figure 2) adapted to show a plurality of flows that pass through the absorber of Figure 2 when that absorber is in operation; Figure 4 is a side view of part of a chiller and of a motor vehicle intended to accommodate that chiller, the chiller comprising an absorber according to the invention.

[0021] In the figures, the reference numeral 30 designates an absorber according to the present invention.

[0022] In particular, the absorber 30 is a film absorber.

[0023] In some embodiments, the absorber 30 constitutes a self-contained unit. In other embodiments, the absorber 30 is integrated in a chiller 90 such as, for example, an absorption chiller.

[0024] In the preferred and illustrated embodiments, the absorber 30 and the chiller 90 are adapted to be installed on board a motor vehicle 100.

[0025] In each embodiment, the absorber 30 comprises a heat exchange chamber 31.

[0026] The heat exchange chamber 31 is configured to provide an absorption of vapor 18 by a weak solution 14 in the liquid state, by way of a heat transfer / cooling fluid 12.

[0027] Preferably, the vapor 18 is ammonia vapor.

[0028] In particular, when the absorber 30 is installed in the chiller 90, the vapor 18 is supplied by an evaporator (not shown) which forms part of the chiller 90. By contrast, the weak solution 14 is provided by a generator (not shown) which also forms part of the chiller 90.

[0029] Basically, the absorber 30 can be defined as a (vapor) absorption device.

[0030] In some preferred embodiments, an internal volume of the heat exchange chamber 31 is comprised between 1 and 1.5 liters.

[0031] Basically, the internal volume of the heat exchange chamber 31 defines the internal volume V int of the absorber 30.

[0032] In each embodiment, the heat exchange chamber 31 comprises a plurality of plates 60.

[0033] Preferably, the plurality of plates 60 is made of steel (for example, AISI 316L).

[0034] In some variants, the plurality of plates 60 is formed by a total number of plates N 60 equal to 50. However, there are also alternative variants, wherein the total number of plates N 60 is greater than or less than 50. For example, in these alternative variants, the total number of plates N 60 can be comprised between 45 and 55, or between 40 and 60.

[0035] Preferably, each plate of the plurality of plates 60 has a height L 60 of approximately 30 cm and a width W 60 of approximately 7 cm. In this manner, it is possible to limit the overall weight of the absorber 30. For example, when the total number of plates falls within the intervals mentioned above, a total mass M tot of the absorber 30 can vary between 4 and 5 kg (according to the total number of plates and / or the material used).

[0036] Advantageously, the plurality of plates 60 is designed to provide a counterflow heat exchange between at least one hot current (i.e., one or more hot currents) and at least one cooling current (i.e., one or more cooling currents). Each hot current is formed by the vapor 18 and by the weak solution 14. By contrast, each cold current is formed by the heat transfer / cooling fluid 12. In this manner, an absorber 30 is obtained which is extremely compact and effective. For example, when the absorber 30 has a total (external) volume V tot between 3 and 4 liters, the thermal approach of that absorber 30 can be comprised between 2 and 3°C.

[0037] Basically, when the absorber 30 is in operation, the vapor 18 and the weak solution 14 move inside the heat exchange chamber 31, along a first movement direction. At the same time, the heat exchange chamber 31 is passed through by the heat transfer / cooling fluid 12, which moves along a second movement direction, opposite to the first movement direction. In this manner, a counterflow heat exchange is obtained between two or more flows that move along opposite movement directions. The result is that the absorber 30 acts like a counterflow heat exchanger.

[0038] In Figure 3, any arrow 16 can represent the first movement direction, while any arrow 17 can represent the second movement direction.

[0039] In optimal embodiments, the absorber 30 is a brazed plate heat exchanger.

[0040] The use of a brazed plate heat exchanger gives the absorber 30 greater compactness, versatility and efficiency.

[0041] In the preferred and illustrated embodiments, the absorber 30 comprises a first access region 32, a second access region 34, and a plurality of channels 36.

[0042] The first access region 32 is adapted to feed the heat exchange chamber 31 with the vapor 18 and the weak solution 14.

[0043] Basically, the first access region 32 makes it possible to introduce the vapor 18 and the weak solution 14 into the absorber 30.

[0044] In particular, when the absorber 30 is installed in the chiller 90, the absorber 30 is in a position to receive the vapor 18 and the weak solution 14 from a distributor 70 (via the first access region 32).

[0045] Basically, the distributor 70 is arranged upstream of the absorber 30.

[0046] In the preferred and illustrated embodiments, the distributor 70 is three-way (i.e., it comprises a T-junction).

[0047] In particular, the distributor 70 comprises: a first route 72, which can be fed with the weak solution 14; a second route 74, which can be fed with the vapor 18; and a third route 76, to allow the weak solution 14 and the vapor 18 to exit the distributor 70.

[0048] Preferably, the third route 76 ends in an outlet which is adapted to engage with a respective inlet of the first access region 32 (for example, as shown in Figure 4).

