Patent Description:
The cooling capacity of heat exchange systems having heat rejecting heat exchangers, with a variable temperature of coolant exiting the heat rejecting heat exchanger, is dependent on the temperature of the coolant exiting the heat rejecting heat exchanger and limited by the flow rate which can be achieved including the hydraulic losses incurred in the heat rejecting heat exchangers.

<CIT> discloses a temperature control system for a vehicle, comprising a main circuit, and first and second sub-circuits connected in parallel for cooling or heating of components connected thereto. In the main circuit and in the sub-circuits there are respective pumps.

According to a first aspect, there is provided a heat exchange system for providing cooling by circulating a coolant, the heat exchange system comprising:.

The load circuit or the supply circuit may comprise the valve arrangement. The expression "coolant from the supply circuit" is intended to refer to coolant provided to the mixing device from the coolant supply heat exchanger (i.e. without intervening circulation through the load circuit). The expression "recirculated coolant from the load circuit" is intended to refer to coolant provided from the cooling load heat exchanger without intervening circulation through the supply circuit.

The heat exchange system may be configured to operate with a supply recirculation condition in the mixing device, whereby at least a portion of coolant circulated by the supply pump follows a supply circuit recirculation loop extending through the mixing device. The heat exchange system may be configured to operate with a load recirculation condition in the mixing device, whereby at least a portion of coolant circulated by the load pump follows a load circuit recirculation loop extending through the mixing device.

It may be that the mixing device comprises: a supply circuit inlet for receiving chilled coolant from the supply circuit; a supply circuit outlet for providing coolant to the supply circuit for recirculation to the coolant supply heat exchanger; a load circuit inlet for receiving coolant from the load circuit; a load circuit outlet for providing coolant to the load circuit for heat transfer at the cooling load heat exchanger.

It may be that the heat exchange system is configured so that in use there is an equal flow rate of coolant through the supply circuit inlet and the supply circuit outlet (which may correspond to a minimum prevailing flow rate in the supply circuit). It may be that the heat exchange system is configured so that in use there is an equal flow rate of coolant through the load circuit inlet and the load circuit outlet (which may correspond to a minimum prevailing flow rate in the load circuit).

It may be that the mixing device is configured so that in use coolant drawn through the load circuit outlet preferentially originates from the supply circuit inlet, up to a flow rate of coolant flowing through the supply circuit inlet. It may be that the mixing device is configured so that in use coolant drawn through the supply circuit outlet preferentially originates from the load circuit inlet.

The mixing device may be configured so that in use coolant provided to the mixing device from the supply circuit inlet preferentially flows to the load circuit outlet, up to a flow rate of coolant through the load circuit outlet. The flow rate of coolant through the load circuit outlet may be defined as a minimum prevailing flow rate in the load circuit, Q<NUM>. The expression "minimum prevailing flow rate" is used as it should be appreciated that parts of the load circuit away from the load circuit outlet may have a higher flow rate, QL, for example owing to an additional recirculating flow within a sub portion of the respective circuit.

The mixing device may be configured so that in use coolant provided to the mixing device from the load circuit inlet preferentially flows to the supply circuit outlet, up to a flow rate of coolant through the supply circuit outlet. The flow rate of coolant through the supply circuit outlet may be defined as a minimum prevailing flow rate in the supply circuit, Q<NUM>.

It may be that the mixing device has a flow pathway between two opposing ends and is configured to permit flow in both directions along the flow pathway. It may be that a supply recirculation path from the supply circuit inlet to the supply circuit outlet is along a first direction along the flow pathway. It may be that a load recirculation path from the load circuit inlet to the load circuit outlet is along a second direction along the flow pathway. It may be that the supply recirculation path and the load recirculation flow path overlap along the flow pathway.

The heat exchange system may be configured to operate with a supply recirculation condition in the mixing device, whereby there is a net positive flow along the supply recirculation path in the mixing device. The heat exchange system may be configured to operate with a load recirculation condition in the mixing device, whereby there is a net positive flow along the load recirculation path in the mixing device.

It may be that the mixing device has a flow pathway between two opposing ends, wherein the supply circuit inlet and the load circuit outlet are relatively closer to a first end. It may be that the supply circuit outlet and the load circuit inlet are relatively closer to the opposing second end.

It may be that the mixing device has a bidirectional portion for flow of coolant in either direction, and wherein the mixing device is configured so that a flow rate and flow direction along the bidirectional portion corresponds to a difference between a minimum prevailing flow rate in the supply circuit and a minimum prevailing flow rate in the load circuit.

It may be that the mixing device is in the form of a tube.

