Device for heat recovery and recirculation, and its use

Abstract

The invention relates to a device for heat recovery from waste heat-conducting devices and for returning the recovered heat, comprising at least: at least one heat storage channel arranged around a waste heat-conducting device; and at least one ventilation channel, wherein the at least one heat storage channel is arranged inside the ventilation channel and the ventilation channel has at least one inlet and at least one outlet, wherein at least one heat storage medium is arranged in the heat storage channel and the heat storage medium is selected from latent heat storage materials, thermochemical and sensible heat storage materials.

Description

[0001] The invention relates to a device for heat recovery and recirculation, as well as its use.

[0002] Combustion systems require a continuous supply and removal of air to maintain the oxidative reaction, as well as of hot flue gases. These flue gases can be toxic. However, the removal of hot flue gases also carries away large amounts of heat energy through the exhaust system, the chimney. Older systems, in particular, have a significantly lower efficiency, so large amounts of heat energy are lost through the exhaust system.

[0003] Technical systems for heat recovery already exist in industrial exhaust gas systems, but not in the area of ​​smaller residential buildings (single-family houses (EFH), smaller multi-family houses (MFH)).

[0004] CN 212 746 533 U discloses a chimney and a flue gas heat recovery system. The chimney has a chimney body consisting of an inner and an outer layer, forming a double-layer structure with a cavity between them. A phase-change material is arranged within the cavity. Within the phase-change material, a tube is arranged spirally around the inner layer of the chimney, in which a heat exchange medium circulates. A disadvantage of this system is that it is unsuitable for high flue gas temperatures of up to 300°C.

[0005] EP 3 467 419 A1 discloses a combi boiler for waste heat recovery. The combi boiler has at least one water supply line and a flue through which exhaust gases flow. The flue comprises a heat storage element with at least one phase-change material, which is arranged next to the flue duct. The water supply line comprises a preheating line, which is arranged next to the heat storage element, so that heat is transferred from the heat storage element to the preheating line. Another disadvantage is that such a combi boiler is not suitable for high exhaust gas temperatures up to 300°C.

[0006] WO 18 00760 A1 discloses a heat exchanger for heat recovery from exhaust systems. The heat exchanger is made of two layers of sheet metal wound into a spiral and connected only by welding. Such a heat exchanger can be placed, for example, at the top of a chimney.

[0007] WO 2004 / 046632 A1 describes a storage heat exchanger for heating systems. The storage heat exchanger comprises several containers filled with latent heat storage media and arranged within a fluid-containing container. The heat is transferred to an air supply layer via the container walls.

[0008] EP 1 562 000 A1 discloses a method for utilizing the exhaust heat of a heat generator to heat a building. A flue pipe, which is part of a combustion system, is used and operated as a water-exhaust heat exchanger. The transfer of sensible heat and condensation heat of the flue gas to the cooling water inside the flue pipe occurs through direct contact of the cooling water with the flue gas and, in part, with the inner pipe wall.

[0009] The task is therefore to provide a device for heat recovery and heat recirculation for small residential buildings and exhaust gas temperatures up to 300°C, which overcomes the disadvantages of the state of the art.

[0010] According to the invention, this object is achieved by a device according to the independent claims. The object is further achieved by the use of the device according to claims 10 and 11. Advantageous embodiments of the invention are specified in the dependent claims.

[0011] A first aspect of the invention relates to a device for heat recovery from waste heat conducting devices and for returning the recovered heat, comprising at least: • at least one heat storage channel arranged around a waste heat conducting device, • and at least one ventilation duct, wherein the ventilation duct has at least one inlet and at least one outlet, wherein at least one heat storage medium is arranged in the heat storage duct and the heat storage medium is selected from latent heat storage materials, thermochemical and sensible heat storage materials.

