Defrost controling system and method for heat pump

Abstract

The present invention relates to a defrosting control device and method for a heat pump, and more specifically, to a defrosting control device and method for a heat pump comprising: an ambient temperature sensor for measuring the temperature of external air flowing into an evaporator to control the start and end times of defrosting based on a frost rate derived from the evaporation pressure inside the evaporator and the low pressure of the refrigerant discharged from the evaporator; a low pressure sensor for measuring the low pressure of the refrigerant discharged from the evaporator; and a control unit electrically connected to the ambient temperature sensor and the low pressure sensor, and storing data indicating the relationship between the ambient temperature and the evaporation pressure and the relationship between the frost rate and the low pressure; wherein the control unit derives the evaporation pressure according to the ambient temperature measured by the ambient temperature sensor, derives the frost rate according to the low pressure measured by the low pressure sensor, and controls the start and end times of defrosting according to the derived frost rate.

Description

Technology Field

[0001] The present invention relates to a defrosting control device and method for a heat pump, and more specifically, provides a defrosting control device and method that controls the start and end times of defrosting based on a frost rate derived from the evaporation pressure inside the evaporator and the low pressure of the refrigerant discharged from the evaporator. Background Technology

[0002] A heat pump is a device that generally performs cooling and heating simultaneously, and its structure, as shown in FIG. 1, mainly includes a compressor (10), an air-refrigerant heat exchanger (20), an expansion valve (30), a brine-refrigerant heat exchanger (40), a four-way valve (50), and a refrigerant flow path (60). A known refrigerant for a refrigeration cycle is filled into the refrigerant flow path (60).

[0003] The compressor (10) is a component that compresses the refrigerant in a gaseous state to make it into a high-temperature, high-pressure gaseous state. Additional devices, such as an oil separator, may be installed at the outlet of the compressor (10). The air-refrigerant heat exchanger (20) is a type of heat exchanger and consists of a fin-and-tube heat exchanger (21) through which the refrigerant flows so that heat exchange occurs without mixing with the external air and refrigerant having a temperature difference, and a suction fan (22) that sucks in the external air. During cooling operation, it can function as a condenser in which the temperature and pressure of the refrigerant are lowered by heat exchange between the high-temperature, high-pressure refrigerant introduced from the compressor (10) and the external air.

[0004] The expansion valve (30) is a component that expands the refrigerant introduced from the air-refrigerant heat exchanger (20) into a low-temperature, low-pressure state, and changes the phase of the medium-temperature, high-pressure liquid state into a low-temperature, wet-saturated vapor state that is easy to evaporate. The brine-refrigerant heat exchanger (40) is a heat exchanger and is a component in which heat exchange occurs between brine and refrigerant with a temperature difference without mixing with each other. It may consist of a refrigerant coil (41) through which the refrigerant flows and a brine coil (42) through which the brine flows. The refrigerant supplied to the refrigerant coil (41) introduced from the expansion valve (30) receives heat from the brine and evaporates, thereby changing the phase of the refrigerant into a vapor state. The brine that has exchanged heat with the refrigerant is cooled and can be supplied to a heating and cooling unit through a brine circulation device (not shown). The four-way valve (50) installed at the outlet of the compressor (10) switches the direction of circulation of the refrigerant. For example, during cooling operation, the air-refrigerant heat exchanger (20) operates as a condenser and the brine-refrigerant heat exchanger (40) operates as an evaporator, and conversely, during heating operation, the flow of refrigerant is changed so that the air-refrigerant heat exchanger (20) operates as an evaporator and the brine-refrigerant heat exchanger (140) operates as a condenser.

[0005] When the heat pump operates as a heater, the high-temperature, high-pressure refrigerant compressed by the compressor (10) flows through the four-way valve (50) into the brine-refrigerant heat exchanger (40). The refrigerant flowing into the brine-refrigerant heat exchanger (40) is cooled by the brine flowing along the brine coil (42) and condensed into a liquid state. The refrigerant condensed in the brine-refrigerant heat exchanger (40) passes through the expansion valve (30), causing the pressure and temperature to drop rapidly, transforming into a two-phase refrigerant, which then flows into the air-refrigerant heat exchanger (20). The refrigerant flowing into the air-refrigerant heat exchanger (20) is rapidly cooled as it evaporates, and its temperature is lowered by heat exchange with the outside air introduced by the suction fan (22). That is, in the heating mode, the air-refrigerant heat exchanger (20) acts as an evaporator.

