GB2561688A

GB2561688A - Sectional Boiler

Info

Publication number: GB2561688A
Application number: GB1803040.3A
Authority: GB
Inventors: Klein Rudolf; Marko Armin; Ripplinger Hans-Joachim
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2017-03-10
Filing date: 2018-02-26
Publication date: 2018-10-24
Anticipated expiration: 2038-02-26
Also published as: DE102017204043A1; GB201803040D0; GB2561688B

Abstract

A sectional boiler 10 suitable for heating a liquid 12, comprises a liquid inlet 16 and a liquid outlet 18 suitable for connecting to a heating system (14, Fig. 2). The pressure drop between inlet 16 and outlet 18 is between 35 mbar and 65 mbar. The pressure drop may be mainly in the region of the outlet 18. The temperature of the liquid may increase between the inlet and outlet by between 12 and 18 degrees C. A liquid path (24, Fig. 2) between inlet and outlet may taper in the flow direction. The liquid path may be deflected by several flow elements (26, Fig. 2). Heat exchange with counterflowing heating gases (34, Fig. 2) may occur along the liquid path. The boiler may be comprise several aluminium sections and is particularly suitable for heating water.

Description

(54) Title of the Invention: Sectional Boiler

Abstract Title: Sectional boiler with low pressure drop in liquid channel

Fig.1

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Description

Title

Sectional boiler

The invention relates to a sectional boiler for heating a liquid, in particular heating water, having a liquid inlet and a liquid outlet, each of which can be connected to a heating system.

Prior art

DE 10352272 Al discloses a heat exchanger of a sectional boiler which is produced by casting and has a housing made up of a number of boiler sections through which heating gases circulate, in each of which is disposed at least one passage through which a heating medium circulates and the passage wall thereof across which the heating gases circulate has protrusions to increase the surface area.

The disadvantage of such sectional boilers is that they have a high water content which ensures a low hydraulic pressure loss and thus also relieves the burden on the pumps used but they have a thermal inertia, on the other hand, which is accompanied by energy losses. If the water content is reduced, as is necessary due to the introduction of condensing technology and hence materials such as cast aluminium that are used as a result, the water-side pressure loss increases as a result, thereby making additional boiler pumps and hydraulic separators necessary.

Advantages of the invention

A sectional boiler having the features of the main claim enables additional boiler pumps or hydraulic separators to be avoided but nevertheless enables the water content of the sectional boiler to be kept relatively low. The invention is based on the knowledge that what is essential in achieving this is to keep the pressure drop within a very narrow window of tolerance. This seems trivial because a pressure drop is usually typical of such systems. However, the crux of the invention resides precisely in specifying a defined pressure drop range. With a knowledge of this invention, the skilled person will then be in a position to tweak the respective structural design of different sectional boilers so as to adhere to the narrowly tolerated pressure drop.

If the pressure drop between the liquid inlet and the liquid outlet of the sectional boiler is kept within a range of between 35 mbar and 60 mbar, increased thermal comfort is already possible without having to resort to additional boiler pumps or hydraulic separators. By increased thermal comfort in this context is meant that the boiler can be rapidly brought from a cold state to a warm state and that heat losses will remain low on cooling.

Comfort can be further increased if the pressure drop is limited to a range of between 40 mbar and 60 mbar.

An optimum situation is achieved when the pressure drop between the liquid inlet and the liquid outlet reaches 50 mbar. In this respect, it should be noted that both a rise above and a drop below this value will result in a loss of comfort.

Advantageous embodiments of the sectional boiler defined in the main claim can be achieved on the basis of the features specified in the dependent claims. For example, it has been found to be particularly positive if the pressure mainly drops in the region of the liquid outlet. In other words, the sectional boiler should be constructed such that although a pressure drop occurs through the sectional boiler as such, the main drop in pressure takes place in the region of the liquid outlet.