[0012] Such a device advantageously enables the recovery of heat and its return to the building envelope for further use. Furthermore, the device according to the invention advantageously enables the recovery of heat and its return to any waste heat-conducting devices, e.g., exhaust air ducts, sewage pipes, or other process-related fluid lines. Furthermore, such a device can be used both in new buildings and retrofitted to existing buildings. Furthermore, the device according to the invention advantageously enables the use of air as a heat transfer medium for heating buildings.

[0013] Waste heat-conducting devices within the meaning of the invention refer to any fluid-conducting devices in buildings, such as pipes, where the conducting fluids can be gaseous or liquid. Examples of waste heat-conducting devices include exhaust air ducts, exhaust gas ducts, e.g., from combustion plants, sewage ducts, or ducts that carry process fluids. In embodiments, the waste heat-conducting devices are designed as pipes, where the pipes are designed to be heat-conducting, e.g., stainless steel pipes. Pipes or tubular devices refer to devices or lines with a round or polygonal cross-section, where the cross-section is a plane perpendicular to the length of the pipe or device, where the length represents the longest dimension of the pipe or device.Pipelines or tubular devices can run in a straight line or be curved in sections, depending on the specific installation conditions of the building in which they run.

[0014] A heat storage channel within the meaning of the invention refers to a channel surrounding the waste heat-conducting device, which contains at least one heat storage medium. The at least one heat storage channel can surround the waste heat-conducting device in such a way that the waste heat-conducting device and the heat storage channel are in direct contact with each other or are arranged in spatial proximity to each other.

[0015] In some embodiments, the heat storage channel is tubular. In other embodiments, the heat storage channel is formed entirely from the at least one heat storage medium. In other embodiments, the at least one heat storage medium is arranged within the heat storage channel, and the heat storage channel is delimited to the outside by a heat-conducting wall. A heat-conducting wall can, for example, be a metallic tube. In other embodiments, the heat storage channel completely surrounds the waste heat-conducting device over the entire length of the waste heat-conducting device. In some embodiments, the heat storage channel almost completely surrounds the waste heat-conducting device over the entire length of the waste heat-conducting device.Almost complete means at least 50%, preferably at least 70%, particularly preferably at least 90% of the length of the waste heat conducting device. The length of the waste heat conducting device means the extent of the waste heat conducting device starting at the point where the waste heat is generated and ending at the point where the waste heat escapes into the environment. In the case of an exhaust pipe of a combustion plant, the point where the waste heat is generated is, for example, the connection of the exhaust pipe to the combustion plant and the point where the waste heat escapes into the environment is, for example, the end of the chimney in which the exhaust pipe usually runs. The point from which the exhaust pipe only runs vertically upwards to the roof of the building is usually the inlet of the exhaust pipe into the chimney.Complete here means that the heat storage channel surrounds the waste heat conducting device over its entire length and its entire surface area, whereby the surface area of ​​the waste heat conducting device is the boundary of the waste heat conducting device with respect to the environment, i.e. the wall of the waste heat conducting device.

[0016] A ventilation duct in the sense of the invention means an air-conducting duct that is arranged around the waste heat-conducting device and is limited by a wall from the environment and is in direct contact with the heat storage duct

[0017] The at least one inlet of the ventilation duct enables the targeted supply of air, and the at least one outlet of the ventilation duct enables the discharge of heated air. Thus, the heated air discharged via the at least one outlet can be advantageously used to heat a building.

[0018] In some embodiments, the at least one inlet of the ventilation duct is located outside the heated building envelope. This advantageously ensures the operation of the device as an open fresh air system. "Open" here means that fresh air is supplied from outside the heated building envelope via the at least one inlet.

[0019] In further embodiments, at least one inlet of the ventilation duct is arranged within the heated building envelope. This advantageously ensures the operation of the device as a closed recirculation system. "Closed" here means that air from the heated building envelope is supplied via the at least one inlet.

[0020] In further embodiments, the at least one outlet is arranged within the heated building envelope. This advantageously enables the heating of the building envelope by the air heated by the device according to the invention. In embodiments, the ventilation duct has the same number of outlets as the number of rooms to be heated within the building.