It may be that the mixing device is generally elongate along the flow pathway. It may be that the inside diameter of the tube is at least <NUM> times larger than the largest diameter of the supply circuit inlet, the supply circuit outlet, the load circuit inlet and the load circuit outlet. It may be that the inside diameter of the tube is at least two times larger than the largest diameter of the supply circuit inlet, the supply circuit outlet, the load circuit inlet and the load circuit outlet, particularly when there are no space restrictions. This minimizes the pressure drop across the mixing device so that the supply circuit and the load circuit flow rates can be controlled independently of one another.

It may be that the load circuit comprises a bypass line for recirculation of coolant within the load circuit without passing through the mixing device.

It may be that the load circuit comprises a recirculation loop including the load pump, the cooling load heat exchanger and the bypass line, and excluding the mixing device.

It may be that the valve arrangement is configured to control the mix of coolant provided to the cooling load heat exchanger by controlling a split of flow received from the cooling load heat exchanger to (a) the bypass line and (b) the mixing device via a return line of the load circuit.

It may be that the heat exchange system is configured to operate in an high load flow condition in which a flow rate of the coolant flow provided to the cooling load heat exchanger is greater than a flow rate of coolant provided from the supply circuit to the mixing device, and in a low load flow condition in which the flow rate of the coolant flow provided to the cooling load heat exchanger is less than the flow rate of coolant provided from the supply circuit to the mixing device.

It may be that the valve arrangement is configured to operate in a partial bypass mode in which the coolant flow provided to the cooling load heat exchanger comprises a mix of (i) coolant from the supply circuit received via the mixing device and (ii) recirculated coolant from the load circuit via the bypass line. It may be that the valve arrangement is configured to operate in a full bypass mode in which the coolant flow provided to the cooling load heat exchanger consists of recirculated coolant from the load circuit. It may be that the valve arrangement is configured to operate in a full return mode in which the coolant flow provided to the cooling load heat exchanger consists of coolant received from the mixing device.

It may be that, in the partial bypass mode coolant flow provided to the cooling load heat exchanger comprises a mix of (i) coolant from the supply circuit received via the mixing device, (ii) recirculated coolant from the load circuit received via the bypass line and (iii) recirculated coolant from the load circuit received via the mixing device.

It may be that the heat exchanger is configured so that, when operating in the full return mode: there is a supply recirculation condition in the mixing device when a flow rate through the load pump is less than a flow rate of coolant provided to the mixing device from the supply circuit; and there is a load recirculation condition in the mixing device when a flow rate through the load pump is greater than a flow rate of coolant provided to the mixing device from the supply circuit.

It may be that the valve arrangement comprises a three-way valve configured to control a split of flow received from the cooling load heat exchanger to (i) the bypass line and (ii) the mixing device.

It may be that the heat exchange system comprises a controller configured to control the valve arrangement and/or the load pump to meet a cooling demand of the cooling load heat exchanger.

The controller may be configured to meet the cooling demand by controlling the valve arrangement and/or the load pump so that a monitored thermodynamic parameter associated with the load circuit or a heat source associated with the cooling load heat exchanger meets a primary target.

The primary target may be a value or range. The primary target may be a target temperature at a monitoring location associated with a heat source of the cooling load heat exchanger. The primary target may be a temperature (e.g. a set point temperature) of the heat source, for example a temperature of a component or a temperature-controlled environment or a process fluid to be cooled by the cooling load heat exchanger. The primary target may be a discharge temperature of the coolant flow through the cooling load heat exchanger (i.e. a temperature upon discharge of the coolant flow from the cooling load heat exchanger).

It may be that heat transfer at the cooling load heat exchanger is a function of a flow rate of the coolant flow provided to the cooling load heat exchanger and a temperature of the coolant flow provided to the cooling load heat exchanger. It may be that the controller is configured to control the valve arrangement and/or the load pump to meet a primary target associated with heat transfer at the cooling load heat exchanger meeting a cooling demand of the cooling load heat exchanger. It may be that the controller is configured to control the valve arrangement and/or the load pump to meet an auxiliary target associated with a property of the coolant flow provided to the heat exchanger. It may be that the controller is configured to control both the valve arrangement and the load pump to meet the primary target and the auxiliary target.

As the heat transfer at the cooling load heat exchanger is a function of a flow rate of the coolant flow provided to the cooling load heat exchanger and a temperature of the coolant flow provided to the cooling load heat exchanger, it may that there is a plurality of combinations of control settings for the load pump and the valve arrangement that would provide sufficient heat transfer to meet the cooling demand.

It may be that the controller comprises independent controllers for controlling the valve arrangement and the load pump respectively. For example, it may be that one of the controllers controls the load pump to meet the primary target, and the other of the controllers controls the valve arrangement to meet the auxiliary target.

It may be that the auxiliary target is defined to prevent excessive cooling at an upstream portion of the cooling load heat exchanger and/or excessive cooling of a component or portion of a component associated with an upstream portion of the cooling load heat exchanger.