Thermal comfort is further increased if the liquid flowing from the liquid inlet to the liquid outlet is increased by 12 K to 18 K. This prevents too high a heat loss and increases the control speed. An optimum situation is achieved at a temperature increase of 15 K. This setting preferably applies at so-called nominal operation. Nominal operation refers to the maximum power of a boiler. As a rule, a boiler is operated below nominal operation and only in extreme situations at maximum power, for example if it is necessary to heat domestic water and the living space rapidly.

Under extreme conditions, it has been found that an increase in the liquid temperature of between 47 K and 53 K, in particular 50 K, between the liquid inlet and liquid outlet is of advantage. Extreme conditions prevail when very high flow temperatures are needed, for example.

It is of advantage if a defined liquid path runs between the liquid inlet and liquid outlet. It has also proved to be conducive to the invention if the liquid path tapers in the flow direction.

If flow elements are disposed in the liquid path, the thermal transfer is optimised and furring of the flow path is reduced at the same time.

The liquid path can easily be made larger if it is deflected multiple times in the flow direction. It has proved to be positive if flow elements are disposed in the region of the deflection and/or deflections.

It is also of advantage if a heat exchange with counterflowing heating gases takes place along the liquid path.

Based on a preferred embodiment, the sectional boiler has several sections, which in turn are made from aluminium.

In order to influence the pressure in a specific way, in particular provide the pressure drop in a specific region, an adjusting device may be provided. This adjusting device is preferably provided at the liquid outlet and can adjust the pressure drop and/or flow rate per unit of time in the sectional boiler.

Drawings

The drawings illustrate an example of an embodiment of the sectional boiler proposed by the invention, which will be explained in more detail in the following description. Figure 1 schematically illustrates a section through a sectional boiler along line I-I indicated in Figure 2 and Figure 2 schematically illustrates a section through a sectional boiler along line II-II indicated in Figure 1.

Description

Figures 1 and 2 illustrate a sectional boiler 10 for heating a liquid 12. The liquid 12 is usually so-called heating water which is heated in the sectional boiler 10 and then runs through a heating system 14, where it can selectively emit heat at consumers. The liquid 12 is supplied with heat by a burner 13 which discharges its hot flue gas into a combustion chamber 15.

The sectional boiler 10 has one or more liquid inlets 16 and one or more liquid outlets 18 which can be connected to the heating system 14. As a rule, the so-called flow is connected to the liquid outlet 18 and the so-called return is connected to the liquid inlet 16. To this end, the sectional boiler 10 has an inlet manifold 20 and an outlet manifold 22, which are connected respectively to the liquid inlets 16 and liquid outlets 18.

In the exemplary embodiment, the pressure of the liquid drops by 50 mbar starting from the pressure at the liquid inlet 16 to the pressure at the liquid outlet 18. In other embodiments, it may be sufficient if the pressure drop adheres to a range of 40 mbar to 60 mbar or of 35 mbar to 64 mbar.

The pressure drop depends on the inner friction which the liquid encounters on the path through the sectional boiler. However, this pressure drop need not necessarily occur linearly between the liquid inlet 16 and the liquid outlet 18. In the exemplary embodiment, the pressure mainly drops in the region of the liquid outlet 18. In the exemplary embodiment, this means that 70% to 80% of the pressure drop takes place in this region.

In the sectional boiler 10, the liquid 12 undergoes an increase in temperature of 15 K from the liquid inlet 16 to the liquid outlet 18. This value has proved to be particularly effective, including precisely when the boiler is operated at its maximum power. In the exemplary embodiment, this is 50 kW. In other embodiments, it is sufficient to keep the temperature increase at least in a range of between 12 K and 18 K.

In other embodiments, it is also possible to provide a temperature increase of 50 K, especially if heating has to be run with very high flow temperatures. Again in this instance, it is possible to keep the increase at least in a range of 47 K to 53 K in embodiments that are adapted accordingly.

