Insulation-time determining device for a thermally insulated container

Abstract

An insulation-time determining device for a thermally insulated container with a latent heat accumulator includes energy-calculating equipment for calculating the amount of thermal energy stored in the latent heat accumulator from at least one status parameter of the thermally insulated container or the interior thereof as well as display equipment for displaying the calculated amount of stored thermal energy or a value correlated therewith. The insulation-time determining device also includes insulation-time calculating equipment to calculate a maximum insulation time provided with a safety correction factor of the thermally insulated container from the calculated amount of stored thermal energy or a value correlated therewith and a specified external temperature progression outside the thermally insulated container, during which maximum insulation time a specified temperature range is neither fallen below nor exceeded in the interior of the thermally insulated container.

Claims

1. An insulation-time determining system, comprising: a thermally insulated container with a latent heat accumulator; a sensor to measure at least one status parameter of the thermally insulated container or an interior thereof, energy-calculating equipment configured to calculate an amount of thermal energy stored in the latent heat accumulator from at least one status parameter of the thermally insulated container or an interior thereof, display equipment configured to display the calculated amount of stored thermal energy or a value correlated therewith, an input unit configured to enter an external temperature progression, wherein the external temperature progression is defined in the insulation-time determining device by specifying a known temperature progression via the input unit; and insulation-time calculating equipment, configured to calculate a maximum insulation time provided with a safety correction factor of the thermally insulated container from the calculated amount of stored thermal energy or a value correlated therewith and the specified external temperature progression outside the thermally insulated container, during which maximum insulation time a specified temperature range is neither fallen below nor exceeded in the interior of the thermally insulated container, wherein the amount of thermal energy stored in the latent heat accumulator is calculated by the energy-calculating equipment to ensure the maximum insulation time the specified temperature range is neither fallen below nor exceeded in the interior of the thermally insulated container based on determining a status in an upper section of the thermally insulated container or a status in a lower section of the thermally insulated container.

2. The insulation-time determining device according to claim 1, wherein the at least one status parameter is at least one temperature in the interior of the thermally insulated container.

3. The insulation-time determining device according to claim 2, wherein the latent heat accumulator comprises a phase change material and the insulation-time determining device comprises equipment configured to determine the electric resistance of the phase change material as a status parameter of the thermally insulated container.

4. The insulation-time determining device according to claim 2, further comprising at least one temperature sensor configured to measure at least one temperature in the interior of the thermally insulated container.

5. The insulation-time determining device according to claim 4, wherein the latent heat accumulator comprises a phase change material and the insulation-time determining device comprises equipment configured to determine the electric resistance of the phase change material as a status parameter of the thermally insulated container.

6. The insulation-time determining device according to claim 1, wherein the latent heat accumulator comprises a phase change material and the insulation-time determining device comprises equipment configured to determine the electric resistance of the phase change material as a status parameter of the thermally insulated container.

7. The insulation-time determining device according to claim 1, wherein the latent heat accumulator comprises a phase change material and the insulation-time determining device comprises equipment configured to determine the optical density of the phase change material as a status parameter of the thermally insulated container.

8. The insulation-time determining device according to claim 1, wherein the display equipment is arranged at the thermally insulated container.

9. A method for determining a maximum insulation time provided with a safety correction factor of a thermally insulated container with a latent heat accumulator, comprising: providing a sensor to measure at least one status parameter of the thermally insulated container or an interior thereof, calculating an amount of thermal energy stored in the latent heat accumulator from at least one status parameter of the thermally insulated container or an interior thereof, receiving a specified external temperature progression outside the thermally insulated container, wherein the external temperature progression is defined in an insulation-time determining device by specifying a known temperature progression via an input unit; and calculating a maximum insulation time provided with a safety correction factor of the thermally insulated container from the calculated amount of stored thermal energy and the specified external temperature progression outside the thermally insulated container, during which maximum insulation time a specified temperature range is neither fallen below nor exceeded in the interior of the thermally insulated container, wherein the amount of thermal energy stored in the latent heat accumulator is calculated to ensure the maximum insulation time the specified temperature range is neither fallen below nor exceeded in the interior of the thermally insulated container based on determining a status in an upper section of the thermally insulated container or a status in a lower section of the thermally insulated container.

