KR20200123603A - Heat pump and it's Control method - Google Patents

Abstract

The present invention relates to a heat pump control method. More specifically, a heat pump, in which a circuit including a compressor, a condenser, an expansion valve, and an evaporator is connected through a sealed refrigerant line, comprises a condenser fan, an evaporator fan, and a refrigerant (charge amount) control means (having a refrigerant storage space) for charging refrigerant to or recovering refrigerant from the circuit. The heat pump control method includes: a control to increase the condensation temperature while maintaining the evaporation temperature; a control to lower the condensation temperature; a control to increase the evaporation temperature while maintaining the condensation temperature; and a control to lower the evaporation temperature while maintaining the condensation temperature. The heat pump improves energy efficiency by minimizing a difference between high pressure and low pressure during operation of the heat pump.

Description

Heat pump and it's Control method}

The present invention relates to a heat pump and a control method thereof.

A heat pump is a device that transfers heat from a heat source to a destination called a “heater sink”. Heat pumps absorb heat in cold spaces and dissipate heat in warm spaces. That is, in the heat pump, heat energy is transferred in a direction opposite to the natural heat transfer direction. To this end, the heat pump uses a small amount of external energy to transfer energy from the heat source to the heat sink.

Air conditioners, refrigerators and air conditioners (HVAC: Heating Ventialating and Air Conditioning) are representative examples of heat pumps. In addition, devices using a heat pump include water purifiers, dryers, washing machines, and vending machines that provide cold/hot water.

In the case of an air conditioner, refrigerant is charged into the air conditioner so that the cooling mode operates even at the worst high temperature (the condensation temperature is high). Therefore, under other conditions (eg, low load conditions), there is a problem in that the energy efficiency of the heat pump is low because the excess refrigerant is present in the system.

In addition, in the conventional heat pump, if the amount of refrigerant compression per unit time of a variable capacity compressor such as an inverter compressor is increased, the gap between the high pressure and the low pressure becomes larger, thereby reducing the efficiency.

Application number KR 10-2013-0084665 (US 9,372,015 B2) Application number KR 10-2016-7026740 US 2016/0370044 A1) Application number KR 10-2007-0084960 US 2011/0041523 A1 US 7,010,927 B2 US 9,738,138 B2 US 2017/0059219 A1 US 2017/0115043 A1 WO 2018/025900 A1

It is derived in order to solve the problems of the prior art of the present invention. That is, it is intended to provide a heat pump and a control method thereof that improves energy efficiency by lowering the distance between high and low pressures while the heat pump is operating.

To this end, in the heat pump control method according to the present invention, a circuit including a compressor, a condenser, an expansion valve (hereinafter "first expansion valve") and an evaporator is connected through a sealed refrigerant line, and the condenser fan, the evaporator fan, and the above A method for controlling a heat pump comprising a refrigerant (charge amount) adjusting means (hereinafter referred to as "second expansion valve") for charging a refrigerant in a circuit or recovering refrigerant from the circuit, wherein the second expansion valve A recovery valve for recovery, a storage space for storing the refrigerant, and a charging valve for charging the refrigerant to the circuit are connected in series in the order, and the second expansion valve is between the inlet of the first expansion valve and the low pressure line. Installed, setting a target condensation temperature; When the condensation temperature is lower than the target condensation temperature, the refrigerant control means charges the circuit with a refrigerant; When the condensation temperature is higher than the target condensation temperature, the refrigerant refrigerant control means recovers the refrigerant from the circuit; Including, in daily operation, a predetermined amount of refrigerant passes through the second expansion valve; It is characterized by that.

At this time, when the supply of power required to control the second expansion valve is started, controlling the opening of the recovery valve (vvd) to be smaller than that of the charging valve (vvc) to empty the refrigerant in the storage space; After performing the operation, when the set initialization step time (s_init) elapses or the high pressure is higher than the target high pressure, reducing the opening degree of the charging valve vvc; It is preferable to further include.

In addition, in the refrigerant charging step and the recovery step, one of the charging valve (vvc) and the recovery valve (vvd) may fix the opening degree and control the other valve; It is preferable to further include.

In addition, the first expansion valve may include any one of a capillary tube, a thermal expansion valve (TXV), a pressure-sensitive expansion valve (PXV), or an electronic expansion valve (EEV); It is preferable to be.

In addition, the charging valve (vvc) and the recovery valve (vvd) include an orifice for bypassing the refrigerant; It is desirable to do.

To this end, the heat pump control method according to the present invention is, for this purpose, the heat pump control method according to the present invention is connected through a closed refrigerant line to a circuit including a compressor, a condenser, an expansion valve, and an evaporator, and a condenser fan, an evaporator. In the cooling mode control method of a heat pump comprising a fan and a refrigerant (charge amount) control means (having a refrigerant storage space) for charging a refrigerant into the circuit or recovering the refrigerant from the circuit, the method comprising: "condensation temperature while maintaining the evaporation temperature. To increase the control"; "Control to lower the condensation temperature while maintaining the evaporation temperature"; While maintaining the same heat exchange amount (Q = c·m·dT) of the condenser, the condenser fan power consumption is increased (i.e., the m is increased), and the compressor power consumption is lowered [more specifically, the condenser A calculation step of lowering the internal pressure (ie, condensing temperature) to reduce the dT)] and lowering the power consumption of the heat pump; And determining the minimum power consumption of the heat pump by performing the calculation when the condenser fan is driven below the maximum rated power consumption. It characterized in that it comprises a.

To this end, in the heat pump according to the present invention, a circuit including a compressor, a condenser, an expansion valve, and an evaporator is connected through a sealed refrigerant line, and the condenser fan, the evaporator fan, and the circuit are charged with refrigerant or refrigerant from the circuit. A heat pump comprising a refrigerant (charge amount) control means (having a refrigerant storage space) to be recovered, comprising: "control for increasing a condensation temperature while maintaining an evaporation temperature"; "Control to lower the condensation temperature while maintaining the evaporation temperature"; "Control to increase the evaporation temperature while maintaining the condensation temperature"; And "control to lower the evaporation temperature while maintaining the condensation temperature"; It characterized in that it comprises a.

To this end, in the heat pump control method according to the present invention, a circuit including a compressor, a condenser, an expansion valve, and an evaporator is connected through a sealed refrigerant line, and the condenser fan, the evaporator fan, and the circuit are charged with refrigerant or from the circuit. In the control method of a heat pump including a refrigerant (charge amount) adjusting means (with a refrigerant storage space) for recovering the refrigerant, the heat exchange amount (Q = c·m·dT) of the “heat exchanger” is kept the same, The power consumption of the “heat exchanger” fan is increased (ie, the m is increased), and the power consumption of the compressor is decreased [more specifically, the pressure inside the heat exchanger (ie, the boiling point of the refrigerant) is adjusted, and the dT Is small)] In the calculation for lowering the power consumption of the heat pump, the maximum power consumption of the outdoor heat exchanger fan is the maximum rated power consumption of the fan; It is characterized by being.

In this case, setting a target condensation temperature; And setting a target evaporation temperature.

In addition, it is preferable that the maximum amount of refrigerant stored in the refrigerant storage space is less than 1/2 of the total amount of refrigerant present in the heat pump.

In addition, when lowering the condensing temperature further, first, the power consumption of the condenser fan is further increased to increase the degree of subcooling, and the control means recovers the refrigerant from the circuit; And, when the evaporation temperature is further increased, first, the power consumption of the evaporator fan is further increased to increase the superheat degree, and the control means charges the refrigerant into the circuit; It is desirable.

In addition, it is preferable that some of the refrigerant circulating in the circuit in normal operation pass through the storage tank.

In addition, the refrigerant control means includes a function of separating the gas refrigerant and the liquid refrigerant; It is preferable to supply the separated gas refrigerant to a compressor.

In addition, the refrigerant control means comprises a return valve for recovering the refrigerant from the circuit, a storage space for storing the refrigerant, and a charging valve for charging the refrigerant to the circuit in series in the above order; And the refrigerant control means is installed between the outlet of the condenser and the low pressure line; It is desirable to do.

To this end, in the heat pump according to the present invention, a circuit including a variable capacity compressor, a condenser, an electronic expansion valve, and an evaporator is connected through a sealed refrigerant line, and a condenser fan, an evaporator fan, and a refrigerant charge in the circuit or the circuit A heat pump comprising a refrigerant (charge amount) adjusting means and a controller for recovering a refrigerant from the heat pump, the method comprising: setting a target high pressure (HP_t); Setting a target low pressure (LP_t); Setting a target subcooling degree (SC_t); And setting a target superheat degree (SH_t); wherein the controller adjusts the compressor to compress the amount of refrigerant per unit time corresponding to the size of the load (eg, in the case of an inverter compressor, set in response to the size of the load) Frequency), and the controller adjusts the speed of the condenser fan so that the subcooling at the outlet of the condenser is the target subcooling, and the controller, the compressor inlet pressure (evaporator outlet pressure) is the target low pressure Controls the expansion valve to be (LP_t), and the controller adjusts the speed of the evaporator fan so that the superheat degree at the evaporator outlet becomes the target superheat degree, and the controller controls the outlet pressure of the compressor ( It is characterized in that the refrigerant (charge amount) control means is adjusted so that the condenser inlet pressure) becomes the target pressure (HP_t).