[0049] Basically, when the chiller 90 is in operation, the third route 76 allows the weak solution 14 (which enters the distributor 70 via the first route 72) and the vapor 18 (which enters the distributor 70 via the second route 74) to flow downstream of the distributor 70 (i.e., in Figure 4: in the absorber 30, via the first access region 32).

[0050] Preferably, the first access region 32 is defined in an upper portion 30U of the absorber 30.

[0051] In some preferred embodiments, the first access region 32 comprises a first access port 31, which is adapted to introduce the weak solution 14 into the absorber 30, and a second access port 33, which is adapted to introduce the vapor 18 into the absorber 30.

[0052] Preferably, the first access port 31 is defined by a first pipe 35, while the second access port 33 is defined by a second pipe 38.

[0053] In some preferred embodiments, the first and the second pipe 35, 38 are arranged one inside the other.

[0054] In the preferred and illustrated embodiments, the first pipe 35 is arranged inside the second pipe 38.

[0055] Preferably, the first pipe 35 and the second pipe 38 are coaxial.

[0056] In some preferred embodiments, the first pipe 35 has an outside diameter OD 35 comprised between 8 and 10 mm, while the second pipe 38 has an outside diameter OD 38 comprised between 8 and 10 mm.

[0057] In the preferred and illustrated embodiments, the first access port 31 and the second access port 33 are mutually spaced apart along a longitudinal direction. However, alternative embodiments (not shown) are also possible, in which the first access port 31 and the second access port 33 are located at a same longitudinal position along an axis of the first pipe 35 and / or of the second pipe 38.

[0058] The second access region 34 is adapted to feed the heat exchange chamber 30 with the heat transfer / cooling fluid 12.

[0059] Basically, the second access region 34 makes it possible to introduce the heat transfer / cooling fluid 12 into the absorber 30.

[0060] Preferably, the second access region 34 is defined in a lower portion 30L of the absorber 30.

[0061] Preferably, the plurality of channels 36 extends from the upper portion 30U to the lower portion 30L of the absorber 30.

[0062] In particular, the plurality of channels 36 extends through the heat exchange chamber 31.

[0063] Each channel 36 is (at least partially) defined by a respective pair of plates that belong to the plurality of plates 60. For example, in Figure 2: a first channel 36A is defined by a first pair of plates 60A, 60B; a second channel 36B is defined by a second pair of plates 60C, 60D; and a third channel 36C is defined by a third pair of plates 60E, 60F.

[0064] The plurality of channels 36 is collectively adapted to interface the vapor 18 with the weak solution 14. In other words, the plurality of channels 36 is adapted to generate a plurality of liquid-vapor interfaces 11 inside the heat exchange chamber 31. Furthermore, the plurality of channels 36 is collectively adapted to cool each interface 11 between the vapor 18 and the weak solution 14, by way of the heat transfer / cooling fluid 12.

[0065] In the preferred and illustrated embodiments, the plurality of channels 36 extends through the heat exchange chamber 31, from the upper portion 30U to the lower portion 30L.

[0066] Basically, the vapor 18 and the weak solution 14 that enter the heat exchange chamber 31 flow from the upper portion 30U to the lower portion 30L (i.e., in Figures 2-4, downward from above), proceeding along the first movement direction. At the same time, the heat transfer / cooling fluid 12 that enters the heat exchange chamber 31 proceeds along the second movement direction, moving from the lower portion 30L to the upper portion 30U (i.e., in Figures 2-4, upward from below). In proceeding along the plates 60, the weak mixture 14 forms the liquid film, which absorbs the vapor 18, and the heat released by the absorption of the vapor 18 is removed by the heat transfer / cooling fluid 12.

[0067] In practice it has been found that each absorber and / or each chiller according to the present invention fully achieves the set aim and objects, in that they make it possible to overcome the qualitative limitations of the known art explained above.

[0068] In particular, the absorber (and, therefore, the chiller) according to the present invention makes it possible to obtain the following advantages: reduction by an order of magnitude (10 times) of space occupation with respect to traditional devices; reduction by an order of magnitude (8-10 times) of the total mass with respect to traditional devices; reduction by an order of magnitude (20-30 times) of the internal volume (and, therefore, of a charge of refrigerant mixture) with respect to traditional devices; reduction by 50% of the thermal approach with respect to traditional devices, with an increase of 5-10% in the COP of the chiller.

