DE102016200197A1 - Phase Change Memory - Google Patents

Abstract

It is a phase change memory, comprising a heat exchanger (2) with at least two adjacent pipe sections (4) proposed according to the invention, the distance (40) of the adjacent pipe sections (4) along its extension between a minimum distance (41) and a maximum distance (42 ), wherein the maximum distance (42) is increased at least ten percent from the minimum distance (41). Furthermore, the invention relates to a method for freeze-desalination of a salt water in which a phase change memory according to the invention is used.

Description

The invention relates to a phase change memory, in particular a phase change memory, which is designed as an ice storage.

According to the prior art known phase change memory, in particular phase change memory, the energy store by means of a phase transition from liquid to solid or from solid to liquid, have a heat exchanger with a plurality of pipes. Typically, the tubes are flowed through by a coolant, which cools or heats a phase change material, which is provided for storing the energy through one of its phase transitions.

A known phase change memory is an ice storage, which includes water as a phase change material. The phase transition in the ice storage takes place here from water (liquid) to ice (solid) or from ice to water. The heat exchanger of an ice storage therefore allows the water to cool below its freezing point. As a result, an ice forms around the pipes of the heat exchanger.

In a typical heat exchanger, such as a shell and tube heat exchanger, the pipes extend almost parallel. Due to the growth of ice, coalescence of the ice of adjacent pipelines takes place if the thickness of the respective ice exceeds a critical radius. Here, the critical radius is typically defined by half the spacing of adjacent pipes.

The coalescence of the ice of adjacent pipelines adversely reduces the available heat transferring area of the heat exchanger, thereby degrading the efficiency and efficiency of heat transfer.

Furthermore, the growth of the ice along the pipes of the heat exchanger is not uniform, that is, the thickness of the ice along the pipes is not constant. Typically, the ice at the point of introduction of the coolant, that is at the beginning of the pipelines, has the greatest thickness, so that the ice first grows together in this area. This results in a further decrease in the effectiveness of the heat exchanger and thus of the ice storage in comparison to a uniform growth of the ice. This is the case because the thermal resistance of the ice increases with its growth. For further formation of ice, that is, for further loading of the ice storage or the phase change memory, it is therefore necessary to reduce the evaporation inlet temperature of a refrigerator, which is provided for cooling the coolant, whereby the performance of the refrigerator is also reduced.

A concept known from the prior art, which allows a more uniform growth of the ice, is the use of a heat-conducting, in particular metallic spacer between the individual pipes of the heat exchanger. In particular, between a flow and a return of the coolant, this is provided, since thereby the difference between the temperature of the flow and the temperature of the return of the coolant is reduced.

The present invention has for its object to improve the effectiveness of a phase change memory, in particular an ice storage.

The object is achieved by a phase change memory with the features of independent claim 1 and by a method having the features of independent claim 9. In the dependent claims advantageous refinements and developments of the invention are given.

The phase change memory according to the invention comprises a heat exchanger with at least two adjacent pipe sections. According to the invention, the distance of the adjacent pipe sections along their extension varies between a minimum distance and a maximum distance, the maximum distance being increased by at least ten percent in relation to the minimum distance.

It turns out that a variation of the distance of at least ten percent enables a typically sufficient improvement in the efficiency and efficiency of the phase change memory.

In the following, the invention will be described mostly using the example of an ice storage. However, the invention is not limited to an ice storage. As an ice storage a phase change memory is called, which has water as a phase change material, wherein the phase transition from water to ice or from ice to water takes place.

According to the present invention, the distance of the pipe sections of the heat exchanger varies between a minimum and a maximum distance. In other words, the pipe sections of the heat exchanger do not run as provided in the prior art, in parallel. As a result, a variable critical radius between the pipe sections is advantageously made possible, in particular in the case of ice accumulators. The critical radius is understood to be half the distance of the pipe sections at a location of the pipe sections. In a parallel course, the critical radius is substantially independent of the named location.

Furthermore, the distance between the pipe sections is defined as follows:
A fixed but arbitrary location is set on one of the pipe sections. The distance to the adjacent pipe section is then defined by the length of the shortest distance between the selected location and the adjacent pipe section. The distance of the adjacent pipe sections now varies along the pipe sections, that is, it depends on the specified location.

The fixed location of the pipe section may be located on one of its surfaces or on an axial axis of the pipe section. Furthermore, the distance, according to the above definition, to the surface of the adjacent pipe section or in turn to an axial axis of the adjacent pipe section can be determined. It is crucial that the distance over the extension of the pipe sections is defined consistently.

