JP4884365B2 - Refrigeration air conditioner, refrigeration air conditioner outdoor unit, and refrigeration air conditioner control device - Google Patents

Description

  The present invention relates to a refrigeration air conditioner, an outdoor unit of the refrigeration air conditioner, and a control device for the refrigeration air conditioner, and more particularly to a refrigeration air conditioner having a re-evaporating means for overheating a compressor suction refrigerant.

  As a conventional refrigeration air conditioner, for example, “... required to superheat the refrigerant at the outlet of the evaporator, which is provided between the refrigeration cycle and the evaporator and the compressor, and superheats to the target superheat degree. A re-evaporating means having a sufficient heat exchange amount, an overheat detecting means for detecting a superheat characteristic corresponding to the degree of superheat of the refrigerant sucked at the inlet of the compressor after being heated by the re-evaporating means, and the overheat detecting means Control means for adjusting and controlling the opening area of the low-pressure-side throttling device so that the refrigerant at the outlet of the evaporator in a wet state becomes the target superheat degree at the inlet of the compressor based on the information on the degree of superheat detected by Is provided (for example, see Patent Document 1).

JP 2001-263831 A (Claim 1, FIG. 1)

However, the conventional refrigeration air conditioner has the following problems.
First, as in the conventional example described in Patent Document 1 above, when a heater is used as the re-evaporation means, there is a decrease in product COP and an increase in cost due to an increase in input. When high-low pressure heat exchange is used for the re-evaporation means, the heat exchange amount changes depending on the state of the refrigerant, that is, the refrigerant temperature and the circulation amount. Since the amount of heat exchange changes due to changes, etc., even if the refrigerant state at the compressor inlet is controlled to a predetermined target superheat degree, the refrigerant state at the evaporator outlet does not necessarily reach the target dryness. There was a risk of deteriorating sex.

  In view of the above problems, the present invention detects the amount of heat exchange in the high-low pressure heat exchanger (internal heat exchanger) and changes the target superheat degree at the compressor inlet according to the amount of heat exchange to evaporate. A highly reliable refrigerating and air-conditioning system that maintains the dryness of the refrigerant at the outlet of the evaporator at a predetermined target value, realizes high-efficiency operation, and does not cause problems such as dew escaping due to drying of the evaporator. The purpose is to obtain. Furthermore, it aims at obtaining the outdoor unit and control apparatus which are used for such a refrigeration air conditioner.

The refrigeration air conditioner according to the present invention is a refrigeration air conditioner in which a compressor, a condenser, a first pressure reducing device, a second pressure reducing device, and an evaporator are connected in an annular shape, wherein the first pressure reducing device and the second pressure reducing device are An internal heat exchanger for exchanging heat between the refrigerant between the decompressor and the refrigerant between the evaporator and the compressor, and a supercooling degree detecting means for detecting the degree of supercooling of the refrigerant at the condenser outlet The first control means for adjusting the flow rate of the first pressure reducing device so that the degree of supercooling detected by the degree of supercooling detection means becomes a predetermined value, and the internal heat exchanger Detected by a heat exchange amount detecting means for detecting a heat exchange amount, a superheat degree detecting means for detecting the degree of superheat of the refrigerant at the compressor inlet after being heated by the internal heat exchanger, and the heat exchange amount detecting means From the internal heat exchange amount, the refrigerant at the outlet of the evaporator is saturated gas A target superheat degree calculating means for calculating the degree of superheat of the compressor inlet of the refrigerant when the on purpose made, the overheating degree calculated by the target superheat degree calculating unit and the target degree of superheat, compressor where the superheating degree detecting means for detecting A second control device that adjusts the flow rate of the second decompression device so that the superheat degree of the refrigerant at the machine inlet approaches the target superheat degree, and the heat exchange amount detecting means is a refrigerant at the outlet of the condenser A first enthalpy of the internal heat exchanger inlet refrigerant of the high temperature side refrigerant is calculated based on the temperature information, and the internal heat exchange of the high temperature side refrigerant is calculated based on the refrigerant temperature information of the internal heat exchanger outlet of the high temperature side refrigerant Calculating a second enthalpy of the refrigerant at the outlet of the reactor, calculating an enthalpy difference (Δh) between the first enthalpy and the second enthalpy, and then, based on the enthalpy difference (Δh), the internal heat exchanger Heat exchange at (Q) is calculated, and the target superheat degree calculating means obtains the constant pressure specific heat (Cp) in the saturated gas state of the refrigerant based on the refrigerant temperature information in the evaporator, and the heat exchange amount (Q) and The degree of superheat of the refrigerant at the compressor inlet is calculated based on the constant pressure specific heat (Cp) at the inlet of the internal heat exchanger for the low temperature side refrigerant.

