MX2015001786A

MX2015001786A - Solar thermosiphon system.

Info

Publication number: MX2015001786A
Application number: MX2015001786A
Authority: MX
Inventors: Karin Lunz; Alexander Kemp; Nelly Gachignard; Uwe Clement
Original assignee: Bosch Gmbh Robert
Priority date: 2012-08-10
Filing date: 2013-08-09
Publication date: 2015-05-08
Also published as: BR112015002619A2; DE102012015984A1; EP2883008A1; AU2013301468B2; WO2014023456A1; CN104520652A; AU2013301468A1; DE102012015984B4; IN2014DN09487A; WO2014023831A1

Abstract

The invention relates to a solar thermosiphon system (1) for heating water, comprising a housing (2), in which a tank volume (3) is formed. The object of the invention is to provide a low-cost and robust thermosiphon system with high efficiency. The thermosiphon system (1) according to the invention is characterized in that in the housing (2) there is arranged a separating element (4), which separates the tank volume (3) into an absorber volume (6) and a reservoir volume (7), wherein the absorber volume (6) is arranged geodetically above the reservoir volume (7) in the operationally ready state of the thermosiphon system (1).

Description

SOLAR THERMOSYPIC SYSTEM FIELD OF THE INVENTION The invention relates to a solar thermosiphon system for heating a heat carrier fluid according to the general idea of claim 1.

BACKGROUND OF THE INVENTION A solar thermosyphon system is used to obtain heat from solar energy through a passive natural convection in a fluid circuit. A surface that absorbs solar radiation performs heat transfer on the heat carrier fluid or solar fluid, which extracts heat from the absorbent. Due to the difference in temperature and density there is a movement of the heat transfer fluid, without recirculation by a pump. Normally, as a heat carrier fluid, wastewater or potable water is used, which can be conducted directly for later use.

Thermosiphon systems, in which the volume of absorption and storage are integrated into a component, are also called integrated collector stores. Integrated collector warehouses are relatively widely spread and especially in rich countries solar radiation, serve as an economic system to heat drinking water by solar energy.

The simplest embodiment of such an integrated collector store is formed by a black container, the black outer side of which absorbs the solar radiation and transfers it in the form of heat to the heat carrier fluid inside the container. That type of integrated collector store can be produced in a very economical way. However, the heating proceeds in an uncontrolled and relatively slow manner, so that the hot water or the hot heat carrier fluid can be used only after several hours of intense radiation.

BRIEF DESCRIPTION OF THE INVENTION The invention thus proposes the task of eliminating the disadvantages of the state of the art and producing a thermosiphon system of economic production, which is assembled very easily and is correspondingly robust and presents an adequate effectiveness.

According to the invention this task is solved with the features of claim 1. Advantageous modalities are described in the dependent claims.

According to the invention, it is provided to place a separating element in the housing, such that the volume of the container is separated into an absorption volume and a storage volume, wherein the absorption volume abuts at least a part of the wall of the housing.

The housing, which in the simplest case is formed by a black closed tube, is also supplemented by a separating element, which divides the volume of the container into an absorption volume and a storage volume. In a ready-to-operate assembly, the part of the wall of the housing abutting the absorption volume is arranged in such a way that it is exposed to solar radiation. For this the housing can be placed inclined with respect to a horizontal one. Thus a temperature and density difference between the heat carrier fluid adjacent the absorbent surface in the absorption volume and the heat carrier fluid disposed in the storage volume occurs. This leads to an upward flow and a mass flow of the heat transfer fluid, whereby the heat of the absorption volume is transported. For this, the volume of absorption and the volume of storage are connected in fluid connection, for which a feeding and a feedback are provided to form a closed circuit. So it is advantageous when the The absorption volume or the separating element is directed at an angle to the horizontal, such that the hot heat carrier fluid can rise in the absorption volume and can fall in the storage volume. A vertical arrangement is also possible. The housing generally has a longitudinal, in particular cylindrical shape, in which the separating element extends in the longitudinal direction or parallel to a middle axis (longitudinal axis) of the housing. The housing can also have an inlet for introducing the heat carrier fluid and an outlet for extracting the heat carrier fluid, which is necessary in particular when heating drinking water.

In a preferred embodiment the absorption volume is much smaller than the storage volume. With this, an optimal heat transfer can be carried out in the absorption volume, and with this, strong temperature rises, whereby a sufficient storage capacity is presented in comparison with the large storage volume. Also in case of lack of solar radiation only a reduced cooling of the heat transfer fluid will be expected, since the storage volume can usually be better insulated inward than the absorption volume, and in the absorption volume it can be it clearly finds less heat transfer fluid than in the storage volume.