It may be that the auxiliary target is a target temperature of the coolant flow provided to the cooling load heat exchanger.

The target temperature may be a minimum temperature, a temperature range between a minimum and maximum threshold, or a set-point. The temperature of the coolant flow provided to the cooling load heat exchanger is intended to refer to the temperature of the coolant flow at an inlet of the cooling load heat exchanger (i.e. as it is provided to the heat exchanger).

It may be that the heat exchange system comprises a cooling branch in the supply circuit in parallel and bypassing the mixing device, the cooling branch comprising a further cooling load heat exchanger.

It may be that the supply circuit is configured so that there is a branch point for providing flow into the cooling branch, wherein the branch point is upstream of the mixing device, and wherein there is a flow restriction device between the branch point and the mixing device configured so that a portion of flow circulating in the supply circuit flows through the cooling branch in preference to the mixing device.

It may be that the supply pump is a positive-displacement pump. It may be that the load pump is a positive-displacement pump.

According to a second aspect, there is provided a method of operating a heat exchange system in accordance with any preceding claim, comprising:.

It may be that, in response to an increase in a cooling demand at the cooling load heat exchanger from a baseline operating state of the heat exchanger:.

It may be that the valve arrangement prevents a reduction of the temperature of the coolant flow provided to the cooling load heat exchanger by controlling a setting of the valve arrangement to maintain or reduce a proportion (i) coolant from the supply circuit in the mix of the coolant flow provided to the cooling load heat exchanger.

It may be that, in response to a decrease in a cooling demand at the cooling load heat exchanger from a baseline operating state of the heat exchanger:.

It may be that in the baseline operating state, the temperature of the coolant flow provided to the cooling load heat exchanger corresponds to a target or limit temperature to prevent excessive cooling at an upstream portion of the cooling load heat exchanger and/or excessive cooling of a component or portion of a component associated with an upstream portion of the cooling load heat exchanger. Accordingly, it may be that the control of the valve arrangement to prevent a reduction of the temperature of the coolant flow is to prevent the variation of the flow rate through the cooling load heat exchanger from causing the temperature to fall below the target or limit temperature.

It may be that the method comprises selectively controlling the valve arrangement to operate in: a partial bypass mode in which the coolant flow provided to the cooling load heat exchanger comprises a mix of (i) coolant from the supply circuit received via the mixing device and (ii) recirculated coolant from the load circuit via the bypass line.

It may be that the method comprises controlling the valve arrangement in the partial bypass mode to vary a split of flow received from the cooling load heat exchanger to (a) the bypass line and (b) the mixing device via the return line, to vary a proportion of coolant from the supply circuit in the coolant flow provided to the cooling load heat exchanger.

It may be that the method further comprises selectively controlling the valve arrangement to operate in:.

It may be that the method comprises: operating the heat exchange system so that there is a supply recirculation condition in the mixing device, whereby at least a portion of coolant circulated by the supply pump follows a supply circuit recirculation loop extending through the mixing device. It may be that the method comprises operating the heat exchange system so that there is a load recirculation condition in the mixing device, whereby at least a portion of coolant circulated by the load pump follows a load circulation recirculation loop extending through the mixing device.

Embodiments will now be described, by way of example only, with reference to the accompanying Figures, in which:.

<FIG> shows a heat exchange system <NUM> for providing cooling to a load such as a car battery, by circulating coolant. The heat exchange system <NUM> comprises a supply circuit <NUM> for circulating the coolant, and a load circuit <NUM> for circulating the coolant. The heat exchange system <NUM> further comprises a mixing device <NUM> which is configured to form part of each of the supply circuit <NUM> and the load circuit <NUM>. In other words, the supply circuit <NUM> and the load circuit <NUM> are joined by the mixing device <NUM>.

The supply circuit <NUM> comprises a coolant supply heat exchanger <NUM> for rejecting heat from the coolant. Therefore, the output of the coolant supply heat exchanger <NUM> is configured to provide a supply of chilled coolant. The coolant supply heat exchanger <NUM> may be, for example, an evaporator of a refrigeration circuit.

The supply circuit <NUM> further comprises a supply pump <NUM> for circulating the coolant in the supply circuit <NUM>. The supply circuit <NUM> also comprises an expansion tank <NUM> which has fluidic connections respectively upstream and downstream of the coolant supply heat exchanger <NUM>, so that the expansion tank <NUM> is arranged in parallel with the coolant supply heat exchanger <NUM>. One of the fluidic connections of the expansion tank <NUM> is disposed between the supply pump <NUM> and the coolant supply heat exchanger <NUM>. The expansion tank <NUM> is configured to accommodate variable expansion due to temperature changes of the coolant in the supply circuit <NUM>, and to bleed air from the system <NUM>.