To this end, in the heat pump according to the present invention, a circuit including a variable displacement compressor, a condenser, an expansion valve, and an evaporator is connected through a sealed refrigerant line, and a condenser fan, an evaporator fan, and a refrigerant are charged to the circuit or from the circuit. A heat pump comprising a refrigerant (charge amount) adjusting means for recovering refrigerant and a controller, the method comprising: setting a target high pressure (condensation temperature (HP_t)); And setting a target subcooling degree (SC_t). Including, wherein the controller controls the compressor to compress the amount of refrigerant per unit time in response to the size of the load (e.g., in the case of an inverter compressor, operates at a frequency set corresponding to the size of the load), and the controller The speed of the condenser fan is adjusted so that the subcooling is the target subcooling at the outlet of the condenser, and the controller adjusts the refrigerant (charge amount) so that the outlet pressure (condenser inlet pressure) of the compressor becomes the target pressure (HP_t). It is characterized by adjusting means.

In this case, setting a target low pressure [evaporation temperature (LP_t)]; And setting a target superheat degree (SH_t). Further comprising, the expansion valve is an electronic expansion valve (EEV); The controller controls the expansion valve so that the compressor inlet pressure (evaporator outlet pressure) becomes the target low pressure (LP_t), and the controller controls the evaporator fan speed so that the superheat degree at the evaporator outlet becomes the target superheat degree. It is desirable to do.

According to the heat pump control method of the present invention, there is an effect of providing a heat pump that improves energy efficiency by lowering the distance between high and low pressure as much as possible while the heat pump is operating, and a control method thereof.

1 is an example of a pH diagram according to the prior art.
2 is a diagram for helping understanding of the first to fourth controls of the present invention.
3 is an example of a ph diagram according to the present invention.
4 is an example of a control procedure of the present invention.
5 is an example of listing the types of control procedures of the present invention.
6 is an example of a heat pump circuit suitable for the present invention.
7 is another example of a heat pump circuit suitable for the present invention.
8 is another example of a heat pump circuit suitable for the present invention.
9 is another example of a heat pump circuit suitable for the present invention.
10 is an example showing a high-pressure waveform according to the present invention.
11 is another example of a heat pump circuit suitable for the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this case, it should be noted that the same components in the accompanying drawings are indicated by the same reference numerals as possible. Spatially relative terms "below", "beneath", "lower", "above", "upper", etc., as shown in the figure It can be used to easily describe the correlation between components and other components. In addition, in the present specification, the term "pressure" may be interpreted as "a temperature at which the refrigerant boils, condensation temperature, or evaporation temperature".

The terms used in the present specification are for describing exemplary embodiments and are not intended to limit the present invention. In this specification, the singular form also includes the plural form unless specifically stated in the phrase. As used herein, “comprises” and/or “comprising” refers to the recited elements, steps and/or actions excluding the presence or addition of one or more other elements, steps and/or actions. I never do that.

In addition, terms or words used in the present specification and claims described below should not be interpreted as being limited to a conventional or dictionary meaning, but should be interpreted as meanings and concepts consistent with the technical idea of the present invention. In addition, detailed descriptions of known configurations and functions that are determined to unnecessarily obscure the subject matter of the present invention will be omitted.

In the following description, for convenience, an ideal heat pump will be used unless otherwise specified.

An object of the present invention is to improve the performance (COP) of the heat pump while making the heat exchange amount of the heat exchanger the same. For this, there is a need for a method that can individually control the condensation temperature of the condenser and the evaporation temperature of the evaporator.

<Explanation of Core Concepts>

An air heat exchanger can calculate the heat exchange amount as Q = c·m·dT. Here, there are many combinations of m and dT that make Q equal. In the above equation, m can be interpreted as air volume, air weight, wind speed, heat exchanger fan speed, fan power consumption, etc. Here, c will be the air specific heat or proportionality coefficient. And the temperature difference dT (air temperature before passing through the heat exchanger-air temperature after passing through) can be changed by the difference between the temperature at which the refrigerant boils inside the heat exchanger and the temperature of the incoming air.

In more detail, if the heat exchanger temperature (the temperature at which the refrigerant boils in the heat exchanger) and the air temperature are the same, heat exchange does not occur. Accordingly, one of the methods of reducing the temperature difference dT is to reduce the difference between the temperature of the air flowing into the heat exchanger and the boiling temperature of the refrigerant inside the heat exchanger (hereinafter, "heat exchange temperature"). For this, it is necessary to adjust the heat exchange temperature by changing the internal pressure of the heat exchanger, and it is natural that this has a relationship with the power consumption of the compressor.

For passenger car air conditioners, the electric compressor capacity is about 3.5 kW, and the heat exchanger fan is about 150 W. Accordingly, if the heat exchange amount (Q = c·m·dT) of the heat exchanger is kept the same, the fan power consumption is increased and the compressor power consumption is reduced, the efficiency of the air conditioner will be improved. For this, it is necessary to individually control the condensation temperature and the evaporation temperature.

<Element description>

Hereinafter, an element technology for individually controlling the condensation temperature and the evaporation temperature will be described with reference to FIGS. 1 and 2.

Hereinafter, a process of injecting a refrigerant into a general air conditioner system will be described. When the installation of the air conditioner piping is completed, the inside of the piping is vacuumed with a vacuum pump. When the inside of the pipe becomes vacuum, the refrigerant box outside the air conditioner (on the electronic scale) and the low-pressure line are connected and the compressor is operated, and when the valve of the external refrigerant box is opened, the refrigerant is charged from the external refrigerant box to the heat pump. And, when the refrigerant of the set weight is charged, refrigerant charging is stopped. Then, high and low pressures are properly formed. For example, the first cooling cycle (81)-(82)-(83)-(84). Here, it can be seen that when the refrigerant is charged (hereinafter, "first control"), both high pressure (HP) and low pressure (LP) increase (1) (from vacuum to low pressure and from vacuum to high pressure). Conversely, when the refrigerant is recovered (hereinafter, "second control"), it can be seen that both the high pressure (HP) and the low pressure (LP) (from low pressure to vacuum and from high pressure to vacuum) decrease (2).

In other words, if a refrigerant is additionally charged to the low pressure of the circuit in a cooling circuit in which high and low pressures are properly formed, the added refrigerant is not all at low pressure (until high and low pressures are stabilized). Part of it will move under high pressure. Here, it can be seen that when the refrigerant is charged, both the high pressure (HP) and the low pressure (LP) increase (1). Conversely, when the refrigerant is recovered, it is natural that both the high pressure (HP) and the low pressure (LP) decrease (2).

When the first cooling cycle (81)-(82)-(83)-(84) is formed, the operation of closing the expansion valve further or increasing the amount of refrigerant compression per unit time of the compressor (either or both) (Hereinafter, "the third control" in which the difference between high and low pressure increases), the high pressure (HP) increases and the low pressure (LP) decreases (3), so that the second cooling cycle (91)-(92)-(93) )-(94) can be In addition, the operation of further opening the expansion valve while the second cooling cycle (91)-(92) -(93)-(94) is formed or reducing the amount of refrigerant compression per unit time of the compressor (either or both) (Hereinafter, "the fourth control" in which the difference between high and low pressure decreases), high pressure (HP) decreases and low pressure (LP) increases (4), so that the first cooling cycle (81)-(82)-(83) )-(84) can be Here, when performing the third and fourth control by the expansion valve, it is preferable to use an electronic expansion valve (EEV). And, when performing the third and fourth control by the compressor, it is preferable to use an inverter compressor having a variable operating frequency. It is also desirable to use a compressor whose stroke distance changes during one compression.

When the first control (1) or the second control (2) is performed, both the high and low pressures increase (UU) or decrease (DD), and the third control (3) or the fourth control (4) increases the high pressure ( When u), the low pressure decreases (d), and when the high pressure decreases (d), the low pressure increases (u). Accordingly, when a control in which the two pressures move in one direction and a control that moves in the opposite direction are combined, the pressure on the other side can be adjusted while maintaining the pressure on one side.

For example, if the first control (1) and the third control (3) are performed simultaneously or sequentially, the high pressure increases and the low pressure cancels out and thus may not fluctuate. (Hereinafter, "the step of increasing the condensation temperature while maintaining the evaporation temperature") In addition, if the first control (1) and the fourth control (4) are performed simultaneously or sequentially, the low pressure increases and the high pressure is canceled and thus does not change. I can. (Hereinafter, "the step of increasing the evaporation temperature while maintaining the condensation temperature") In addition, if the second control (2) and the third control (3) are performed simultaneously or sequentially, the low pressure decreases and the high pressure is canceled and thus does not change. I can. (Hereinafter, "the step of lowering the evaporation temperature while maintaining the condensation temperature") In addition, if the second control (2) and the fourth control (4) are performed simultaneously or sequentially, the high pressure decreases and the low pressure is canceled and thus does not change. I can. (Hereinafter, "the step of lowering the condensation temperature while maintaining the evaporation temperature") At this time, it is preferable to keep the degree of supercooling and the degree of superheat at the design values as much as possible.

If the third control 3 and the fourth control 4 are performed, the amount of refrigerant circulation per unit time can be adjusted without changing the high and low pressures. More specifically, in the third control, the difference between high and low pressure is further increased by increasing the amount of refrigerant compression per unit time of the compressor, and in the fourth control, when the difference between high and low pressure is further reduced by opening the expansion valve further, the high and low pressure fluctuates. However, the amount of refrigerant circulating in the circuit per unit time can be further increased. On the other hand, it is natural that the amount of refrigerant circulating in the circuit can be further reduced by changing the object of the third control and the fourth control. (Hereinafter, "the step of controlling the amount of heat exchange while maintaining the condensation temperature and the evaporation temperature")

In the above, a method of individually controlling high pressure and high pressure has been described.

Hereinafter, an embodiment of controlling the evaporation temperature to be higher in the heat pump according to the present invention (air conditioner cooling mode) will be described with reference to FIGS. 2 to 4. 4 is an example of a procedure of controlling the evaporation temperature of the evaporator to be higher.