[0021] A heat storage medium in the sense of the invention means a storage device for thermal energy that enables the generation of heat and its temporally decoupled use.

[0022] A latent heat storage material, as defined by the invention, refers to materials that change their state of matter during the charging and discharging process, for example, from solid to liquid or vice versa, and are also referred to as phase-change materials (PCMs). Phase-change materials can be organic, inorganic, or metallic. Examples of such materials include salts, paraffins, and aluminum-silicon alloys.

[0023] A thermochemical heat storage material within the meaning of the invention refers to materials that store heat through endothermic and exothermic reactions and are also referred to as sorption storage materials. Examples of such materials are silica gel and zeolites.

[0024] A sensible heat storage material, as defined by the invention, refers to materials that change their temperature during the charging and discharging process. Examples of sensible heat storage materials include water, mineral building materials such as concrete, and organic building materials such as wood, or various types of subsoil, such as clay or rock.

[0025] In embodiments, multiple heat storage media are arranged within the heat storage channel. The multiple heat storage media can each be different latent heat storage materials, different thermochemical, or different sensible heat storage materials. The multiple heat storage materials can also be latent heat storage materials, thermochemical, and sensible heat storage materials. This advantageously allows for large temperature ranges to be covered and enables efficient heat recovery across the entire waste heat temperature profile in the waste heat-conducting device.

[0026] In preferred embodiments, the at least one heat storage channel is arranged within the at least one ventilation channel.

[0027] Advantageously, the at least one heat storage duct and the at least one ventilation duct are in direct contact with each other or also in thermal contact with each other, so that heat can be efficiently transferred between the heat storage duct and the ventilation duct.

[0028] In embodiments, the ventilation duct completely surrounds the heat storage duct over the entire length of the heat storage duct.

[0029] In preferred embodiments, the at least one ventilation duct is arranged within the at least one heat storage duct.

[0030] Advantageously, the at least one heat storage duct and the at least one ventilation duct are in direct contact with each other or also in thermal contact with each other, so that heat can be transferred between the heat storage duct and the ventilation duct.

[0031] In preferred embodiments, the device comprises exactly one heat storage channel and one ventilation channel, and the heat storage channel is arranged around the waste heat conducting device in such a way that the waste heat conducting device runs within the heat storage channel, and the waste heat conducting device and the heat storage channel are in direct contact with each other.

[0032] Advantageously, such a device is easy to implement, particularly in new buildings. Furthermore, the waste heat-conducting device and the heat storage duct are in direct thermal contact with each other, thereby advantageously increasing the efficiency of heat transfer. In some embodiments, both the waste heat-conducting device and the heat storage duct, as well as the heat storage duct and the ventilation duct, are in direct thermal contact with each other. This means that the waste heat-conducting device is directly and completely surrounded by the heat storage duct, and the heat storage duct is directly and completely surrounded by the ventilation duct. This can increase the efficiency of heat transfer.

[0033] In embodiments, the device comprises a plurality of heat storage channels and a plurality of ventilation channels, wherein the heat storage channels are each arranged in spatial proximity around the waste heat conducting device, so that the plurality of heat storage channels surround the waste heat conducting device without being in direct contact with it.

[0034] Such a device is advantageously easy to retrofit in existing buildings. In embodiments, the multiple heat storage channels are arranged in spatial proximity around the waste heat-conducting device. In the context of the invention, spatial proximity means that heat transfer via radiation is possible. In further embodiments, a ventilation duct is arranged within each of the multiple heat storage channels, with the ventilation duct being in direct contact with a respective heat storage channel. The number of multiple ventilation ducts is equal to the number of multiple heat storage channels, so that a ventilation duct is arranged within each heat storage channel.

[0035] In preferred embodiments, the at least one heat storage medium is arranged in layers within the at least one heat storage channel.