In this example, the mixing device <NUM> comprises a supply circuit inlet <NUM> for receiving chilled coolant from the supply circuit <NUM>, and a supply circuit outlet <NUM> for providing coolant to the supply circuit <NUM> for recirculation to the coolant supply heat exchanger <NUM>. The expression "coolant from the supply circuit" is intended to refer to coolant provided to the mixing device <NUM> from the coolant supply heat exchanger <NUM> (i.e., without intervening circulation through the load circuit <NUM>). The flow rate of coolant through the supply circuit outlet <NUM> is defined as a minimum prevailing flow rate in the supply circuit, Q<NUM>. The flow rate of coolant through the supply circuit outlet <NUM> is the same as the flow rate of coolant through the supply circuit inlet <NUM>.

The load circuit <NUM> comprises a cooling load heat exchanger <NUM> configured to transfer heat to the coolant from a heat source (or load) which requires cooling, and a load pump <NUM> for circulating the coolant in the load circuit <NUM>.

The load circuit <NUM> further comprises a valve arrangement <NUM> which is configured to control a mix of coolant from the supply circuit <NUM> and recirculated coolant from the load circuit <NUM>, in the coolant flow provided to the cooling load heat exchanger <NUM>.

In this example, the mixing device <NUM> comprises a load circuit inlet <NUM> for receiving coolant from the load circuit <NUM>, and a load circuit outlet <NUM> for providing coolant to the load circuit <NUM> for heat transfer at the cooling load heat exchanger <NUM>. The expression "coolant from the load circuit" or "recirculated coolant from the load circuit" is intended to refer to coolant provided from the cooling load heat exchanger <NUM> without intervening circulation through the supply circuit <NUM>. The flow rate of coolant through the load circuit outlet <NUM> is defined as the minimum prevailing flow rate in the load circuit <NUM>, Q<NUM>. The flow rate of coolant through the load circuit inlet <NUM> is the same as the flow rate of coolant through the load circuit outlet <NUM>, Q<NUM>.

In this example, the mixing device <NUM> has a flow pathway between two opposing ends and is configured to permit flow in both directions along the flow pathway. In this example, the supply circuit inlet <NUM> and the load circuit outlet <NUM> are relatively closer to a first end of the mixing device <NUM>, and the supply circuit outlet <NUM> and the load circuit inlet <NUM> are relatively closer to a second end of the mixing device <NUM>, opposing the first end. In other examples, the inlets and outlets may be at any suitable locations on the mixing device.

In this example, a supply recirculation path <NUM> from the supply circuit inlet <NUM> to the supply circuit outlet <NUM> is along a first direction along the flow pathway. A load recirculation path <NUM> from the load circuit inlet <NUM> to the load circuit outlet <NUM> is along a second direction along the flow pathway, opposing the first direction. In this example, the supply recirculation path <NUM> and the load recirculation path <NUM> overlap along the flow pathway. This ensures that coolant drawn through the load circuit outlet <NUM> preferentially originates from the supply circuit inlet <NUM>, up to a flow rate of coolant flowing through the supply circuit inlet <NUM>, and coolant drawn through the supply circuit outlet <NUM> preferentially originates from the load circuit inlet <NUM>, up to a flow rate of coolant flowing through the load circuit inlet <NUM>. In other words, it ensures that coolant provided to the mixing device <NUM> from the supply circuit inlet <NUM> preferentially flows to the load circuit outlet <NUM>, and coolant provided to the mixing device <NUM> from the load circuit inlet <NUM> preferentially flows to the supply circuit outlet <NUM>.

In some examples, the mixing device may have any suitable configuration so that in use, coolant drawn through the load circuit outlet preferentially originates from the supply circuit inlet, up to a flow rate of coolant flowing through the supply circuit inlet and coolant drawn through the supply circuit outlet preferentially originates from the load circuit inlet. In other examples, the mixing device may have any suitable configuration which does not have this preferential flow arrangement.

In this example, the mixing device <NUM> is in the form of a tube. In other examples, the mixing device may be any suitable shape, such as a tank or accumulator. In some examples, the mixing device may be generally elongate along the flow pathway. In the form of a tube, the mixing device is relatively small and lightweight, and allows for rapid temperature change responses of the coolant delivered to the cooling load heat exchanger <NUM> when the valve arrangement <NUM> modifies the mix of coolant to the cooling load heat exchanger <NUM>.

