JPH08193740A - Defrosting control method for air source heat pump water chiller boiler - Google Patents

Abstract

PURPOSE: To plan more effective defrosting of an air side heat exchanger by controlling a solenoid valve provided on upper one of upper and lower air side heat exchangers defined by dividing an air side heat exchanger according to information from a pressure sensor while an air source heat pump water chiller boiler is being operated in a defrosting mode. CONSTITUTION: An air side heat exchanger 2 is divided into upper and lower portions and the upper portion is provided with a solenoid valve 9 and a check valve 10, and refrigerant flows through the solenoid valve 9 during defrosting cycle and flows through the check valve 10 during heating cycle. When a high-pressure pressure sensor 7 detects a first defrosting-completion judging value after defrosting operation is started, a controller 6 judges that frost on the air side heat exchanger 2 has been removed to a certain extent, frost still remains partially, portion where defrosting has been completed is of low thermal efficiency so that high-pressure pressure abruptly rises and the high pressure sensor 7 judges that defrosting-completion judging value has been detected. The controller 6 closes the solenoid valve 9 in order to stop allowing refrigerant gas to flow into upper side of the heat exchanger and make the refrigerant forcedly flow into lower side of the heat exchanger.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to defrost control of an air heat source heat pump chiller / heater, and more particularly to an air heat source heat pump chiller / heater having a large air side heat exchanger installed vertically.

[0002]

2. Description of the Related Art In the prior art, when the air-side heat exchanger is frosted, the heating cycle is switched to the cooling cycle and the high-temperature and high-pressure gas refrigerant discharged from the compressor is flowed to the air-side heat exchanger for defrosting. The control for returning to the original heating cycle (end of defrosting) is performed by using the pressure or time as the determination means. At this time, in order to improve the defrosting efficiency, there is also control including capacity control of the compressor. As a similar known example, there is JP-A-2-208436.

[0003]

The above-mentioned prior art is a method of defrosting by switching the heating cycle to the cooling cycle, but this method does not consider the structure of the air side heat exchanger. Generally, the air-side heat exchanger is composed of a plurality of heat transfer tubes and is usually installed vertically to the ground. That is, even if the heating cycle is switched to the cooling cycle (the air side heat exchanger is frosted and the heat exchange capacity is reduced, and the liquid refrigerant is staying in the heat exchanger), defrosting is performed. Since the heat exchanger is installed vertically, the high-temperature and high-pressure gas refrigerant discharged from the compressor does not try to flow evenly through the multiple heat transfer tubes due to the pressure difference with the liquid refrigerant, so that the resistance of the heat exchanger is low. Try to flow a lot to the upper side. Then, the air side heat exchanger is defrosted from the upper side, but it does not flow easily to the lower side, and the fan for the air side heat exchanger is stopped, so the heat exchange rate is poor at the part where defrosting is completed and the high pressure Rises, and there is a risk that defrosting will end even if there is insufficient defrosting. Also, in the case of a refrigeration cycle having a compressor with a capacity control mechanism, the capacity of the compressor is controlled in order to secure a sufficient defrosting time, but this method reduces the discharge amount of the compressor and the same problem as above. Occurs. In such a state, the frequency of switching the heating-defrosting operation increases, and even if the defrosting operation is performed, frost cannot be completely removed, resulting in extremely inefficient operation.

An object of the present invention is to provide a method for efficiently defrosting an air side heat exchanger.

[0005]

The air heat source heat pump chiller / heater of the present invention has the construction described in the claims.

[0006]

When the air-side heat exchanger is frosted and the heating operation is switched to the defrosting operation, the high-temperature and high-pressure refrigerant gas discharged from the compressor flows through the air-side heat exchanger to start defrosting. If a certain judgment value (for example, high pressure) is satisfied, it is determined that the upper side of the air side heat exchanger has completed defrosting, and the solenoid valve provided on the upper side of the air side heat exchanger, which is a feature of the present invention, is closed. The refrigerant flow path is shut off and forced to flow below the air side heat exchanger. By controlling in this way, high-temperature and high-pressure refrigerant gas circulates throughout the air-side heat exchanger, and efficient defrosting operation can be performed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a system diagram of a refrigeration cycle according to this embodiment. A refrigeration cycle is configured by the compressor 1, the air side heat exchanger 2, the expansion valve 3, the water side heat exchanger 4, the four-way valve 5, and the refrigerant pipe connecting them, and the controller 6 and the high pressure sensor. 7 is attached. The air side heat exchanger 2 exchanges heat with the air by blowing the air side heat exchanger fan 8. Further, the air-side heat exchanger 2 is divided into upper and lower two stages, which is a feature of the present invention, and an electromagnetic valve (normally "open") 9 and a check valve 10 are provided on the upper stage side for defrosting (cooling). The refrigerant flows through the solenoid valve 9 during the cycle and the check valve 10 during the heating cycle. The water-side heat exchanger 4 cools or heats the cold water or the hot water 11 by exchanging heat with the cold water or the hot water 11, and the cold water or the hot water 11 cools or heats another cooling or heating object. Used. In the cooling operation, this device uses the air-side heat exchanger 2 as a condenser and the water-side heat exchanger 4 as an evaporator to supply cold water to an object to be cooled. During heating operation, the air-side heat exchanger 2 is used as an evaporator by switching the four-way valve 5 from cooling operation.
Further, by using the water side heat exchanger 4 as a condenser, hot water is supplied to the object to be heated.

