ICE-LINED VACCINE REFRIGERATOR

Abstract

An ice-lined vaccine refrigerator includes a vaccine storage compartment, an electrically powered cooling circuit, the electrically powered cooling circuit being configured to generate an ice-lining and to cool the vaccine storage compartment; an AC power inlet adapted for connection to an external supply of AC power; and a refrigerant compressor forming part of the electrically powered cooling circuit and adapted to be powered by the external supply of AC power through the AC power inlet. Reliability is improved by using a DC powered compressor and an AC/DC convertor to convert AC power received at the AC power inlet to DC power to power the compressor.

Claims

1. An ice-lined vaccine refrigerator comprising: a vaccine storage compartment; an electrically powered cooling circuit, the electrically powered cooling circuit being configured to generate an ice-lining and to cool the vaccine storage compartment; an AC power inlet adapted for connection to an external supply of AC power; and a compressor forming part of the electrically powered cooling circuit and adapted to be powered by the external supply of AC power through the AC power inlet; in which the compressor is a DC powered compressor; and in which the ice-lined refrigerator comprises an AC/DC convertor configured to convert AC power received at the AC power inlet to DC power which powers the compressor.

2.-15. (canceled)

16. The ice-lined vaccine refrigerator of claim 1, in which the AC/DC convertor is housed within a body of the ice-lined vaccine refrigerator.

17. The ice-lined vaccine refrigerator of claim 1, in which the AC/DC convertor comprises a transformer configured to reduce the voltage of the AC power received at the AC power inlet and a rectifier to convert the AC power to DC power.

18. The ice-lined vaccine refrigerator of claim 17, in which an overvoltage protection relay is arranged between the i) AC power inlet and ii) the transformer and rectifier, the overvoltage protection relay being configured to disconnect the transformer and rectifier from the supply voltage in the case of the supply voltage exceed an upper cut-out voltage.

19. The ice-lined vaccine refrigerator of claim 1, in which the compressor and the AC/DC converter are configured such that the compressor is operable on the basis of an external supply of AC power is anywhere within the range of 90 V to 280 V and 50-60 Hz.

20. The ice-lined vaccine refrigerator of claim 1, in which the external supply of AC power is an electrical grid electricity supply.

21. The ice-lined vaccine refrigerator of claim 20, in which the electrical grid electricity supply is provided to the AC power inlet without passing through a voltage stabilizer.

22. The ice-lined vaccine refrigerator of claim 1, in which the DC powered compressor is operable on the basis of a DC compressor inlet voltage which is anywhere within the range 20 V to 28 V.

23. The ice-lined vaccine refrigerator of claim 1, in which the ice-lined vaccine refrigerator further comprises a DC power inlet configured to receive DC power from an external DC power source to power the DC compressor.

24. The ice-lined vaccine refrigerator of claim 23, in which the DC power inlet is configured to receive a DC voltage anywhere in the range of 10 V to 28 V to power the compressor.

25. The ice-lined vaccine refrigerator of claim 23, in which the ice-lined refrigerator comprises an automated electronic circuitry configured to select the power source for the compressor between i) the AC power inlet, ii) the DC power inlet, and iii) a combination of the AC power inlet and the DC power inlet.

26. The ice-lined vaccine refrigerator of claim 1, in which the ice-lined vaccine refrigerator is configured to i) ensure that, during operation, the temperature in the vaccine storage compartment is ≥2° C. and ≤8° C. and ii) to ensure a hold-over time of at least 20 hours.

27. The ice-lined vaccine refrigerator of claim 20, in which the AC electrical grid electricity supply is the only power source used to power the DC powered compressor of the electrically powered cooling circuit.

28. The ice-lined vaccine refrigerator of claim 21, in which the AC electrical grid electricity supply is the only power source used to power the DC powered compressor of the electrically powered cooling circuit.

29. The ice-lined vaccine refrigerator of claim 23, in which the external DC power source comprises one or more solar panels.

30. An ice-lined vaccine refrigerator comprising: a vaccine storage compartment; an electrically powered cooling circuit, the electrically powered cooling circuit which generates an ice-lining and cools the vaccine storage compartment; an AC power inlet connected to an external supply of AC power; and a compressor forming part of the electrically powered cooling circuit, the compressor being powered by the external supply of AC power through the AC power inlet; in which: the compressor is a DC powered compressor; the ice-lined refrigerator comprises an AC/DC convertor which converts AC power received at the AC power inlet to DC power which powers the compressor; the AC/DC convertor comprises a transformer which reduce the voltage of the AC power received at the AC power inlet and a rectifier which converts the AC power to DC power; the ice-lined vaccine refrigerator further comprises an overvoltage protection relay arranged between i) the AC power inlet and ii) the transformer and rectifier, the overvoltage protection relay being configured to disconnect the transformer and rectifier from the supply voltage in the case of the supply voltage exceeding an upper cut-out voltage; the compressor and the AC/DC converter are configured such that the compressor is operable when the external supply of AC power is anywhere within the range of 90 V to 280 V and 50-60 Hz; the external supply of AC power is an electrical grid electricity supply provide to the AC power inlet without passing through a voltage stabilizer; and the electrical grid electricity supply is the only power source used to power the DC powered compressor of the electrically powered cooling circuit.

31. The ice-lined vaccine refrigerator of claim 30, in which the electrical grid electricity supply is an unrelatable electrical grid AC electricity supply.