[0006] However, during the hot winter season, cold air flowing into the air-refrigerant heat exchanger (20) through the suction fan (22) causes a freezing phenomenon in which frost forms on the refrigerant tubes and cooling fins of the fin-and-tube heat exchanger (21). As time passes, the freezing area gradually increases and blocks the flow of air, resulting in poor heating. This formation of frost on the evaporator is called frost formation.

[0007] The ratio of the area of ​​the froze formed to the area of ​​the fin-and-tube heat exchanger (21) is called the frost formation rate. Therefore, if the frost formation rate is high, the flow of external air passing through the evaporator is blocked, making it impossible to change the refrigerant into a gaseous state, and as a result, the evaporation pressure of the refrigerant flowing inside the evaporator is lowered. Consequently, frost forms on the evaporator, and if the frost formation rate increases, the evaporator cannot perform its function, so a heat source must be applied to the evaporator to remove the frost formed on the surface, and this process is called defrosting.

[0008] Various defrosting methods have been proposed, including natural defrosting, which involves stopping the operation of a heat pump for a certain period; hot gas defrosting, which involves introducing hot gas to melt the material; electric defrosting, which involves installing an electric heater on the evaporator and supplying electricity at regular intervals; and spray defrosting, which removes the material by spraying water.

[0009] In addition, defrosting control methods that control the timing of when to start and when to end defrosting include using a timer to perform defrosting operations at regular intervals regardless of frost buildup, controlling the defrosting operation when the evaporator reaches a certain temperature, and determining the defrosting timing based on the difference between the evaporation temperature inside the evaporator and the temperature of the refrigerant discharged from the evaporator.

[0010] However, simply controlling defrosting based on the passage of a certain amount of time leads to the problem of excessive defrosting operation, while determining the timing based on the evaporator reaching a certain temperature results in inaccurate timing. In other words, accuracy is compromised by relying solely on temperature because frost formation depends not only on ambient temperature but also on humidity. For instance, frost may not occur if the ambient temperature is -4°C or lower, whereas severe frost formation may occur if the temperature is -4°C or higher, especially in the presence of snow or fog.

[0011] Furthermore, in methods that control defrosting based on the difference between the internal evaporation temperature and the temperature of the refrigerant discharged from the evaporator, an evaporation pressure sensor that converts pressure into temperature is used to measure the internal evaporation temperature; however, errors can occur during the process of converting pressure to temperature. Additionally, since the temperature of the refrigerant discharged from the evaporator is measured by detecting the surface temperature of the refrigerant pipes, there is a problem in accurately measuring the actual temperature. Moreover, because the difference between the evaporation temperature and the low-pressure temperature is not proportional to the frost formation rate, there are limitations to controlling defrosting based solely on the temperature difference. Prior art literature

[0012] Republic of Korea Patent Registration No. 10-0256317 (Publication Date: May 15, 2000) Republic of Korea Published Patent No. 10-2022-0067940 (Publication Date: May 25, 2022) The problem to be solved

[0013] The present invention aims to solve the problems of the prior art. The objective of the present invention is to provide a defrosting control device and method capable of precisely controlling defrosting and saving energy by controlling the start and end times of defrosting based on the frosting rate derived from the evaporation pressure inside the evaporator and the low pressure of the refrigerant discharged from the evaporator. means of solving the problem

[0014] As a means to achieve the purpose of the present invention,

[0015] The defrosting control device for a heat pump according to the present invention is,

[0016] A refrigeration cycle of a heat pump including a compressor, an evaporator, an expansion valve, a condenser, a four-way valve, and a refrigerant path;

[0017] An outside air temperature sensor that measures the temperature of the outside air flowing into the above evaporator;

[0018] A low-pressure pressure sensor for measuring the low-pressure pressure of the refrigerant discharged from the above evaporator;

[0019] It includes a control unit electrically connected to the above-mentioned ambient temperature sensor and low pressure sensor, and storing data indicating the relationship between ambient temperature and evaporation pressure and the relationship between frost rate and low pressure;

[0020] The above control unit is characterized by deriving an evaporation pressure based on the ambient temperature measured by the ambient temperature sensor, deriving a frost rate based on the evaporation pressure and the low pressure measured by the low pressure sensor, and controlling the start and end times of defrosting based on the derived frost rate.