  In this invention, by detecting the amount of heat exchange in the internal heat exchanger, even if the amount of internal heat exchange changes due to changes in operating conditions, changes in compressor frequency, etc. By changing the target dryness of the refrigerant sucked in the compressor, the dryness of the refrigerant at the outlet of the evaporator is maintained at a predetermined target value to achieve high-efficiency operation and the exposure caused by the drying of the evaporator Thus, it is possible to realize the operation of a highly reliable refrigeration air conditioner that does not cause problems such as the above.

Embodiment 1 FIG.
A first embodiment of the present invention is shown in FIG. FIG. 1 is a refrigerant circuit diagram of the refrigerating and air-conditioning apparatus according to the present embodiment. The compressor 3, the condenser heat exchanger 15, the internal heat exchanger 14, the decompression device, the first expansion valve 10 and the evaporator heat exchange. The vessel 16 is connected in an annular shape. The first expansion valve 10 is an electronic expansion valve whose opening degree is variably controlled. The condenser heat exchanger 15 and the evaporator heat exchanger 16 exchange heat with air blown by a fan (not shown) or the like.

  A temperature sensor 13 (referred to as “temperature sensor 13” in this manner when temperature sensors 13a, 13k,... Described later are collectively referred to) and an expansion valve 10 are connected to the measurement control device 12. The temperature sensor 13 a is on the discharge side of the compressor 3, the temperature sensor 13 k is on the refrigerant flow path in the middle part of the condenser heat exchanger 15, the temperature sensor 131 is between the condenser heat exchanger 15 and the internal heat exchanger 14, and the temperature sensor 13 d is Between the internal heat exchanger 14 and the expansion valve 10, a temperature sensor 13e is provided on the suction side (inlet side) of the compressor 3, and measures the refrigerant temperature at the installation location. The temperature sensor 13m measures the air temperature around the condenser heat exchanger 15.

  Temperature sensors 13n, 13o, and 13p are installed in and around the evaporator heat exchanger 16, the temperature sensor 13n is on the refrigerant flow path in the middle of the evaporator heat exchanger 16, and the temperature sensor 13o is an evaporator heat exchanger. 16 is provided between the expansion valve 10 and the refrigerant temperature at each installation location. The temperature sensor 13p measures the temperature of the air taken into the evaporator heat exchanger 16.

  The temperature sensors 13k and 13n can detect the refrigerant saturation temperature at high and low pressure by detecting the refrigerant temperature in the gas-liquid two-phase state in the middle of the heat exchanger.

  Further, the measurement control device 12 in the outdoor unit 1 is based on the measurement information of the temperature sensor 13 and the operation content instructed by the user of the refrigeration air conditioner, and the operation method of the compressor 3, the heat exchanger 15 for the condenser, The fan air flow rate of the evaporator heat exchanger 16 and the opening degree of the expansion valve 10 are controlled. The measurement control device 12 not only functions as the control device of the present invention, but also functions as an arithmetic processing unit of the heat exchange amount detection means 12a, the superheat degree detection means 12b, and the target superheat degree calculation means 12c of the present invention. (However, in FIG. 1, these means 12a to 12c are described for convenience as if they were built in). The heat exchange amount detection means 12a of the present invention includes temperature sensors 13l and 13d and a measurement control device 12, and the heat exchange amount (Q) in the internal heat exchanger 14 based on the outputs of the temperature sensors 13l and 13d. Ask for. The superheat degree detection means 12b includes temperature sensors 13e and 13n and a measurement control device 12, and obtains the superheat degree of the refrigerant sucked from the compressor based on the outputs of the temperature sensors 13e and 13n. The target superheat degree calculating means 12c is composed of a temperature sensor 13n and a measurement control device 12, and obtains a constant pressure specific heat (Cp) of the saturated gas of the refrigerant based on the output of the temperature sensor 13n, and the constant pressure specific heat (Cp) and Based on the heat exchange amount (Q), the degree of superheat of the refrigerant sucked in the compressor when the evaporator outlet state becomes a saturated gas state is calculated. The details of the arithmetic processing of these heat exchange amount detection means 12a, superheat degree detection means 12b, and target superheat degree calculation means 12c will be described later.

