Heating system and method for controlling a heating system

Patent metadata

Field	Value
Publication number	US-9341383-B2
Application number	US-201113990707-A
Country	US
Kind code	B2
Filing date	Dec 6, 2011
Priority date	Dec 8, 2010
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

A heating system includes a flow circuit carrying working fluid at a set flow temperature to a heat emitting section, an electricity driven heat pump having a first heat exchanger, and a fuel fired boiler having a second heat exchanger. The first and second heat exchangers arc connected to the flow circuit to heat the working fluid in succession. A coefficient of performance (COP Set Flow Temperature ) of the heat pump and a break even coefficient of performance (BECOP) are determined, and the COP Set Flow Temperature and BECOP compared. The BECOP is electricity price/fuel price*boiler thermal efficiency. If the COP Set Flow temperature is smaller than the BECOP in a first hybrid mode, an intermediate flow temperature is determined, the heat pump is operated to heat the working fluid to the intermediate flow temperature and the boiler is operated to heat the working fluid to the set flow temperature.

First claim

The invention claimed is:

1. A heating system comprising:
a flow circuit arranged and configured to carry a flow of a working fluid at a set flow temperature to a heat emitting section in order to perform heating of a space;
an electricity driven heat pump having a first heat exchanger connected to the flow circuit to transfer heat to the working fluid;
a fuel fired boiler having a second heat exchanger connected to the flow circuit to transfer heat to the working fluid downstream of the first heat exchanger; and
a control configured
to determine a coefficient of performance (COP Set Flow Temperature ) of the heat pump for the set flow temperature,
to determine a break even coefficient of performance (BECOP), the BECOP being an electricity price divided by a fuel price multiplied by a thermal efficiency of the boiler,
to compare the COP Set Flow Temperature with the BECOP, and
if the COP set Flow Temperature is smaller than the BECOP in a first hybrid mode,
to determine an intermediate flow temperature at which the COP Intermediate Flow Temperature is higher than the BECOP,
to operate the heat pump so that the working fluid is heated to the intermediate flow temperature by the first heat exchanger and
to operate the boiler so that the working fluid is heated from the intermediate flow temperature to the set flow temperature by the second heat exchanger.

2. The heating system according to claim 1 , further comprising
a pump, the control being further configured to control the pump so as to reduce a flow rate of the working fluid so that a return temperature of the working fluid returned to the first heat exchanger is lowered in the first hybrid mode.

3. The heating system according to claim 2 , wherein
the control is further configured to increase or decrease the set flow temperature stepwise with a time interval in between two consecutive steps, after the flow rate of the working fluid has been reduced, in the first hybrid mode.

4. The heating system according to claim 3 , further comprising
a room sensor arranged and configured to measure a room temperature in the space to be heated, and
at least one of a value of each step and a length of each time interval is dependent on the difference between the desired room temperature in the space to be heated and the measured room temperature.

5. The heating system according to claim 4 , wherein
the control is further configured to control the pump so as to increase the flow rate of the working fluid stepwise, when a maximum allowable flow temperature has been reached and the measured room temperature in the space to be heated is lower than the desired room temperature.

6. The heating system according to, claim 1 , wherein
the control is further configured to determine whether the heat pump is capable of satisfying a required heating demand to heat the working fluid to the set flow temperature or the intermediate flow temperature and to determine an operation mode based on the determination.

7. The heating system according to claim 6 , wherein
the control is further configured to operate the heat pump and the boiler in the first hybrid mode if the heat pump is capable of satisfying the required heating demand to heat the working fluid to the intermediate flow temperature.

8. The heating system according to claim 6 , wherein
the control is further configured to operate the heat pump only in a heat pump mode if the COP Set Flow Temperature is higher than the BECOP and the heat pump is capable of satisfying the required heating demand to heat the working fluid to the set flow temperature.

9. The heating system according to claim 6 , wherein
the control is further configured to operate the boiler and the heat pump in a second hybrid mode if the COP Set Flow Temperature is higher than the BECOP and the heat pump is not capable of satisfying the required heating demand to heat the working fluid to the set flow temperature.

10. The heating system according to claim 6 , wherein
the control is further configured to operate the boiler only in a boiler only mode if the COP Set Flow Temperature is smaller than the BECOP and the heat pump is not capable of satisfying the required heating demand to heat the working fluid to the intermediate flow temperature.

11. The heating system according to claim 1 , wherein
the flow circuit is hydraulically separated between the heat pump and the boiler.

12. A method for controlling a heating system including
a flow circuit arranged and configured to carry a flow of a working fluid at a set flow temperature to a heat emitting section in order to perform heating of a space;
an electricity driven heat pump having a first heat exchanger connected to the flow circuit to transfer heat to the working fluid;
a fuel fired boiler having a second heat exchanger connected to the flow circuit to transfer heat to the working fluid downstream of the first heat exchanger;

the method comprising:
determining a coefficient of performance (COP Set Flow Temperature ) of the heat pump for the set flow temperature;
determining a break even coefficient of performance (BECOP), the BECOP being an electricity price divided by a fuel price multiplied by a thermal efficiency of the boiler
comparing the COP Set Flow Temperature with the BECOP; and
if the COP Set Flow Temperature is smaller than the BECOP in a first hybrid mode
determining an intermediate flow temperature at which the COP Intermediate Flow Temperature is higher than the BECOP,
operating the heat pump so that the working fluid is heated to the intermediate flow temperature by the first heat exchange, and
operating the boiler so that the working fluid is heated from the intermediate flow temperature to the set flow temperature by the second heat exchanger.

13. The method according to claim 12 , further comprising
in the first hybrid mode, reducing the flow rate of the working fluid so that a return temperature of the working fluid returned to the first heat exchanger is lowered.

14. The method according to claim 13 , further comprising
in the first hybrid mode, increasing or decreasing the set flow temperature stepwise with a time interval in between two consecutive steps, after the flow rate of the working fluid has been reduced.

15. The method according to claim 14 , further comprising
measuring a room temperature in the space to be heated, and
at least one of a value of each step and a length of each time interval is determined dependent on the difference between the desired room temperature in the space to be heated and the measured room temperature.

16. The method according to claim 15 , further comprising
in the first hybrid mode, increasing the flow rate of the working fluid stepwise, when a maximum allowable flow temperature has been reached and the measured room temperature in the space to be heated is lower than the desired room temperature.

17. The method according to claim 12 , further comprising
determining whether the heat pump is capable of satisfying a required heating demand to heat the working fluid to the set flow temperature or the intermediate flow temperature and
at least one of
operating the heat pump and the boiler in the first hybrid mode if the heat pump is capable of satisfying the required heating demand to heat the working fluid to the intermediate flow temperature,
operating the heat pump only in a heat pump mode if the COP Set Flow Temperature is higher than the BECOP and the heat pump is capable of satisfying the required heating demand to heat the working f

Assignees

• Aspeslagh Bart
• Debaets Stefanie
• Daikin Ind Ltd
• Daikin Europe Nv

Inventors

• Aspeslagh Bart
• Debaets Stefanie

Classifications

• Y02B30/12

  Hot water central heating systems using heat pumps · CPC title

• F24D2200/123

  Compression type heat pumps · CPC title

• F24D2200/046

  Condensing boilers · CPC title

• F24D12/02 Primary

  having more than one heat source (using heat pumps, in water central heating systems F24D3/18; in air central heating systems F24D5/12; in systems using heat storage masses F24D11/02) · CPC title

• F24D3/08

  in combination with systems for domestic hot-water supply · CPC title