Marine thermal system, marine thermal system installed in a marine vessel, marine vessel equipped with a marine thermal system, thermal system control method, and control device

Abstract

The marine thermal system comprises a thermal liquid circuit (10), a pump system (11) for circulating thermal liquid in the thermal liquid circuit (10), a plurality of thermal consumers (20) arranged in parallel in the thermal liquid circuit (10) and in series with respective pressure independent control valves (PICVs) (30), and a controller (12) for controlling the pump system (11). A differential pressure sensor (13) is adapted to sense a differential pressure indicative of a differential pressure across a critical one (30.1a) of said pressure independent control valves, and a signal from said differential pressure sensor (13) is used by the controller (12) as a basis for controlling the pump system.

Description

[Technical field]

[0001] The present invention relates to a thermal system for a marine vessel comprising a thermal liquid circuit, a pump system for circulating a thermal liquid in the thermal liquid circuit, a plurality of thermal consumers arranged in parallel in the thermal liquid circuit and in series with respective Pressure Independent Control Valves (PICVs), and a control device for controlling the pump system. The present invention further relates to a marine vessel comprising the thermal system, a method for controlling the thermal system, and a control device. [Background technology]

[0002] In ships of a certain size, thermal systems such as the cooling systems of the above art are used to provide cooling to a large number of cooling consumers.

[0003] It should be noted that although cooling is the primary objective of the present invention, the present invention may also be used for central heating of a vessel.

[0004] Thus, in this specification, the term "thermal" can be understood as either "cooling" or "heating."

[0005] Considering that in many cases around 20% of a ship's electricity production is used to drive pumps, reducing the energy demand for pumps could result in significant energy savings in ship operations.

[0006] Thermal systems, and in particular cooling systems, use pumps to circulate thermal liquid, and in particular cooling liquid, within liquid circuits which may branch out widely, for example in a ship, where cooling is required, i.e. where there are thermal or cooling consumers.

[0007] For ease of explanation, reference will be made below to cooling.

[0008] Cooling consumers include engines and other mechanical devices, air conditioners, and the like.

[0009] Under some circumstances the cooling demand of the various consumers remains relatively constant, whereas under other circumstances the cooling demand may be lower than normal, for example when the engine is operating at only partial load.

[0010] In thermal or cooling systems of the kind mentioned in the introduction, the amount of thermal or cooling liquid circulated through a given consumer is controlled by a PICV, i.e. Pressure Independent Control Valve. Such valves are known in the art and comprise a pressure absorbing part or mechanism, commonly known as a differential pressure regulator, which absorbs a part of the differential pressure applied to the valve, so that another part of the valve can provide at least approximately the desired flow rate through the valve, which depends on the remainder of the differential pressure, said remainder being regulated by the pressure absorbing part of the valve. The remaining pressure is thus kept constant by the pressure absorbing part of the valve.

[0011] In order to properly regulate the flow rate through the PICV, a certain differential pressure must be applied across the PICV.

[0012] Thus, in prior art thermal or cooling systems, pumping systems are operated at levels that provide sufficient pressure differentials at all points in the thermal or cooling system. Summary of the Invention [Problem to be solved by the invention]

[0013] However, in many cases, a large amount of the differential pressure provided in this way is absorbed by the PIVCs in the system, so operating the pump system at a predetermined high level to ensure sufficient differential pressure at all points in the thermal or cooling system involves a large amount of energy loss.

[0014] The object of the present invention is to reduce such energy losses. [Means for solving the problem]

[0015] In a first aspect, the object is achieved in a thermal system of the kind mentioned in the introduction, characterized in that it comprises a differential pressure sensor adapted to detect a differential pressure indicative of a differential pressure across one of the pressure-independent control valves that is critical, the signal from which is used by the control device as the basis for controlling the pump system.

[0016] The term "critical" in reference to pressure independent control valves (PICVs) should be understood to mean PICVs of a thermal or cooling system that are in danger of developing too low a differential pressure if the pumping energy is reduced to too low a level.

[0017] Expressions such as "differential pressure across an element (e.g. a valve)" and "differential pressure applied to an element (e.g. a valve)" should be understood to mean the difference between the pressure upstream of (just above) the element and the pressure downstream of (just below) the element.

[0018] It should be understood that when selecting which PICVs to consider as critical PICVs in a given thermal or cooling system, consideration should be given to the fact that the differential pressure demands of a given PICV may differ from the differential pressure demands of another PICV.

