CN115540361A - A method for defrosting control of low ambient temperature air source heat pump water heater - Google Patents

Abstract

The invention relates to the technical field of defrosting air source heat pump water heaters, and discloses a defrosting control method for air source heat pump water heaters with low ambient temperature, including a heating cycle and a refrigeration cycle. The defrosting control logic is relatively simple and convenient. Make the heat pump water heater defrost intelligently, defrost completely, no frost does not melt, and defrost in time when there is frost. The overall operation of the heat pump hot water is stable, and the temperature of the outlet water is kept within a reasonable range, which meets the requirements for hot water use. In particular, it provides logical support for the intelligent defrosting control system of heat pump water heaters.

Description

A method for defrosting control of low ambient temperature air source heat pump water heater

technical field

The invention relates to the technical field of defrosting of an air source heat pump water heater, in particular to a defrosting control method of a low ambient temperature air source heat pump water heater.

Background technique

Generally, the outdoor unit heat exchanger of the air source heat pump water heater is prone to frosting when heating in low temperature seasons. After frosting, the heat pump water heater needs to defrost itself, otherwise the frost on the surface of the outdoor unit heat exchanger will become thicker and thicker, which will affect heating. water. The principle of defrosting is that after the high-temperature refrigerant is discharged from the compressor and switched by the four-way reversing valve, the high-temperature refrigerant enters the outdoor heat exchanger for defrosting, that is, the high-temperature refrigerant is used for defrosting. Generally, the defrosting control of air source heat pump water heaters is relatively complicated, and the defrosting process is difficult to control, and even the frost does not melt for a long time, and the frost-free frequent defrosting phenomenon occurs. It has no obvious effect on defrosting control of heat pump water heaters.

Contents of the invention

The object of the present invention is to optimize the defrosting control of the air source heat pump water heater, so that the heat pump water heater can defrost intelligently, completely, without frost, and defrost in time when there is frost. Especially when the ambient temperature is low, the intelligent defrosting of the heat pump water heater makes the overall operation of the heat pump hot water stable, and the outlet water temperature is kept within a reasonable range, meeting the requirements for hot water use.

To achieve the above object, the present invention provides the following technical solutions:

A defrosting control method for a low ambient temperature air source heat pump water heater unit, including a heating cycle and a refrigeration cycle, the heating water cycle is as follows:

Hot water circulation, the air source heat pump water heater is at the outdoor heating working environment temperature, the outdoor unit low-temperature and low-pressure gas refrigerant is compressed into high-temperature and high-pressure refrigerant gas by the compressor, and the high-temperature and high-pressure refrigerant gas passes through several copper pipes and then passes through the four-way exchange After the valve (into the D pipe port and out of the E pipe port), it enters the casing heat exchanger to release heat and condense, and the high-pressure liquid refrigerant after condensing and heat release flows through the outdoor throttling electronic expansion valve to reduce the pressure to low temperature and low pressure Liquid refrigerant, the low-temperature and low-pressure liquid refrigerant after throttling absorbs heat in the outdoor fin heat exchanger. The low-temperature and low-pressure liquid refrigerant absorbs heat in the ambient air and evaporates into a low-temperature and low-pressure gas refrigerant. After the refrigerant passes through the four-way reversing valve (C pipe inlet, S pipe outlet), it is sucked and compressed by the compressor to realize a hot water cycle of an air heat pump hot water mechanism, and the four-way reversing valve D pipe enters and E pipe exits It is a channel, and the inlet of the C nozzle and the outlet of the S nozzle are a channel;

The defrost cycle is as follows:

Hot water circulation, the air source heat pump water heater is under the outdoor heating working environment temperature, the surface of the finned heat exchanger of the outdoor unit is frosted thickly, and the temperature difference between the refrigerant temperature sensor and the ambient temperature sensor of the heat exchanger coil, Judging the frosting situation, when the outdoor unit receives the defrosting command, the high-temperature and high-pressure refrigerant gas passes through the four-way reversing valve (into the D pipe port and out of the C pipe port), and enters the outdoor fin heat exchanger in the opposite direction to release heat Condensation (hot gas defrosting), after a certain defrosting time, exit defrosting according to the temperature difference between the heat exchanger coil refrigerant temperature sensor and the ambient temperature sensor, combined with the temperature rise value of the heat exchanger coil refrigerant temperature sensor, after condensing and exothermic The high-pressure liquid refrigerant flows through the outdoor throttling electronic expansion valve to reduce the pressure and become a low-temperature and low-pressure liquid refrigerant. The heat in the hot water in the appliance evaporates into a low-temperature and low-pressure gas refrigerant, and the low-temperature and low-pressure gas refrigerant passes through the four-way reversing valve (into the E pipe port and out of the S pipe port) and is sucked and compressed by the compressor to realize an air heat pump water heater In the reverse refrigeration cycle, the inlet of the D pipe and the outlet of the C pipe of the four-way reversing valve form a channel, and the entrance of the E pipe and the outlet of the S pipe form a channel.

Further, the control method of the defrosting cycle is as follows:

1. The low-temperature hot water machine enters the defrosting conditions in the heating mode:

1). Ambient temperature ≤ parameter H6, and heat exchanger coil refrigerant temperature ≤ parameter H2 for more than 3 minutes;

2). The cumulative running time of the compressor is ≥ parameter H1, and the continuous running time is ≥ 5 minutes;

3).(Ambient temperature - heat exchanger coil refrigerant temperature) ≥ set temperature difference (parameter H5), and last for more than 30 seconds;

During heating, when the above conditions are met at the same time, it will enter the defrosting operation;

2. Conditions for quitting defrosting:

When the heat exchanger coil refrigerant temperature > parameter H4 or the defrosting time reaches parameter H3, the system exits defrosting;

3. Defrost action;

1. When the defrosting entry conditions are met, the following actions will be taken:

(1) The compressor and fan stop running;

(2) Power on the four-way reversing valve at 30 seconds;

(3) The compressor starts at 60 seconds;

2. When the defrosting exit conditions are met, the following actions will be taken:

(1) The compressor stops running;

(2) The reversing valve of the four-way valve loses power at 55 seconds;

(3) Start the fan at 60 seconds, start the compressor after 5 seconds, and resume normal heating operation;

(4) The accumulated running time of the compressor is reset to zero, and the timer is restarted;

3. Abnormal end of defrosting:

(1) Shut down during defrosting, and the unit stops running immediately;

(2) When a failsafe shutdown occurs during defrosting, the system immediately exits defrosting and stops running;

(3) Low pressure protection is not detected during defrosting.

Compared with prior art, the beneficial effect of the present invention is:

In the present invention, the defrosting control logic is relatively simple and convenient, and the control enables the heat pump water heater to defrost intelligently, completely defrosting, no defrosting without defrosting, and defrosting in time when there is frost. The overall operation of the heat pump hot water is stable, and the temperature of the outlet water is kept within a reasonable range, which meets the requirements for hot water use. In particular, it provides logical support for the intelligent defrosting control system of heat pump water heaters.

1. Description of drawings

Fig. 1 is a structural schematic diagram of a defrosting control method for a low ambient temperature air source heat pump water heater unit according to the present invention;

Figure 2 is a schematic diagram of the defrosting cycle of the present invention.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

As shown in Figure 1, the air source heat pump water heater includes outdoor and side compressors (inlet and outlet), several copper pipes, four-way reversing valves (D port, C port, E port, S port), and casing type reversing valves. Heater, throttling electronic expansion valve, finned heat exchanger (including heat exchanger coil refrigerant temperature sensor), axial flow fan, external environment temperature sensor, gas-liquid separator, refrigerant and (inlet and outlet, outlet side), etc. .

The hot water cycle is as follows:

Hot water circulation, the air source heat pump water heater is at the outdoor heating working environment temperature, the low temperature and low pressure gas refrigerant of the outdoor unit is compressed into high temperature and high pressure refrigerant gas through the compressor, and the high temperature and high pressure refrigerant gas passes through the four-way reversing valve and enters Exothermic condensation in the double-pipe heat exchanger (and heat exchange using side water), the temperature of the water rises, ie hot water. After condensing and releasing heat, the high-pressure liquid refrigerant flows through the outdoor throttling electronic expansion valve to reduce the pressure and become a low-temperature and low-pressure liquid refrigerant. After throttling, the low-temperature and low-pressure liquid refrigerant absorbs heat in the outdoor fin heat exchanger (evaporator). The liquid refrigerant absorbs the heat in the ambient air and evaporates into a low-temperature and low-pressure gas refrigerant. The low-temperature and low-pressure gas refrigerant is sucked and compressed by the compressor to realize a hot water cycle of an air heat pump hot water mechanism.

