Refrigerating apparatus and method of its operation

FIELD: mechanics.

SUBSTANCE: invention relates to a refrigerating apparatus with a thermal insulation cabinet (1) enclosing a refrigeration chamber (2) with an evaporator (7) being set in the cabinet and with an ice layer (13) being formed on the evaporator surface. Two temperature sensors (12, 14) are fitted close to the evaporator (7) so that only one temperature sensor (12) is buried in the ice layer (13). The control circuit (10) is connected to the two temperature sensors (12, 14) so that to define difference of the temperatures measured by the temperature sensors and so that depending on the defined difference to turn or not to turn on the evaporator (7) defrostation by applying an output signal; the above definition is carried out in case the temperature alteration speed measured by at least one of the two sensors (12, 14) falls below the specified limit.

EFFECT: increasing refrigerating apparatus reliability.

7 cl, 4 dwg

 

The technical field

The present invention relates to a refrigerating apparatus with a heat-insulating housing surrounding the internal chamber, and located in the housing of the evaporator. During operation of the refrigeration apparatus to the evaporator condenses moisture from the inner chamber, and this moisture over time forms a layer of ice, thermally insulating the evaporator from a cooled camera. This isolation reduces the efficiency of the refrigeration apparatus, so that to ensure economical operation of the refrigerator, the ice layer is necessary from time to time to thaw.

The level of technology

It is difficult to determine the optimal time for thawing. Each process of thawing is associated with the introduction of heat into the refrigeration apparatus that you need to take when resuming normal operation of the refrigerator, which also affects the energy balance of the apparatus. So too frequent defrosting is as inefficient as too rare.

It is therefore desirable to have a cooling apparatus, which is based on the estimation of the thickness of the ice cover on the evaporator allows you to receive automatic solution, is desirable if the defrosting operation or not.

To do this, it would be advisable to have an opportunity to directly measure the thickness of the ice layer on the evaporator and this core is the so called automatically decide whether defrosting or not. However, sensors that can directly measure the thickness of the ice layer on the evaporator, the road, and their lifespan is much shorter than the other components of the conventional cooling apparatus, so that their use in refrigerating apparatus would significantly increase its need for repairs.

For this reason, most modern refrigeration apparatus of the type No Frost (i.e. refrigerators without numerazione ice) is used, the defrost control time, when the control system of the refrigeration apparatus starts the defrosting process at fixed intervals. Although this method is reliable and cheap, but it has the disadvantage consists in the impossibility of adapting to different climatic conditions under which operated refrigeration apparatus. This means that "proportionate" in the middle between the two thawing can easily be too long, if the apparatus is operated in a warm environment, when every time you open the door in the refrigerating chamber is made large amounts of moisture, and consequently the layer of ice on the evaporator increases rapidly. At the same time, in the case of operation of the refrigeration apparatus in a cold environment with a small quantity of moisture over a longer period than fitted the config, could improve the efficiency of the refrigeration apparatus. In addition, this method does not take into account the fact that the quantity of moisture depends not only on the duration of operation of the refrigeration apparatus, but also on the number of opening doors, and from the character contained in the apparatus of products.

Disclosure of inventions

The objective of the invention is to create a cooling device that allows you to reliably estimate the amount accrued on the evaporator ice simple and reliable means and method for operating a refrigeration device.

This problem is solved refrigerating apparatus with signs of paragraph 1 of the formula and method of operating with signs of paragraph 6 of the claims.

The invention uses the change in temperature distribution in the vicinity of the evaporator due to the presence of ice cover. If the evaporator no ice, heat flow in the vicinity of the evaporator substantially meets with obstacles, the temperature gradient is relatively flat and the temperature difference measured by the two sensors. If the heat flow is prevented by the layer of ice, the ice layer occurs relatively steep temperature gradient that causes a large difference between the temperatures measured by the two sensors than when both sensors are free of ice.

In particular, one of the sensors the temperature can be set directly on the surface of the evaporator, and the other some distance away from the surface. This ensures that at least the first very quickly reacts to changes in temperature of the evaporator, when after a pause in the evaporator again starts flowing refrigerant.