[0019] The differential pressure sensed or measured by the differential pressure sensor may be the sum of the differential pressure across the thermal consumer and the PICV attached thereto. In such a case, the measured differential pressure is indicative of the differential pressure across the PICV, since if the flow resistance of the thermal consumer is known, at least to an estimated value, the differential pressure across the PICV can be calculated or estimated as an indicated differential pressure based on the measured differential pressure and the known or estimated flow resistance of the thermal consumer.

[0020] With respect to the term "pump system," it should be noted that a pump system may consist of a single pump or may consist of more pumps operating in parallel or series, as is known in the art.

[0021] In one embodiment, the thermal fluid is water, preferably fresh water, where "fresh water" is to be understood as being in contrast to the salty water in which ships typically travel, and thus the term "fresh water" should not be understood as excluding additives such as corrosion inhibitors that are typically added to the circulating fluid of a thermal or cooling system.

[0022] In one embodiment, each of the thermal consumers is placed in series with a pressure independent control valve, so that the total flow of thermal fluid is controlled and balanced by the pressure independent control valve, allowing for superior flow control of thermal or cooling fluid at all points in the system.

[0023] In one embodiment, at least one first thermal consumer is arranged in series with a controllable pressure-independent control valve, preferably with a pressure and / or temperature sensor attached to said first thermal consumer providing a control signal for controlling said controllable pressure-independent control valve. Controllable pressure-independent control valves are known in the art and may comprise a valve body whose position is controlled by a control element, which itself may receive an input from, for example, a temperature sensor, whereby the control element adjusts the position of the valve body to adjust the flow rate through the PICV, i.e. through the thermal or cooling consumer attached to the PICV, so that the temperature detected by the sensor can be kept substantially constant or according to a given scheme. It is also possible for the control element to receive an input from a pressure sensor, or for the PICV to be controlled by an external signal, for example a running signal from a motor or another external signal from an individual consumer requiring cooling or heating.

[0024] Control of the controllable PICVs based on temperature can be based on temperature difference, as an alternative or complement to a specific temperature. Thus, for example, the temperature difference across each consumer can be measured to provide a temperature difference signal for controlling the controllable PICVs. The temperature measurement for control, whether a specific temperature or a temperature difference, can be taken from the thermal fluid strictly speaking, or from the fluid on the second side of a heat exchanger through which the thermal fluid of the thermal fluid circuit flows on the first side.

[0025] Controlling the PICV based on temperature, whether a specific temperature or a temperature difference, can be combined with control based on a running signal, for example. In such a case, at the start of one of the appliances, e.g. an engine, as a respective consumer, it is possible to adjust the PICV to fully open when receiving a running signal prior to receiving a temperature signal. This makes it possible to avoid tripping of the appliance due to too little cooling due to a slow response of the temperature measurement from the cooling / thermal fluid to the rapid heat generation at the start of the appliance.

[0026] In one embodiment, the second thermal consumer comprises a further minor thermal consumer arranged in parallel or series and arranged in common series with a respective second pressure independent control valve, thereby allowing the number of PICVs in the thermal system to be reduced compared to a system in which every consumer is attached to its own PICV.

[0027] In one embodiment, further differential pressure sensors are provided adapted to sense respective differential pressures indicative of the differential pressures of the respective pressure-independent control valves. In particular, it is foreseen that each PICV is provided with or fitted with a respective differential pressure sensor. This may be appropriate, for example, in thermal systems in which it is difficult or impossible to determine which PICV is the critical PICV. This is the case, for example, in thermal systems in which certain thermal consumers are sometimes shut down and essentially removed from (the active part of) the thermal system. In such an embodiment, the control device for controlling the pump system may be adapted to use the indicated differential pressure closest to the differential pressure required for the respective pressure-independent control valve as a basis for controlling the pump system. Thus, it is desirable for the controller to have information of the differential pressure demands of multiple PICVs (PICVs) where the differential pressure is measured, calculated, or indicated, and for each of these PICVs, compare the differential pressure demand with the measured, calculated, or indicated differential pressure of each PICV to determine which PICV has the smallest difference between the measured, calculated, or indicated differential pressure and the differential pressure demand, and then use the differential pressure across that PICV as the basis for controlling the pump system.

