JP6190577B2 - Heat pump frost determination method and heat pump using the method - Google Patents

Description

The present invention relates to a heat pump frost determination method for detecting the occurrence of frost in an evaporator of a heat pump and a heat pump employing the method.

The heat pump includes a metal fin having excellent thermal conductivity as an evaporator which is a heat exchanger, and takes heat of outside air into the refrigerant flowing inside the fin through the fin to vaporize the refrigerant. When frost is generated on the surface of the fin (hereinafter also referred to as “the surface of the evaporator”), the heat absorption efficiency from the outside air of the evaporator is reduced. Therefore, the heat pump is provided with a defrosting operation mode to the surface of the evaporator. When frost formation is detected, defrosting operation is performed to remove frost on the surface of the evaporator.

While performing the defrosting operation, the heat pump cannot perform the original work, that is, the work of boiling the hot water in the hot water storage tank or heating the room, so the defrosting operation is completed in a short time. Is desirable.
And as the frosting on the evaporator surface progresses, it takes a long time for the defrosting operation. To shorten the time for the defrosting operation, the defrosting operation is performed before the frosting on the evaporator surface proceeds. It is effective to start. Therefore, it is important to accurately detect the timing at which frost formation on the evaporator surface has started, and a specific example of a method for detecting the timing at which frost formation on the evaporator surface has occurred is described in Patent Document 1. ing.

The method of Patent Document 1 calculates an integrated average value of the boiling capacity of hot water by a heat pump every predetermined time, and when this integrated average value decreases continuously a predetermined number of times, frosting on the evaporator surface starts. It is determined that This is a method that pays attention to the fact that when frost is generated on the evaporator surface and the heat exchange efficiency is lowered, the boiling capacity of hot water is also lowered.

JP 2003-222392 A

However, the inventors of the present application have confirmed that in the method of Patent Document 1, although frost is generated on the surface of the evaporator, frost formation on the evaporator may not be detected.
This is because when the frosting speed is moderate, the integrated average value of the boiling ability of hot water may not continuously decrease.
Moreover, since the boiling capacity of hot water is an estimated value, it does not necessarily match the actual value, and it is considered that frost formation on the evaporator may not be detected accurately. .
This invention is made | formed in view of this situation, and it aims at providing the heat pump which employ | adopted the frost determination method of the heat pump which detects stably the frost on the evaporator surface, and its method.

In the heat pump frost formation determination method according to the first aspect of the present invention, an frost is disposed in an evaporator disposed upstream of the compressor along the refrigerant flow to evaporate the liquid refrigerant by taking in heat from outside air. In the method for determining frost formation of a heat pump for detecting the occurrence of the refrigerant, the length of the flow path through which the refrigerant in the evaporator flows is L, the inlet of the refrigerant in the flow path is 0 position, and the refrigerant in the flow path The temperature obtained by subtracting the temperature of the refrigerant measured between the L / 4 position and the 3L / 4 position from the temperature of the refrigerant flowing into the compressor is equal to or lower than a predetermined temperature ΔT1. When it is maintained for a predetermined time P, it is determined that frost has formed in the evaporator.

The frost formation determination method for a heat pump according to the second aspect of the present invention is directed to an evaporator disposed on the upstream side of a compressor along a refrigerant flow to take in heat from outside air and evaporate the liquid refrigerant. In the method for determining frost formation of a heat pump for detecting the occurrence of the refrigerant, the length of the flow path through which the refrigerant in the evaporator flows is L, the inlet of the refrigerant in the flow path is 0 position, and the refrigerant in the flow path The temperature obtained by subtracting the temperature of the refrigerant measured between the L / 4 position and the 3L / 4 position from the temperature of the refrigerant flowing into the compressor is equal to or lower than a predetermined temperature ΔT1. And the temperature obtained by subtracting the temperature of the refrigerant flowing into the compressor from the outside air temperature is equal to or higher than a predetermined temperature ΔT2 and the outside air temperature is equal to or lower than a predetermined temperature T3. When maintained for a predetermined time P It determines that the frost generated in the evaporator.