[0021] In the present invention, the heat pump further includes a defrost water removal device for removing defrost water remaining in the fin-and-tube heat exchanger after defrosting operation.

[0022] The above-mentioned water removal device includes an air blast installed close to the fin-and-tube heat exchanger and strongly injecting air toward the fin-and-tube heat exchanger, and an air blast conveying device that horizontally conveys the air blast along the fin-and-tube heat exchanger.

[0023] The air blast described above includes a blower fan, a main body to which the blower fan is fixed and which forms an internal space, and a plurality of air nozzles formed on both sides of the main body and formed to spray air toward the fin-and-tube heat exchanger.

[0024] The air blast conveying device includes a guide rail installed parallel to the fin-and-tube heat exchanger and accommodating the lower end of the air blast to guide it in a horizontal direction, and a driving device that reciprocates the air blast along the guide rail.

[0025] As another embodiment of the present invention, a defrosting control method for a heat pump is,

[0026] In a defrosting control method using a defrosting control device of a heat pump according to the present invention,

[0027] A first step in which, after a certain period of time has passed since the heating operation, signals are received from the above-mentioned ambient temperature sensor and the above-mentioned low-pressure sensor to measure the ambient temperature flowing into the evaporator and the low-pressure pressure of the refrigerant discharged from the evaporator;

[0028] A second step of deriving evaporation pressure from the ambient temperature measured in the first step above;

[0029] A third step of deriving a frost rate from the low pressure measured in the first step and the evaporation pressure derived in the second step;

[0030] A fourth step of controlling the start and end times of defrosting based on the implantation rate derived in the third step above; wherein

[0031] The above control unit is characterized by deriving the evaporation pressure and the frost rate from stored data regarding ambient temperature and evaporation pressure, and data regarding the frost rate and low pressure.

[0032] After the end of the fourth stage of defrosting, it further includes a defrost water removal step of strongly injecting air toward the fin-and-tube heat exchanger of the evaporator to remove defrost water remaining in the fin-and-tube heat exchanger.

[0033] The above data regarding ambient temperature and evaporation pressure, and the data regarding frost rate and low pressure, are obtained through experiments; the above data regarding ambient temperature and evaporation pressure represent the measured evaporation pressure of a specific refrigerant according to changes in the set ambient temperature, and the above data regarding frost rate and low pressure represent the measured low pressure of a specific refrigerant according to changes in the set frost rate. Effects of the invention

[0034] According to the defrosting control device and method of the heat pump of the present invention, by controlling the start and end times of defrosting based on the frosting rate derived from the evaporation pressure inside the evaporator and the low pressure of the refrigerant discharged from the evaporator, defrosting can be controlled more precisely compared to conventional defrosting control devices and methods based on temperature or temperature difference, and the effect of preventing excessive defrosting operation, thereby saving energy and maintaining stable heating efficiency is achieved. Brief explanation of the drawing

[0035] FIG. 1 is a schematic diagram showing an example of a refrigeration cycle equipped with a defrosting control device according to the present invention. Figure 2 is a schematic graph showing the relationship between ambient temperature, evaporation pressure, low pressure, and frost rate. FIG. 3 is a flowchart showing a defrosting control method according to the present invention, FIG. 4 is a perspective view showing a preferred embodiment of a water removal device according to the present invention, FIG. 5 is a perspective view showing an example of an air-refrigerant heat exchanger equipped with a defrosting water removal device of the present invention. Specific details for implementing the invention

[0036] The advantages and features of the embodiments disclosed in this specification, and the methods for achieving them, will become clear by referring to the embodiments described below in conjunction with the accompanying drawings. However, the embodiments proposed in this invention are not limited to the embodiments disclosed below and can be implemented in various different forms; these embodiments are provided merely to fully inform those skilled in the art of the scope of the embodiments.

[0037] The terms used in this specification have been selected to be as widely used as possible, taking into account the functions of the disclosed embodiments; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms have been arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the relevant detailed description section of the specification. Therefore, terms used in this disclosure should be defined not merely by their names, but based on their meanings and the content throughout this specification.