During the heating operation, since the air-side heat exchanger 2 is used as an evaporator as described above, the temperature of the air-side heat exchanger 2 becomes low and the moisture in the air is condensed and frosted on the air-side heat exchanger 2. Therefore, in order to remove the frost formed on the air-side heat exchanger 2, the four-way valve 5 is switched during the heating operation to temporarily perform the cooling operation, and the air-side heat exchanger fan 8 is stopped to defrost. . This defrosting operation ends when the pressure detected by the high pressure sensor 7 reaches the determination value. By the way, at the start of defrosting, the liquid refrigerant stays in the air-side heat exchanger 2, and the high-temperature and high-pressure gas refrigerant flows there. However, since the gas refrigerant tries to flow to the one with less resistance, the heat exchanger It does not try to flow evenly inside, but tries to flow more upward.
As a result, the defrosting efficiency is good in the upper part of the heat exchanger where a large amount of gas refrigerant flows, and the defrosting efficiency is poor in the lower part because the gas refrigerant does not flow easily. Further, since the air side heat exchanger fan 8 is stopped during the defrosting operation, the defrosting is completed and the heat exchange rate is poor in the portion.
The high-pressure pressure rapidly rises and the high-pressure sensor 7 determines that the pressure has reached the determination value even though there is a portion where frost is not completely removed, and the defrosting ends. In order to avoid this, the present invention controls as follows. That is, when the high pressure sensor 7 detects the first defrosting end determination value after the defrosting operation is started, the controller 6 can remove the frost on the air side heat exchanger 2 to some extent (the upper side of the heat exchanger is defrosted). However, there is still some frost (defrosting continues under the heat exchanger), and since the fan 8 for the air-side heat exchanger is stopped, the heat exchange rate in the part where defrosting is completed Poorly, the high pressure rises rapidly, and the high pressure sensor 7 determines that the defrosting end determination value is detected. Therefore, the controller 6 closes the solenoid valve 9 so that the gas refrigerant does not flow to the upper side of the heat exchanger (the defrosting completion section shuts off the gas refrigerant), and the lower side of the heat exchanger (incomplete defrosting) is forced. Allow the gas refrigerant to flow through the (part). In this way, the gas refrigerant flows in the entire area of the air-side heat exchanger 2, the high-pressure pressure rises again, and when the high-pressure sensor 7 detects the defrosting end determination value, the controller 6 controls the frost of the air-side heat exchanger 2. Is determined to be completely removed, the solenoid valve 9 is opened and the four-way valve 5 is switched to return to the original heating cycle. In this control, a pressure switch may be used instead of the high pressure sensor 7. A temperature sensor may be used instead of the high pressure sensor 7.

[0009]

According to the present invention, since the defrosting is efficiently performed by providing the solenoid valve on the upper side of the air side heat exchanger, frequent heating-defrosting cycle switching does not occur at the time of poor defrosting. As a result, the efficiency of heating operation can be improved and the reliability of refrigeration cycle components can be improved.

[Brief description of drawings]

FIG. 1 is a system diagram of a refrigeration cycle according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Air side heat exchanger, 3 ... Expansion valve, 4 ... Water side heat exchanger, 5 ... Four-way valve, 6 ... Controller, 7 ... High pressure sensor, 8 ... Air side heat exchanger fan , 9 ... Solenoid valve, 10
… Check valve, 11… Cold water or hot water.

Claims (1)

[Claims] 1. A pressure sensor and a controller are provided in a refrigeration cycle in which a compressor, an air-side heat exchanger, a pressure reducing device, a water-side heat exchanger, and an auxiliary device including a four-way valve are connected by a refrigerant pipe, and have a pressure sensor and a controller during heating operation. In an air heat source heat pump chiller / heater that performs reverse cycle defrosting, the air side heat exchanger is divided into upper and lower two stages, and an electromagnetic valve is provided in the upper stage air side heat exchanger to defrost the air heat source heat pump chiller / heater. A defrosting control method for an air-heat source heat pump chiller-heater, wherein the controller controls the solenoid valve based on information obtained from the pressure sensor to efficiently defrost.