[0069] By way of example, a comparison between an absorber according to an optimal embodiment of the invention (hereinafter, for brevity: "optimal absorber") and a traditional horizontal shell-and-tube film absorber (hereinafter, for brevity: "traditional absorber", designated by the reference numeral 20 of Figure 1) produces the results given in the following table: Traditional absorberOptimal absorberStructureBundle of aligned horizontal pipes in stainless steel (AISI 316L), with:Brazed plate heat exchanger in AISI 316L, with:- outside diameter, OD 26 , of each pipe 26: 12.7 mm;- L 60 : 300 mm;- length of pipes, L 26 : 500 mm;- W 60 : 75 mm;- pitch between pipes, P 26 : 17.5 mm;- N 60 : 50.- total number of pipes, N 26 : 48;- bundle diameter, ϕ: 300-330 mm.V tot 35 - 40 13 - 4 lV int 30 - 3511 - 1.5 lM tot 30-40 kg4-5 kgThermal approach5-6°C2-3°C

[0070] From the above table it can be seen that the optimal absorber according to the invention is approximately 10 times less cumbersome and 8 times lighter than the traditional absorber. The optimal absorber also has an internal volume 20-30 times smaller than that of the traditional absorber, so allowing a proportional reduction of the charge of refrigerant mixture. Furthermore, the optimal absorber ensures a thermal approach that is approximately half of that of the traditional absorber, with considerable beneficial effects on the thermodynamic efficiency of the chiller. These beneficial effects can be quantified as a 5-10% increase in COP.

[0071] Although the absorber and the chiller according to the invention have been conceived in particular for motor vehicles such as trucks, camper vans and the like, they can also be used, more generally, for other types of vehicles.

[0072] The invention, thus conceived, is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

[0073] Except where indicated otherwise, the various embodiments described above can be combined in order to provide further and / or alternative embodiments.

[0074] Moreover, all the details may be substituted by other, technically equivalent elements.

[0075] In practice the materials employed, provided they are compatible with the specific use, and the contingent dimensions and shapes, may be any according to requirements and to the state of the art.

[0076] In conclusion, the scope of protection of the claims shall not be limited by the explanations or by the preferred embodiments illustrated in the description by way of examples, but rather the claims shall comprise all the patentable characteristics of novelty that reside in the present invention, including all the characteristics that would be considered as equivalent by the person skilled in the art.

[0077] Where the technical features mentioned in any claim are followed by reference numerals and / or signs, those reference numerals and / or signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference numerals and / or signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference numerals and / or signs.

Claims

1. An absorber (30) for a chiller (90) for motor vehicles (100), said absorber (30) comprising a heat exchange chamber (31), said heat exchange chamber (31) being configured to provide an absorption of vapor (18) by a weak solution (14) in the liquid state, by way of a heat transfer / cooling fluid (12); characterized in that said heat exchange chamber (31) comprises a plurality of plates (60) which is configured to provide a counterflow heat exchange between at least one hot current and at least one cooling current, each hot current being formed by said vapor (18) and said weak solution (14), and each cooling current being formed by said heat transfer / cooling fluid (12).

2. The absorber (30) according to claim 1, characterized in that said absorber (30) is a film absorber.

3. The absorber (30) according to claim 1 or 2, characterized in that said absorber (30) is a brazed plate heat exchanger.

4. The absorber (30) according to any one of the preceding claims, characterized in that it further comprises: a first access region (32), adapted to feed said heat exchange chamber (31) with said vapor (18) and said weak solution (14); a second access region (34), adapted to feed said heat exchange chamber (30) with said heat transfer / cooling fluid (12); and a plurality of channels (36), each channel (36A; 36B; 36C) of said plurality of channels (36) being defined at least partially by a respective pair of plates (60A-B; 60C-D; 60E-F) that belong to said plurality of plates (60), said plurality of channels (50) being collectively configured to: - interface said vapor (18) with said weak solution (14), and - cool each interface (11) between said vapor (18) and said weak solution (14), by way of said heat transfer / cooling fluid (12).

5. The absorber (30) according to claim 4, characterized in that: said first access region (34) is defined in an upper portion (30U) of said absorber (30); and said second access region (34) is defined in a lower portion (30L) of said absorber (30).

6. The absorber (30) according to claims 4 and 5, characterized in that said plurality of channels (36) extends through said heat exchange chamber (31), from said upper portion (30U) to said lower portion (30L).

7. The absorber (30) according to any one of the preceding claims, characterized in that : - an internal volume of said heat exchange chamber (31) is comprised between 1 and 1.5 liters; - a total number of plates of said plurality of plates (60) is comprised between 40 and 60, preferably between 45 and 55, more preferably equal to 50; - a total volume of said absorber (30) is comprised between 3 and 4 liters; and said absorber (30) has a thermal approach comprised between 2 and 3°C.

8. The absorber (30) according to any one of the preceding claims, characterized in that : each plate (60, 60B, 60C) of said plurality of plates (60) is approximately 30 cm high and approximately 7 cm wide; and a total mass of said absorber (30) is comprised between 4 and 5 kg.

9. A chiller (90) for motor vehicles (100), characterized in that it comprises an absorber (30) according to any one of the preceding claims.

10. The chiller (90) according to claim 9, characterized in that it further comprises a distributor (70), said absorber (30) being configured to receive said vapor (18) and said weak solution (14) from said distributor (70).

11. The chiller (90) according to claim 10, characterized in that said distributor (70) is a three-way distributor.

12. A motor vehicle (100) comprising an absorber (30) according to any one of claims 1 to 8 or a chiller (90) according to any one of claims 9 to 11.

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