WO1987007703A1

WO1987007703A1 - Heating system including a heat accumulator

Info

Publication number: WO1987007703A1
Application number: PCT/SE1986/000279
Authority: WO
Inventors: Gunnar Sigvard Nilsson
Original assignee: Gunnar Sigvard Nilsson
Priority date: 1984-12-11
Filing date: 1986-06-10
Publication date: 1987-12-17

Abstract

Heating system, including a heat source, from which a heated liquid medium is arranged to flow a heated circuit (2), arranged to first pass through a heat accumulator (3) with a liquid medium, and by means of one or a number of coils (4, 5) emit or absorb heat in relation to the liquid medium existing within the heat accumulator (3) and surrounding the coil/coils (4, 5), and that an outgoing part of the circuit (2) from the heat accumulator (3) is arranged to heat one or a number of radiators (R) utilized for room heating. The heat source is advantageously a heat pump, the heated circuit (2) being the secondary circuit - the heated circuit - of the heat pump. The liquid medium existing within the heat accumulator (3) is arranged to heat water for tapping, circulating in a closed circuit system, and with coils (4, 5) included in the heated circuit (2), and coils (7, 8) for heating of water for tapping, being arranged alternating in relation to each other in the height direction of extension for the heat accumulator (3). Additional heat to the liquid medium existing in the heat accumulator (3) can be supplied by one or a number of electrically operated immersion heaters (12, 13), or by arranging said liquid medium to flow via a circuit (14) past a water tank, heated by means of a furnace (17). The flow in the heated circuit (2), which after leaving the heat accumulator (3) feeds a radiator circuit, is maintained constant by means of a by-pass circuit (9) and a pressure operated valve means (10) in said circuit (9).

Description

HEATING SYSTEM INCLUDING A HEAT ACCUMULATOR

The present invention relates to a heating system including a heat accumulator.

Heating of rooms is often combined with heating of water for tapping, performed in two separate circuits, a closed circuit for radiator water utilized for room heating purposes, and an open circuit for water intended for tapping. The hot tapping water should have a temperature in the region of 50-70 C, whereas the radiator water can be maintained at a o lower temperature, usually within the region of 40-50_. C, but depending on the annual season. It is previously known to use a heat exchanger or heat accumulator, including a tank with a liquid medium, arranged to store heat emitted from one or a number of heat sources, and including heat absorbing tubular members, having a through flow of radiator water and water for tapping.

The object of the present invention is to disclose a heating system, being a combination of a heat source, a heat store and a radiator circuit, facilitating a simplified design of the heat generating unit, and in embodiments where the heat generating unit comprises of a heat pump with a liquid medium in the secondary circuit, the possibility of an improved grade of efficiency for the heat pump is also offered. This feature is related to the fact that the grade of efficiency for such a heat pump is strongly related to the difference in temperature between outgoing and incoming flow in the secondary side of the heat pump, and that such a favourable difference of temperature is achieved in a heating system according to the present invention. The heat accumulator included in the heating system makes it also possible to store heat to be used for heating of hot water for tapping, and also use as added heat for heating radiators when an increased heat is required.

The heating system according to the present invention includes a heat source, from which a heated liquid medium is arranged to flow in a heated circuit, arranged to pass through a heat accumulator with a l quid medium, and by means of one or a number of coils emit or absorb heat in relation to the the liquid medium existing within the heat accumulator, and it is mainly characterised in that a from the heat accumulator outgoing part of the circuit in direction from the heat accumulator is arranged connected in a return flow path to the heat source via one or a number of radiators utilized for room heating, and that in the heated circuit included heat emitting coils, and coils for heating of water for tapping, are arranged alternating in relation to each other in the vertical direction of extension for the heat accumulator. When the heat source comprises of a heat pump, the heated circuit comprises of the secondary circuit - the heated circuit - of the heat pump.

A basic embodiment of a heating system according to the present invention is more fully described below with reference to the accompanying drawing, which is a basic circuit diagram of such an embodiment.

In said example of an embodiment, a heat pump is shown having a primary circuit i (the evaporation and condensation circuit), and a heated secondary circuit 2. A flow of a liquid medium in the secondary circuit 2 heats the contents of a heat accumulator 3. Said contents comprises of a liquid medium, e.g. water. Heat emission from the secondary circuit 2 is accomplished efficiently by shaping said circuit 2 into two coils, 4 and 5 respectively, surrounded by the heat accumulator 3, and through which the medium of the secondary circuit flows.