  Next, the operation | movement operation | movement in this refrigerating air conditioner is demonstrated based on Ph diagram (Mollier diagram) shown in FIG. The high-temperature and high-pressure gas refrigerant discharged from the compressor 3 (point 1 in FIG. 2) flows into the condenser heat exchanger 15, where it condenses and liquefies while dissipating heat, and becomes a high-pressure and low-temperature refrigerant (point 2 in FIG. 2). . The refrigerant leaving the condenser heat exchanger 15 is cooled by the internal heat exchanger 14 by exchanging heat with the refrigerant sucked into the compressor 3 (point 3 in FIG. 2). Thereafter, the pressure is reduced to a low pressure by the expansion valve 10 to become a two-phase refrigerant (FIG. 2, point 5), and then flows into the evaporator heat exchanger 16, where it absorbs heat and evaporates and gasifies (point 6 in FIG. 2). Supply cold energy to load-side media such as water and water. The low-pressure gas refrigerant exiting the evaporator heat exchanger 16 is heated by exchanging heat with the high-pressure refrigerant in the internal heat exchanger 14 (point 7 in FIG. 2), and then sucked into the compressor 3 and compressed and discharged to a high pressure. (Fig. 2, point 1).

  Next, a method for controlling the expansion valve will be described. The expansion valve 10 is preset with a refrigerant superheat degree SH of the compressor 3 suction detected by the temperature difference between the compressor 3 suction temperature detected by the temperature sensor 13e and the saturation temperature of the low-pressure refrigerant detected by the temperature sensor 13n. The controlled target value is controlled to be 10 ° C., for example. When the refrigerant superheat degree SH is larger than the target value, the opening degree of the expansion valve 10 is large, and when the refrigerant superheat degree SH is smaller than the target value, the opening degree of the expansion valve 10 is controlled to be small.

  In this refrigeration cycle, the suction refrigerant superheat degree SH of the compressor 3 is generated by heat exchange with the high-temperature refrigerant in the internal heat exchanger 14, and is therefore a control target of the expansion valve 10 according to the heat exchange amount. It is necessary to change the target value of the refrigerant superheat degree.

  That is, when the target value of the refrigerant 3 superheat degree of the compressor 3, which is the control target of the expansion valve 10, is set larger than the intake refrigerant superheat degree of the compressor 3 generated by the heat exchange amount in the internal heat exchanger 14. This is because the outlet refrigerant state of the evaporator heat exchanger 16 becomes a superheated gas state having a degree of dryness greater than 1, and the performance is reduced, and a part of the refrigerant in the evaporator heat exchanger 16 becomes a heated gas state. This causes problems such as flying out. Further, when the target value of the refrigerant superheat degree of the compressor 3 is set to be small, the outlet refrigerant state of the evaporator heat exchanger 16 becomes a two-phase state with a dryness of 1 or less, causing problems such as performance degradation. .

  The relationship between the evaporator outlet dryness and the evaporator capacity is shown in FIG. The evaporator capacity is maximized when the evaporator outlet refrigerant state is a saturated gas state with a dryness of 1. For this reason, from the viewpoint of increasing the efficiency of the refrigeration cycle, it is desirable to set the refrigerant superheat degree of the compressor 3 so that the evaporator outlet refrigerant state has a dryness of 1, according to the internal heat exchange amount.