A heat pump according to a third aspect of the present invention that includes the above object includes a temperature sensor A that measures the temperature of the refrigerant passing through the evaporator, and a temperature sensor B that measures the temperature of the refrigerant flowing into the compressor, In a heat pump that heats water or air by radiating heat absorbed from outside air by an evaporator to heat water or air, the length of the flow path through which the refrigerant in the evaporator flows is L, and the refrigerant inlet of the flow path The temperature sensor A is disposed between the L / 4 position and the 3L / 4 position, and the temperature sensor A is measured from the temperature measured by the temperature sensor B. When the temperature obtained by subtracting the measured temperature is maintained at a predetermined temperature ΔT1 or less for a predetermined time P, it is determined that frost has occurred in the evaporator.

A heat pump according to a fourth aspect of the present invention that meets the above object includes a temperature sensor A that measures the temperature of the refrigerant passing through the evaporator, a temperature sensor B that measures the temperature of the refrigerant flowing into the compressor, and the temperature of the outside air. A heat pump that heats water or air by radiating heat absorbed from outside air by the evaporator to heat water or air, and a length of a flow path through which the refrigerant in the evaporator flows L, the refrigerant inlet of the flow path is the 0 position, the refrigerant outlet of the flow path is the L position, and the temperature sensor A is disposed between the L / 4 position and the 3L / 4 position, The temperature obtained by subtracting the measured temperature of the temperature sensor A from the measured temperature of the temperature sensor B is equal to or lower than a predetermined temperature ΔT1, and the measured temperature of the temperature sensor B is subtracted from the measured temperature of the temperature sensor C. The temperature is predetermined When the temperature ΔT2 or higher and the temperature measured by the temperature sensor C is not higher than a predetermined temperature T3 is maintained for a predetermined time P, it is determined that frost has occurred in the evaporator. .

The heat pump frost determination method according to the first and second inventions and the heat pump according to the third and fourth inventions are obtained by subtracting the temperature of the refrigerant passing through the evaporator from the temperature of the refrigerant flowing into the compressor. However, when it is maintained at a predetermined temperature ΔT1 or lower for a predetermined time P, it is determined that frost has formed on the evaporator, and therefore, it is stably evaporated regardless of the speed of frost formation on the evaporator surface. It can be determined that frost has formed on the vessel. This has been confirmed by experimental verification.

It is a circuit diagram of the heat pump which employ | adopted the frost formation determination method of the heat pump which concerns on one embodiment of this invention. It is explanatory drawing which shows a defrost operation. It is a graph which shows the time of the defrost operation at the time of employ | adopting the frost formation determination method of the heat pump which concerns on a comparative example. It is a graph which shows the time of the defrost operation at the time of employ | adopting the frost formation determination method of the heat pump which concerns on the Example of this invention.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
As shown in FIG. 1, a heat pump 10 that employs a frosting determination method for a heat pump according to an embodiment of the present invention has a refrigerant circulation in which an evaporator 11, a compressor 12, a radiator 13, and an expansion valve 14 are provided. A circuit 15 is provided, and heat absorbed from the outside air by the evaporator 11 is radiated by the radiator 13 to heat water or air. Details will be described below.

In the present embodiment, as shown in FIG. 1, a hot water storage tank 17 is connected to the heat pump 10 via a hot water circulation circuit 16. The hot water circulation circuit 16 connects the lower part of the hot water storage tank 17, the radiator 13 and the upper part of the hot water storage tank 17, and guides the water in the lower part of the hot water storage tank 17 to the upper part of the hot water storage tank 17 via the radiator 13.
The heat radiator 13 exchanges heat between water sent from the lower part of the hot water storage tank 17 to the heat radiator 13 and refrigerant flowing through the refrigerant circulation circuit 15, and heats water sent from the lower part of the hot water storage tank 17 to the heat radiator 13. Hot water heated by the passage of the radiator 13 flows into the hot water storage tank 17 from the upper part of the hot water storage tank 17 through the hot water circulation circuit 16.

The hot water circulation circuit 16 is provided with a circulation pump 18 that sends water below the hot water storage tank 17 to the radiator 13 and a three-way valve 19 that switches the destination of hot water (meaning hot water or water) that has passed through the radiator 13. ing.
A bypass pipe 20 that connects the three-way valve 19 and the lower part of the hot water storage tank 17 is connected to the three-way valve 19, and the three-way valve 19 switches the destination of hot water according to the temperature of the hot water that has passed through the radiator 13.

