MEASURING DEVICE HAVING AN ELECTROTHERMAL TRANSDUCER FOR ADJUSTING A THERMAL RESISTANCE, AND METHOD OF OPERATING THE SAME

Abstract

A measuring device for thermal analysis of a sample is described, the measuring device comprising: (i) a sample receptacle for receiving the sample, (ii) a heating device for increasing the temperature of the sample receptacle, (iii) a cooling device for reducing the temperature of the sample receptacle, and (iv) a heat transport element having a thermal resistance and being arranged between the heating device and the cooling device such that a heat flow between the heating device and the cooling device via the heat transport element is enabled. Further, the measuring device v) comprises an electrothermal transducer arranged between the heat transport element and the cooling device such that operating the electrothermal transducer adjusts the heat flow through the heat transport element.

Claims

1. A measuring device for thermal analysis of a sample, the measuring device comprising: a sample receptacle for receiving the sample; a heating device for increasing the temperature of the sample receptacle; a cooling device for reducing the temperature of the sample receptacle; a heat transport element having a thermal resistance and being arranged between the heating device and the cooling device such that a heat flow between the heating device and the cooling device is enabled via the heat transport element; and an electrothermal transducer arranged between the heat transport element and the cooling device such that operating the electrothermal transducer adjusts the heat flow through the heat transport element.

2. The measuring device according to claim 1, wherein the electrothermal transducer is operable in a heating mode and/or in a cooling mode.

3. The measuring device according to claim 1, wherein the electrothermal transducer comprises a Peltier element.

4. The measuring device according to claim 1, wherein the electrothermal transducer is arranged between the heat transport element and the cooling device such that a direct contact between the heat transport element and the cooling device is prevented.

5. The measuring device according to claim 1, wherein the sample receptacle comprises two sample containers, and wherein the measuring device is configured to perform a differential measurement with respect to the two sample containers.

6. The measuring device according to claim 1, wherein the measuring device is a differential scanning calorimeter or a differential thermal analysis measuring device.

7. The measuring device according to claim 1, wherein the heating device is adapted to provide a time-dependent increasing temperature profile.

8. The measuring device according to claim 1, wherein the cooling device is adapted to provide a time-dependent decreasing temperature profile.

9. The measuring device according to claim 1, wherein the cooling device comprises at least one of the group consisting of: a heat pipe, a heat sink, a cryostat, a Peltier element, a heat exchanger.

10. The measuring device according to claim 1, wherein the measuring device is configured such that operating the electrothermal transducer comprises: controlling or regulating the thermal resistance of the heat transport path.

11. The measuring device according to claim 1, wherein the measuring device is configured such that operating the electrothermal transducer in a heating mode or turning off the electrothermal transducer increases the thermal resistance of a heat transport path through the heat transport element and the electrothermal transducer, and reduces the heat flow through the heat transport element.

12. The measuring device according to claim 1, wherein the measuring device is configured such that operating the electrothermal transducer in a cooling mode reduces the thermal resistance of the heat transport path through the heat transport element and the electrothermal transducer, and increases the heat flow through the heat transport element.

13. The measuring device according to claim 1, wherein the measuring device is configured such that operating the electrothermal transducer in a cooling mode allows the provision of a lower temperature in the measuring device than without operating the electrothermal transducer in the cooling mode.

14. The measuring device according to claim 13, wherein the lower temperature is minus 40° C. or less.

15. The measuring device according to any claim 1, wherein the heat transport element comprises a metal or a functional ceramic.

16. The measuring device according to claim 15, wherein the metal comprises nickel or a nickel alloy.

17. A method of operating a measuring device for thermal analysis comprising a heating device and a cooling device coupled together by a heat transport element via a heat flow, the method comprising: providing an electrothermal transducer between the heat transport element and the cooling device; operating the electrothermal transducer in a heating mode or turning off the electrothermal transducer in order to reduce the heat flow through the heat transport element; and operating the electrothermal transducer in a cooling mode in order to increase the heat flow through the heat transport element.

18. The method according to claim 17, wherein the method further comprises: providing a sample in a sample receptacle of the measuring device; increasing the thermal resistance of a heat transport path through the heat transport element and the electrothermal transducer if the temperature of the sample receptacle is increased.

19. The method according to claim 17, wherein the method further comprises: providing a sample in a sample receptacle of the measuring device; reducing the thermal resistance of the heat transport path through the heat transport element and the electrothermal transducer if the temperature of the sample receptacle is reduced.

20. A method of using a Peltier element to selectively adjust a heat flow through a heat transport element between a heating device and a cooling device within a measuring device for thermal analysis.

Description

[0051] FIG. 1 shows a measuring device according to an exemplary embodiment of the invention.

[0052] FIG. 2 shows a measuring device according to a further exemplary embodiment of the invention.

[0053] FIG. 3 shows an implementation of the measuring device according to another exemplary embodiment of the invention.

[0054] Before describing the figures in detail, some specific embodiments of the invention are explained below.

[0055] According to an exemplary embodiment, it would be advantageous for a dynamic temperature control if the thermal resistance between the sample chamber (sample receptacle) and the cooling system (cooling device) were high during heating (or when high temperatures are to be maintained), or if the thermal resistance between the sample chamber and the cooling system were low during cooling (or when low temperatures are to be achieved). This problem is solved in that Peltier elements act as variable thermal resistors, which is advantageous for the dynamics and thermal design of the entire measuring device. The Peltier elements do not represent an additional heating or cooling for the furnace (heating device).