The mixing device <NUM> in the form of a tube has a low pressure drop between inlets <NUM>, <NUM>, and outlets <NUM>, <NUM>, which ensures that flow changes to the load circuit <NUM> will not affect flow in the supply circuit <NUM> and vice versa, thereby ensuring that the flow rates in the supply circuit <NUM> and the load circuit <NUM> can be independently controlled. In this example, the inside diameter of the tube of the mixing device <NUM> is at least <NUM> times larger than the largest inside diameter of the inlets <NUM>, <NUM> and outlets <NUM>, <NUM> of the mixing device <NUM>. In other examples, the inside diameter of the tube of the mixing device <NUM> is at least two times larger than the largest inside diameter of the inlets <NUM>, <NUM> and outlets <NUM>, <NUM> of the mixing device <NUM>. This ensures that the pressure drop across the mixing device <NUM> is low in comparison to the pressure drop in the supply circuit <NUM> and the load circuit <NUM>.

In this example, the load circuit <NUM> further comprises a bypass line <NUM> for recirculating coolant within the load circuit <NUM> without passing through the mixing device <NUM>. Therefore, in this example, the load circuit <NUM> comprises a bypass recirculation loop <NUM> including the load pump <NUM>, the cooling load heat exchanger <NUM> and the bypass line <NUM>, and excluding the mixing device <NUM>. Parts of the load circuit <NUM> away from the load circuit outlet <NUM>, such as in the bypass recirculation loop <NUM>, may have a higher flow rate, QL, than the minimum prevailing flow rate, Q<NUM>.

In this example, the valve arrangement <NUM> comprises a three-way valve <NUM> configured to control a split of flow received from the cooling load heat exchanger <NUM> to the bypass line <NUM> and to the mixing device <NUM> via a return line <NUM>. In other examples, there may be any suitable valve arrangement configured to control the mix of coolant provided to the cooling load heat exchanger <NUM>, for example, by controlling a split of flow received from the cooling load heat exchanger <NUM> to the bypass line <NUM> and to the mixing device <NUM> via the return line <NUM> of the load circuit <NUM>.

In this example, the three-way valve <NUM> is disposed in the load circuit <NUM> upstream of the mixing device <NUM>. In some examples, the three-way valve may be disposed downstream of the mixing device <NUM>, and upstream of the load pump <NUM> (i.e., between the mixing device <NUM> and the load pump <NUM>). In other examples, the three-way valve, or any suitable valve arrangement, may be disposed in the supply circuit <NUM> and may be configured to control a mix of coolant from the supply circuit and recirculated coolant from the load circuit, in a coolant flow provided to the cooling load heat exchanger.

The heat exchange system <NUM> further comprises a controller <NUM> which, in this example is configured to control the valve arrangement <NUM> and the load pump <NUM> to meet a cooling demand of the cooling load heat exchanger <NUM>. In other examples, there may be multiple controllers which control the valve arrangement <NUM> and the load pump <NUM>. In further examples, only one of the valve arrangement <NUM> and load pump <NUM> may be controlled.

In use, a load which is being cooled by the heat exchange system <NUM> may need to be cooled to a target temperature. The supply pump <NUM> is configured to pump coolant through the supply circuit <NUM>, and the load pump <NUM> is configured to pump coolant through the load circuit <NUM>. The load rejects heat to the cooling load heat exchanger <NUM>, thereby heating the coolant, and the heated coolant is recirculated, with some chilled coolant being introduced from the supply circuit <NUM> via the mixing device <NUM>, to chill the heated coolant.

In this example, in use, the heat exchange system <NUM> is configured to operate with a supply recirculation condition <NUM> in the mixing device <NUM>, whereby at least a portion of coolant circulated by the supply pump <NUM> follows a supply circuit <NUM> recirculation loop extending through the mixing device <NUM> and whereby there is a net positive flow along the supply recirculation path <NUM> in the mixing device <NUM>. The heat exchange system <NUM> in this example is also configured to operate with a load recirculation condition in the mixing device <NUM>, whereby at least a portion of coolant circulated by the load pump <NUM> follows a load circuit recirculation loop extending through the mixing device <NUM>, and whereby there is a net positive flow along the load recirculation path <NUM> in the mixing device <NUM>.

In this example, the valve arrangement <NUM> is configured to operate in one of three different modes: a partial bypass mode, a full bypass mode and a full return mode. In the partial bypass mode, the coolant flow provided to the cooling load heat exchanger <NUM> comprises a mix of coolant from the supply circuit <NUM> received via the mixing device <NUM>, recirculated coolant from the load circuit <NUM> received via the mixing device <NUM>, and recirculated coolant from the load circuit <NUM> via the bypass line <NUM>. In the full bypass mode, the coolant flow provided to the cooling load heat exchanger <NUM> consists solely of recirculated coolant from the load circuit <NUM>, via the bypass line <NUM>. In the full return mode, the coolant flow provided to the cooling load heat exchanger <NUM> consists solely of coolant received from the mixing device <NUM>, including coolant from the supply circuit <NUM> and recirculated coolant from the load circuit <NUM> through the mixing device <NUM>, such that there is no flow through the bypass line <NUM>.