In Fig. 4, the control procedure 100 is an example in which the fourth control and the first control are performed twice in succession. If the fourth control is performed in the initial state (L0), the high pressure decreases, and the low pressure rises to become the state (L1). The evaporation temperature became higher as the low pressure rose as desired, but the condensation temperature was lower than the target condensation temperature (HP_t) due to the high pressure drop. Here, when the first control is performed, the refrigerant is charged, so that both high and low pressures rise to enter the state L2. That is, the evaporation temperature of the low pressure rises further, so that the evaporation temperature becomes closer to the target evaporation temperature LP_t, and the high pressure maintains the target condensation temperature HP_t. State (L3) and state (L4) show that the fourth control and the first control are sequentially repeated one more time (in other words, the step of increasing the evaporation temperature while maintaining the condensation temperature is performed once more). Then, the low pressure rises along the (LP_rise) to reach the target low pressure (LP_t). In the control sequence 100, the first control may be referred to as "the step of charging the refrigerant", "the step of increasing the evaporation temperature", and "the step of adjusting to maintain the condenser target temperature HP_t". In addition, the fourth control may be referred to as “a step of increasing the evaporation temperature”.

In FIG. 4, the control procedure 101 uses the fourth control and the first control in the same manner as the control procedure 100, but is a case in which the first control is performed first. When the first control is performed in the initial state L0a, the refrigerant is charged, so that both the high and low pressures rise, and the state L1a is established. The evaporation temperature was higher because the low pressure was raised as desired, but the condensation temperature was higher than the target condensation temperature (HP_t) because the high pressure also rose. Here, when the fourth control is performed, the high pressure decreases and the low pressure rises, resulting in a state L2a. That is, the evaporation temperature of the low pressure rises further, so that the evaporation temperature becomes closer to the target evaporation temperature LP_t, and the high pressure maintains the target condensation temperature HP_t. State (L3a) and state (L4a) show that the first control and the fourth control are sequentially repeated one more time (in other words, the step of increasing the evaporation temperature while maintaining the condensation temperature is performed once more). Then, the low pressure rises along the (LP_rise) to reach the target low pressure (LP_t). In the control procedure 101, the first control may be referred to as "the step of charging the refrigerant" and "the step of increasing the evaporation temperature". In addition, the fourth control may be referred to as "a step of adjusting to maintain the condenser target temperature HP_t" and "a step of increasing the evaporation temperature".

In the above, when the target evaporation temperature of the evaporator is set higher than the current evaporation temperature, a method of achieving the target evaporation temperature while maintaining the condensation temperature of the condenser has been described in detail.

In FIG. 5, the control sequence 200 sets a target condensation temperature (HP_t) of the condenser higher than the current condensation temperature (HP_0), and achieves the target condensation temperature (HP_t) while maintaining the evaporation temperature (LP_t) of the evaporator. This is an example showing that. Here, the first control for charging the refrigerant and the third control for increasing the difference between the high and low pressures are used (in other words, a step of increasing the condensation temperature while maintaining the evaporation temperature is performed). In the control sequence 200, the first control may be referred to as "the step of charging the refrigerant" and "the step of increasing the condensation temperature". In addition, the third control may be referred to as "a step of adjusting to maintain the evaporator target temperature LP_t" and "a step of increasing the condensation temperature".

In FIG. 5, the control procedure 150 sets the target evaporation temperature LP_t of the evaporator lower than the current evaporation temperature LP_0, and achieves the target evaporation temperature LP_t while maintaining the condensation temperature HP_t of the condenser. This is an example showing that. Here, a second control for recovering the refrigerant and a third control for increasing the difference between the high and low pressures are used (in other words, the step of lowering the evaporation temperature while maintaining the condensation temperature is executed). In the control sequence 150, the second control may be referred to as "recovering the refrigerant", "lowering the evaporation temperature", and "adjusting the condenser to maintain the target condensation temperature HP_t". In addition, the third control may be referred to as “lowering the evaporation temperature”.

In FIG. 5, the control sequence 250 sets the target condensation temperature HP_t of the condenser lower than the current condensation temperature HP_0, and achieves the target condensation temperature HP_t while maintaining the evaporation temperature LP_t of the evaporator. This is an example showing that. Here, a second control for recovering the refrigerant and a fourth control for reducing the difference between the high and low pressures are used (in other words, a step of lowering the condensation temperature while maintaining the evaporation temperature is executed). In the control sequence 250, the second control may be referred to as "recovering the refrigerant" and "lowering the condensation temperature". In addition, the fourth control may be referred to as "adjusting to maintain the evaporator target temperature LP_t" and "lowering the condensation temperature".

When the conventional air conditioner is operated to some extent and the cooling load is reduced, the outdoor unit and the indoor unit fan rotate at a maximum speed or less. In addition, since the conventional air conditioner cannot individually adjust the evaporation temperature and the condensation temperature, the efficiency (COP) cannot be increased while maintaining the same load (heat exchange amount).

According to this embodiment, the condensation temperature of the condenser can be lowered while the evaporation temperature of the evaporator is not changed. Therefore, when the cooling load is less than the maximum rating, the air conditioner's performance (COP) is achieved by reducing the power consumption of the compressor and increasing the power consumption of the outdoor unit fan while maintaining the same heat exchange amount (Q = c·m·dT) of the outdoor heat exchanger. Can increase. Here, increasing the power consumption of the fan of the outdoor unit is "higher the rotational speed of the fan of the outdoor unit." It is natural that it can be interpreted as "more weight of air conveyed per unit time". In addition, it is natural that reducing the power consumption of the compressor includes reducing the power consumption of the compressor when the difference between the high pressure and the low pressure decreases as shown in the control procedures 100 and 250 without separately controlling the compressor.

In addition, when a conventional air conditioner without a refrigerant (charge amount) control means is operated to some extent and the cooling load is reduced, the indoor unit fan rotates at a low speed. According to this embodiment, even if the evaporation temperature of the evaporator is changed, the condensation temperature of the condenser does not change. Therefore, when the cooling load is less than the maximum rating, the air conditioner's performance (COP) is achieved by reducing the power consumption of the compressor and increasing the power consumption of the indoor unit fan while maintaining the same heat exchange amount (Q = c·m·dT) of the indoor heat exchanger. Can increase. At this time, the compressed refrigerant volume per second of the compressor decreases. However, since the low pressure increases, the amount of refrigerant compressed once increases, and the amount of refrigerant compressed per second does not decrease proportionally as the compressed volume decreases.

In the heat pump according to the present invention, the power consumption of the compressor should be reduced and the power consumption of the heat exchanger fan should be increased in order to increase efficiency. In the case of the indoor unit fan, it is desirable to increase it to the extent that people do not feel unpleasant. On the other hand, in consideration of energy saving, the maximum power consumption of the indoor heat exchanger fan is preferably the maximum rated power consumption of the fan. In the case of a vehicle, a person may not be able to feel the noise of the fan due to the inflow of external noise caused by vehicle operation. In addition, since there are people who are sensitive to noise and those who are insensitive, it is difficult to set the power consumption of the fan, which starts to feel unpleasant, as a single value. Accordingly, when the user inputs a predetermined power consumption when the vehicle is stopped, it is preferable to set the power consumption of the fan that starts feeling unpleasant for each vehicle driving condition by referring to the input value.

And, in the case of the outdoor unit fan, it is preferable to increase the noise of the outdoor unit to the extent that the noise of the outdoor unit does not flow into the room so that people do not feel uncomfortable. It is natural that the fan of the outdoor unit can be driven with the maximum power allowed in the case of good sound insulation between the indoor and the outdoor.

In the above description, it can be seen that in the heat pump according to the present invention, when the target temperature is increased, the refrigerant must be charged in the cooling circuit 100 and 200. In addition, it can be seen that when the target temperature decreases (150 and 250), the refrigerant must be recovered from the cooling circuit.

It is natural that the heat pump control concept of the present invention can also be applied to heating. Therefore, the step of setting the target evaporation temperature of the air conditioner is preferably interpreted as "setting the heat exchange temperature of the internal heat exchanger by referring to the heat exchange load of the indoor heat exchanger". In addition, the step of setting the target condensation temperature of the air conditioner is preferably interpreted as “a step of setting the heat exchange temperature of the external heat exchanger by referring to the heat exchange load of the outdoor heat exchanger”.

Hereinafter, an example of a heat pump 600 suitable for the present invention will be described with reference to FIG. 6.

The heat pump 600 is connected through a refrigerant line in which a "circuit" including a compressor (C), a condenser (HEX_C), an expansion valve (EXV), and an evaporator (HEX_E) is sealed. In addition, a refrigerant storage tank RS1 is installed in parallel with the expansion valve EXV. Between the inlet of the expansion valve (EXV) and the inlet of the tank (RS1), a recovery valve (vvd) for recovering the refrigerant from the "circuit" is installed. And between the outlet of the expansion valve (EXV) and the outlet of the tank (RS1), a charging valve (vvc) for charging the refrigerant with a "circuit" is installed.

Here, the refrigerant storage tank RS1, the recovery valve vvd, and the charging valve vvc charge a refrigerant in the "circuit" or recover the refrigerant from the "circuit" (hereinafter, "refrigerant (charge amount) ) Adjustment means").

Hereinafter, a method of charging the refrigerant when the heat pump 600 is installed will be described. First, after installing the heat pump 600 piping, all valves (EXV) (vvd) (vvc) are opened, and the "circuit" and the inside of the refrigerant storage tank RS1 are made into a vacuum state by using a vacuum pump. And completely close the return valve (vvd). When the refrigerant cylinder outside the heat pump 600 is connected to the inlet of the compressor C, the compressor C is operated, and the valve of the external refrigerant cylinder is opened, the refrigerant is charged from the external refrigerant cylinder to the heat pump 600. When the specified amount of refrigerant is charged, the external refrigerant cylinder valve is completely closed. Through the above procedure, it is possible to implement the condensation temperature and evaporation temperature as in a heat pump without a conventional refrigerant (charge amount) control means.