[0056] According to another exemplary embodiment, in the heating phase of the measuring device, a Peltier element is brought into heating operation (or alternatively turned off) and the thermal resistance becomes high. In the cooling phase, the Peltier element is brought into cooling mode and a low thermal resistance is established (use of Peltier elements as variable thermal resistance between heating device and cooling device). If the Peltier element is not energized or the Peltier element heats up, the thermal resistance between the heating device and the cooling device is high.

[0057] FIG. 1 schematically shows the structure of a measuring device 100 according to an exemplary embodiment of the invention. The measuring device 100 has a sample receptacle 120 (e.g. two sample containers for a differential measurement) for receiving the sample(s). A heating device for increasing the temperature of the sample receptacle 120 is arranged below the sample receptacle 120. Preferably, the heating device 110 is adapted to provide a time-dependent increasing temperature gradation (i.e. a temperature profile) with respect to the sample. A heat transport element 140 is positioned below the heating device 110, the heat transport element having a thermal resistance (or a specific thermal conductivity). In an embodiment, the heat transport element comprises a nickel alloy. The measuring device 100 further comprises a cooling device 130 for reducing the temperature of the sample receptacle 120 (or for reducing the temperature in the measuring device 100). Preferably, the cooling device 130 is adapted to provide a time-dependent decreasing temperature gradation (i.e. a temperature profile) with respect to the sample. The heating device 110 and the cooling device 130 are spatially separated from each other. Nevertheless, a heat flow between the heating device 110 and the cooling device 130 is enabled by means of the heat transport element 140. However, the heat transport element 140 is not directly connected to the cooling device 130. Instead, an electrothermal transducer 150 (e.g. a Peltier element) is provided directly between the heat transport element 140 and the cooling device 130 in such a way that a direct spatial (physical) contact (or touch) between the cooling device 130 and the heat transport element 140 is prevented (made impossible). The electrothermal transducer 150 is arranged here so that an operation of the electrothermal transducer 150 may selectively and dynamically adjust the heat flow through the heat transport element 140 (or the thermal resistance of the heat transport path through the heat transport element 140 and the electrothermal transducer 150). Operating the electrothermal transducer 150 in a heating mode (or turning off the electrothermal transducer 150) has the effect of reducing the heat flow (or increasing the thermal resistance of the heat transport path 140, 150). Accordingly, this mode will be used if the temperature of the sample receptacle 120 is to be increased. Due to the increased thermal resistance, less produced heat is transported away from the heating device. At the same time, the increased thermal resistance acts as a shield against the cooling device. On the other hand, Operating the electrothermal transducer 150 in a cooling mode has the effect of increasing the heat flow through the heat transport element 140 (or reducing the thermal resistance of the heat transport path 140, 150). Accordingly, this mode will be used if the temperature of the sample receptacle 120 is to be reduced. The reduced thermal resistance allows the heat of the heated sample receptacle to be quickly removed. At the same time, the cooling effect of the cooling device is now no longer shielded.

[0058] FIG. 2 schematically shows the structure of a measuring device 200 according to a further exemplary embodiment of the invention. In contrast to FIG. 1, two cooling devices 130 are provided, each of which is arranged laterally of the heat transport element 140 and the heating device 110, respectively. Accordingly, two electrothermal transducers 150 are used, each of which is inserted between the heat transport element 140 and one of the cooling devices 130. Alternatively, it may be shown that a single cooling device 130 surrounds the heat transport element 140 and/or the heating device 110.

[0059] FIG. 3 shows an implementation of a measuring device 300 as schematically described in FIG. 2 according to an exemplary embodiment of the invention. Along a main axis A, the following are arranged from top to bottom: the sample receptacle 120 (measuring chamber), the heating device 110, a first part 141 of the heat transport element 140, a second part 142 of the heat transport element 140, and an insulating base 180. The first part 141 of the heat transport element 140 is designed in the shape of a tube (barrel) and connects the heating device 110 to the second part 142 of the heat transport element 140, which is designed in the shape of a flange or disc. The shown embodiment of the heat transport element 140 has been found to be advantageous from an energy point of view, but a variety of further (advantageous) embodiments of the heat transport element 140 are possible. Around the first and second parts 141, 142 of the heat transport element 140 a heat coupling element 145 is fixed, which in principle is also a heat transport element 140 (e.g. made of copper). The heat coupling element 145 is optional and, in the example shown, serves an efficient mounting or fixation (of the cooling device 130). Peltier elements 150, which are used as electrothermal transducers to selectively adjust the thermal resistance of the heat transport element 140, are attached along the heat transport element 140 (in particular on the outer face of the heat coupling element 145). The cooling device 130 has two heat sinks, which are arranged laterally of the heat transport element 140 (or perpendicular to the main axis A). As explained above, the Peltier elements 150 are directly fixed (clamped) between the heat transport element 140 and the cooling device 130, thus preventing any physical (spatial) contact between the heat transport element 140 and the cooling devices 130.

[0060] Supplementally, it should be noted that “comprising” does not exclude other elements or steps and “one” or “a” does not exclude a plurality. It should further be noted that features or steps that have been described with reference to any of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims are not to be regarded as a limitation.

REFERENCE SIGNS

[0061] 100, 200, Measuring device [0062] 300 [0063] 110 Heating device [0064] 120 Sample receptacle [0065] 130 Cooling device [0066] 140 Heat transport element [0067] 141 Heat transport element first part [0068] 142 Heat transport element second part [0069] 145 Heat coupling element [0070] 150 Electrothermal transducer, Peltier element [0071] 180 Base