Specifically, the three-way valve 19 is configured so that the hot water that has passed through the radiator 13 passes through the bypass pipe 20 when the hot water that has passed through the radiator 13 has a predetermined temperature (40 ° C. in this embodiment) or less. When the hot water passing through the radiator 13 becomes higher than a predetermined temperature, the hot water passing through the radiator 13 is sent to the upper portion of the hot water storage tank 17.
Thus, by switching the destination of the hot water that has passed through the radiator 13, the low temperature water is prevented from flowing into the upper part of the hot water storage tank 17.

The hot water circulation circuit 16 is provided with a temperature sensor 21 for measuring the temperature of water flowing into the radiator 13 and a temperature sensor 22 for measuring the temperature of hot water passing through the radiator 13.
A plurality of temperature sensors 23 are arranged at different height positions of the hot water storage tank 17, and a tank side control device 24 connected to the circulation pump 18 and the three-way valve 19 is connected to the plurality of temperature sensors 23 by signal connection. Has been. The tank side control device 24 is, for example, a microcomputer.

A hot water supply pipe 25 that supplies hot water in the hot water storage tank 17 to the kitchen or bathroom is connected to the upper part of the hot water storage tank 17, and a water pipe that supplies tap water to the hot water storage tank 17 at the lower part of the hot water storage tank 17. 26 are connected.
The temperature sensors 21 and 22 are housed in the housing of the heat pump 10 together with the evaporator 11, the compressor 12, the radiator 13, the expansion valve 14, and the refrigerant circulation circuit 15.

In addition to the radiator 13, the refrigerant circulation circuit 15 includes an expansion valve 14 that decompresses the refrigerant that has passed through the radiator 13, an evaporator 11 that evaporates the decompressed refrigerant and absorbs heat of the outside air, and an evaporator 11. A compressor 12 is provided for compressing the gaseous refrigerant.
The evaporator 11 is disposed on the upstream side of the compressor 12 along the flow of the refrigerant, takes heat from the outside air, and evaporates the liquid refrigerant. In the vicinity of the evaporator 11, a propeller fan 28 that promotes the evaporation of the refrigerant by the evaporator 11 is provided. The evaporator 11 is attached with a temperature sensor 29 (temperature sensor A) for measuring the temperature of the refrigerant passing through the evaporator 11.

The refrigerant that has passed through the evaporator 11 flows into the compressor 12 through an accumulator 30 provided on the front side of the compressor 12. The accumulator 30 removes the liquid refrigerant from the gas-liquid mixed refrigerant when all of the refrigerant that has passed through the evaporator 11 does not become gaseous and the refrigerant is sent from the evaporator 11 in the gas-liquid mixed state. Only the gaseous refrigerant is supplied into the compressor 12.
The liquid refrigerant removed from the gas-liquid mixed refrigerant by the accumulator 30 is stored in the accumulator 30, evaporates with the passage of time, and flows into the compressor 12 as a gas.

The refrigerant in the refrigerant circulation circuit 15 circulates in the refrigerant circulation circuit 15 by the operation of the compressor 12.
The refrigerant circulation circuit 15 is provided with a temperature sensor 31 (temperature sensor B) for measuring the temperature of the refrigerant flowing into the compressor 12 on the upstream side of the accumulator 30, and from the compressor 12 on the downstream side of the compressor 12. A temperature sensor 32 that measures the temperature of the discharged refrigerant is provided.

The refrigerant circulation circuit 15 is provided with a pressure switch 33. When the pressure of the refrigerant that has passed through the compressor 12 exceeds a predetermined value (for example, 13 MPa), the operation of the compressor 12 is stopped and the refrigerant circulation circuit. It is possible to prevent troubles from occurring in the 15 pipes and the devices provided in the refrigerant circulation circuit 15.
The refrigerant circulation circuit 15 is provided with an internal heat exchanger 34 for exchanging heat between the refrigerant sent from the radiator 13 to the expansion valve 14 and the refrigerant sent from the evaporator 11 to the compressor 12. Since the temperature of the refrigerant decreases as it passes through the expansion valve 14, the refrigerant before passing through the expansion valve 14 is hotter than the refrigerant that has passed through the expansion valve 14 and the evaporator 11. For this reason, the internal heat exchanger 34 can give the heat of the refrigerant sent from the radiator 13 to the expansion valve 14 to the refrigerant sent from the evaporator 11 to the compressor 12.

