EP2781860A2

EP2781860A2 - Refrigerator

Info

Publication number: EP2781860A2
Application number: EP13192107.4A
Authority: EP
Inventors: Jaehoon SHIN; Heayoun Sul; Changho Seo; Yongjoo Park
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2013-03-22
Filing date: 2013-11-08
Publication date: 2014-09-24
Also published as: EP2781860A3; US20140284025A1; CN104061732A; KR20140115837A

Abstract

A refrigerator with a main body including a refrigerating compartment at a temperature higher than a freezing temperature and a freezing compartment at a temperature lower than the freezing temperature, a deep-freezing storage chamber within the main body at a temperature lower than that of the freezing compartment. The refrigerator further includes a compressor, a condenser connected to an outlet-side of the compressor, a first expansion valve connected to an outlet-side of the condenser, a first evaporator connected to an outlet-side of the first expansion valve, and a heater disposed outside the first expansion valve.

Description

BACKGROUND

The present disclosure relates to a refrigerator.
Refrigerators are home appliances for storing foods at a low temperature. For example, a refrigerator includes a refrigerating compartment to store food in a refrigerated state and a freezing compartment to store food in a frozen state.
Recently, demand for a refrigerator including a separate storage chamber for cooling foods within a short time period to an ultralow temperature has increased. To achieve the above-described objects, a separate deep-freezing storage chamber is provided within a freezing compartment. Also, a structure is provided in which cool air within a vaporizing chamber is independently supplied into the deep-freezing storage chamber through a cool air passage connecting the deep-freezing storage chamber to the vaporizing chamber. In the related art, since the cool air within the vaporizing chamber is separately supplied into only the deep-freezing storage chamber, the deep-freezing storage chamber may have a temperature lower than that of the freezing compartment without having an influence on the temperatures of the freezing compartment and the refrigerating compartment.
Generally, refrigerators use an R-600a isobutene refrigerant to lower a temperature of an evaporator to a temperature of about -40°C to about -42°C. However, the deep-freezing storage chamber may require a temperature lower than that of the evaporator, i.e., a temperature of about -50°C. To accomplish this, it may be insufficient to use only the separate deep-freezing storage chamber.
To meet the demand of the deep-freezing cooling as described above, a suction pipe connecting the evaporator to a compressor may exchange heat with an expansion valve. Specifically, in the case where the suction pipe and the expansion valve exchange heat to reduce an evaporation temperature, the refrigerant passing through the expansion valve may further decrease in temperature to increase a heat absorption capacity, thereby increasing a cooling ability. However, since an evaporation pressure itself is not decreased, it may be difficult to decrease the evaporation temperature.
To solve the above-described limitation, an expansion valve having a smaller diameter may be used. However, in this case, although the evaporation pressure is decreased, a saturation achievement rate of the refrigerant may be further reduced when the evaporator absorbs heat to lower the temperature of the deep-freezing storage chamber to a set temperature. That is, the reduction in the saturation achievement rate of the refrigerant represents the reduction in an amount of refrigerant which is saturated to generate a gas by passing through the evaporator. Thus, an amount of liquid refrigerant introduced into a gas/liquid separator is greater than that of gas refrigerant. As a result, the possibility to introduce more liquid refrigerant into the compressor may be further increased. Thus, a condensation pressure and an evaporation pressure in the whole refrigeration cycle may be further increased. Furthermore, the introduction of liquid refrigerant into the compressor may deteriorate performance of the compressor or damage the compressor.

