JP2009174800A - Reheating dehumidifier and air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reheating dehumidifier or an air conditioner improving a capacity of defrosting, and capable of shortening a defrost time. <P>SOLUTION: An intake pressure sensor 28 and an intake temperature sensor 27 are provided in an intake side of a compressor 19, and a degree of intake superheat is calculated in a compressor intake side on receival of a pressure signal and a temperature signal from the intake pressure sensor 28 and the intake temperature sensor 27 during hot gas defrost operation. The reheating dehumidifier is equipped with a degree of superheat control means of carrying out opening adjustment of increasing an opening of an electric expansion valve 21 between a condenser 20 and an evaporator 22 when a calculated degree of intake superheat is a predetermined set value or more, and carrying opening adjustment of reducing the opening of the electric solenoid valve 21 when the calculated degree of intake superheat is less than the set value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a reheat dehumidifying device or an air conditioner, and relates to a technology for preventing a liquid back of a compressor during defrost operation and a technology for appropriately maintaining a refrigerant amount during defrost operation.

  In a refrigeration system using a refrigeration cycle, a reheat dehumidifier or an air conditioner, in defrost operation to melt frost formed on the evaporator, hot gas, which is high-pressure refrigerant discharged from the compressor, is allowed to flow to the evaporator. A hot gas defrost system is known that uses the heat to melt frost that forms on the evaporator.

  Conventionally, a main refrigerant circuit in which a compressor, a condenser, a temperature expansion valve, and an evaporator are connected in order, and a high-pressure gas pipe that connects the compressor and the condenser are branched from the middle, and a hot gas bypass solenoid valve There is known a refrigeration apparatus having a hot gas defrost bypass circuit connected to a low-pressure gas pipe connecting a temperature type expansion valve and an evaporator. This type of refrigeration apparatus further includes a condenser side blower for supplying outside air to the condenser, an evaporator side blower for supplying room air to the evaporator, an evaporator inlet temperature sensor and an intake temperature sensor, an evaporator inlet temperature sensor, An electromagnetic valve control device that receives a temperature signal from the suction temperature sensor and controls the hot gas bypass electromagnetic valve is provided. During the cooling operation, the refrigerant discharged from the compressor is condensed by exchanging heat with the outside air in the condenser, depressurized by the temperature type expansion valve, and evaporated by exchanging heat with the indoor air in the evaporator. Then, return to the compressor.

  In such a refrigeration apparatus, when the temperature of the indoor intake air decreases to about 15 ° C. or less, the surface temperature of the evaporator becomes 0 ° C. or less, and water vapor in the intake air becomes frost and becomes a fin of the evaporator. Frost on. When the amount of frost attached increases, the fins are clogged and the cooling capacity decreases.

  For this reason, conventionally, when the temperature signal from the evaporator inlet temperature sensor becomes, for example, a set temperature of −15 ° C. or less, an increase in frost is detected, the condenser-side fan and the evaporator-side fan are stopped, and the solenoid valve control device Open the hot gas bypass solenoid valve provided in the hot gas defrost bypass circuit, flow the refrigerant discharged from the compressor to the evaporator, and perform hot gas defrost operation to melt the frost generated in the evaporator there were.

  In that case, as the hot gas defrost operation proceeds, the compressor intake temperature rises, and the hot gas defrost operation is terminated by a temperature signal of 10 ° C., for example, when the intake temperature sensor determines that the frost has melted, and solenoid valve control is performed. The hot gas bypass solenoid valve is closed by the device, the condenser side blower and the evaporator side blower are operated, and the cooling operation is started again.

  Also, in other conventional refrigeration devices, a compressor, a condenser, a liquid reservoir, an expansion valve, and an evaporator are sequentially connected by a refrigerant pipe to form a main refrigerant circuit, and a compressor discharge pipe and an evaporator inlet There is a type in which a hot gas bypass circuit for connecting a pipe is provided, a three-way proportional valve is provided at a branch point, and a liquid line and a suction line are connected via an injection electromagnetic valve by an injection bypass circuit. In this configuration, during the defrost operation, when the refrigerant pressure value detected by the high pressure sensor HPT or the low pressure sensor LPT is lower than the lower set value, the injection solenoid valve is opened to replenish the suction line with the refrigerant pressure. When the value is higher than the upper set value, the opening of the three-way proportional valve is adjusted, the condenser fan is operated, the discharged gas refrigerant is released to the condenser of the main refrigerant circuit, and the refrigerant amount during defrost operation is adjusted. There are some (see, for example, Patent Document 1).

JP-A-6-347143

  In contrast to the refrigeration equipment described above, the reheat dehumidification equipment is provided with a condenser and an evaporator in the indoor unit, so the refrigerant pipe length is short and the required refrigerant amount does not fluctuate. In many cases, an accumulator is not provided. Thus, when adjusting the refrigerant amount during hot gas defrost operation, if the refrigerant pressure value detected by the high pressure sensor or the low pressure sensor is lower than the lower set value, the injection provided between the liquid line and the suction line When the solenoid valve is opened and the refrigerant is replenished to the suction line, the liquid refrigerant condensed in the condenser directly returns to the compressor suction side, so that a so-called liquid back is generated in which the damp refrigerant is sucked into the compressor. There was a problem.

  Further, in the conventional reheat dehumidifier, when the refrigerant pressure value detected in the refrigerant amount adjustment during the hot gas defrost operation is higher than the upper set value, only the condenser side blower is operated and the discharged refrigerant flows. The refrigerant amount in the hot gas defrost circuit is reduced by the reheat dehumidifying device provided with a condenser and an evaporator in the indoor unit and supplying air using the same blower. Since the above-mentioned control cannot be performed because the single operation cannot be performed, there is a problem that the high pressure cut causes an abnormal stop during the defrost operation.

