System and method for controlling the temperature of a rheometer or viscometer and system for measuring rheological properties

Abstract

Temperature control system (10) for a rheometer or a viscometer, wherein the temperature control system (10) comprises: a heating subunit (23) comprising at least one electrical resistance heating element (31); a Peltier element subunit (25) comprising at least one Peltier element (51); and a displacement system (27) arranged to bring the Peltier element subunit (25) into and out of contact with the heating subunit (23).

Description

[0001] The invention relates to methods and systems for temperature control, in particular to a temperature control system of a rheometer or viscometer. State of the art

[0002] Rheometers or viscometers are used to measure the rheological properties (such as viscosity profiles) of a sample. Since the rheological properties of a sample are often highly dependent on its temperature, it is important that a rheometer / viscometer has a precise temperature control mechanism. This allows the temperature dependence of the rheological properties to be measured and taken into account.

[0003] From DE 100 58 399 A1, for example, such a temperature control system for a rheometer or viscometer is known, with which the temperature of a sample can be adjusted and a temperature gradient within a sample can be minimized.

[0004] There are various temperature control mechanisms, such as electrical resistors, heat exchangers, and Peltier elements. However, these different systems have disadvantages. For example, a temperature control mechanism based on a Peltier element can control temperatures from -40 °C to 160 °C. However, temperature control mechanisms based on the Peltier element typically do not reach temperatures above 200 °C, and their performance deteriorates when heated to high temperatures. Therefore, there is room for improvement in this area. Brief description

[0005] According to a first aspect of the invention, a temperature control system for a rheometer or a viscometer is provided. The temperature control system comprises a heating subunit comprising at least one electrical resistance heating element, a Peltier element subunit comprising at least one Peltier element, and a displacement system arranged to move the Peltier element subunit into and out of contact with the heating subunit.

[0006] Furthermore, a system for measuring rheological properties of a sample is provided. The system comprises an actuator; a measuring device arranged to measure a force applied to the sample and a deformation of the sample; a rotor; a stator; and the temperature control system described above. The actuator is configured to move the rotor relative to the stator to deform the sample.

[0007] Further provided is a method for controlling the temperature of a sample for a rheometer or viscometer. The method comprises loading the sample into the rheometer or viscometer; adjusting a temperature of the sample with one or both of: a heating subunit comprising at least one electrical resistance heating element; and a Peltier element subunit including at least one Peltier element; and, in response to a temperature of the Peltier element subunit, operating a translation system to move the Peltier element subunit into and out of contact with the heating subunit. By utilizing the Peltier element subunit, the aforementioned temperature control system is capable of providing fine-tuning temperature control of the sample over a low temperature range, typically from -40°C to 160°C.Using the heating sub-unit, the temperature control system can provide temperature control of the sample over a high temperature range, typically above 160 °C and up to 400 °C. Using the sliding system ensures that the Peltier element sub-unit is out of contact with the heating sub-unit when heating the sample in the high temperature range, thus preventing deterioration of the Peltier element. Brief description of the drawings

[0008] For a better understanding of the invention and to show how it can be implemented, reference will now be made, by way of example only, to the accompanying drawings in which: Fig. 1 shows a schematic representation of a viscosity measuring device; Fig. 2 a measuring cell, comprising a temperature control system, of the viscosity measuring device of Fig. 1 according to the present invention, wherein the temperature control system is in a first position; Fig. 3 the measuring cell of Fig. 2 shows the measuring cell in the second position; Fig. 4 the measuring cell of Fig. 2 and shows a heat exchanger subsystem; Fig. 5 shows a flowchart illustrating a first method for operating the temperature control system of Fig. 2 describes; and Fig. 6 shows a flow chart illustrating a second method of operating the temperature control system of Fig. 2 describes. Detailed description

[0009] Fig. Figure 1 shows a schematic representation of a viscosity measuring device 1, such as a rheometer or a viscometer. Furthermore, a rheometer is used to measure the viscoelastic properties of a material, while a viscometer is more limited in its performance and is used to measure the viscosity of the material. Rheological properties define the way in which the viscoelasticity of a material changes depending on the applied shear stress and deformation. Generally, the viscosity measuring device 1 is used to measure the viscosity of a sample 2.

[0010] The viscosity measuring device 1 comprises a deformation actuator 201, a measuring device 202 and a measuring cell 3. In the illustrated embodiment, the deformation actuator 201 and the measuring device 202 are combined to form a measuring head 5.

