Cooling cycle

Abstract

A cooling cycle according to an embodiment of the present invention may include: a compressor for compressing a refrigerant; a condenser connected to the outlet side of the compressor for condensing the refrigerant; an expansion valve connected to the outlet side of the condenser for expanding the refrigerant; an evaporator connected to the outlet side of the expansion valve for evaporating the refrigerant; refrigerant piping connecting the compressor, the condenser, the expansion valve, and the evaporator; and a thermoelectric module that absorbs heat from the refrigerant flowing along the inlet side piping of the evaporator and transfers it to the refrigerant flowing along the outlet side piping of the evaporator.

Description

Technology Field

[0001] The present invention relates to a cooling cycle. Background Technology

[0002] Generally, cooling cycles are installed in refrigerators or air conditioners and are used to maintain the temperature of indoor air lower or higher than the outdoor temperature.

[0003] The cooling cycle includes a refrigerant, a compressor that compresses the refrigerant to a high temperature and high pressure, a condenser that condenses the refrigerant into a liquid state, an expansion valve that expands the refrigerant into a two-phase state, an evaporator that evaporates the refrigerant into a gaseous state, and refrigerant piping that connects these components to form a closed circuit.

[0004] The efficiency (COP) of a cooling cycle is defined as the ratio of the cooling capacity of the evaporator—that is, the amount of heat absorbed by the evaporator—to the work (P) input by the compressor to compress the refrigerant.

[0005] If a small amount of energy is input into the compressor to absorb a large amount of heat from the evaporator, the efficiency of the cooling cycle increases, and as a result, an improvement in energy consumption can be achieved for products that use the cooling cycle as a component.

[0006] In this way, various types of cooling cycles have been studied to maximize heat absorption in the evaporator without increasing the work input into the compressor.

[0007] For example, the cooling cycle disclosed in the prior art below shows that a so-called condensing pipe connecting a condenser and an evaporator and a so-called suction pipe connecting an evaporator and a compressor are in direct contact, so that heat exchange through heat conduction is performed between the refrigerant flowing along the condensing pipe and the refrigerant flowing along the suction pipe.

[0008] Additionally, it shows that the suction piping is connected to the expansion valve in a heat-conducting manner to enable two-stage heat exchange.

[0009] The refrigerant flowing along the condensation pipe is a high-temperature, high-pressure liquid refrigerant, and the refrigerant flowing along the suction pipe is a low-temperature, low-pressure gaseous refrigerant. Accordingly, heat is transferred from the high-temperature refrigerant flowing along the condensation pipe to the low-temperature refrigerant flowing along the suction pipe. As a result, the temperature of the gaseous refrigerant flowing along the suction pipe becomes supersaturated before it flows into the compressor.

[0010] In addition, as the refrigerant passes through the expansion valve, it releases a large amount of heat, causing the high-temperature, high-pressure liquid refrigerant to undergo a phase change into a low-temperature, low-pressure two-phase refrigerant. Then, the heat released from the expansion valve is transferred to the refrigerant flowing along the suction pipe.

[0011] According to the cooling cycle disclosed in the prior art above, the temperature at the evaporator inlet is reduced, so the amount of heat that can be absorbed by the evaporator increases, thereby obtaining the effect of increasing the efficiency of the cycle.

[0012] However, because the structure involves contact between refrigerant pipes, significant heat loss occurs during the heat exchange process, which has the disadvantage of limiting the ability to lower the evaporator inlet temperature. Prior art literature

[0013] Korean Patent Publication No. 10-2007-0089260 (August 30, 2007) The problem to be solved

[0014] The present invention is proposed to improve upon the problems mentioned above.