[0038] In this specification, singular expressions include plural expressions unless the context clearly indicates that they are singular. Furthermore, when a part throughout the specification is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Additionally, in the description with reference to the accompanying drawings, identical components are assigned the same reference numeral regardless of the drawing number, and redundant descriptions thereof are omitted. In describing the present invention, if it is determined that a detailed description of related prior art could unnecessarily obscure the essence of the invention, such detailed description is omitted.

[0039] First, FIG. 1 is a schematic diagram showing a preferred embodiment of a refrigeration cycle of a heat pump according to the present invention.

[0040] As described above, an outside air temperature sensor (71) is installed around an air-refrigerant heat exchanger (20) (hereinafter referred to as the 'evaporator') to measure the temperature of the outside air flowing into the evaporator, and a low-pressure sensor (72) is installed in the refrigerant flow path (60) between the evaporator (20) and the compressor (10) to directly measure the pressure of the refrigerant discharged from the evaporator.

[0041] The control unit (80) includes a memory that stores experimental values ​​of evaporation pressure according to changes in ambient temperature and experimental values ​​of low pressure according to changes in frost rate, and a calculation unit that derives evaporation pressure according to the ambient temperature measured by the ambient temperature sensor (71), derives frost rate according to the low pressure measured by the low pressure sensor (72), and controls the start and end times of defrosting according to the derived frost rate.

[0042] Figure 2 is a schematic graph illustrating the relationship between ambient temperature and evaporation pressure, and between low pressure and frost formation rate.

[0043] The refrigerant entering the evaporator absorbs heat from the outside air and undergoes a phase change into a vapor state as it evaporates. In order to extract heat from the cold air in the evaporator, the evaporation temperature of the refrigerant must be lower than the ambient temperature. Furthermore, the lower the evaporation temperature, the lower the evaporation pressure of the refrigerant. Therefore, there is a proportional relationship between the ambient temperature and the evaporation pressure.

[0044] When no frost forms on the evaporator, all the refrigerant entering the evaporator evaporates and becomes a gas. At this time, the evaporation pressure of the refrigerant—that is, the evaporation pressure in the saturated state—has a unique value for the refrigerant. Therefore, the evaporation pressure according to the ambient temperature must be obtained from the refrigerant manufacturer or determined directly through experiments.

[0045] Conversely, if frost forms on the evaporator, heat exchange between the refrigerant and the outside air is not efficient. Since the refrigerant does not evaporate completely, the refrigerant remains in a mixed state of gas and liquid, causing the internal pressure of the evaporator to drop below the saturation evaporation pressure. In other words, the low-pressure of the refrigerant discharged from the evaporator becomes relatively lower than the saturation evaporation pressure. Therefore, if the low-pressure drops below the evaporation pressure, it can be considered that frost has formed on the evaporator.

[0046] Furthermore, when frost forms on the evaporator, the low-pressure pressure becomes lower than the evaporation pressure, resulting in a difference between the two. Additionally, as the difference between the evaporation pressure and the low-pressure pressure increases, the frost formation rate also increases. However, since there is no direct correlation between the difference between the evaporation pressure and the low-pressure pressure and the frost formation rate, there are limitations to deriving the rate based solely on this difference. Therefore, to determine the frost formation rate, the relationship between the frost formation rate and the low-pressure pressure must be established in advance through experiments.

[0047] For example, the ambient temperature can be measured using an ambient temperature sensor (71) installed around the evaporator (20), and the low-pressure temperature can be measured using a low-pressure pressure sensor (72) installed in the refrigerant pipe between the evaporator (20) and the compressor (10).

[0048] Furthermore, evaporation pressure is proportional to the evaporation temperature. In other words, for heat exchange to occur between the refrigerant and the outside air in the evaporator, the evaporation temperature must be lowered by a certain amount (e.g., 15°C) compared to the ambient temperature. Additionally, evaporation pressure is proportional to the evaporation temperature. Therefore, if the ambient temperature is known, the evaporation temperature and evaporation pressure can be derived.