[0011] The deformation actuator 201 is configured to exert a force or displacement on the sample 2. The deformation actuator 201 can be mechanically coupled to either a rotor or a stator. In use, the deformation actuator 201 exerts a shear stress and / or a shear deformation on the sample 2, causing it to deform. The deformation actuator 201 can provide a rotational force or torque. For example, the deformation actuator 201 can be a motor that exerts a torque or angular displacement, which can cause at least a portion of the sample 2 to rotate.

[0012] The measuring device 202 is configured to measure the force or torque and / or displacement, for example, an angular displacement exerted by the deformation actuator 201. The measuring device 202 may include one or more of a force sensor, a torque sensor, and a displacement / angle sensor. The force and / or displacement generated by the deformation actuator 201 correspond to the resulting shear stress and / or shear deformation of the sample 2, which further correspond to a geometrically controlled deformation of the sample 2. Both shear stress and shear deformation are the fundamental quantities used in the rheological equations for determining, for example, viscosity. The measuring device 202 may comprise a plurality of separate measuring devices that measure different parameters independently, but are collectively referred to as the measuring device 202.For example, one device may measure the force and / or torque exerted by the deformation actuator 201 via the magnitude of the electrical current, and a second device may measure the resulting deformation of the sample 2 via the magnitude of an angular deflection.

[0013] In the illustrated embodiment, the measuring head 5 is arranged to provide a movement, such as rotation, to the sample 2 via the measuring cell 3 and to measure the applied force and the resulting deformation. Therefore, the Measuring head 5 includes both the deformation actuator 201 and the measuring device 202. The measuring cell comprises a rotor 13 and a stator 15.

[0014] The viscosity measuring device 1 may further comprise a frame 7 and a lifting device 9. The frame 7, in combination with the lifting device 9, is provided to hold the measuring head 5 in position relative to the sample 2. The measuring head 5, which can control the rotor 13, can be held in a known and precise position to ensure a defined distance between the rotor 13 and the stator 15, so that a gap in which the sample is placed is precisely adjusted and can measure the exact deformation of the sample 2. The lifting device 9 allows the measuring head 5 with the rotor 13 to be raised and lowered relative to the stator 15, so that the gap for the sample 2 can be changed to accommodate different sample types and volumes. The lifting device 9 also enables the clamping of the sample 2.

[0015] The viscosity measuring device 1 further comprises a temperature control system 10 for controlling the sample temperature. In use, the sample 2 being analyzed is held between the rotor 13 and the stator 15, and the rotor 13 and the stator 15 are configured to hold and deform the sample 2 between them. The rotor 13 and the stator 15 can be configured to hold and deform the sample 2 in the defined gap between the rotor and the stator. Although the stator 15 and the temperature control system 10 in Fig. 1 are shown as separate parts, they may be formed integrally. For example, the stator 15 may be the upper surface of the temperature control system 10.

[0016] The rotor 13 is mechanically coupled to the deformation actuator 201 so that the deformation actuator 201 can move the rotor to deform the sample 2. In the illustrated embodiment, the rotor 13 is connected to the measuring head 5, which includes the actuator. The deformation actuator 201 is configured to move the rotor 13 relative to the stator 15. In other words, the rotor 13 is movable and the stator 15 is held stationary. The preferred movement for the rotor 13 is rotation, but additional types of movement are possible, such as vibration, which would also lead to deformation that could then be measured. In some embodiments, the position of the rotor 13 and the stator 15 can be swapped. That is, the stator 15 is positioned on top of the sample 2, and the rotor 13 is positioned below the sample 2.

[0017] In use, the sample 2 is held between the rotor 13 and the stator 15 and in direct contact with them. For example, a first surface of the sample 2 is held stationary relative to the rotor 13 and a second surface of the sample 2 is held stationary relative to the stator 15. The first sample surface is preferably opposite the second surface. The surfaces of the sample 2 may be held stationary relative to the rotor 13 and the stator 15 by friction / adhesion interfaces. Alternatively, the rotor 13 and the stator 15 may be bonded to the sample surfaces in some way. Holding the surfaces of the sample 2 stationary relative to the rotor 13 and the stator 15 results in the sample 2 being deformed as the rotor 13 moves relative to the stator 15.

[0018] Fig. 1 shows the temperature control system 10 coupled to the stator 15. In some embodiments, the temperature control system 10 may alternatively or additionally be coupled to the rotor 13. In one example, the temperature control system 10 disclosed herein may be part of a hood that is thermally coupled to the rotor 13.

[0019] It will Fig. 2 and Fig. 3, which shows the measuring cell 3 and the temperature control system 10 in more detail. The temperature control system 10 comprises a heating subunit 23, a Peltier element subunit 25, and a displacement system 27.