SUMMARY

One or more embodiments provide a refrigerator in which a temperature of a deep-freezing storage chamber is further lowered than that of a deep-freezing storage chamber according to the related art to minimize damage of a compressor, and provide a method for controlling the same.
In one embodiment, a refrigerator including: a main body including a refrigerating compartment maintained at a temperature higher than a freezing temperature and a freezing compartment maintained at a temperature lower than the freezing temperature; a deep-freezing storage chamber disposed within the main body, the deep-freezing storage chamber being maintained at a temperature lower than that of the freezing compartment; a compressor compressing a refrigerant at a high temperature and a high pressure; a condenser connected to an outlet-side of the compressor to condense the high-temperature high-pressure refrigerant; a first expansion valve connected to an outlet-side of the condenser to expand the refrigerant so that the refrigerant has a low-temperature low-pressure two-phase state; a first evaporator connected to an outlet-side of the first expansion valve to change the refrigerant into a low-temperature low-pressure gas refrigerant; and a heater disposed outside the first expansion valve, the heater supplying heat into the first expansion valve to lower an evaporation temperature of the refrigerant to a temperature lower than that of the freezing compartment.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a view illustrating a refrigeration cycle of a refrigerator according to one embodiment.
Fig. 2 is a p-h diagram for comparing the refrigeration cycle according to one embodiment to a general refrigeration cycle according to the related art.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which show by way of illustration specific preferred embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is understood that other embodiments may be utilized. Logical, structural, mechanical, electrical, and chemical changes may be made without departing from the scope of the invention. To avoid detail not necessary to enable those skilled in the art to practice the invention, the description may omit certain information known to those skilled in the art. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present disclosure is defined only by the appended claims.
Hereinafter, a refrigerator and a method for controlling the refrigerator according to one embodiment will be described in detail with reference to the accompanying drawings.
A refrigerator includes: a main body including a refrigerating compartment maintained at a temperature higher than a freezing temperature and a freezing compartment maintained at a temperature lower than the freezing temperature; a deep-freezing storage chamber disposed within the main body, the deep-freezing storage chamber being maintained at a temperature lower than that of the freezing compartment; a compressor compressing a refrigerant at a high temperature and a high pressure; a condenser connected to an outlet-side of the compressor to condense the high-temperature high-pressure refrigerant; a first expansion valve connected to an outlet-side of the condenser to expand the refrigerant so that the refrigerant has a low-temperature low-pressure two-phase state; a first evaporator connected to an outlet-side of the first expansion valve to change the refrigerant into a low-temperature low-pressure gas refrigerant; and a heater disposed outside the first expansion valve, the heater supplying heat into the first expansion valve to lower an evaporation temperature of the refrigerant to a temperature lower than that of the freezing compartment.
The heater may contact an outer circumferential surface of the first expansion valve.
The compressor may include a linear compressor.
The first evaporator may be an evaporator used for cooling cool air supplied into the deep-freezing storage chamber.
The refrigerator may further include at least one additional evaporator for cooling one or all of the refrigerating compartment and the freezing compartment and at least one additional expansion valve connected to an inlet-side of the at least one additional evaporator.
The first expansion valve and the at least one additional expansion valve may be connected in parallel to each other, and the refrigerator may further include a switching valve disposed on a position at which the first and additional expansion valves are branched to switch a flow direction of the refrigerant.
Fig. 1 is a view illustrating a refrigeration cycle of a refrigerator according to one embodiment.
Referring to Fig. 1, a refrigeration cycle 10 of a refrigerator according to one embodiment includes a compressor 11 compressing a refrigerant into a high-temperature high-pressure gas state; a condenser 12 disposed on an outlet-side of compressor 11 to phase-change the high-temperature high-pressure gas refrigerant into a high-temperature high-pressure liquid refrigerant; expansion valves 14 and 15 disposed on an outlet-side of condenser 12 to expand the high-temperature high-pressure liquid refrigerant cooled by passing through condenser 12, thereby changing the high-temperature high-pressure liquid refrigerant into a low-temperature low-pressure two-phase refrigerant; and evaporators 16 and 17 respectively disposed on outlet-sides of expansion valves 14 and 15 to phase-change the low-temperature low-pressure two-phase refrigerant which is changed in phase by passing through expansion valves 14 and 15 into a low-temperature low-pressure liquid refrigerant.
Specifically, compressor 11 may include a linear compressor. Alternatively, compressor 11 may include a fixed speed or inverter compressor. When compressor 11 includes a linear compressor, compressor 11 is controlled so that a top dead center operation is performed in a deep-freezing cooling process.
Generally, the condenser 12 may be accommodated in a machine room disposed in a rear side of the refrigerator to release heat to the ambient air (e.g., indoor air). Also, a switching valve 13 including a three-way valve may be disposed between condenser 12 and the expansion valves 14 and 15. Switching valve 13 is used for switching a flow direction of the refrigerant in a structure in which main evaporator 16 is used for cooling the refrigerating compartment, and the freezing compartment and deep-freezing evaporator 17 is used for cooling the deep-freezing storage chamber and are connected to parallel to each other. Here, the three-way valve or a four-way valve may be used according to the number of evaporators. For example, when one main evaporator is used, and thus a cool air passage connecting the refrigerating compartment to the freezing compartment is switched to independently control a temperature of each of the storage compartments, the three-way valve may be used. On the other hand, in a structure in which an evaporator for the refrigerating compartment, an evaporator for the freezing compartment, and an evaporator for the deep-freezing evaporator are separately provided and connected parallel to each other, the four-way valve may be applied to switch the flow direction of the refrigerant.