[0049] Ambient temperature (°C) Evaporation temperature (°C) Evaporation pressure (mb) Low pressure (mb) 70% implantation rate Implantation rate 30% 0 -15 1.98 1.02 1.19 -1 -16 1.87 0.93 1.1 -2 -17 1.76 0.85 1.02 -3 -18 1.66 0.78 0.93 -4 -19 1.56 0.7 0.85 -5 -20 1.46 0.63 O.78

[0050] As shown in Table 1, by measuring the evaporation pressure while varying the ambient temperature in 1°C increments, the evaporation temperature and evaporation pressure can be derived from the ambient temperature. For example, when the ambient temperature is 0°C, the evaporation temperature is -15°C and the evaporation pressure is 1.98. That is, when the ambient temperature is 0°C in a saturated state where no frost forms in the evaporator, the evaporation pressure is derived as 1.98.

[0051] However, if frost forms on the evaporator, the refrigerant does not evaporate sufficiently, so the low-pressure discharged from the evaporator becomes lower than the evaporation pressure in the saturated state. The low-pressure can be varied to 10%, 30%, 50%, and 70% by adjusting the amount of air passing through the evaporator. As shown in Table 1, when the frost rate is set to 70% at an ambient temperature of 0°C, the total pressure is measured as 1.02, and when the frost rate is adjusted to 30%, the low-pressure is measured as 1.19. In other words, it can be confirmed that the low-pressure changes according to the change in the frost rate.

[0052] Therefore, by measuring the low pressure of the refrigerant discharged from the evaporator, the frost rate can be derived in reverse. For example, as shown in Table 1, when the ambient temperature is 0°C, if the low pressure is 1.02, the frost rate is derived to be 70%, and if the low pressure is 1.19, the frost rate is derived to be 30%.

[0053] In this way, the relationship between ambient temperature and evaporation pressure, and the relationship between the frost rate and low pressure, can be predetermined. Based on the measured ambient temperature, the evaporation pressure can be derived, and based on the measured low pressure, the frost rate can be derived. Furthermore, based on the derived frost rate, the start and end times of defrosting can be controlled.

[0054] That is, the defrosting control device (70) of the present invention is characterized by including an outside air temperature sensor (71) for measuring the temperature of outside air flowing into the air-refrigerant heat exchanger (20), a low pressure sensor (72) for measuring the low pressure of the refrigerant discharged from the air-refrigerant heat exchanger (20), and a control unit that stores data indicating the relationship between the outside air temperature and the evaporation pressure and the relationship between the frost rate and the low pressure, derives the evaporation pressure according to the outside air temperature measured by the outside air temperature sensor (71), derives the frost rate using the low pressure and evaporation pressure measured by the low pressure sensor (72), and controls the start and end times of defrosting according to the derived frost rate.

[0055] FIG. 3 is a flowchart showing the defrosting control method of the present invention. As shown, when the heating operation has been running for a certain period of time, the control unit (80) periodically receives signals from the outside air temperature sensor (71) and the low pressure sensor (72) and measures the outside air temperature flowing into the evaporator (20) and the low pressure of the refrigerant discharged from the evaporator (20) (Step 1).

[0056] Next, the control unit (80) derives the evaporation pressure from the measured ambient temperature. That is, the control unit (80) can derive the evaporation pressure corresponding to the ambient temperature from the data regarding the ambient temperature and evaporation pressure stored in memory (step 2).

[0057] Additionally, the control unit (80) derives the frost rate from the measured low pressure. That is, the control unit (80) can derive the frost rate corresponding to the low pressure and evaporation pressure from the data regarding the low pressure and frost rate stored in memory (Step 3).

[0058] For example, when the ambient temperature measured in Table 1 is -5℃, the evaporation pressure is derived as 1.46, and when the low pressure is measured as 0.63 while the evaporation pressure is 1.46, the frost rate can be derived as 70% using the evaporation pressure of 1.46 and the low pressure of 0.63, and the frost rate can be derived as 30% using the evaporation pressure of 1.46 and the low pressure of 0.78. In this case, the frost rate is 70%, and when the measured low pressure is 0.78, the frost rate is derived as 30%.

[0059] Next, the control unit (80) can command the start of defrosting operation if the derived frost rate is above a certain level (e.g., 50%) and command the end of defrosting operation if the frost rate drops below a certain level (e.g., 10%) (step 4).

[0060] Additionally, the control unit (80) can remove the defrosting water remaining in the evaporator (20) for a certain period of time after the defrosting operation is finished (step 5).