[0020] In the illustrated embodiment, in particular, a sample support surface 28 of the temperature control system 10 and the heating subunit 23 acts as the stator 15. The sample support surface 28 may also be referred to as the first surface 28 of the heating subunit 23. In other words, during use, the sample 2 is in contact with the sample support surface 28 of the temperature control system 10. Bringing the sample 2 into direct contact with the sample support surface 28 of the temperature control system 10 enables easier heat transfer between the temperature control system 10 and the sample 2. In some embodiments, an independent stator 15 may be present between the temperature control system 10 and the sample 2 to conduct heat therebetween. The independent stator 15 between the temperature control system 10 and the sample 2 may protect the temperature control system 10 from abrasion by the sample 2.

[0021] As shown in the illustrated embodiment, the temperature control system 10 may further include a housing 29 for supporting the heating sub-unit 23. The heating sub-unit 23 is held stationary relative to the housing 29. This is achieved by attaching the heating sub-unit 23 to the top of the housing 29 in the illustrated embodiment. The Peltier element sub-unit 25 and the translation system 27 may be encapsulated within the housing 29. The Peltier element sub-unit 25 is movable relative to the housing 29 by the translation system 27. This allows the translation system 27 to move the Peltier element sub-unit 25 relative to the heating sub-unit 23.

[0022] The temperature control system 10 also includes a controller 30 (in Fig. 1). The controller 30 includes a processor and a non-volatile memory for storing computer-readable instructions. By executing the computer-readable instructions with the processor, the controller 30 is arranged to control one or more of the heating subassembly 23, the Peltier element subassembly 25, the displacement system 27, and the deformation actuator 201, as described hereinafter. Additionally, the controller 30 is arranged to receive data from the temperature sensors 35, 55 as well as the measuring device 202 as control input. The controller 30 can use the data from the temperature sensors 35, 55 as feedback in controlling the temperature of the sample 2. Optionally, the controller 30 can be replaced or controlled by an external processing device (e.g., a laptop) 30', as shown via a wired or wireless connection for operating the temperature control system 10.

[0023] Referring more specifically to the components of temperature control system 10, heating subunit 23 includes an electrical resistance heating element 31, such as a wire, that heats when an electrical current is passed through it. Electrical resistance heating element 31 heats rapidly after exposure to electrical current and can provide temperatures up to and / or above 400°C. Optionally, heating subunit 23 may include a plurality of electrical resistance heating elements 31.

[0024] The heating subassembly 23 further includes a first thermally conductive material 33 that conducts heat from the electrical resistance heating element 31 to the sample 2. An upper surface of the first thermally conductive material 33 forms the sample support surface 28. Alternatively, the electrical resistance heating element 31 could be arranged on the surface of the heating subassembly 23 so that it directly provides heat to the sample 2. However, the first thermally conductive material 33 allows other components in addition to the heating subassembly 23 to directly influence the temperature of the sample 2. As illustrated, the first thermally conductive material 33 can completely surround the electrical resistance heating element 31, such that the upper and lower surfaces of the heating subassembly 23 are formed by the first thermally conductive material 33.

[0025] The heating sub-unit 23 preferably further comprises a heating temperature sensor 35 arranged to measure the temperature of at least a portion of the heating sub-unit 23, such as the first thermally conductive material 33 of the heating sub-unit 23. Preferably, the temperature sensor 35 may be embedded within the first thermally conductive material 33. The heating temperature sensor 35 may be located near the sample support surface 28 and thus the sample 2. In general, the heating temperature sensor 35 may be used to measure the temperature of sample 2. For example, the sample temperature can be measured by temperature sensor 35.

[0026] The heating subassembly 23 further includes a heater heat exchanger 37 for regulating the temperature of at least a portion of the heating subassembly 23, such as the first thermally conductive material 33. The heater heat exchanger 37 preferably includes a conduit 39 for conducting heat exchange fluid through the first thermally conductive material 33 and also includes a conduit valve 39' for regulating the flow of the heat exchange fluid through the conduit 39. The heat exchange fluid may be liquid or gaseous. As illustrated, the conduit 39 is positioned between the electrical resistance heating element 31 and the Peltier element subassembly 25. Alternatively, the conduit 39 could be disposed on the side of the heating subassembly 23 or between the electrical resistance heating element 31 and the sample support surface 28, as these positions would also allow the heater heat exchanger 37 to cool the first thermally conductive material 33.By positioning the line 39 between the electrical resistance heating element 31 and the sample support surface 28, the performance can be negatively affected unless gas is used as the heat exchange fluid.