  Further, in a conventional refrigeration apparatus in which a condenser and an evaporator are separately provided inside and outside the room, for example, when a condenser is provided on the outside of the room and the refrigerant is replenished in accordance with a decrease in the compressor suction pressure, The injection circuit is effective under high temperature conditions, but during defrost operation under low outside air conditions, the pressure on the condenser side or in the liquid reservoir becomes lower than the suction pressure, and refrigerant is introduced into the hot gas defrost circuit. There was a problem that it could not be returned.

The present invention has been made to solve the above-described problems, and the amount of refrigerant required for hot gas can be reduced according to the frosting state of the evaporator with a simple structure and irrespective of the intake air temperature and humidity. The present invention provides a reheat dehumidifying device or an air conditioner that improves the defrosting capability by supplying the defrosting circuit and shortens the defrosting time.
Moreover, the liquid back of the compressor at the time of a defrost operation can be avoided, and this provides the reheat dehumidification apparatus or air conditioning apparatus which does not require an accumulator.

A reheat dehumidifying apparatus according to the present invention branches from a main refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are connected in order, and a high-pressure gas pipe that connects the compressor and the condenser. A bypass circuit for hot gas defrost connected to a low-pressure gas pipe connecting the expansion valve and the evaporator via an on-off valve, taking in air from the outside and passing through the evaporator and the condenser In the reheat dehumidifier that sends it out again,
A suction pressure sensor and a suction temperature sensor are provided on the suction side of the compressor, and a pressure signal and a temperature signal are received from the suction pressure sensor and the suction temperature sensor during hot gas defrost operation, and suction on the compressor suction side is performed. The degree of superheat is calculated, and when the calculated suction superheat degree is equal to or larger than a predetermined set value, the opening degree adjustment is performed to increase the opening degree of the expansion valve, and when the calculated suction superheat degree is smaller than the set value, Intake superheat degree control means for adjusting the opening degree to reduce the opening degree of the expansion valve is provided.

The main refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are connected in series, and a high-pressure gas pipe that connects the compressor and the condenser are branched from the middle, and the expansion is performed through an on-off valve. A reheat dehumidifying device comprising a bypass circuit for hot gas defrost connected to a low-pressure gas pipe connecting a valve and the evaporator, and taking in air from the outside and sending it out again via the evaporator and the condenser In
An intake temperature sensor is provided on the intake side of the compressor, and an evaporator inlet temperature sensor is provided at the inlet of the evaporator, and temperature signals are received from the intake temperature sensor and the evaporator inlet temperature sensor during hot gas defrost operation. The suction superheat degree on the compressor suction side is calculated, and when the calculated suction superheat degree is equal to or larger than a predetermined set value, the opening adjustment is performed to increase the expansion valve, and the calculated suction superheat degree is set to the set value. When it is smaller than that, it is provided with suction superheat degree control means for adjusting the opening degree to reduce the opening degree of the expansion valve.

Further, the main refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are connected in order, and a high-pressure gas pipe that connects the compressor and the condenser are branched from the middle, and the expansion is performed through an on-off valve. A reheat dehumidifying device comprising a bypass circuit for hot gas defrost connected to a low-pressure gas pipe connecting a valve and the evaporator, and taking in air from the outside and sending it out again via the evaporator and the condenser In
A discharge pressure sensor and a discharge temperature sensor are provided on the discharge side of the compressor, and a pressure signal and a temperature signal are received from the discharge pressure sensor and the discharge temperature sensor during hot gas defrost operation, and a discharge is performed on the compressor discharge side. The degree of superheat is calculated, and when the calculated discharge superheat degree is equal to or larger than a predetermined set value, the opening degree adjustment is performed to increase the opening degree of the expansion valve, and when the calculated discharge superheat degree is smaller than the set value, Discharge superheat degree control means for adjusting the opening degree to reduce the opening degree of the expansion valve is provided.

The reheat dehumidifying apparatus of the present invention is configured to adjust the opening degree of the expansion valve based on the suction superheat degree or the discharge superheat degree calculated based on the pressure and temperature information obtained from the actual refrigerant circuit as described above. Thus, the following effects are produced.
While hot gas defrost is in progress, the amount of refrigerant required can be calculated by adjusting the amount of frost on the evaporator, regardless of the intake air conditions, and the amount of refrigerant can be adjusted. Can be shortened.
In addition, the liquid back to the compressor can be prevented, so that the reliability is improved and the installation of an accumulator becomes unnecessary.
Furthermore, by controlling the expansion valve before the amount of refrigerant in the hot gas defrost circuit becomes excessive, an unexpected high pressure cut during the defrost operation can be prevented.

Embodiment 1 FIG.
FIG. 1 is a refrigerant circuit and control system diagram of a reheat dehumidifier according to Embodiment 1 of the present invention. The reheat dehumidifying apparatus includes a compressor 19 that compresses and discharges the sucked refrigerant to a high pressure state, a condenser 20 that condenses and liquefies the discharged gas refrigerant discharged from the compressor 19, and an input electric signal. Accordingly, an expansion valve that can automatically adjust the opening degree of the orifice, for example, an electronic expansion valve 21, and an evaporator 22 for evaporating liquid refrigerant are connected in order.
Moreover, it has the air blower 24 which supplies wind to the condenser 20 and the evaporator 22. Further, the low-pressure gas pipe branches from the middle of the high-pressure gas pipe connecting the compressor 19 and the condenser 20 and connects the electronic expansion valve 21 and the evaporator 22 via the hot gas defrost electromagnetic valve 23 which is an on-off valve. A bypass circuit 23A for hot gas defrost connected to is provided.
Further, an evaporator inlet temperature sensor 26, a suction temperature sensor 27, and a suction pressure sensor (LPT) 28 are provided, and are connected to the evaporator inlet temperature sensor 26 and the suction temperature sensor 27, and hot gas is based on these signals. An electromagnetic valve control device 100 that controls the bypass electromagnetic valve 23 and the blower 24 is provided.