Preferably the part of the housing wall abutting the absorption volume is formed as a solar absorber. For example, the housing is produced with a black plastic, other materials, in particular metallic materials, are also suitable. The wall of the housing represents an absorber of the solar radiation formed in a very simple manner. In particular, a very simple, economical and simultaneously robust construction is obtained.

The storage volume and the absorption volume can be connected to each other through at least one inlet orifice and at least one outlet orifice. The exit orifice through which the heat transfer fluid flows from the absorption volume to the storage volume, in the ready-to-operate arrangement of the thermosyphon system, should be as geodesically as possible above the entry hole, through from which the heat carrier fluid comes back from the storage volume to the absorption volume. Thus a mass flow is conducted by heating in the longitudinal direction between the separating element and the side of the housing receiving the solar radiation and from there back to the storage volume, clearly indicated the direction of flow. A higher mass flow rate is advantageous for a greater degree of effectiveness and a good stratification in the storage volume.

It is especially preferred that a check valve is provided in the inlet port and / or in the outlet port. By means of the check valve it is ensured that in the case of lack of solar radiation there is no flow of fluid in the opposite direction, which would cause a cooling of the heat transfer fluid in the housing. In addition, the heat transfer fluid can only flow through the absorption volume when heat has been absorbed there.

The inlet orifice and outlet can be formed at the ends of the separator element. It is also possible for the spacer element in the longitudinal direction to be shorter than the housing, so that in the open spaces formed in the front part between the spacer element and the housing, the inlet and outlet holes are formed. In each case no connecting ducts are required between the storage volume and the absorption volume, in such a way that a very simple and robust construction is maintained. The hydraulic resistance within the thermosiphon system is also reduced, which is advantageous for a high mass flow and with this and a high degree of effectiveness.

In a preferred embodiment the spacer element extends essentially parallel to the limiting part with the absorption volume of the housing wall, where a slight spacing between the spacer element and the part of the housing wall can be provided. With this solution, the height of the spacing between the spacer element and the housing wall and also the absorption volume and the recirculated flow rate in the absorbent can be adapted under frequent or current operating and installation conditions.

Preferably in the separator element and / or in the housing, in particular on the surfaces of the separating element adjacent to the absorption volume and / or of the housing part, at least one element projecting and / or joined to the separating element and / or to the housing and / or formed in the housing is arranged. separator element and / or in the housing to predetermine the slight spacing between the spacer element and the part of the housing wall. For this, the at least one element has a predetermined height in particular. This can be treated here in the case of each thermosiphon system of one or more elements arranged around the spacer element and / or the housing, which optionally additionally have the function of a reinforcement channel, a flow and turbulence element and / or a separator. A reinforcing channel increases the rigidity of the separating element itself and reduces undesirable deformations, for example in the case of assembly or caused by the influences of heat. An element of flow and turbulence conducts and distributes the flow of the heat carrier fluid along the absorption volume. If the laminar flows are broken, then it becomes turbulent and mixes and produces a better transfer of heat from the housing to the heat carrier fluid. A separator ensures that the desired absorption volume (minimum), a flow, a temperature and / or a flow rate is maintained.

In an advantageous embodiment the element is an essentially rigid element during the operation of the thermosiphon system to determine a slight minimum separation between the spacer element and the part of the housing wall. Such a rigid element can for example be molded by an extrusion process in the flat spacer element.

Preferably the spacer element extends at least partially parallel to the part of the wall of the housing abutting the absorption volume, wherein a distance between the spacer element and part of the wall of the housing, amounts to between 2 m and 20 mm, especially between 3 mm and 10 mm, especially 4 mm. The distance between the spacer element and the wall of the housing has a high influence on the heat transfer of the wall of the housing forming the absorbent on the heat carrier fluid, which is below the absorption volume. A height of the absorption volume of 2 mm to 20 mm, in particular 4 mm represents a good compromise between high heat losses and higher temperature in the heat transfer fluid. Thus, the distance can be adjusted, for example, with the help of spacers, which can optionally be formed integrally with the spacer element and position the spacer element with reference to the wall of the housing.