[0027] As in Fig. As shown in Figure 4, line 39 is connected to an external heat exchanger 41 via heat exchange fluid tubes 43. The external heat exchanger 41 serves to regulate the temperature of the heat exchange fluid and thus of the first thermally conductive material 33. The heating heat exchanger 37 can be used to reduce the temperature of the sample 2 if it is desired to cool the sample 2. This is particularly important when the Peltier element subassembly 25 is not used to cool the sample.

[0028] The Peltier element subassembly 25 includes a Peltier element 51, which is an active solid-state heat pump capable of transferring heat from one side of the device to the other using electrical energy. Such an instrument is also referred to as a Peltier device, Peltier heat pump, solid-state refrigeration, or thermoelectric cooler (TEC). The Peltier element 51 operates via the Peltier effect. The direction in which the Peltier element 51 transfers heat depends on the direction of an electric current supplied to the Peltier element 51. The Peltier element 51 includes a sample side 51a for conducting heat to or from the sample 2 and a secondary side 51b for extracting or dissipating heat. Therefore, the Peltier element 51 can be used to heat or cool the sample 2.

[0029] In preferred examples of a cooling mode, wherein the temperature of the sample side 51a is lower than the temperature of the secondary side 51b, the Peltier element 51 can maintain a temperature difference between the sample side 51a and the secondary side 51b of more than 50°C. For example, if the secondary side 51b is maintained at 10°C, the sample side 51a can reach temperatures of -40°C. In preferred examples of a heating mode, wherein the temperature of the sample side 51a is higher than the temperature of the secondary side 51b (for example, assisted by internal heat dissipation), the Peltier element 51 can maintain a temperature difference between the sample side 51a and the secondary side 51b of more than 100°C. For example, if the secondary side 51b is maintained at 100°C, 200°C can be reached on the sample side 51a.Since the Peltier element 51 may experience performance degradation at temperatures close to 200 °C, the secondary side 51b can be maintained at 60 °C and the sample side 51a is therefore capable of reaching 160 °C.

[0030] Therefore, by controlling the temperature of the secondary side 51b within a range of 10°C to 60°C, precise control of the temperature of the sample side 51a can be achieved within a temperature range of typically -40°C to 160°C. Additionally, the Peltier element subunit 25 may include a plurality of Peltier elements 51.

[0031] The Peltier element subassembly 25 further includes a second thermally conductive material 53 that conducts heat from the Peltier element 51 to the sample 2, and the second thermally conductive material 53 is in contact with the sample side 51a of the Peltier element 51. The second thermally conductive material 53 of the Peltier element subassembly 25 is arranged to conduct heat from the sample side 51a of the Peltier element 51 to the first thermally conductive material 33 of the heating subassembly 23 when the two subassemblies 23, 25 are in contact. This enables heat transfer between the sample 2 and the Peltier element 51 via the first and second thermally conductive materials 53, 33, so that the Peltier element 51 can heat or cool the sample 2.

[0032] The Peltier element subassembly 25 further includes a Peltier element temperature sensor 55 arranged to measure the temperature of at least a portion of the Peltier element subassembly 25, such as the conductive material 55. The temperature sensor 55 may be embedded within the conductive material 53 and may be used to monitor the temperature of the Peltier element 51. This may be used to ensure that the Peltier element 51 is not heated above a temperature at which it degrades. In addition, the Peltier element temperature sensor 55 may be used to measure the temperature of the sample 2 to additionally provide further feedback to the heater temperature sensor 35.

[0033] The Peltier element temperature sensor 55 may also provide feedback, for example, to a control loop to maintain the Peltier element subassembly 25 at a standby temperature when it is out of contact with the heater subassembly 23. The standby temperature may be a maximum temperature at which the Peltier element 51 does not experience degradation.

[0034] The Peltier element subunit 25 further comprises a Peltier element heat exchanger 57. The Peltier element heat exchanger 57 preferably comprises a conduit 59 for conducting heat exchange fluid near the Peltier element 51 and preferably near the secondary side 51b of the Peltier element 51. As illustrated, the conduit 59 extends through a second conductor material that is in contact with the secondary side 51b of the Peltier element 51. As shown in Fig. As shown in Figure 4, line 59 may be connected to external heat exchanger 41. Peltier element heat exchanger 57 may be used to provide or absorb heat from the secondary side 51b of Peltier element 51. This assists Peltier element 51 in heating or cooling sample 2 as needed. Peltier element heat exchanger 57 also includes a line valve 59' for regulating the flow of heat exchange fluid through line 59.

[0035] The heater core 37, the Peltier element heat exchanger 57, and the external heat exchanger 41 can together form a heat exchanger subsystem. Furthermore, the line valves 39', 59' can be replaced by pumps, so that active flow control is used to provide temperature control across the heat exchanger subsystem. An alternative heat exchanger subsystem can be arranged to transfer excess heat to the ambient air using a finned heat exchanger and, optionally, a fan.

