KR20190005475A - A high performance heat pump having variable capacity refrigerant storage means - Google Patents

Abstract

The present invention relates to a heat pump and, more specifically, relates to a heat pump which has a variable capacity refrigerant storage means to individually control entrance pressure and exit pressure of a compressor at the same time. According to the present invention, the heat pump using refrigerant comprises a compressor, a condenser, an expansion valve, and an evaporator, wherein refrigerant is circulated through a sealed refrigerant line. The heat pump has a refrigerant storage means that is connected to the refrigerant line, stores a portion of the refrigerant, and controls a circulation amount of the refrigerant circulating in the refrigerant line. The exit pressure of the compressor is controlled by the circulation amount of the refrigerant, wherein the circulation amount is controlled by the refrigerant storage means.

Description

 A high performance heat pump having variable capacity refrigerant storage means,

The present invention relates to a heat pump. And more particularly, to a heat pump capable of individually controlling the inlet pressure and the outlet pressure of the compressor at the same time.

A heat pump is a device that transfers heat from a heat source to a destination called a "heater sink". A heat pump absorbs heat in a cold space and releases heat in a warm space. That is, the heat pump transmits thermal energy in the opposite direction of the natural heat transfer direction. To do this, the heat pump uses a small amount of external energy to transfer energy from the heat source to the heat sink.

Air conditioners and refrigerators are typical examples of heat pumps. Also, a heating ventilation and air conditioning (HVAC) system for heating or cooling a certain space is also a heat pump. The equipment using the heat pump includes a water purifier, a dryer, a washing machine, and a vending machine which provide cold / hot water.

Hereinafter, a heat pump (vapor compression type) operating in a cooling mode (refrigerant circulating in a counterclockwise direction in FIG. 1) will be described with reference to FIGS. 1 and 2. FIG.

In order to perform the vapor compression refrigeration cycle, the compressor (C) compresses the gaseous refrigerant.

The compressed high-temperature and high-pressure refrigerant vapor discards heat to the outside of the relatively low temperature in an external heat exchanger (HXO) serving as a condenser. At this time, the gaseous refrigerant discharges latent heat to make a phase transition to a liquid state. In the ideal heat pump, only the phase change occurs in the condenser, so the temperature and pressure of the refrigerant do not change.

The liquid refrigerant exiting the external heat exchanger (HXO) is decompressed while passing through the expansion valve (EV). In an ideal heat pump, the inlet enthalpy and outlet enthalpy of the expansion valve (EV) are the same, and the temperature of the decompressed refrigerant decreases to have the same enthalpy.

The low-temperature liquid refrigerant passes through the internal heat exchanger (HXI), which functions as an evaporator, and absorbs heat to become a gas.

The gas refrigerant passing through the evaporator enters the compressor (C) again and repeats the above cycle.

Fig. 2 is an example of a vehicle air conditioner in which the condenser is designed to be 60 DEG C and the evaporator is designed to be 0 DEG C in the p-h line. Assuming that the outside air temperature is 30 ° C and the cooling setting temperature is 20 ° C, the gas refrigerant at 60 ° C in the external heat exchanger (HXO) as the condenser releases heat to the outdoor at 30 ° C to become the liquid refrigerant at 60 ° C. In the internal heat exchanger (HXI), which is an evaporator, the 0 ° C liquid refrigerant becomes 0 ° C gas refrigerant (absorbs heat from the room air above the set temperature). For an ideal heat pump it is assumed that there is no change in pressure in the condenser, evaporator and piping. Therefore, the compressor inlet pressure and the outlet pressure may be regarded as the refrigerant temperature.

The problems of the prior art will be described below.

Problem 1) There is a problem that the inlet pressure and the outlet pressure of the compressor (C) can not be individually adjusted simultaneously. That is, when the compressor or the expansion valve is adjusted to lower the inlet pressure of the compressor (C), the outlet pressure is increased. On the other hand, increasing the inlet pressure of the compressor (C) lowers the outlet pressure. Accordingly, when the outside air temperature is changed, the compressor outlet pressure (refrigerant temperature) having a predetermined value higher than the outside air and the compressor inlet pressure (refrigerant temperature) having a predetermined value lower than the inside air, in which heat exchange is appropriately performed in the heat exchanger, There is a problem of energy consumption.

Problem 2) Generally, the automobile mixes with the low-temperature air heat exchanged in the evaporator to achieve the set cooling temperature by using the engine heat or the separate heater to make the high temperature air in order to set the set temperature. Therefore, energy is wasted more than when air is not mixed.

Application No. KR 10-2006-0107825 Application No. KR 10-2010-0038007 Application No. KR 10-2013-0084665 (US 9,372,015 B2) Application No. KR 10-2014-0008064 Application No. KR 10-2015-0157868 Application No. KR 10-2015-0060594 Application No. KR 10-2016-7026168 (US 2017/0010030 A1) Application No. KR 10-2016-7026740 (US 2016/0370044 A1) Application No. KR 10-2016-706346 (PCT / FR2014 / 052983) DE 102013003015 A1 US 2015/0323225 A1 US 2015/0266358 A1

The present invention has been made in order to solve the problems of the prior art. That is, it is an object of the present invention to provide a heat pump capable of individually controlling the inlet pressure and the outlet pressure of the compressor simultaneously.