[0061] That is, after defrosting is performed, defrost water may remain in the fin-and-tube heat exchanger. In particular, if the fin-and-tube heat exchanger (21) is installed at an angle, defrost water remains between the cooling fins that are brazed perpendicular to the refrigerant tubes. If the heating mode is restarted in this state, the defrost water freezes, causing a decrease in heating performance.

[0062] The present invention provides a defrost water removal device for removing defrost water remaining in a fin-and-tube heat exchanger after defrosting operation, thereby preventing the remaining defrost water from freezing and reducing heating performance.

[0063] FIG. 4 is a perspective view showing a water removal device according to the present invention, and FIG. 5 is a perspective view showing an example of an evaporator in which the water removal device of the present invention is installed.

[0064] As described, the water removal device (60) includes an air blast (61) installed close to the fin-and-tube heat exchanger (21) and strongly blowing air toward the fin-and-tube heat exchanger, and an air blast conveying device (65) that horizontally conveys the air blast (61) along the fin-and-tube heat exchanger (21).

[0065] The air blast (61) is for strongly blowing air toward the fan-and-tube heat exchanger (21) and comprises a blower fan (613), a main body (611) that supports the blower fan (613) and forms an internal space, and a plurality of air nozzles (615) formed on both sides of the main body (611) and configured to blow air toward the fan-and-tube heat exchanger (21).

[0066] Preferably, the main body (611) is formed as a flat box of a triangular shape that forms a space of a certain size inside, and its width narrows toward the bottom. On both sides, inclined surfaces are formed at the same angle as the fin-and-tube heat exchanger (21), and a plurality of air nozzles (615) are formed along these inclined surfaces. Additionally, a blower fan (613) for blowing air into the interior of the main body (611) is installed on the upper surface of the main body (611).

[0067] Therefore, after the defrosting operation, when the blower fan (613) is operated, the air blown by the blower fan (613) is sprayed toward the fin-and-tube heat exchanger (21) through a plurality of air nozzles (615) to blow out the defrosting water remaining between the cooling fins (121b). At this time, a plurality of air nozzles (615) are installed so as to cover the height of the fin-and-tube heat exchanger (21).

[0068] The air blast conveyor (65) is for conveying the air blast (61) in a horizontal direction. During heating operation, it is positioned at one edge of the fin-and-tube heat exchanger (21) to allow external air to pass through the heat exchanger smoothly, and during defrosting water removal, it moves back and forth along the fin-and-tube heat exchanger (21) to remove all defrosting water remaining in the heat exchanger.

[0069] To this end, the air blast conveyor (65) includes a guide rail (656) installed parallel to the fin-and-tube heat exchanger (21) and accommodating the lower end of the air blast (61) to guide it in a horizontal direction, and a drive device that drives the air blast (61) to move back and forth along the guide rail (656).

[0070] Preferably, the driving device includes a ball nut (652) fixed to the bottom of the air blast (61), a screw shaft (654) that is fastened to and penetrates the ball nut (652) and is installed longitudinally in the center of the guide rail (656), and a geared motor (658) connected to one end of the screw shaft (654) to rotate it. At this time, a support wing may be integrally formed at the bottom of the blast body (610) to support the air blast (61) so that it does not rotate around the screw shaft (654). In addition, as shown in FIG. 5, two limit switches (659) that limit the travel distance of the air blast (61) are installed on the inner surface of the housing (101).

[0071] Accordingly, when the geared motor (658) operates and the screw shaft (654) rotates, the ball nut (652) attached to the screw shaft (654) moves horizontally along the screw shaft (654), and the air blast (61) moves horizontally together with the ball nut (652). Then, when the air blast (61) comes into contact with the limit switch (659), the rotation direction of the geared motor (658) changes or stops. In this way, the air blast (610) moves back and forth horizontally and strongly sprays air, thereby removing the defrosting water remaining on the cooling fins (121b) of the fin-and-tube heat exchanger (21).

[0072] As such, the defrosting control device and method according to the present invention controls the start and end times of defrosting based on the frosting rate derived from the evaporation pressure inside the evaporator and the low pressure of the refrigerant discharged from the evaporator, thereby enabling more precise control of defrosting compared to conventional defrosting control devices and methods based on temperature or temperature difference, and preventing excessive defrosting operation, which has the effect of saving energy and maintaining stable heating efficiency.