Hereinafter, a second control for recovering the refrigerant from the "circuit" of the heat pump 600 and storing it in the refrigerant storage tank RS1 will be described. First, when the refrigerant recovery valve vvd is opened, the high pressure in the "circuit" is high, and the inside of the storage tank RS1 is vacuum, so that the condensed refrigerant is recovered from the "circuit" to the storage tank RS1 and expands. When a certain amount of refrigerant is recovered to the storage tank RS1, the refrigerant may no longer be recovered. At this time, when the refrigerant charging valve (vvc) is slightly opened to discharge the gas inside the storage tank (RS1), refrigerant recovery continues. Meanwhile, when opening the refrigerant charging valve vvc, it is preferable to slightly close the expansion valve EXV so that the amount of refrigerant flowing into the evaporator HEX_E is the same as before the operation of the charging valve vvc.

Hereinafter, a first control for charging a refrigerant in the "circuit" of the heat pump 600 will be described. When the recharge valve (vbc) is opened (slightly) while the recovery valve (vvd) is closed, the gas refrigerant inside the refrigerant storage tank (RS1) is moved by the suction power of the compressor and is charged into the "circuit". Finally, the refrigerant is charged in the "circuit" until the pressure of the low pressure line and the internal pressure of the refrigerant storage tank RS1 become the same.

Since the third control and the fourth control are the same as those of the first embodiment, detailed descriptions are omitted.

As described above, the first to fourth controls are possible in the heat pump 600. Therefore, it is natural that the condensation temperature and the evaporation temperature can be individually adjusted when the heat pump 600 is driven by using the procedure described in this embodiment.

On the other hand, after a long time elapses after both the refrigerant charging valve (vvc) and the recovery valve (vvd) are closed, the refrigerant inside the refrigerant storage tank RS1 vaporizes, so that the pressure of the storage tank RS1 may be higher than the internal pressure of the condenser. Then, when recovering the refrigerant, it may take longer than usual to recover the refrigerant. Therefore, rather than normally locking both the refrigerant charging valve (vvc) and the recovery valve (vvd), most of the refrigerant circulating in the "circuit" (eg, 98% refrigerant circulation amount) circulates through the expansion valve (EXV), It is preferable that a part of the circulating refrigerant (e.g. 2% refrigerant circulation amount) always passes through the storage tank RS1 so that the pressure inside the storage tank RS1 is between high and low pressures.

The heat pump 700 of FIG. 7 illustrates a case in which a refrigerant charging valve vvc is installed between the storage tank RS2 and the inlet of the compressor C. The storage tank RS2 of the heat pump 700 is preferably installed in an outdoor unit. In addition, since the refrigerant storage tank RS1 is installed in parallel with the expansion valve EXV in the heat pump 600, the storage tank RS1 is preferably installed in the indoor unit. When the indoor unit space is narrow, such as in an automobile, the heat pump 700 may be preferable.

Hereinafter, an example of a heat pump 800 suitable for the present invention will be described with reference to FIG. 8.

The heat pump 800 constitutes a heat pump "circuit" by connecting the compressor C, the condenser HXE_C, the mechanical first expansion valve EXV1, and the evaporator HEX_E through a sealed refrigerant line. In addition, a second electronic expansion valve EXV2 is installed in parallel with the expansion valve EXV1. The amount of refrigerant supplied to the evaporator HEX_E is controlled by the first expansion valve EXV1 and the second expansion valve EXV2. Here, the second expansion valve is a recovery valve (vvd) for recovering the refrigerant, a refrigerant storage tank (RS3), and a charging valve (vvc) for charging the refrigerant are connected in series. The second expansion valve EXV2 may be formed as a single body or may be formed by assembling the parts.

The second expansion valve EXV2 serves to expand the refrigerant, and to charge the refrigerant in the “circuit” or to recover the refrigerant from the “circuit” (hereinafter, “refrigerant (charge amount) control means”). In this case, it is preferable that the maximum amount of refrigerant that can be stored in the storage tank RS3 is 1/2 or less of the total amount of refrigerant present in the heat pump 800. Here, the mechanical first expansion valve EXV1 may be a capillary tube or a thermal expansion valve TXV.

Hereinafter, a preferred driving example of the heat pump 800 will be described.

First, the refrigerant recovery valve (vvd) inside the second expansion valve (EXV2) is completely closed, and the refrigerant charging valve (vvc) is completely opened. And it drives the compressor at the maximum design power consumption. Then, a design pressure that maximizes the difference between high and low pressure is formed. At this time, all of the refrigerant supplied to the evaporator HEX_E flows through the first expansion valve EXV1.

Hereinafter, a method of recovering the refrigerant will be described. The recovery valve (vvd) and the charging valve (vvc) so that the amount of refrigerant flowing into the refrigerant storage tank (RS3) through the recovery valve (vvd) inside the second expansion valve is greater than the amount of refrigerant flowing out through the charging valve (vvc). Adjust the opening degree. Then, the amount of refrigerant stored in the storage tank RS3 increases, and the amount of refrigerant supplied to the evaporator HEX_E decreases. (How to recover refrigerant from circuit)

Hereinafter, a method of charging the refrigerant will be described. The recovery valve (vvd) and the charging valve (vvc) so that the amount of refrigerant flowing into the refrigerant storage tank (RS3) through the recovery valve (vvd) inside the second expansion valve is reduced so that the amount of refrigerant flowing through the charging valve (vvc) is reduced. Adjust the opening degree. Then, the amount of refrigerant stored in the storage tank RS3 decreases, and the amount of refrigerant supplied to the evaporator HEX_E increases. (How to charge the refrigerant in the circuit)

Reducing the pressure difference between high and low pressure while maintaining the same heat exchange amount (Q = c·m·dt) in the heat exchanger controls the amount of refrigerant stored in the second expansion valve EXV2 [Refrigerant (charge amount) control function] It is desirable to do so. In addition, it is preferable to control (expansion valve function) the amount of refrigerant supplied to the evaporator (HEX_E) by the amount of refrigerant passing through the recovery valve (vvd) the storage tank (RS3) and the charging valve (vvc).

In the case of lowering the high pressure, for example, in the case of lowering (92)-(93) to (82)-(83) in Fig. 1, first increase the power consumption of the condenser fan to increase the subcooling degree ("while increasing" Concept including), it is preferable to achieve by recovering the refrigerant with the refrigerant (charge amount) control means. This is because when the refrigerant is recovered, the condensation temperature decreases and the degree of subcooling decreases [see Figs. 1 (92)-(93) and (82)-(83)].

In the case of increasing the low pressure, example In the case of increasing the (14)-(11) to (14b)-(11b) in Fig. 3, first increase the power consumption of the evaporator fan to increase the superheat degree ("while increasing" Concept including), it is preferable to achieve by charging the refrigerant with the refrigerant (charge amount) control means. This is because it is desired to prevent hydraulic compression from occurring in the compressor while the low pressure is changing.

When the conventional air conditioner without a refrigerant (charge amount) control means is operated to some extent and the cooling load is reduced, the indoor unit fan rotates at a low speed. And at this time, the condensation temperature of the condenser and the evaporation temperature of the evaporator could not be adjusted.

According to this embodiment, it is possible to increase the evaporation temperature of the evaporator while maintaining the condensation temperature of the condenser. Therefore, when the cooling load is less than the maximum rating, the air conditioner's performance (COP) is achieved by reducing the power consumption of the compressor and increasing the power consumption of the indoor unit fan while maintaining the same heat exchange amount (Q = c·m·dT) of the indoor heat exchanger. Can increase. Here, it is natural that increasing the power consumption of the outdoor unit fan can be interpreted as “more increasing the rotational speed of the outdoor unit fan” or “more increasing the weight of air transferred per unit time”. In addition, it is natural that reducing the power consumption of the compressor includes reducing the power consumption of the compressor when the difference between the high pressure and the low pressure decreases as shown in the control procedures 100 and 250 without separately controlling the compressor.

Among the matters to be noted in carrying out the present invention, the first is to perform heat insulation construction on the refrigerant (charge amount) control means. An intermediate pressure between high and low pressure is formed in the storage space inside the refrigerant control means. When a liquid refrigerant flows into the storage space through a recovery valve (vvd), some of the phases change to gas, and the ratio of liquid/gas varies depending on the storage space pressure. [Refer to Fig. 1, (93)-(94)] If heat insulates from outside or leaks out due to poor insulation, the ratio of liquid gas changes, which can form unwanted liquid-gas ratio. Because. And secondly, attention should be paid to the selection of the physical location where the return valve (vvd) and the filling valve (vvc) are connected to the storage space. This is because if the location is incorrectly selected, the refrigerant is operated so that the refrigerant flows out of the storage space, but the refrigerant does not flow out and may continue to lump in the storage space.

9 heat pump 900 removes the first expansion valve EXV1 from FIG. 8 heat pump 800, changes the refrigerant storage tank RS3 to a storage tank RS4 capable of gas-liquid separation, and The gas inside the separator (RS4) is injected into the compressor (C) (the broader term is "supply"). Since the method of charging and recovering the refrigerant can be performed on the same principle as the heat pump 800, a detailed description will be omitted.

Hereinafter, an example of a method of controlling the heat pump 800 suitable for the present invention will be described with reference to FIGS. 8 and 10.

The configuration of the heat pump 800 in FIG. 8 is omitted since it has been described in detail in the preceding description. However, in this embodiment, the first expansion valve EXV1 is a capillary tube, a temperature sensitive type (hereinafter, ““TXV””), a pressure sensitive type (hereinafter, ““PXV””), an electronic type (hereinafter, ““EEV”) Expansion valves such as ”) may be used.