To this end, a heat pump using a refrigerant according to the present invention is a heat pump having a compressor, a condenser, an expansion valve, and an evaporator, and circulating the refrigerant through a hermetically sealed refrigerant line. The heat pump is connected to the refrigerant line, And a refrigerant storage means for storing a portion of the refrigerant and controlling the amount of circulation of the refrigerant circulated in the refrigerant line, wherein the outlet pressure of the compressor is controlled by a circulation amount of the refrigerant controlled by the refrigerant storage means; .

At this time, the refrigerant storage means is installed between the outlet of the compressor and the expansion valve; .

The refrigerant storage means may include: a cylinder having an internal space for storing the refrigerant; An inner wall dividing one side and the other side of the inner space; And a moving means for reciprocating the inner wall in the inner space, wherein one side of the inner space has a higher density of refrigerant than the other side and a lower density of refrigerant is stored in the other side of the inner space; .

Further, the moving means may include a pump for transferring the refrigerant to one side of the internal space; .

Further, the moving means may include a piston reciprocating the inner wall; .

Also, the inlet pressure of the compressor is regulated by the expansion valve, and the inlet and outlet pressures of the compressor are individually regulated; .

The refrigerant storage means may include an internal space for storing the refrigerant; A refrigerant inflow valve disposed between the internal space and the condenser outlet (or any one of the condenser inlets); And a refrigerant outflow valve installed between the inner space and the evaporator inlet (or one of the evaporator outlets); .

A control method of a heat pump including a compressor, a condenser, an expansion valve, and an evaporator connected through a closed refrigerant line and connected to the refrigerant line to control a circulation amount of the refrigerant, Setting a temperature; Controlling the expansion valve and the evaporator to control an inlet pressure of the compressor; And controlling the amount of the refrigerant stored by the refrigerant storage means to control an outlet pressure of the compressor; .

The refrigerant storage means may be disposed between the expansion valve and the outlet of the compressor; .

The refrigerant storage means may include: a cylinder having an internal space for storing the refrigerant; An inner wall dividing one side and the other side of the inner space; And a moving means for reciprocating the inner wall in the inner space, wherein one side of the inner space has a higher density of refrigerant than the other side and a lower density of refrigerant is stored in the other side of the inner space; .

Further, the moving means may include a pump for transferring the refrigerant to one side of the internal space; .

The moving means may further comprise a piston reciprocating the inner wall; .

Further, the inlet pressure of the compressor is controlled by the expansion valve, and the inlet pressure and the outlet pressure of the compressor are individually adjusted.

The refrigerant storage means may include an internal space for storing the refrigerant; A refrigerant inflow valve disposed between the internal space and the condenser outlet (or any one of the condenser inlets); And a refrigerant outflow valve installed between the inner space and the evaporator inlet (or one of the evaporator outlets); .

According to the heat pump having the variable capacity refrigerant storage unit according to the present invention, it is possible to provide a heat pump capable of individually controlling the inlet pressure and the outlet pressure of the compressor simultaneously.

1 is an example of a conventional heat pump.
2 is an example of a ph diagram according to the prior art.
3 is an example of a heat pump according to the present invention.
4 is an example of a ph diagram according to the present invention.
5 is an example of another ph diagram according to the present invention.
6 is another example of the heat pump according to the present invention.
7 is another example of the heat pump according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same components are denoted by the same reference numerals as possible in the accompanying drawings.

In addition, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and should be construed in accordance with the technical concept of the present invention. Further, the detailed description of known configurations and functions that may be unnecessarily obscured by the gist of the present invention will be omitted.

For convenience of explanation, an ideal heat pump will be used unless otherwise specified.

A key concept of the present invention is to provide a variable displacement refrigerant storage means in a heat pump and to adjust the amount of circulating refrigerant so that the inlet and outlet pressures of the compressor can be adjusted simultaneously and individually.

Hereinafter, a preferred embodiment of the heat pump (air conditioning cooling mode) according to the present invention will be described with reference to FIG.

3a and 3b, the heat pump includes a compressor C1 for compressing refrigerant in a gaseous state; A condenser (HXO, external heat exchanger) that converts gas refrigerant of high temperature and high pressure into heat by exchanging heat; An expansion valve (EV) for expanding the refrigerant; An evaporator (HXI, internal heat exchanger) that converts the expanded refrigerant into heat by exchanging heat; And variable capacity refrigerant storage means (RS) for storing high-pressure refrigerant. 3, the variable capacity refrigerant storage device RS is disposed between the condenser (HXO) outlet and the expansion valve (EX) inlet.

3A and 3B, the compressor C1 compresses the same amount of refrigerant per unit time, and assuming that the opening degree of the expansion valve EV is the same, the outlet pressure of the compressor C1 is supplied to the refrigerant storage means RS It is determined by the amount of refrigerant stored. That is, if a small amount of refrigerant is stored in the variable capacity refrigerant storage means RS as shown in FIG. 3A, the outlet pressure of the compressor C1 is increased. When a large amount of refrigerant is stored as shown in FIG. 3B, The outlet pressure is lowered.

In summary, the outlet pressure of the compressor (C1) is controlled by the amount of refrigerant stored in the variable capacity refrigerant storage means (RS) storing the high pressure refrigerant. It is to be understood that the refrigerant storage means RS may be disposed at any position between the high pressure line, that is, between the outlet of the compressor C1 and the inlet of the expansion valve EX. The refrigerant storage means RS may be disposed inside the compressor or attached to a condenser as a heat exchanger to form a body.