[0036] The translation system 27 is arranged to move the Peltier element subassembly 25 into and out of contact with the heating subassembly 23. In particular, the translation system 27 is arranged to move the Peltier element subassembly 25 into and out of contact with the first thermally conductive material 33 of the heating subassembly 23. This allows the heating subassembly 23 to heat the sample 2 to temperatures at which the Peltier element 51 would deteriorate, without damaging the Peltier element 51, since the Peltier element subassembly 25 can be out of contact with the heating subassembly 23 at these temperatures. The contact between the Peltier element subassembly 25 and the heating subassembly 23 includes any arrangement of fixed conductive bridges that allow thermal energy to be transferred from the heating subassembly 23 to the Peltier element subassembly 25 along a fixed conductive path.Therefore, the contact between the Peltier element subunit 25 and the heating subunit 23. can also be referred to as thermal coupling of the subunits 23, 25. For example, if the heating subunit 23 is in contact with the sample 2 and the Peltier element subunit 25 is also in contact with the sample 2, the heating subunit 23 can be referred to as being in contact with the Peltier element subunit 25, since heat can be transferred between the two even though there is no direct physical contact between the heating subunit 23 and the Peltier element subunit 25. In other words, the contact refers to a fixed conductive path that exists between the two subunits 23, 25. Conversely, if the Peltier element subunit 25 is out of contact with the heating subunit 23, the subunits are arranged so that no heat is conducted from the heating subunit 23 to the Peltier element subunit 25 via a fixed conductive path (or essentially no heat is transferred, i.e.heat transfer is negligible). This can also be referred to as thermal decoupling of the subunits 23, 25. The potential for heat transfer via the housing should be ignored, as this is negligible.

[0037] Alternatively, the translation system 27 may be arranged to move the Peltier element subassembly 25 into and out of direct contact with the heater subassembly 23. Direct contact may refer to physical contact between a portion of the Peltier element subassembly 25 and a portion of the heater subassembly 23.

[0038] The translation system 27 may be arranged to move the Peltier element sub-assembly 25 into and out of contact with the heating sub-assembly 23 based on at least one or more of: a temperature of the Peltier element sub-assembly 25; a temperature of the heating sub-assembly 23; and a temperature of the sample 2. The aforementioned temperature may be the current or target temperature of the sample 2.

[0039] In the illustrated embodiment, the subunits are arranged in series, meaning that the Peltier element subunit 25 is located below the heater subunit 23, and the sample support surface 28 is located on top of the heater subunit 23, i.e., opposite the side on which the Peltier element subunit 25 is located. In this embodiment, the translation system 27 raises the Peltier element subunit 25 so that it is in contact with the heater subunit 23 and lowers the Peltier element subunit 25 so that it is out of contact with the heater subunit 23.

[0040] In an alternative embodiment, the Peltier element sub-assembly 25 could be located on the side of the heating sub-assembly 23. The Peltier element sub-assembly 25 could then be brought into and out of contact with the heating sub-assembly 23 by horizontal movement. In this embodiment, the sample support surface 28 on top of the heating sub-assembly 23 would simply be on a different side than the one on which the Peltier element subunit 25 is located, but not on the opposite side. In other words, the sample support surface 28 on top of the heating subunit 23 is not the opposite side to which the Peltier element subunit 25 is located. In fact, any arrangement is possible in which the sample support surface 28 of the heating subunit 23 is arranged to be close to the sample 2 and a second surface of the heating subunit 23 is arranged to be in contact with the Peltier element subunit 25.

[0041] The displacement system 27 can displace the heater subassembly relative to the Peltier element subassembly by actuating a displacement actuator or by thermal expansion / dilation or contraction. The displacement actuator can include a motor, a pneumatic actuator, a magnetic actuator, or a piezo actuator. In an alternative embodiment, the displacement system 27 can generate displacement through thermal expansion or contraction, also referred to as thermal dilation, thereby enabling passive temperature-based control of the displacement system 27.

[0042] The displacement system 27 preferably comprises two base sections 71, 73 and an extendable displacement actuator 75 (in Fig. 3). A first base portion 71 engages the housing 29, while a second base portion 73 engages the Peltier element subassembly 25. The extendable displacement actuator 75 moves the second base portion 73 relative to the first base portion 71 and can therefore move the Peltier element subassembly 25 relative to the housing 29 and toward the heater subassembly 23.

[0043] The displacement system 27 moves a part of the temperature control system 10 between a Fig. 3 shown engaged position and a separated position (shown in Fig. 2), as described below. The engaged position may also be referred to as the first position, and the separated position may be referred to as a decoupled position.