[0028] Pressure measurement can be integrated into the PICV via a built-in PT-plug or via a permanently attached pressure (differential) sensor or the like. The output signal from such a pressure sensor can be transferred to the controller separately or can be integrated into the actuator of the PICV and transferred from there to the controller. In this respect, a communication network (such as MODBUS®) can be used. In this way, the PICV and / or the respective actuator can constitute a network that controls the pump rate.

[0029] In one embodiment, the thermal system further comprises a central thermal unit; a branch of the thermal fluid circuit passing through the central thermal unit; a bypass of the thermal fluid circuit bypassing the central thermal unit; a three-way valve for controlling the flow rate through said branch and the flow rate through said bypass; a temperature sensor for measuring the temperature of the stream downstream from said branch and said bypass; and a controller for controlling said three-way valve in response to a signal from the temperature sensor. The central thermal unit can provide a lower or higher temperature thermal fluid depending on whether the thermal system is a cooling or heating system, and the three-way valve allows the fluid from the central thermal unit to be mixed with the thermal fluid flowing through the thermal fluid circuit to obtain a desired stream temperature in the thermal fluid circuit.

[0030] In another embodiment, the thermal system further comprises a central thermal unit comprising a heat exchanger having a primary side and a secondary side, the primary side being part of a thermal fluid circuit of the thermal system, the secondary side of the central thermal unit being supplied with a second thermal fluid by a heat exchanger pump system; a branch of the thermal fluid circuit passing through the central thermal unit; a bypass of the thermal fluid circuit bypassing the central thermal unit; a three-way valve controlling the flow rate through the branch and the flow rate through the bypass; a temperature sensor measuring a flow temperature downstream from the branch and the bypass; and a controller controlling the pump system of the heat exchanger in response to a signal from the temperature sensor. In this embodiment, the central thermal unit can provide a lower or higher temperature thermal liquid depending on whether the thermal system is a cooling system or a heating system, and can adjust the amount of heat transferred in the heat exchanger by adjusting the energy supplied to the heat exchanger pumping system and thus the operating level of the heat exchanger pumping system, thereby adjusting the flow temperature in the thermal liquid circuit to approach the desired flow temperature in the thermal liquid circuit.

[0031] In a further embodiment, the controller is adapted to control said three-way valve in response to at least a signal from the temperature sensor, which makes it possible, for example, to reduce the amount of cooling or heating introduced into the thermal liquid circuit relative to the minimum amount that the central thermal unit can deliver.

[0032] In a second aspect, the object is achieved by a vessel comprising a thermal system according to the invention.

[0033] In a third aspect, a method of controlling a thermal system according to the invention as outlined above provides an invention, comprising circulating thermal liquid in a thermal liquid circuit by a pump system, obtaining a signal from a differential pressure sensor indicative of a differential pressure across a critical one of the pressure independent control valves, and adjusting the power of the pump system to obtain a signal from the differential pressure sensor within a desired range of values, thereby reducing energy losses.

[0034] In one embodiment, the thermal system comprises further differential pressure sensors adapted to sense respective differential pressures indicative of the differential pressure across the respective pressure independent control valves, and the method includes determining, for each of the differential pressure sensors, a required minimum value of the signal provided by the respective differential pressure sensor, and adjusting the power of the pump system in response to the signal of the one of the differential pressure sensors providing the lowest value signal relative to the respective required minimum value. In such an embodiment, the control device controlling the pump system may be adapted to use an indicated differential pressure that is closest to the required differential pressure of the respective pressure independent control valve as a basis for controlling the pump system. Thus, it is desirable for the control device to have information of differential pressure demands of a plurality of PICVs for which differential pressures are measured, calculated or indicated, compare the differential pressure demand with the measured, calculated or indicated differential pressure of the respective PICV to determine for which PICV the difference between the measured, calculated or indicated differential pressure and the differential pressure demand is the smallest, and use the differential pressure across that PICV as a basis for controlling the pump system.

[0035] In one embodiment, at least one first thermal consumer is arranged in series with a controllable pressure independent control valve, and a pressure and / or temperature sensor is attached to said first thermal consumer, and said method comprises obtaining a control signal from a pressure and / or temperature sensor and adjusting said controllable pressure independent control valve in dependence on said control signal from said pressure and / or temperature sensor. In such an embodiment, said temperature sensed by a sensor may be kept substantially constant or according to a given scheme.