The heat pump 10 includes an HP-side control device 36 connected to the temperature sensor 35 in addition to a temperature sensor 35 (temperature sensor C) that measures the temperature of the outside air.
The HP-side control device 36 is, for example, a microcomputer. In addition to the temperature sensor 35, the temperature sensors 21, 22, 29, 31, 32, the expansion valve 14, the propeller fan 28, the compressor 12, the pressure switch 33, and the tank-side control. It is connected to the device 24. For this reason, the HP-side control device 36 and the tank-side control device 24 can communicate with each other, and the HP-side control device 36 acquires the measured temperature of the temperature sensor 22 and based on the acquired measured temperature of the temperature sensor 22. Then, the destination of the hot water sent from the lower part of the hot water storage tank 17 and passed through the radiator 13 is determined, and a command signal is transmitted to the three-way valve 19 via the tank side control device 24 as necessary.

When the compressor 12 and the circulation pump 18 are operated, the refrigerant in the refrigerant circulation circuit 15 starts to circulate. When water is sent out from the lower part of the hot water tank 17 to the hot water circulation circuit 16, the hot water in the hot water tank 17 is boiled up. Is done. At this time, the refrigerant circulating in the refrigerant circulation circuit 15 evaporates when passing through the evaporator 11, thereby reducing the surface temperature of the evaporator 11.
When the surface temperature of the evaporator 11 is lowered, frost is generated on the surface of the evaporator 11 depending on the outside air temperature and humidity, and the heat exchange efficiency between the refrigerant and the outside air in the evaporator 11 is lowered.

Therefore, when the HP-side control device 36 detects that frost has formed on the surface of the evaporator 11, it performs a defrosting operation to remove the frost and recovers the heat exchange efficiency of the evaporator 11. In the defrosting operation, as shown in FIG. 2, the compressor 12 operates to circulate the refrigerant in the refrigerant circulation circuit 15, and the circulation pump 18 operates at the minimum operation level. The expansion valve 14 is opened, that is, the refrigerant is not decompressed. By doing in this way, the refrigerant | coolant of 20-40 degreeC is discharged in gaseous form from the compressor 12, for example, this refrigerant | coolant reaches the evaporator 11 in a state with little temperature change, The temperature of the evaporator 11 surface is raised. The frost generated on the surface of the evaporator 11 becomes water due to the temperature rise on the surface of the evaporator 11 and flows out from a housing (not shown) housing the evaporator 11 and the like.
During the defrosting operation, the amount of water sent from the lower part of the hot water storage tank 17 to the hot water circulation circuit 16 is extremely small. Therefore, in FIG. Description is omitted.

The defrosting operation may be performed by another method, for example, by providing a bypass pipe that directly connects the refrigerant outlet side of the compressor and the refrigerant inlet side of the evaporator.
Specifically, when the defrosting operation is not performed, the closed bypass pipe is opened when the defrosting operation is performed, and the gaseous and high-temperature refrigerant discharged from the compressor is directly supplied to the evaporator. Thus, the frost generated on the surface of the evaporator is removed.

Does the HP-side control device 36 satisfy the condition 1 in which the determination target temperature obtained by subtracting the temperature measured by the temperature sensor 29 from the temperature measured by the temperature sensor 31 is less than or equal to a predetermined temperature ΔT1 and maintained for a predetermined time P? The integrated average value obtained by calculating the heating capacity of the hot water storage tank 17 by the radiator 13 every predetermined time Q (10 seconds in this embodiment) is continuously N times (in this embodiment, (3 times) When the reduced condition 2 is satisfied, it is determined that frost has occurred in the evaporator 11, and the defrosting operation is started. That is, when the condition 1 or the condition 2 is satisfied, the HP-side control device 36 determines that frost has formed on the surface of the evaporator 11.