  In addition to these, from the suction superheat degree calculation unit 102 that calculates the suction superheat degree of the compressor 19 from the temperature signal of the suction temperature sensor 27 and the pressure signal of the suction pressure sensor (LPT) 28, and from the suction superheat degree calculation part 102 An expansion valve control device 101 that adjusts the opening degree of the electronic expansion valve 21 (the opening degree of the orifice of the electronic expansion valve 21) so that the suction superheat degree of the compressor 19 becomes a predetermined set value. Prepare. In FIG. 1, the expansion valve control device 101 and the suction superheat degree calculation unit 102 are collectively represented as suction superheat degree control means 110.

  Next, the operation of the reheat dehumidifier shown in FIG. 1 will be described. During the dehumidifying operation, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 19 is condensed in the condenser 20 and becomes a high-temperature and high-pressure liquid refrigerant. The heat released from the refrigerant at this time is used to warm the air sucked by the blower 24 when it passes between the fins applied to the condenser 20. Then, the high-temperature and high-pressure liquid refrigerant exiting the condenser 20 is decompressed by the electronic expansion valve 21 to become a room-temperature and low-pressure gas-liquid two-phase refrigerant.

  Since the reheat dehumidifier is provided with the condenser 20 and the evaporator 22 in the indoor unit, the accumulator is not provided for the purpose of relatively short piping length and small fluctuation of the necessary refrigerant amount and simplification of the refrigerant circuit. In many cases, during the dehumidifying operation, the opening degree of the electronic expansion valve 21 is controlled based on the degree of suction superheat for the purpose of preventing liquid back to the compressor 19. Here, in the electronic expansion valve 21, the suction superheat degree calculated based on the signals (information) of the suction pressure sensor (LPT) 28 and the suction temperature sensor 27 becomes a predetermined suction superheat degree (set value). The opening degree is adjusted.

  An evaporator 22 is provided downstream of the electronic expansion valve 21, and the normal-temperature and low-pressure gas-liquid two-phase refrigerant is vaporized here to become a normal-temperature and low-pressure gas refrigerant. At this time, since the refrigerant absorbs heat from the surroundings, the intake air sucked by the blower 24 is cooled and dehumidified when passing between the fins applied to the evaporator 22. The room-temperature and low-pressure gas refrigerant is sent to the compressor 19 to perform a recirculation operation where it is compressed again.

  As the air flow in the reheat dehumidifier, the intake air sucked by the blower 24 is cooled and dehumidified when it first passes between the fins applied to the evaporator 22, and then the fins applied to the condenser 20. When the air passes between the two, the air is warmed and supplied to the indoor space as air having a low relative humidity.

  In the reheat dehumidifying apparatus operating as described above, when the temperature of the intake air decreases to, for example, about 15 ° C. or less, the expansion valve controller 101 causes the electronic expansion valve to increase the suction superheat degree of the compressor 19. The opening degree is adjusted in a direction in which the opening degree of 21 is closed (a direction in which the opening degree is reduced). As a result, the surface temperature of the evaporator 22 becomes 0 ° C. or lower, and the water vapor in the intake air becomes frost and forms on the evaporator 22. As the amount of frost attached increases, the fins of the evaporator 22 are clogged, the evaporation capacity is lowered, and the suction superheat degree is further lowered. As the frosting progresses, the expansion valve control device 101 controls to further reduce the opening of the electronic expansion valve 21, and the suction pressure of the compressor 19 gradually decreases and the refrigerant circulation rate decreases, thereby cooling the refrigerant. The capacity decreases and the amount of dehumidification decreases.

  When it can be determined that the amount of frost formation in the evaporator 22 has increased by a predetermined amount or more, for example, when the evaporator inlet temperature sensor 26 detects a preset temperature, for example, −15 ° C. or less, the blower is operated by the solenoid valve control device 100. 24 is stopped, the hot gas bypass solenoid valve 23 is opened, and the hot gas defrost operation is started using the hot gas defrost bypass circuit 23A.

  At this time, the diameter of the hot gas bypass solenoid valve 23 is selected so as to avoid a high-pressure cut due to an increase in the discharge pressure of the compressor, and is set to be larger than the diameter of the orifice of the electronic expansion valve 21. The pressure loss is reduced, and the suction pressure of the compressor 19 increases with the start of defrosting. Since the suction pressure rises and the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 19 condenses by exchanging heat with the frost that forms on the evaporator 22, the suction superheat degree calculation unit 102 uses the suction temperature sensor. 27 and the suction superheat degree calculated from the suction pressure sensor (LPT) 28 are decreased. Then, when the calculated suction superheat degree is smaller than a predetermined set value, the opening adjustment for reducing the opening of the electronic expansion valve 21 is performed by the expansion valve control device 101.

  This control reduces the amount of refrigerant that merges with the high-temperature and high-pressure gas refrigerant that has passed through the hot gas bypass solenoid valve 23, that is, the amount of gas-liquid two-phase wet refrigerant that is condensed in the condenser 20 and passes through the electronic expansion valve 21. To do. For this reason, the compressor suction superheat degree increases, and the liquid back to the compressor 19 at the start of the defrost operation can be avoided.

  As the defrost operation proceeds, the frost around the fins of the evaporator 22 melts and the heat transfer rate decreases, and the suction superheat degree increases as the condensation capacity decreases. Therefore, the suction superheat degree calculated by the suction superheat degree calculation unit 102 increases. Then, when the calculated suction superheat degree is equal to or higher than a predetermined set value, the expansion valve control device 101 performs control to increase the opening degree of the electronic expansion valve 21 in accordance with the increase of the suction superheat degree. To do. Thereby, the refrigerant | coolant amount required according to the melting | fusing of the frost at the time of a defrost driving | operation can be supplied to the bypass circuit 23A for hot gas defrosts.

