JP5183618B2 - Heat pump equipment - Google Patents

Description

  The present invention relates to a heat pump device, and particularly relates to defrosting start determination control for accurately detecting a frosting state in an evaporator and starting a defrosting operation at an appropriate timing.

2. Description of the Related Art Conventionally, there are air conditioners that perform defrosting operation start determination by determining icing of an outdoor heat exchanger using an indoor heat exchanger piping temperature sensor and an indoor intake temperature sensor during heating operation (see, for example, Patent Document 1). .
The heat pump water heater includes an evaporator for exchanging heat between the atmosphere and the refrigerant, an outside air temperature detecting means for detecting the outside air temperature, and an evaporator temperature detecting means for detecting the evaporator temperature, and is attached to the evaporator. When performing the defrosting operation to remove frost, the first conditional expression and the second conditional expression have the first conditional expression and the second conditional expression obtained from the correlation between the outside air temperature and the evaporator temperature. When the start of the defrosting operation is determined based on the area formed by the first defrosting operation and the second and subsequent defrosting operations are performed, the correction coefficient is applied to the first conditional expression and the second conditional expression according to the previous defrosting operation time. In addition, there is one that corrects the first conditional expression and the second conditional expression to correct the determination region of the start of the defrosting operation (see, for example, Patent Document 2).

JP-A-9-210516 (page 3-4, FIG. 3) JP 2008-51361 A (Page 6, FIG. 2-3)

  Usually, in an evaporator of a heat pump device, when the evaporation temperature is 0 ° C. or less and the dew point temperature of air or less, a frosting phenomenon in which frost grows on the evaporator surface occurs. When this frosting phenomenon occurs, the ventilation resistance in the evaporator is increased, the performance of the heat exchanger is lowered, and the operation efficiency of the heat pump device is lowered, so defrosting operation to remove frost grown on the evaporator surface is necessary. It becomes.

  Currently, in air conditioners and heat pump water heaters, etc., those that determine the frosting condition on the evaporator from the difference between the evaporator intake air temperature and the evaporator refrigerant temperature, the condenser refrigerant temperature and the condenser intake air temperature There is one that determines the frost formation state on the evaporator from the difference between the two. However, since the evaporator refrigerant temperature and the condenser refrigerant temperature change not only due to frost but also due to changes in compressor frequency or load fluctuations, it is erroneously determined that frost is formed even when frost is not formed. There is a problem that it is erroneously determined that frost is formed but not frosted.

  The present invention has been made to solve the above-described problems, and provides a heat pump device that can accurately determine the start of a defrosting operation without being affected by changes in compressor frequency, load fluctuations, and the like. For the purpose.

The heat pump device according to the present invention detects a refrigerant circuit in which a compressor, a condenser, an expansion device, and an evaporator are annularly connected by a refrigerant pipe, and a saturation temperature (hereinafter referred to as “evaporation temperature”) of the refrigerant in the evaporator. An evaporator temperature detecting means for detecting the temperature of the air sent to the evaporator (hereinafter referred to as “evaporator intake air temperature”), and a flow rate of the refrigerant flowing through the refrigerant circuit. A refrigerant flow rate detecting means for detecting, and a control unit for performing a defrosting operation start determination as to whether or not to start the defrosting operation, wherein the control unit detects the evaporation detected by the evaporator temperature detecting means. Based on the temperature, the evaporator suction air temperature detected by the evaporator suction air temperature detecting means, and the refrigerant flow rate detected by the refrigerant flow rate detecting means, the amount of air passing through the evaporator The amount of air is calculated, and the pressure loss is derived from the air volume based on a predetermined relationship between the pressure loss of the air passing through the evaporator and the air volume. And calculating the wind speed of the air passing through the evaporator from the pressure loss at the time of non-frost formation derived from the air volume based on the predetermined relationship, and based on the calculated air volume and the wind speed, the evaporation The thickness of frost generated in the vessel (hereinafter referred to as “frost layer thickness”) is calculated, and when the frost layer thickness is equal to or greater than a predetermined threshold, the defrosting operation is performed , and the frost layer When the thickness is t_frost, the air volume is Va, the wind speed is U, the evaporator height is H, the width is W, the fin plate thickness is tf, and the fin pitch is fp, the air volume Va and the wind speed U are based on, to calculate the frost layer thickness t_frost by the following formula And features.
t_frost = (U × H × W × fp−U × H × W × ft−Va × fp) / (2 × U × H × W)

  According to the present invention, the frost layer thickness is calculated for the frost adhering to the evaporator, and the start determination of the defrosting operation is performed based on the frost layer thickness. Even when the operating state of the heat pump device changes due to the above, erroneous determination can be prevented in the start determination of the defrosting operation.

It is a schematic block diagram of the refrigerant circuit of the heat pump apparatus which concerns on Embodiment 1 of this invention. It is a block diagram of the control system in the heat pump apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the defrost driving | operation operation | movement of the heat pump apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the start determination operation | movement of the defrost driving | operation of the heat pump apparatus which concerns on Embodiment 1 of this invention. It is a graph which shows the relationship between the opening degree of the expansion valve 4 of the heat pump apparatus which concerns on Embodiment 1 of this invention, and its Cv value. It is a figure which shows the relationship between the air volume of the air which passes the evaporator 5 of the heat pump apparatus which concerns on Embodiment 1 of this invention, and the pressure loss in that case. It is a block diagram of the evaporator 5 of the heat pump apparatus which concerns on Embodiment 1 of this invention. It is a block diagram of the control system in the heat pump apparatus which concerns on Embodiment 2 of this invention. It is a flowchart which shows the start determination operation | movement of the defrost operation of the heat pump apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the relationship between the normal operation time of the heat pump apparatus which concerns on Embodiment 2 of this invention, and the frost layer thickness in the evaporator 5. FIG. It is a block diagram of the evaporator 5 of the heat pump apparatus which concerns on Embodiment 3 of this invention. It is a block diagram of the evaporator 5 and the fan 7 for evaporators of the heat pump apparatus which concerns on Embodiment 4 of this invention. It is a schematic block diagram of the refrigerant circuit of the heat pump apparatus which concerns on Embodiment 5 of this invention. It is a schematic block diagram of the refrigerant circuit of the heat pump apparatus which concerns on Embodiment 6 of this invention.

Embodiment 1 FIG.
(Configuration of heat pump device)
FIG. 1 is a schematic configuration diagram of a refrigerant circuit of a heat pump device according to Embodiment 1 of the present invention, and FIG. 2 is a block diagram of a control system in the heat pump device.
The heat pump device according to the present embodiment includes at least a compressor 1, a four-way valve 2, a condenser 3, an expansion valve 4, and an evaporator 5, and the compressor 1, the four-way valve 2, the condenser 3, and an expansion valve. 4, the evaporator 5, the four-way valve 2, and the compressor 1 are connected in this order by refrigerant piping to constitute a refrigerant circuit. Moreover, the heat pump apparatus according to the present embodiment includes a control unit 100 that controls the operations of the compressor 1 and the four-way valve 2 described above, as shown in FIG.