Condition 1 is that when there is no frost on the surface of the evaporator 11, the refrigerant is completely vaporized and gasified when passing through the evaporator 11, whereas when there is frost on the surface of the evaporator 11, the heat of the evaporator 11 The exchange efficiency is lowered, and the refrigerant is focused on the point that it exits the evaporator 11 while being partially liquid.
While the refrigerant absorbs heat from the outside in the gas-liquid mixed state and evaporates, the temperature does not rise, and the temperature rises by absorbing heat from the outside in a state where evaporation is completed and all is in a gaseous state. To do.

For this reason, when there is no frost on the surface of the evaporator 11 and the refrigerant is in the form of a gas in the middle of passing through the evaporator 11, the temperature at which the refrigerant exits the evaporator 11 enters the evaporator 11. It becomes higher than the previous temperature. On the other hand, when there is frost on the surface of the evaporator 11 and the refrigerant exits the evaporator 11 in a gas-liquid mixed state, the temperature when the refrigerant exits the evaporator 11 is the temperature before entering the evaporator 11. Is equal to
Accordingly, when the refrigerant has frost on the surface of the evaporator 11, the temperature when the refrigerant exits the evaporator 11 is lower than when the surface of the evaporator 11 has no frost. Condition 1 uses this phenomenon to determine whether frost has formed on the surface of the evaporator 11.

Regardless of the presence or absence of frost on the surface of the evaporator 11, the temperature sensor 29 is disposed at a position where the refrigerant in the gas-liquid mixed state passes. In the present embodiment, the temperature sensor 29 is set to L with the length of the flow path through which the refrigerant in the evaporator 11 flows being L, the refrigerant inlet of the flow path being 0 position, and the refrigerant outlet of the flow path being L position. / 4 position to 3L / 4 position.

The temperature sensor 31 is provided at a position for measuring the temperature of the refrigerant that has passed through the internal heat exchanger 34. The refrigerant exiting the evaporator 11 absorbs heat from the refrigerant from the radiator 13 toward the expansion valve 14 while passing through the internal heat exchanger 34, and then the temperature is measured by the temperature sensor 31.
The refrigerant, which is all gaseous and exits the evaporator 11, rises in temperature when passing through the internal heat exchanger 34. Therefore, when the internal heat exchanger 34 is provided, the temperature measured by the temperature sensor 31 is higher than when the internal heat exchanger 34 is not provided.

On the other hand, the refrigerant exiting the evaporator 11 in the gas-liquid mixed state evaporates while passing through the internal heat exchanger 34. Therefore, even if it passes through the internal heat exchanger 34, if it is still in a gas-liquid mixed state, the measured temperatures of the temperature sensors 29 and 31 are equal, and all of them are gaseous while passing through the internal heat exchanger 34. If so, the measured temperature of the temperature sensor 31 becomes higher than the measured temperature of the temperature sensor 29.
And even if the refrigerant that exits the evaporator 11 in the gas-liquid mixed state becomes all gaseous while passing through the internal heat exchanger 34, the refrigerant is all gaseous and exits the evaporator 11. In comparison, the temperature measured by the temperature sensor 31 is lowered.

Therefore, regardless of the presence or absence of the internal heat exchanger 34, when the refrigerant is all in the gaseous state and exits the evaporator 11, the temperature sensor 31 is compared to when the refrigerant exits the evaporator 11 in a gas-liquid mixed state. The temperature obtained by subtracting the measured temperature of the temperature sensor 29 from the measured temperature, that is, the determination target temperature is increased.
Therefore, when the determination target temperature is maintained for a predetermined time P at a predetermined temperature ΔT1 or less, it can be determined that frost is generated on the surface of the evaporator 11.

The temperature ΔT1 is in the range of −2 ° C. or more and 2 ° C. or less, and in this embodiment, ΔT1 = 0 ° C. The reason why the temperature ΔT1 is not limited to 0 ° C. is that the pressure difference in the pipe between the measurement points of the temperature sensors 29 and 31 contributes, and frost forms on the surface of the evaporator 11 for each heat pump model. This is because the determination target temperature when it occurs is different. For this reason, it is necessary to determine the value of ΔT1 by experiments or the like for each heat pump model. The temperature lower than 0 ° C. can be set for ΔT1 because the pressure in the pipe at the position where the temperature sensor 31 is located near the compressor 12 and the temperature sensor 31 is attached is This is because the measured temperature of the temperature sensor 31 may be lower than the measured temperature of the temperature sensor 29 even if the refrigerant is all gaseous and exits the evaporator 11 below the pressure in the pipe.