[0044] As in Fig. 2, the Peltier element subunit 25 is not in contact with the heating subunit 23 in the separated position. As a result, a gap 60, preferably an air gap, exists between the Peltier element subunit 25 and the heating subunit 23. The gap 60 can have any value above 0 mm or above 0.1 mm. For example, the gap can be between 1 and 10 mm. In other words, the displacement system 27 is configured to separate the subunits 23, 25 so that a gap with any value above 0 mm (for example, between 1 and 10 mm) exists between the heating subunit 23 and the Peltier element subunit 25. Therefore, the second thermally conductive material 53 of the Peltier element subunit 25 is not in

[0045] Contact with the first thermally conductive material 33 of the heating sub-assembly 23, and no heat can be transferred from the electrical resistance heating element 31 to the Peltier element 51. This ensures that the Peltier element 51 is not damaged by high temperatures. In the separated position, the Peltier element sub-assembly 25 is unable to heat or cool the sample 2. Therefore, the controller 30 is configured to regulate the displacement system 27 to ensure that the Peltier element sub-assembly 25 is not in the separated position at low temperatures, with the Peltier element 51 providing better temperature control, as described below.

[0046] As in Fig. 3, in the engaged position, the Peltier element subassembly 25 is in contact with the heating subassembly 23. The translation system 27 is operated to move the Peltier element subassembly 25 such that the gap 60 is removed and the second thermally conductive material 53 of the Peltier element subassembly 25 is in contact with the first thermally conductive material 33 of the heating subassembly 23. This allows heat to be transferred from the sample 2 to and from the Peltier element 51 via the first and second thermally conductive materials 33, 53 of the two subassemblies 23, 25. In the engaged position, heat is also transferred from the electrical resistance heating element 31 to the Peltier element 51, which could cause deterioration or damage to the Peltier element 51 if the temperature of the electrical resistance heating element 31 or the sample 2 exceeds a certain temperature.Therefore, the controller 30 is designed to regulate the displacement system 27 to ensure that the Peltier element subassembly 25 is not in the engaged position at high temperatures, which could damage the Peltier element 51, as described below.

[0047] Although the illustrated embodiment shows the temperature control system 10 below and / or integrated into the stator 15, in an alternative embodiment, the above-described temperature control system 10 could be above and / or integrated into the rotor 13. All features of the previous embodiment would apply, except for the orientation of the subassemblies 23, 25.

[0048] A method for operating the temperature control system 10 will now be described. Generally, the method involves changing the temperature of the sample 2 and operating the translation system 27 based on the temperature of the sample 2.

[0049] The temperature of the sample 2 is changed using the Peltier element sub-unit 25 and / or the heating sub-unit 23. For example, the Peltier element 51 in the engaged position can be used to supply heat to the sample 2 via the first and second thermally conductive materials 33, 53 of the sub-units 23, 25. In this In this case, heat energy is supplied to the Peltier element 51 through the Peltier element heat exchanger 57. The Peltier element 51 can also be used to remove heat from the sample 2 (via the first and second thermally conductive materials 33, 53) to cool the sample 2. In this case, heat is transferred from the Peltier element 51 to the Peltier element heat exchanger 57.

[0050] The electrical resistance heating element 31 can also be used to supply heat to the sample 2 via the first thermally conductive material 33 of the heating subunit 23. The heating heat exchanger 37 can be used to remove heat from the sample 2 via the first thermally conductive material 33.

[0051] The translation system 27 is operated based on the temperature of the sample 2 (which is preferably monitored using the temperature sensors 35, 55) as follows. There is a threshold temperature above which there is an increased risk of deterioration of the Peltier element 51. The threshold temperature can be selected for a specific Peltier element 51, but is typically in the range of 150°C to 200°C, depending on the manufacturer's specifications of the Peltier element. A favorable threshold temperature may be in the range of 150°C to 160°C, since above this temperature range the Peltier elements lose performance in terms of heating rate. When the sample 2 is heated at temperatures above a first threshold temperature (e.g., a temperature in the range of 150°C to 160°C), the controller 30 operates the translation system 27 to place the temperature control system 10 in the disconnected position.This prevents the Peltier element 51 from deteriorating. When the sample 2 is heated or cooled at temperatures below a second threshold temperature (e.g., a temperature in the range of 130°C to 140°C), the controller 30 operates the translation system 27 to place the temperature control system 10 in the engaged position. This makes it possible to use finer control of the Peltier element 51 at temperatures below the second threshold temperature. The first threshold temperature can be higher than or equal to the second threshold temperature. By using different threshold temperatures for separating and engaging the heater sub-assembly 23 and the Peltier element sub-assembly 25, system hysteresis is taken into account and, furthermore, damage to the Peltier element 51 can be prevented.