[0015] Specifically, the purpose is to provide a cooling cycle capable of minimizing heat loss during the process of heat transfer from the refrigerant pipe at the evaporator inlet to the refrigerant pipe at the evaporator outlet. means of solving the problem

[0016] A cooling cycle according to an embodiment of the present invention for achieving the above-mentioned purpose may include: a compressor for compressing a refrigerant; a condenser connected to the outlet side of the compressor for condensing the refrigerant; an expansion valve connected to the outlet side of the condenser for expanding the refrigerant; an evaporator connected to the outlet side of the expansion valve for evaporating the refrigerant; refrigerant piping connecting the compressor, the condenser, the expansion valve, and the evaporator; and a thermoelectric module that absorbs heat from the refrigerant flowing along the inlet side piping of the evaporator and transfers it to the refrigerant flowing along the outlet side piping of the evaporator. Effects of the invention

[0017] According to the cooling cycle according to the embodiment of the present invention having the above configuration, the following effects are achieved.

[0018] Specifically, the evaporator inlet piping and the evaporator outlet piping are connected to enable mutual heat transfer by a thermoelectric module, thereby minimizing heat loss during the heat conduction process. In addition, by involving the thermoelectric module, an energy improvement effect can be obtained in which the efficiency (COP) of the cooling cycle increases by at least 5% compared to the conventional method.

[0019] In addition, since heat is absorbed from the refrigerant flowing along the piping on the evaporator inlet side at the heat-absorbing surface of the thermoelectric module with almost no heat loss, the cooling power of the evaporator in the cooling cycle of the present invention can be increased by 10% to 20% compared to the cooling power of the evaporator in a conventional cooling cycle.

[0020] Furthermore, there is an advantage in that the cooling reliability of a cooling product, such as a refrigerator or an indoor unit of an air conditioner, equipped with a cooling cycle according to an embodiment of the present invention is ensured. Brief explanation of the drawing

[0021] FIG. 1 is a configuration diagram of a cooling cycle according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of a thermoelectric module provided in a cooling cycle according to an embodiment of the present invention. FIG. 3 is a pH diagram of a cooling cycle according to an embodiment of the present invention. Figure 4 is a graph showing the relationship between input voltage and the Fourier effect of cooling power. Figure 5 is a graph showing the efficiency relationship with respect to input voltage and Fourier effect. Figure 6 is a graph showing the correlation between cooling power and efficiency according to voltage. FIG. 7 is a configuration diagram of a cooling cycle according to another embodiment of the present invention. FIG. 8 is a configuration diagram of a cooling cycle according to another embodiment of the present invention. FIG. 9 is a configuration diagram of a cooling cycle according to another embodiment of the present invention. Specific details for implementing the invention

[0022] Hereinafter, a cooling cycle according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0023] FIG. 1 is a diagram showing the configuration of a cooling cycle according to an embodiment of the present invention.

[0024] Referring to FIG. 1, a cooling cycle (10) according to an embodiment of the present invention may include a compressor (11), a condenser (12), an expansion valve (14), an evaporator (15), a thermoelectric module (20), and a refrigerant pipe (18) that connects the components to form a refrigerant circulation circuit.

[0025] Additionally, a condensing fan (121) may be placed on one side of the condenser (12), and an evaporating fan (151) may be placed on one side of the evaporator (15).

[0026] In detail, the compressor (11) compresses the gas phase refrigerant at low temperature and low pressure to high temperature and high pressure, and the condenser (12) changes the gas phase refrigerant at high temperature and high pressure into a liquid phase refrigerant at high temperature and high pressure.

[0027] The expansion valve (14) expands the high-temperature, high-pressure liquid refrigerant into a low-temperature, low-pressure two-phase refrigerant, and the evaporator (15) changes the low-temperature, low-pressure two-phase refrigerant into a low-temperature, low-pressure gaseous refrigerant.

[0028] Meanwhile, the inlet pipe (181) connecting the outlet end of the expansion valve (14) and the inlet end of the evaporator (15) is connected to the heat-absorbing surface of the thermoelectric module (20) so as to conduct heat.

[0029] And, the outlet pipe (182) extending from the outlet end of the evaporator (15) is connected to the heat-generating surface of the thermoelectric module (20) so as to conduct heat.

[0030] And, when power is applied to the thermoelectric module (20) along with the operation of the compressor (11), heat released from the inlet pipe (181) is transferred to the outlet pipe (182) through the thermoelectric module (20).