In this embodiment, TXV will be described as the first expansion valve EXV1. Except for the second expansion valve (EXV2), the rest of the parts are controlled independently. More specifically, the control of the compressor (C), the condenser fan (FN_C), and the degree of subcooling is managed by an independent controller. In addition, the second expansion valve EXV2 is managed by another independent controller with reference to the condensation temperature (the temperature at which the refrigerant boils at high pressure, hereinafter may also be referred to as “high pressure”). (Of course, one controller can control simultaneously with two independent control routines.)

Hereinafter, an example of a preferred control procedure of the second expansion valve EXV2 in the heat pump 800 will be described. For convenience of explanation, it is assumed that the same amount of refrigerant passes through the two valves when the opening degrees of the recovery valve vvd and the charging valve vvc are the same, and more refrigerant passes through the two valves when the opening degree is larger. In practice, it is natural that the pressure difference at both ends of each valve may differ from the above assumption.

<Initialization step (s_init)>

When the supply of power required to control the second expansion valve EXV2 is started, a step (s_init) of emptying the refrigerant in the storage space by controlling the opening degree of the recovery valve vvd to be smaller than the charging valve vvc is performed. Conduct. As a specific value, for example, the opening degree of the recovery valve (vvd) is set to 2%, and the opening degree of the filling valve (vvc) is set to 100%. When the compressor (C) starts to operate, the condensation temperature (cv_2) rises.

When the set initialization step (s_init) time elapses or the high pressure becomes higher than the target high pressure, the opening degree of the charging valve vvc is reduced (from 100% to 2%) and the initialization step is terminated. The target high pressure can be determined by making the difference between the condensing temperature and the temperature of the air exchanging heat with the condenser be a constant value.

<High pressure control stage (hp_ctrl)>

The opening degree of the filling valve (vvc) is fixed, and the target high pressure is achieved by controlling the recovery valve (vvd). If the opening degree of the recovery valve vvd is larger than that of the charging valve vvc, the refrigerant is recovered from the circuit and stored in the storage space RS3 inside the expansion valve EXV2 (hereinafter, “refrigerant recovery step”). Conversely, when the opening degree is smaller, the refrigerant is charged from the storage space RS3 to the circuit (hereinafter, “refrigerant charging step”). The high pressure is measured and compared with the target high pressure, and the target high pressure can be achieved by controlling the recovery valve vvd. It is natural that it can be implemented with PID, PI, and fuzzy control, which are widely used in the industry.

It is also possible to achieve the target high pressure by fixing the recovery valve (vvd) and controlling the filling valve (vvc). This is because the relative opening degrees of the two valves determine charging and recovery of the refrigerant. Here, the opening degree of the fixed valve is determined by “how to distribute the refrigerant to the first expansion valve EXV1 and the second expansion valve EXV2 in daily operation””.

If the high pressure fluctuates little by little in the vicinity of the target high pressure due to refrigerant charging/recovery, TXV will work as well as when refrigerant is not recharged/recovered. In this case, it is natural that the TXV opening is proportional to the size of the cooling load. And, it is natural that the EEV, which is commonly used for superheat control, works well even when the first expansion valve EXV1 is used.

The total amount of refrigerant charged in the circuit and the difference between the high and low pressures are proportional. However, it should be noted that if there are components in the circuit that can store the refrigerant (eg receiver, accumulator……), they may not be proportional. Meanwhile, it is preferable to obtain the maximum amount of refrigerant stored in the second expansion valve EXV2 using the selection criteria of the receiver dryer.

By adding an orifice for bypassing the refrigerant inside the charging valve vvc and the recovery valve vvd, the orifice serves as a capillary tube that bypasses the second expansion valve EXV2, that is, the first expansion valve EXV1. can do.

And, it is natural that the control method described above can also be applied to the heat pump 900 of FIG. 9. At this time, it is preferable that the filling valve (vvc) and the recovery valve (vvd) have orifices that bypass the valves inside the valves. In addition, it is preferable that the valves have a minimum opening degree so that they cannot be set below that. Here, the orifice and the minimum opening degree serve as the first expansion valve EXV1. That is, the second expansion valve EXV1 also serves as the first expansion valve EXV1. When controlling the superheat degree by the second expansion valve EXV2, it is preferable to simultaneously reduce and increase the opening degrees of the first expansion valve and the second expansion valve.

In the heat pump 900, the target condensation temperature may be adjusted based on the opening degree of the second expansion valve EXV2. More specifically, a large opening degree means that a large amount of refrigerant passes through, and thus a large amount of heat exchange is required in the condenser. In this case, increasing the condensation temperature increases the heat exchange capacity of the heat exchanger. Conversely, if the opening degree is small, the target condensation temperature can be lowered.

The refrigerant that has passed through the second expansion valve EXV2 is directly supplied to the inlet of the compressor and may be used for cooling the compressor (including an injection function). In this case, if the flow rate passing through the second expansion valve EXV2 is too large, the efficiency is lowered, so it is required to control the flow of an appropriate amount of refrigerant.

Hereinafter, an example of a method for controlling a cooling mode of the heat pump 600 suitable for the present invention will be described with reference to FIG. 6. The circuit configuration of the heat pump 600 has been described above and thus will be omitted.

In this embodiment, the controller performs control as follows.

1) Variable capacity compressor: Compressor C compresses the set amount of refrigerant per unit time. For example, in the case of the inverter compressor C, it operates at a set frequency corresponding to the size of the load. In other words, the set frequency is calculated and calculated from the difference between the actual temperature and the target temperature inside the space to be cooled. If the low pressure and superheat degree are kept constant, the amount of refrigerant compressed by the inverter compressor C per unit time will be constant for each frequency. Hereinafter, for convenience of explanation, it will be described using an inverter compressor (C). At this time, it should be noted that the frequency of the inverter compressor represents the amount of refrigerant compression per unit time. (Hereinafter, “refrigerant compression amount control per unit time”)

2) Condenser: The condenser fan (FN_C) operates so that the subcooling degree (SC) of the refrigerant measured at the outlet of the condenser (HEX_C) becomes the target subcooling degree (SC_t). (Hereinafter, “subcooling control with a condenser fan”)

3) Expansion valve: The expansion valve (EXV) is operated so that the inlet pressure (evaporator outlet pressure) of the compressor (C) becomes the target pressure (LP_t). More specifically, a controller (not shown) controls the inlet pressure of the compressor C (evaporator outlet pressure) by adjusting the opening degree of the expansion valve EXV. To this end, the expansion valve EXV is preferably an electronic expansion valve EEV. When the expansion valve (EEV) is opened more than the current one, more refrigerant than the current one goes down to the low pressure and the low pressure rises. On the contrary, if the expansion valve (EEV) is closed more than the present, less refrigerant than the present goes down to the low pressure and the low pressure goes down. (Hereinafter “low pressure control with expansion valve”)

4) Evaporator: The evaporator fan (FN_E) operates so that the superheat (SH) of the refrigerant measured at the outlet of the evaporator (HEX_E) becomes the target superheat (SH_t). (Hereinafter, “superheat control with an evaporator fan”)

5) Refrigerant (charging amount) control means: [Consisting of storage tank (RS1), recovery valve (vvd) and charging valve (vvc)] Refrigerant (charging amount) control means is the outlet pressure (condenser inlet pressure) of the compressor (C) It operates so that it becomes this target pressure (HP_t). The operation method of the refrigerant (charge amount) control means (second expansion valve) in the fourth embodiment has been described in detail with reference to FIGS. 8 to 10, and thus description thereof will be omitted. [Hereinafter, “high pressure control with refrigerant (charge amount) control means”]

6) Target condensation temperature setting: It is preferable that the target high pressure (HP_t) [condensation temperature (Tc)] is higher than the outside air temperature by a predetermined value (c1) by referring to the outside air temperature (Ta). It is also desirable to set it with reference to the outside temperature and the load size. If this is expressed as a formula, an example can be given as follows.

Tc = Ta + c1

Example) c1=10.0, Tc = Ta + 10.0 regardless of the load size

Tc = Ta + c1 + c2 x load / rated load

Example) If c1=10.0, c2=1.0, rated load=10.0 kW, load= 2kW, then Tc=Ta + 10.2 ℃, if load= 4kW, Tc=Ta + 10.4℃

On the other hand, it is natural that the target condensation temperature can be obtained through a number of preceding experiments in various environments (eg, outside air temperature, load, low pressure...), and that the obtained value can be used by the controller.

7) Target evaporation temperature setting: For air conditioners, it is desirable to set the value between 0 and 15 ℃. It is preferable that the betting temperature is higher by a predetermined value e1 than the betting temperature, referring to the betting temperature Tin. It is also desirable to set with reference to the inner air temperature (Tin) and the load size. If this is expressed as a formula, an example can be given as follows. It is natural that it is desirable to lower the target evaporation temperature when the cooling load is large.

Te = Tin-e1

Example) e1=15.0, Te = Tin-15.0 regardless of the load size

Te = Tin-(e1 + e2 x load / rated load)

Example) e1=10.0, e2=10.0, rated load=10.0 kW

If load= 3kW, Te=Tin-13.0 ℃

If load= 9kW, Te=Tin-19.0 ℃

On the other hand, it is natural that the target evaporation temperature can be obtained through a number of preceding experiments in various environments (eg, internal air temperature, load, high pressure...), and that the obtained value can be used by the controller.