  The four-way valve 2 has a function of switching the flow path of the gas refrigerant discharged from the compressor 1. In the normal operation, the four-way valve 2 has a flow path through which the gas refrigerant discharged from the compressor 1 flows into the condenser 3 and the refrigerant that flows out of the evaporator 5 flows into the compressor 1. Configure. In the case of a defrosting operation that removes frost generated in the evaporator 5, the four-way valve 2 is configured so that the gas refrigerant discharged from the compressor 1 flows into the evaporator 5 and flows out from the condenser 3. Constitutes a flow path that flows into the compressor 1.

  The condenser 3 is provided with a condenser fan 6 in the vicinity thereof. In the normal operation, the condenser 3 is sent by the rotation of the condenser fan 6 and the gas refrigerant discharged from the compressor 1 and passing through the four-way valve 2. Heat exchange with air is performed to condense the gas refrigerant. Further, the condenser fan 6 is connected to a condenser fan motor 6a that is driven to rotate. A condenser refrigerant pressure detection means 10 is installed in the refrigerant pipe on the inflow side of the condenser 3.

  The expansion valve 4 expands and decompresses the liquid refrigerant that has flowed in, and flows it out as a low-temperature and low-pressure gas-liquid two-phase refrigerant. The expansion valve 4 is provided with expansion valve opening degree detection means 11 for detecting the opening degree. An expansion valve inlet refrigerant temperature detection means 12 is installed in the refrigerant pipe on the inflow side of the expansion valve 4.

  The evaporator 5 includes an evaporator fan 7 in the vicinity thereof, and in normal operation, heat exchange is performed between the refrigerant flowing out of the expansion valve 4 and the air sent by the rotation of the evaporator fan 7. Then, the refrigerant is vaporized. The evaporator fan 7 is connected to an evaporator fan motor 7a that is driven to rotate. Further, the evaporator 5 is provided with an evaporator suction air temperature detecting means 8 for detecting the temperature of the air sent by the rotational drive of the evaporator fan. An evaporator refrigerant pressure detection means 9 is installed in the refrigerant pipe on the outflow side of the evaporator 5.

  As shown in FIG. 2, the controller 100 includes an evaporator intake air temperature detection means 8, an evaporator refrigerant pressure detection means 9, a condenser refrigerant pressure detection means 10, an expansion valve opening degree detection means 11, and an expansion valve inlet. Refrigerant temperature detection means 12 are connected to each other, and temperature information, pressure information and opening degree information (hereinafter referred to as “detection information”) output from each detection means are transmitted to the control unit 100. In addition, the control unit 100 includes a memory 101 and a calculation unit 102. The control unit 100 is connected to the compressor 1, the four-way valve 2, the condenser fan motor 6a, the evaporator fan motor 7a, and the expansion valve 4, and controls their operations.

  The memory 101 stores detection information received from the detection means by the control unit 100. The calculation unit 102 calculates based on the detection information from each of the detection means stored in the memory 101, and the control unit 100 controls the operation of each actuator based on the calculation result.

  The expansion valve 4 corresponds to the “expansion device” of the present invention, the expansion valve opening degree detection means 11 corresponds to the “expansion device opening degree detection means” of the present invention, and the expansion valve inlet refrigerant temperature detection means 12 Corresponds to “expansion device inlet refrigerant temperature detection means” of the present invention.

(Normal operation of heat pump device)
Next, the normal operation of the heat pump device according to the present embodiment will be described with reference to FIG.
The high-temperature and high-pressure gas refrigerant compressed and discharged by the compressor 1 flows into the condenser 3 via the four-way valve 2. The gas refrigerant that has flowed into the condenser 3 undergoes heat exchange with the air sent by the rotational drive of the condenser fan 6, condenses, becomes liquid refrigerant, and flows out of the condenser 3. At this time, the condenser 3 radiates heat by condensation of the gas refrigerant. The liquid refrigerant flowing out of the condenser 3 flows into the expansion valve 4 and is expanded and depressurized by the expansion valve 4 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant. This gas-liquid two-phase refrigerant flows into the evaporator 5, undergoes heat exchange with the air sent by the rotational drive of the evaporator fan 7, vaporizes, and becomes a low-temperature and low-pressure gas refrigerant from the evaporator 5. leak. The gas refrigerant flowing out of the evaporator 5 flows into the compressor 1 through the four-way valve 2 and is compressed again.

(Defrosting operation of heat pump device)
When the heat pump device according to the present embodiment is normally operated, in the evaporator 5, when the refrigerant temperature is 0 ° C. or lower and the air outdoor temperature or lower, moisture contained in the air is evaporated to the evaporator 5. A frosting phenomenon occurs that grows into frost by adhering to the surface. Due to the frosting phenomenon in the evaporator 5, the air flow path in the evaporator 5 is blocked, the ventilation resistance is increased, and the air volume is reduced, so that the heat exchange amount is reduced and the heat exchange capacity can be sufficiently exhibited. Disappear. Therefore, in the evaporator 5, when frosting progresses to some extent, a defrosting operation for removing frost is required.

  FIG. 3 is a diagram showing a defrosting operation operation of the heat pump device according to Embodiment 1 of the present invention. As shown in FIG. 3, the normal defrosting operation is generally performed by switching the four-way valve 2 by the control unit 100 and causing the refrigerant to flow in the opposite direction to that in the normal operation. Hereinafter, the defrosting operation of the heat pump device according to the present embodiment will be described with reference to FIG.

  The high-temperature and high-pressure gas refrigerant compressed and discharged by the compressor 1 flows into the evaporator 5 via the four-way valve 2. The gas refrigerant that has flowed into the evaporator 5 undergoes heat exchange with the air sent by the rotational drive of the evaporator fan 7, condenses, becomes liquid refrigerant, and flows out of the evaporator 5. At this time, the frost adhering to the evaporator 5 is dissolved by the heat released by the condensation of the gas refrigerant. The liquid refrigerant flowing out of the evaporator 5 flows into the expansion valve 4 and is expanded and decompressed by the expansion valve 4 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant. This gas-liquid two-phase refrigerant flows into the condenser 3, undergoes heat exchange with the air sent by the rotational drive of the condenser fan 6, vaporizes, and becomes a low-temperature and low-pressure gas refrigerant from the condenser 3. leak. The gas refrigerant flowing out of the condenser 3 flows into the compressor 1 through the four-way valve 2 and is compressed again.

(Start determination operation of defrosting operation of heat pump device)
FIG. 4 is a flowchart showing the start determination operation of the defrosting operation of the heat pump device according to Embodiment 1 of the present invention, and FIG. 5 shows the relationship between the opening degree of the expansion valve 4 of the heat pump device and its Cv value. 6 is a graph showing the relationship between the air volume passing through the evaporator 5 of the heat pump device and the pressure loss at that time, and FIG. 7 is the evaporator of the heat pump device. FIG. Hereinafter, the start determination operation of the defrosting operation of the heat pump device according to the present embodiment will be described with reference to FIGS. 4 to 7.