In the full return mode, there is a supply recirculation condition <NUM> in the mixing device <NUM> when the flow rate of coolant through the load pump, QL = Q<NUM>, is less than the flow rate of coolant provided to the mixing device <NUM> from the supply circuit <NUM>, Q<NUM> (i.e., when Q<NUM> < Q<NUM>). In the full return mode, there is a load recirculation condition <NUM> in the mixing device <NUM> when the flow rate of coolant through the load pump, QL = Q<NUM>, is greater than the flow rate of coolant provided to the mixing device <NUM> from the supply circuit <NUM>, Q<NUM> (i.e., Q<NUM> > Q<NUM>). This difference in flow rate is enabled by the mixing device <NUM>.

The mixing device <NUM> therefore has a bidirectional portion for flow of coolant in either direction, and the flow rate and net flow direction, QM, along the bidirectional portion corresponds to a difference between the minimum prevailing flow rate in the supply circuit <NUM>, Q<NUM>, and the minimum prevailing flow rate in the load circuit <NUM>, Q<NUM>, (i.e., QM = Q<NUM> - Q<NUM>).

When the flow rate of the coolant provided to the cooling load heat exchanger <NUM>, QL, is higher than the flow rate of coolant provided from the supply circuit <NUM> to the supply circuit inlet <NUM>, the heat exchange system <NUM> may be configured to operate in a high load flow condition. When the flow rate of the coolant provided to the cooling load heat exchanger <NUM>, QL, is lower than the flow rate of coolant provided from the supply circuit <NUM> to the supply circuit inlet <NUM>, the heat exchange system <NUM> may be configured to operate in a low load flow condition.

Due to the mixing device <NUM> and valve arrangement <NUM>, the flow rate of coolant through the cooling load heat exchanger <NUM>, QL, can be controlled independently of the flow rate of coolant through the coolant supply heat exchanger <NUM>, QS = Q<NUM>. This minimises the effects of hydraulic resistance from the coolant supply heat exchanger <NUM> on the cooling capacity of the cooling load heat exchanger <NUM>, such that higher flow rates through the cooling load heat exchanger <NUM>, QL, can be achieved.

Being able to independently control the coolant flow rate in the cooling load heat exchanger <NUM>, QL, is particularly advantageous when the temperature of the chilled coolant provided to the mixing device <NUM> at the supply circuit inlet <NUM> is variable. Heat transfer at the cooling load heat exchanger <NUM> is a function of a flow rate of the coolant flow provided to the cooling load heat exchanger <NUM>, QL, and a temperature of the coolant flow provided to the cooling load heat exchanger <NUM>. When the coolant is too cold, a part of the load which rejects heat to an inlet of the cooling load heat exchanger <NUM> will reject more heat (and therefore be colder) than a part of the load which rejects heat to an outlet of the cooling load heat exchanger <NUM>. If the whole load must be cooled to the target temperature, then the part of the load at the inlet of the cooling load heat exchanger <NUM> will be much colder than the target temperature which can be damaging to a load, such as a car battery. Being able to increase the flow rate of coolant through the cooling load heat exchanger <NUM> independently, means that the temperature difference across the load can be reduced (so that more even cooling is achieved across the load). By increasing the flow through inlet of the cooling load exchanger <NUM> and decreasing the inlet flow temperature the difference between the coolant temperature at the inlet and outlet of the cooling load heat exchanger <NUM> is reduced, whilst preserving total cooling capacity is still preserved.

In this example, the controller <NUM> is configured meet the cooling demand of the cooling load heat exchanger <NUM> by controlling the valve arrangement <NUM> and the load pump <NUM> so that a monitored thermodynamic parameter associated with the load circuit <NUM> or a heat source (load) associated with the cooling load heat exchanger <NUM> meets a primary target associated with heat transfer at the cooling load heat exchanger <NUM>. The primary target may be a value or a range. It may be a temperature at a monitoring location associated with a heat source (load) of the cooling load heat exchanger <NUM>. The primary target may be a temperature (e.g., a set point temperature) of the heat source, for example a temperature of a component or a temperature-controlled environment or a process fluid to be cooled by the cooling load heat exchanger <NUM>. The primary target may be a discharge temperature of the coolant flow through the cooling load heat exchanger <NUM> (i.e., a temperature upon discharge of the coolant flow from the cooling load heat exchanger <NUM>). For example, the heat exchange system may comprise a sensor, such as a temperature or pressure sensor, for sensing a thermodynamic property of the coolant at the outlet of the cooling load heat exchanger <NUM> or a thermodynamic property of the load, and the sensor may output a reading to the controller <NUM>, which then controls the valve arrangement <NUM> and the load pump <NUM> to meet the primary target.