[0052] Alternatively to monitoring the temperature of the sample 2 using the temperature sensors 35, 55, the temperature of the sample 2 (based on which the translation system 27 is operated) can be estimated using one or more of the following: the temperature applied to the electrical resistance heating element 31 supplied current / voltage; the current / voltage supplied to the Peltier element 51; and the flow rate of the heat exchange fluid in the heat exchange subsystem.

[0053] A specific procedure for operating the Fig. The temperature control system 10 shown in Figure 5 is used to increase the temperature of sample 2 from below the first threshold temperature to above the first threshold temperature. Optional steps are shown in dashed lines in the figure. Initially, the sample is below the first threshold temperature (step 100). At temperatures below the first threshold temperature, the temperature control system 10 is in the engaged position and the Peltier element subassembly 25 is in contact with the heater subassembly 23 (step 101). The Peltier element 51 serves to heat the sample 2 (step 102) as it provides finer control. Optionally, the electrical resistance heating element 31 can be used in tandem (step 103) with the Peltier element 51 to provide faster heating of the sample 2. The temperature of the heater subassembly (measured by the sensor 35) increases to the first threshold temperature (step 105).

[0054] When the heater subunit temperature reaches the first threshold temperature, the translation system 27 is operated to move the temperature control system 10 and the Peltier element subunit 25, specifically, to the separated position (i.e., with the Peltier element subunit 25 out of contact with the heater subunit 23 - step 107). Then, the sample 2 is heated by the electrical resistance heating element 31 alone to heat it above the first threshold temperature (step 109).

[0055] After the temperature control system 10 is moved to the disconnected position, the Peltier element subunit 25 is maintained at a standby temperature, i.e., while out of contact with the heater subunit 23 (step 111). The standby temperature is less than or equal to the first threshold temperature and is a temperature at which no deterioration of the Peltier element 51 occurs, thereby protecting the Peltier element 51. However, the standby temperature is close to the first threshold temperature (within 10°C to 30°C of the first threshold temperature), and therefore the Peltier element subunit 25 has a suitable temperature to begin controlling the sample 2 when the desired temperature of the sample 2 returns below the standby temperature. The standby temperature may be equal to the second threshold temperature.The temperature of the Peltier element subassembly 25 is controlled using the electrical current supplied to the Peltier element 51 in addition to the Peltier element heat exchanger 57. The Peltier element temperature sensor 55 serves to provide feedback on the temperature of the Peltier element subassembly.

[0056] Another method for operating the Fig.The temperature control system 10 shown in Figure 6 is used to reduce the temperature of sample 2 from above the second threshold temperature to below the second threshold temperature. Initially, the temperature of the heating sub-unit 23 is above the second threshold temperature (step 120). At temperatures above the second threshold temperature, the temperature control system 10 is in the disconnected position and the Peltier element sub-unit 25 is out of contact with the heating sub-unit 23 (step 121). The heating heat exchanger 37 is used at this point to cool the sample 2 (step 123). The temperature of the heating sub-unit 23 is reduced to the second threshold temperature (step 125).

[0057] When the temperature of the heating sub-assembly 23 reaches the second threshold temperature, the translation system 27 is operated to move the temperature control system 10, and in particular the Peltier element sub-assembly 25, into the engaged position (i.e., with the Peltier element sub-assembly 25 in contact with the heating sub-assembly 23 - step 127). Sample 2 is then further cooled by the Peltier element 51 below the second threshold temperature (step 129), as this provides finer control at these temperatures. Alternatively, the translation system 27 may not be operated to move the temperature control system 10 into the engaged position until sample 2 reaches the standby temperature.