10. The method according to claim 9, wherein the at least one status parameter is at least one temperature in the interior of the thermally insulated container or the electric resistance or the optical density of a phase change material of the latent heat accumulator.

11. The method according to claim 10, wherein the calculation of the maximum insulation time provided with a safety correction factor of the thermally insulated container from the amount of stored thermal energy and from the specified external temperature progression outside the thermally insulated container is calibrated through prior comparative measurements with the thermally insulated container.

12. The method according to claim 9, wherein the calculation of the maximum insulation time provided with a safety correction factor of the thermally insulated container from the amount of stored thermal energy and from the specified external temperature progression outside the thermally insulated container is calibrated through prior comparative measurements with the thermally insulated container.

13. The method according to claim 9, wherein the calculated amount of stored thermal energy or a value correlated therewith and/or the maximum insulation time provided with a safety correction factor is displayed with display equipment.

14. A method for determining a maximum insulation time provided with a safety correction factor of a thermally insulated container with a latent heat accumulator, comprising: providing a sensor to measure at least one status parameter of the thermally insulated container or an interior thereof, calculating an amount of thermal energy stored in the latent heat accumulator from at least one status parameter of the thermally insulated container or an interior thereof, receiving a specified external temperature progression outside the thermally insulated container; and calculating a maximum insulation time provided with a safety correction factor of the thermally insulated container from the calculated amount of stored thermal energy and the specified external temperature progression outside the thermally insulated container, during which maximum insulation time a specified temperature range is neither fallen below nor exceeded in the interior of the thermally insulated container, wherein for the calculation of the maximum insulation time provided with a safety correction factor of the thermally insulated container, a smallest number n is calculated, starting from which it applies that
E.sub.t.sub.0+.sub.i=1.sup.nE.sub.i(T.sub.i.Math.Y.sub.+(T.sub.i),t.sub.i.Math.(t.sub.i),.Math.()>E.sub.max.Math.(E.sub.max), and with t.sub.max+=.sub.i=1.sup.nt.sub.i a maximum insulation time provided with a safety correction factor of the thermally insulated container t.sub.max+ is calculated, during which a selectable maximum permissible temperature T.sub.max is not exceeded in the interior of the thermally insulated container, wherein: E.sub.t.sub.0 is an amount of stored thermal energy at a starting point-in-time t.sub.0; E.sub.max is a maximum permissible amount of stored thermal energy, which corresponds to a selectable maximum permissible temperature T.sub.max;
t.sub.i=t.sub.it.sub.i-1; t.sub.i is a point-in-time i following starting point-in-time t.sub.0; T.sub.i=T.sub.ex.sub.iT.sub.in.sub.i is a temperature difference between external temperature T.sub.ex.sub.i and internal temperature T.sub.in.sub.i of the thermally insulated container in time interval t.sub.i, wherein one external temperature T.sub.ex.sub.i and one internal temperature T.sub.in.sub.i each are selected for different external temperatures T.sub.ex.sub.i around the thermally insulated container and/or different internal temperatures T.sub.in.sub.i inside the thermally insulated container in time interval t.sub.i; is an energy flow from the interior of the thermally insulated container to the outside or vice versa per Kelvin and second; E.sub.i(T.sub.i.Math..sub.+(T.sub.i), t.sub.i.Math.(t.sub.i), .Math.() is a difference of the amount of stored thermal energy at the points-in-time t.sub.i and t.sub.i-1 depending on temperature difference T.sub.i and the energy flow per Kelvin and second ; .sub.+(T.sub.i)1 for positive T.sub.i and .sub.+(T.sub.i)1 for negative T.sub.i is a safety correction factor for T.sub.i; (t.sub.i)1 is a safety correction factor for t.sub.i; ()1 is a safety correction factor for ; (E.sub.max)1 is a safety correction factor for E.sub.max, wherein the amount of thermal energy stored in the latent heat accumulator is calculated to ensure the maximum insulation time the specified temperature range is neither fallen below nor exceeded in the interior of the thermally insulated container based on determining a status in an upper section of the thermally insulated container or a status in a lower section of the thermally insulated container.