(S1)
First, the control unit 100 starts normal operation.

(S2)
When the normal operation is started, the control unit 100 determines that the evaporator suction air temperature Ta detected by the evaporator suction air temperature detection means 8, the evaporation pressure Pe detected by the evaporator refrigerant pressure detection means 9, and the condenser refrigerant. The condensation pressure Pc detected by the pressure detection means 10, the expansion valve opening P detected by the expansion valve opening detection means 11, and the expansion valve inlet temperature Tsc detected by the expansion valve inlet refrigerant temperature detection means 12 are received. . Based on the evaporation pressure Pe, the condensation pressure Pc, the expansion valve opening degree P, and the expansion valve inlet temperature Tsc, the calculation unit 102 of the control unit 100 calculates the refrigerant flow rate Gr at the time of non-frosting according to the following equation (1). calculate. And the calculating part 102 calculates evaporation temperature Te which is the saturation temperature of a refrigerant | coolant based on said evaporation pressure Pe.

  Gr = 86.5 × Cv × √ ((Pc−Pe) / ρ) (1)

  Here, Cv in equation (1) is the Cv value of the expansion valve 4 and is unique to the expansion valve 4, and has the relationship as shown in FIG. Is a value easily determined from the expansion valve opening P. Further, the density ρ in the equation (1) indicates the density of the liquid refrigerant at the inlet of the expansion valve 4 and is calculated based on the condensation pressure Pc and the expansion valve inlet temperature Tsc.

  The expansion valve opening P corresponds to the “expansion device opening” of the present invention, and the expansion valve inlet temperature Tsc corresponds to the “expansion device inlet temperature” of the present invention.

(S3)
In step S2, the calculation unit 102 sets the evaporator suction air temperature Ta detected by the evaporator suction air temperature detection means 8 as Ta_i, the calculated evaporation temperature Te as Te_i, and the calculated refrigerant flow rate Gr as Gr_i. To remember.

(S4)
In step S3, after the evaporator suction air temperature Ta_i, the evaporation temperature Te_i, and the refrigerant flow rate Gr_i at the start of normal operation are stored in the memory 101, the control unit 100 reads the current evaporator suction air temperature Ta, the evaporation pressure. Pe, condensing pressure Pc, expansion valve opening P, and expansion valve inlet temperature Tsc are received from each detecting means. The computing unit 102 calculates the current refrigerant flow rate Gr by Equation (1) based on the evaporation pressure Pe, the condensation pressure Pc, the expansion valve opening P, and the expansion valve inlet temperature Tsc. And the calculating part 102 calculates evaporation temperature Te based on said evaporation pressure Pe.

(S5)
The relationship that the heat exchange amount Q in the evaporator 5 is proportional to the refrigerant flow rate Gr, and the heat exchange amount Q is the difference between the evaporator intake air temperature Ta and the evaporation temperature Te, and the amount of air flowing through the evaporator 5. From the relationship of being proportional to the product of Va, the refrigerant flow rate Gr is derived from the difference between the evaporator intake air temperature Ta and the evaporation temperature Te, and the relationship expressed by the following equation (2) with the air volume Va.

  Gr∝Va × (Ta-Te) (2)

  The calculation unit 102 calculates the evaporator intake air temperature Ta_i, the evaporation temperature Te_i, the refrigerant flow rate Gr_i, the known air flow Va_i during non-frosting, and the evaporator detected in step S4, which are stored in the memory 101 in step S3. Based on the intake air temperature Ta and the evaporation temperature Te calculated in step S4, the current air volume Va is calculated by the following equation (3) derived from the above equation (2).

  Va = Gr / Gr_i * Va_i * (Ta_i-Te_i) / (Ta-Te) (3)

  Further, the air volume Va and the pressure loss ΔP have a relationship as shown in FIG. 6, and the pressure loss ΔP is easily determined based on the air volume Va. Furthermore, since the pressure loss ΔP is proportional to the square of the wind speed U of the air passing through the evaporator 5, the relationship shown in the following (4) is derived.

  ΔP∝U ^ 2 (4)

  Here, “^” is an operator indicating a power. ΔP_i is the pressure loss at the start of normal operation, U_i is the speed of the air passing through the evaporator 5, and ΔP is the current pressure loss determined from the relationship of FIG. 6 based on the air volume Va calculated by the above equation (3). And if the wind speed of the air which passes the present evaporator 5 is set to U, the following formula | equation (5) will be guide | induced from the relationship of Formula (4).

  ΔP_i / ΔP = (U_i ^ 2) / (U ^ 2) (5)

  In addition, in the evaporator 5 having the height H, the width W, the fin plate thickness tf, and the fin pitch fp as shown in FIG. 7, if the passage area through which air passes during non-frosting is S_i, the passage area S_i is: It is calculated by the following equation (6).

  S_i = W × H−tf × H × W / fp (6)

  Moreover, the wind speed U_i of the air which passes the evaporator 5 at the time of this non-frosting is calculated by the following formula | equation (7).

  U_i = Va_i / S_i (7)

  The calculation unit 102 determines the pressure loss ΔP_i determined from the relationship of FIG. 6 based on the known air flow Va_i during non-frosting, and the current pressure loss ΔP determined from the relationship of FIG. 6 based on the air flow Va calculated by the expression (3). Based on the wind speed U_i at the time of non-frosting determined from the equation (7), the current wind velocity U of the air flowing through the evaporator 5 is calculated by the equation (5).

  Moreover, if the passage area through which air effectively passes through the current evaporator 5 is S, this passage area S is expressed by the following equation (8), where the current frost layer thickness is t_frost.

  S = W × H− (tf + 2 × t_frost) × H × W / fp (8)

  Further, the wind speed U is expressed by the following equation (9) as in the above equation (7).

  U = Va / S (9)

  Here, from Formula (8) and Formula (9), the frost layer thickness t_frost is represented by the following Formula (10).

t_frost = (U × H × W × fp−U × H × W × tf−Va × fp) / ( 2 × U × H × W ) (10)

  The computing unit 102 calculates the frost layer thickness t_frost from the equation (10) based on the air volume Va calculated by the above equation (3) and the wind speed U calculated by the equation (5).

(S6)
The calculating part 102 determines whether the frost layer thickness t_frost calculated in step S5 has grown to the predetermined threshold value. Specifically, when the arithmetic unit 102 determines that the frost layer thickness t_frost is equal to or greater than a predetermined threshold value, the calculation unit 102 proceeds to step S7. On the other hand, when it determines with frost layer thickness t_frost being less than a predetermined threshold value, it returns to step S4.
In addition, as said threshold value, you may be set as the frost layer thickness reduced to 90% of the capability at the time of non-frosting, for example.
In the above determination, the threshold value determination is performed for the frost layer thickness t_frost. However, the present invention is not limited to this. For example, the calculation unit 102 calculates the fin blockage rate by the following equation (11). It is also possible to calculate fb and determine the threshold value for this fin blockage rate fb.

  fb = 2 × t_frost / (fp−tf) × 100 (11)

(S7)
The control unit 100 starts the defrosting operation.

