GB2107444A - Absorber heat pump arrangement - Google Patents

Abstract

For the purpose of increasing the efficiency of a absorber heat pump arrangement having an expeller (3) adapted to be fed with rich coolant solution from an absorber (13), flue gases leaving a burner (1) are arranged to flow directly through a flue gas heat carrier medium heat exchanger (22) in the event of a higher output requirement, particularly when the burner (1) is operating in its higher performance states. The flow to the heat exchanger (22) is controlled by way of a valve (24). When not required, the heat exchanger (22) can be bypassed by means of a line (27) controlled by a valve (28). <IMAGE>

Description

SPECIFICATION Parallel-bivalent operating heat pump arrangement The invention relates to a parallel-bivalent operating heat pump arrangement.

A heat pump arrangement of this type is known which has a burner producing flue gases which are fed to an empeller fed with rich coolant solution, and has a condenser, vapourizer and absorber and a connection line for the heat carrier medium between the absorber and the forward flow line.

A heat pump arrangement of this kind, which operates in a parallel-bivalent manner as an absorber heat pump and boiler, is described in West German patent application P30 18705.4 in which a flue gas heat carrier medium heat exchanger is located in the heat carrier medium forward flow line and is connected in series with the expeller with respect to the flue gas. A heat pump arrangement of this kind which operates in a parallel-bivalent manner has the advantage that the heating requirement of, for example, a building, can be met all the year round solely by the absorber heat pump arrangemenu with a minimum of fuel consumption.

An object of the invention is to improve the efficiency of a heat pump arrangement of the aforegoing type.

In accordance with the invention, there is provided a parallel-bivalent operating absorber-type heat pump arrangement comprising a burner which produces flue gases which are fed to an expeller fed with rich coolant solution, and having a condenser, vapourizer and absorber, and a flue gas heat carrier medium heat exchanger which is located in a connecting line for heat carrier medium between the abosorber and a forward flow line which is directly subjectable to flueggas by way of a controllable shut-off element.

An advantage of the invention resides in the fact that, in view of the direct transfer of heat from the flue gas to the heat carrier medium, the heatexchanging surfaces can be kept relatively small, particularly in the highly-stressed, expensive parts, such as the expeller.

In one embodiment, the absorber can be supplied with weak solution from the expeller by way of a further heat exchanger and by way of a relief valve, and a by-pass line for weak solution, which bypasses said further heat exchanger, is provided with a valve which opens the latter by-pass line when the outer temperature drops to a predetermined value.

The latter embodiment has the advantage, that with the same overall efficiency of the heat pump arrangement, the flue gas heat carrier medium heat exchanger can be dimensioned for a lower performance, that is to say, its expense and spatial requirements are reduced. This means that, with the retention of the design of the flue gas heat carrier medium heat exchanger, the overall performance of the heat pump arrangement can be increased by the present measures.

One embodiment of the invention is described hereinafter by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic illustration of the basic construction of a system in accordance with the invention and Figure 2 shows an advantageous structural arrangement.

The lines and circuits in Figure 1 for the various media are identified as follows.

A gaseous coolant, such as NH3, is indicated by two parallel lines. A solid line is used when the coolant is present in a liquid phase. If this line is provided with dots, the line is a line for weak solution. A dash-dot line indicates a line for a rich solution. A line interrupted with large spaces indicates a line for the heat carrier medium, preferably heating water, and a line interrupted with short spaces indicates an air line. Flue gas lines are indicated by continuous lines having sloping lines passing therethrough.

An expeller 3 of known construction having a rectificator 4 and a dephlegmator 5 is fed by a burner, generally designated 1, by way of a flue gas line 2. The expeller3 supplies gaseous coolant to a condenser 6 which is located in a heating water return line 7 and in which the heat of condensation is transferred to the heating water forming the heat carrier medium. The heat exchanger forming the dephlegmator 5 already mentioned is also located in the heating water circuit.