In fact, when the outdoor ambient temperature is low and the outdoor humidity is high, the outdoor finned heat exchanger of the air source heat pump water heater is easy to frost when it is working in hot water, which affects the outdoor finned heat exchanger of the heat pump water heater. The heater evaporates and absorbs heat, which reduces the heating capacity at the end of the sleeve heat exchanger on the load side, thereby affecting the normal operation of the entire air source heat pump water heater. At this moment, it is necessary to defrost the outdoor fin heat exchanger in time.

According to the principle of refrigeration and the characteristics of the refrigerant, the defrosting of the existing air source heat pump water heater with the same configuration is not timely and incomplete, so that the air source heat pump water heater operates stably and reliably.

The defrost cycle is as follows:

Hot water circulation, the air source heat pump water heater is under the outdoor heating working environment temperature, the surface of the finned heat exchanger of the outdoor unit is frosted thickly, and the temperature difference between the refrigerant temperature sensor and the ambient temperature sensor of the heat exchanger coil, Judging the frosting situation, when the outdoor unit receives the defrosting command. After the high-temperature and high-pressure refrigerant gas passes through the four-way reversing valve (the direction of the four-way valve is switched by turning on and off the electromagnetic coil), it enters the outdoor fin heat exchanger in the opposite direction to release heat and condense (hot gas defrosting). After a certain amount of defrosting time, exit defrosting according to the temperature difference between the heat exchanger coil refrigerant temperature sensor and the ambient temperature sensor, combined with the temperature rise value of the heat exchanger coil refrigerant temperature sensor. After condensing and releasing heat, the high-pressure liquid refrigerant flows through the outdoor throttling electronic expansion valve to throttle and reduce pressure to become a low-temperature and low-pressure liquid refrigerant, and the throttled low-temperature and low-pressure liquid refrigerant absorbs heat in the casing heat exchanger heat), the low-temperature and low-pressure liquid refrigerant absorbs the heat in the hot water in the sleeve heat exchanger, and evaporates into a low-temperature and low-pressure gas refrigerant. The low-temperature and low-pressure gas refrigerant is sucked and compressed by the compressor to realize a reverse refrigeration cycle of the air heat pump water heater.

In fact, when the outdoor finned heat exchanger of the air source heat pump water heater is defrosting, the outdoor axial flow fan stops running, and the outdoor electronic expansion valve has a large opening, thereby quickly and completely defrosting.

As shown in Figure 1, the hot water cycle is as follows:

Hot water circulation, the air source heat pump water heater is at the outdoor heating working environment temperature, the outdoor unit low-temperature and low-pressure gas refrigerant is compressed into high-temperature and high-pressure refrigerant gas by the compressor, and the high-temperature and high-pressure refrigerant gas passes through several copper pipes and then passes through the four-way exchange After the valve (D pipe inlet, E pipe outlet), it enters the casing heat exchanger to release heat and condense (and use side water heat exchange), the temperature of the water rises, that is, hot water. After condensing and releasing heat, the high-pressure liquid refrigerant flows through the outdoor throttling electronic expansion valve to reduce the pressure and become a low-temperature and low-pressure liquid refrigerant. After throttling, the low-temperature and low-pressure liquid refrigerant absorbs heat in the outdoor fin heat exchanger (evaporator). The liquid refrigerant absorbs the heat in the ambient air and evaporates into a low-temperature and low-pressure gas refrigerant. Axial fan forced convection heat absorption. After the low-temperature and low-pressure gas refrigerant passes through the four-way reversing valve (C pipe inlet, S pipe outlet), it is sucked and compressed by the compressor to realize a hot water cycle of an air heat pump hot water mechanism. At this time, the inlet of the D pipe and the outlet of the E pipe of the four-way reversing valve are one channel, and the inlet of the C pipe and the outlet of the S pipe are one channel.