As may clearly be seen in Figure 2, a liquid path 24 is provided between the liquid inlet 16 and the liquid outlet 18. This liquid path 24 determines the route of the liquid 12 in the sectional boiler and thus forms a directed flow. The liquid path 24 tapers from the liquid inlet 16 to the liquid outlet 18. This being the case, the flow speed of the liquid 12 increases from the liquid inlet 16 to the liquid outlet 18. The highest flow speed is therefore reached in the regions of the highest heat, namely in the region of the combustion chamber 15.

Flow elements 26 are disposed in the liquid path 24 which stabilise the flow direction of the liquid 12 and enable a laminar flow to be maintained across a larger speed range.

As may also be seen in Figure 2, the liquid path 24 is deflected multiple times in the flow direction. These deflection points 28 are created by walls 30 co-operating with the external boundary 32. Due to multiple deflection, a meandering liquid path 24 is created.

In order to stabilise the flow, the flow elements 26 are disposed in the region of the deflection points 28 and thus help the liquid flow to pass the deflection points 28 as calmly as possible.

As may be seen in Figure 1, the liquid inlets 16 are disposed in a bottom region of the sectional boiler 10 so that the liquid 12 flows upwards to the liquid outlet 18 and/or liquid outlets 18. The combustion chamber 15 is disposed in a top region so that the heating gases 34 flow downwards. A flue gas and condensate collecting container 36 is provided in a bottom region. A flue gas discharge 38 is connected to the collecting container on one side. As may be seen, the heat exchange between the liquid 12 and heating gases 34 takes place in counter-flow along the liquid path 24.

As may also be seen from the schematic diagram of Figure 1, the sectional boiler 10 is made up of several individual sections 40 and two terminating sections 42 and 44. The individual sections 40 and the terminating sections 42 and 44 are made from aluminium, in particular cast from aluminium.

As illustrated in Figure 2, an adjusting device 46 may be provided in the region of the liquid outlet 18, by means of which the pressure drop of the liquid 12 and/or the flow rate per unit of time in the sectional boiler 10 can be adjusted. This may be done either by a slide that can be operated from outside or by an integrated valve. The purpose of this is to obtain the greatest pressure drop in the region of the liquid outlet 18.

Claims

1. Sectional boiler (10) for heating a liquid (12), in particular heating water, having a liquid inlet (16) and a liquid outlet (18) which can be connected to a heating system (14), characterised in that the pressure of the liquid (12) drops by 35 mbar to 65 mbar, preferably by 40 mbar to 60 mbar, in particular by 50 mbar, between the liquid inlet (16) and the liquid outlet (18).

2. Sectional boiler as claimed in claim 1, characterised in that the pressure mainly drops in the region of the liquid outlet.

3. Sectional boiler as claimed in one of claims 1 or 2, characterised in that the temperature of the liquid increases by 12 K to 18 K, in particular by 15 K, from the liquid inlet to the liquid outlet.

4. Sectional boiler as claimed in one of claims 1 or 2, characterised in that the temperature of the liquid increases by 47 K to 53 K, in particular by 50 K, from the liquid inlet to the liquid outlet.

5. Sectional boiler as claimed in one of the preceding claims, characterised in that a liquid path runs between the liquid inlet and the liquid outlet.

6. Sectional boiler as claimed in one of the preceding claims, characterised in that the liquid path tapers in the flow direction.

7. Sectional boiler as claimed in one of the preceding claims, characterised in that flow elements are disposed in the liquid path.

8. Sectional boiler as claimed in one of the preceding claims, characterised in that the liquid path is deflected multiple times in the flow direction.

9. Sectional boiler as claimed in one of the preceding claims, characterised in that the flow elements are disposed in the region of the deflection.

10 10. Sectional boiler as claimed in one of the preceding claims, characterised in that a heat exchange with counterflowing heating gases takes place along the liquid path.

11. Sectional boiler as claimed in one of the preceding

15 claims, characterised by several sections made from aluminium.

Intellectual

Property

Office

Application No: GB1803040.3 Examiner: Dr Rhys Williams