Hereinafter, a method of adjusting the inlet pressure of the compressor C1 will be described.

The inlet pressure of the compressor (C1) is regulated by the operation of the expansion valve (EX) or the compressor (C1). More specifically, when the opening degree of the expansion valve EX is reduced, the amount of refrigerant passing through the expansion valve is reduced, so that the inlet pressure of the compressor C1 is lowered. Increasing the degree of opening also increases the inlet pressure of the compressor C1.

When the amount of refrigerant compressed by the compressor C1 per unit time increases, the inlet pressure of the compressor C1 decreases. Conversely, when the amount of refrigerant compressed per unit time decreases, the inlet pressure of the compressor C1 increases.

As described above, in the heat pump, a method of adjusting the inlet pressure and the outlet pressure of the compressor individually by adjusting the amount of the circulating refrigerant and having variable-capacity refrigerant storage means has been described in detail.

Hereinafter, an embodiment of the present invention (an air conditioning mode) will be described with reference to FIG.

The refrigeration cycles (1) - (2) - (3) - (4) are ph diagrams according to the prior art, and the refrigeration cycles (1a) - (2) - (3) - (4a) It is leading.

When the opening degree of the expansion valve is increased in the conventional heat pump, the inlet pressure of the compressor becomes high. That is, the refrigeration cycle (4) - (1) becomes the refrigeration cycle (4a) - (1a). In Fig. 4, the evaporator temperature rises from 0 占 폚 to 10 占 폚. This is the same as the conventional technique.

 In the prior art, when the opening degree of the expansion valve EX is increased, the refrigerant cycle (2) - (3) is not maintained because the compressor outlet pressure is lowered. (As will be described in more detail below, if the compressor outlet pressure is lower than a predetermined value, the temperature difference between the condenser and the outside air is lowered to lower the heat exchange efficiency and the gas refrigerant may be contained in the refrigerant compressed by the liquid. Lower.)

On the other hand, in the present invention, it is possible to reduce the amount of refrigerant stored in the variable capacity refrigerant storage means (RS), thereby increasing the amount of refrigerant circulated in the refrigeration cycle. That is, if the amount of refrigerant in the high-pressure line through which the refrigerant circulates is increased, the outlet pressure of the compressor (C1) is increased, thereby maintaining the refrigerating cycles (2) - (3). Consequently, by changing the amount of refrigerant stored in the variable capacity refrigerant storage means (disposed in the high pressure line), the compressor outlet pressure can be adjusted.

As described above, the method of individually controlling the compressor inlet pressure and the compressor outlet pressure simultaneously has been described. In Fig. 4, the refrigeration cycles (2) - (3) are determined by the outlet pressure of the compressor (C1), and the refrigeration cycles (4a) - (1a) are determined by the inlet pressure of the compressor (C1).

Since the pressure of the refrigerant and the saturated vapor temperature of the refrigerant are proportional, the outlet pressure of the compressor (C1) in the p-h diagram represents the condenser temperature. (It is expressed as "representative" because the actual depressurization of the heat pump is not a isothermal isothermal phase transition but a depressurization depressurization phase.) Therefore, the compressor C1 is controlled so that the condenser temperature becomes a predetermined higher value ), The energy consumed by the compressor can be reduced.

5, the refrigeration cycle (1b) - (2b) - (3b) - (4b) according to the present invention sets the cooling set temperature to 25 ° C and the temperature difference suitable for heat exchange to 15 ° C when the outside air temperature is 35 ° C And it is assumed that the superheating degree and the supercooling degree are appropriately controlled.

Compared with the conventional refrigeration cycles (1) - (2) - (3) - (4), the work performed by the compressor (heat energy) decreased from (1) - (2) to (1b) - , The heat energy exchanged by the evaporator increased from (4) - (1) to (4b) - (1b). On the other hand, the heat energy exchanged by the condenser increased from (2) - (3) to (2b) - (3b).

5, when the enthalpy decreased in the compressor is equal to the enthalpy increased in the condenser, the enthalpy increases in the evaporator, so that the coefficient of performance of the heat pump according to the present invention is improved (fuel economy is improved in the case of a vehicle). Particularly, when the heat pump is operated in the cooling mode in the vehicle, the cooling set temperature can be achieved without using a separate heating device, so that the fuel economy of the vehicle is further improved.

5, when the superheat degree and the subcooling degree are respectively 5 ° C, the conventional refrigeration cycles (1) - (2) - (3) - (4) The coefficient is 2.25, and the performance coefficient of the refrigeration cycles (1b) - (2b) - (3b) - (4b) according to the present invention is 3.97. Therefore, the performance coefficient is improved by 76% (= 3.97 / 2.25 * 100) from the conventional one.

Hereinafter, an embodiment of the present invention (an air conditioner cooling mode) will be described with reference to FIG.

Referring to FIG. 6, the structure of the heat pump includes a compressor (C1) for compressing the gaseous refrigerant; By changing the circulation direction of the refrigerant, the four sides (V4c); A condenser (HXO, external heat exchanger) that converts gas refrigerant of high temperature and high pressure into heat by exchanging heat; An expansion valve (EV) for expanding the refrigerant; An evaporator (HXI, internal heat exchanger) that converts the expanded refrigerant into heat by exchanging heat; And variable capacity refrigerant storage means (RS1) and variable capacity refrigerant storage means (RS2) provided in a high pressure line through which high pressure refrigerant flows.