  Note that the suction superheat degree (the detection temperature of the suction temperature sensor−the saturation temperature of the detection pressure of the suction pressure sensor) determined as the set value of the suction superheat degree is, for example, 5 deg. Theoretically, it should be larger than 0 deg. However, it is preferably set to about 5 deg in consideration of sensor error and sensor time constant.

  As described above, it is possible to supply the optimum amount of refrigerant necessary for melting frost in the defrost operation, the defrost capacity increases with the increase of the refrigerant circulation amount, and the defrost operation time can be shortened. Further, even during the defrost operation, the opening degree of the electronic expansion valve 21 is adjusted based on the suction superheat degree, so that liquid back to the compressor 19 is avoided and the high pressure cut due to excessive refrigerant generated during the defrost operation is avoided. Abnormal stop can be prevented.

Since the necessary refrigerant amount during the defrost operation in the reheat dehumidifying device increases as the defrost operation proceeds, the control basically proceeds in the direction of increasing the opening degree of the electronic expansion valve 21 by the expansion valve control device 101.
Further, in order to avoid the problem that the hot gas bypass solenoid valve 23 has a small diameter, the discharge pressure rises due to the increase in the refrigerant amount under the control of the expansion valve control device 101, and abnormally stops due to a predetermined high pressure cut value. Do as follows. That is, the diameter of the hot gas bypass solenoid valve 23 is selected so that the discharge pressure is lower than the high pressure cut value at the proper refrigerant amount, that is, the set suction superheat degree, or the suction pressure sensor or the discharge pressure sensor of the compressor 19 is selected. By using either of them, the following upper limit set value is provided when adjusting the opening degree of the electronic expansion valve 21.
For example, in the R410A refrigerant model, when the high pressure cut value is 4.15 MPa, when the compressor discharge pressure of 3.0 MPa or more is detected, control is performed to close the opening of the electronic expansion valve 21 (opening is set to 0). . Further, in the R410A refrigerant model, when the high pressure cut value is 4.15 MPa, when the compressor suction pressure of 1.0 MPa or more is detected, control is performed to close the opening of the electronic expansion valve 21 (the opening is set to 0). . The set value of the discharge pressure or the suction pressure is determined so that a high pressure cut is not applied due to a high pressure fluctuation during the defrost operation and when switching from the defrost operation to the dehumidification operation.
By such control, it is possible to avoid an abnormal stop due to a high-pressure cut during an unexpected defrost operation and an abnormal stop due to a high-pressure cut due to a pressure fluctuation generated when the defrost operation is switched to the dehumidifying operation. This control can also be applied to each embodiment described later.

  As the defrosting operation proceeds, the suction temperature of the compressor 19 rises, and upon receiving a compressor suction temperature at which it can be determined that the frost has melted, for example, a temperature signal of the suction temperature sensor 27 of 10 ° C., the solenoid valve control device 100 causes the hot gas. The bypass solenoid valve 23 is closed, the blower 24 is operated, and the dehumidifying operation is resumed.

Instead of using the signal of the suction pressure sensor (LPT) 28, control using the temperature signal of the inlet temperature sensor 26 of the evaporator 22 is also possible. That is, the degree of suction superheat is calculated in consideration of the pressure loss in the evaporator 22, and the degree of opening adjustment for increasing the degree of opening of the electronic expansion valve 21 when the calculated degree of suction superheat is equal to or greater than a preset value. When the calculated suction superheat degree is smaller than the set value, a suction superheat degree control means for adjusting the opening degree to reduce the opening degree of the electronic expansion valve 21 may be provided.
In this case, the suction superheat degree (detection temperature of the suction temperature sensor−detection temperature of the evaporator inlet temperature sensor) determined as the set value of the suction superheat degree is, for example, 2 deg.
According to this control, the opening degree control of the hot gas bypass electromagnetic valve 23 can also be performed based on the evaporator inlet temperature sensor 26, so that the suction pressure sensor (LPT) 28 is not required, and the cost can be reduced. .

Embodiment 2. FIG.
In the first embodiment, the opening degree of the electronic expansion valve 21 is adjusted according to the intake superheat degree. However, in the second embodiment, the opening degree of the electronic expansion valve 21 is reduced particularly immediately after the start of defrosting. The degree of opening is adjusted (including the case where the degree of opening is 0), and the degree of opening of the electronic expansion valve 21 is increased in accordance with the increase in the degree of suction superheat detected thereafter. Hereinafter, the second embodiment will be described with reference to FIG.

  When the opening degree of the electronic expansion valve 21 is open during the hot gas defrosting operation, the refrigerant that has exchanged heat and becomes liquid in the condenser 20 passes through the electronic expansion valve 21 and becomes a gas-liquid two-phase wet refrigerant. The frost that is discharged from the compressor 19 and enters the evaporator 22 by merging with the high-temperature and high-pressure gaseous refrigerant that has passed through the hot gas defrost bypass circuit 23A and frosted on the evaporator 22 By exchanging heat with the refrigerant, the refrigerant is further moistened and sucked into the compressor 19. For this reason, there is a problem that a so-called liquid back is generated in which the damp refrigerant is sucked into the compressor 19.

Further, during the hot gas defrost operation, the opening degree of the electronic expansion valve 21 is adjusted by the suction superheat degree calculation unit 102 using the temperature signal of the suction temperature sensor 27 and the pressure signal of the suction pressure sensor (LPT) 28 or the evaporator inlet temperature sensor. 26, the intake superheat degree is calculated based on them, and the opening degree is adjusted by the expansion valve control device 101 based on the calculated intake superheat degree.
For this reason, at the time of a sudden load change at the start of defrost, the detection of the temperature sensing cylinder portion of the intake temperature sensor 27 cannot be followed, and the opening degree adjustment by the expansion valve control device 101 is performed immediately after the start of defrost. There is a problem that liquid back occurs until it follows.