15. The method according to claim 14, wherein E.sub.i(T.sub.i.Math..sub.+(T.sub.i), t.sub.i.Math.(t.sub.i), .Math.())=T.sub.i.Math..sub.+(T.sub.i).Math.t.sub.i.Math.(t.sub.i).Math..Math.().

16. The method according to claim 15, wherein the safety correction factors and the energy flow from the interior of the thermally insulated container to the outside or vice versa per Kelvin and second are determined by prior calibration measurements with the thermally insulated container.

17. The method according to claim 14, wherein the safety correction factors and the energy flow from the interior of the thermally insulated container to the outside or vice versa per Kelvin and second 1 are determined by prior calibration measurements with the thermally insulated container.

18. A method for determining a maximum insulation time provided with a safety correction factor of a thermally insulated container with a latent heat accumulator, comprising: providing a sensor to measure at least one status parameter of the thermally insulated container or an interior thereof, calculating an amount of thermal energy stored in the latent heat accumulator from at least one status parameter of the thermally insulated container or an interior thereof, receiving a specified external temperature progression outside the thermally insulated container; and calculating a maximum insulation time provided with a safety correction factor of the thermally insulated container from the calculated amount of stored thermal energy and the specified external temperature progression outside the thermally insulated container, during which maximum insulation time a specified temperature range is neither fallen below nor exceeded in the interior of the thermally insulated container, wherein for the calculation of the maximum insulation time provided with a safety correction factor of the thermally insulated container, a smallest number m is calculated, starting from which it applies that
E.sub.t.sub.0+.sub.i=1.sup.mE.sub.i(T.sub.i.Math..sub.(T.sub.i),t.sub.i.Math.(t.sub.i),.Math.())<E.sub.min.Math.(E.sub.min), and with t.sub.max=.sub.i=1.sup.mt.sub.i a maximum insulation time provided with a safety correction factor of the thermally insulated container tmax is calculated, during which a selectable minimum permissible temperature T.sub.min is not fallen below in the interior of the thermally insulated container, wherein: E.sub.t.sub.0 is an amount of stored thermal energy at a starting point-in-time to; E.sub.min is a minimum permissible amount of stored thermal energy, which corresponds to a selectable minimum permissible temperature T.sub.min;
t.sub.i=t.sub.it.sub.i-1; t.sub.i is a point-in-time i following starting point-in-time t.sub.0; T.sub.i=T.sub.ex.sub.iT.sub.in.sub.i is a temperature difference between external temperature T.sub.ex.sub.i and internal temperature T.sub.in.sub.i of the thermally insulated container in time interval t.sub.i, wherein one external temperature T.sub.ex.sub.i and one internal temperature T.sub.in.sub.i each are selected for different external temperatures T.sub.ex.sub.i around the thermally insulated container and/or different internal temperatures T.sub.in.sub.i inside the thermally insulated container in time interval t.sub.i; is an energy flow from the interior of the thermally insulated container to the outside or vice versa per Kelvin and second; E.sub.i(T.sub.i.Math..sub.(T.sub.i), t.sub.i.Math.(t.sub.i), .Math.()) is a difference of the amount of stored thermal energy at the points-in-time t.sub.i and t.sub.i-1 depending on temperature difference T.sub.i and the energy flow per Kelvin and second ; .sub.(T.sub.i)1 for negative T.sub.i and .sub.(T.sub.i)1 for positive T.sub.i is a safety correction factor for T.sub.i; (t.sub.i)1 is a safety correction factor for t.sub.i; ()1 is a safety correction factor for ; (E.sub.min)1 is a safety correction factor for E.sub.min, wherein the amount of thermal energy stored in the latent heat accumulator is calculated to ensure the maximum insulation time the specified temperature range is neither fallen below nor exceeded in the interior of the thermally insulated container based on determining a status in an upper section of the thermally insulated container or a status in a lower section of the thermally insulated container.