[0031] Here, in the case of a refrigerator in which the cooling cycle for the refrigerator compartment and the cooling cycle for the freezer compartment are provided independently, the cooling cycles described above are installed respectively; however, the sizes of the evaporators for the refrigerator compartment and the freezer compartment, as well as the capacities of the compressors for the refrigerator compartment and the freezer compartment, are set differently. Therefore, a separate explanation regarding the structure in which two cooling cycles are provided independently will be omitted.

[0032] FIG. 2 is an exploded perspective view of a thermoelectric module provided in a cooling cycle according to an embodiment of the present invention.

[0033] Referring to FIG. 2, a thermoelectric module (20) provided in a cooling cycle (10) according to an embodiment of the present invention may include a thermoelectric element (24) (or a Peltier element), a cold sink (22) in contact with one side of the thermoelectric element (24), a heat sink (25) in contact with the other side of the thermoelectric element (24), an insulator (23) that surrounds the edge of the thermoelectric element (24) to block heat transfer between the cold sink (22) and the heat sink (25), and a case that accommodates the components.

[0034] In detail, the thermoelectric element (24) may include a heat absorption surface (241), a heat generation surface (242), and a semiconductor layer (243) interposed between them. When power is applied to the thermoelectric element (24), the temperature of the heat absorption surface (241) decreases and the temperature of the heat generation surface (242) increases. The heat absorbed through the heat absorption surface (241) flows to the heat generation surface (242) through the semiconductor layer (243). Since the detailed configuration and function of the thermoelectric element (24) are already widely known to those skilled in the art, a detailed description thereof is omitted.

[0035] The above case may include a front case (21) and a rear case (26), and either the front case (21) or the rear case (26) may be defined as a first case and the other as a second case.

[0036] Inside the above cold sink (22), a guide channel for guiding the flow of refrigerant may be formed in a zigzag shape, a meander line, or an S-line, and the inlet side pipe (181) may be connected to the inlet and outlet of the guide channel, respectively.

[0037] In other words, the inlet piping (181) may include a pipe connecting the outlet of the expansion valve (14) and the inlet of the guide path, and a pipe connecting the outlet of the guide path and the inlet of the evaporator (15).

[0038] Accordingly, the refrigerant passing through the expansion valve (14) flows along the guide path inside the cold sink (22) and exchanges heat with the heat-absorbing surface (241) of the thermoelectric element (24).

[0039] Similar to the cold sink above, a winding guide channel is formed inside the heat sink (25), and a heating side pipe (182) can be connected to the inlet and outlet of the guide channel.

[0040] Figure 3 is a pH diagram of a cooling cycle according to an embodiment of the present invention.

[0041] Referring to FIGS. 2 and 3, first, the low temperature (T) sucked in through the suction end (①) of the compressor (11) c ) / Low pressure(P c The gaseous refrigerant of ) is compressed by the operation of the compressor (11), and the gaseous refrigerant of high temperature (Th) / high pressure (Ph) is discharged to the outlet (②) of the compressor.

[0042] The high-temperature / high-pressure gaseous refrigerant that has passed through the compressor (11) is cooled as it passes through the condenser (12) and is discharged to the outlet (③) of the condenser (12) in the state of high-temperature / high-pressure liquid refrigerant.

[0043] In addition, the refrigerant that has passed through the condenser (12) is expanded into a low-temperature / low-pressure two-phase refrigerant through the expansion valve (14).

[0044] And, the low-temperature / low-pressure two-phase refrigerant that has passed through the expansion valve (14) passes through the cold sink (22) of the thermoelectric module (20) and exchanges heat with the heat-absorbing surface (241) of the thermoelectric element (24).

[0045] In detail, the temperature of the refrigerant discharged to the outlet end (④) of the expansion valve (14) and flowing along the inlet pipe (181) is low, but higher than the temperature of the heat-absorbing surface (241) of the thermoelectric element (24). Therefore, heat is transferred from the cold sink (22) to the heat-absorbing surface (241), and the quality of the refrigerant at the outlet end of the cold sink (22) or the inlet end (⑤) of the evaporator (15) is lower than the quality of the refrigerant under conditions without the thermoelectric module (20). In other words, the amount of refrigerant undergoing a phase change to a liquid state increases.