The time P is not less than 10 seconds and not more than 60 seconds, and in the present embodiment, P = 30 seconds.
The reason why the time P is provided is that, even when no frost is generated on the surface of the evaporator 11, it is confirmed by experimental verification that the determination target temperature ≦ temperature ΔT1. While the defrosting operation is being performed, the hot water in the hot water storage tank 17 is not boiled, so it is preferable that the defrosting operation is not performed more than necessary. Therefore, this time P is provided in order to stably detect that frost is generated on the surface of the evaporator 11.

Moreover, since the fall of the heating capability of the radiator 13 also occurs due to factors other than the generation of frost on the surface of the evaporator 11, for example, a decrease in the outside air temperature, the surface of the evaporator 11 is satisfied only by satisfying the condition 1. It may be determined that frost is generated on the surface of the evaporator 11 when the following conditions 3 and 4 are satisfied simultaneously with the condition 1 without determining that the frost is generated.

Condition 3 is a condition in which the temperature obtained by subtracting the measured temperature of the temperature sensor 31 from the measured temperature (outside air temperature) of the temperature sensor 35 is maintained at a predetermined temperature ΔT2 or more for a predetermined time P. Condition 3 estimates the pressure in the pipe at the position where the temperature sensor 31 is attached based on the temperature of the temperature sensor 31, and based on the estimated pressure, there is no liquid in the refrigerant that has passed through the evaporator 11. This is a judgment.
When the refrigerant discharged from the evaporator 11 is in a gas-liquid mixed state, the pressure in the pipe at the position where the temperature sensor 31 is attached is lower than when the refrigerant discharged from the evaporator 11 is 100% gaseous. Since the pressure in the pipe at the position where the temperature sensor 31 is attached depends on the outside air temperature in addition to whether or not the refrigerant discharged from the evaporator 11 contains liquid, the measurement by the temperature sensor 35 is performed. Not only the temperature but also a value taking into account the temperature measured by the temperature sensor 31 is used as a criterion.

Condition 4 is a condition that the measured temperature of the temperature sensor 35 is maintained at a predetermined temperature T3 or lower for a predetermined time P. This is because frost does not occur when the outside air is higher than a predetermined temperature. It pays attention to.
If condition 3 is satisfied simultaneously with condition 1 without considering condition 4, it may be determined that frost has formed on the surface of the evaporator 11. Condition 3 is not considered without considering condition 3. At the same time, when the condition 4 is satisfied, it may be determined that frost is generated on the surface of the evaporator 11.
The temperature ΔT2 is in the range of 2 ° C. or higher and 13 ° C. or lower. In the present embodiment, ΔT2 = 7 ° C. The temperature T3 is in the range of 3 ° C. or higher and 7 ° C. or lower. In the present embodiment, T3 = 5 ° C. The temperature ΔT2 and the temperature T3 are determined by a test for each model of the heat pump.

Condition 2 is that when frost is generated on the surface of the evaporator 11, the heat exchange efficiency of the evaporator 11 is lowered and the water heating capacity of the hot water storage tank 17 by the radiator 13 (hereinafter also simply referred to as “heating ability”) is lowered. It is based on the idea of doing.
The heating capacity can be calculated by multiplying the value obtained by subtracting the measured temperature of the temperature sensor 21 from the measured temperature of the temperature sensor 22 by the output value of the circulation pump 18 and the coefficient. The heating capacity is calculated by the HP-side control device 36 (which may be the tank-side control device 24).

The HP-side control device 36 obtains the integrated average value of the heating capacities for all the heating capacities calculated so far and the newly calculated heating capacities at the timing when the heating capacities are newly calculated. Specifically, when the N + 1th heating capacity is newly calculated, the values of the N heating capacities calculated so far and the newly calculated heating capacities are added together, and the total value is calculated. By dividing by N + 1, the integrated average value of the heating capacity is derived.

