DE19844854A1 - Time independent defrosting of temp. evaporators in refrigerators has defrosting fan and circulating fan - Google Patents

Abstract

The method involves interrupting the flow of air circulating through the goods container (2) of a refrigerator to prevent the harmful heating of the stored frozen goods. In order to maintain the required air flow through the evaporator, a bypass or double floor (10) is used which contains a defrosting fan (9) operational in defrosting mode and which supports the circulating fan (3) in operating mode.

Description

The common freezers of the retail trade are functional and constructional disadvantage that the airflow cooling the frozen goods in turn cooled by a cold evaporator inside the freezer in the Evaporator defrost to remove the inevitable ice build-up the heat exchange surfaces of the air flow used to cool the frozen goods the frozen goods instead of -25 ° C as in cooling mode often to + 15 ° C in defrost mode warms to impermissible.

The legally permissible product temperature of -15 ° C is exceeded and subsequently started microbiological processes that the Reduce the quality of goods significantly. They are now methods and devices become known, which is especially common in the widely used freezers with convection cooling, the frozen goods before the harmful temperature increase as a result To protect defrost.

These methods and / or devices often assume that by reversing the Flow direction shut-off devices automatically interrupt the cooling air flow and then defrosting is carried out in a bypass operation.

It is very unsuitable for retrofitting purposes as well as for new refrigeration units, long Use shut-off devices that correspond to the freezer length and keep functional, since there is always a risk of icing and then appropriate heaters must be provided for this to keep it functional. The control of the function is very complex and can not become part of the operational routine as it is part of the process inside the Freezers are arranged. In addition, again related to retrofitting of freezers that existing fans are not readily available in their Direction of rotation can be changed. According to the invention, a method should now be the Defrost operation so that the shut-off devices are at least easily accessible are and can be monitored routinely. According to the  Possibility of defrosting during business hours perform.

The interference in the technology of the freezer should be kept to a minimum to preserve proven techniques as much as possible.

The solution according to the invention does the following: in a bypass or channel or Raised floor, an additional defrost fan is arranged, which causes the performance of the fan by z. B. speed control, this is easy retrofit, volume and pressure increase can be set so that in connection the entire air flow with the defrost fan operating in the same conveying direction can be guided over the bypass or raised floor and the air intake and Exits of the freezer set air pressure conditions, which the there arranged easily accessible shut-off devices for automatic closing cause.

With sufficiently precise control of the air pressures of the fan and defrost fan with simultaneous compensation of air pressure fluctuations in the system as a result of Fluctuations in the mean air temperature can affect the automatically acting Shut-off devices at the air inlet and outlet are dispensed with, since then there is none There is a pressure drop and no air flow can take place.

Since the frozen goods cannot come into contact with warm defrosting air defrosting can also be carried out during business hours.

The connection of bypass or raised floor arrangement leads in connection with the Defrost fan and, if the regulation is sufficiently precise, also means that there is no need for it Shut-off devices. This novelty according to the invention is therefore also for Freezers, freezer combinations, refrigerated shelves and refrigerated counters. The invention is suitable for new designs and retrofits.

Due to the compact arrangement and air flow, the energy consumption reduced, and since there is no heating of the frozen goods, the goods quality considerably  improved. The invention and its mode of operation is illustrated in the drawings exemplified on a freezer:

Fig. 1 shows a section through a freezer during normal operation

Fig. 2 shows a section through a freezer in defrost mode

Fig. 3.1 and 3.2 show the shut-off devices of the supply air and the exhaust air side of the freezer

In Fig. 1 the normal operation of a freezer ( 1 ) is shown. The recirculated air enters the goods container ( 2 ) cooled through the air inlet opening ( 6 ), cools the frozen goods ( 5 ) there and leaves the goods container ( 2 ) through the air outlet opening ( 7 ). The flow of the recirculated air acts through the fan ( 3 ), flows back through the evaporator ( 4 ) through the air inlet opening ( 6 ) into the goods container ( 2 ).

In Fig. 2 the defrost operation is shown. This is effected as follows: The fan ( 3 ) leads the circulating air via the heater ( 8 ) to the evaporator ( 4 ) in order to remove ice that has settled there. By reducing the air volume and increasing the pressure of the fan ( 3 ), the circulating air is not led to the air inlet opening ( 6 ); instead, the defrost fan ( 9 ) takes over the circulating air through the raised floor ( 10 ). The associated barrier ( 11 ) is open. As a result of the negative pressure that now arises at the air inlet ( 6 ) and air outlet ( 7 ), the shut-off devices ( 12-16 ) that are possible here, if any, close.

The defrost fan ( 9 ) supports the fan ( 3 ) in its task of ensuring the appropriate air pressure in accordance with the intended mode of operation.

Fig. 3.1 and 3.2 show the shut-off devices ( 12-16 ), which automatically close the air inlet ( 6 ) and the air outlet ( 7 ). If sealing is required, film ( 15 ) is supported on the perforated plate ( 12 ) and thus creates the intended seal. Perforated plate ( 12 ) and / or film ( 15 ) are heatable, so that any ice coating that may form can be removed.

Reference list

1

Freezer

2nd

Monitor container

3rd

fan

4th

Evaporator

5

Frozen goods

6

Air intake

7

Air outlet

8th

heater

9

Defrost fan

10th

Raised floor

11

Shut-off device

12th

Perforated sheet

13

Insect repellent

14

Fastening strips

15

foil

16

Weight

Claims (7)

1. A method for making defrosts on the evaporator of a refrigerator, characterized in that the circulating air flow which flows through the container of a refrigerator is interrupted and the harmful heating of the stored frozen goods is prevented. However, in order to maintain the necessary air flow through the evaporator, a bypass or raised floor is arranged which, in the event of defrosting, receives an operating defrosting fan which supports the circulating air fan during this operating state. 2. The method according to claim 1, characterized in that the interruption of the Circulating air flow in the goods container by reducing the output or speed of the fan is effected. 3. The method according to claim 1 and 2, characterized in that the Defrost fan is only in operation during the defrost phase. 4. The method according to claim 1 and the following, characterized in that Air pressure and fan output and defrost fan output set in this way be that an air flow at the air inlet or outlet no longer takes place. 5. The method according to claim 1 and the following, characterized in that at insufficient air pressure control or for safety reasons shut-off devices on Air inlet and outlet can be arranged. 6. The method according to claim 5, characterized in that the shut-off elements in the combination of perforated sheet and foil take effect. 7. The method according to claim i, characterized in that for the Defrosting necessary double bottom receives a shut-off device, which in Normal mode is closed and opened in defrost mode.