The variable capacity refrigerant storage means RS1 includes a chamber PR1 for storing the refrigerant and a chamber PR1 for controlling the volume of the chamber Rb and the chamber Rb for storing the refrigerant. . 6, the room Ra is connected to the outlet of the condenser HXO to store the liquid refrigerant, and the room Rb is connected to the inlet of the condenser HXO to store gaseous refrigerant .

In an ideal heat pump condenser, the isothermal pressure-phase transformation occurs, so that the pressures of the chambers Ra and Rb to store the refrigerant are the same. Since the same refrigerant is stored in the two rooms, one of them is a liquid and the other is a gas, the amount of refrigerant stored in the refrigerant storage means RS1 is changed by changing the volume ratio of the two rooms by moving the piston PR1. . When the volume ratio of the two chambers Ra and Rb is changed, the volume of the actual refrigerant movement path does not change, but the amount of refrigerant existing in the volume is varied, so that the outlet pressure of the compressor C1 is varied.

   Advantageously, since the pressures of the two chambers Ra and Rb are the same, the refrigerant storage amount can be changed by moving the piston PR1 with very little energy. At this time, it is preferable that the piston is disposed in the room Ra in which the liquid refrigerant is stored, in terms of preventing refrigerant leakage. If the refrigerant storage means RS1 is installed over the high-pressure line and the low-pressure line, the piston PR1 may be moved against the pressure generated by the compressor C1, which is inefficient.

6, the variable capacity refrigerant storage means RS2 disposed at the outlet of the compressor C1 comprises a room Rc for storing refrigerant and a piston PR2 for controlling the volume of the room Rc. The refrigerant storage means RS2 stores the gaseous refrigerant, and moves the piston PR2 to change the refrigerant storage amount. At this time, since there is a high pressure between the room Rc and the outside air, relatively more energy is consumed than the refrigerant storage means RS1 to reduce the amount of stored refrigerant. On the other hand, it is natural that the variable-capacity refrigerant storage means (RS2) may be disposed inside the compressor (C1) to make an integral product.

In this embodiment, the variable capacity refrigerant storage means RS1 (having two refrigerant storage chambers) is connected to the inlet and the outlet of the condenser HXO, liquid refrigerant is stored in one storage chamber Ra, Rb) contained gaseous refrigerant. On the other hand, it is natural that the refrigerant can be stored in a variable capacity even if gas refrigerant having relatively high humidity is stored in one storage chamber (Ra) and gas refrigerant having relatively low humidity is stored in the other storage room (Rb). At this time, if the volume ratio of the two chambers (Ra) and (Rb) is changed, the volume of the actual refrigerant movement path does not change, but the amount of refrigerant existing in the volume changes. It is a matter of course that the variable-capacity refrigerant storage means can be manufactured integrally with the condenser.

In FIG. 6, the variable capacity refrigerant storage means (RS1) to (RS2) are disposed in a high pressure line through which refrigerant compressed at a high pressure flows. It is needless to say that even if the variable-capacity refrigerant storage means according to the present invention is arranged in the low-pressure line through which the low-pressure refrigerant passes through the expansion valve, the outlet pressure and the inlet pressure of the compressor pursued by the present invention can be controlled simultaneously .

7 is an example of a heat pump for controlling the refrigerant storage amount by a refrigerant transfer pump, not by a piston. The variable capacity refrigerant storage means RS3 comprises two rooms for storing the refrigerant, that is, a room (Ra) to a room (Rb), a refrigerant transfer pump (P1) and a four way valve (V4p) . When the volume of one side refrigerant storage is increased, the volume of the other side refrigerant storage volume is reduced.

(That is, the outlet of the refrigerant transfer pump P1 is connected to the refrigerant storage chamber Ra and the inlet of the refrigerant transfer pump P1 is connected to the outlet of the condenser HXO) , When the refrigerant transfer pump (P1) transfers the refrigerant, the refrigerant storage amount in the refrigerant storage room (Ra) increases and the outlet pressure of the compressor (C1) decreases.

 On the other hand, in FIG. 7, the four sides V4p are rotated 90 degrees so that the outlet of the refrigerant transfer pump P1 is connected to the outlet of the condenser HXO and the inlet of the refrigerant transfer pump P1 is connected to the refrigerant storage chamber Ra), and when the refrigerant transfer pump (P1) transfers the refrigerant, the refrigerant storage amount in the refrigerant storage chamber (Ra) is reduced and the outlet pressure of the compressor (C1) is increased.

This embodiment is an embodiment of a method of operating a heat pump (using refrigerant) in a cooling (including freezing) mode.

This will be described below with reference to FIG. The configuration of the heat pump shown in Fig. 6 has been described in detail in the third embodiment, and therefore will not be described.

 The heat pump according to the present invention includes a refrigerant storage unit connected to a compressor, a condenser, an expansion valve, and an evaporator through a hermetically sealed refrigerant line, and connected to a refrigerant line to control a circulation amount of the refrigerant.