Description

[0053] An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0054] FIG. 1 is a schematic perspective view of an ice-lined vaccine refrigerator;

[0055] FIG. 2 is a schematic top view (without the lid) of the ice-lined vaccine refrigerator;

[0056] FIG. 3 is a schematic view of electrical components and of the electrically powered cooling circuit of the ice-lined vaccine refrigerator; and

[0057] FIG. 4 is a schematic view of an alternative arrangement of electrical components.

[0058] The ice-lined vaccine refrigerator 10 comprises an insulated, moulded body 11 having an insulated pivoted lid 12. A cooling space 13 within the body 11 is accessible when the lid 12 is open and sealable by closing of the lid 12. Electrical components and control circuitry of the refrigerator 10 are arranged within a component housing 14 which is incorporated into the mounded body 11.

[0059] In particular, the ice-lined vaccine refrigerator 10 comprises: [0060] a vaccine storage compartment 15 within the cooling space 13; [0061] an electrically powered cooling circuit 16, [0062] an AC power inlet 17 adapted for connection to an external supply of AC power provided from an electricity grid 18 by a power cable 19 fitted with an electrical plug 20 adapted for the intended country of use; and [0063] a compressor 21 forming part of an electrically powered cooling circuit 16 of the vaccine refrigerator 10.
The compressor 21 is powered indirectly from the AC electricity grid 18 through the AC power inlet 17. The AC power inlet 17 is connected to the input of an overvoltage protection relay 23 with the outlet of the overvoltage protection relay 23 being connected to the input of a combined transformer and AC/DC convertor 24. The overvoltage protection relay 23 has an operational voltage of 150-450V 50/60 Hz AC; whenever the supply voltage received at the AC power inlet exceeds 290V, the relay cuts off the power supply to the transformer for at least 180 s. If after 180 s the supply voltage has dropped below 290V, it will switch back the power supply, and otherwise keep on waiting. The transformer and AC/DC convertor 24 is configured to operate with an input from the AC power inlet 17 in the range 100-240 V AC 50/60 Hz, 3.0 A and to provide an output to the compressor 21 of +24 V DC, 10 A.

[0064] The electrically powered cooling circuit 16 comprises: four flat plate evaporators 25a, 25b, 25c, 25d, each arranged at a peripheral side wall of the cooling space 13, the evaporators being fed with refrigerant which is circulated by the compressor 21 through a condenser 31, subsequently through an expansion valve 32 and subsequently through the evaporators before returning to the compressor 21. A separator plate 26 is arranged within the cooling space 13, the internal periphery of the separator plate 26 defining the side walls of the vaccine storage compartment 15. The separator plate 26 comprises a metal sheet, notably an aluminium sheet, having a thickness of 1-2 mm, provided with a layer of insulation 27, notably a sheet of polystyrene, covering each of its surfaces which faces an evaporator plate 25a, 25b, 25c, 25d. An ice pack 28a, 28b, 28c, 28d is arranged in each of the spaces between the evaporator plates 25a,25, 25c, 25d and the separator plate 26. In operation, the electrically powered cooling circuit 16 freezes the icepacks 28a, 28b, 28c, 28d which generates an ice lining and cools the vaccine storage compartment 15.

[0065] The arrangement of the insulated separator plate 26 between the ice packs 28a, 28b, 28c, 28d and the vaccine storage compartment 15 reduces the risk of undesirably cooling the vaccine storage compartment 15 to a temperature of below +2° C. Furthermore, a separate heating system (not shown) and associated control system is provided to raise the temperature of the vaccine storage compartment 15 if needed; this provides a safeguard to ensure that the temperature of the vaccine storage compartment 15 does fall below +2° C.

[0066] In the arrangement illustrated in FIG. 4, ice-lined refrigerator 10 further comprises a DC power inlet 29 configured to receive DC power from an external DC power source, for example a 24 V DC supply from one or more solar panels, as an auxiliary power supply to power the DC compressor. The DC power inlet in this case may comprise an electrical socket compatible with, preferably only compatible with, a specified DC power supply. An associated protection or cut-out circuit may be provided to avoid component damage in the event of the DC inlet being connected to an inappropriate power supply. In the illustrated arrangement, a power selector relay 30 receives power inlets from each of the DC power inlet 29 and the AC power inlet 17, the input from the AC power inlet 17 preferably being received indirectly after passage through the overvoltage protection relay 23 and transformation to DC power by the combined transformer and AC/DC convertor 24. The compressor 21 in this case can be powered by the power selector relay 30 on the basis of i) only power from the AC power inlet 17; ii) only power from the DC power inlet 29 or iii) power from both the AC power inlet 17 and the DC power inlet 29. The selection of the power source for the compressor in this case may be made using appropriate control circuitry.

LIST OF REFERENCE NUMBERS

[0067] 10 ice-lined vaccine refrigerator [0068] 11 moulded body [0069] 12 lid [0070] 13 cooling space [0071] 14 component housing [0072] 15 vaccine storage compartment [0073] 16 electrically powered cooling circuit [0074] 17 AC power inlet [0075] 18 electricity grid [0076] 19 power cable [0077] 20 electrical plug [0078] 21 compressor [0079] 22 electrically powered cooling circuit [0080] 23 overvoltage protection relay [0081] 24 transformer and AC/DC convertor [0082] 25a evaporator [0083] 25b evaporator [0084] 25c evaporator [0085] 25d evaporator [0086] 26 separator plate [0087] 27 insulation [0088] 28a ice pack [0089] 28b ice pack [0090] 28c ice pack [0091] 28d ice pack [0092] 29 DC power inlet [0093] 30 power selector relay [0094] 31 condenser [0095] 32 expansion valve