(Effect of Embodiment 1)
Since the frost layer thickness is calculated for the frost adhering to the evaporator 5 and the start determination of the defrosting operation is performed based on the frost layer thickness as in the above configuration and operation, the compressor frequency Even when the operating state of the heat pump device changes due to changes, load fluctuations, etc., erroneous determination can be prevented in the start determination of the defrosting operation.
Moreover, the addition of a special sensor or the like for detecting the frost layer thickness can be eliminated.

In the present embodiment, the so-called reverse defrosting in which the defrosting operation is performed by switching the four-way valve 2 has been described. However, the present invention is not limited to this, and a heater is installed in the evaporator 5 to remove it. At the time of frost operation, it is good also as what is called heater defrost which melts frost with the heater. Moreover, it is good also as what is called hot gas defrost which flows the high-temperature / high pressure gaseous refrigerant discharged from the compressor 1 directly to the evaporator 5 and performs defrosting without passing through the four-way valve 2. Furthermore, it is good also as what is called off cycle defrost which promotes melt | dissolution of the frost of the evaporator 5 by stopping a normal driving | operation.
Moreover, in this Embodiment, although the calculating part 102 shall calculate the evaporation temperature Te based on the evaporation pressure Pe detected by the evaporator refrigerant | coolant pressure detection means 9, it is not limited to this. Alternatively, an evaporating temperature detecting means for detecting the evaporating temperature Te in the evaporator 5 may be provided.

Embodiment 2. FIG.
The heat pump device according to the present embodiment will be described focusing on differences from the configuration and operation of the heat pump device according to the first embodiment.

(Configuration of heat pump device)
The configuration of the heat pump device according to the present embodiment is the same as the configuration of the heat pump device according to the first embodiment shown in FIG.

FIG. 8 is a block diagram of a control system in the heat pump apparatus according to Embodiment 2 of the present invention.
As shown in FIG. 8, the control unit 100 of the heat pump device according to the present embodiment includes a timer 103 that counts the time until the start determination operation of the defrosting operation is performed. Other configurations are the same as those of the control unit 100 according to the first embodiment shown in FIG.

(Start determination operation of defrosting operation of heat pump device)
FIG. 9 is a flowchart showing the start determination operation of the defrosting operation of the heat pump apparatus according to Embodiment 2 of the present invention. Hereinafter, the start determination operation of the defrosting operation of the heat pump device according to the present embodiment will be described with reference to FIGS. 9 and 10.

(S11)
First, the control unit 100 starts normal operation. At this time, the timer 103 of the control unit 100 starts counting an elapsed time after starting normal operation (hereinafter referred to as “elapsed time before start of determination”).

(S12)
The control unit 100 determines whether the elapsed time before determination start counted by the timer 103 has passed the determination start time τ1. If the control unit 100 determines that the elapsed time before determination start has passed the determination start time τ1, the control unit 100 proceeds to step S13. On the other hand, when it is determined that the elapsed time before determination start has not passed the determination start time τ1, it is continuously monitored whether the elapsed time before determination start has passed the determination start time τ1.

Here, the determination start time τ1 may be set to a time (for example, 10 minutes) at which the refrigeration cycle is sufficiently stabilized after the normal operation is started. Thereby, it is possible to avoid the start determination operation at the timing when the refrigeration cycle is not stable, and the accuracy of the start determination operation can be improved.
In addition, when the time for which the refrigeration cycle is sufficiently stabilized is shorter than 10 minutes, the determination start time τ1 may be set short. Conversely, when it is longer than 10 minutes, the determination start time τ1 is set long. Also good.

(S13)
After the elapse of the determination start time τ1 from the start of the normal operation, the control unit 100 performs the evaporator suction air temperature Ta detected by the evaporator suction air temperature detection means 8 and the evaporation detected by the evaporator refrigerant pressure detection means 9. Pressure Pe, condensing pressure Pc detected by the condenser refrigerant pressure detecting means 10, expansion valve opening P detected by the expansion valve opening detecting means 11, and expansion valve detected by the expansion valve inlet refrigerant temperature detecting means 12. The inlet temperature Tsc is received. Based on the evaporation pressure Pe, the condensation pressure Pc, the expansion valve opening P, and the expansion valve inlet temperature Tsc, the calculation unit 102 of the control unit 100 calculates the refrigerant flow rate Gr at the time when the determination start time τ1 has elapsed according to the equation (1). calculate. And the calculating part 102 calculates evaporation temperature Te based on said evaporation pressure Pe.

(S14)
In step S13, the computing unit 102 stores the evaporator suction air temperature Ta detected by the evaporator suction air temperature detection means 8 as Ta_i, the calculated evaporation temperature Te as Te_i, and the calculated refrigerant flow rate Gr as Gr_i. To remember. At this time, the timer 103 counts the elapsed time after setting the evaporator intake air temperature Ta_i, the evaporation temperature Te_i, and the refrigerant flow rate Gr_i (hereinafter referred to as “elapsed time before calculation of frost layer thickness”). To start.

(S15)
The controller 100 determines whether or not the frost layer thickness calculation elapsed time counted by the timer 103 has passed the defrost prohibition time τ2. When it is determined that the elapsed time before calculation of the frost layer thickness has passed the defrosting prohibition time τ2, the control unit 100 proceeds to step S16. On the other hand, if it is determined that the elapsed time before the frost layer thickness calculation has not passed the defrost prohibition time τ2, then whether or not the elapsed time before the frost layer thickness calculation has passed the defrost prohibition time τ2 is determined. Monitor.

  Here, the defrosting prohibition time τ2 may be set based on the previous defrosting operation time, or may be set based on the frost layer thickness immediately before the start of the previous defrosting operation, for example. . Thereby, based on the last driving | running condition, the start determination of a defrost operation can be implemented at an appropriate timing. Moreover, by providing the defrost prohibition time τ2 as described above, it is possible to avoid the start of the defrost operation due to an erroneous determination.

When the defrosting prohibition time τ2 is set based on the previous defrosting operation time, the control unit 100 determines that the amount of frost formation in the current evaporator 5 is large when the previous defrosting operation time is long. Then, the defrosting prohibition time τ2 is set short. On the other hand, when the last defrosting operation time is short, the control unit 100 determines that the amount of frost formation in the current evaporator 5 is also small, and sets the defrosting prohibition time τ2 to be long. For example, when the last defrosting operation time is 2 minutes or less, the control unit 100 sets the defrosting prohibition time τ2 to 60 minutes because the amount of frost formation is small, while the previous defrosting operation time is 2 When it is longer than minutes, the amount of frost formation is large, so the defrosting prohibition time τ2 is set to 30 minutes.
As described above, the control unit 100 learns from the previous defrosting operation time and sets the defrosting prohibition time τ2, in addition to the defrosting prohibition time τ2 in advance, the defrosting method in the defrosting operation, Or it is good also as what sets based on the individual apparatus characteristic of a heat pump apparatus.