In an alternative embodiment the element is an element with variable height (variable length) during the operation of the thermosyphon system to modify the slight separation between the spacer element and the part of the housing wall. It can be in particular an element, which modifies its height depending on a temperature, with this the separation is adjusted depending on the temperature. A difference in the height of the element can be performed either erratically at a predetermined temperature value, in particular at a nominal temperature or a transition temperature of the heat carrier fluid. Then a slight change in the separation is performed erratically or abruptly when a predetermined temperature occurs. Wave Variability of the element height can have a constant character and be adjusted through a range of temperatures. Then the gradual modification of the light separation is performed by the variable temperature. The type of movement drive of the variable height element can be motor, hydraulic, pneumatic, magnetic, bimetallic and / or thermal. The movement in the case of a temperature dependence can be performed by an electric motor through a temperature sensor, especially in or on the thermosyphon system, and a regulating apparatus associated with the first one. Alternatively, the movement can also be transferred to the separating element by one or more bimetallic elements, which deform under the influence of the temperature and modify their shape, length, angle or height. In another embodiment, it can start from an expansive element, for example a cylinder-piston system filled with an expansive material or a metal bellows, in which a gas, a liquid or a wax expands under the influence of temperature and modifies a Longitudinal measurement of the extended element. The bimetallic elements, the expansive element as well as the temperature sensor can be arranged in the thermosiphon system in the zone of direct or indirect influence of the heat transfer fluid.

Other dependencies of the variation of height other than the temperature dependence are also possible, for example a requirement profile dependent on the time predetermined by the user. If a user of the thermosiphon system requires hot water in the course of a short period of time, then the separation between the housing and the separator element must be reduced, for example 2 mm to 45 mm, so that along the Absorber section is adjusted a high temperature increase by flow. In any almost the magnitude of the increase in temperature coincides with greater losses of thermal radiation to the outside environment. If the user, on the other hand, requires a high efficiency of transferring solar radiation to water for a whole day, then the separation must be large, for example 4 mm to 10 mm. This reduces the increase in temperature per revolution, but at the same time heat losses by radiation to the outside are also reduced.

Most preferably, the separating element is formed as a thermal insulator. For this the separating element for example may consist of a polyethylene or polypropylene foam. But the separating element can also be formed as a hollow chamber profile. Through a conformation of the separating element as thermal insulation, a better absorption of heat is obtained during solar radiation, since the heat of the absorption volume is not transferred directly to the storage water, but first the heat carrier fluid in the absorption volume is heated. This leads to a higher available temperature in the absorption volume and thus to a higher flow through the large expansion of the heat transfer fluid caused by the temperature and finally to a better stratification of the temperature in the storage volume. When the solar radiation is missing, the separating element as a thermal insulator prevents a transfer of heat from the storage volume to the absorption volume and to the environment. Only the heat of the very small absorption volume is transferred during this time to the environment, so that in comparison with the thermosyphon systems without separating element, the heat transfer fluid after a period of time without solar radiation, for example in the morning of the next day, it has a higher temperature.

In an advantageous embodiment, the housing has a circular cylindrical shape, wherein the spacer element has a C-shaped or W-shaped cross section and is supported with its longitudinal edges on an internal wall of the housing. The separating element must present a form curve essentially around the longitudinal axis, where the longitudinal edges extend also parallel to the longitudinal axis. The shape of the separator element may have the form of the capital letter W of the Greek alphabet. The separating element can then be placed relatively easily inside the housing, which for example is formed as a tube, without requiring additional fastening elements. Eventually a press fit can be used. Frequently the friction between the longitudinal edges and the internal walls is sufficient for a secure hold of the spacer element. Especially when the spacer element extends laterally through a middle axis of the housing, a secure support of the spacer element on the inner wall of the housing can be realized with a simultaneous sealing between the absorption volume and the storage volume.

BRIEF DESCRIPTION OF THE FIGURES The drawing represents an embodiment of the invention. In which Figure 1 shows a longitudinal section through a solar thermosiphon system; Figure 2 shows a cross section through the thermosyphon system and Figure 3 shows a perspective view of a separating element.

DETAILED DESCRIPTION OF THE INVENTION In Figure 1, a solar thermal system 1 is shown in longitudinal section. The thermosyphon system 1 is formed as an integrated collector and has a closed tubular housing 2 on its front sides, in which a container volume 3 is formed. By means of a separating element 4, which is assigned to an upwardly directed portion 10 of the receiving wall 5, which serves as an absorbent, the volume of the container 3 is divided into an absorption volume 6 and a storage volume 7. The volume of absorption 6 and storage volume 7 are connected through an inlet 8 and an outlet 9.