[0046] More specifically, depending on the voltage applied to the thermoelectric module (20), the temperature of the refrigerant at the inlet end of the evaporator (15) is low pressure (P c Maintain the saturated liquid refrigerant temperature at ), but if the dryness decreases or low pressure (P c It can become a supersaturated liquid refrigerant state at a temperature lower than the saturated liquid refrigerant temperature at ).

[0047] Theoretically, the amount of heat taken away by the heat absorption surface (241) of the thermoelectric element (21) is a first additional amount of heat (Q) that can be absorbed until the state of the refrigerant flowing into the inlet end of the evaporator (15) becomes the temperature and dryness value of the refrigerant measured at the inlet end of the evaporator under conditions without a thermoelectric module. t1 It can be understood as ).

[0048] In addition, as the refrigerant passes through the evaporator (15), the so-called basic heat quantity (Q) that can be absorbed under conditions without the thermoelectric module (20) c After absorbing ), it is discharged to the outlet end (⑥) of the evaporator (15).

[0049] And, the refrigerant flowing along the outlet pipe (182) of the evaporator (15, 17) absorbs heat as it passes through the heat sink (25) of the thermoelectric module (20). That is, at least a portion (Q) of the heat absorbed from the refrigerant flowing along the inlet pipe (181) through the thermoelectric element (24)t2 ) is transferred to the heat sink (25) and absorbed by the refrigerant passing through the heat sink (25). Here, the amount of heat absorbed by the refrigerant while passing through the heat sink (25) is the second additional heat amount (Q t2 It can be defined as ).

[0050] The above second additional heat quantity (Q t2 Depending on the size of ), the refrigerant at the inlet (①) of the compressor (11) (or the outlet (⑦) of the heat sink (25) is at a low pressure (P c It can exist as a saturated gas or a supersaturated gas at a higher temperature.

[0051] In this way, the inlet pipe (181) and the outlet pipe (182) of the evaporator (15) are connected to enable heat transfer by the thermoelectric module (20), thereby allowing the evaporator (15) to absorb a basic amount of heat (Q) that the evaporator (15) can absorb under conditions where the thermoelectric module (20) is not provided. c In addition to ), the above first and second additional heat quantities (Q t1 ,Q t2 It can be seen that it can absorb more of ).

[0052] In addition, as the temperature of the refrigerant increases at the inlet side of the compressor (11), the amount of input work (Pc) required for the compressor (11) to compress the refrigerant to a high temperature / high pressure state may be reduced.

[0053] Meanwhile, the efficiency (COP) of the refrigeration cycle can be defined by the following equation.

[0054] ,

[0055] ,

[0056] ,

[0057] From the above equation, compared to a cooling cycle without a thermoelectric module (20), the total cooling power (Qi) in the numerator of the refrigeration cycle (10) according to the embodiment of the present invention has been increased by an amount corresponding to the first and second additional cooling powers, and the total input work (P) in the denominator e ) is the amount of power (or energy) supplied to the thermoelectric element (P e It increased by )

[0058] However, since the increase in cooling power is greater than the increase in input power, the efficiency (COP) of the refrigeration cycle increases, and as a result of actual experiments, it was confirmed that the cooling power increased by about 10% to 20% compared to the cooling power of a conventional cooling cycle without a thermoelectric module (20), and the efficiency increased by at least 5%.

[0059] The efficiency and cooling power of thermoelectric elements are explained below.

[0060] The efficiency of the thermoelectric module (20) can be defined by the coefficient of performance (COP), and the efficiency formula is as follows.

[0061]

[0062] Q c : Cooling Capacity (ability to absorb heat)

[0063] P e : Input (Input Power, power supplied to the thermoelectric element)

[0064] P e = V × i

[0066] In addition, the cooling power of the thermoelectric module (20) can be defined as follows.