Further, when the defrosting prohibition time τ2 is set based on the frost layer thickness immediately before the start of the previous defrosting operation, the control unit 100 calculates the above-described equation (11) immediately before the start of the previous defrosting operation. When the fin closing rate fb to be performed is large, it is determined that the amount of frost formation in the current evaporator 5 is large, and the defrosting prohibition time τ2 is set short. On the other hand, when the fin blockage rate fb calculated by the equation (11) is small immediately before the start of the previous defrosting operation, the control unit 100 determines that the amount of frost formation in the current evaporator 5 is also small, The defrosting prohibition time τ2 is set longer. For example, when the previous fin blockage rate fb is 50% or less, the control unit 100 sets the defrosting prohibition time τ2 to 60 minutes because the frost formation amount is small, while the previous fin blockage rate fb is 50. When it is larger than%, since the amount of frost formation is large, the defrosting prohibition time τ2 is set to 30 minutes.
In addition, as described above, the control unit 100 learns from the fin blockage rate fb indicating the frost layer thickness immediately before the start of the previous defrosting operation and sets the defrosting prohibition time τ2 in addition to the defrosting prohibition in advance. The time τ2 may be set based on the defrosting method in the defrosting operation or the individual device characteristics of the heat pump device.

(S16)
After the defrosting prohibition time τ2 has elapsed, the control unit 100 receives the evaporator intake air temperature Ta, the evaporation pressure Pe, the condensation pressure Pc, the expansion valve opening degree P, and the expansion valve inlet temperature Tsc from each detection means at that time. . Based on the evaporation pressure Pe, the condensation pressure Pc, the expansion valve opening P, and the expansion valve inlet temperature Tsc, the calculation unit 102 calculates the refrigerant flow rate Gr at the time when the defrosting prohibition time τ2 has elapsed according to the equation (1). And the calculating part 102 calculates evaporation temperature Te based on said evaporation pressure Pe.

(S17)
The calculation unit 102 calculates the frost layer thickness t_frost when the defrosting prohibition time τ <b> 2 has elapsed in the evaporator 5, similarly to the process of step S <b> 5 in the first embodiment.

(S18)
The calculating part 102 determines whether the frost layer thickness t_frost calculated in step S17 has grown to the predetermined threshold value. Specifically, when the arithmetic unit 102 determines that the frost layer thickness t_frost is equal to or greater than a predetermined threshold value, the calculation unit 102 proceeds to step S20. On the other hand, when it determines with frost layer thickness t_frost being less than a predetermined threshold value, it progresses to step S19.
In addition, as said threshold value, you may be set as the frost layer thickness reduced to 90% of the capability at the time of non-frosting, for example.
In the above determination, the threshold value determination is performed for the frost layer thickness t_frost. However, the present invention is not limited to this. For example, the calculation unit 102 calculates the fin blockage rate fb according to Equation (11). It is also possible to calculate and determine the threshold value for the fin blockage rate fb.

(S19)
The control unit 100 determines whether or not the frost layer thickness calculation elapsed time counted by the timer 103 has passed the maximum operation time τ3. When it is determined that the elapsed time before calculation of the frost layer thickness has passed the maximum operation time τ3, the control unit 100 proceeds to step S20. On the other hand, if it is determined that the elapsed time before the frost layer thickness calculation has not exceeded the maximum operation time τ3, the process returns to step S16.

  Here, the maximum operation time τ3 may be set, for example, based on the previous defrosting operation time, or may be set based on the frost layer thickness immediately before the start of the previous defrosting operation. As a result, it is possible to avoid a situation in which the defrosting operation is not performed due to an erroneous determination.

When the operation maximum time τ3 is set based on the previous defrosting operation time, the control unit 100 determines that the amount of frost formation in the current evaporator 5 is large when the previous defrosting operation time is long. Thus, the maximum operation time τ3 is set short. On the other hand, when the last defrosting operation time is short, the control unit 100 determines that the amount of frost formation in the current evaporator 5 is also small, and sets the maximum operation time τ3 to be long. For example, when the last defrosting operation time is 2 minutes or less, the control unit 100 sets the maximum operation time τ3 to 240 minutes because the amount of frost formation is small, while the previous defrosting operation time is 2 minutes. In the case where it is longer than this, since the amount of frost formation is large, the operation maximum time τ3 is set to 120 minutes.
As described above, the control unit 100 learns from the previous defrosting operation time and sets the operation maximum time τ3, in addition to the operation maximum time τ3 in advance, the defrosting method in the defrosting operation, or It is good also as what sets based on the individual apparatus characteristic of a heat pump apparatus.

When setting the maximum operation time τ3 based on the frost layer thickness immediately before the start of the previous defrosting operation, the control unit 100 is calculated by the above-described equation (11) immediately before the start of the previous defrosting operation. When the fin closing rate fb is large, it is determined that the amount of frost formation in the current evaporator 5 is also large, and the maximum operation time τ3 is set short. On the other hand, when the fin blockage rate fb calculated by the equation (11) is small immediately before the start of the previous defrosting operation, the control unit 100 determines that the amount of frost formation in the current evaporator 5 is also small, Set the maximum operation time τ3 longer. For example, when the previous fin blockage rate fb is 50% or less, the control unit 100 sets the maximum operation time τ3 to 240 minutes because the amount of frost formation is small, while the previous fin blockage rate fb is 50%. Is larger, the maximum frosting amount is set, so the maximum operation time τ3 is set to 120 minutes.
Note that, as described above, the control unit 100 learns from the fin blockage rate fb indicating the frost layer thickness immediately before the start of the previous defrosting operation and sets the operation maximum time τ3, or in advance the operation maximum time τ3. May be set based on the defrosting method in the defrosting operation or the individual device characteristics of the heat pump device.
(S20)
The control unit 100 starts the defrosting operation.

(Effect of Embodiment 2)
As in the above configuration and operation, the start determination operation is performed at a timing when the refrigeration cycle is not stabilized by providing the determination start time τ1 that is the time from the start of normal operation until the refrigeration cycle is sufficiently stabilized. Can be avoided, and the accuracy of the start determination operation can be improved.
In addition, by providing the defrosting prohibition time τ2 before calculating the frost layer thickness t_frost in the evaporator 5, it is possible to avoid the start of the defrosting operation due to erroneous determination. In addition, the defrosting operation start determination is made by setting the defrosting prohibition time τ2 based on the previous defrosting operation time or the previous operation state such as the frost layer thickness immediately before the start of the previous defrosting operation. It can be implemented at an appropriate timing.
Furthermore, by providing the maximum operation time τ3 that is the maximum time until the start of the defrosting operation, it is possible to avoid a situation in which the defrosting operation is not performed due to an erroneous determination.

  In addition, when learning and calculating said defrosting prohibition time (tau) 2 or driving | operation maximum time (tau) 3 from the last driving | running condition, it is good also as what is calculated as follows, for example. First, as shown in FIG. 10, assuming that the normal operation time and the frost layer thickness of the evaporator 5 are in a proportional relationship, the calculation unit 102 calculates the previous normal operation time τ 0 and immediately before the start of the defrost operation at that time. The frost layer thickness growth rate Vtf is calculated from the following equation (12) using the frost layer thickness t_frost0.