By solar radiation, a heating of the upper geodetic housing wall 5 is performed, which functions as an absorber. The heat is transferred from the part 10 of the wall of the housing 5 to the heat transfer fluid which is in the absorption volume 5, being generally potable water. Due to the temperature and density difference of the hot heat carrier fluid that is in the absorption volume compared to the The heat carrier fluid in the storage volume 7 forms a fluid circuit, which is symbolized by arrows.

In order that the direction of flow is clearly defined, the thermosyphon system 1 is arranged in the operative position, forming an angle (for example 10 ° < angle < 90 °) with respect to the horizontal. The outlet orifice 9 is also arranged geodesically higher than the inlet orifice 8. A vertical arrangement (angle = 90 °) of the thermosyphon system is also possible.

A check valve 11 is arranged in the outlet opening 9, which for example is formed as a duckbill type valve. The check valve 11 prevents reversal of the direction of flow, for example at night, when no radiation of the sun strikes the wall of the housing 5 or on the surface of the absorbent.

The absorption volume 6 is much smaller than the storage volume 7. This results in an optimal heat transfer with reduced heat transfer losses with a high increase in the temperature of the heat transfer fluid in the absorption volume 6.

A longitudinal extension of the spacer element 4 is shorter than the longitudinal extension of the housing 2, so that the inlet hole 8 and the orifice are formed outlet 9 through a corresponding gap in the narrow sides of the separator element 3 facing the housing 2. The thermosyphon system 1 consists of very few components and correspondingly is very simple to assemble and robust.

The separating element 4 extends essentially parallel to the part 10 abutting the absorption volume 6 of the receiving wall 5 and by its flat extension in the longitudinal and peripheral direction as well as by the slight separation (height of the gap) between the element separator 4 and part 10 of the housing wall 5 form the absorption volume 6. The measurement of the slight separation corresponds to the length of the element 14 and can be predetermined. This element 14 can be an element 14 protruding and / or joined to the separating element 4 and / or a part 10 of the wall of the housing and / or which is joined or formed therein and serves to predetermine the slight separation. In figure 1 two bar-like elements 14 are shown at the lower and upper ends of the spacer element 4. No other extensions of the element 14 arranged in the longitudinal and peripheral direction of the spacer element 4 are shown. The at least one element 14 can be an invariable element during the operation of the thermosyphon system and the slight separation is set as the minimum distance between the separator element 4 and the part 10 of the wall of the housing 4. On the other hand the at least one element 144 could be a variable element 14 in height (variable in length) during the operation. With a variation of the height or length of the element 14 it is modified and the light separation is established. This also modifies and establishes the height of the flow gap and the volume size of the absorber. The actuators and sensors assigned to the element 14 and necessary for the variation of its height or length are not represented, which may be arranged inside but also outside the accommodation.

Figure 2 shows the thermosiphon system in cross section. The housing 2 has a circular cylindrical shape, that is, for example a black plastic tube. The upper half of the housing 2 represents a part 10 of the wall of the housing 5, which serves as an absorbent surface and on which the solar radiation acts which is symbolized by the arrows. This presents a heating of the housing wall 5, where the heat is transferred to the heat transfer fluid which is in the absorption volume 6. The separating element 4, which is formed with a thermal insulator, is separates the volume of the absorbent 6 from the storage volume 7, in where a fluid conducting connection is provided between the volume of the absorbent 6 of the storage volume 7 only on the narrow sides of the thermosyphon system 1, as shown in Figure 1.

The spacer element 4 has a W-shaped cross-section and abuts the longitudinal edges 12, 13 on the inner wall of the receiving wall 4. This is used to position the spacer element inside the circular cylindrical housing 2 and simultaneously a seal is formed between the absorption volume 6 and the storage volume 7, without a particularly high tightness being required.

Between the part 10 of the receiving wall 5 abutting the absorption volume and the separating element 4, at least one element 14 is provided in the form of a separator, which for example has an invariable height extension (longitudinal extension) of 4 mm and with this defines a corresponding height of the absorption volume 6. In the longitudinal and peripheral direction several separators can be found side by side or one behind the other. In addition to the function as spacers, the elements 14 can also perform the function of flow-conducting elements and / or turbulence-forming elements and turbulently turn the flow of the heat-carrying fluid through the volume of absorption for more effective heat absorption.

If the separating element 4 is used, the longitudinal edges 12, 13 and the separator (s) 14 are also slightly compressed in such a way that friction or force coupling of the separating element 4 inside the housing 2 and the separating element occurs. 4 is held within the housing 2 free of slack and jingle. Therefore additional connection elements are not necessary then.