Claims

[1] Temperature control system (10) for a rheometer or a viscometer, the temperature control system (10) comprising: a heating subunit (23) comprising at least one electrical resistance heating element (31); a Peltier element subunit (25) comprising at least one Peltier element (51); and a displacement system (27) arranged to bring the Peltier element sub-unit (25) into and out of contact with the heating sub-unit (23). [2] Temperature control system (10) according to claim 1, wherein the heating sub-unit (23) and / or the Peltier element sub-unit (25) further comprise at least one temperature sensor (35, 55) for measuring the temperature of at least a portion of the heating sub-unit (23) and / or the Peltier element sub-unit (25). [3] Temperature control system (10) according to claim 1 or 2, wherein the displacement system (27) is arranged to bring the Peltier element sub-unit (25) into and out of contact with the heating sub-unit (23) based on at least one or more of: a temperature of the Peltier element subunit (25); a temperature of the heating sub-unit (23); and a temperature of a sample (2) . [4] Temperature control system (10) according to one of the preceding claims, wherein the heating sub-unit (23) and / or the Peltier element sub-unit (25) further comprise at least one heat exchanger (37, 57) for removing heat from the sub-unit (23, 25). [5] The temperature control system (10) of claim 4, wherein the at least one heat exchanger (37, 57) comprises one or more of the following: a liquid heat sink, a gas-cooled heat sink, cooling fins, and a fan. [6] Temperature control system (10) according to claim 4 or 5, wherein the heat exchanger (37) of the heating sub-unit (23) is positioned between the electrical resistance heating element (31) and the Peltier element (51). [7] The temperature control system (10) of any preceding claim, wherein the heater subassembly (23) includes a first thermally conductive material (33) in thermal contact with the electrical resistance heating element (31) and the Peltier element subassembly (25) includes a second thermally conductive material (53) in thermal contact with the Peltier element (51), and bringing the Peltier element subassembly (25) into and out of contact with the heater subassembly (23) includes bringing the first thermally conductive material (33) into and out of contact with the second thermally conductive material (53). [8] Temperature control system (10) according to one of the preceding claims, wherein a first surface (28) of the heating sub-unit (23) is arranged to be close to the sample (2), and a distance between a second surface of the heating sub-unit (23) and the Peltier element sub-unit (25) is adjustable under the action of the displacement system (27). [9] Temperature control system (10) according to any one of the preceding claims, wherein the displacement system (27) is configured to separate the sub-units such that a gap of at least 1 mm is present between the heating sub-unit (23) and the Peltier element sub-unit (25) in response to the temperature of the Peltier element sub-unit (25) being greater than a threshold temperature. [10] Temperature control system (10) according to one of the preceding claims, wherein the displacement system (27) brings the Peltier element sub-unit (25) into and out of contact with the heating sub-unit (23) via a displacement actuator (75) or by displacement caused by thermal expansion or contraction. [11] Temperature control system (10) according to one of the preceding claims, further comprising a controller (30), wherein the controller (30) is arranged to control the sample temperature by adjusting one or more of the electrical resistance heating element (31), the Peltier element (51), the displacement system (27) and the heat exchangers (37, 57). [12] Temperature control system (10) according to claim 11, dependent on claim 2, wherein the controller (30) is arranged to receive data from the at least one temperature sensor (35, 55) as a control input. [13] System for measuring rheological properties of a sample (2), comprising: a deformation actuator (201); a measuring device (202) for measuring a force and / or a torque exerted on the sample (2) and a deformation of the sample (2); a rotor (13); a stator (15); and a temperature control system (10) according to any one of the preceding claims, wherein: the deformation actuator (201) is configured to move the rotor (13) relative to the stator (15) in order to deform the sample (2) positioned between the rotor (13) and the stator (15). [14] A method for controlling a temperature of a sample (2) analyzed by a rheometer or viscometer, comprising: Loading the sample (2) into the rheometer or viscometer; Adjust the temperature of the sample (2) with one or both of: a heating subunit (23) comprising at least one electrical resistance heating element (31); and a Peltier element subunit (25) including at least one Peltier element (51); and in response to a temperature of the heating sub-unit (23), operating a translation system (27) to move the Peltier element sub-unit (25) into and out of contact with the heating sub-unit (23). [15] The method of claim 14, further comprising a first mode of operation in which: the temperature of the sample (2) is increased from below a first threshold temperature to above the first threshold temperature; and the displacement system (27) is operated to bring the Peltier element sub-unit (25) out of contact with the heating sub-unit (23). [16] The method of claim 15, wherein in the first mode of operation, the method further comprises maintaining the Peltier element subassembly (25) at a standby temperature when not in contact with the heating subassembly (23), the standby temperature being less than or equal to the first threshold temperature. [17] A method according to any one of claims 14 to 16, wherein the method comprises a second mode of operation in which: the temperature of the sample (2) is reduced from above a second threshold temperature to below the second threshold temperature; and the displacement system (27) is operated to bring the Peltier element sub-unit (25) into contact with the heating sub-unit (23). [18] The method of claim 17 when dependent on claim 16, wherein the second threshold temperature is equal to the standby temperature. [19] A method according to any one of claims 15 to 18, wherein the method comprises a third mode of operation in which the temperature of the sample (2) is increased from a first temperature to a second temperature below the first threshold temperature, wherein the temperature of the sample (2) is increased using both the electrical resistance heating element (31) and the Peltier element (51).

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