  Vtf = t_frost0 / τ0 (12)

  Then, based on the calculated frost layer thickness growth rate Vtf, the calculation unit 102 calculates, for example, a time until the fin layer thickness fb reaches 50% and grows to a frost layer thickness, and removes the time. It is good also as what is set to frost prohibition time (tau) 2. Further, based on the calculated frost layer thickness growth rate Vtf, the calculation unit 102 calculates, for example, the time until the frost layer thickness where the fin blockage rate fb is 90% and grows, and operates the time. The maximum time τ3 may be set.

  In this way, by setting the defrosting prohibition time τ2 by changing the amount of frost formation in the evaporator 5, it is possible to start unnecessary determinations and minimize the start of determination, and more accurately. A high determination can be made. In addition, by setting the operation maximum time τ3 by changing the amount of frost formation in the evaporator 5, not only the situation where the defrosting operation is not performed due to an erroneous determination can be avoided, but an appropriate operation maximum time τ3 can be set, Useless defrosting operation can be avoided.

  Further, in the operation of the heat pump device according to the present embodiment, the timer 103 determines the elapsed time before calculating the frost layer thickness after the evaporator intake air temperature Ta_i, the evaporation temperature Te_i, and the refrigerant flow rate Gr_i are set in step S14. However, the present invention is not limited to this, and may be an operation that starts counting after normal operation is started, such as the elapsed time before the start of determination.

  Furthermore, in the operation of the heat pump device according to the present embodiment, by providing the determination start time τ1, the refrigeration cycle is stabilized after the normal operation is started, and by providing the defrosting prohibition time τ2, the frost layer The time until the thickness t_frost is calculated is set, and the upper limit value of the elapsed time until the defrosting operation is started is set by providing the operation maximum time τ3. These determination start times τ1, The present invention is not limited to providing all of the defrosting prohibition time τ2 and the maximum operation time τ3, and any one of them may be provided.

Embodiment 3 FIG.
The heat pump apparatus according to the present embodiment will be described focusing on differences from the configuration and operation of the heat pump apparatus according to the first and second embodiments.

(Configuration of heat pump device)
FIG. 11 is a configuration diagram of the evaporator 5 of the heat pump device according to Embodiment 3 of the present invention.
As shown in FIG. 11, wind speed detecting means 21 is installed in the vicinity of the surface into which air enters in evaporator 5 according to the present embodiment. The wind speed detection means 21 is connected to the control unit 100, detects the wind speed of the air passing through the evaporator 5, and transmits the wind speed information to the control unit 100. Further, the heat pump device according to the present embodiment includes an evaporator suction air temperature detection means 8, an evaporator refrigerant pressure detection means 9, and a condenser refrigerant pressure detection means 10 in the heat pump device according to the first or second embodiment. The expansion valve opening degree detection means 11 and the expansion valve inlet refrigerant temperature detection means 12 are not provided. Other configurations are the same as those of the heat pump device according to the first and second embodiments.

(Start determination operation of defrosting operation of heat pump device)
With the configuration as described above, the calculation unit 102 of the control unit 100 calculates the passage area through which air passes through the front surface where air enters in the evaporator 5 from the width W and the height H shown in FIG. Based on the area and the wind speed detected by the wind speed detecting means 21, the air volume Va can be easily calculated without using the equation (3).

(Effect of Embodiment 3)
With the above configuration, the calculation unit 102 calculates the air volume Va from the evaporation temperature Te and the evaporator refrigerant pressure detected by the evaporator intake air temperature detection means 8 as in the heat pump device according to the first or second embodiment. The evaporator suction air temperature Ta detected by the detection means 9, the condensation pressure Pc detected by the condenser refrigerant pressure detection means 10, the expansion valve opening P detected by the expansion valve opening detection means 11, and the expansion valve inlet It can be calculated without using the expansion valve inlet temperature Tsc detected by the refrigerant temperature detecting means 12. Therefore, the evaporator suction air temperature detection means 8, the evaporator refrigerant pressure detection means 9, the condenser refrigerant pressure detection means 10, and the expansion valve opening degree detection means 11 as in the heat pump device according to the first or second embodiment. In addition, the expansion valve inlet refrigerant temperature detection means 12 can be eliminated, and as a whole, the number of detection means can be reduced by four compared to the heat pump device according to the first or second embodiment. .

  As described above, the evaporator intake air temperature detection means 8, the evaporator refrigerant pressure detection means 9, the condenser refrigerant pressure detection means 10, the expansion valve opening degree detection means 11, and the expansion valve inlet refrigerant temperature detection means 12 are provided. These are not necessary to calculate the air volume Va, but needless to say, they may be provided if they are used for other purposes.

Embodiment 4 FIG.
The heat pump apparatus according to the present embodiment will be described focusing on differences from the configuration and operation of the heat pump apparatus according to the first and second embodiments.

(Configuration of heat pump device)
FIG. 12 is a configuration diagram of the evaporator 5 and the evaporator fan 7 of the heat pump apparatus according to Embodiment 4 of the present invention.
As shown in FIG. 12, the fan input detecting means 22 is built in the evaporator fan 7 according to the present embodiment. The fan input detection unit 22 is connected to the control unit 100, detects a current that flows when the evaporator fan 7 is rotationally driven, and transmits the current information to the control unit 100. Further, the heat pump device according to the present embodiment includes an evaporator suction air temperature detection means 8, an evaporator refrigerant pressure detection means 9, and a condenser refrigerant pressure detection means 10 in the heat pump device according to the first or second embodiment. The expansion valve opening degree detection means 11 and the expansion valve inlet refrigerant temperature detection means 12 are not provided. Other configurations are the same as those of the heat pump device according to the first and second embodiments.

(Start determination operation of defrosting operation of heat pump device)
With the configuration as described above, the calculation unit 102 of the control unit 100 tries to obtain the same fan rotation speed when frosting progresses in the evaporator 5 and the ventilation resistance increases and the pressure loss increases accordingly. Then, since the current flowing through the evaporator fan 7 increases, the pressure loss ΔP is obtained from the relationship between the pressure loss and the current value. Based on the pressure loss ΔP, the air volume Va is obtained from the relationship shown in FIG. Can be requested.

(Effect of Embodiment 4)
With the above configuration, the calculation unit 102 calculates the air volume Va from the evaporation temperature Te and the evaporator refrigerant pressure detected by the evaporator intake air temperature detection means 8 as in the heat pump device according to the first or second embodiment. The evaporator suction air temperature Ta detected by the detection means 9, the condensation pressure Pc detected by the condenser refrigerant pressure detection means 10, the expansion valve opening P detected by the expansion valve opening detection means 11, and the expansion valve inlet It can be obtained without using the expansion valve inlet temperature Tsc detected by the refrigerant temperature detecting means 12. Therefore, the evaporator suction air temperature detection means 8, the evaporator refrigerant pressure detection means 9, the condenser refrigerant pressure detection means 10, and the expansion valve opening degree detection means 11 as in the heat pump device according to the first or second embodiment. In addition, the expansion valve inlet refrigerant temperature detection means 12 can be eliminated, and as a whole, the number of detection means can be reduced by four compared to the heat pump device according to the first or second embodiment. .