[0036] In the context of the invention, "layered" means that the heat storage media are arranged along the temperature profile in the waste heat-conducting device. This advantageously enables efficient heat recovery, since, in embodiments adapted to the temperature profile of the waste heat-conducting device, the heat storage medium suitable for a specific temperature range is arranged in the heat storage channel.

[0037] In embodiments, sensitive heat storage materials or thermochemical heat storage materials are arranged in the heat storage channel surrounding the waste heat-conducting device in regions of the waste heat-conducting device that have high waste heat temperatures of 100°C to 600°C, preferably 200°C to 600°C, particularly preferably 300°C to 600°C. In further embodiments, latent heat storage materials are arranged in the heat storage channel surrounding the waste heat-conducting device in regions of the waste heat-conducting device that have waste heat temperatures of up to 100°C, preferably up to 200°C, particularly preferably up to 300°C.

[0038] To ensure efficient heat recovery within the aforementioned waste heat temperature ranges of up to 100°C, preferably up to 200°C, particularly preferably up to 300°C, or from 100°C to 600°C, preferably 200°C to 600°C, particularly preferably 300°C to 600°C, it may be advantageous if different latent heat storage materials or different sensible or thermochemical heat storage materials are arranged in embodiments. This allows the appropriate heat storage material to be selected for all temperatures within the respective ranges.

[0039] In preferred embodiments, the device further comprises at least one device for generating an air flow within the at least one ventilation duct.

[0040] In some embodiments, the at least one device for generating an air flow within the at least one ventilation duct is a fan. In further embodiments, the at least one device for generating an air flow is arranged at the at least one inlet and / or at the at least one outlet of the at least one ventilation duct.

[0041] In further embodiments, the at least one device for generating an air flow is a ventilation system of the building that generates a planned negative pressure.

[0042] In preferred embodiments, the device further comprises a device for controlling the air flow.

[0043] This can advantageously achieve complete discharge of the heat storage material and increase heat recovery.

[0044] A device for controlling the air flow comprises at least one device for detecting the charge state of the at least one heat storage material, a device for detecting the interior air temperature, a device for detecting the outside air temperature, a device for detecting the time, and a controller for controlling the at least one device for generating an air flow within the at least one ventilation duct. Advantageously, the device for controlling the air flow can be used to set an air flow to be generated by the device for generating an air flow that is suitable for maximum heat transfer. Furthermore, the device for controlling the air flow advantageously enables automated shutdown of the device when the at least one heat storage material is completely discharged.Another advantage is that the air flow control device allows the stored heat energy to be accessed as needed.

[0045] In embodiments, control is based on time, on the indoor air temperature or on the outside air temperature.

[0046] Devices for detecting the indoor air temperature and the outdoor air temperature include, for example, thermometers. Devices for detecting the charge level of a heat storage material include, for example, heat flow plates or temperature sensors, thermocouples. The data thus detected regarding the indoor air temperature, outdoor air temperature, and / or the charge level of a heat storage material serve as input variables for controlling the at least one device for generating an air flow. In embodiments, the at least one device for generating an air flow can be controlled by means of a microcontroller, a PLC controller, or integrated into the control system of the building's ventilation system.

[0047] In preferred embodiments, the waste heat conducting device is an exhaust gas line of a combustion plant.

[0048] This can advantageously increase the efficiency of the combustion system, reduce fuel consumption and increase the interior air temperature.

[0049] A combustion plant within the meaning of the invention is a plant for the combustion of fuels, where the fuels can be gaseous, liquid, or solid. Exhaust pipes from combustion plants are usually routed through chimneys, thus the device according to the invention can advantageously be arranged within the chimney.

[0050] In some embodiments, the waste heat-conducting device is an exhaust pipe of a solid fuel combustion plant. Advantageously, the heat recovery yield is highest in solid fuel combustion plants due to the high waste heat temperatures.

