Freezer and method of its operation

Abstract

A freezer for storing frozen confectionery products, the freezer comprising a substantially sealed openable chamber for storing the frozen confectionery products and having a lower region and an upper region, the lower region comprising air circulation means for directing air from the lower region to the upper region and refrigeration means for chilling the chamber.

Claims

1. A freezer for storing frozen confectionery products, the freezer comprising a substantially sealed openable chamber for storing the frozen confectionery products and having a lower region and an upper region, the lower region comprising air circulation means for directing air from the lower region to the upper region and refrigeration means for chilling the chamber, and wherein the chamber is defined by a base, walls, and an upper surface, the upper surface comprising a viewing window, and wherein the freezer operates the air circulation means such that the air circulation means provide a gentle agitation of air in a generally upwards direction from the lower region of the chamber to the upper region of the chamber; wherein the chamber comprises removable baskets for containing the frozen confectionery products and wherein the air circulation means comprise fans built into the removable baskets.

2. The freezer according to claim 1, wherein the freezer includes frozen confectionery products and the freezer operates the air circulation means such that a temperature gradient between air in the lower region and warmer air in the upper region is maintained, and wherein the temperature gradient in the freezer is such that the difference in average temperature between those products at the top of the chamber and those at the bottom of the chamber is from 1.0 to 4.0 C.

3. The freezer according to claim 2, wherein the difference in average temperature between the upper end of the chamber and the lower end of the chamber is from 1.5 to 3.5 C.

4. The freezer according to claim 2, wherein the temperature at the upper end of the chamber is from 20 to 18 C.

5. The freezer according to claim 2, wherein the temperature at the lower end of the chamber is from 24 to 22 C.

6. A method of operating a freezer including a substantially sealed openable chamber defined by a base, walls, and an upper surface, the upper surface comprising a viewing window, the substantially sealed openable chamber including a removable basket, a lower region configured to store frozen confectionery products and including air circulation means, and an upper region configured to store frozen confectionery products, the method comprising: operating the air circulation means such that a temperature gradient between air in the lower region and warmer air in the upper region is maintained; wherein the temperature gradient in the freezer is such that the difference in average temperature between the frozen confectionery products at the top of the chamber and the frozen confectionery products at the bottom of the chamber is from 1.0 to 4.0 C. wherein the air circulation means comprises a fan built into the removable basket.

7. The method of operating a freezer according to claim 6, wherein the difference in average temperature between the upper end of the chamber and the lower end of the chamber is from 1.5 to 3.5 C.

8. The method of operating a freezer according to claim 6, wherein the temperature at the upper end of the chamber is from 20 to 18 C.

9. The method of operating a freezer according to claim 6, wherein the temperature at the lower end of the chamber is from 24 to 22 C.

Description

(1) The invention will now be illustrated by the following examples and with reference to the following figures, in which:

(2) FIG. 1 is a schematic representation of the underside of a basket for insertion into a chamber of a freezer according to the present invention.

(3) FIG. 2 is a schematic representation of a side view of the basket shown in FIG. 1.

EXAMPLES

(4) A VT300 freezer cabinet comprising product baskets was filled to a typical level with ice cream confectionery products. The freezer was adapted by the installation of small fans (2) at the base of each basket (1), as shown in FIG. 1. The baskets also had a diffuser base extension, to distribute the upwards airflow from the fan more widely across the basket, also as shown in FIG. 1.

(5) The freezer was operated in a stagnant air configuration with the fans turned off and in a configuration where gentle upwards airflow was provided by the fans. The ambient temperature outside the freezer was held at 25 C. and 60% RH. In both cases the freezer was operated to maintain a maximum product temperature of 18 C. The temperature distribution inside the freezer and energy consumption for both modes of operation was measured. The results are shown below in table 1.

(6) TABLE-US-00001 TABLE 1 Original configuration With fans Difference Total energy consumption 2.909 kWh/ 2.784 kWh/ 4.3% 24 h 24 h Energy consumption appliance 2.909 kWh/ 2.708 kWh/ 6.9% 24 h 24 h Energy consumption fan 0 kWh/ 0.077 kWh/ 24 h 24 h Compressor run time 44.4% 40.1% 9.6% Warmest ice cream 18.0 C. 18.0 C. 0% Average temperature of top layer 18.6 C. 18.4 C. 0.2 K ice cream in the basket Average temperature of bottom 23.7 C. 20.8 C. 2.9 K layer ice cream in the basket Temperature difference average 5.1 K 2.4 K 2.7 K top and average bottom layer of ice cream Results at 25 C. and RH = 60% and warmest ice cream at 18 C.

(7) It can be seen that the gentle operation of the fans reduced the temperature gradient from 5.1 C. to 2.4 C. which enabled the temperature at the base of the freezer basket to increase from 23.7 C. to 20.8 C. without substantially changing the temperature at the top of the freezer from 18.6 C. to 18.4 C. The warmer temperature at the bottom of the freezer meant that the refrigeration load was reduced and less energy was consumed. Surprisingly the energy saved in this manner exceeded that spent on the fans, thus reducing the overall energy consumed as compared to the stagnant mode of operation.