Hereinafter, with reference to the control procedure 100 of FIG. 5, a preferred control procedure in the case of increasing the low pressure (maintaining the high pressure) will be described. To raise the lower pressure than the current, the target low pressure LP_t is set higher than the current low pressure. Then, because the current low pressure and the target low pressure are different, the “low pressure control with the expansion valve” is operated, and the expansion valve is opened more than the present (the fourth control). Then, in the initial state (L0), by the above operation, the high pressure is lowered and the low pressure is raised, and the state (L1) is obtained. The low pressure was higher as desired, but the condensation temperature was lower than the target condensation temperature (HP_t) due to the high pressure drop. That is, the high pressure deviated from the target value (HP_t).

Therefore, in order to maintain (achieve) the target high pressure (HP_t), the “high pressure control with the refrigerant (charge amount) control means” is operated. That is, since the lowered high pressure must be raised to the target high pressure HP_t, the refrigerant is charged in the circuit (first control). Then, in the state L1, both the high pressure and the low pressure rise by the above operation, and the state L2 is established. As a result, the high pressure is maintained at the same value as the initial state (L0), and the low pressure is brought closer to the target low pressure (LP_t).

It has been described that the control procedure 100 is "the evaporation temperature can be increased while maintaining the condensation temperature" by using the first control (1) and the fourth control (4) in the first embodiment. And in the fifth embodiment, if the target low pressure LP_t is set higher than the current low pressure, the fourth control 4 to open the expansion valve further operates, and the first control 1 for charging the refrigerant to the circuit operates. I explained that it is possible. Accordingly, the control procedure 100 may be referred to as “control for increasing the evaporation temperature while maintaining the condensation temperature” in the present invention.

Hereinafter, with reference to the control procedure 150 of FIG. 5, a preferred control procedure in the case of lowering the low pressure (maintaining the high pressure) will be described. To lower the pressure lower than the current, the target low pressure LP_t is set lower than the current low pressure. Then, because the current low pressure and the target low pressure are different, the “low pressure control with the expansion valve” is operated, and the expansion valve is closed more than the current (third control). Then, in the initial state (L5), by the above operation, the high pressure rises and the low pressure falls, and the state becomes the state L6. As desired, the low pressure was lowered, but the high pressure increased and the condensing temperature was higher than the target condensing temperature (HP_t). That is, the high pressure deviated from the target value (HP_t).

Therefore, in order to maintain (achieve) the target high pressure, the “high pressure control with the refrigerant (charge amount) control means” is operated. That is, the refrigerant is recovered from the circuit (second control) because the increased high pressure must be lowered to the target high pressure HP_t. Then, in the state L6, both the high pressure and the low pressure are lowered by the above operation, and the state L7 is reached. Thus, the high pressure is maintained at the same value as the initial state (L5), and the low pressure is brought closer to the target low pressure (LP_t).

It has been described that the control procedure 150 is "the evaporation temperature can be lowered while maintaining the condensation temperature" by using the second control (2) and the third control (3) in the first embodiment. And in the fifth embodiment, if the target low pressure (LP_t) is set lower than the current low pressure, the third control (3) in which the expansion valve is further closed is operated, and the second control (2) for recovering the refrigerant from the circuit is operated. Explained. Accordingly, the control procedure 150 may be referred to as “control to lower the evaporation temperature while maintaining the condensation temperature” in the present invention.

Hereinafter, with reference to the control procedure 200 of FIG. 5, a preferred control procedure in the case of increasing the high pressure (maintaining the low pressure) will be described. To increase the high pressure than the current one, the target high pressure HP_t is set higher than the current high pressure. Then, since the current high pressure and the target high pressure HP_t are different, in order to achieve the target high pressure HP_t, the “high pressure control with the refrigerant (charge amount) control means” is operated, and the refrigerant is charged in the circuit (first control). Then, in the initial state H0, both high and low pressures are raised by the above operation, and the state H1 is obtained. The high pressure became higher as desired, but the low pressure increased, so the evaporation temperature became higher than the target evaporation temperature (LP_t). That is, the low pressure deviated from the target value LP_t.

Therefore, in order to maintain (achieve) the target low pressure, the “low pressure control with the expansion valve” is operated. In other words, since the increased low pressure must be lowered to the target low pressure LP_t, the expansion valve is further closed (third control). Then, in the state H1, by the above operation, the high pressure rises and the low pressure falls, and the state H2 becomes. That is, the low pressure is maintained at the same value as the initial state (H0), and the high pressure is brought closer to the target high pressure (HP_t).

It has been described that the control procedure 200 is "the condensation temperature can be increased while maintaining the evaporation temperature" by using the first control (1) and the third control (3) in the first embodiment. And in the fifth embodiment, if the target high pressure (HP_t) is set higher than the current high pressure, the first control (1) for charging the refrigerant into the circuit operates, and the third control (3) in which the expansion valve is further closed is operated. Explained. Accordingly, the control procedure 200 may be referred to as “control for increasing the condensation temperature while maintaining the evaporation temperature” in the present invention.

Hereinafter, with reference to the control procedure 250 of FIG. 5, a preferred control procedure in the case of lowering the high pressure (maintaining the low pressure) will be described. To lower the high pressure than the current one, the target high pressure HP_t is set lower than the current high pressure. Then, since the current high pressure and the target high pressure (HP_t) are different, in order to achieve the target high pressure (HP_t), the “high pressure control with the refrigerant (charge amount) control means” is operated to recover the refrigerant from the circuit (second control). Then, in the initial state H5, both the high and low pressures are lowered by the above operation, and the state H6 is obtained. The high pressure became lower as desired, but the low pressure also went down, so the evaporation temperature was lower than the target evaporation temperature (LP_t). That is, the low pressure deviated from the target value LP_t.

Therefore, in order to maintain (achieve) the target low pressure, the “low pressure control with the expansion valve” is operated. That is, since the lowered low pressure must be raised to the target low pressure LP_t, the expansion valve is further opened (the fourth control). Then, in the state H6, by the above operation, the high pressure decreases and the low pressure rises, resulting in a state H7. That is, the low pressure is maintained at the same value as the initial state (H5), and the high pressure is brought closer to the target high pressure (HP_t).

It has been described that the control procedure 250 is "the condensation temperature can be lowered while maintaining the evaporation temperature" by using the second control (2) and the fourth control (4) in the first embodiment. And in the fifth embodiment, if the target high pressure HP_t is set lower than the current high pressure, the second control 2 for recovering the refrigerant from the circuit operates, and the fourth control 4 for further opening the expansion valve is operated. Explained. Accordingly, the control procedure 250 may be referred to as “control to lower the condensation temperature while maintaining the evaporation temperature” in the present invention.

Hereinafter, an example of a method for controlling the cooling mode of the heat pump 1100 suitable for the present invention will be described with reference to FIG. 11. 11, the heat pump 1100 includes a compressor (C), a condenser (HEX_C), a liquid refrigerant storage space (RS11), an expansion valve (EXV), and an evaporator (HEX_E) connected in the order described above to form a refrigerant circulation circuit. Achieve. It is preferable that the heat pump 1100 further includes a sensor PT for measuring temperature and pressure at the outlet of the condenser HEX_C, a condenser fan FN_C, and an evaporator fan FN_E. Further, it is preferable that the heat pump 1100 further includes a controller, and the controller controls the components to adjust the performance of each component. In the following description, if there are descriptions such as "controlled", "controlled", and "controlled", it should be noted that "controller provides control values so that the above description is made".

Refrigerant is charged into the heat pump (high condensation temperature) so that the cooling mode operates even at the worst high temperature. Therefore, under other conditions (eg, low load condition), excess refrigerant is present in the system, which lowers the efficiency of the heat pump. One of the ways to solve this is to make the excess refrigerant into a liquid rather than a gas, thereby minimizing the effect of the excess refrigerant on the pressure.

For example, in a heat pump using a thermal expansion valve (TXV), if the system is stabilized under a specific load, the amount of refrigerant in the low pressure section will be almost constant. (It is natural that the electronic expansion valve can be used to control the low pressure and the refrigerant flow rate.) And, the rest of the charged refrigerant are all present in the high-pressure section. When a certain amount of refrigerant coexists as a gas and a liquid in the high-pressure part, the pressure changes according to the amount of gas. That is, if you want to lower the high pressure more than the present, the high-pressure gas refrigerant becomes a liquid refrigerant, so that the gas refrigerant is less than the present. In this embodiment, the liquid refrigerant is stored in the refrigerant storage space RS11. For reference, the refrigerant storage space RS11 may be implemented integrally with the condenser HEX_C. In addition, it is natural that the liquid refrigerant may be stored in the refrigerant storage space illustrated in the prior patent document.

In this embodiment, the controller performs control to operate as follows.

1) Variable capacity compressor: Compressor C compresses the set amount of refrigerant per unit time. For example, in the case of the inverter compressor C, it operates at a set frequency corresponding to the size of the load. In other words, the set frequency is calculated and calculated from the difference between the actual temperature and the target temperature inside the space to be cooled. If the low pressure and superheat degree are kept constant, the amount of refrigerant compressed by the inverter compressor C per unit time will be constant for each frequency. Hereinafter, for convenience of explanation, it will be described using an inverter compressor (C). At this time, it should be noted that the frequency of the inverter compressor represents the amount of refrigerant compression per unit time. (Hereinafter, “refrigerant compression amount control per unit time”)

2) Condenser: The condenser fan (FN_C) operates so that the subcooling degree (SC) of the refrigerant measured at the outlet of the condenser (HEX_C) becomes the target subcooling degree (SC_t). (Hereinafter, “subcooling control with a condenser fan”)

3) Expansion valve: The expansion valve (EXV) is operated so that the inlet pressure (evaporator outlet pressure) of the compressor (C) becomes the target pressure (LP_t). More specifically, a controller (not shown) controls the inlet pressure of the compressor C (evaporator outlet pressure) by adjusting the opening degree of the expansion valve EXV. To this end, the expansion valve EXV is preferably an electronic expansion valve EEV. When the expansion valve (EEV) is opened more than the current one, more refrigerant than the current one goes down to the low pressure and the low pressure rises. On the contrary, if the expansion valve (EEV) is closed more than the present, less refrigerant than the present goes down to the low pressure and the low pressure goes down. (Hereinafter “low pressure control with expansion valve”)

When looking at the fluctuation of high pressure and low pressure according to refrigerant charging and recovery in the thermal responsive expansion valve (TXV), the high pressure fluctuation is much larger than the low pressure fluctuation. If the amount of refrigerant is charged so that the high pressure can generate more than a desirable value, and if the high pressure and superheat are controlled to an appropriate value, the low pressure for each load size will have an almost constant value (design target low pressure). Therefore, it is natural that this case can be referred to as “low pressure control with an expansion valve”.