  As described above, the evaporator intake air temperature detection means 8, the evaporator refrigerant pressure detection means 9, the condenser refrigerant pressure detection means 10, the expansion valve opening degree detection means 11, and the expansion valve inlet refrigerant temperature detection means 12 are provided. These are not necessary to calculate the air volume Va, but needless to say, they may be provided if they are used for other purposes.

Embodiment 5 FIG.
The heat pump apparatus according to the present embodiment will be described focusing on differences from the configuration and operation of the heat pump apparatus according to the first and second embodiments.

(Configuration of heat pump device)
FIG. 13 is a schematic configuration diagram of a refrigerant circuit of a heat pump device according to Embodiment 5 of the present invention.
As shown in FIG. 13, the heat pump device according to the present embodiment includes a compressor suction refrigerant temperature detection means 23 and a compressor suction refrigerant pressure detection means 24 in the refrigerant pipe on the suction side of the compressor 1. The compressor suction refrigerant temperature detection means 23 and the compressor suction refrigerant pressure detection means 24 are connected to the control unit 100. Among these, the compressor suction refrigerant temperature detection means 23 detects the temperature of the refrigerant sucked into the compressor 1 and transmits the temperature information to the control unit 100. The compressor suction refrigerant pressure detection means 24 detects the pressure of the refrigerant sucked into the compressor 1 and transmits the pressure information to the control unit 100. Further, the heat pump device according to the present embodiment includes the condenser refrigerant pressure detection means 10, the expansion valve opening degree detection means 11, and the expansion valve inlet refrigerant temperature detection means 12 in the heat pump device according to the first embodiment or the second embodiment. Is not provided. Other configurations are the same as those of the heat pump device according to the first and second embodiments.

(Start determination operation of defrosting operation of heat pump device)
With the configuration as described above, the calculation unit 102 of the control unit 100 is detected by the compressor intake refrigerant temperature detection means 23 without depending on the expansion valve opening P or the like as shown in the above-described equation (1). The density of the refrigerant sucked into the compressor 1 is calculated based on the refrigerant temperature and the refrigerant pressure detected by the compressor suction refrigerant pressure detecting means 24, and the refrigerant density, the frequency of the compressor 1, and the excluded volume are calculated. Based on this, the refrigerant flow rate Gr is calculated.

(Effect of Embodiment 5)
Since the calculation unit 102 can calculate the refrigerant flow rate Gr by providing the compressor intake refrigerant temperature detection unit 23 and the compressor intake refrigerant pressure detection unit 24 as described above, Embodiment 1 Alternatively, the condenser refrigerant pressure detection means 10, the expansion valve opening degree detection means 11 and the expansion valve inlet refrigerant temperature detection means 12 as in the heat pump device according to the second embodiment can be dispensed with. Compared to the heat pump device according to the first or second embodiment, the number of detection means can be reduced by one.

  As described above, the condenser refrigerant pressure detecting means 10, the expansion valve opening degree detecting means 11, and the expansion valve inlet refrigerant temperature detecting means 12 are not provided, but these are used for calculating the refrigerant flow rate Gr. Needless to say, it may be provided if it is used for other purposes.

Embodiment 6 FIG.
The heat pump apparatus according to the present embodiment will be described focusing on differences from the configuration and operation of the heat pump apparatus according to the first and second embodiments.

(Configuration of heat pump device)
FIG. 14 is a schematic configuration diagram of a refrigerant circuit of a heat pump device according to Embodiment 6 of the present invention.
As shown in FIG. 14, the heat pump device according to the present embodiment includes a refrigerant flow meter 25 between the condenser 3 and the expansion valve 4. The refrigerant flow meter 25 is connected to the control unit 100, detects the flow rate of the liquid refrigerant flowing out from the condenser 3, and transmits the refrigerant flow rate information to the control unit 100. Further, the heat pump device according to the present embodiment includes the condenser refrigerant pressure detection means 10, the expansion valve opening degree detection means 11, and the expansion valve inlet refrigerant temperature detection means 12 in the heat pump device according to the first embodiment or the second embodiment. Is not provided. Other configurations are the same as those of the heat pump device according to the first and second embodiments.

  The refrigerant flow meter 25 corresponds to “refrigerant flow rate detecting means” of the present invention.

(Start determination operation of defrosting operation of heat pump device)
With the configuration as described above, the calculation unit 102 of the control unit 100 can directly obtain the refrigerant flow rate Gr from the refrigerant flow meter 25 without depending on the expansion valve opening P or the like as shown in the above-described equation (1). Can do.

(Effect of Embodiment 6)
Since the refrigerant flow meter 25 is provided as described above, the calculation unit 102 can directly obtain the refrigerant flow rate Gr, so that the condensation in the heat pump device according to the first embodiment or the second embodiment is performed. The refrigerant pressure detection means 10, the expansion valve opening degree detection means 11, and the expansion valve inlet refrigerant temperature detection means 12 can be eliminated, and as a whole, compared with the heat pump device according to the first or second embodiment. Thus, the number of detection means can be reduced by two.

  As described above, the condenser refrigerant pressure detecting means 10, the expansion valve opening degree detecting means 11, and the expansion valve inlet refrigerant temperature detecting means 12 are not provided, but these are not necessary for obtaining the refrigerant flow rate Gr. That is, it goes without saying that it may be provided if it is used for other purposes.

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Four way valve, 3 Condenser, 4 Expansion valve, 5 Evaporator, 6 Condenser fan, 6a Condenser fan motor, 7 Evaporator fan, 7a Evaporator fan motor, 8 Evaporator intake air temperature detection means , 9 Evaporator refrigerant pressure detection means, 10 Condenser refrigerant pressure detection means, 11 Expansion valve opening degree detection means, 12 Expansion valve inlet refrigerant temperature detection means, 21 Wind speed detection means, 22 Fan input detection means, 23 Compressor suction refrigerant Temperature detection means, 24 compressor intake refrigerant pressure detection means, 25 refrigerant flow meter, 100 control unit, 101 memory, 102 calculation unit, 103 timer.