[0036] In one embodiment, the thermal system comprises a central thermal unit; a branch of the thermal fluid circuit passing through the central thermal unit; a bypass of the thermal fluid circuit bypassing the central thermal unit; a three-way valve controlling the flow rate through the branch and the flow rate through the bypass; and a temperature sensor measuring the temperature of the flow downstream from the branch and the bypass, the method comprising obtaining a temperature signal from the temperature sensor and controlling the three-way valve in response to the temperature signal from the temperature sensor. The central thermal unit can provide a lower or higher temperature thermal fluid depending on whether the thermal system is a cooling or heating system, and the three-way valve allows the fluid from the central thermal unit to be mixed with the thermal fluid flowing through the thermal fluid circuit to obtain a desired flow temperature in the thermal fluid circuit.

[0037] In one embodiment, the thermal system comprises a central thermal unit comprising a heat exchanger having a primary side and a secondary side, the primary side being part of a thermal fluid circuit of the thermal system, the secondary side of the central thermal unit being supplied with a second thermal fluid by a heat exchanger pump system; a branch of the thermal fluid circuit passing through the central thermal unit; a bypass of the thermal fluid circuit bypassing the central thermal unit; a three-way valve controlling the flow rate through the branch and the flow rate through the bypass; and a temperature sensor measuring a flow temperature downstream from the branch and the bypass, the method comprising obtaining a temperature signal from the temperature sensor and controlling a heat exchanger in response to the temperature signal from the temperature sensor. In this embodiment, the central thermal unit can supply a lower or higher temperature thermal liquid depending on whether the thermal system is a cooling system or a heating system, and by adjusting the energy supplied to the heat exchanger pumping system and thereby the operating level of the heat exchanger pumping system, the amount of heat transferred in the heat exchanger can be adjusted so that the flow temperature of the thermal liquid circuit approaches the desired flow temperature in the thermal liquid circuit.

[0038] In a further aspect, the invention comprises a controller for a thermal system, the controller being adapted to carry out the method described above.

[0039] Embodiments and advantages described with reference to one aspect of the invention also apply to other aspects, unless specifically stated otherwise.

[0040] In the following the invention is explained in more detail by means of embodiment examples with reference to the following schematic drawings. [Brief description of the drawings]

[0041] [Figure 1] FIG. 1 is a schematic diagram of a cooling system according to the present invention. [Figure 1a] FIG. 1a shows an alternative embodiment of a cooling system according to the present invention. [Diagram 2] FIG. 2 shows the characteristics of PICV in the pressure / flow regime. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] FIG. 1 shows a thermal system, in particular a cooling system, installed on a vessel.

[0043] The system comprises a coolant circuit 10; a pump system 11 for circulating coolant in the coolant circuit 10, represented in this embodiment by a single pump symbol; a plurality of coolant consumers 20 arranged in parallel in the coolant circuit 10, said coolant consumers 20 being arranged in series with respective pressure independent control valves (PICVs) 30; and a control device 12 for controlling the pump system 11.

[0044] The system comprises a differential pressure sensor 13 adapted to sense a differential pressure indicative of the differential pressure across the critical one 30.1a of the pressure independent control valves 30.

[0045] In this embodiment, the coolant circulating in the coolant circuit 10 is ordinary fresh water to which an anti-rust agent or the like has been added.

[0046] In this embodiment, each of the cooling consumers 20 is placed in series with a pressure independent control valve 30 , so that the total flow of cooling liquid is controlled and balanced by the pressure independent control valve 30 .

[0047] A group of first cooling consumers 20.1 are each arranged in series with a controllable first pressure independent control valve 30.1. A pressure and / or temperature sensor 20.11 is respectively fitted to each first cooling consumer 20.1, providing a control signal for controlling the controllable first pressure independent control valve 30.1.

[0048] In this embodiment, the second cooling consumer 20.2 comprises further (two are shown in this example) small cooling consumers 20.2a arranged in parallel such that the small cooling consumers are arranged in series in common with the respective pressure-independent control valve 30.2.

[0049] In this embodiment, a group of third cooling consumers 20.3, each in series with a third pressure independent control valve 30.3, are placed in series with a fourth cooling consumer 20.3a, which has a lower demand for a lower cooling water temperature. The flow rate through the fourth cooling consumer 20.3a is therefore the sum of the combined flows through the third cooling consumers 20.3.

[0050] The cooling system further comprises a central cooling unit 40 .