4) Evaporator: In the case of the electronic expansion valve (EEV), the evaporator fan (FN_E) operates so that the superheat (SH) of the refrigerant measured at the outlet of the evaporator (HEX_E) becomes the target superheat (SH_t). (Hereinafter, “superheat control with an evaporator fan”)

When the expansion valve is thermally responsive (TXV), the speed of the evaporator fan is controlled in response to the load size as in the prior art (hereinafter, “controlling the evaporator fan speed by the load size”).

5) High pressure control: The refrigerant (charge amount) control means is operated so that the outlet pressure (condenser inlet pressure) of the compressor C becomes the target pressure (HP_t). To achieve this, the amount of refrigerant in the gaseous state at high pressure is adjusted to be a liquid refrigerant, and the refrigerant in the liquid state is stored in the storage space RS11.

In order to lower the high pressure, the gas refrigerant at the high pressure must be reduced more than the present. For this purpose, it is desirable to operate the condenser fan (FN_C) at a higher speed than the current one. Then, the amount of refrigerant converted from gas to liquid is increased (more specifically, the amount of refrigerant compressed by the compressor is converted to liquid more than that), and the degree of subcooling is also increased. In addition, the liquid refrigerant will be (preferably) stored (ie, recovered to the storage space) in the liquid refrigerant storage space RS11 existing between the condenser outlet and the expansion valve. In other words, the refrigerant is recovered from the circuit to the storage space RS11, thereby lowering the high pressure.

On the other hand, when the target subcooling degree is set to be larger than the present, the condenser fan FN_C operates at a faster speed than the present, and the amount of refrigerant converted from gas to liquid increases. The converted liquid refrigerant is (preferably) stored in the storage space RS11 (ie, recovered to the storage space), and the high pressure will be lowered. Hereinafter, when the refrigerant is recovered to the storage space and the high pressure is lowered, the target subcooling level is referred to as “recovery target subcooling level (SC_tr)”.

In order to increase the high pressure, the gas refrigerant at the high pressure must be increased more than the present. For this purpose, it is desirable to operate the condenser fan (FN_C) at a slower speed than it is today. Then, the amount of refrigerant converted from gas to liquid is reduced (more specifically, the amount of refrigerant compressed by the compressor is converted to liquid less than that), and the degree of subcooling is also reduced. In addition, since the amount of refrigerant changed to liquid is smaller than before the fan speed FN_C was adjusted, the amount of refrigerant stored in the liquid refrigerant storage space RS11 is also reduced. In other words, the refrigerant is charged into the circuit in the storage space RS11, so that the high pressure increases. On the other hand, if the target subcooling degree is set to be smaller than the present, the condenser fan FN_C operates at a slower speed than the present, and the amount of refrigerant converted from gas to liquid decreases, thereby increasing the high pressure. In addition, since the amount of refrigerant changed to liquid is smaller than before the fan speed FN_C is adjusted, the amount of refrigerant stored in the liquid refrigerant storage space RS11 is also reduced. Hereinafter, when the high pressure is increased by charging the refrigerant from the storage space to the circuit, the target subcooling level is referred to as “charging target subcooling level (SC_tc)”.

In summary, when you want to increase the high pressure, it is desirable to set the degree of subcooling to “target charge level of subcooling (SC_tc). And when you want to lower the high pressure, it is desirable to set the subcooling degree as “recovery target subcooling degree (SC_tr). In other words, if the current high pressure is higher than the target high pressure, it is preferable to make the target subcooling degree (SC_t) larger than the present, and if the current high pressure is lower than the target high pressure, it is preferable to make the target subcooling degree (SC_t) lower than the current one. The charging target subcooling level (SC_tc), recovery target subcooling level (SC_tr) and target subcooling level (SC_t) are used to achieve the target high pressure through a number of preceding experiments in various environments (eg, outside temperature, load, high pressure, low pressure...) ) Can be obtained, and it is natural that the controller can use the obtained value. [Hereinafter, “high pressure control with refrigerant (charge amount) control means”]

6) Target condensation temperature setting: It is preferable that the target high pressure (HP_t) [condensation temperature (Tc)] is higher than the outside air temperature by a predetermined value (c1) by referring to the outside air temperature (Ta). It is also desirable to set it with reference to the outside temperature and the load size. If this is expressed as a formula, an example can be given as follows.

Tc = Ta + c1

Example) c1=10.0, Tc = Ta + 10.0 regardless of the load size

Tc = Ta + c1 + c2 x load / rated load

Example) If c1=10.0, c2=1.0, rated load=10.0 kW, load= 2kW, then Tc=Ta + 10.2 ℃, if load= 4kW, Tc=Ta + 10.4℃

On the other hand, it is natural that the target condensation temperature can be obtained through a number of preceding experiments in various environments (eg, outside air temperature, load, low pressure...), and that the obtained value can be used by the controller.

7) Target evaporation temperature setting: For air conditioners, it is desirable to set the value between 0 and 15 ℃. It is preferable that the betting temperature is higher by a predetermined value e1 than the betting temperature, referring to the betting temperature Tin. It is also desirable to set with reference to the inner air temperature (Tin) and the load size. If this is expressed as a formula, an example can be given as follows. It is natural that it is desirable to lower the target evaporation temperature when the cooling load is large.

Te = Tin-e1

Example) e1=15.0, Te = Tin-15.0 regardless of the load size

Te = Tin-(e1 + e2 x load / rated load)

Example) e1=10.0, e2=10.0, rated load=10.0 kW

If load= 3kW, Te=Tin-13.0 ℃

If load= 9kW, Te=Tin-19.0 ℃

On the other hand, it is natural that the target evaporation temperature can be obtained through a number of preceding experiments in various environments (eg, internal air temperature, load, high pressure...), and that the obtained value can be used by the controller.

It is natural that the control procedures (100), (150), (200) and (250) of Fig. 5 can be performed by the operation of the controller described in this embodiment. Since the detailed description of the control procedures has been made in Embodiment 5, the description is omitted for convenience.

On the other hand, in the case of a thermal expansion valve (TXV), it is not possible to adjust the low pressure by varying the low pressure, but it is natural that the high pressure can be adjusted by varying the control sequence 200 and 250. At this time, since the expansion valve TXV cannot be directly controlled by the controller, it is natural that only the charging and recovery of the refrigerant remain in the control procedures 200 and 250 that the controller can directly control. Therefore, in the present specification, even if there is no separate description, in the case of the thermal expansion valve (TXV), the control procedure 200 should be interpreted as charging of the refrigerant and the recovery of the refrigerant in the control procedure 250. At this time, it is preferable that the speed of the evaporator fan FN_E is adjusted according to the size of the load.

The preferred embodiment of the present invention has been described in detail above.

In the present invention, the case of operating the heat pump in the cooling mode has been described in detail, but it is natural that the concept of the present invention can be used even in the heating mode. In the embodiment of the present invention, it is described as one compressor, an outdoor heat exchanger, and an indoor heat exchanger, respectively, but it is natural to those skilled in the art that the present invention may be implemented in a plurality.

In this specification, it has been described that heat exchange with air is performed, but it is natural for those skilled in the art that heat exchange with liquid can be performed. Therefore, in the present invention, air should be interpreted as a "fluid" containing water. In addition, it is natural that the fan for supplying the fluid to the heat exchanger includes a pump for flowing the liquid to the heat exchanger.

In a car, even though the outside temperature is low (the indoor temperature is high due to the greenhouse effect by closing the window, or because dew has formed on the window due to rain..), there are many cases where the air conditioner needs to be operated. And, the inverter compressor (also known as variable capacity compressor) has a slightly different high/low pressure when it is a high load and a high/low pressure when it is a low load. It is natural that the heat pump heat exchanger according to the present invention can perform heat exchange with minimum power consumption in any case.

In a conventional air conditioner without a refrigerant (charging amount) control means, when the outside air temperature is 35°C, the condenser temperature is approximately 60°C, and when the outside air temperature is 25°C, the condenser temperature is approximately 50°C. And when the cooling load amount was determined, the condensation temperature of the condenser and the evaporation temperature of the evaporator could not be adjusted. With the heat pump of the present invention, performance (COP) is improved by about 30% when the evaporator temperature is set to 0℃ in the vehicle air conditioner, the superheat and subcooling degrees are set to 5℃, and the condenser temperature is lowered from 60℃ to 50℃. . This means that the air conditioner efficiency can be improved by about 30% in the SC03 mode (outside air 35℃), which is a measurement condition for fuel efficiency of automobile air conditioners in the US. And, when the condenser temperature is lowered from 50℃ to 40℃, the performance (COP) is improved by about 33%. This means that the air conditioner efficiency can be improved by about 33% in AC17 mode (25℃ outside air), which is the measurement condition of CO2 generation by automobile air conditioners in the United States.