In this example, the controller <NUM> is also configured to meet an auxiliary target associated with a property of the coolant flow provided to the cooling load heat exchanger. For example, the auxiliary target may be a target temperature of the coolant flow provided to the cooling load heat exchanger <NUM>. For example, the heat exchange system may comprise a sensor, such as a temperature or pressure sensor, for sensing a thermodynamic property of the coolant at the inlet of the cooling load heat exchanger <NUM> or a thermodynamic property of the load at the inlet of the cooling load heat exchanger <NUM>, and the sensor may output a reading to the controller <NUM>, which then controls the valve arrangement <NUM> and the load pump <NUM> to also meet the auxiliary target.

The auxiliary target may be defined to prevent excessive cooling at the inlet or an upstream portion of the cooling load heat exchanger <NUM>. It may be defined to prevent excessive cooling of a component or portion of a component associated with an upstream portion of the cooling load heat exchanger <NUM>. The target temperature may be a minimum temperature, a set-point temperature or a set range between a maximum threshold and minimum threshold.

As the heat transfer at the cooling load heat exchanger <NUM> is a function of a flow rate of the coolant flow provided to the cooling load heat exchanger <NUM>, QL, and a temperature of the coolant flow provided to the cooling load heat exchanger <NUM>, there may be a plurality of combinations of control settings for the load pump <NUM> and the valve arrangement <NUM> that would provide sufficient heat transfer to meet the cooling demand. This may be achieved with a single controller <NUM> or a more than one controller. For example, with more than one controller, one of the controllers may control the load pump <NUM> to meet the primary target, and the other of the controllers may control the valve arrangement <NUM> to meet the auxiliary target.

<FIG> shows a second example heat exchange system <NUM> which is substantially similar to the first example heat exchange system <NUM> with like reference numerals denoting like parts. The second example heat exchange system <NUM> differs from the first example heat exchange system <NUM> in that it comprises a cooling branch <NUM> in the supply circuit <NUM> which branches from the line between the supply pump <NUM> and the supply circuit inlet <NUM> of the mixing device <NUM> at a branch point <NUM> (i.e., the branch point <NUM> is upstream of the mixing device <NUM>), and returns to a line in the supply circuit <NUM> between the coolant supply heat exchanger <NUM> and the supply circuit outlet <NUM> of the mixing device <NUM> (i.e., downstream of the mixing device <NUM>). The cooling branch <NUM> is therefore in parallel with, and bypassing, the mixing device <NUM>. In this example, the cooling load heat exchanger <NUM> in the load circuit <NUM> is a first cooling load heat exchanger <NUM>, and the cooling branch <NUM> comprises a second cooling load heat exchanger <NUM>, in the supply circuit <NUM>.

In this example, there is a flow restriction device <NUM> between the branch point <NUM> and the mixing device <NUM> (i.e., between the branch point <NUM> and the supply circuit inlet <NUM>) configured so that a portion of the flow circulating in the supply circuit <NUM> flows through the cooling branch <NUM> and the rest to the mixing device <NUM>. A second valve arrangement <NUM> is configured to control flow through the cooling branch <NUM>, and is controlled by the controller <NUM>.

Due to the separation of the supply circuit <NUM> and the load circuit <NUM>, as well as the mixing device <NUM> and the valve arrangements <NUM>, <NUM>, the flow rate of coolant through the first cooling load heat exchanger <NUM>, QL, can be controlled independently of the flow rate of coolant through the second cooling load heat exchanger <NUM>, Q<NUM>, so that each load or heat source can be cooled independently, as required. The supply circuit <NUM> may also comprise sensors at the second cooling load heat exchanger <NUM> similar to the sensors at the first cooling load heat exchanger <NUM>.

<FIG> is a flow chart showing steps of a method <NUM> of controlling a heat exchange system, such as the first example heat exchange system <NUM> or the second example heat exchange system <NUM>.

In block <NUM>, the method <NUM> comprises operating the supply pump <NUM> to circulate coolant through the coolant supply heat exchanger <NUM> and to provide coolant to the mixing device <NUM> at a supply flow rate, QS which may be equal to Q<NUM>.

In block <NUM>, the method <NUM> comprises determining a cooling demand at the cooling load heat exchanger <NUM>, <NUM>. The cooling demand may be from a baseline operating state of the respective cooling load heat exchanger <NUM>, <NUM>. The baseline operating state may be the temperature of the coolant flow provided to the cooling load heat exchanger <NUM> corresponding to a target or limit temperature to prevent excessive cooling at an upstream portion of the cooling load heat exchanger <NUM> and/or excessive cooling of a component or portion of a component associated with an upstream portion of the cooling load heat exchanger <NUM>.