As shown in Figure 1, the defrost cycle is as follows:

Hot water circulation, the air source heat pump water heater is under the outdoor heating working environment temperature, the surface of the finned heat exchanger of the outdoor unit is frosted thickly, and the temperature difference between the refrigerant temperature sensor and the ambient temperature sensor of the heat exchanger coil, Judging the frosting situation, when the outdoor unit receives the defrosting command. After the high-temperature and high-pressure refrigerant gas passes through the four-way reversing valve (into the D pipe port and out of the C pipe port), it enters the outdoor fin heat exchanger in the reverse direction to release heat and condense (hot gas defrosting). After a certain amount of defrosting time, according to the temperature difference between the heat exchanger coil refrigerant temperature sensor and the ambient temperature sensor, the defrost will exit in combination with the temperature rise value of the heat exchanger coil refrigerant temperature sensor. After condensing and releasing heat, the high-pressure liquid refrigerant flows through the outdoor throttling electronic expansion valve to throttle and reduce pressure to become a low-temperature and low-pressure liquid refrigerant, and the throttled low-temperature and low-pressure liquid refrigerant absorbs heat in the casing heat exchanger heat), the low-temperature and low-pressure liquid refrigerant absorbs the heat in the hot water in the sleeve heat exchanger, and evaporates into a low-temperature and low-pressure gas refrigerant. The low-temperature and low-pressure gas refrigerant is sucked and compressed by the compressor after passing through the four-way reversing valve (into the E pipe and out of the S pipe), realizing a reverse refrigeration cycle of the air heat pump water heater. At this time, the entrance of the D pipe mouth and the exit of the C pipe mouth of the four-way reversing valve are one channel, and the entrance of the E pipe mouth and the exit of the S pipe mouth are one passage.

In fact, when the outdoor finned heat exchanger of the air source heat pump water heater is defrosting, the outdoor axial flow fan stops running, making the cooling temperature continue to rise, and the outdoor electronic expansion valve opens to the maximum, increasing the refrigerant flow rate, thereby quickly Defrost thoroughly.

As shown in Figure 2 and Table 1, the defrosting operation process control:

1. The low-temperature hot water machine enters the defrosting conditions in the heating mode:

1. Ambient temperature ≤ parameter H6, and heat exchanger coil refrigerant temperature ≤ parameter H2 for more than 3 minutes;

2. The cumulative running time of the compressor is ≥ parameter H1, and the continuous running time is ≥ 5 minutes;

3. (ambient temperature - heat exchanger coil refrigerant temperature) ≥ set temperature difference (parameter H5), and last for more than 30 seconds.

During heating, when the above conditions are met at the same time, it will enter the defrosting operation.

2. Conditions for quitting defrosting:

When the heat exchanger coil refrigerant temperature > parameter H4 or the defrosting time reaches parameter H3, the system exits defrosting;

3. Defrost action;

1. When the defrosting entry conditions are met, the following actions will be taken:

(1) The compressor and fan stop running;

(2) Power on the four-way reversing valve at 30 seconds;

(3) The compressor starts at 60 seconds;

2. When the defrosting exit conditions are met, the following actions will be taken:

(1) The compressor stops running;

(2) The reversing valve of the four-way valve loses power at 55 seconds;

(3) Start the fan at 60 seconds, start the compressor after 5 seconds, and resume normal heating operation;

(4) The cumulative running time of the compressor is reset to zero, and the timer is restarted.

3. Abnormal end of defrosting:

(1) Shut down during defrosting, and the unit stops running immediately;

(2) When a failsafe shutdown occurs during defrosting, the system immediately exits defrosting and stops running;

(3) Low pressure protection is not detected during defrosting.

The defrosting control logic of the present invention is relatively simple and convenient, and the control enables the heat pump hot water machine to defrost intelligently, completely defrosting, no defrosting without defrosting, and defrosting in time when there is frost. The overall operation of the heat pump hot water is stable, and the temperature of the outlet water is kept within a reasonable range, which meets the requirements for hot water use. In particular, it provides logical support for the intelligent defrosting control system of heat pump water heaters.