[0067]

[0069] <Semiconductor Material Characteristic Coefficients>

[0070] α: Seebeck coefficient [V / K]

[0071] ρ: Resistivity [Ωm⁻¹]

[0072] k: Thermal conductivity [W / mk]

[0073] Semiconductor Structure Characteristics

[0074] L: Thermoelectric element thickness : Distance between the heat-absorbing surface and the heat-generating surface

[0075] A: Area of ​​the thermoelectric element

[0076] <System Usage Conditions>

[0077] i: current

[0078] V: Voltage

[0079] Th: Temperature of the heating surface of the thermoelectric element

[0080] Tc: Temperature of the heat-absorbing surface of the thermoelectric element

[0082] In the above cooling equation, the first term on the right can be defined as the Peltier effect and as the amount of heat transferred between the ends of the heat-absorbing surface and the heat-exciting surface due to the voltage difference. Furthermore, the Peltier effect increases in proportion to the supply current as a function of current.

[0083] In the equation V = iR, the semiconductor constituting the thermoelectric element acts as a resistor, and since the resistor can be considered a constant, it can be said that voltage and current are in a proportional relationship. That is, it means that if the voltage applied to the thermoelectric element (21) increases, the current also increases. Therefore, the Peltier effect can be viewed as a function of current or as a function of voltage.

[0084] Furthermore, the aforementioned cooling power can also be viewed as a function of current or voltage. Additionally, the Peltier effect acts as a positive effect that increases the cooling power. In other words, as the supply voltage increases, the Peltier effect increases, thereby increasing the cooling power.

[0085] And, the second term in the above cooling equation is defined as the Joule effect.

[0086] The above Joule effect refers to the effect where heat is generated when current is applied to a resistor. In other words, since heat is generated when power is supplied to a thermoelectric element, this acts as a negative effect that reduces cooling power. Therefore, if the voltage supplied to the thermoelectric element increases, the Joule effect increases, resulting in a decrease in the cooling power of the thermoelectric element.

[0087] In the above cooling equation, the third term is defined as the Fourier Effect.

[0088] The above Fourier effect refers to the effect where heat is transferred by heat conduction when a temperature difference occurs between the two sides of a thermoelectric element.

[0089] Specifically, the thermoelectric element comprises a heat-absorbing surface and a heat-generating surface made of a ceramic substrate, and a semiconductor disposed between the heat-absorbing surface and the heat-generating surface. When a voltage is applied to the thermoelectric element, a temperature difference occurs between the heat-absorbing surface and the heat-generating surface. Heat absorbed through the heat-absorbing surface passes through the semiconductor and is transferred to the heat-generating surface. However, when a temperature difference occurs between the heat-absorbing surface and the heat-generating surface, a phenomenon occurs in which heat flows back from the heat-generating surface to the heat-absorbing surface due to thermal conduction; this is called the Fourier effect.

[0090] The above Fourier effect acts as a negative effect that reduces cooling power, just like the Joule effect. In other words, as the temperature difference (Th-Tc) between the heat-generating and heat-absorbing surfaces of the thermoelectric element—that is, the value of ΔT—increases, heat backflow due to heat conduction increases, resulting in a decrease in cooling power.

[0091] Figure 4 is a graph showing the relationship between the input voltage and the Fourier effect of the cooling power.

[0092] Referring to Fig. 4, the Fourier effect can be defined as a function of the temperature difference between the endothermic and exothermic surfaces, i.e., ΔT.

[0093] In detail, once the specifications of the thermoelectric element are determined, the values ​​of k, A, and L in the Fourier effect term of the above cooling equation become constant values, so the Fourier effect can be viewed as a function with ΔT as a variable.

[0094] Therefore, as ΔT increases, the Fourier effect value increases, but since the Fourier effect acts as a negative effect on cooling power, the cooling power eventually decreases.

[0095] As shown in the graph of Figure 4, under constant voltage conditions, it can be seen that the larger ΔT is, the less cooling power is produced.

[0096] In addition, if we examine the change in cooling power according to the change in voltage by limiting the case to a fixed state of ΔT, for example, when ΔT is 30℃, the cooling power increases as the voltage value increases, then reaches a peak at a certain point, and then decreases again, forming a parabolic shape.

[0097] It should be noted that since voltage and current are in a proportional relationship, it is acceptable to treat the current listed in the above cooling formula as voltage and interpret it in the same way.