19. The method according to claim 18, wherein E.sub.i(T.sub.i.Math..sub.(T.sub.i), t.sub.i.Math.(t.sub.i), .Math.())=T.sub.i.Math..sub.(T.sub.i).Math.t.sub.i.Math.(t.sub.i).Math..Math.().

20. The method according to claim 18, wherein the safety correction factors and the energy flow from the interior of the thermally insulated container to the outside or vice versa per Kelvin and second 1 are determined by prior calibration measurements with the thermally insulated container.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the insulation-time determining device according to the invention and the method for determining a maximum insulation time provided with a safety correction factor of a thermally insulated container with a latent heat accumulator according to the invention are described based on an exemplary embodiment illustrated in the drawings. It is shown:

(2) FIG. 1a perspective view of a thermally insulated container with the front wall removed;

(3) FIG. 2the thermally insulated container of FIG. 1 in the closed state with a schematic representation of a dedicated insulation-time calculating equipment;

(4) FIG. 3the thermally insulated container of FIG. 2 with indicated temperature sensors; and

(5) FIG. 4a temperature progression diagram.

DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows a thermally insulated container 1 with walls that are made up of insulation elements, wherein the front wall 11 has been detached from the rest of the thermally insulated container 1 so the latter can be charged. The insulation elements contain phase change material, which serves as a latent heat accumulator. Devices similar to the thermally insulated container 1 are in principle known.

(7) FIG. 2 shows the thermally insulated container 1 of FIG. 1 in the closed state. To this thermally insulated container 1, an exemplary embodiment of the insulation-time determining device 2 according to the invention for determining a maximum insulation time provided with a safety correction factor of the thermally insulated container 1 is attached. The insulation-time determining device 2 comprises a display equipment 21, an energy-calculating equipment 22, an insulation-time calculating equipment 23, an input unit 24 and an external temperature sensor 26, all of which are only schematically depicted here. The energy-calculating equipment 22 and the insulation-time calculating equipment 23 can also be realized together in a calculation unit such as, for example, a computer processor.

(8) FIG. 3 shows the thermally insulated container 1 of FIG. 2 with a large number of schematically represented temperature sensors 25 that are distributed over the interior of the thermally insulated container 1. The temperature sensors 25 deliver temperature values from the interior of the thermally insulated container 1 for the calculation of the amount of thermal energy stored in the latent heat accumulator, and they are for this purpose connected with the energy-calculating equipment 22, either through not represented cables or through wireless communication.

(9) Normally, the temperature sensors 25 in the upper section of the thermally insulated container 1 deliver the highest measured values while the temperature sensors 25 in the lower section of the thermally insulated container 1 deliver the lowest measured values. In order to ensure that the required temperature range is observed inside the entire interior of the thermally insulated container 1, the energy calculation is always based on the most unfavourable temperature value, i.e. on a measurement value from a temperature sensor 25 in the upper section of the thermally insulated container 1 when it is critical not to exceed the maximum permissible temperature and on a measurement value from a temperature sensor 25 in the lower section of the thermally insulated container 1 when it is critical not to fall short of the minimum permissible temperature. Alternatively, it is also possible to use a mean value, but then the safety correction factors .sub.+(T.sub.i) or .sub.(T.sub.i) for T.sub.i must be selected by reflecting correspondingly more unfavourable conditions.