Then, the HP-side control device 36 compares the newly derived integrated average value of the heating capacity with the previously calculated integrated average value of the heating capacity, and the integrated average value of the new heating capacity is the previous one. It is determined that frost has formed on the surface of the evaporator 11 when the heating capacity continues to be smaller than the integrated average value N times.
The reason why the cumulative average value of the new heating capacity is smaller than the cumulative average value of the previous heating capacity is not only once but continuously N times, because frost is generated on the surface of the evaporator 11. This is because the newly derived cumulative average value of the heating capacity may be smaller than the previously calculated cumulative average value of the heating capacity even when it is not.
Note that Q is not limited to 10 seconds, and Q can be set in the range of 5 seconds to 20 seconds. N is not limited to 3 times, and N is in the range of 2 to 5 times. The number of times can be set.

Conventionally, it has been determined that frost has occurred on the surface of the evaporator 11 only by satisfying the condition 2 without considering the condition 1, but frost is formed on the surface of the evaporator 11 even when the condition 2 is not satisfied. This has been confirmed by experimental verification. For example, this is a case where the frosting speed on the surface of the evaporator 11 is moderate.
For this reason, it is determined that frost has occurred in the evaporator 11 by satisfying the condition 1 or 2, and even if the condition 2 is not satisfied, it is determined that frost has been generated by satisfying the condition 1. I made it. By doing in this way, as a result, it was possible to shorten the time for the defrosting operation and shorten the time for boiling the hot water in the hot water storage tank 17 by the radiator 13. When the amount of frost generated in the evaporator 11 is small, the time for the defrosting operation is shortened.
Note that it is also possible to determine that frost has occurred in the evaporator 11 by satisfying the condition 3 and the condition 4 simultaneously with the condition 1 or by satisfying the condition 2.

Next, examples carried out for confirming the effects of the present invention will be described.
3 and 4 are graphs showing experimental results obtained by examining the time for the defrosting operation, and X1 in FIG. 3 and X2 in FIG. 4 indicate the time during which the defrosting operation was performed, respectively.
3 and 4, “estimated capacity” indicates a calculated value of the heating capacity of the radiator, and the value of “estimated capacity” rapidly decreases by starting the defrosting operation. Therefore, the defrosting operation is started at the timing when the value of the “estimated ability” suddenly decreases. Since “estimated ability” is described to indicate the start of the defrosting operation, FIG. 3 and FIG. 4 do not describe “estimated ability” after “estimated ability” suddenly decreases. Absent.

3 and 4, “intake” is the temperature measured by the temperature sensor that measures the temperature flowing into the compressor, and “heat exchange” is the temperature measured by the temperature sensor that measures the temperature of the refrigerant passing through the evaporator. It is.
The “superheat degree” corresponds to the determination target temperature, and is a value obtained by subtracting the “heat exchange” temperature from the “intake” temperature.

FIG. 3 shows that when the condition 2 is satisfied, it is determined that frost is generated on the surface of the evaporator, and the defrosting operation is started. The defrosting operation time X1 is 7 minutes. On the other hand, FIG. 4 determines that frost is generated on the surface of the evaporator when the condition 1 or 2 is satisfied, and starts the defrosting operation. The defrosting operation time X2 is 5 For minutes.
The defrosting operation is completed at the timing when the temperature of “heat exchange” rises to 2 ° C. in the experiment of FIG. 3 and the experiment of FIG. 4.

From this experimental result, when the criterion for determining that frost is generated on the surface of the evaporator is that the condition 1 or 2 is satisfied, the defrosting is performed rather than the case where only the condition 2 is satisfied. It was confirmed that driving can be shortened.
In addition, as a result of the experiment, in both cases of FIGS. 3 and 4, it was confirmed that frost was actually generated on the surface of the evaporator at the timing when it was determined that frost was generated on the surface of the evaporator. Has been.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and all changes in conditions and the like that do not depart from the gist are within the scope of the present invention.
For example, the heat pump may be used in an air temperature controller that adjusts the temperature in the room. In the case of an air temperature controller, the heating ability of the radiator is the ability to heat the room, the radiator is provided in the indoor unit, and the evaporator is provided in the outdoor unit.
Moreover, it is not necessary to provide an internal heat exchanger in the refrigerant circuit.
And only the condition 1 can be used as a criterion for determining that frost has occurred in the evaporator.