[0098] Specifically, as the supply voltage (or current) increases, the cooling power increases, which can be explained by the cooling power formula above. First, since the above ΔT value is fixed, it becomes a constant. Since the above ΔT value is determined according to the specifications of the thermoelectric element, the appropriate specifications of the thermoelectric element can be set according to the required ΔT value.

[0099] And, since ΔT is fixed, the above Fourier effect can be viewed as a constant, and ultimately, the cooling power can be simplified into a function of the Peltier effect, which can be viewed as a linear function of voltage (or current), and the Joule effect, which can be viewed as a quadratic function of voltage (or current).

[0100] And, as the voltage value gradually increases, the increase in the Peltier effect, which is a linear function of voltage, is greater than the increase in the Joule effect, which is a quadratic function of voltage, and consequently, the cooling power increases. In other words, until the cooling power reaches its maximum, the function of the Joule effect is close to a constant, so the cooling power approaches the linear function of voltage.

[0101] Furthermore, as the voltage increases, an inversion occurs where the self-heating amount due to the Joule effect becomes greater than the heat transferred due to the Peltier effect, and as a result, it can be observed that the cooling power decreases again. This can be understood more clearly from the functional relationship between the Peltier effect, which is a linear function of voltage (or current), and the Joule effect, which is a quadratic function of voltage (or current). In other words, when the cooling power decreases, the cooling power takes a form that approaches a quadratic function of voltage.

[0102] In the graph of Figure 4, it can be seen that the cooling power is maximum when the supply voltage is in the range of approximately 30 to 40 V, more specifically at approximately 35 V. Therefore, if only cooling power is considered, it can be said that it is desirable to have a voltage difference within the range of 30 to 40 V in the thermoelectric element.

[0103] Figure 5 is a graph showing the efficiency relationship with respect to input voltage and Fourier effect.

[0104] Referring to Figure 5, it can be seen that the efficiency is lower as ΔT increases relative to the same voltage. This is a natural result, as efficiency is proportional to cooling power.

[0105] In addition, if we examine the change in efficiency according to voltage change while limiting the case to a fixed ΔT, for example, when ΔT is 30℃, the efficiency increases as the supply voltage increases, but after a certain point, the efficiency actually decreases. This can be said to be similar to the cooling power graph according to voltage change.

[0106] Here, the efficiency (COP) is a function of not only the cooling power but also the input power, and the input (Pe) is V, where the resistance of the thermoelectric element (21) is considered as a constant. 2 It becomes a function of. And, the cooling power is V 2 If divided by, efficiency ultimately, It can be represented as such. Therefore, the graph of the above efficiency can be seen to have the shape shown in Fig. 5.

[0107] It can be seen from the graph in Fig. 5 that the point where efficiency is maximum occurs in the region where the voltage difference (or supply voltage) applied to the thermoelectric element is approximately less than 20V. Therefore, once the required ΔT is determined, it is advisable to apply an appropriate voltage accordingly to maximize efficiency. That is, once the temperature of the heat sink and the set temperature of the deep temperature chamber (202) are determined, ΔT is determined, and accordingly, the optimal voltage difference applied to the thermoelectric element can be determined.

[0108] Figure 6 is a graph showing the correlation between cooling power and efficiency according to voltage.

[0109] Referring to Figure 6, as described above, as the voltage difference increases, both cooling power and efficiency increase and then decrease.

[0110] In detail, it can be seen that the voltage value at which cooling power is maximized and the voltage value at which efficiency is maximized are different. This can be attributed to the fact that the cooling power is a linear function of voltage until it is maximized, while the efficiency is a quadratic function of voltage.

[0111] As shown in Fig. 6, for example, in the case of a thermoelectric element with ΔT of 30°C, it can be seen that the efficiency of the thermoelectric element is highest when the voltage difference applied to the thermoelectric element is in the range of approximately 12V to 17V. Furthermore, within the above voltage range, the cooling power continues to increase. Therefore, considering the cooling power, a voltage difference of at least 12V is required, and it can be seen that the efficiency is maximum when the voltage difference is 14V.