The control method for the heat pump includes the steps of setting a target temperature of the evaporator, controlling the expansion valve and the evaporator, controlling the inlet pressure of the compressor, setting the target temperature of the condenser, And adjusting the amount of the refrigerant to control the outlet pressure of the compressor. Here, the step of controlling the superheating degree of the evaporator and / or the step of controlling the supercooling degree of the condenser may be further included.

Hereinafter, a method of controlling the heat pump according to the present invention will be described as an example

1) It is desirable to obtain the evaporator target temperature by formula (1) or formula (2).

     Evaporator target temperature = Emission temperature - Td - - - (Equation 1)

     Evaporator target temperature = cooling (freezing) set temperature - Td - - - (Equation 2)

   Where Td is a predetermined constant greater than 0 (e.g., 15.0)

   The evaporator target temperature obtained by the above equation (1) varies according to the inside temperature, and the evaporator target temperature obtained by the formula (2) has a fixed value.

The compressor inlet pressure target value is found in the refrigerant pressure-temperature chart using the target temperature. It is preferable that the current cooling load magnitude is obtained by using the temperature difference (= the inside temperature - the target temperature of the evaporator) and the size of the cooling space.

In this case, the indoor temperature is the temperature of the space to be cooled, and it means the room temperature when the heat pump is installed in the building, and the internal temperature of the vehicle when the heat pump is installed in the vehicle.

2) The inlet pressure of the compressor (C1) is controlled by adjusting the expansion valve (EV) and the compressor (C1).

(Assumption 1) The evaporator (HXI) target temperature is 16 占 폚, and (hypothesis 2) the evaporator (HXI) inside the evaporator (more precisely at the exit of the expansion valve (Hereinafter referred to as " particles "for ease of description) exist in the refrigerant particles (between the inlet of the compressor C1) The inlet pressure of the compressor (C1)] is 4 atm, and (assume 3) the temperature corresponding to 4 atmospheric pressure in the pressure-temperature chart of the refrigerant used is assumed to be 16 deg.

Here, there are many driving conditions of the expansion valve (EV) and the compressor (C1) for setting the inlet pressure of the compressor (C1) to 4 atm. The amount of refrigerant flowing into the evaporator HXI (via the expansion valve EV) and the amount of refrigerant flowing out of the evaporator HXI (via the compressor C1) are calculated in the state where 400 refrigerant particles exist in the present evaporator HXI If the amount of refrigerant is equalized, the pressure inside the evaporator (HXI) is always 4 atm. That is, the evaporator (HXI) temperature is always 16 ° C.

Therefore, according to (Assumption 1) to (Assumption 3), 400 refrigerant particles are present in the evaporator HXI, while when the cooling load is large, the amount of refrigerant passing through the evaporator per unit time is increased, It is preferable to drive the heat pump by a method of reducing the amount of refrigerant passing through the evaporator per hour. This is particularly preferable when the cooling air volume of the heat pump is in the automatic adjustment mode.

Unlike an electric car, an engine car is usually driven by a car engine. Since the engine rotation speed (RPM) changes from time to time during vehicle operation, the compression speed of the compressor also varies from time to time. According to the present invention, it is preferable that the amount of refrigerant passing through the compressor per unit time is constant. Therefore, it is preferable that the amount of compressed refrigerant once decreases as the engine rotation speed increases, and the amount of compressed refrigerant once increases as the engine rotation speed decreases.

3) The degree of superheat is particularly preferably obtained by the formula (3).

Overheat = actual temperature - theoretical temperature - - - (Equation 3)

Here, the measured temperature is the refrigerant temperature measured at the outlet of the evaporator (HXI). The theoretical temperature is obtained from the pressure-temperature chart of the refrigerant used. At this time, the pressure obtained from the measured temperature measurement site is used.

3-1) When the cooling air flow rate is in the automatic adjustment mode: The amount of refrigerant passing through the evaporator (HXI) per unit time is determined by the refrigeration load (see step 2), and the superheat degree is determined by the speed of the evaporator fan .

More specifically, if the superheating degree is high, the heat supplied to the evaporator (HXI) is reduced (ie, the evaporator fan (FXI) is lowered) to reduce the superheat degree. If the superheat degree is low, (I.e., increasing the evaporator fan (FXI) rate) to increase the superheat. In actual implementation of this method, the superheat degree has a target superheat degree and difference, and because of the limitation of each accessory, the expansion valve (EV) opening or the compressor (C1) control finer or easier than the evaporator fan If the superheat degree can be controlled, it is preferable to control the superheat degree with an expansion valve or a compressor. At this time, the inlet pressure of the compressor (C1) will be approximately equal to the target pressure.

3-2) When the cooling air flow rate is in the manual adjustment mode: The air flow rate, ie the evaporator fan (FXI) speed, is already set manually. Therefore, it is preferable to control the degree of superheat to the amount of circulating refrigerant.

More specifically, if the amount of refrigerant passing through the evaporator (HXI) per unit time is lower than a proper level, the amount of cool air is reduced and the degree of superheat increases. If the amount of coolant is higher than a proper level, Therefore, it is preferable to control the degree of superheat by controlling the amount of refrigerant passing through the evaporator (HXI) per unit time.

Here, the amount of refrigerant passing through the evaporator HXI per unit time is preferably controlled by the expansion valve EV and the compressor C1. At this time, it is natural that the temperature of the evaporator (HXI) and the inlet pressure of the compressor (C1) are determined by the number of refrigerant particles present in the evaporator (HXI). It is a matter of course that the superheat degree is controlled without changing the inlet pressure of the compressor C1.