It is also possible placement of both temperature sensors at different, but not vanishingly small distances from the surface of the evaporator. This little device responds to the thickness of the ice cover, if it is insufficient to cover one of the temperature sensors; but when the boundary layer of ice will lie between the sensors, the temperature difference measured between them, will be very sensitive to further increase the thickness of the ice.

Measurement applicable to refrigerating apparatus in which the evaporator is located directly in the refrigerator or in thermal contact with it.

In such refrigerating devices automatic defrosting of the evaporator with built-in heater is impractical, as allocated by the heater, the heat is distributed in the refrigerating chamber of the apparatus and simultaneously heats the cooled it products. However, the output signal of the control circuit in such a refrigeration apparatus may be used to activate the indicator that notifies the user about the necessity of thawing.

A preferred object of the invention I is comprised of a refrigeration unit type No Frost, i.e. such a refrigeration apparatus in which the evaporator is located in the channel, soobshayem with a freezer, and can be in the channel is heated for defrosting to avoid simultaneous forced heating refrigerating chamber.

In this refrigeration apparatus, one of the temperature sensors located on the surface of the evaporator, and the other at the output of the channel leading into the cooling chamber.

A short list of drawings.

Other characteristics and advantages of the invention ensue from the following description of examples of implementation with reference to the accompanying figures. They presented:

Figure 1 - schematic section of the refrigeration apparatus in accordance with a first variant implementation of the invention;

Figure 2 - dependence of the measured sensor temperature difference of the thickness of ice on the evaporator in a variant implementation of the invention of figure 1;

Figure 3 - schematic representation parts for refrigeration apparatus in the second embodiment of the invention;

Figure 4 - the relationship between the thickness of the ice layer and the temperature difference at the second variant implementation of the invention.

The implementation of the invention

Figure 1 in highly schematized form of refrigerating apparatus of the type No Frost according to the first variant implementation of the invention. Refrigerating apparatus has vypolnennymi way of the insulating housing 1, where the refrigerating chamber 2 for accommodating refrigerated products and separated from the refrigerating chamber 2 partition 3 evaporation chamber 5, soamsawali with refrigerating chamber 2 through the holes 4 in the partition 3. In the evaporation chamber 5 is lamellar evaporator 7 is supplied to the refrigerant of the refrigerating machine 6, and are in close contact with the evaporator, the defrost heater 8.

Evaporation chamber 5 together with the holes 4 is also referred to as an air channel.

The control circuit 10 controls the operation of the refrigerating machine 6 and installed at the top of the hole 4 of the fan 11 in dependence on the measurement signal from the temperature sensor (not illustrated)installed in the refrigerating chamber 2. Refrigerating machine 6 and the fan 11 can be switched on and off simultaneously. However, it is preferable that the fan 11 has been turned on and off with some delay relative to the refrigerating machine 6 to first give the evaporator 7 a chance to cool off, before starting air circulation, and to have some time to use the residual cold of the evaporator 7 after turning off the refrigerating machine 6.

The first temperature sensor 12 is attached directly to the surface of the evaporator 7, which, when the fan 11 is flown air is om, recirculating air channel, and consequently condenses moisture from this air flow and over time it forms a layer of ice, depicted as rarely shaded surface.

The second temperature sensor 14 is installed in the upper hole 4, from which the air is cooled in the evaporation chamber 5 is returned back to the refrigerating chamber 2.

In order to maintain the temperature in the refrigerating chamber 2 within the specified limits, the evaporator 7, as is usually done, works, i.e. receives liquid refrigerant from the refrigeration machine in intermittent mode. The control circuit 10 measures the difference between the temperature values measured by the sensors 12 and 14, or with a given time delay after the input of the evaporator is in operation, or when the rate of change of the temperature measured by one of the temperature sensors 12, 14, falls below the limit value, and therefore, it can be assumed that the temperature distribution in the air channel is not too different from the stationary distribution. The difference between the temperature values measured at this point the temperature sensors 12, 14, less likely, when the thickness of the ice cover is equal to zero, and this difference increases with the thickness of the ice layer. This is clearly shown in the graph in figure 2, where the difference of the temperature is Δ T is depicted as a function of layer thickness d. When this temperature difference ΔT exceed the limit ΔTmax, it is assumed that the thickness of the ice cover 13 has exceeded a critical value dmax, and requires defrosting the evaporator 7. In this case, the control circuit 10 waits until the refrigerating chamber 2 is cooled so that I could disconnect the refrigerating machine 6 and the fan 11, and after this includes a switch 9, which is fed power to the defrost heater 8.