Determining a cooling demand at the cooling load heat exchanger may comprise, for example, determining a thermodynamic property associated with the heat source (load) heat source which is cooled by the cooling load heat exchanger, such as the temperature of the heat source or the temperature of the coolant at an outlet of the cooling load heat exchanger <NUM>, <NUM>.

In block <NUM>, the method <NUM> comprises operating the load pump <NUM> to circulate coolant through the cooling load heat exchanger <NUM> at a cooling flow rate, QL.

In block <NUM>, the method <NUM> comprises controlling the valve arrangement <NUM> to vary the mix of cooling from the supply circuit <NUM> and recirculated coolant from the load circuit <NUM>, in a coolant flow provided to the cooling load heat exchanger <NUM>.

When the cooling load heat exchanger <NUM> is already at a baseline operating state (e.g., the coolant provided at the inlet of the cooling load heat exchanger <NUM> is already at a minimum or limit temperature), the valve arrangement <NUM> can be controlled to ensure that the temperature of the coolant does not reduce further, when the flow rate through the cooling load heat exchanger <NUM> is changed. Accordingly, the control of the valve arrangement <NUM> may be configured to prevent a reduction of the temperature of the coolant flow is to prevent the variation of the flow rate through the cooling load heat exchanger <NUM> from causing the temperature to fall below the target or limit temperature.

In this example, the valve arrangement <NUM> can be controlled to operate selectively in the partial bypass mode, the full bypass mode and/or the full return mode. In the partial bypass mode, the method <NUM> may comprise controlling the valve arrangement <NUM> to vary a split of flow received from the cooling load heat exchanger <NUM> to the bypass line <NUM> and the mixing device <NUM> via the return line <NUM>, to vary a proportion of coolant from the supply circuit <NUM> in the coolant flow provided to the cooling load heat exchanger <NUM>.

The method <NUM> may also comprise operating the heat exchange system <NUM>, <NUM> by controlling the valve arrangement <NUM> and the load pump <NUM> so that there is a supply recirculation condition in the mixing device <NUM> or operating the heat exchange system <NUM>, <NUM> by controlling the valve arrangement <NUM> and the load pump <NUM> so that there is a load recirculation condition in the mixing device <NUM>.

In an example in which the valve arrangement <NUM> is operating in a partial bypass mode, such that the heat exchange system <NUM>, <NUM> is operated in a supply recirculation condition, the proportion of flow through the bypass line <NUM> and the return line <NUM> affects the temperature of the coolant supplied to the cooling load heat exchanger <NUM>, without affecting the flow rate of the flow to the cooling load heat exchanger <NUM>, QL. When the valve arrangement <NUM> is operating in a partial bypass mode, such that the heat exchange system <NUM>, <NUM> is operated in a load recirculation condition, varying the proportion of flow through the bypass line <NUM> and the return line <NUM> has no effect on the temperature of the coolant provided to the cooling load heat exchanger <NUM>.

In this example, blocks <NUM> and <NUM> are based on the determined cooling demand. For example, in response to an increase in cooling demand at the cooling load heat exchanger <NUM> from a baseline operating state of the heat exchanger, the method <NUM> may comprise controlling the load pump <NUM> to increase a flow rate of the coolant flow provided to the cooling load heat exchanger, and may control the valve arrangement <NUM> to prevent a reduction of a temperature of the coolant flow provided to the cooling load heat exchanger <NUM>. In response to a decrease in cooling demand at the cooling load heat exchanger <NUM> from a baseline operating state of the heat exchanger, the method <NUM> may comprise controlling the load pump <NUM> to reduce a flow rate of the coolant flow provided to the cooling load heat exchanger, and may control the valve arrangement <NUM> to prevent a reduction of a temperature of the coolant flow provided to the cooling load heat exchanger <NUM>. In other examples, the control may be based on any suitable condition.

Claim 1:
A heat exchange system (<NUM>) for providing cooling by circulating a coolant, the heat exchange system comprising:
a supply circuit (<NUM>) for circulating the coolant comprising:
a coolant supply heat exchanger (<NUM>) for rejecting heat from the coolant to provide a supply of chilled coolant;
a supply pump (<NUM>) for circulating the coolant in the coolant supply circuit;
a load circuit (<NUM>) for circulating the coolant, comprising:
a cooling load heat exchanger (<NUM>) configured to transfer heat to the coolant;
a load pump (<NUM>) for circulating the coolant in the load circuit;
a mixing device (<NUM>) which is configured to form part of each of the supply circuit and the load circuit; and characterized by
a valve arrangement (<NUM>) configured to control a mix of (i) coolant from the supply circuit and (ii) recirculated coolant from the load circuit, in a coolant flow provided to the cooling load heat exchanger.