In actual implementation of this method, the superheat degree of the superheat degree is small and the difference is small, and because of the limitation of each accessory, the evaporator fan FXI is more finely or easily superheated than the expansion valve (EV) If it is possible to control the degree of superheat, it is preferable to control the superheat degree with the evaporator fan FXI. At this time, the inlet pressure of the compressor (C1) will be approximately equal to the target pressure.

4) The outlet pressure of the compressor (C1) is controlled by the variable capacity refrigerant storage means. Since the method of adjusting the outlet pressure in the above embodiments has been described in detail, the description of the method of adjusting the outlet pressure is omitted.

Basically, the temperature of the condenser (HXO) is preferably higher than the outside temperature by a predetermined value so as to facilitate the release of heat to the outside air. (Condenser target temperature setting - case 1) and the supercooling degree is preferably adjusted by the speed of the condenser fan (FNO).

The amount of refrigerant circulating through the heat pump per unit time is determined by [step 2) and step 3). Therefore, by selecting the outlet pressure of the compressor (C1), the amount of heat to be dissipated in the condenser (HXO) can be calculated. More specifically, by using the circulating refrigerant amount per unit time and the outlet pressure of the compressor (C1), it is possible to obtain the heat radiation load for causing the phase transition of the refrigerant from the gas to the liquid from the temperature obtained from the pressure-temperature chart of the refrigerant used.

According to the embodiments of the present invention described above, the outlet pressure of the compressor (C1) is adjustable without fluctuating the inlet pressure. Then, from the compressor C1 inlet pressure and outlet pressure, the calculated heat radiation load amount, the condenser fan FNO air volume [for the heat exchange with the heat radiation load amount] (the FNO air volume considering the vehicle speed in the case of an automobile) , The energy consumed to process the heat radiation load can be calculated. Therefore, it is preferable to calculate the energy consumed by variously applying the outlet pressure of the compressor (C1), and to select the outlet pressure of the compressor (C1) having the smallest energy consumption (that is, the condenser (HXO) temperature). (Condenser target temperature setting - Case 2)

5) It is particularly preferable to obtain the subcooling degree by (formula 4).

Subcooling = measured temperature - theoretical temperature - - - (Equation 4)

Here, the actual temperature is the refrigerant temperature measured at the outlet of the condenser (HXO). The theoretical temperature is obtained from the pressure-temperature chart of the refrigerant used. At this time, the pressure obtained from the measured temperature measurement site is used.

In order to increase the heat pump performance coefficient, the subcooling degree is preferably controlled to an appropriate value. The degree of supercooling may fluctuate due to external humidity, wind speed of natural wind, etc. The subcooling is preferably controlled at the speed of the condenser fan (FNO). That is, the superheat degree can be controlled without fluctuating the outlet pressure of the compressor (C1). If the speed of the condenser fan FNO is near the limit value, it is of course possible to adjust the subcooling degree to the outlet pressure of the compressor C1.

Since the heat pump control procedure described above is a procedure involving multiple cases, some steps may alternatively be selected in an actual heat pump implementation. It should be noted that the above-described control procedure is not a fixed order but can be implemented even if implemented in a different order.

One embodiment of the heat pump driving method of the present invention has been described in detail above.

Hereinafter, an embodiment of the present invention (air conditioning cooling mode) will be described with reference to FIG.

First, the structure of the heat pump includes a compressor (C1) for compressing the gaseous refrigerant; A condenser (HXO, external heat exchanger) that converts gas refrigerant of high temperature and high pressure into heat by exchanging heat; A first expansion valve (EV1) for expanding the refrigerant; An evaporator (HXI, internal heat exchanger) that converts the expanded refrigerant into heat by exchanging heat; And a second expansion device (RS2) for discharging the refrigerant from the refrigerant storage means (RS4). The refrigerant storage device (RS4) includes a variable capacity refrigerant storage means (RS4) And a valve EV2 (hereinafter also referred to as "refrigerant outlet valve"). One side of the refrigerant inlet valve V1 is connected to the outlet of the condenser HXO and one side of the refrigerant outlet valve EV2 is connected to the inlet of the evaporator HXI.

Hereinafter, a preferable driving method will be described.

First the valve V1 for introducing the refrigerant into the refrigerant storage means RS4 is completely closed and the second expansion valve EV2 for discharging the refrigerant is fully opened and the compressor C1 is operated. Then, a high-pressure refrigerant line is formed from the compressor outlet to the inlet of the first expansion valve EV1, and a low-pressure refrigerant line is formed from the inlet of the compressor C1 to the refrigerant storage means RS4. At this time, it is natural that there is no refrigerant stored in the refrigerant storage means RS4 (exaggeratively).

In general, when the cooling load is large, the compressor (C1) compresses a lot of refrigerant per unit time, so that the outlet pressure of the compressor (C1) is often high. At this time, if the outside air temperature is low, it is desirable to lower the outlet pressure of the compressor (C1) and the condenser (HXO) temperature to an appropriate level. For example, there is a large load of cooling, such as a fire-intensive kitchen, a crowded place, and a car running at high speed with a window closed during the day,

When the outside air temperature is as low as 20 占 폚, it is desirable to lower the compressor outlet pressure and the condenser (HXO) temperature to an appropriate level.