Here, a method for setting the intake refrigerant superheat degree of the compressor 3 as a control target of the expansion valve 10 will be described with reference to the Ph diagram of FIG. As described above, the suction refrigerant heating degree of the compressor 3 is generated by heat exchange with the high-pressure refrigerant in the internal heat exchanger 14, so that the pressure state changes when the operating state changes due to a load change or the like. The amount will also change. The amount of heat exchange in the internal heat exchanger 14 can be obtained by the following equation.
Q = Gr × Δh = Gr × SHm × Cp
Where, Q: heat exchange amount [kJ], Δh: enthalpy difference [kJ / kg], Gr: refrigerant circulation rate [kg / h], SHm: intake refrigerant superheat degree [° C], Cp: constant pressure specific heat [kJ / kg · ° C]. Regarding the enthalpy difference of the high-pressure refrigerant, the saturated liquid enthalpy at each temperature is calculated from the inlet temperature of the internal heat exchanger 14 (temperature sensor 13l) and the outlet temperature of the internal heat exchanger 14 (temperature sensor 13d), and the difference can be obtained. It ’s fine. For the constant pressure specific heat [kJ / kg · ° C.], the constant pressure specific heat in the saturated gas state at the temperature detected by the temperature sensor 13n of the evaporator heat exchanger 16 may be calculated. If the above state quantities are known, the degree of superheat of the refrigerant sucked in the compressor 3 in the saturated gas state where the degree of dryness of the outlet refrigerant of the evaporator heat exchanger 16 is 1.0 can be obtained. The control target value may be 10.

That is, the measurement control device 12 performs the following arithmetic processing and control.
(1) The measurement control device 12 (heat exchange amount detection means 12a) calculates saturated liquid enthalpies (first enthalpy and second enthalpy) based on the outputs of the temperature sensor 13l and the temperature sensor 13d, respectively. Difference (Δh) is obtained. Then, a heat exchange amount (Q) in the internal heat exchanger 14 is obtained based on the enthalpy difference (Δh) and the refrigerant circulation amount (Gr).
(2) The measurement controller 12 (superheat degree detection means 12b) detects the superheat degree of the refrigerant sucked in the compressor 3 after being heated by the internal heat exchanger 14 based on the outputs of the temperature sensors 13e and 13n.
(3) The measurement control device 12 (target superheat degree calculation means 12c) calculates the constant pressure specific heat (Cp) in the saturated gas state based on the output of the temperature sensor 13n, and the heat exchange amount (Q) and the constant pressure specific heat ( Based on Cp), the suction refrigerant superheat degree of the compressor 3 when the outlet state of the evaporator heat exchanger 16 becomes a saturated gas state is obtained and set as the target superheat degree.
(4) The measurement control device 12 sets the superheat degree calculated above as the target superheat degree, and adjusts the flow rate of the expansion valve 10 so that the compressor 3 suction refrigerant superheat degree detected as described above becomes the target superheat degree. .

  As described above, according to the first embodiment, the heat exchange amount (Q) in the internal heat exchanger 14 is detected, and the suction refrigerant superheat degree of the compressor 3 after being heated by the internal heat exchanger 14 is determined. Detecting and calculating the compressor 3 suction refrigerant superheat degree when the outlet state of the evaporator heat exchanger 16 becomes a saturated gas state based on the internal heat exchange amount (Q) as the target superheat degree, and sucking refrigerant superheat degree of the compressor 3 Since the flow rate of the expansion valve 10 is adjusted so that the target superheat degree becomes the target degree of superheat, even if the internal heat exchange amount changes due to a change in the operating state, a change in the compressor frequency, or the like, the heat exchange amount By changing the target dryness of the refrigerant sucked from the compressor in accordance with (Q), the dryness of the refrigerant at the outlet of the evaporator is maintained at a predetermined target value, realizing high-efficiency operation, and an evaporator heat exchanger No problems such as dew escaping due to drying of 16 Lai highly refrigeration air conditioning system is obtained.

Embodiment 2. FIG.
Next, a second embodiment of the present invention is shown in FIG. FIG. 4 is a refrigerant circuit diagram of the refrigerating and air-conditioning apparatus according to the present embodiment. In the outdoor unit 1, the compressor 3, the four-way valve 4, the outdoor heat exchanger 11, the first expansion valve 10 that is a decompression device, and the inside A heat exchanger 14 and a second expansion valve 8 which is a pressure reducing device are mounted. The compressor 3 is a type in which the rotation speed is controlled by an inverter and the capacity is controlled. The first expansion valve 10 and the second expansion valve 8 are electronic expansion valves whose opening degrees are variably controlled. The outdoor heat exchanger 11 exchanges heat with the outside air blown by a fan (not shown) or the like. An indoor heat exchanger 6 is mounted in the indoor unit 2. The gas pipe 5 and the liquid pipe 7 are connection pipes that connect the outdoor unit 1 and the indoor unit 2. As the refrigerant of this refrigeration air conditioner, R410A, which is an HFC-based mixed refrigerant, is used (the same applies to Embodiments 2 and 3 described later).

