DE102017006068A1 - Device for the energy-efficient ventilation of buildings by using waste heat and environmental heat - Google Patents

Abstract

So far, the ventilation of residential buildings is mainly carried out by window ventilation without heat recovery, because known systems with supply and exhaust duct and heat exchanger are too expensive and can also be retrofitted. By preheating the supply air with wastewater heat can be achieved with limited effort a significant energy savings in the ventilation. Due to the comparatively simple air flow, the system is not only suitable for new buildings, but also for retrofitting existing buildings. 1 shows an example of a supply system with wastewater preheating.

Description

The invention describes a device for energy-efficient ventilation of residential buildings, possibly also suitable commercial buildings, by using the waste heat and possibly environmental heat. Depending on the design, cooling can also take place in summer.

In residential buildings, all rooms must be ventilated to remove carbon dioxide and water vapor as well as various pollutants and odors and to supply oxygen. Since it is now state of the art to use tight windows and doors, the rooms must be supplied either by manual, regular ventilation or by an automatically operating system with fresh air. At present, few residential buildings have a ventilation system, although this dust removal of the supply air, a uniform ventilation, possibly a noise reduction and, depending on the version, an energy saving can be achieved.

Known ventilation systems with energy saving use a separate duct system for supply air and exhaust air, wherein the supply air is warmed up with a heat exchanger by the warm exhaust air. To overcome the pressure drop in the exhaust system usually a second blower is necessary. In addition, it comes especially in winter to condensation and possibly icing in the heat exchanger. Condensation can cause biofilms (bacteria, molds, etc.) to form on the heat transfer surfaces, requiring them to be cleaned more often.

There have also been described systems in which the supply air is preheated by a laid in the ground heat exchanger. Since the soil in Germany has a temperature of about 10 ° C on average, the preheating is rather low. In addition, this system can often not be used for reasons of space and it requires elaborate earthworks. In addition, there is a risk that radon gets from the ground into the supply air.

Various systems have also been described for the use of wastewater heat. In most cases, it preheats the cold water entering the water heater. By direct heat exchange, only a small part of the heat required for hot water production can be applied. There is also the danger that multiply unwanted germs in fresh water medium temperature. Such systems are in the patents DE 2905251 A1 . DE 432467 A1 . DE 8512297 U1 . DE 20 2007 006 465 U1 described.

The hot water can be used in Germany over most of the year with solar energy, z. B. with a solar thermal system, done.

The present invention can be achieved with limited effort a significant energy savings in the ventilation of residential buildings. The largest energy savings occur in winter, when little sun shines. For a house with 4 inhabitants, the annual energy saving is estimated at about 1000-2400 kWh.

The supply air is centrally filtered, optionally preheated by a geothermal heated countercurrent heat exchanger, heated by the wastewater heat exchanger and fed through one or more Zuluftkanäle in the living or lounge area. The exhaust air is decentralized via several simple outlets preferably out of rooms with more air pollution (toilet, bathroom, kitchen) to the outside. Due to the comparatively simple air flow, the system is not only suitable for new buildings, but also for retrofitting existing buildings.

The countercurrent heat exchanger is thereby flowed through with a heat transfer fluid (eg brine or water / glycol mixture), which in turn z. B. is heated or cooled in a geothermal heat exchanger by the relatively constant temperature in the ground. In very cold outside temperatures, this can provide some of the heat needed to heat the supply air with very little energy (only the energy for the circulation pump) ( 1 ). In warmer outdoor temperatures, the pump remains switched off.

In summer operation, the supply air is via a bypass flap 19 passed the wastewater tank. If a heat exchanger 15 is installed, can be cooled if necessary, with very little energy consumption, the coolant temperature by a control valve 17 is adjusted so that the desired air temperature is reached and condensate is avoided. This is z. B. with a in the air flow behind the heat exchanger 15 Built-in sensor for the relative humidity (not shown) this measured and opened by the control the control valve so far that a maximum humidity value of z. B. 90% is not exceeded.

Since the waste water is discontinuous, but the ventilation is continuous, a storage medium is required. In the present invention, the waste water itself serves as a storage medium. At the same time, the wall of the storage container serves as a heat transfer surface to the supply air.

1 shows the central ventilation unit. It means: 1 : Supply air, 2 : Air filter, 3 : Blower, 4 : Air duct to the rooms to be ventilated, 5 : Wastewater feed, 6 : Emptying valve, 7 : Overflow, 8th : Emergency overflow, 9 : Venting, 10 : outer container, 11 : inner container 12 : helical air duct, 13 : Drain, 14 : Venting, 15 : Countercurrent heat exchanger, 16 : Circulation pump for heat transfer fluid, 17 : Control valve, 18 : Geothermal heat exchanger, 19 : Bypass flap.

The supply air 1 gets in the air filter 2 filtered and by the blower 3 first through the countercurrent heat exchanger 15 and then through the space between the two containers 10 and 11 blown, where it is helically from bottom to top, ie in countercurrent to the wastewater out. The leadership of the air can either only by appropriately directed blowing or by a helical guide element 12 respectively.

