GB2142136A

GB2142136A - Heating apparatus including a heat pump

Info

Publication number: GB2142136A
Application number: GB08414034A
Authority: GB
Inventors: Stephen Forbes Pearson
Original assignee: Star Refrigeration Ltd
Current assignee: Star Refrigeration Ltd
Priority date: 1983-06-01
Filing date: 1984-06-01
Publication date: 1985-01-09
Also published as: GB8414034D0

Abstract

The flue 7 of an oil-fired boiler 4 supplying water radiators 10 in an office area 2 contains the evaporator 6 of a heat pump 5 supplying a heat exchanger 15 in a factory area 3. A heat exchanger 17 in the heat pump circuit supplies heat to the boiler circuit 12. To defrost the evaporator 6 the heat pump compressor 14 may be switched off and the speed of the evaporator fan 18 reduced. <IMAGE>

Description

SPECIFICATION Heating apparatus The present invention relates to heating apparatus and in particular to improvements in the performance and economy thereof.

The use of heat pumps as a means of space heating has become increasingly attractive in recent years. A major problem which remains is that the coefficient of performance of heat pumps falls with the ambient temperature as the heating requirement rises. One solution is to make special provision for supplementary heating means for use when the ambient temperature falls below a certain value.

Both the capital cost and running costs of such means are relatively high.

It is an object of the present invention to avoid or minimise one or more of the above disadvantages.

At many sites requiring space heating there are provided relatively high-grade heating means, for example, for heating offices, based on fossil-fuel combustion. In practice a significant amount of the available heat energy from the fuel is lost in the flue gases. Moreover the absolute amount of heat lost in this way increases as the ambient temperature falls and the heating requirement rises.

According to the present invention there is provided a heating apparatus comprising a first, fossilfuel combustion, heating means and a second, heat pump, heating means wherein said heat pump is formed and arranged for extracting heat, in use, at least partly from the flue gases of the first heating means.

With a heating apparatus of the present invention there is obtained a significantly more economic mode of heating together with a more economic form of apparatus insofar as the coefficient of performance of the heat pump moiety is substantially maintained or even improved as the heating requirement increases.

Further preferred features and advantages of the present invention will appear from the following detailed description given by way of example of a preferred embodiment illustrated with reference to the accompanying drawing in which; Figure 1 is a general arrangement plan.

Figure 1 shows a typical industrial site 1 having an office area 2 constituting a higher grade space heating load requiring space heating to about 20"C and a factory area 3 having a lower grade space heating load requiring space heating only to about 15"C.

Tho office block 2 is heated with the aid of a first, fossil-fuel heating means such as an oil-fired boiler 4. The factory area 3 is heated with the aid of a heat pump 5 having a heat extraction heat exchanger means 6 disposed in the flue pipe 7 of the boiler 4.

In use of the system as the office space heating load rises so does the heat available for extraction in the boiler flue gases thereby enabling the correspondingly rising factory space heating load to be satisfied in a simple and economic manner.

In more detail it may be seen that in the illustrated example various conventional features may be included such as thermostatic valves 8 arranged for operation by suitable, optionally remote, temperature sensors 9 to control heating by radiators 10; and a water circulating pump 11 arranged for circulating water through the heating circuit 12 heated by the boiler 4; whilst the heat pump circuit 5 includes an expansion valve 13, a compressor 14, heat rejection heat exchange means 15, conveniently fan-assisted 16, and a discharge line heat exchanger 17 for direct transfer of heat to the boiler heated heating circuit from the heat pump heating circuit.

An important additional advantage provided by the present invention is in connection with defrosting of the heat extraction heat exchanger. In general all conventional heat pumps are subject to frosting to a greater or lesserextentwhich results in reduced heat extraction, and are therefore provided with special means such as reverse-cycle operation for heating of the heat exchanger to melt the frost. Such means add significantly to the cost and complexity of the installation. With the present invention the tendency to frost formation is in any event significantly reduced due to the use of a substantially unique arrangement in which the heat energy source fluid temperature rises with the heating load.When defrosting of the heat exchanger 6 does however become necessary this can be achieved very simply by merely switching off the compressor 14, possibly also reducing the speed of the fan 18 provided to assist the air flow over the heat exchanger 6, and hence the speed of the gas flow over the heat exchanger 6, and allowing the hot flue gases to warm the heat exchanger 6 and melt the frost thereon.

1. A heating apparatus comprising a first, fossilfuel combustion, heating means and a second, heat pump, heating means wherein said heat pump heating means is formed and arranged for extracting heat, in use, at least partly from the flue gases of the first heating means.