Due to the varying spacing of the pipe sections, the coalescence of the ice, which forms around the adjacent pipe sections, is advantageously delayed. By delaying the coalescence of the ice, the efficiency and the effectiveness of the ice storage or the phase change memory are advantageously increased. This is because, by varying the distance between the minimum and maximum distances, the efficiency of the heat exchanger is improved compared to parallel (no variation of the distance) extending pipe sections. In a parallel course of the pipe sections, as provided in the prior art, the distance between the two pipe sections along their extension, except for manufacturing inaccuracies or use-related variation, such as vibrations, constant. In other words, in this case the maximum and minimum distances over the extent of the pipe sections are substantially the same.

Typically, at least one of the pipe sections has an introduction point for a coolant, in particular a sufficiently heat-conducting fluid which flows through the pipe section. It is particularly advantageous to provide the maximum distance of the pipe sections in the region of the introduction point, that is, in the region of the flow of the coolant. This is advantageous because the ice in the region of the flow of the coolant typically grows fastest and thus has the greatest thickness in the area mentioned. Consequently, an early coalescence of the ice of the adjacent pipe sections is advantageously prevented. As a result, the effectiveness and efficiency of the phase change memory, in particular of the ice storage, can be advantageously further improved.

In the method according to the invention for the freeze-desalination of salt water, a phase change memory designed as an ice storage is used.

The above-mentioned phase change memory according to the invention results in similar and equivalent advantages of the method according to the invention. In particular, the method enables effective and efficient desalination of salt water, for example seawater.

Particularly preferably, the maximum distance is at least twenty percent, in particular fifty percent, increased compared to the minimum distance.

This advantageously further increases the effectiveness and the efficiency of the phase change memory.

According to an advantageous embodiment of the invention, the distance of the adjacent pipe sections increases substantially linearly from the minimum distance to the maximum distance.

In other words, the pipe sections extend substantially conically. As a result, an adapted to the heating of the coolant varying distance is advantageously made possible. In this case, the heating of the coolant takes place due to the cooling of the phase change material, in particular the water or ice. Advantageously, this further improves the efficiency and the effectiveness of the phase change memory.

Particularly preferably, the adjacent pipe sections are arranged substantially within a common plane.

As a result, the space available in the phase change memory space is advantageously used as efficiently as possible. Furthermore, the pipe sections can be manufactured easily manufactured. Overall, it can a heat exchanger having a plurality of levels are formed, each individual level according to the present invention having adjacent pipe sections which are arranged in said plane. This provides a particularly efficient heat exchanger.

According to a particularly preferred embodiment of the invention, the heat exchanger is designed as a spiral heat exchanger, wherein the variation of the distance of the adjacent pipe sections is formed by means of a varying between the minimum and maximum distance Windungsabstandes the spiral heat exchanger.

This advantageously provides a particularly efficient and effective phase change memory. In particular, the premature coalescence of adjacent ice layers is advantageously delayed even in the case of a heat exchanger designed as a spiral heat exchanger.

In particular, it is advantageous to couple the two pipe sections fluidly.

Here, one of the pipe sections may be provided as a flow and the other, adjacent pipe section as a return for the coolant.

Advantageously, this provides a particularly efficient phase change memory in which the flow and return of the coolant are formed by a common pipe section. The common pipe section includes the two adjacent pipe sections. For example, the common pipe section V-shaped, wherein the two legs of the symbolic letter V form the two pipe sections. This advantageously further improves the efficiency and effectiveness of the phase change memory.

According to an advantageous embodiment of the invention, at least one spacer for spacing the two pipe sections is provided between the two adjacent pipe sections.

Advantageously, this homogenizes the growth of the ice around the said pipe sections. In particular, the difference in the temperature of the coolant between its flow and return is reduced, so that the efficiency and effectiveness of the phase change memory can be further improved.

Further advantages, features and details of the invention will become apparent from the embodiments described below and with reference to the drawings. Shown schematically:

1 a detail of two pipe sections according to a first embodiment of a phase change memory according to the invention;

2 a section of a plurality of pipe sections according to a second embodiment of a phase change memory according to the invention;

3 a section of two pipe sections according to a third embodiment of a phase change memory according to the invention, wherein the pipe sections are fluidly coupled;

4 A fourth embodiment of a phase change memory according to the invention with a heat exchanger, wherein the heat exchanger is designed as a spiral heat exchanger; and

5 a diagram illustrating the increase in the effectiveness of a phase change memory according to the invention as a function of the variation of the distance between two adjacent pipe sections of the phase change memory.

Similar, equivalent or equivalent elements may be provided with the same reference numerals in the figures

In addition, the phase change memory is designed as an ice storage, that is, it comprises as a phase change material water and the phase transition occurs from water to ice or from ice to water. The coming can be easily transferred to phase change memory with other phase change materials. In this case, the phase transition of the phase change material takes place from liquid to solid or from solid to liquid.