Figure 3 shows a perspective view of a C-shaped separating element 4 with a plurality of rigid elements 14, which are placed on the flat extension of the separating element 4 in the longitudinal and peripheral direction.

The thermosiphon system according to the invention represents an integrated collector store, wherein the housing is separated into an absorption volume and a storage volume by a passive component, namely a separator element, the absorption volume is much smaller than the storage volume. In the simplest embodiment, the housing is formed as a black tube, in which a part of the housing wall that rises with the absorption volume represents a solar absorber. The principle can be used for example in a so-called tube of Vacuum glass Sydncy, in which the housing represents the inner tube of the vacuum glass tubes.

The thermosiphon system according to the invention has a very simple construction and yet a relatively high degree of effectiveness. By means of the separating element a separation is made between the volume of the absorbent and the storage volume. This achieves a stratified distribution of the heat in the storage volume and simultaneously a heating of the heat transfer fluid in the absorption volume at relatively high temperatures. This effectively heats the heat transfer fluid, so that the thermosiphon system according to the invention can be used in particular as an installation for solar heating of drinking water also in developing countries. By means of the easy construction and the small number of necessary elements, a very economical production is possible, being the thermosiphon system very robust. The thermosyphon system thus has a very low hydraulic resistance, since no additional ducts are required between the storage volume and the absorption volume, but a fluid stream can pass through holes in the separator element or through interstices on the narrow sides between the separator element and the accommodation. By means of one or more separators, the separating element can be positioned independently within the housing and possibly retained by force coupling. In total, an optimized and controlled thermal coupling is obtained by means of a defined fluid line and a temporary prior availability of the heat carrier fluid, such as hot water. This simultaneously minimizes heat losses during storage.

Claims

NOVELTY OF THE INVENTION Having described the invention as above, property is claimed as contained in the following: CLAIMS

1. A thermosyphon system (1) for heating a heat carrier fluid with a housing (2), in which a container volume (3) is formed, characterized in that a spacer element (4) is provided in the housing (2). ), in such a way that the volume of the container (3) is separated into an absorption volume (6) and a storage volume (7), wherein the absorption volume (6) abuts at least one part (10) of the housing wall (5).

2. The thermosiphon system according to claim 1, characterized in that the absorption volume (6) is much smaller than the storage volume (7).

3. The thermosiphon system according to claim 1 or 2, characterized in that the part (10) of the receiving wall (5) abutting the absorption volume is formed as a solar absorber.

4. The thermosyphon system according to one of the previous claims, characterized in that the storage volume (7) and the absorption volume (6) can be connected to each other through at least one inlet (8) and at least one outlet (9).

5. The thermosiphon system according to claim 4, characterized in that a check valve (11) is provided in the inlet (8) and / or in the outlet hole (9).

6. The thermosiphon system according to one of the preceding claims, characterized in that the separating element (4) extends essentially parallel to the limiting part with the absorption volume (6) of the receiving wall (5), being able to provide a slight separation between the separating element (4) and the part of the wall of the housing (5).

7. The thermosiphon system according to one of the preceding claims, characterized in that in the separating element (4) and / or in the housing (5), at least one element (14) is provided which projects and / or is connected to the spacer element (4) and / or the housing (5) and / or formed in the spacer element (4) and / or in the housing (5) to predetermine the slight spacing between the spacer member (4) and the spacer part (4). the wall of the housing (5).

8. The thermosiphon system according to claim 4, characterized in that the element (14) is an element (14) essentially rigid during the operation of the thermosyphon system to determine a slight minimum separation between the separator element (4) and the part of the wall of the housing (5).

9. The thermosiphon system according to one of the preceding claims, characterized in that the spacer element (4) extends at least partially parallel to the part of the wall of the housing (5) abutting the absorption volume (6), in where a distance between the spacer element (4) and part of the wall of the housing (5), amounts to between 2 mm and 20 mm, especially between 3 mm and 10 mm, especially 4 mm.

10. The thermosyphon system according to claim 7, characterized in that the element (14) is an element (14) with variable height during the operation of the thermosyphon system to modify the slight separation between the separator element (4) and the part of the housing wall (5).

11. The thermosiphon system according to one of the preceding claims, characterized in that the separating element (4) is formed as a thermal insulator.

12. The thermosyphon system according to one of the previous claims, characterized in that the housing has a circular cylindrical shape, wherein the separating element (4) has a C-shaped or W-shaped cross section and rests with its longitudinal edges (12, 13) on an internal wall ( 10).

13. The thermosiphon system according to claim 7, characterized in that the separating element (4) extends through a middle axis of the housing (2).