[0051] A further aspect of the invention relates to the use of a device according to the invention for heat recovery and return of the recovered heat to waste heat-conducting devices.

[0052] In preferred embodiments, a device according to the invention for heat recovery and recirculation of the recovered heat is used in an exhaust gas line of a combustion plant.

[0053] For the realization of the invention, it is also expedient to combine the above-described inventive embodiments, embodiments and features of the claims. Examples of implementation

[0054] The invention will be explained in more detail below using an exemplary embodiment. The exemplary embodiment refers to embodiments of the invention and is intended to describe the invention without limiting it. The invention is explained in more detail with the aid of drawings. Fig. 1 an embodiment of a device for heat recovery from waste heat conducting devices and for returning the recovered heat in plan view, Fig. 2 shows a further embodiment of a device for heat recovery from waste heat-conducting devices and for returning the recovered heat in plan view, Fig. 3 an embodiment of a device for heat recovery from waste heat conducting devices and for returning the recovered heat in the sectional view of a building, Fig. 4 shows a further embodiment of a device for heat recovery from waste heat-conducting devices and for returning the recovered heat in a sectional view of a building.

[0055] Fig. 1 shows an embodiment of a device for heat recovery from a waste heat-conducting device 1 and recirculating the recovered heat in a plan view of a chimney 1.1, in which the waste heat-conducting device 1 is guided in some embodiments. In one embodiment, the waste heat-conducting device 1 is an exhaust gas line of a combustion plant 1, preferably a solid fuel combustion plant, which runs in a chimney 1.1. A heat storage duct 2 is arranged around the exhaust gas line 1 such that the exhaust gas line 1 runs within the heat storage duct 2 and the exhaust gas line 1 and the heat storage duct 2 are in direct thermal contact with one another. A ventilation duct 3 is arranged such that the heat storage duct 2 runs within the ventilation duct 3.

[0056] Fig. 2 shows a further embodiment of a device for heat recovery from a waste heat-conducting device 1 and recirculation of the recovered heat in a plan view of a chimney 1.1, in which the waste heat-conducting device 1 is guided in some embodiments. In one embodiment, the waste heat-conducting device 1 is an exhaust pipe of a combustion plant 1, preferably a solid fuel combustion plant, which runs in a chimney 1.1. Several heat storage channels 2 are arranged in spatial proximity around the exhaust pipe 1 so that heat transfer can occur via thermal radiation. A ventilation duct 3 is arranged around each of the several heat storage channels 2 such that the ventilation duct 3 runs within the heat storage channel 2.

[0057] Fig. Figure 3 shows an embodiment of a device for heat recovery from waste heat-conducting devices and for returning the recovered heat in a sectional view of a building 4. A building 4 can be seen in a sectional view. In the building 4, e.g., an apartment building, several combustion systems 5 are arranged. Each of the combustion systems 5 is connected to a waste heat-conducting device 1, a flue gas line 1. The flue gas line 1 is guided vertically upwards within a chimney 1.1 to the roof of the building 4. Also visible is a heat storage duct 2, which is arranged around the flue gas line 1, so that the heat storage duct 2 and the flue gas line 1 are in direct thermal contact with each other. A ventilation duct 3 is arranged around the heat storage duct 2 and is in direct thermal contact with the heat storage duct 2. The arrangement of the flue gas line 1, the heat storage duct 2, and the ventilation duct 3 corresponds in plan view to the Fig. 1. Also visible in Fig. 3, that the ventilation duct 3 has an inlet 6 and several outlets 7. The inlet 6 is arranged outside the heated building envelope, and the several outlets 7 are arranged inside the heated building envelope. Also visible is a device for generating an air flow 8 within the ventilation duct 3, designed as a fan. In this embodiment, fresh outside air is supplied to the ventilation duct 3 via the inlet 6, which is heated by the heat stored in the heat storage duct 2 and exits into the building 4 via the outlets 7. This enables the device for recovering heat from waste heat-conducting devices and for returning the recovered heat to operate as an open fresh air system.