1 shows a first embodiment of the phase change memory according to the invention. The phase change memory is designed as an ice storage and includes a heat exchanger 2 with at least two adjacent pipe sections 4 ,

The pipe sections 4 have a distance along their extent 40 on that between a minimum distance 41 and a maximum distance 42 varies, with the maximum distance 42 at least ten percent over the minimum distance 41 is enlarged.

In the illustrated embodiment, the two pipe sections extend 4 within a common level. Furthermore, the distance varies 40 the adjacent pipe sections 4 approximately linear from the minimum distance 41 to the maximum distance 42 , In other words, the two adjacent pipe sections extend 4 essentially conical within their common level. This advantageously a critical radius, characterized by the arrow 20 , continuously increases along the extension of the pipe sections from a minimum value to a maximum value. The critical radius corresponds to a maximum thickness of the ice 6 around one of the pipe sections, whereby when reaching the maximum thickness of the ice 6 the ice 6 the adjacent pipeline sections grows together.

The critical radius 20 thus limits the effectiveness and efficiency of the phase change memory. Due to the almost continuous increase in the distance 40 along the pipe sections 4 the critical radius is increased, so that the efficiency and efficiency of the phase change memory - compared to a phase change memory with parallel extending pipe sections - can be improved.

A flow direction of a coolant that the pipe sections 4 flows through, is indicated by arrows 101 characterized. Advantageously, the maximum distance 42 the pipe sections 4 provided at the point of introduction of the coolant. This is advantageous because the ice 6 begins to grow earliest at the point of introduction of the coolant. To a growing together of the ice 6 the adjacent pipe sections 4 To prevent, it is provided the maximum distance 42 to provide at the point of introduction of the coolant. The minimum distance 41 is then provided at the discharge point of the coolant.

Due to the increased effectiveness of the heat exchanger 2 is advantageously more power to cool the water to ice 6 provided. Especially when loading, that is when forming the ice 6 , this is an advantage. Thus, a faster loading of the ice storage can be achieved by a lower thermal resistance and a higher temperature of the return of the coolant. When unloading, that is melting the ice formed 6 On the other hand, the outlet temperature of the melt water produced thereby can be kept longer than a temperature of a feed line provided for use of the melt water, for example for a building air conditioning in the range of 8 degrees Celsius to 10 degrees Celsius. As a result, the phase change memory, in particular the ice storage, can be used longer even in the case of deep discharge states.

In 2 is a second embodiment of a phase change memory according to the invention with a heat exchanger 2 exemplified. The heat exchanger 2 has a plurality of adjacent pipe sections 4 on, which extend net-like and mutually conical. Furthermore, the heat exchanger has a flow 31 , also marked by the arrow 102 , as well as a return 32 , also marked by the arrow 103 , for a coolant on that the pipe sections 4 flows through. The adjacent pipe sections 4 of the heat exchanger 2 have a varying distance 40 on that between a minimum distance 41 and a maximum distance 42 varied. This is the minimum distance 41 in each case in the region of the point of introduction of the coolant. The maximum distance 42 lies in each case in the region of the discharge point of the coolant. In the illustrated second embodiment, the pipe sections 4 of the heat exchanger 2 arranged in a common plane.

For the lead 31 and the return 32 is by means of a first distributor device 11 the coolant to the majority of the pipe sections 4 fluidly distributed in parallel. Analogously, by means of a second distributor device 12 the coolant from the individual pipe sections 4 again assembled into a common flow. That from the second distributor device 12 outflowing coolant of the flow 31 (Arrow 102 ) is transferred to the first distribution device 11 of the return initiated (arrow 103 ).

3 shows a third embodiment of a phase change memory according to the invention with a heat exchanger 2 , wherein the heat exchanger 2 two pipe sections 4 has, which are fluidly coupled. The two adjacent pipe sections 4 are V-shaped or U-shaped, wherein the pipe sections form the legs of the symbolic letter V or U.

One of the pipe sections 4 is here as a lead 31 educated. The adjacent further pipeline section 4 is as a return 32 educated. This is indicated by the arrows 102 . 103 , which indicate the flow direction of the coolant, illustrates.

The illustrated embodiment has the particular advantage that an uneven coalescence of the ice 6 the adjacent pipe sections 4 additionally delayed. This is through that along the pipe sections 4 conically extending ice 6 clarified. As when loading the ice storage, the temperature of the flow 31 the coolant is lower than the temperature of its return 32 is, forms at the discharge point a thicker compared to the discharge point ice 6 out. Because the point of introduction and discharge point are approximately opposite, due to the different temperatures of the flow 31 and return 32 and due to the maximum distance in this area 42 the growing together of the ice 6 significantly delayed. This advantageously further improves the effectiveness and efficiency of the phase change memory or of the ice storage.