(10) Having calibrated the insulation-time determining device 2 for a specific thermally insulated container 1, this device can be used as a charge level indicator for the latent heat accumulator of the thermally insulated container 1 and, for example, display the following information: one or several interior temperatures, the external temperature, the amount of thermal energy stored in the latent heat accumulator or a current still available energy absorption capacity and/or energy release capacity of the latent heat accumulator that is correlated therewith, the time for several external temperatures until the maximum energy absorption capacity and/or energy release capacity is reached, corresponding to the maximum insulation time for each of the external temperatures in question, and/or other correlated information.

(11) The insulation-time determining device can also be used as a transport planning instrument by entering various temperature scenarios, which correspond to various transport scenarios, via the input unit 24, in an attempt to find an optimal transport scenario that takes into account maximum insulation time and safety margins.

(12) For the use as a transport planning instrument, the temperature sensors 25 and 26 are not required when the system is calibrated. This is why it is possible for this purpose to replace the insulation-time determining device 2 with an insulation-time determining device that is neither attached nor otherwise linked to the thermally insulated container 1, for example a common computer, which may also serve other purposes, that is equipped with a suitable software or that, for example, can access a suitable software via the Internet.

(13) FIG. 4 shows a temperature progression diagram for an exemplary external temperature scenario that could, for example, be represented on the display equipment 21 or a computer screen. The time axis is horizontal, while the axes for the temperature and the energy capacity are vertical.

(14) Reference number 3 marks the external temperature progression, 4 the development of the mean temperature value in the interior of the thermally insulated container 1, 5 the specified minimum permissible temperature T.sub.min (here: 2 C.), 6 the specified maximum permissible temperature T.sub.max (here: 8 C.) and 7 the development of the energy absorption capacity K.sub.E of the latent heat accumulator.

(15) The energy absorption capacity K.sub.E is partly determined by the size of the latent heat accumulator and partly by the amount of thermal energy that has been stored. The larger the amount of thermal energy that has already been stored, i.e. the further the phase transition of the phase change material from solid to liquid has advanced, the smaller the remaining energy absorption capacity K.sub.E. FIG. 4 shows the energy absorption capacity K.sub.E in %, wherein 0% has been defined in such a way that at an energy absorption capacity K.sub.E of 0% the amount of thermal energy stored in the latent heat accumulator corresponds to the maximum permissible temperature T.sub.max, and 100% has been defined in such a way that at an energy absorption capacity K.sub.E of 100% the amount of thermal energy stored in the latent heat accumulator corresponds to a pre-conditioning temperature of the thermally insulated container 1 of 3 C. This energy absorption capacity scale is relative, and it is in principle possible to obtain values that exceed 100% or fall below 0%. It is also possible to select other energy absorption capacity scales.

(16) The internal temperature curve 4 is the result of a large number of measurements, conducted in intervals of 10 seconds each. The energy absorption capacity K.sub.E correlates with the internal temperature T via the amount of stored thermal energy, such that each internal temperature value T corresponds with a value for the energy absorption capacity K.sub.E, resulting in the energy absorption capacity curve 7.

(17) In the represented example, the thermally insulated container 1 starts with an internal temperature T of 4 C. at the starting point-in-time t.sub.0=0 hours and is first subjected to an external temperature of 2 C., which lowers the internal temperature and increases the energy absorption capacity K.sub.E. Following this, the external temperature rises to 16 C., which increases the internal temperature and lowers the energy absorption capacity K.sub.E. On the basis of the external temperature progression 3, the internal temperature curve 4 and the energy absorption capacity curve 7 result.

(18) The vertical line 8 shows that the internal temperature exceeds the maximum permissible temperature T.sub.max of 8 C. after a time period of approx. 273 hours, which means that the maximum insulation time for this scenario is approx. 273 hours. At this point-in-time, the energy absorption capacity K.sub.E also falls to 0%, wherein the representation of FIG. 4 has corrected any lower values to 0%.

(19) Further variations of the insulation-time determining devices and methods described herein may be realized. It is to be noted specifically that the amount of thermal energy stored in the latent heat accumulator also correlates with values that have not been mentioned and that can also be calculated and displayed.