  Therefore, in the expansion valve control apparatus 101, the time until the opening adjustment of the electronic expansion valve 21 by the expansion valve control apparatus 101 can be followed immediately after the start of the defrost operation is made to reduce the opening of the electronic expansion valve 21. Adjust to. For example, the opening degree of the electronic expansion valve 21 is set to zero. Thereafter, the suction superheat degree increases as the frost frosted on the evaporator 22 melts. When the suction superheat degree increases and becomes equal to or greater than a predetermined set value (same as the set value of each suction superheat degree described in the first embodiment), electronic expansion is performed according to the increase of the suction superheat degree. Control is performed so as to increase the opening of the valve 21. Thereby, it is possible to avoid the liquid back to the compressor 19 at the start of the defrost operation. Further, by adjusting the electronic expansion valve 21 in accordance with the change in the degree of suction superheat, the amount of refrigerant corresponding to the frost melting during the defrost operation can be supplied to the defrost circuit. This makes it possible to supply the optimum amount of refrigerant according to the frost melting in the defrost operation, increase the refrigerant circulation amount, improve the defrost capability, and shorten the defrost operation time.

  In the flow of air in the reheat dehumidifier, the intake air sucked by the blower 24 first passes through the evaporator 22 and then passes through the condenser 20. For this reason, fluctuations that occur in refrigeration equipment each provided with a condenser and an evaporator, for example, indoors and outdoors, such as a condenser outside the room, the high pressure decreases when the outside air is low, and the high pressure increases when the outside air temperature is high. Such fluctuations do not occur in the reheat dehumidifier. Further, as the amount of frost increases, the evaporation capacity decreases and the suction superheat degree decreases. Therefore, the electronic expansion valve 21 is controlled for the purpose of increasing the suction superheat degree by the electronic expansion valve control based on the suction superheat degree during the dehumidifying operation. Control for reducing the opening degree is activated, and then the solenoid valve control device 100 switches to hot gas defrost operation when the evaporator inlet temperature reaches a preset value.

  As a result, the suction pressure and discharge pressure at the start of hot gas defrost operation are almost constant regardless of the intake air temperature and humidity, and the refrigerant distribution in the refrigerant circuit at the start of hot gas defrost is also almost constant regardless of the outdoor temperature and humidity. Conceivable. Therefore, during the defrost that occurs in the conventional refrigeration system under the condition that the outside air temperature is low, the pressure on the condenser side or in the liquid reservoir becomes lower than the suction pressure, and the refrigerant is returned to the hot gas defrost circuit. The problem of not being able to be solved.

Embodiment 3 FIG.
In the first or second embodiment, the opening degree of the electronic expansion valve 21 is adjusted using the suction superheat degree of the compressor 19, but in the third embodiment, the discharge superheat degree of the compressor 19 is adjusted. Is used to adjust the opening of the electronic expansion valve.
FIG. 2 is a refrigerant circuit and control system diagram of the reheat dehumidifier according to Embodiment 3 of the present invention. The same reference numerals as those in FIG. 1 denote the same or equivalent parts as described in FIG. In FIG. 2, a discharge temperature sensor 25 and a discharge pressure sensor (HPT) 29 are provided. The discharge superheat degree calculation unit 103 that calculates the discharge superheat degree of the compressor 19 from the temperature signal of the discharge temperature sensor 25 and the pressure signal of the discharge pressure sensor (HPT) 29, and the discharge from the discharge superheat degree calculation part 103 An expansion valve control device 101 that adjusts the opening degree of the electronic expansion valve 21 so as to receive the degree of superheat and to set the discharge superheat degree of the compressor 19 to a predetermined set value. The expansion valve control device 101 and the discharge superheat degree calculation unit 103 are collectively represented as discharge superheat degree control means 111.

In the compressor having no problem in quality as long as the operation is performed with a discharge superheat degree equal to or higher than a certain value with respect to the liquid back, the opening degree of the electronic expansion valve 21 can be adjusted according to the discharge superheat degree.
Similarly to the hot gas defrost operation described above, when it can be determined that the amount of frost formation in the evaporator 22 has increased, for example, when the evaporator inlet temperature sensor 26 detects a preset temperature, for example, −15 ° C. or less, the solenoid valve While the blower 24 is stopped by the control device 100, the hot gas bypass solenoid valve 23 is opened. As a result, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 19 enters the evaporator 22 via the hot gas defrost bypass circuit 23A, and is condensed by exchanging heat with the frost formed on the evaporator 22, It is sucked into the compressor 19 as a liquid / gas two-phase refrigerant. Accordingly, the discharge superheat degree calculated by the discharge pressure sensor (HPT) 29 and the discharge temperature sensor 25 in the discharge superheat degree calculation unit 103 decreases. When the calculated discharge superheat degree is smaller than a predetermined set value, the expansion valve control device 101 performs control so as to reduce the opening degree of the electronic expansion valve 21. With this control, a decrease in the degree of superheat discharged from the compressor is avoided, and a failure due to liquid back to the compressor 19 can be avoided.

  As the defrosting operation proceeds, the heat exchange in the evaporator 22 decreases, so the discharge superheat degree calculated by the discharge superheat degree calculation unit 103 increases. Then, when the calculated discharge superheat degree is equal to or greater than a predetermined set value, the frost during the defrost operation is controlled by increasing the opening degree of the electronic expansion valve 21 in accordance with the increase in the discharge superheat degree. The amount of refrigerant corresponding to the melting of can be supplied to the defrost circuit. This makes it possible to supply an optimum amount of refrigerant according to the frost melting in the defrost operation, increase the defrost capability, and shorten the defrost operation time. Further, by controlling by the degree of discharge superheat, liquid back to the compressor 19 is avoided and reliability is improved.