The period of time during which the switch 9 remains closed, fixed, and should be selected based power defrost heater 8 so that given during this period of time the amount of heat was enough to thaw the ice layer 13.

Figure 3 shows schematically in an enlarged scale a section of a refrigeration apparatus according to the second variant implementation of the invention. It differs from the version presented in figure 1, only the placement of the temperature sensors 12', 14', so there is no need again to depict and describe the refrigeration apparatus completely. Two temperature sensor 12', 14' established here on the holder 15 from a material with low heat conductivity, which is attached, for example glued, to the surface of the evaporator 7, which may be formed ice cover 13.

Figure 4 until the Ana under the same conditions, as in the embodiment shown in figure 1, the measured temperature difference ΔT between the sensors as a function of thickness d of a layer of ice. While the thickness of the layer of ice is less than the distance d1 of the temperature sensor 12' from the surface of the evaporator 7, both the temperature sensor are streamed air flow into the evaporation chamber 5, and their temperature is mainly determined by the temperature of this stream. As the distance of the second temperature sensor 14' from the evaporator 7 is greater than the distance of the first sensor 12', the second sensor is still slightly warmer than the first. But when the ice cover 13 will start to grow, capturing the first sensor 12', the temperature equilibrium between the sensors will be broken, and the temperature sensor 12' is greater than the first determined temperature of the evaporator 7, which will manifest itself in the form of fracture of the curve in figure 4, when the thickness d1. The temperature difference will now quickly increase as the layer thickness d. The temperature difference corresponding to the critical thickness of the cover dmax, can have a different value ΔTmax'than in the variant depicted in figure 1. As in the vicinity of dmax can be implemented with a large slope of the curve figure 4, it is possible the accurate and reproducible determination of the critical layer thickness dmax.

1. Refrigeration apparatus with an insulating housing (1)surrounding the refrigerating chamber (2)located in CDF is truncated (1) evaporator (7), the surface of which is in the process forms a layer of ice (13), characterized in that the two temperature sensors (12, 14) are located in the vicinity of the evaporator (7) so that, at a certain thickness of the ice layer (13), only one temperature sensor (12) is immersed in the ice layer (13), and that contains a control circuit (10)connected to two temperature sensors (12, 14) and in the case when the rate of change of the temperature measured at least one of the two sensors (12, 14), falls below the set limit value, to determine the difference (ΔT) between the temperature measured by temperature sensors (12, 14), and based on the difference (ΔT) to include or not to include defrosting the evaporator (7) by submission of the output signal.

2. The refrigeration apparatus according to claim 1, wherein one of the temperature sensors (12) is mounted directly on the surface of the evaporator (7)and the other (14) is at some distance from the surface.

3. The refrigeration apparatus according to claim 1 or 2, characterized in that the evaporator (7) is located in the channel (4, 5), soobshayem with refrigerating chamber (2).

4. The refrigeration apparatus according to claim 3, characterized in that the second temperature sensor (14) is located in the hole (4) channel (4, 5)extending in the refrigerating chamber.

5. The refrigeration apparatus according to one the mu one of claims 1 and 2, 4, characterized in that it contains a heater (8), managed by the specified output signal, and the heater (8) is used to heat the evaporator.

6. A method of operating a refrigerating apparatus, as claimed in any of the preceding paragraphs, comprising the following operations:

a) determine the difference (ΔT) between the temperature measured by temperature sensors (12, 14), and

b) decide on the need defrosting, if the difference (ΔT) exceeds the limit value (ΔTmax),

moreover, steps a) and b) are performed when the rate of temperature change of at least one of the two sensors (12, 14) falls below a defined limit value.

7. The method according to claim 6, characterized in that the heating of the evaporator (7) include, when the decision about the necessity of thawing.



 

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