Table 1

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (2)

1. A method for defrosting control of a low ambient temperature air source heat pump water heater unit, characterized in that: it includes a heating cycle and a refrigeration cycle, and the heating water cycle is as follows: Hot water circulation, the air source heat pump water heater is at the outdoor heating working environment temperature, the outdoor unit low-temperature and low-pressure gas refrigerant is compressed into high-temperature and high-pressure refrigerant gas by the compressor, and the high-temperature and high-pressure refrigerant gas passes through several copper pipes and then passes through the four-way exchange After the valve (into the D pipe port and out of the E pipe port), it enters the casing heat exchanger to release heat and condense, and the high-pressure liquid refrigerant after condensing and heat release flows through the outdoor throttling electronic expansion valve to reduce the pressure to low temperature and low pressure Liquid refrigerant, the low-temperature and low-pressure liquid refrigerant after throttling absorbs heat in the outdoor fin heat exchanger. The low-temperature and low-pressure liquid refrigerant absorbs heat in the ambient air and evaporates into a low-temperature and low-pressure gas refrigerant. After the refrigerant passes through the four-way reversing valve (C pipe inlet, S pipe outlet), it is sucked and compressed by the compressor to realize a hot water cycle of an air heat pump hot water mechanism, and the four-way reversing valve D pipe enters and E pipe exits It is a channel, and the inlet of the C nozzle and the outlet of the S nozzle are a channel; The defrost cycle is as follows: Hot water circulation, the air source heat pump water heater is under the outdoor heating working environment temperature, the surface of the finned heat exchanger of the outdoor unit is frosted thickly, and the temperature difference between the refrigerant temperature sensor and the ambient temperature sensor of the heat exchanger coil, Judging the frosting situation, when the outdoor unit receives the defrosting command, the high-temperature and high-pressure refrigerant gas passes through the four-way reversing valve (into the D pipe port and out of the C pipe port), and enters the outdoor fin heat exchanger in the opposite direction to release heat Condensation (hot gas defrosting), after a certain defrosting time, exit defrosting according to the temperature difference between the heat exchanger coil refrigerant temperature sensor and the ambient temperature sensor, combined with the temperature rise value of the heat exchanger coil refrigerant temperature sensor, after condensing and exothermic The high-pressure liquid refrigerant flows through the outdoor throttling electronic expansion valve to reduce the pressure and become a low-temperature and low-pressure liquid refrigerant. The heat in the hot water in the appliance evaporates into a low-temperature and low-pressure gas refrigerant, and the low-temperature and low-pressure gas refrigerant passes through the four-way reversing valve (into the E pipe port and out of the S pipe port) and is sucked and compressed by the compressor to realize an air heat pump water heater In the reverse refrigeration cycle, the inlet of the D pipe and the outlet of the C pipe of the four-way reversing valve form a channel, and the entrance of the E pipe and the outlet of the S pipe form a channel. 2. The defrosting control method of a low ambient temperature air source heat pump water heater unit according to claim 1, characterized in that: The control method of the defrosting cycle is as follows: 1. The low-temperature hot water machine enters the defrosting conditions in the heating mode: 1). Ambient temperature ≤ parameter H6, and heat exchanger coil refrigerant temperature ≤ parameter H2 for more than 3 minutes; 2). The cumulative running time of the compressor is ≥ parameter H1, and the continuous running time is ≥ 5 minutes; 3).(Ambient temperature - heat exchanger coil refrigerant temperature) ≥ set temperature difference (parameter H5), and last for more than 30 seconds; During heating, when the above conditions are met at the same time, it will enter the defrosting operation; 2. Conditions for quitting defrosting: When the heat exchanger coil refrigerant temperature > parameter H4 or the defrosting time reaches parameter H3, the system exits defrosting; 3. Defrost action; 1. When the defrosting entry conditions are met, the following actions will be taken: (1) The compressor and fan stop running; (2) Power on the four-way reversing valve at 30 seconds; (3) The compressor starts at 60 seconds; 2. When the defrosting exit conditions are met, the following actions will be taken: (1) The compressor stops running; (2) The reversing valve of the four-way valve loses power at 55 seconds; (3) Start the fan at 60 seconds, start the compressor after 5 seconds, and resume normal heating operation; (4) The accumulated running time of the compressor is reset to zero, and the timer is restarted; 3. Abnormal end of defrosting: (1) Shut down during defrosting, and the unit stops running immediately; (2) When a failsafe shutdown occurs during defrosting, the system immediately exits defrosting and stops running; (3) Low pressure protection is not detected during defrosting.

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