  The discharge superheat degree determined as the set value of the discharge superheat degree (the detection temperature of the discharge temperature sensor−the saturation temperature of the detection pressure of the discharge pressure sensor) is determined in consideration of the liquid back durability performance of the compressor. And

  Note that control according to the second embodiment may be performed. That is, when the hot gas defrosting operation is started, the opening degree of the electronic expansion valve 21 is reduced or adjusted to 0, and then the discharge superheat degree is calculated. As the calculated discharge superheat degree becomes larger than the set value, The opening degree of the electronic expansion valve 21 may be increased.

Embodiment 4 FIG.
In the first to third embodiments, it has been described that the opening degree of the electronic expansion valve 21 is adjusted according to the suction superheat degree and the discharge superheat degree of the compressor 19, but in the fourth embodiment, particularly immediately after the start of defrosting. An aspect in which the electronic expansion valve 21 is adjusted to be closed and the opening degree of the electronic expansion valve is adjusted in accordance with the suction pressure or discharge pressure of the compressor detected after a predetermined time has elapsed will be described.

3 is a refrigerant circuit and control system diagram of a reheat dehumidifier having a discharge pressure control means 112 for controlling the electronic expansion valve 21 based on the discharge pressure of the compressor 19, and FIG. It is a refrigerant circuit of a reheating dehumidifier provided with the suction pressure control means 113 which controls the electronic expansion valve 21 based on this, and a control system diagram. 3 and 4, the same reference numerals as those in FIGS. 1 and 2 represent the same or equivalent components shown in those drawings.
In FIG. 3, the expansion valve control device 101 and the discharge pressure comparison unit 104 are collectively represented as the discharge pressure control means 112, and in FIG. 4, the expansion valve control device 101 and the suction pressure comparison unit 105 are inhaled. The pressure control means 113 is collectively shown.

As for the air flow in the reheat dehumidifier, the intake air sucked by the blower 24 first passes through the evaporator 22 and then passes through the condenser 20. For this reason, the high pressure decreases when the outside air is low and the outside air is low, such as a refrigeration device provided with a condenser, an evaporator, and a blower inside and outside the room, and the high pressure increases when the outside air temperature is high. There are no fluctuations.
Further, as the amount of frost increases, the evaporation capability decreases and the suction superheat degree decreases. Therefore, the electronic expansion valve 21 is controlled for the purpose of increasing the suction superheat degree by controlling the electronic expansion valve 21 according to the suction superheat degree during the dehumidifying operation. Control to close the opening of 21 works.

  Thus, when it can be determined that the amount of frost formation on the evaporator 22 has increased, for example, when the temperature signal from the evaporator inlet temperature sensor 26 becomes, for example, −15 ° C. or lower, which is the set temperature, the compressor discharge pressure and compression The machine intake pressure is not significantly different depending on the intake air temperature and humidity. Therefore, it can be said that the refrigerant amount in the hot gas defrost bypass circuit 23A at the start of the hot gas defrost is not significantly different.

  When a preset temperature of the evaporator inlet temperature, for example, a set temperature of −15 ° C. or lower, is detected by the temperature signal from the evaporator inlet temperature sensor 26, the solenoid valve controller 100 opens the hot gas defrost solenoid valve 23, The blower 24 stops. As a result, the high-temperature and high-pressure gas refrigerant discharged from the compressor 19 flows into the evaporator 22 via the hot gas defrost bypass circuit 23 </ b> A and melts the frost generated in the evaporator 22. At the start of defrosting, the frost formed on the evaporator 22 is fixed and the heat transfer rate is high, and the heat transfer rate decreases as the frost melts. Until the frost has melted, the operation is performed at a substantially constant suction superheat.

  As a result, during the time (predetermined time) during which the suction superheat degree rises to a predetermined set value, the opening degree of the electronic expansion valve 21 is reduced or controlled to zero. Then, after the suction superheat degree becomes equal to or higher than the set value, the compressors in the respective comparison units 104 or 105 are set so that the suction pressure or discharge pressure is set in advance so that no liquid back is generated in the compressor 19. The opening adjustment of the electronic expansion valve 21 is increased by the expansion valve control device 101 while comparing the suction pressure or discharge pressure of 19 with the corresponding set value.

Specifically, after the start of the defrost operation, the opening time of the electronic expansion valve 21 is reduced (for example, opened) for a time (for example, 30 seconds after the start of the defrost operation) until the target intake superheat degree (for example, 5 deg) is increased. 0 degree). Thereafter, a pressure value (for example, suction) set in advance so that the suction superheat degree or the discharge superheat degree of the compressor 19 becomes equal to or higher than a predetermined set value (for example, suction superheat degree 5 deg or discharge superheat degree 25 deg) through the defrost operation. The opening degree of the electronic expansion valve 21 is increased until the pressure reaches 0.5 Mpa or the discharge pressure 1.5 Mpa), and the opening degree of the electronic expansion valve 21 is decreased (for example, the opening degree is set to 0) above the set pressure value.
Thereby, the liquid back | bag at the time of a defrost start can be avoided, and the refrigerant | coolant shortage during a defrost driving | operation can be avoided.

Embodiment 5 FIG.
The first embodiment also applies to an air conditioner to which a refrigeration cycle similar to the reheat dehumidifier shown in FIGS. 1 to 4 is applied, particularly an air conditioner in which an evaporator and a condenser are placed in the same air temperature and humidity space. It is possible to control an expansion valve (such as an electronic expansion valve that can be automatically controlled) as shown in FIGS. The air conditioner configured as described above is capable of supplying a necessary amount of refrigerant according to the frost melting state of the evaporator while hot gas defrost is in progress, and has the effect of shortening the defrost time, and also provides liquid back. It is possible to prevent this, and the reliability is improved, and the cost can be improved by eliminating the accumulator.