One exemplary embodiment in which one main evaporator 16 is used to cool the refrigerating compartment and the freezing compartment, and a separate deep-freezing evaporator 17 is used for cooling the deep-freezing storage chamber and is parallely connected to main evaporator 16 will be described. Thus, main expansion valve 15 and deep-freezing expansion valve 14 may be respectively disposed on inlet-sides of the main evaporator 16 and the deep-freezing evaporator 17, and the expansion valves 14, 15 are connected in parallel with each other at the outlet-side of the switching valve 13.
A separate heater 18 may be mounted on an outer circumferential surface of deep-freezing expansion valve 14 to reduce a temperature of the refrigerant passing through deep-freezing expansion valve 14 to a temperature lower than that of the freezing compartment. Heater 18 is operated in an operation mode for cooling the deep-freezing storage chamber. When the deep-freezing storage chamber is cooled to a set temperature, the heater 18 may be stopped in operation.
Also, a condensation fan (not shown) and an evaporation fan (not shown) may be respectively mounted outside condenser 12 and evaporators 16 and 17 to heat-exchange the indoor air with the refrigerant or air within the storage chamber with the refrigerant.
Fig. 2 is a p-h diagram for comparing the refrigeration cycle according to an embodiment to a general refrigeration cycle according to a related art.
Referring to Fig. 2, in the general refrigeration cycle according to the related art, and compression, condensation, expansion, and evaporation are performed in an order of points a, b, c, and d.
On the other hand, in the refrigeration cycle according to an embodiment of the present disclosure, i.e., the refrigeration cycle including heater 18 on the outer circumferential surface of deep-freezing expansion valve 14, compression, condensation, expansion, and evaporation are performed in an order of points e, f, c, and g.
As shown in the p-h diagram, when heater 18 mounted on deep-freezing expansion valve 14 is driven, the refrigerant passing through deep-freezing expansion valve 14 may be dropped to an evaporation pressure lower than that in the refrigerant cycle according to the related art. Specifically, since the evaporation pressure is lowered, the evaporation temperature is lowered. Thus, since the evaporation temperature is lowered, cool air within the deep-freezing storage chamber may be lowered in temperature to less than that of cool air according to the related art.
The general refrigeration cycle according to the related art in the p-h diagram of Fig. 2 represents a cycle diagram when any heat-exchange member is not provided to the expansion valve. In a case of a structure in which a suction pipe is heat-exchanged with the expansion valve, heat may be transferred from the refrigerant passing through the expansion valve to the refrigerant passing through the suction pipe, an amount of gas refrigerant of the refrigerant introduced into the compressor may be increased. Then, the refrigerant passing through the expansion valve may be decreased in temperature. Thus, an enthalpy line (a c-d line) of the refrigerant may be further shifted to the left in the p-h diagram. As a result, an enthalpy valve of the refrigerant at an inlet of the evaporator may be decreased. That is, an amount of heat absorbed into the evaporator may be increased to increase cooling capacity. However, although the heat exchange may be performed through the suction pipe, since the evaporation pressure is not changed, it may be difficult to further reduce the temperature of the cool air within the deep-freezing storage chamber even though the cooling capacity is increased.
Also, in a case where the deep-freezing expansion valve has a diameter less than that of the main expansion valve, a refrigerant state point (e.g., point d) when the expansion is completed, i.e., an evaporation pressure at the inlet of the deep-freezing evaporator may be further decreased, and also, an enthalpy valve at the deep-freezing evaporator may be increased. That is, in the p-h diagram, the point d may be shifted down and to the right. As a result, the refrigerant may be further decreased in temperature to decrease the temperature of the deep-freezing storage chamber. However, due to the decrease in the temperature of the deep-freezing storage chamber, an amount of refrigerant which is changed in phase from the liquid refrigerant to the gas refrigerant in the refrigerant passing through the evaporator may be reduced. That is, if it is assumed that the refrigerant passing through the evaporator absorbs energy having the same heat from the indoor air, an amount of refrigerant which is changed in phase from the liquid refrigerant to the gas refrigerant may be reduced. This may represent the reduction in a saturation achievement rate of the refrigerant. As a result, possibility of the introduction of the liquid refrigerant into the compressor may be further increased.
As proposed in one embodiment, when heater 18 is mounted on the surface of deep-freezing expansion valve 14, outlet point d of the deep-freezing expansion valve (or the outlet point of the deep-freezing evaporator) may be moved to point g in an ideal state. In an actual refrigeration cycle, point g may be located at a point that is further shifted to the right.
If it is assumed that the evaporator absorbs the energy having the same heat, quality of the refrigerant at the inlet of the compressor, i.e., quality of the refrigerant at an inlet of a gas/liquid separator may be further increased in the current embodiment when compared to the case in which the expansion valve is changed in diameter. This may represent that the saturation achievement rate of the refrigerant is not reduced. Thus, the possibility of the introduction of the liquid refrigerant into the compressor may be significantly decreased.
As described above, since heater 18 provided in one embodiment is attached to deep-freezing expansion valve 17, the evaporation temperature and pressure of the refrigerant passing through deep-freezing expansion valve 17 may be significantly reduced when compared to those of a refrigerant in the related art. Thus, the deep-freezing storage chamber may be cooled to a temperature significantly lower than that of the freezing compartment. That is to say, although a refrigerant passing through the expansion valve to which the heater is not mounted is lowered to a temperature of about -40°C, the refrigerant passing through the expansion valve to which the heater is mounted may be lowered to a temperature of a maximum -50°C.
According to the method for controlling the refrigerator including the above-described constitutions, the separate heater may be provided to the expansion valve connected to the inlet-side of the evaporator for the deep-freezing storage chamber to further decrease the evaporator pressure when compared to that in the related art. Thus, the evaporator may be lowered up to a temperature of a maximum -50°C. In addition, the deterioration in the saturation achievement rate of the refrigerant which occurs when the expansion valve is changed in diameter may not occur, preventing the compressor from being degraded in performance or damaged.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the scope of the principles of this disclosure. More particularly, variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