  A measurement control device 12 and a temperature sensor 13 are installed in the outdoor unit 1. The temperature sensor 13a is on the discharge side of the compressor 3, the temperature sensor 13b is on the refrigerant flow path in the middle of the outdoor heat exchanger 11, the temperature sensor 13c is between the outdoor heat exchanger 11 and the first expansion valve 10, and the temperature sensor 13d is the second. Between the expansion valve 8 and the internal heat exchanger 14, the temperature sensor 13e is provided on the suction side of the compressor 3, and the temperature sensor 13j is provided between the internal heat exchanger 14 and the second expansion valve 10, respectively. Measure the refrigerant temperature. The temperature sensor 13f measures the outside air temperature around the outdoor unit 1.

  Temperature sensors 13g, 13h, and 13i are installed in the indoor unit 2. The temperature sensor 13g is on the refrigerant flow path in the middle of the indoor heat exchanger 6, and the temperature sensor 13h is between the indoor heat exchanger 6 and the liquid pipe 7. The refrigerant temperature at each installation location is measured. The temperature sensor 13 i measures the temperature of the air taken into the indoor heat exchanger 6. When the heat medium serving as a load is another medium such as water, the temperature sensor 13i measures the inflow temperature of the medium.

  The temperature sensors 13b and 13g can detect the refrigerant saturation temperature at high and low pressure by detecting the refrigerant temperature in a gas-liquid two-phase state in the middle of the heat exchanger.

  In addition, the measurement control device 12 in the outdoor unit 1 is based on the measurement information of the temperature sensor 13 and the operation content instructed by the user of the refrigeration air conditioner, the operation method of the compressor 3, the flow path switching of the four-way valve 4, The fan air flow rate of the outdoor heat exchanger 11, the opening degree of each expansion valve, and the like are controlled. The measurement control device 12 functions as an arithmetic processing unit of the heat exchange amount detection means 12a, the superheat degree detection means 12b, and the target superheat degree calculation means 12c as in the case of the first embodiment. In addition, the supercooling degree detection means 12d also functions as an arithmetic processing unit. The supercooling degree detection means 12d of the present invention is composed of a temperature sensor 13b and a temperature sensor 13c (or a temperature sensor 13g and a temperature sensor 13h) and a measurement control device 12, and during the cooling operation, the temperature sensor 13b and the temperature sensor 13c The degree of supercooling is obtained based on the output, and the degree of supercooling is obtained based on the outputs of the temperature sensor 13g and the temperature sensor 13h during the heating operation.

Next, the operation of this refrigeration air conditioner will be described.
First, the operation during the cooling operation will be described based on the Ph diagrams shown in FIGS. 4 and 5. During the cooling operation, the flow path of the four-way valve 4 is set in the direction of the solid line in FIG. The high-temperature and high-pressure gas refrigerant (point 1 in FIG. 5) discharged from the compressor 3 flows into the outdoor heat exchanger 11 serving as a condenser through the four-way valve 4, where it condenses and liquefies while dissipating heat, and becomes a high-pressure and low-temperature refrigerant. (Point 2 in FIG. 5). The refrigerant exiting the outdoor heat exchanger 11 is slightly decompressed by the first expansion valve 10 (point 3 in FIG. 5), and then is cooled by the internal heat exchanger 14 by exchanging heat with the refrigerant sucked into the compressor 3. (Fig. 5, point 4). Thereafter, the pressure is reduced to a low pressure by the second expansion valve 8 to become a two-phase refrigerant (point 5 in FIG. 5), then flows out of the outdoor unit 1 and flows into the indoor unit 2 through the liquid pipe 7. And it flows in the indoor heat exchanger 6 used as an evaporator, absorbs heat there, and supplies cold heat to a load side medium such as air or water on the indoor unit 2 side while evaporating gas (6 in FIG. 5). The low-pressure gas refrigerant exiting the indoor heat exchanger 6 exits the indoor unit 2, flows into the outdoor unit 1 through the gas pipe 5, passes through the four-way valve 4, and then exchanges heat with the high-pressure refrigerant in the internal heat exchanger 14. After being heated (point 7 in FIG. 5), it is sucked into the compressor 3, compressed to a high pressure and discharged (point 1 in FIG. 5).