As described above, in the reheat dehumidifying apparatus and the air conditioner according to the embodiment of the present invention, the opening degree of the electronic expansion valve is adjusted by the suction superheat degree, the discharge superheat degree, the suction pressure or the discharge pressure during the hot gas defrost operation. And a control means for adjusting the refrigerant amount by calculating the necessary refrigerant amount according to the frost melting state of the evaporator during the hot gas defrosting process. The ability is improved and the defrosting operation time can be shortened.
Further, by providing a control means for calculating the necessary refrigerant amount and adjusting the refrigerant amount, there is an effect of preventing an abnormal stop due to a high-pressure cut that occurs during the defrost operation.
Further, since the opening of the electronic expansion valve is adjusted so as to prevent liquid back to the compressor, the reliability is improved, the accumulator can be eliminated, and the cost can be reduced.

  The suction superheat degree control means, the discharge superheat degree control means, the suction pressure control means and the discharge pressure control means described in the above embodiments are obtained from a microcomputer or various devices programmed with the predetermined control operation as described above. Can be configured.

The refrigerant circuit figure and control system diagram of the reheat dehumidification apparatus which concern on Embodiment 1,2. The refrigerant circuit diagram and control system diagram of the reheat dehumidifier according to Embodiment 3. The refrigerant circuit diagram and control system diagram of the reheat dehumidifying apparatus according to Embodiment 4. The refrigerant circuit diagram and control system diagram of another reheat dehumidification apparatus which concerns on Embodiment 4. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 19 Compressor, 20 Condenser, 21 Electronic expansion valve, 22 Evaporator, 23 Hot gas bypass solenoid valve, 23A Hot gas defrost bypass circuit, 24 Blower, 25 Discharge temperature sensor, 26 Evaporator inlet temperature sensor, 27 Inhalation Temperature sensor, 28 Suction pressure sensor (LPT), 29 Discharge pressure sensor (HPT), 100 Solenoid valve control device, 101 Expansion valve control device, 102 Suction superheat degree calculation unit, 103 Discharge superheat degree calculation unit, 104 Discharge pressure comparison unit 105, suction pressure comparison unit, 110 suction superheat degree control means, 111 discharge superheat degree control means, 112 discharge pressure control means, 113 suction pressure control means.

Claims (16)