Claims

A refrigerator comprising:
a main body comprising a refrigerating compartment configured to be maintained at a temperature higher than a freezing temperature and a freezing compartment configured to be maintained at a temperature lower than the freezing temperature;

a deep-freezing storage chamber disposed within the main body, the deep-freezing storage chamber being configured to be maintained at a temperature lower than that of the freezing compartment;

a compressor (11) for compressing a refrigerant at a high temperature and a high pressure;

a condenser (12) connected to an outlet-side of the compressor to condense the high-temperature high-pressure refrigerant;

a first expansion valve (14) connected to an outlet-side of the condenser to expand the refrigerant so that the refrigerant has a low-temperature low-pressure two-phase state;

a first evaporator (17) connected to an outlet-side of the first expansion valve to change the refrigerant into a low-temperature low-pressure gas refrigerant; and

a heater (18) disposed outside the first expansion valve, for supplying heat into the first expansion valve (14) to lower an evaporation temperature of the refrigerant to a temperature lower than that of the freezing compartment.
The refrigerator of claim 1, wherein the heater (18) is disposed in such a manner that the heater contacts an outer circumferential surface of the first expansion valve (14).
The refrigerator of claim 1 or 2, wherein the compressor (11) comprises a linear compressor.
The refrigerator of any of claims 1 to 3, wherein the first evaporator (17) is configured for cooling cool air supplied into the deep-freezing storage chamber.
The refrigerator of any of preceding claims, further comprising:
at least one additional evaporator (16) for cooling one or all of the refrigerating compartment and the freezing compartment; and

at least one additional expansion valve (15) connected to an inlet-side of the at least one additional evaporator.
The refrigerator of claim 5, wherein the first expansion valve (14) and the at least one additional expansion valve (15) are connected in parallel to each other, and
the refrigerator further comprises:
a switching valve (13) disposed on a position at which the first and the at least one additional expansion valves (14, 15) are branched, so as to switch a flow direction of the refrigerant.