According to a first function, the coils 4, 5 included in the secondary circuit 2 are used to emit heat to the liquid medium existing within the heat accumulator 3, and according to a second function, the coils 4, 5 are utilized to absorb additional heat from the heat accumulator 3.

The heat accumulator also includes two internally connected coils 7, 8, forming a part of the circuit for tapping water. These two coils 7, 8 are arranged located in an alternating relationship to the coils 4, 5 included in the secondary circuit 2, i.e. with a first coil 7 located interposed between the coils 4, 5, and with a second coil 8 located above the upper coil 4, as shown in the circuit diagram. The part of the secondary circuit 2 serving as a return circuit from the heat accumulator 3 is utilized to supply heat to a number of radiators R, the throughflow of which is assumed to be controlled by means of thermostatically controlled valve means.

In order to accomplish a high grade of efficiency for the heat pump, and thus high power, a well adjusted volume flow in the secondary circuit 2 is a requirement. In order to meet this requirement, the secondary circuit 2 is arranged with a by-pass circuit 9, connecting the secondary circuit 2 at two points, located before, respectively after, the points of connection for supply and return flow of radiator water to the radiators R, i.e. the radiator circuit. The flow through the by-pass circuit is controlled by means of a valve means 10, which is controlled by the pressure within the secondary circuit 2. Changes in the flow requirements within the radiator circuit do thereby not influence the total flow within the secondary circuit 2, since the total flow is maintained at a constant level by means of the by-pass circuit 9. In order to accomplish flow circulation within the secondary circuit 2, said circuit 2 also includes a circulation pump 11 having a variably adjustable flow.

Temperature sensing is performed at the outlet for the secondary circuit 2 from the heat pump, and when the sensed temperature reaches a predetermined maximum value, a temperature sensing thermostat causes the heat pump to stop.

During extreme conditions, the heat required by the radiator circuit may exceed the total heat obtainable from the heat source. This requirement is met by the fact that the heat accumulator is arranged with an electric heating means being an immersion heater 12, located adjacent to the coil 5. To facilitate an additional supply of heat, and for the same reason, to the water for tapping, an immersion heater 13 is also arranged in the heat accumulator adjacent to the coils 7, 8 utilized for heating of tapping water.

The heating system according to the present invention results in a number of advantages. It is thus possible for the heating system to operate and store heat in the heat accumulator 3 when energy is available, and independent of required output. A buffer of stored heat is accomplished in such a way, that the liquid contents of the heat accumulator 3 on the one hand uses the known feature that hot water raises in direction upwards, on the other hand due to the fact that any definite layers with different temperature levels are not formed within the heat accumulator 3, but rather a gradually increased temperature from the bottom portion in direction upwards, which results in a high grade of efficiency and favourable operation.

The medium transported in the secondary circuit 2 for emission of heat from the heat source to the heat accumulator 3 and the radiator circuit, can be given a volume flow adapted to each size of heat pump, whereby the heat pump always operates at a suitable operating point adapted to give maximum efficiency, which results in the best economy. The heat absorbed by the secondary circuit 2 from the heat pump is used completely, since the heat is emitted to the heat accumulator 3, the water for tapping, as well as the radiators R. The medium existing in the secondary circuit 2 thereafter returns well cooled to the heat pump, in order to take up heat again.

Furthermore, only a first function of the secondary circuit 2 has been described above, but as mentioned previously, also a second function may exist. This second function exists when the heat suppl ed from the heat pump to the heat accumulator 3 is insufficient for the present requirement. In this case the electrically heated immersion heaters 12 are switched on, and if required also the heaters 13, thereby further heating the liquid medium existing within the heat accumulator 3. The secondary circuit 2 can hereby by means of the coils 4, 5 take up this additionally supplied heat for emission to the radiators R, and the v/ater for tapping is also heated further.

For applications where electrical power is not available in the required extent for direct heating by means of immersion heaters 12, 13, there are also other possible ways to accomplish supply of additional heat to the heat accumulator 3, and an example of such a solution is shown in the left part of the circuit diagram.

According to this modification, a circuit 14 is connected to the upper and lower portion of the heat accumulator 3, including a thermically controlled valve 15, a by-pass circuit 16, a furnace 17 with a water tank connected to the circuit 14, and a circulation pump 18 for accomplishing flow within the circuit 14. The water in associated tank is heated by means of the furnace 17, and circulated through the circuit i4 by means of the circulation pump 18 in such a way, that the heated water is supplied to the upper portion of the heat accumulator 3. The flow is controlled by the thermically controlled valve 15 in such a fashion, that heated water is only supplied in such a volume, that the circulation within the heat accumulator 3 is not disturbed. The volume of water that is not allowed to flow through the thermically operated valve 15 is returned via the by-pass circuit 16 to the water tank by the furnace 17. Heating by means of the furnace 17 is continued until the heat accumulator 3 has reached desired temperature level, whereafter the combustion in the furnace 17 is interrupted.