Claims (15)

A refrigerant circuit in which a compressor, a condenser, an expansion device, and an evaporator are annularly connected by a refrigerant pipe;
Evaporator temperature detecting means for detecting a saturation temperature of the refrigerant of the evaporator (hereinafter referred to as "evaporation temperature");
An evaporator suction air temperature detection means for detecting a temperature of air sent to the evaporator (hereinafter referred to as “evaporator suction air temperature”);
Refrigerant flow rate detecting means for detecting the flow rate of the refrigerant flowing through the refrigerant circuit;
A control unit that performs a defrosting operation start determination as to whether or not to start the defrosting operation;
With
The control unit
Based on the evaporation temperature detected by the evaporator temperature detection means, the evaporator intake air temperature detected by the evaporator intake air temperature detection means, and the refrigerant flow rate detected by the refrigerant flow detection means, Calculating the volume of air passing through the evaporator,
From the air volume, the pressure loss is derived based on a predetermined relationship between the pressure loss of the air passing through the evaporator and the air volume,
From the pressure loss, the air volume at the time of no frost formation, and the pressure loss at the time of no frost formation derived from the air volume based on the predetermined relationship, the wind speed of the air passing through the evaporator is calculated,
Based on the calculated air volume and the wind speed, the thickness of frost generated in the evaporator (hereinafter referred to as “frost layer thickness”) is calculated,
When the frost layer thickness is equal to or greater than a predetermined threshold, the defrosting operation is performed .
When the frost layer thickness is t_frost, the air volume is Va, the wind speed is U, the evaporator height is H, the width is W, the fin plate thickness is tf, and the fin pitch is fp, the air volume Va and the Based on the wind speed U, the frost layer thickness t_frost is calculated by the following formula.
t_frost = (U × H × W × fp−U × H × W × ft−Va × fp) / (2 × U × H × W) A refrigerant circuit in which a compressor, a condenser, an expansion device, and an evaporator are annularly connected by a refrigerant pipe;
Evaporator temperature detecting means for detecting a saturation temperature of the refrigerant of the evaporator (hereinafter referred to as "evaporation temperature");
An evaporator suction air temperature detection means for detecting a temperature of air sent to the evaporator (hereinafter referred to as “evaporator suction air temperature”);
Compressor intake refrigerant temperature detection means for detecting the temperature of refrigerant sucked into the compressor (hereinafter referred to as “compressor refrigerant temperature”);
Compressor suction refrigerant pressure detection means for detecting the pressure of refrigerant sucked into the compressor (hereinafter referred to as “compressor refrigerant pressure”);
Compressor frequency detecting means for detecting the frequency of the compressor;
A control unit that performs a defrosting operation start determination as to whether or not to start the defrosting operation;
With
The control unit
The density of the refrigerant sucked into the compressor based on the compressor refrigerant temperature detected by the compressor intake refrigerant temperature detection means and the compressor refrigerant pressure detected by the compressor intake refrigerant pressure detection means To calculate
Based on the refrigerant density, the frequency of the compressor detected by the compressor frequency detecting means, and the excluded volume of the compressor, the flow rate of the refrigerant flowing through the refrigerant circuit is calculated,
Based on the refrigerant flow rate, the evaporation temperature detected by the evaporator temperature detecting means, and the evaporator suction air temperature detected by the evaporator suction air temperature detecting means, the air volume passing through the evaporator To calculate
From the air volume, the pressure loss is derived based on a predetermined relationship between the pressure loss of the air passing through the evaporator and the air volume,
From the pressure loss, the air volume at the time of no frost formation, and the pressure loss at the time of no frost formation derived from the air volume based on the predetermined relationship, the wind speed of the air passing through the evaporator is calculated,
Based on the calculated air volume and the wind speed, the thickness of frost generated in the evaporator (hereinafter referred to as “frost layer thickness”) is calculated,
When the frost layer thickness is equal to or greater than a predetermined threshold, the defrosting operation is performed .
When the frost layer thickness is t_frost, the air volume is Va, the wind speed is U, the evaporator height is H, the width is W, the fin plate thickness is tf, and the fin pitch is fp, the air volume Va and the Based on the wind speed U, the frost layer thickness t_frost is calculated by the following formula.
t_frost = (U × H × W × fp−U × H × W × ft−Va × fp) / (2 × U × H × W) The refrigerant flow rate detection means is
Evaporator refrigerant pressure detection means for detecting refrigerant pressure (hereinafter referred to as “evaporation pressure”) of the evaporator, and condenser refrigerant pressure detection for detecting refrigerant pressure (hereinafter referred to as “condensation pressure”) of the condenser. Means for detecting the opening of the expansion device (hereinafter referred to as “expansion device opening”), and the temperature at the inlet of the expansion device (hereinafter referred to as “expansion device inlet temperature”). An expansion device inlet refrigerant temperature detection means for detecting,
The evaporating pressure detected by the evaporator refrigerant pressure detecting means, the condensing pressure detected by the condenser refrigerant pressure detecting means, the expansion device opening detected by the expansion device opening detecting means, and the expansion The heat pump device according to claim 1, wherein the refrigerant flow rate is calculated based on the expansion device inlet temperature detected by the device inlet refrigerant temperature detection means. In place of the evaporator temperature detecting means, an evaporator refrigerant pressure detecting means for detecting a refrigerant pressure of the evaporator (hereinafter referred to as “evaporating pressure”) is provided.
The heat pump device according to claim 1, wherein the control unit calculates the evaporation temperature based on the evaporation pressure detected by the evaporator refrigerant pressure detection unit. An evaporator fan for sending air to the evaporator;
In place of the evaporator suction air temperature detection means and the evaporator refrigerant pressure detection means, the fan input detection means is installed in the evaporator fan and detects a current accompanying the rotational drive of the evaporator fan,
The controller is
Based on the current value detected by the fan input detection means, calculate the pressure loss of the air passing through the evaporator,
Based on the pressure loss, calculate the air volume of the air passing through the evaporator,
The heat pump apparatus according to claim 3 or 4, wherein a wind speed of air passing through the evaporator is calculated based on the air volume. The controller is
It has a timer that counts time,
The heat pump device according to any one of claims 1 to 5, wherein the defrosting operation start determination is performed based on a time counted by the timer. The timer counts the elapsed time from the start of normal operation by the control unit,
The heat pump device according to claim 6, wherein the controller performs the defrosting operation start determination after the elapsed time has passed a preset determination start time. The timer counts the elapsed time from the start of normal operation by the control unit,
In the defrosting operation start determination, the control unit calculates the frost layer thickness after the elapsed defrost prohibition time has elapsed, and the frost layer thickness is equal to or greater than a predetermined threshold value. The heat pump apparatus according to claim 6 or 7, wherein whether or not there is present is determined. The heat pump device according to claim 8, wherein the control unit sets the defrosting prohibition time based on a previous defrosting operation time. The heat pump device according to claim 8, wherein the control unit sets the defrosting prohibition time based on a frost layer thickness immediately before the start of the previous defrosting operation. The heat pump device according to claim 8, wherein the controller sets the defrosting prohibition time based on a frost layer thickness immediately before the start of the previous defrosting operation and a previous normal operation time. The timer counts the elapsed time from the start of normal operation by the control unit,
The heat pump device according to any one of claims 6 to 11, wherein the control unit forcibly performs a defrosting operation after the elapsed time has passed a preset operation maximum time. . The heat pump device according to claim 12, wherein the control unit sets the operation maximum time based on a previous defrosting operation time. The heat pump device according to claim 12, wherein the control unit sets the maximum operation time based on a frost layer thickness immediately before the start of a previous defrost operation. The heat pump device according to claim 12, wherein the control unit sets the operation maximum time based on a frost layer thickness immediately before the start of a previous defrost operation and a previous normal operation time.

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