[0051] A branch 10.1 of the coolant circuit passes through the central cooling unit 40 and a bypass 10.2 of the coolant circuit 10 bypasses the central cooling unit 40. A three-way valve 10.3 controls the flow rate through branch 10.1 and through bypass 10.2. A temperature sensor 10.4 measures the temperature downstream from branch 10.1 and bypass 10.2. A controller 10.5 is provided for controlling the three-way valve 10.3 in response to a signal from the temperature sensor 10.4.

[0052] The central cooling unit 40 supplies a cooler coolant compared to the coolant circulating in the coolant circuit 10, and in particular compared to the coolant entering the three-way valve 10.3, which allows the cooler coolant from the central cooling unit 40 to be mixed with the coolant flowing in the coolant circuit 10 so that the desired flow temperature in the coolant circuit 10 can be obtained as measured by the temperature sensor 10.4.

[0053] The central cooling unit 40 comprises a heat exchanger 40.1 with a primary side 40.1a and a secondary side. The primary side 40.1a is part of the coolant circuit 10 of the cooling system. The secondary side 40.1b of the central cooling unit 40 is supplied with a second thermal liquid by a heat exchanger pump system 40.2. In the illustrated embodiment, the second thermal liquid is seawater taken from the surrounding seawater in which the ship is sailing through a seawater intake 40.3, which is circulated by the heat exchanger pump system 40.2 through the secondary side 40.1b of the heat exchanger 40.1 and discharged to the surrounding seawater through a seawater outlet 40.4.

[0054] In one embodiment, a controller, for example the control device 12, is adapted to control the heat exchange pump system 40.2 in response to a signal from the temperature sensor 10.4.

[0055] In such an embodiment, the central cooling unit 40 can cool the entire amount of water circulating in the cooling liquid circuit by adjusting the three-way valve 10.3 to close the bypass 10.2 and pass all of the water through the heat exchanger 40.1. By adjusting the energy supplied to the heat exchanger pump system 40.2 and thereby adjusting the operation level of the heat exchanger pump system 40.2, the amount of heat transferred in the heat exchanger can be adjusted, thereby adjusting the thermal liquid circuit flow temperature, indicated by the temperature sensor 10.4, to approximate the desired flow temperature.

[0056] Furthermore, in such an embodiment, the control device 12 may be adapted to also control the three-way valve 10.3 or to activate the controller 10.5 in response to a signal from at least the temperature sensor 10.4, which makes it possible, for example, to reduce the amount of cooling introduced into the thermal liquid circuit 10 relative to the minimum amount that the central thermal unit 40 can deliver.

[0057] As indicated above, the cooling consumers 20 are each disposed in series with a pressure independent control valve 30 such that the flow rate of the cooling fluid within the cooling fluid circuit 10 is controlled and balanced by the pressure independent control valve 30 .

[0058] Each pressure independent control valve 30 requires a certain minimum differential pressure for control of the flow rate intended for the respective pressure independent control valve 30. This differential pressure is supplied throughout the coolant circuit 10 by the pump system 11.

[0059] In order to reduce the power supplied to the pumping system 11 to the minimum limit that ensures sufficient pressure differentials at all points in the coolant circuit 10, an indication of the pressure differential applied to the critical pressure independent control valve 30.1a is obtained by the differential pressure sensor 13 and the pumping system 11 is adjusted by the control device 12 according to said indication of the pressure differential applied to the critical pressure independent control valve 30.1a. This allows considerable energy savings to be achieved compared to a system in which the pumping system runs permanently at a given power.

[0060] In Fig. 1a an alternative embodiment is shown in which a further differential pressure sensor, as exemplified by differential pressure sensor 13a, is provided adapted to sense a respective differential pressure indicative of the differential pressure across each pressure independent control valve 30, and the control device 12 for controlling the pump system 11 is adapted to use the indicated differential pressure closest to the differential pressure required for the respective pressure independent control valve as the basis for controlling the pump system. In particular, it is foreseen that each pressure independent control valve 30 comprises or is fitted with a respective differential pressure sensor.