[0058] Fig. Figure 4 shows an embodiment of a device for heat recovery from waste heat-conducting devices and for returning the recovered heat in a sectional view of a building 4. A building 4 can be seen in a sectional view. In the building 4, e.g., an apartment building, several combustion systems 5 are arranged. Each of the combustion systems 5 is connected to a waste heat-conducting device 1, a flue gas line 1. The flue gas line 1 is guided vertically upwards within a chimney 1.1 to the roof of the building 4. Also visible is a heat storage duct 2, which is arranged around the flue gas line 1, so that the heat storage duct 2 and the flue gas line 1 are in direct thermal contact with each other. A ventilation duct 3 is arranged around the heat storage duct 2 and is in direct thermal contact with the heat storage duct 2. The arrangement of the flue gas line 1, the heat storage duct 2, and the ventilation duct 3 corresponds in plan view to the Fig. 1. Also visible in Fig. 4, that the ventilation duct 3 has an inlet 6 and several outlets 7. The inlet 6 and the several outlets 7 are each arranged within the heated building envelope. Also visible is a device for generating an air flow 8 within the ventilation duct 3, designed as a fan. In this embodiment, air from the heated building envelope is supplied to the ventilation duct 3 via the inlet 6, which air is heated by the heat stored in the heat storage duct 2 and exits into the building 4 via the outlets 7. This enables the device for recovering heat from waste heat-conducting devices and for returning the recovered heat to operate as a closed recirculation system. Reference symbol 1 waste heat conducting device 1.1 Chimney 2 heat storage channel 3 ventilation duct 4 buildings 5 Distillation plant 6 Entrance 7 Outlet 8 Device for generating an air flow within the ventilation duct QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] CN 212 746 533 U

[0004] EP 3 467 419 A1

[0005] WO 18 00760 A1

[0006] WO 2004 / 046632 A1

[0007] EP 1 562 000 A1

[0008]

Claims

[1] Device for heat recovery from waste heat-conducting devices and for returning the recovered heat, comprising at least: • at least one heat storage channel arranged around a waste heat conducting device, • and at least one ventilation duct, wherein the ventilation duct has at least one inlet and at least one outlet, wherein at least one heat storage medium is arranged in the heat storage duct and the heat storage medium is selected from latent heat storage materials, thermochemical and sensible heat storage materials. [2] Device according to claim 1, characterized by that the at least one heat storage channel is arranged within the at least one ventilation channel. [3] Device according to claim 1, characterized by , the at least one ventilation duct is arranged within the at least one heat storage duct. [4] Device according to claim 2, characterized bythat the device comprises exactly one heat storage channel and one ventilation channel, and the heat storage channel is arranged around the waste heat conducting device in such a way that the waste heat conducting device runs within the heat storage channel, and the waste heat conducting device and the heat storage channel are in direct contact with each other. [5] Device according to claim 3, characterized by that the device comprises a plurality of heat storage channels and a plurality of ventilation channels, and the heat storage channels are each arranged in spatial proximity around the waste heat conducting device, so that the plurality of heat storage channels surround the waste heat conducting device without being in direct contact with it. [6] Device according to one of claims 1 to 5, characterized by that the at least one heat storage medium is arranged in layers within the at least one heat storage channel. [7] Device according to one of claims 1 to 6, characterized by that the device further comprises at least one device for generating an air flow within the at least one ventilation duct. [8] Device according to claim 7, characterized by that the device further comprises a device for controlling the air flow. [9] Device according to one of claims 1 to 8, characterized by that the waste heat-conducting device is an exhaust pipe of a combustion plant. [10] Use of a device according to one of claims 1 to 9 for heat recovery and return of the recovered heat to waste heat conducting devices. [11] Use of a device according to one of claims 1 to 9 for heat recovery and recirculation of the recovered heat to an exhaust gas line of a combustion plant.

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