4 shows a fourth embodiment of a phase change memory according to the invention with a heat exchanger 2 , which is designed as a spiral heat exchanger. Here, the varying distance 40 between two adjacent pipe sections 4 of the heat exchanger 2 by means of a variation of the winding spacing 40 formed of the spiral heat exchanger. Again, it is particularly preferred at the point of introduction of a coolant - indicated by the arrow 101 - the winding distance 40 adjacent pipe sections (winding) by the maximum distance 42 given. The minimum distance 41 is located at the discharge point of the coolant, again marked by the arrow 101 , in front.

5 shows a diagram illustrating the change in the effectiveness of differently designed phase change memory as a function of the variation of the distance between two adjacent pipe sections of a heat exchanger.

The abscissa 201 of the diagram shows the state of charge of the phase change memory, in particular of the ice storage, in percent. The ordinate 202 The diagram illustrates the effectiveness of the phase change memory. Here, the numerical value 1 corresponds to the best possible effectiveness of the phase change memory.

This in 5 Diagram shown shows four curves 200 . 210 . 220 . 250 ,

The first curve 200 corresponds to a phase change memory with a heat exchanger, in which the two adjacent pipe sections are approximately parallel. The first curve 200 therefore corresponds to the state of the art.

The second curve 210 corresponds to a variation of the distance of the two adjacent pipe sections of ten percent, wherein the distance of the pipe sections increases linearly from the minimum to the maximum distance. The maximum distance is increased ten percent over the minimum distance. This clearly shows that compared to the prior art (first curve 200 ) an increased efficiency over a larger range of the state of charge of the phase change memory, can be maintained.

At the third curve 220 For example, the spacing of adjacent tubing sections varies between a minimum and a maximum distance, with the maximum distance being increased twenty percent from the minimum distance.

It can be clearly seen that the effectiveness, especially at high charge states, compared to the second curve 210 can be further improved. In other words, the bending of the respective curve takes place to lower efficiencies with increase of the percentage difference between the minimum and maximum distance with increasing charge states of the phase change memory.

This is clear from the fourth curve 250 in that the spacing of adjacent pipe sections varies between a minimum and maximum distance, the maximum distance being 50 percent greater than the minimum distance. This shows essentially no reduction in the efficiency of the phase change memory up to high charge states of at least 90 percent and approximately 100 percent. In other words, by varying the distance of the adjacent pipe sections, in particular by a variation, the curve 250 is true, the effectiveness over the entire state of charge from 0 to at least 90 percent upright and kept approximately constant. By the present invention, thus, the effectiveness of the phase change memory over the prior art, the first curve 200 corresponds, significantly improved.

Although the invention has been further illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples, or other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims (10)

Phase change memory, comprising a heat exchanger ( 2 ) with at least two adjacent pipe sections ( 4 ), characterized in that the distance ( 40 ) of the neighboring ones Pipe sections ( 4 ) along its extent between a minimum distance ( 41 ) and a maximum distance ( 42 ), the maximum distance ( 42 ) at least ten percent over the minimum distance ( 41 ) is enlarged. Phase change memory according to claim 1, characterized in that the maximum distance ( 42 ) at least twenty percent, in particular fifty percent, with respect to the minimum distance ( 41 ) is enlarged. Phase change memory according to claim 1 or 2, characterized in that the distance ( 40 ) of the adjacent pipeline sections ( 4 ) substantially linearly from the minimum distance ( 41 ) to the maximum distance ( 42 ). Phase change memory according to one of the preceding claims, characterized in that the adjacent pipe sections ( 4 ) are arranged substantially within a common plane. Phase change memory according to one of claims 1 to 3, characterized in that the heat exchanger ( 2 ) is designed as a spiral heat exchanger, wherein the variation of the distance ( 40 ) of the adjacent pipeline sections ( 4 ) by means of a between the minimum and maximum distance ( 41 . 42 ) varying winding distance ( 43 ) of the spiral heat exchanger is formed. Phase change memory according to one of the preceding claims, characterized in that the two pipe sections ( 4 ) are fluidically coupled. Phase change memory according to one of the preceding claims, characterized in that the pipe sections ( 4 ) can be flowed through by a coolant, wherein one of the two pipe sections ( 4 ) as lead ( 31 ) and the other as return ( 32 ) is provided for the coolant. Phase change memory according to one of the preceding claims, characterized in that between the two pipe sections ( 4 ) at least one spacer for spacing the two pipe sections ( 4 ) is provided. Phase change memory according to one of the preceding claims, characterized in that the heat exchanger ( 2 ) is disposed within an ice storage, wherein the heat exchanger for freezing a water, in particular a salt water, is provided. Process for the freeze-desalination of a salt water, in which a phase change memory designed as an ice storage ( 2 ) is used according to one of the preceding claims.

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