[0073] Although the present invention has been described above using several preferred embodiments, these embodiments are illustrative and not limiting. Those skilled in the art will understand that various changes and modifications can be made without departing from the spirit of the invention and the scope of the rights set forth in the appended claims. Explanation of the symbols

[0074] 20: Air-refrigerant heat exchanger (evaporator) 40: Brine-refrigerant heat exchanger (condenser) 71: Outdoor temperature sensor 72: Low pressure sensor 60: Water removal device 61: Air blast 65: Air blast conveyor 71: Ambient temperature sensor 72: Low pressure sensor

Claims

Claim 1 delete Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 A refrigeration cycle of a heat pump comprising a compressor, an evaporator consisting of one or more fin-and-tube heat exchangers, an expansion valve, a condenser, a four-way valve, and a refrigerant path; An ambient temperature sensor for measuring the temperature of external air flowing into the evaporator; a low-pressure pressure sensor for measuring the low-pressure pressure of a refrigerant discharged from the evaporator; a control unit electrically connected to the ambient temperature sensor and the low-pressure pressure sensor, storing data indicating the relationship between the ambient temperature and the evaporation pressure and the relationship between the frost rate and the low-pressure pressure, deriving the evaporation pressure according to the ambient temperature measured by the ambient temperature sensor, deriving the frost rate according to the low-pressure pressure measured by the low-pressure pressure sensor, and controlling the start and end times of defrosting according to the derived frost rate; and a defrost water removal device electrically connected to the control unit and removing defrost water remaining in the fin-and-tube heat exchanger after defrosting operation; wherein the defrost water removal device comprises an air blast installed close to the fin-and-tube heat exchanger and strongly injecting air toward the fin-and-tube heat exchanger, and an air blast conveying device for horizontally conveying the air blast along the fin-and-tube heat exchanger; and wherein the air blast The apparatus comprises a blower fan, a main body to which the blower fan is fixed and which forms an internal space, and a plurality of air nozzles formed on both sides of the main body and configured to blow air toward the fin and tube heat exchanger, wherein the main body is made of a flat box of a triangular shape that forms a space of a certain size inside, and its width narrows toward the bottom, and inclined surfaces are formed on both sides at the same angle as the fin and tube heat exchanger, and the plurality of air nozzles are formed along these inclined surfaces, and the blower fan is installed to blow air into the interior from the upper surface of the main body;The above air blast transfer device comprises a guide rail installed parallel to the fin-and-tube heat exchanger and accommodating the lower end of the air blast to guide it in a horizontal direction, and a driving device that reciprocates the air blast along the guide rail, wherein during heating operation, it is positioned at one edge of the fin-and-tube heat exchanger to allow external air to pass smoothly through the heat exchanger, and during defrost water removal, it reciprocates along the fin-and-tube heat exchanger to remove all defrost water remaining in the heat exchanger; and the control unit comprises: a first step of receiving signals from the ambient temperature sensor and the low pressure sensor after a certain period of time has elapsed during heating operation to measure the ambient temperature flowing into the evaporator and the low pressure of the refrigerant discharged from the evaporator; a second step of deriving the evaporation pressure from the ambient temperature measured in the first step; a third step of deriving the frost rate from the low pressure measured in the first step and the evaporation pressure derived in the second step; and a fourth step of controlling the start and end times of defrosting based on the frost rate derived in the third step; wherein the Data regarding ambient temperature and evaporation pressure are obtained through preliminary experiments on a specific refrigerant, wherein the evaporation pressure represents the measured evaporation pressure of a specific refrigerant according to a change in ambient temperature measured by the ambient temperature sensor, and data regarding the frost rate and low pressure represent the measured low pressure of a specific refrigerant according to a change in the set frost rate; and the control unit, after the defrosting operation, operates the blower fan and the drive device to blow air blown from the blower fan toward the fin-and-tube heat exchanger through a plurality of air nozzles while simultaneously transporting it horizontally along the fin-and-tube heat exchanger, thereby blowing out the defrosting water remaining between the cooling fins, characterized in that the defrosting control method of a heat pump is characterized by the above. Claim 7 delete

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