The coolant liquified in the condenser 6 flows by way of a cold exchanger 8 into a vapourizer 9 whose chief components are a valve 10 and a heat exchanger 11.The pressure of the liquid coolant fed is relieved from, for example, 18 bar to approximately 2 bar downstream of the valve 10.Heat is supplied in the heat exchanger 11 by, inter alia, extraction of heat from inlet air 12, so that the coolant flows, in a gaseous state, into the cold exchanger 8 at a temperature of approximately -5 to 1 0 C, and into an absorber 13 at a temperature of approximately 7 to 20"C. A weak solution is fed to the absorber 13 from the expeller 3 by way of a heat exchanger 14 and a pressure-reducing valve 15, a pressure reduction from, for example, approximately 18 bar to approximately 2 bar being effected by the valve 15, and the absorber 13 feeds a rich solution to the expeller 3 by way of a pump 16 and the abovementioned heat exchanger 14. The heat produced by absorption is absorbed by the heating water flowing through a serpentine pipe 17 in the absorber 13.

For the purposes of the invention, the guidance of the flue gases is of special importance. After leaving the expeller 3, the flue gases first flow through a flue gas heating water heat exchanger 18, so that they heat the heating water, coming from the serpentine pipe 17 in the absorber 13, to a high temperature and then flow into a chimney or the like by way of a line 19.

The arrangement as described thus far is known from the German patent application mentioned initially.

In the present arrangement, a flue gas heating water heat exchanger 22 is disposed in the connecting line 20 which is located between the absorber 13 and a heating water forward flow line 21 and which also includes the flue gas heating water heat exchan ger 18 already mentioned, the flue gas being fed directly to the flue gas heating water heat exchanger 22, tat is to say, directly from the burner 1, by way of an individual flue gas line 23. A flue gas flap 24 serving as a shut-off element is located in the flue gas line 23 and is opened by means of a servo motor 5 when the burner 1 is switched to its highest output stage. This is indicated by the line 26.

n order to prevent the heating water from flowing through the heat exchanger 22 during the operating periods in which the flue gas heating water heat exchanger 22 is not subjected to flue gas, thereby possibly giving rise to undesirable heat losses, a by-pass line 27, by-passing the heat exchanger 22, is provided with a shut-off member in the form of a valve 28. As is indicated by the line 29, the valve 28 is aiso actuated in synchronism with the changingover of the burner 1 to its higher output stage. The servo motor 25 can also be used for this purpose. It will be appreciated that the two shut-off elements 24 and 28 are actuated in opposition to one another.

The flue gas flap 24 is opened when the burner 1 is changed over to its higher output stage, so that flue gas flows through the heat exchanger 22, whereas the valve 28 is then closed, so that all the heating water also flows through the heat exchanger 22.

The path of the flue gases is indicated in Figure 2.

The solid arrows indicate those flue gases which ficwthrnugh the parts of the arrangement which form the actual heat pump, while flue gases also fioN in conformity with the broken arrows during parallel-bivalent operation, The parts already illustrated in Figure 1 are provided with the same reference numerals in Figure 2. It will be seen that the expeller3 and a series arrangement comprising the two flue gas heating water heat exchangers 18,22 are disposed parallel to one another or adjacent to one another on the burner 1. The heat exchanger 22 is located directly adjacent the burner 1 and is connected thereto by way of the individual flue gas line 23, while the flue gases flow to the expeller 3 by way of the individual flue gas line 2.The flue gases which have flowed through the expeller 3 are also introduced into the heat exchanger 18 by the flue gas line 30 extending above the heat exchanger 22. Thus, all the exhaust gases are utilized twice. During pure heat pump operation, the heat exchanger 22 is shut off by the flue gas flap 24, although the flue gases flowing through the expeller 3 also enter the heat exchanger 1 8. During parallel-bivalent operation, that is to say, when the flue gas flap 24 is open, the flue gases flowing through the heat exchanger 22 also enter the heat exchanger 18, so that heat is also extracted from the heat exchangers at two locations.