[0112] FIG. 7 is a configuration diagram of a cooling cycle according to another embodiment of the present invention.

[0113] Referring to FIG. 7, the cooling cycle (10a) according to the present embodiment is characterized in that two expansion valves (14, 16) are connected in parallel by a three-way valve (13), and an evaporator (15, 17) is connected to the outlet side of each of the two expansion valves (14, 16).

[0114] And, a thermoelectric module (20) according to the present invention is connected to each of the two evaporators (15, 17).

[0115] One of the two evaporators (15, 17) can be understood as a refrigerator evaporator and the other as a freezer evaporator.

[0116] And, one of the two expansion valves (14, 16) can be understood as a refrigerator expansion valve and the other as a freezer expansion valve.

[0117] And, the inlet pipe (181) connecting the outlet end of the expansion valve (14, 16) and the inlet end of the evaporator (15, 17) is connected to the heat-absorbing surface of the thermoelectric module (20) so as to conduct heat.

[0118] And, the outlet pipe (182) extending from the outlet end of the evaporator (15, 17) is connected to the heat-generating surface of the thermoelectric module (20) so as to conduct heat.

[0119] The thermoelectric module (20) connected to the inlet and outlet pipes of the first evaporator can be defined as the first thermoelectric module, and the thermoelectric module (20) connected to the inlet and outlet pipes of the second evaporator can be defined as the second thermoelectric module.

[0120] FIG. 8 is a diagram of a cooling cycle according to another embodiment of the present invention.

[0121] Referring to FIG. 8, the cooling cycle (10b) according to the present embodiment may include a compressor (11), a condenser (12), a condensing fan (121), an expansion valve (14), a pair of evaporators (15, 17) connected in series, evaporator fans (151, 171) each mounted on one side of the pair of evaporators (15, 17), an inlet pipe (181) connecting the outlet of the expansion valve (14) and the inlet of one of the pair of evaporators (15, 17), an outlet pipe extending from the other outlet of the pair of evaporators (15, 17), and a thermoelectric module (20) connected to the inlet pipe (181) and the outlet pipe (182) for heat exchange.

[0122] In detail, the evaporator (15) connected to the inlet pipe (181) is defined as the first evaporator, and the evaporator (17) connected to the outlet of the first evaporator can be defined as the second evaporator.

[0123] And, either of the first evaporator and the second evaporator mentioned above can be understood as a freezer evaporator and the other as a refrigerator evaporator.

[0124] And, the structure in which the cold sink (22) of the thermoelectric module (20) is connected to the inlet side pipe (181) and the outlet side pipe (182) is connected to the heat sink (25) is the same as described in FIG. 2.

[0125] According to the present embodiment, the low-temperature, low-pressure two-phase refrigerant that has passed through the expansion valve (14) flows into the first evaporator while passing through the cold sink (22) with a further decrease in dryness.

[0126] And, the two-phase refrigerant, which has a higher dryness level by absorbing heat while passing through the first evaporator and the second evaporator in sequence, further absorbs heat transferred from the cold sink (22) while passing through the heat sink (25) and undergoes a phase change into a saturated gas or supersaturated gas state.

[0127] And, the low-temperature, low-pressure refrigerant that has undergone a phase change to a saturated gas or supersaturated gas state flows into the compressor (11).

[0128] FIG. 9 is a diagram of a cooling cycle according to another embodiment of the present invention.

[0129] Referring to FIG. 9, the cooling cycle (10c) according to the present embodiment has a structure consisting of a compressor (11), a condenser (12), a condensing fan (121), an expansion valve (14), an evaporator (15, 17), an evaporating fan (151, 171), and a thermoelectric module (20), which is the same as the embodiment presented in FIG. 8.

[0130] That is, the two evaporators (15, 17) are connected in series, and the evaporator (15) on the front side can be defined as the first evaporator, and the evaporator (17) on the rear side can be defined as the second evaporator.

[0131] Also, the structure is the same in that the inlet pipe (181) connecting the expansion valve (14) and the first evaporator is connected to the cold sink (22) of the thermoelectric module (20), and the outlet pipe (182) connected to the outlet of the second evaporator is connected to the heat sink (25) of the thermoelectric module (20).