2. Heating apparatus as claimed in claim 1 wherein the heat pump heating means comprises a heat pump circuit containing a heat exchange fluid, and including a heat exchange means disposed in thermal contact with the interior of a flue gas conduit means of the first heating means, and downstream thereof a compressor, a heat rejection heat exchange means disposable in use of the apparatus in thermal contact with a zone to be heated, and an expansion valve means.

3. Heating apparatus as claimed in claim 2 wherein is provided a defrost means comprising control means formed and arranged for switching off the compressor when defrosting of the heat extraction heat exchange means is required, whereby the latter is defrosted by the flow of the flue gases thereover.

4. Heating apparatus as claimed in claim 2 or claim 3 wherein said heat pump circuit includes a discharge line heat exchanger downstream of the compressor and upstream of the heat rejection heat exchange means, which discharge line heat ex

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Heating apparatus The present invention relates to heating apparatus and in particular to improvements in the performance and economy thereof. The use of heat pumps as a means of space heating has become increasingly attractive in recent years. A major problem which remains is that the coefficient of performance of heat pumps falls with the ambient temperature as the heating requirement rises. One solution is to make special provision for supplementary heating means for use when the ambient temperature falls below a certain value. Both the capital cost and running costs of such means are relatively high. It is an object of the present invention to avoid or minimise one or more of the above disadvantages. At many sites requiring space heating there are provided relatively high-grade heating means, for example, for heating offices, based on fossil-fuel combustion. In practice a significant amount of the available heat energy from the fuel is lost in the flue gases. Moreover the absolute amount of heat lost in this way increases as the ambient temperature falls and the heating requirement rises. According to the present invention there is provided a heating apparatus comprising a first, fossilfuel combustion, heating means and a second, heat pump, heating means wherein said heat pump is formed and arranged for extracting heat, in use, at least partly from the flue gases of the first heating means. With a heating apparatus of the present invention there is obtained a significantly more economic mode of heating together with a more economic form of apparatus insofar as the coefficient of performance of the heat pump moiety is substantially maintained or even improved as the heating requirement increases. Further preferred features and advantages of the present invention will appear from the following detailed description given by way of example of a preferred embodiment illustrated with reference to the accompanying drawing in which; Figure 1 is a general arrangement plan. Figure 1 shows a typical industrial site 1 having an office area 2 constituting a higher grade space heating load requiring space heating to about 20"C and a factory area 3 having a lower grade space heating load requiring space heating only to about 15"C. Tho office block 2 is heated with the aid of a first, fossil-fuel heating means such as an oil-fired boiler 4. The factory area 3 is heated with the aid of a heat pump 5 having a heat extraction heat exchanger means 6 disposed in the flue pipe 7 of the boiler 4. In use of the system as the office space heating load rises so does the heat available for extraction in the boiler flue gases thereby enabling the correspondingly rising factory space heating load to be satisfied in a simple and economic manner. In more detail it may be seen that in the illustrated example various conventional features may be included such as thermostatic valves 8 arranged for operation by suitable, optionally remote, temperature sensors 9 to control heating by radiators 10; and a water circulating pump 11 arranged for circulating water through the heating circuit 12 heated by the boiler 4; whilst the heat pump circuit 5 includes an expansion valve 13, a compressor 14, heat rejection heat exchange means 15, conveniently fan-assisted 16, and a discharge line heat exchanger 17 for direct transfer of heat to the boiler heated heating circuit from the heat pump heating circuit. An important additional advantage provided by the present invention is in connection with defrosting of the heat extraction heat exchanger. In general all conventional heat pumps are subject to frosting to a greater or lesserextentwhich results in reduced heat extraction, and are therefore provided with special means such as reverse-cycle operation for heating of the heat exchanger to melt the frost. Such means add significantly to the cost and complexity of the installation. With the present invention the tendency to frost formation is in any event significantly reduced due to the use of a substantially unique arrangement in which the heat energy source fluid temperature rises with the heating load.When defrosting of the heat exchanger 6 does however become necessary this can be achieved very simply by merely switching off the compressor 14, possibly also reducing the speed of the fan 18 provided to assist the air flow over the heat exchanger 6, and hence the speed of the gas flow over the heat exchanger 6, and allowing the hot flue gases to warm the heat exchanger 6 and melt the frost thereon. CLAIMS

4. Heating apparatus as claimed in claim 2 or claim 3 wherein said heat pump circuit includes a discharge line heat exchanger downstream of the compressor and upstream of the heat rejection heat exchange means, which discharge line heat ex change is formed and arranged for heat rejection to a heating circuit of said first heating means.

5. A heating installation comprising a heating apparatus according to any one of claims 1 to 4 wherein said first and second heating means are mounted with respective heat rejection heat exchange means thereof in thermal contact with respective ones of higher and lower heating load zones.

6. Heating apparatus substantially as described hereinbefore with particular reference to the accompanying drawing.