METHOD FOR LIMITING A SUPPLY FLOW IN A HEAT TRANSFER SYSTEM

• US 20150369494A1
• Filed: 06/23/2015
• Published: 12/24/2015
• Est. Priority Date: 06/24/2014
• Status: Active Grant

• Current Assignee: Grundfos Holding A/S (POUL DUE Jensen's FOND)
• Original Assignee: Grundfos Holding A/S (POUL DUE Jensen's FOND)
• Inventors: NIELSEN, Brian Kongsgaard, SKOVMOSE KALLESE, Carsten
• Granted Patent: US 10,184,671 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F24D 19/1006 for water heating systems
• CPC Class Codes: F24D 19/1012 by regulating the speed of a pump
• CPC Class Codes: F24D 19/1015 using a valve or valves
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A method for limiting a supply flow (q_S) in a heat transfer system which includes a supply conduit (10) with a supply flow (q_S) and with a supply entry temperature (T_S), and at least one load circuit (2) with a load pump (20) which provides a load flow (q_L) with a load entry temperature (T_L) and a load exit temperature (T_R). The load entry temperature (T_L) is set by way of changing the supply flow (q_S), wherein the supply flow (q_S) is limited to a maximal flow (q_S, max), taking into account at least one temperature detected in the load circuit (2). A heat transfer system, in which this method is realized, is also provided.

Claims

1. A method for limiting a supply flow in a heat transfer system, the method comprising the steps of:

providing the heat transfer system such that the heat transfer system comprises;

a supply conduit with a supply flow and a supply entry temperature; and

at least one load circuit with a load pump which provides a load flow with a load entry temperature and a load exit temperature;

setting the load entry temperature by changing the supply flow; and

limiting the supply flow to a maximal flow while taking into account at least one temperature detected in the load circuit.

2. A method according to claim 1, wherein the provided heat transfer system further comprises at least one heat exchanger between the supply conduit and the load circuit.

3. A method according to claim 1, wherein the provided heat transfer system comprises at least one mixing device which mixes a load exit flow at least partly with the supply flow.

4. A method according to claim 1, wherein the supply flow is set on the basis of the load flow and of one or more temperature signals which are determined in the provided heat transfer system, on the basis of the supply entry temperature, the load entry temperature and the load exit temperature.

5. A method according to claim 1, wherein the supply flow is indirectly limited by way of at least one:

limiting a thermal power flow in the load circuit;

limiting the load exit temperature;

limiting a difference between the load exit temperature and the load entry temperature.

6. A method according to claim 1, wherein for at least two input variables, in each case a maximal supply flow or a variable monotonic related to the maximal supply flow is determined on the basis of one of the input variables, and subsequently one of the determined maximal supply flows is selected for limiting the supply flow.

7. A method according to claim 1, wherein the supply flow is limited by limiting at least one of a speed of the load pump and a speed of a supply pump and by limiting an opening degree of a valve affecting the supply flow.

8. A method according to claim 1, wherein the supply flow is limited by limiting a control variable of a pressure controller or temperature controller affecting the supply flow.

9. A method according to claim 1, wherein the supply flow is limited by limiting a control variable of a control loop which regulates a load temperature and/or a load pressure in the load circuit including limiting a differential pressure across the load pump.

10. A heat transfer system comprising:

a supply conduit for connection to a fluid supply;

a return conduit for connection to a fluid return;

at least one load circuit;

a load pump operatively connected to the load circuit;

a flow control device regulating a supply flow in the supply conduit, wherein the flow control device is configured to regulate a load entry temperature at an entry of the load circuit by way of regulating the supply flow;

at least one temperature sensor operatively connected to the load circuit; and

at least one limitation controller configured to directly or indirectly limit a supply flow to the load circuit to a predefined maximum in dependence on at least one temperature signal from the at least one temperature sensor.

11. A heat transfer system according to claim 10, further comprising at least one of a heat exchanger between the supply conduit and the load circuit and a mixing conduit which connects the exit of the load circuit to the supply conduit at a mixing point.

12. A heat transfer system according to claim 10, further comprising at least one of a pressure controller and a temperature controller operatively connected to the load circuit, wherein at least one of the pressure controller and the temperature controller is coupled to the limitation controller such that a control variable of the at least one of the pressure controller and the temperature controller can be limited by the limitation controller to a maximal value.

13. A heat transfer system according to claim 10, wherein the limitation controller is configured in a manner such that the limitation controller compares a thermal power flow in at least one of the load circuit and the load exit temperature and a difference between the load exit temperature and the load entry temperature, with an associated limit value and defines a maximum for a variable for setting the supply flow.

14. A heat transfer system according to claim 10, wherein the at least one temperature sensor is at least one of a temperature sensor arranged at the entry of the load circuit and detects a load entry temperature and a temperature sensor which is arranged at the exit of the load circuit and detects a load exit temperature.

15. A heat transfer system according to claim 10, wherein the flow control device comprises at least one of a supply pump which regulates the supply flow and a supply valve which regulates the supply flow.

16. A heat transfer system according to claim 10, wherein the load pump is configured for detecting a flow through the load circuit and is related to the flow control device for transmitting a signal corresponding to the detected flow.

17. A heat transfer system according to claim 10, wherein at least one of the flow control device and the limitation controller are integrated into a load pump assembly forming the load pump.

18. A heat transfer system supply flow method comprising the steps of:

providing a heat transfer system comprising a supply conduit for connection to a fluid supply, a return conduit for connection to a fluid return, at least one load circuit, a load pump operatively connected to the load circuit, a flow control device for regulating a supply flow in the supply conduit, wherein the flow control device is configured to regulate a load entry temperature at an entry of the load circuit by way of regulating the supply flow, at least one temperature sensor operatively connected to the load circuit, at least one limitation controller configured to directly or indirectly limit a supply flow to the load circuit to a predefined maximum in dependence on at least one temperature signal from the at least one temperature sensor;

setting the load entry temperature, with the flow control device, by changing the supply flow; and

limiting the supply flow, with the at least one limitation controller, to a predefined maximum in dependence on at least one temperature signal from the at least one temperature sensor.

19. A method according to claim 18, wherein the provided heat transfer system further comprises at least one heat exchanger between the supply conduit and the load circuit.

20. A method according to claim 18, wherein the provided heat transfer system comprises at least one mixing device which mixes a load exit flow at least partly with the supply flow.