[0132] However, there is a difference in that a bypass valve (19) is installed at a certain point of the outlet-side pipe (182) extending from the outlet of the cold sink (22), and a bypass pipe (183) extends from the bypass valve (19) and is joined at a certain point of the refrigerant pipe (18) connecting the outlet of the first evaporator and the inlet of the second evaporator.

[0133] According to the cooling cycle (10c) of the present embodiment, in a refrigeration and freezing simultaneous operation mode, the refrigerant is allowed to flow sequentially to the first and second evaporators.

[0134] However, in a standalone operation mode where only the second evaporator is operated, the entire refrigerant can be allowed to flow into the bypass pipe (183) by operating the bypass valve (19).

[0135] However, regardless of which operating mode the refrigerator is operated in, the refrigerant exchanges heat (releases heat) through the cold sink (22) of the thermoelectric module (20) before flowing into the evaporator, absorbs heat in the first stage while passing through the evaporator, and then absorbs heat in the second stage through the heat sink (25) of the thermoelectric module (20).

Claims

Claim 1 A cooling cycle comprising: a compressor for compressing refrigerant; a condenser connected to the outlet side of the compressor for condensing refrigerant; an expansion valve connected to the outlet side of the condenser for expanding refrigerant; an evaporator connected to the outlet side of the expansion valve for evaporating refrigerant; refrigerant piping connecting the compressor, condenser, expansion valve, and evaporator; and a thermoelectric module that absorbs heat from refrigerant flowing along the inlet side piping of the evaporator and transfers it to refrigerant flowing along the outlet side piping of the evaporator, wherein the thermoelectric module comprises: a thermoelectric element that forms a heat absorption surface and a heat generation surface when power is supplied; a cold sink that contacts the heat absorption surface and has a guide channel formed inside; and a heat sink that contacts the heat generation surface and has a guide channel formed inside, wherein the refrigerant piping extending from the outlet of the expansion valve is connected to the inlet of the guide channel of the cold sink, and the inlet side piping of the evaporator connects the outlet of the guide channel of the cold sink and the inlet of the evaporator. Claim 2 delete Claim 3 delete Claim 4 A cooling cycle according to claim 1, characterized in that the outlet piping of the evaporator is connected to the inlet of the guide path of the heat sink, and the refrigerant piping extending from the outlet of the guide path of the heat sink is connected to the inlet of the compressor. Claim 5 In claim 4, the thermoelectric module further comprises an insulating material that surrounds the edge of the thermoelectric element to block heat transfer between the cold sink and the heat sink, and a case that accommodates the cold sink, the insulating material, the thermoelectric element, and the heat sink. Claim 6 A cooling cycle according to claim 5, further comprising a three-way valve mounted on the outlet-side piping of the condenser, wherein the expansion valve comprises a first expansion valve connected to one of two outlets provided in the three-way valve and a second expansion valve connected to the other of two outlets provided in the three-way valve, and the evaporator comprises a first evaporator connected to the outlet of the first expansion valve and a second evaporator connected to the outlet of the second expansion valve. Claim 7 In claim 6, the thermoelectric module comprises a first thermoelectric module connected to the inlet pipe and outlet pipe of the first evaporator, respectively, for heat exchange, and a second thermoelectric module connected to the inlet pipe and outlet pipe of the second evaporator, respectively, for heat exchange. Claim 8 A cooling cycle according to claim 6, wherein the evaporator comprises a first evaporator connected to the outlet-side piping of the expansion valve and a second evaporator connected to the outlet-side piping of the first evaporator, wherein the inlet-side piping connecting the expansion valve and the first evaporator is connected to the guide flow path inlet of the cold sink and the outlet-side piping of the second evaporator is connected to the guide flow path inlet of the heat sink. Claim 9 A cooling cycle according to claim 8, further comprising a bypass valve provided at a point in the inlet piping connecting the cold sink and the first evaporator, and a bypass piping extending from the bypass valve, wherein the bypass piping is joined at a point in the refrigerant piping connecting the first evaporator and the second evaporator.

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