[0061] FIG. 2 illustrates how a substantially constant flow rate is provided by each pressure independent control valve 30 in the coolant circuit 10 (assuming that all pressure independent control valves 30 are intended to provide the same flow rate). min indicates the minimum differential pressure required by the critical pressure independent control valve 30.1a. The pump system 11 is operated at a pressure P indicated by the differential pressure sensor 13. c 2. Due to typical pressure losses in the coolant circuit 10, the lowest differential pressure exists in the vicinity of the critical pressure independent control valve 30.1a and throughout the remainder of the coolant circuit 10, as shown in FIG.syst As is well known to those skilled in the art, a differential pressure regulator at each pressure independent control valve 30 absorbs the excess pressure at each pressure independent control valve 30 to provide the desired flow rate as shown in FIG.

Claims

1. 1. A marine thermal system comprising: A thermal liquid circuit (10); a pump system (11) for circulating thermal liquid in the thermal liquid circuit (10); a plurality of thermal consumers (20) arranged in parallel in the thermal liquid circuit (10) and in series with respective pressure independent control valves (PICVs) (30); A control device (12) for controlling the pump system (11), a differential pressure sensor (13) adapted to sense a differential pressure indicative of a pressure difference across a critical one of said pressure independent control valves (30.1a), wherein a signal from said differential pressure sensor (13) is used by said control device (12) as a basis for controlling said pump system.

2. 2. The thermal system of claim 1, wherein the thermal liquid is water, preferably fresh water.

3. 3. The thermal system of claim 1 or 2, wherein each of a plurality of thermal consumers (20.1, 20.2, 20.3, 20.3a) is arranged in series with said pressure independent control valve (30.1, 30.1a, 30.2, 30.3), and the total flow rate of thermal liquid is controlled and balanced by said pressure independent control valve (30.1, 30.1a, 30.2, 30.3).

4. 3. A thermal system according to claim 1 or 2, wherein at least one first thermal consumer (20.1) is arranged in series with a controllable pressure-independent control valve (30.1, 30.1a), preferably a pressure sensor and / or a temperature sensor (20.11) is attached to the first thermal consumer (20.1) for providing a control signal for controlling the controllable pressure-independent control valve (30.1, 30.1a).

5. 3. The thermal system according to claim 1 or 2, wherein the second thermal consumer (20.2) comprises further small thermal consumers (20.2a, 20.2b) arranged in parallel and / or in series and arranged in common series with the respective second pressure-independent control valve (30.2).

6. 3. A thermal system as claimed in claim 1 or 2, wherein further differential pressure sensors (13, 13a) are provided adapted to sense respective differential pressures indicative of the differential pressure across each pressure independent control valve, and preferably the control device for controlling the pump system is adapted to use the indicated differential pressure closest to the differential pressure required across the respective pressure independent control valve as a basis for controlling the pump system.

7. A central thermal unit (40); a branch (10.1) of the thermal liquid circuit (10) passing through the central thermal unit (40); a bypass (10.2) of the thermal liquid circuit (10) which bypasses the central thermal unit (40); a three-way valve (10.3) for controlling the flow rate through said branch (10.1) and the flow rate through said bypass (10.2); a temperature sensor (10.4) for measuring the flow temperature downstream from said branch (10.1) and said bypass (10.2); 3. The thermal system of claim 1 or 2, further comprising a controller (10.5) for controlling the three-way valve (10.3) in response to a signal from the temperature sensor (10.4).

8. a central thermal unit (40) comprising a heat exchanger (40.1) with a primary side (40.1a) and a secondary side (40.1b), the primary side (40.1a) being part of the thermal liquid circuit (10) of the thermal system, the secondary side (40.1b) of the central thermal unit (40) being supplied with a second thermal liquid by a heat exchanger pump system (40.2); a branch (10.1) of the thermal liquid circuit (10) passing through the central thermal unit (40); a bypass (10.2) of the thermal liquid circuit (10) which bypasses the central thermal unit (40); a three-way valve (10.3) for controlling the flow rate through said branch (10.1) and the flow rate through said bypass (10.2); a temperature sensor (10.4) for measuring the flow temperature downstream from said branch (10.1) and said bypass (10.2); 3. The thermal system of claim 1 or 2, further comprising a controller (12) for controlling the heat exchanger pump system (40.2) in response to a signal from the temperature sensor (10.4).

9. 9. The thermal system of claim 8, wherein the controller (12) is also adapted to control the three-way valve (10.3) in response to a signal from at least the temperature sensor (10.4).

10. The thermal system of claim 1 or 2, wherein the thermal system is a cooling system.

11. The thermal system according to claim 1 or 2, wherein the thermal system is installed in a marine vessel.

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