As shown, the heat accumulator 3 is also arranged with an expansion circuit 19, connected at the upper portion of the heat accumulator 3, and including a water lock, or alternatively an expansion tank.

The example of an embodiment of a heating system according to the present invention described above comprises of a combination of a heat pump and a heat accumulator 3, and examples of further heat sources indicated to supply additional heat. However, it should be emphasized, that also other heat sources than heat pumps can be used as main heat heat sources in combination with a heat accumulator 3 and possibly required additional heat sources for supplying additional heat, and that the present invention thus in no way is restricted to use in connection with heat pumps. Furthermore, the number of coils within the heat accumulator 3 can obviously be further varied as desired with regard to number and intended use for each case of application. The heating system according to the present invention is thus in no way restricted to the embodiment described above, but it can be further varied within the scope of the inventive thought and the following claims.

Claims

C L A I M S

i. Heating system, including a heat source, from which a heated l quid medium is arranged to flow in a heated circuit (2), arranged to pass through a heat accumulator (3) with a liquid medium, and by means of one or a number of coils (4, 5) emit or absorb heat in relation to the the liquid medium existing within the heat accumulator (3), c h a r a c t e r i s e d i n, that a from the heat accumulator (3) outgoing part of the circuit (2) in direction from the heat accumulator (3) is arranged connected in a return flow path to the heat source via one or a number of radiators (R) utilized for room heating, and that in the heated circuit (2) included heat emitting coils (4, 5), and coils (7, 8) for heating of water for tapping, are arranged alternating in relation to each other in the vertical direction of extension for the heat accumulator (3).

2. Heating system according to claim 1, c h a r a c t e r i s e d i n, that the heat source comprises of a heat pump, and that the heated circuit (2) comprises of the secondary circuit - the heated circuit - of the heat pump.

3. Heating system according to any one of claims 1 and 2, c h a ¬ r a c t e r i s e d i n, that the heat accumulator (3) is arranged with one or a number of electrically operated immersion heaters (12) located adjacent to the bottom portion of the heat accumulator (3), and/or electrically operated immersion heaters (13) located above the uppermost coil (4) included in the heated and heat emitting circuit (2), arranged to supply additional heat.

4. Heating system according to any one of claims 1 - 3, c h a ¬ r a c t e r i s e d i n, that the upper and lower parts of the heat accumulator (3) are arranged communicating with a circuit (14) including a water tank heated by a furnace (17), and that a circulation pump (18) is arranged to supply water heated by means of the furnace (17) to the upper part of the heat accumulator (3), and that a corresponding volume simultaneously is drained from the lower part of the heat accumulator (3) to the water tank heated by means of the furnace (17).

5. Heating system according to claim 4, c h a r a c t e r i s e d i n, that the circuit (14) includes a by-pass circuit (16) and a temperature controlled valve means (15), said valve means (15) being arranged between the water tank heated by means of the furnace (17) and the point of inlet to heat accumulator (3) from the circuit (14), the volume of liquid not being supplied to the heat accumulator (3) via the valve means (15) be ng recirculated by means of the by-pass circuit (16) to the circuit (14) at a point located before the inlet of same to the water tank.

6. Heating system according to any one of claims 1 - 5, c h a - r a c t e r i s e d i n, that the heated circuit (2), by the portion which connects the outlet of said circuit (2) from the heat accumulator (3) with a heat source, and which is connected to a radiator circuit, is arranged with a by-pass circuit (9) facilitating byflow of the radiator circuit, and that said by-pass circuit (9) includes a pressure controlled valve means (10), arranged to maintain the total flow through the radiator circuit and the by-pass circuit at a predetermined level.

7. Heating system according to any one of claims 1 - 6, c h a - r a c t e r i s e d i n, that the upper portion of the heat accumulator (3) is arranged connected to an expansion pipe, including a water lock or alternatively being connected to an expansion tank.

8. Heating system according to any one of claims 1 - 6, c h a - r a c t e r i s e d i n, that flow circulation in the heated circuit (2) is accomplished ny means of a circulation pump (11) having a variably adjustable flow.