As described above, the preferred embodiments of the present invention have been described, but these are only examples, and those of ordinary skill in the art will understand that various modified embodiments are possible therefrom. Therefore, the embodiments of the present invention disclosed in the present specification and drawings are merely provided for specific examples to easily explain the technical content of the present invention and to aid understanding of the present invention, and are not intended to limit the scope of the present invention.

According to the heat pump control method of the present invention as described above, since it is possible to increase the performance (COP) of the heat pump by preventing the gap between the high pressure and the low pressure from increasing during the operation of the heat pump, industrial use is very high.

And, in a simple concept, pressure can be interpreted as "how many things are there". The air conditioner must be operated even in the worst conditions (eg 45 ℃). So, refrigerant is charged to the heat pump based on the worst condition. Then, in a standard load condition (eg, 25° C.) and a low load condition (eg, 21° C.), the refrigerant is operated in an overcharged state, resulting in low energy efficiency. If the condensation temperature is controlled (by adjusting the amount of refrigerant) in the method suggested by the present invention, a heat pump with higher efficiency than before can be provided.

In particular, in the case of automobiles, the fuel economy of the air conditioner operating vehicle is improved, and the amount of greenhouse gas (CO ₂ ) generated by the air conditioner is reduced, so the possibility of industrial use is very high.

HEX_C condenser
HEX_E evaporator
EXV, EXV1, EXV2 expansion valve
C compressor
RS1, RS2, RS3 refrigerant storage tank
FN_C condenser fan
FN_E evaporator fan
vvc refrigerant charging valve
vvd refrigerant recovery valve

Claims (17)

A circuit including a compressor, a condenser, an expansion valve (hereinafter, "first expansion valve") and an evaporator is connected through a sealed refrigerant line, and the condenser fan, the evaporator fan, and the circuit are charged with refrigerant or refrigerant is recovered from the circuit. In the control method of a heat pump comprising a refrigerant (charge amount) control means (hereinafter, "second expansion valve"),
The second expansion valve comprises a recovery valve for recovering the refrigerant from the circuit, a storage space for storing the refrigerant, and a charging valve for charging the refrigerant to the circuit in series in the order,
The second expansion valve is installed between the inlet of the first expansion valve and the low pressure line,
Setting a target condensation temperature;
When the condensation temperature is lower than the target condensation temperature, the refrigerant control means charges the circuit with a refrigerant;
When the condensation temperature is higher than the target condensation temperature, the refrigerant refrigerant control means recovers the refrigerant from the circuit; Including,
A certain amount of refrigerant passes through the second expansion valve in daily operation; Heat pump control method The method of claim 1,
When the power required to control the second expansion valve is started,
Emptying the refrigerant in the storage space by controlling the opening degree of the recovery valve (vvd) to be smaller than that of the charging valve (vvc); After performing
Reducing the opening degree of the charging valve vvc when the set initialization step time (s_init) elapses or the high pressure is higher than the target high pressure; Heat pump control method further comprising a. The method of claim 1,
In the refrigerant charging step and the recovery step, one of the charging valve (vvc) and the recovery valve (vvd) is a control for fixing the opening degree and adjusting the other valve; Heat pump control method further comprising a. The method of claim 1,
The first expansion valve may be any one of a capillary tube, a thermal expansion valve (TXV), a pressure sensitive expansion valve (PXV), or an electronic expansion valve (EEV); In heat pump control method. The method of claim 1,
The charging valve (vvc) and the recovery valve (vvd) include an orifice for bypassing the refrigerant; Heat pump control method. A refrigerant line with a closed circuit including a compressor, a condenser, an expansion valve, and an evaporator.
Is connected through a condenser fan, an evaporator fan, and a refrigerant in the circuit or the circuit
Including a refrigerant (charge amount) control means (with a refrigerant storage space) for recovering the refrigerant from
In the cooling mode control method of the heat pump,
"Control to increase the condensation temperature while maintaining the evaporation temperature";
"Control to lower the condensation temperature while maintaining the evaporation temperature";
While maintaining the same heat exchange amount (Q = c·m·dT) of the condenser, the condenser fan power consumption is increased (i.e., the m is increased), and the compressor power consumption is decreased [more specifically, the condenser A calculation step of lowering the internal pressure (ie, condensing temperature) to reduce the dT)] and lowering power consumption of the heat pump; And
Determining the minimum power consumption of the heat pump by performing the calculation if the condenser fan is driven below the maximum rated power consumption; Heat pump control method comprising a. A refrigerant line with a closed circuit including a compressor, a condenser, an expansion valve, and an evaporator.
Is connected through a condenser fan, an evaporator fan, and a refrigerant charge in the circuit or the circuit
Including a refrigerant (charge amount) control means (with a refrigerant storage space) for recovering the refrigerant from
Is in the heat pump,
"Control to increase the condensation temperature while maintaining the evaporation temperature";
"Control to lower the condensation temperature while maintaining the evaporation temperature";
"Control to increase the evaporation temperature while maintaining the condensation temperature"; And
"Control to lower the evaporation temperature while maintaining the condensation temperature";
Heat pump comprising a. A refrigerant line with a closed circuit including a compressor, a condenser, an expansion valve, and an evaporator.
Is connected through a condenser fan, an evaporator fan, and a refrigerant charge in the circuit or the circuit
Including a refrigerant (charge amount) control means (with a refrigerant storage space) for recovering the refrigerant from
In the control method of the heat pump,
While maintaining the same amount of heat exchange (Q = c·m·dT) of the “heat exchanger”, the “heat exchanger” fan power consumption is increased (ie, m is increased), and the compressor power consumption is lowered to [more] Specifically, the dT is reduced by adjusting the pressure inside the heat exchanger (ie, the boiling point of the refrigerant)]] In the calculation of lowering the power consumption of the heat pump, the maximum power consumption of the outdoor heat exchanger fan is the rated fan Heat pump control method, which is the maximum power consumption. The method according to any one of claims 6 to 8,
Setting a target condensation temperature; And
Setting a target evaporation temperature; Heat pump control method further comprising a. The method of claim 6,
The heat pump control method in which the maximum amount of refrigerant stored in the refrigerant storage space is less than 1/2 of the total amount of refrigerant present in the heat pump. The method according to any one of claims 6 to 8,
When lowering the condensing temperature further, first, the power consumption of the condenser fan is further increased to increase the degree of subcooling, and the control means recovers the refrigerant from the circuit; and,
When the evaporation temperature is further increased, first, the power consumption of the evaporator fan is further increased to increase the superheat degree, and the control means charges the refrigerant into the circuit; Heat pump control method. The method according to any one of claims 6 to 8,
A heat pump control method in which some of the refrigerant circulating in the circuit passes through the storage tank in normal operation. The method according to any one of claims 6 to 8,
The refrigerant control means includes a function of separating a gas refrigerant from a liquid refrigerant;
Heat pump control method for supplying the separated gas refrigerant to a compressor. The method according to any one of claims 6 to 8,
The refrigerant control means comprises a return valve for recovering the refrigerant from the circuit, a storage space for storing the refrigerant, and a charging valve for charging the refrigerant to the circuit in series in the order; Become,
The refrigerant control means is installed between the outlet of the condenser and the low pressure line; Heat pump control method. A circuit including a variable capacity compressor, a condenser, an electronic expansion valve, and an evaporator is connected through a sealed refrigerant line, and a condenser fan, an evaporator fan, and a refrigerant (charging amount) for charging refrigerant to the circuit or recovering refrigerant from the circuit are adjusted. In the heat pump comprising a means and a controller,
Setting a target high pressure (HP_t);
Setting a target low pressure (LP_t);
Setting a target subcooling degree (SC_t); And
Including; setting a target superheat degree (SH_t)
The controller controls the compressor to compress the amount of refrigerant per unit time in response to the size of the load (e.g., in the case of an inverter compressor, it operates at a frequency set corresponding to the size of the load),
In addition, the controller controls the speed of the condenser fan so that the degree of subcooling at the outlet of the condenser is the target subcooling,
In addition, the controller controls the expansion valve to make the compressor inlet pressure (evaporator outlet pressure) a target low pressure (LP_t),
In addition, the controller controls the speed of the evaporator fan so that the superheat degree at the evaporator outlet makes the target superheat degree,
In addition, the controller is a heat pump, characterized in that for adjusting the refrigerant (charging amount) adjusting means for causing the outlet pressure (condenser inlet pressure) of the compressor to become a target pressure (HP_t). A circuit including a variable-capacity compressor, a condenser, an expansion valve, and an evaporator is connected through a sealed refrigerant line, and a condenser fan, an evaporator fan, a refrigerant (charge amount) control means for charging the refrigerant to the circuit or recovering the refrigerant from the circuit. And in the heat pump comprising a controller,
Setting a target high pressure [condensation temperature (HP_t)]; And
Setting a target subcooling degree (SC_t); Including,
The controller controls the compressor to compress the amount of refrigerant per unit time in response to the size of the load (e.g., in the case of an inverter compressor, it operates at a frequency set corresponding to the size of the load),
In addition, the controller controls the speed of the condenser fan so that the degree of subcooling at the outlet of the condenser is the target subcooling,
In addition, the controller is a heat pump, characterized in that for adjusting the refrigerant (charging amount) adjusting means for causing the outlet pressure (condenser inlet pressure) of the compressor to become a target pressure (HP_t). The method of claim 16,
Setting a target low pressure [evaporation temperature (LP_t)]; And
Setting a target superheat degree (SH_t); Including more,
The expansion valve is an electronic expansion valve (EEV);
The controller controls the expansion valve to make the compressor inlet pressure (evaporator outlet pressure) a target low pressure (LP_t),
In addition, the controller is a heat pump, characterized in that for controlling the evaporator fan speed so that the superheat degree at the evaporator outlet makes the target superheat degree.

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