The preferred order of storing the refrigerant in the refrigerant storage means RS4 is as follows: 1) The second expansion valve EV2 for discharging the refrigerant from the refrigerant storage means RS4 is fully closed (the inside of the refrigerant storage means RS4) 2) The refrigerant inlet valve V1 is opened by a predetermined value or gradually so that the liquid refrigerant condensed in the condenser HXO flows into the refrigerant storage means RS4. Then, the inside of the refrigerant storage means RS4 gradually becomes high pressure.

At this time, the refrigerant inlet valve (V1) is slowly opened because the refrigerant flows from the high-pressure line and the pressure of the high-pressure line is rapidly lowered, so that the refrigerant can change from the liquid state to the gas state.

3) When the outlet pressure of the compressor C1 and the temperature of the condenser HXO are lowered to an appropriate level, the valve V1 for introducing the refrigerant into the refrigerant storage means RS4 is fully closed. That is, when the outside air temperature is maintained at a constant level, the valve (V1) and the second expansion valve (EV2) are kept in a locked state. [Reference, inlet pressure of valve (V1) > = internal pressure of refrigerant storage means (RS4) > = outlet pressure of the second expansion valve (EV2)

In addition, it may be necessary to increase the compressor outlet pressure and the condenser temperature as the outside air temperature becomes high during operation of the heat pump according to the present invention. In this case, 4) the second expansion valve EV2 for discharging the refrigerant to the refrigerant storage means RS4 is opened by a predetermined value or gradually. 5) The refrigerant stored in the refrigerant storage means RS4 at a high pressure passes through the second expansion valve EV2, and is discharged to the low-pressure To the inlet of the evaporator (HXI, indoor heat exchanger). 6) The refrigerant replenished to the low pressure line is moved to the high pressure line by the compressor C1. 7) When the low pressure line becomes the same pressure as before the refrigerant replenishment, the outlet pressure of the compressor C1 and the condenser HXO temperature .

At this time, the refrigerant storage means RS4 is preferably formed in the form of a gas-liquid separator. This is to allow the liquid and the gas stored in the refrigerant storage device RS4 to flow out from the gas. The refrigerant storage means RS4 is preferably installed in an indoor unit provided with an expansion valve EV1 and an evaporator HXI.

The reason why the expansion valve EV2 is used as the refrigerant outflow valve EV2 is to use the thermal energy of the refrigerant stored in the refrigerant storage means RS4. On the other hand, it is of course also possible to use a refrigerant outlet valve as a refrigerant inlet valve (other than an expansion valve) if the evaporator capacity is large or the compressor is equipped with a gas-liquid separator.

A modification of this embodiment will be described below with reference to Fig.

8 and 9 differ from each other in that the refrigerant flowing out of the refrigerant storage means is introduced into the heat pump system. That is, the refrigerant stored in the refrigerant storage means RS4 in the heat pump of FIG. 8 is introduced to the inlet of the evaporator (HXI). On the other hand, the refrigerant stored in the refrigerant storage means RS5 in the heat pump of Fig. 9 is introduced to the outlet of the evaporator (HXI). The refrigerant passing through the introduced refrigerant and the evaporator HXI moves to the input side of the compressor C1 via the gas-liquid separator VLS.

It is preferable that the heat pump is disposed in an outdoor unit provided with a compressor (C1) and a condenser (HXO). The heat pump of FIG. 9 is suitable when the physical size of the refrigerant storage means RS5 according to the present invention is large. More specifically, when the amount of refrigerant to be stored in the refrigerant storage means (RS5) is large due to the design of the heat pump, the physical size of the refrigerant storage means (RS5) becomes large. When the size of the refrigerant storage means (RS5) 9 heat pump is preferable.

On the other hand, an application of the refrigerant storage means of the present invention is to change the outlet pressure of the compressor in order to set an appropriate condenser temperature when the outside air temperature changes. Therefore, if the outside air temperature does not fluctuate, fluctuations in the refrigerant storage amount are often not frequent. Therefore, even if the heat energy of the stored refrigerant can not be used in the evaporator, the heat energy loss will not be large.

In general, it is preferable that the refrigerant storage amount is also gradually changed since the ambient temperature gradually changes as the solution rises. One preferable control when the outside air gradually goes up is to intermittently open and close the refrigerant outlet valve V2 slightly to increase the amount of circulating refrigerant, thereby increasing the compressor outlet pressure. At this time, it is natural that the refrigerant inlet valve V1 should be completely closed.

And, in the case where the outside air temperature gradually decreases, a preferable control is to intermittently open and close the refrigerant inlet valve V1 slightly at a small interval, thereby reducing the amount of circulating refrigerant, thereby lowering the compressor outlet pressure. At this time, it is natural that the refrigerant outlet valve V2 should be completely closed.

In the above description, one side of the refrigerant inflow valve V1 is connected to the outlet of the condenser (HXO). It goes without saying that even if one side of the refrigerant inflow valve V1 is connected to the inlet of the condenser HXO, it does not depart from the spirit of the present invention. That is, it is possible to store (at a high pressure) refrigerant in the refrigerant storage means, and as a result, the compressor outlet pressure is regulated.