In normal operation is the valve 6 (Claims 1-4) closed (in a vertical position). The inner container 11 is up to the height of the overflow 7 filled with sewage. The incoming, warm wastewater I collect because of the lower density in the upper part of the container 11 and displaces already cooled waste water from the lower part of the container. Only the parts of the wastewater are used, which are not too polluted (shower water, bath water, water from washing and possibly dishwasher, no toilet waste water). In the container 11 forms a temperature stratification, so that the heat transfer to the air takes place in countercurrent. The material for the inner container must be corrosion resistant, eg. B. PE or PP. A conical container shape has the advantage that optionally used for both containers the same output part and the flow cross-section over the vertical distance of the two containers can be adjusted. As heat transfer between air and vessel wall improves with increasing flow velocity, a suitable flow rate should be set. The temperature of the vessel wall can not normally be much lower than the air temperature. Thus, no condensation should take place. About the bypass valve 19 If the temperature is too low, the air can be led past the container in order to prevent condensation. If the air is not to be heated, it is also passed past the container.

If necessary, the temperature stratification in the tank can be improved by several waste water inlets at different heights, to which the wastewater feed is switched depending on the temperature.

One problem that makes the use of wastewater heat difficult is the formation of deposits, sediments and wall layers. As a result, both lines can be clogged and the heat transfer through the container wall can be worsened. In order to avoid a total failure of the outflow at a blockage or freezing of the lower part of the container, is an emergency overflow 8th intended.

In addition, the sturdy and reliable drain valve 6 automatically slurried at appropriate intervals. Due to the relatively large flow during sludge, large parts of the sediment and possibly also floating impurities are discharged and the valve is kept clean.

The drain valve consists of several pipe or hose pieces, which are alternately guided up and down (claim 1). The rising in the direction of discharge pipe sections fill with wastewater, while the air from the sloping pipe sections can not escape. As a result, the hydrostatic pressure of the water column in the waste water tank 11 compensated, so that the valve is closed. When the valve is tilted so that the pipe sections are substantially horizontal, the back pressure drops and the tank deflates. When the valve is closed and the container is filled, the valve is heavier due to the partially filled (ascending) pieces of pipe than when it is open, deflated. This difference in weight can be used to operate in both directions by tensioning a spring or lifting a weight when opening and using the stored energy to close it later (claim 3). Alternatively, a float can also be used in the container for closing, which floats when the container is full and is pulled down when the container is empty by its weight (claim 4). Thus, only two electromagnetically released locks are needed to operate the valve from the controller. In order to reduce the energy losses by slurrying, the sludging takes place in winter only with relatively cold container contents.

To clean the container wall, one or more floats can be used, which migrate downwards during the slurrying and thereby clean the wall with a suitable cleaning agent such as a brush or wire (claim 5). The pressure on the wall can be done by a permanent magnet in the float, which attracts an outside of the container mounted iron rail (claim 6, 2 ).
It means: 1 : Container wall, 2 Image: Iron rail, 3 Photos: Ballast, 4 : Swimmer, 5 : Permanent magnet, 6 : Brush.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The 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

• DE 2905251 A1 [0005]
• DE 432467 A1 [0005]
• DE 8512297 U1 [0005]
• DE 202007006465 U1 [0005]

Claims (7)

Device for energy-efficient ventilation of buildings by using the waste heat, consisting of a central supply air unit with air filter, waste heat exchanger with normally filled with waste inner wastewater tank surrounded by an optionally externally thermally insulated outer second container, fan, one or more supply air ducts with air outlets in the spaces to be ventilated and exhaust air outlets, wherein the supply air is helically guided from bottom to top through the space between the two containers and warmed by the heat transfer from the inner waste container, characterized in that for occasionally emptying the container a valve with two or more miteinender connected, in the closed state alternately upwardly and downwardly guided chambers, tube or hose sections is used, which thereby prevails with two or more series-connected water columns on the container bottom Balancing pressure and thereby closing the drain and can be opened by tilting the pipe elements in the horizontal. Apparatus according to claim 1, characterized in that the opening of the valve takes place after unlocking by tilting in the horizontal by the weight of the filled valve. Apparatus according to claim 1, characterized in that the closing of the deflated valve after unlocking by tilting in the vertical by a voltage when opened energy storage (spring or weight) takes place. Apparatus according to claim 1, characterized in that the closing of the valve takes place after unlocking by tilting in the vertical by the weight of a float in the then empty wastewater container. Apparatus according to claim 1, characterized in that for cleaning the wall of the waste water tank, one or more floats are used, which move when emptying by its own weight down and thereby clean the wall with a mechanical cleaning agent. Apparatus according to claim 5, characterized in that the float (s) used to clean the inner wall of the waste water tank are provided with one or more permanent magnets so that the float (s) are pulled against the inner wall, either the wall of the tank being made of a ferromagnetic material or there is suitable ferromagnetic material outside the container near the container wall. Apparatus according to claim 1, wherein the air flow before entering the wastewater heat exchanger flows through a heat exchanger, which is operated with a suitable, in a geothermal heat exchanger or in a built-in heat exchanger water or cooled liquid, characterized in that in cooling only so much cold Liquid from the earth or water heat exchanger is mixed into the liquid circuit of the air-flow heat exchanger, that the dew point of the supplied air is not exceeded.

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