10: heat pump, 11: evaporator, 12: compressor, 13: radiator, 14: expansion valve, 15: refrigerant circulation circuit, 16: hot water circulation circuit, 17: hot water storage tank, 18: circulation pump, 19: three-way valve 20: Bypass pipe, 21-23: Temperature sensor, 24: Tank side control device, 25: Hot water supply pipe, 26: Water pipe, 28: Propeller fan, 29: Temperature sensor, 30: Accumulator, 31, 32: Temperature sensor 33: pressure switch, 34: internal heat exchanger, 35: temperature sensor, 36: HP side control device

Claims (4)

In a frosting determination method for a heat pump that detects the occurrence of frost in an evaporator that is arranged on the upstream side of the compressor along the flow of the refrigerant and takes heat from outside air to evaporate the liquid refrigerant,
The length of the flow path through which the refrigerant in the evaporator flows is L, the refrigerant inlet of the flow path is 0 position, the refrigerant outlet of the flow path is L position, and from the L / 4 position to 3L / 4 When the temperature obtained by subtracting the temperature of the refrigerant measured between the positions from the temperature of the refrigerant flowing into the compressor is maintained at a predetermined temperature ΔT1 or less for a predetermined time P, the evaporator It is determined that frost has occurred in the heat pump. In a frosting determination method for a heat pump that detects the occurrence of frost in an evaporator that is arranged on the upstream side of the compressor along the flow of the refrigerant and takes heat from outside air to evaporate the liquid refrigerant,
The length of the flow path through which the refrigerant in the evaporator flows is L, the refrigerant inlet of the flow path is 0 position, the refrigerant outlet of the flow path is L position, and from the L / 4 position to 3L / 4 The temperature obtained by subtracting the temperature of the refrigerant measured between the positions from the temperature of the refrigerant flowing into the compressor is equal to or lower than a predetermined temperature ΔT1, and the temperature of the refrigerant flowing into the compressor is When the temperature subtracted from the outside air temperature is equal to or higher than a predetermined temperature ΔT2 and the outside air temperature is equal to or lower than a predetermined temperature T3, the evaporator is maintained for a predetermined time P. It is determined that frost has occurred in the heat pump. A temperature sensor A for measuring the temperature of the refrigerant passing through the evaporator and a temperature sensor B for measuring the temperature of the refrigerant flowing into the compressor, and the heat absorbed by the evaporator from the outside air In heat pumps that dissipate heat and heat water or air,
The length of the flow path through which the refrigerant in the evaporator flows is L, the refrigerant inlet of the flow path is 0 position, the refrigerant outlet of the flow path is L position, and the temperature sensor A is L / It is arranged between the 4th position and the 3L / 4 position, and the temperature obtained by subtracting the measured temperature of the temperature sensor A from the measured temperature of the temperature sensor B is maintained for a predetermined time P at a predetermined temperature ΔT1 or less. And determining that frost has formed in the evaporator. A temperature sensor A for measuring the temperature of the refrigerant passing through the evaporator; a temperature sensor B for measuring the temperature of the refrigerant flowing into the compressor; and a temperature sensor C for measuring the temperature of the outside air. In a heat pump that heats water or air by radiating heat absorbed from outside air with a radiator,
The length of the flow path through which the refrigerant in the evaporator flows is L, the refrigerant inlet of the flow path is 0 position, the refrigerant outlet of the flow path is L position, and the temperature sensor A is L / It is arranged between the 4th position and the 3L / 4 position, the temperature obtained by subtracting the measured temperature of the temperature sensor A from the measured temperature of the temperature sensor B is equal to or lower than a predetermined temperature ΔT1, and the temperature sensor C The temperature obtained by subtracting the measured temperature of the temperature sensor B from the measured temperature is equal to or higher than a predetermined temperature ΔT2 and the measured temperature of the temperature sensor C is equal to or lower than a predetermined temperature T3. A heat pump characterized by determining that frost has formed in the evaporator when maintained for a period of time P.

Images