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

It will be appreciated by those skilled in the art that the inlet and outlet pressures of the compressors described in this invention can be replaced by the evaporator outlet pressure and the condenser outlet pressure used to calculate superheat and subcooling.

The preferred embodiments of the present invention have been described in detail above.

In the present invention, the case where the heat pump is operated in the cooling mode has been described in detail, but it is natural that the concept of the present invention can be applied even in the heating mode. That is, the compressor inlet pressure and the outlet pressure are individually adjusted so that the temperature of the condenser and the vaporizer, which are heat exchangers, is lower than the temperature of the air used for heat exchange ("liquid" in the case of a water tank, "medium" It is possible to set it as high or low as the value Thus, an energy-saving heat pump is provided, since heat exchange can be performed with an optimum temperature difference with the heat exchange medium.

In the embodiments of the present invention, the compressor, the outdoor heat exchanger, the indoor heat exchanger, and the expansion valve have been described as one compressor, but it is obvious to those skilled in the art that a plurality of the present invention can be implemented.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Therefore, the embodiments of the present invention disclosed in the present specification and drawings are merely illustrative of the technical contents of the present invention and are intended to illustrate specific examples of the present invention in order to facilitate understanding of the present invention, and are not intended to limit the scope of the present invention.

According to the heat pump having the variable-capacity refrigerant storage means according to the present invention, the inlet pressure and the outlet pressure of the compressor can be individually adjusted simultaneously, and heat exchange can be performed with the optimum temperature difference with the heat exchange medium. There is an effect that is provided, and the possibility of industrial use is very high.

Particularly, in the automobile industry including an electric vehicle, when the heat pump operates in the cooling mode, the heater is not required to be operated, and the fuel efficiency of the vehicle is improved, so that the possibility of industrial use is very high.

HXO external heat exchanger
HXI internal heat exchanger
EV, EV1, EV2 expansion valve
C, C1 compressor
RS, RS1, RS2, RS3, RS4, RS5 variable capacity refrigerant storage means
PR1, PR2 piston
Ra, Rb, Rc refrigerant storage room
V4c, V4c four sides
P1 refrigerant transfer pump
FNI, FNO Heat Exchanger Fans
V1 and V2 valves

Claims (14)

A heat pump comprising a compressor, a condenser, an expansion valve, and an evaporator, wherein the refrigerant is circulated through a closed refrigerant line,
And refrigerant storage means connected to the refrigerant line for storing a part of the refrigerant and controlling the amount of circulation of the refrigerant circulated in the refrigerant line,
Wherein the outlet pressure of the compressor is regulated by the amount of circulation of the refrigerant controlled by the refrigerant storage means.
The refrigerating device according to claim 1,
And a heat pump installed between the expansion valve and the outlet of the compressor.
The refrigerating device according to claim 1,
A cylinder having an internal space for storing the refrigerant;
An inner wall dividing one side and the other side of the inner space; And
And movement means for reciprocating the inner wall in the inner space,
Wherein the one inner space has a higher density of refrigerant than the other, and the other inner space has lower density refrigerant than the other.
4. The apparatus according to claim 3,
And a pump for transferring the refrigerant to one side of the internal space.
4. The apparatus according to claim 3,
And a piston reciprocating the inner wall.
The method according to claim 1,
The inlet pressure of the compressor being regulated by the expansion valve,
Wherein the inlet pressure and the outlet pressure of the compressor are individually adjusted.
The refrigeration system of claim 1, wherein the refrigerant storage means
An inner space for storing the refrigerant;
A refrigerant inflow valve disposed between the internal space and the condenser outlet (or any one of the condenser inlets); And
And a refrigerant outflow valve installed between the inner space and the evaporator inlet (or any one of the evaporator outlets).
A method of controlling a heat pump including a compressor, a condenser, an expansion valve, and an evaporator connected through a closed refrigerant line and connected to the refrigerant line to control a circulation amount of the refrigerant,
Setting a target temperature of the condenser;
Controlling the expansion valve and the evaporator to control an inlet pressure of the compressor; And
Controlling an amount of the refrigerant stored in the refrigerant storage means to control an outlet pressure of the compressor.
The refrigerating device according to claim 8,
A valve disposed between the expansion valve and the outlet of the compressor; Wherein the heat pump control method comprises:
10. The refrigerant storage device according to claim 9 ,
A cylinder having an internal space for storing the refrigerant;
An inner wall dividing one side and the other side of the inner space; And
And movement means for reciprocating the inner wall in the inner space,
A high-density refrigerant is stored in one inner space and a low-density refrigerant is stored in the other inner space; Wherein the heat pump control method comprises :
11. The apparatus according to claim 10,
And a pump for transferring the refrigerant to one side of the inner space; Wherein the heat pump control method comprises:
11. The apparatus according to claim 10,
Comprising a piston reciprocating the inner wall; Wherein the heat pump control method comprises:
9. The method of claim 8,
The inlet pressure of the compressor being regulated by the expansion valve,
The inlet and outlet pressures of the compressor being individually regulated; Wherein the heat pump control method comprises:
The refrigerant storage device according to claim 8, wherein the refrigerant storage means
An inner space for storing the refrigerant;
A refrigerant inflow valve disposed between the internal space and the condenser outlet (or any one of the condenser inlets); And
A refrigerant outflow valve installed between the inner space and the evaporator inlet (or any one of the evaporator outlets); Wherein the heat pump control method comprises:

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