Referring to Figure 1 again, a by-pass line 40, by-passing the heat exchanger 14, for weak solu tions is provided with a valve 41 which is controlled by signals from a temperature sensor (not illus trated) for the atmospheric air temperature or the regulated forward flow temperature indicative there of, so that the by-pass line 40 opens, that is to say, it becomes effective, when the atmospheric tempera ture has dropped to a predetermined value. The weak solution, by-passing the heat exchanger 14, then flows directly into the absorber 13, that is to say, at, for example, an atmospheric temperature of -10 C. Flash gas is released upon expansion of the hot weak solution at the absorber inlet downstream of the relief valve 15. The solution then cools to boiling temperature at absorber pressure.The flash gas is re-absorbed when cooling by means of the heating water flowing through the serpentine pipe 17. This heat of absorption is additionally transferred to the heating water. Thus, the by-pass line 40 opened at these low temperatures transfers that heat to the heating water in the serpentine pipe 17 which is internally transferred in the heat exchanger 14 in the absence of the by-pass line 40 or at higher temperatures when the valve 41 is thus closed.

In the event of failure of the vapourizer 9, the valve 41 is fully opened manually or automatically by, for example, a relay, and is closed again when the temperature drops below the above-mentioned value of the atmospheric temperature.

The advantage of these measures can be shown to best advantage with reference to a numerical example: If, in the absence of the by-pass 40, the flue gas heating water heat exchanger 22 has to be designed for an output of 13 kW, and the expeller 3 has to be designed for an output of 8.5 kW, it is sufficient, when the by-pass is provided, to design the he3t exchanger 22 for an output of 8.5 kW owing tG tk ' higher temperature difference in the absorber 1 13 Thus, the spatial requirement of the heat exchange.

is reduced without a loss of performance.

Claims (8)

1. A parallel-bivalent operating absorber-type heat pump arrangement comprising a burner which produces flue gases which are fed to an expeller fed with rich coolant solutions, and having a condenser, vapourizer and absorber, and a flue gas heat carrier medium heat exchanger which is located in a connecting line for heat carrier medium between the absorber and a forward flow line and which is directly subjectable to flue gas by way of a controliable shut-off element.

2. A heat pump arrangement as claimed in claim 1, including a by-pass for the heat carrier medium located in parallel with said heat exchanger and incorporating a further shut-off element.

3. A heat pump arrangement as claimed in claim 1 or 2, in which the burner has at lest two power stages and is arranged to open the shut-off element fortheflue gas upon change-overto a higher power stage.

4. A heat pump arrangement as claimed in claim 2 or 3, wherein the burner has at least two power stages and is arranged to close the shut-off element for the heat carrier medium upon change-over to a higher power stage.

5. A heat pump arrangement as claimed in any of claims 1 to 4, wherein after flowing through the expeller the flue gases are fed to a further flue gas heat carrier medium heat exchanger in said heat carrier medium forward flow line.

6. A heat pump arrangement as claimed in claim 5, wherein the expeller on the one hand, and a series arrangement of the two heat exchangers on the other hand, are disposed adjacent to one another on the burner, the firstmentioned heat exchanger being located in the series arrangement between the burner and the point of entry of a flue gas line leading from the expeller to the second-mentioned heat exchanger, and the shut-off element for the flue gas being disposed in an individual connection piece between the burner and the first mentioned heat exchanger.

7. A heat pump arrangement as claimed in any of claims 1 to 6, wherein the absorber is supplied with weak solution from the expeller by way of a further heat exchanger and by way of a relief valve, and a by-pass line for weak solution, which by-passes said further heat exchanger, is provided with a valve which opens the latter by-pass line when the outer temperature drops to a predetermined value.

8. A parallel-bivalent operating absorber-type heat pump arrangement substantially as hereinbefore described with reference to the accompanying drawings.