A main refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected;
A hot gas defrost bypass circuit that branches from the middle of a high-pressure gas pipe connecting the compressor and the condenser and connected to a low-pressure gas pipe connecting the expansion valve and the evaporator via an on-off valve; ,
In the reheat dehumidification device that takes in air from the outside and sends it out again via the evaporator and the condenser,
A suction pressure sensor and a suction temperature sensor are provided on the suction side of the compressor;
During the hot gas defrost operation, a pressure signal and a temperature signal are received from the suction pressure sensor and the suction temperature sensor to calculate a suction superheat degree on the compressor suction side, and the calculated suction superheat degree is equal to or greater than a predetermined set value. In this case, the opening degree adjustment is performed to increase the opening degree of the expansion valve. When the calculated suction superheat degree is smaller than the set value, the suction superheat degree control is performed to adjust the opening degree to reduce the opening degree of the expansion valve. A reheat dehumidifying device comprising means. A main refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected;
A hot gas defrost bypass circuit that branches from the middle of a high-pressure gas pipe connecting the compressor and the condenser and connected to a low-pressure gas pipe connecting the expansion valve and the evaporator via an on-off valve; ,
In the reheat dehumidification device that takes in air from the outside and sends it out again via the evaporator and the condenser,
An intake temperature sensor is provided on the intake side of the compressor, and an evaporator inlet temperature sensor is provided at the inlet of the evaporator.
During the hot gas defrost operation, a temperature signal is received from the suction temperature sensor and the evaporator inlet temperature sensor to calculate a suction superheat degree on the compressor suction side, and the calculated suction superheat degree is equal to or higher than a predetermined set value. When the calculated intake superheat degree is smaller than the set value, the intake superheat degree control means adjusts the opening degree to reduce the opening degree of the expansion valve. A reheat dehumidifying device comprising: A main refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected;
A hot gas defrost bypass circuit that branches from the middle of a high-pressure gas pipe connecting the compressor and the condenser and connected to a low-pressure gas pipe connecting the expansion valve and the evaporator via an on-off valve; ,
In the reheat dehumidification device that takes in air from the outside and sends it out again via the evaporator and the condenser,
A discharge pressure sensor and a discharge temperature sensor are provided on the discharge side of the compressor,
During the hot gas defrost operation, a pressure signal and a temperature signal are received from the discharge pressure sensor and the discharge temperature sensor to calculate a discharge superheat degree on the compressor discharge side, and the calculated discharge superheat degree is equal to or greater than a predetermined set value. Discharge superheat degree control that adjusts the opening degree to increase the opening degree of the expansion valve, and adjusts the opening degree to reduce the opening degree of the expansion valve when the calculated discharge superheat degree is smaller than the set value A reheat dehumidifying device comprising means.   The suction superheat degree control means adjusts the opening degree to reduce the opening degree of the expansion valve at the start of hot gas defrost operation, and then receives a pressure signal and a temperature signal from the suction pressure sensor and the suction temperature sensor to receive the suction signal. The reheat dehumidifying device according to claim 1, wherein the degree of superheat is calculated, and the opening degree of the expansion valve is increased as the calculated suction superheat degree becomes larger than the set value.   The suction superheat degree control means adjusts the opening degree to reduce the opening degree of the expansion valve with the start of hot gas defrost operation, and then receives temperature signals from the suction temperature sensor and the evaporator inlet temperature sensor to receive the suction superheat. The reheat dehumidifying device according to claim 2, wherein the degree of opening is adjusted so that the degree of opening of the expansion valve is increased as the calculated suction superheat degree becomes larger than the set value.   The discharge superheat degree control means adjusts the opening degree to reduce the opening degree of the expansion valve at the start of hot gas defrost operation, and then receives a pressure signal and a temperature signal from the discharge pressure sensor and the discharge temperature sensor, and then discharges the discharge valve. The reheat dehumidifying device according to claim 3, wherein the degree of superheat is calculated, and the degree of opening is adjusted to increase the degree of opening of the expansion valve as the calculated discharge superheat degree becomes larger than the set value. A main refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected;
A hot gas defrost bypass circuit that branches from the middle of a high-pressure gas pipe connecting the compressor and the condenser and connected to a low-pressure gas pipe connecting the expansion valve and the evaporator via an on-off valve; ,
In the reheat dehumidification device that takes in air from the outside and sends it out again via the evaporator and the condenser,
When the hot gas defrost operation is started, the opening of the expansion valve is adjusted so that the opening of the expansion valve is reduced. After a predetermined time has elapsed, a pressure signal is received from a discharge pressure sensor provided on the discharge side of the compressor, A reheat dehumidifying device comprising discharge pressure control means for adjusting the opening of the expansion valve until a set value is reached. A main refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected;
A hot gas defrost bypass circuit that branches from the middle of a high-pressure gas pipe connecting the compressor and the condenser and connected to a low-pressure gas pipe connecting the expansion valve and the evaporator via an on-off valve; ,
In the reheat dehumidification device that takes in air from the outside and sends it out again via the evaporator and the condenser,
When the hot gas defrosting operation is started, the opening of the expansion valve is adjusted to be small, and after a predetermined time has passed, a pressure signal is received from a suction pressure sensor provided on the suction side of the compressor, and the compressor suction pressure is set in advance. A reheat dehumidifying device, comprising suction pressure control means for adjusting an opening to increase an opening of the expansion valve until a set value is reached.   Each of the control means receives an intake pressure signal of the compressor, and when the signal is equal to or larger than a preset value corresponding to a high pressure cut value of the refrigerant, the opening degree of the expansion valve is set to 0. The reheat dehumidifying device according to any one of claims 1 to 8.   Each of the control means receives a discharge pressure signal of the compressor, and sets the opening of the expansion valve to 0 when the signal is equal to or higher than a preset value according to a high pressure cut value of the refrigerant. The reheat dehumidifying device according to any one of claims 1 to 8. A main refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected;
A bypass circuit for hot gas defrost branched from the middle of a high-pressure gas pipe connecting the compressor and the condenser, and connected to a low-pressure gas pipe connecting the expansion valve and the evaporator via an on-off valve;
In the air conditioner in which the evaporator and the condenser are installed in the same air temperature and humidity space,
During the hot gas defrost operation, on the compressor suction side, based on the suction temperature signal on the compressor suction side and the suction pressure signal on the suction side of the compressor or the evaporator inlet temperature signal on the inlet of the evaporator. When the calculated intake superheat degree is equal to or greater than a predetermined set value, the opening adjustment is performed to increase the opening degree of the expansion valve, and the calculated intake superheat degree is smaller than the set value. An air conditioning apparatus comprising suction superheat degree control means for adjusting the opening degree to reduce the opening degree of the expansion valve.   The suction superheat degree control means adjusts the opening degree to reduce the opening degree of the expansion valve at the start of hot gas defrost operation, calculates the suction superheat degree, and the calculated suction superheat degree is larger than the set value. The air conditioner according to claim 11, wherein opening adjustment is performed to increase the opening of the expansion valve as it goes. A main refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected;
A bypass circuit for hot gas defrost branched from the middle of a high-pressure gas pipe connecting the compressor and the condenser, and connected to a low-pressure gas pipe connecting the expansion valve and the evaporator via an on-off valve;
In the air conditioner in which the evaporator and the condenser are installed in the same air temperature and humidity space,
During hot gas defrost operation, the discharge superheat degree on the compressor discharge side is calculated based on the discharge pressure signal and discharge temperature signal on the compressor discharge side, and the calculated discharge superheat degree is equal to or greater than a predetermined set value. Discharge superheat degree control that adjusts the opening degree to increase the opening degree of the expansion valve, and adjusts the opening degree to reduce the opening degree of the expansion valve when the calculated discharge superheat degree is smaller than the set value Means for providing an air conditioner.   The discharge superheat degree control means adjusts the opening degree to reduce the opening degree of the expansion valve at the start of hot gas defrost operation, calculates the discharge superheat degree, and the calculated discharge superheat degree is larger than the set value. 14. The air conditioner according to claim 13, wherein opening adjustment is performed to increase the opening of the expansion valve. A main refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected;
A bypass circuit for hot gas defrost branched from the middle of a high-pressure gas pipe connecting the compressor and the condenser, and connected to a low-pressure gas pipe connecting the expansion valve and the evaporator via an on-off valve;
In the air conditioner in which the evaporator and the condenser are installed in the same air temperature and humidity space,
When the hot gas defrost operation is started, the opening of the expansion valve is adjusted so that the opening of the expansion valve is reduced. After a predetermined time has elapsed, a pressure signal is received from a discharge pressure sensor provided on the discharge side of the compressor, An air conditioning apparatus comprising discharge pressure control means for adjusting an opening degree to increase the opening degree of the expansion valve until a set value is reached. A main refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected;
A bypass circuit for hot gas defrost branched from the middle of a high-pressure gas pipe connecting the compressor and the condenser, and connected to a low-pressure gas pipe connecting the expansion valve and the evaporator via an on-off valve;
In the air conditioner in which the evaporator and the condenser are installed in the same air temperature and humidity space,
When the hot gas defrosting operation is started, the opening of the expansion valve is adjusted to be small, and after a predetermined time has passed, a pressure signal is received from a suction pressure sensor provided on the suction side of the compressor, and the compressor suction pressure is set in advance. An air conditioning apparatus comprising suction pressure control means for adjusting an opening to increase an opening of the expansion valve until a set value is reached.

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