  Next, the operation during heating operation will be described based on the Ph diagrams shown in FIGS. During the heating operation, the flow path of the four-way valve 4 is set in the direction of the dotted line in FIG. The high-temperature and high-pressure gas refrigerant (point 1 in FIG. 5) discharged from the compressor 3 flows out of the outdoor unit 1 through the four-way valve 4 and flows into the indoor unit 2 through the gas pipe 5. Then, the refrigerant flows into the indoor heat exchanger 6 and is condensed and liquefied while radiating heat in the indoor heat exchanger 6 serving as a condenser to be a high-pressure and low-temperature liquid refrigerant (point 2 in FIG. 5). Heating is performed by applying heat radiated from the refrigerant to a load-side medium such as air or water on the load side. The high-pressure and low-temperature refrigerant that has exited the indoor heat exchanger 6 flows into the outdoor unit 1 via the liquid pipe 7, and after being slightly depressurized by the second expansion valve 8 (point 3 in FIG. 5), The heat exchanger 14 heats and cools the low-temperature refrigerant sucked by the compressor 3 (point 4 in FIG. 5). Then, the pressure is reduced to a low pressure by the first expansion valve 10 to become a two-phase refrigerant (point 5 in FIG. 5), and then flows into the outdoor heat exchanger 11 serving as an evaporator, where heat is absorbed and evaporated and gasified (point 6 in FIG. 5). ). After that, the heat is exchanged with the high-pressure refrigerant in the internal heat exchanger 14 through the four-way valve 4 and further heated (point 7 in FIG. 5), sucked into the compressor 3 and compressed and discharged to the high pressure (point 1 in FIG. 5). Thus, the Ph diagram during heating operation is substantially the same as during cooling operation, and the same operation can be realized in either operation mode.

  Next, the control operation during the cooling operation will be described. During the cooling operation, first, the capacity of the compressor 3, the opening of the first expansion valve 10, and the opening of the second expansion valve 8 are set to initial values. Thereafter, each actuator according to the operating state is controlled as follows. The capacity of the compressor 3 is basically controlled so that the air temperature measured by the temperature sensor 13 i of the indoor unit 2 becomes a temperature set by the user of the refrigeration air conditioner. Therefore, when the air temperature is higher than the set temperature, the capacity of the compressor 3 is increased. When the air temperature is close to the set temperature, the capacity of the compressor 3 is maintained as it is. When the temperature is lower than the set temperature, the capacity of the compressor 3 is reduced.

  Each expansion valve is controlled as follows. First, the first expansion valve 10 is a refrigerant at the outlet of the outdoor heat exchanger 11 that is obtained by the difference between the saturation temperature of the high-pressure refrigerant detected by the temperature sensor 13b and the outlet temperature of the outdoor heat exchanger 11 detected by the temperature sensor 13c. The supercooling degree SC is controlled to be a preset target value, for example, 10 ° C. The refrigerant supercooling degree SC is obtained by the measurement control device 12 (supercooling degree detection means 12d) based on the outputs of the temperature sensor 13b and the temperature sensor 13c. When the refrigerant supercooling degree SC is larger than the target value, the opening degree of the first expansion valve 10 is large, and when the refrigerant subcooling degree SC is smaller than the target value, the opening degree of the first expansion valve 10 is controlled to be small. Is done.

  Next, the second expansion valve 8 uses the temperature difference between the compressor 3 suction temperature detected by the temperature sensor 13e and the saturation temperature of the low-pressure refrigerant detected by the temperature sensor 13g. The SH is controlled to be a preset target value, for example, 10 ° C. When the refrigerant superheat degree SH is larger than the target value, the opening degree of the third expansion valve 8 is large, and when the refrigerant superheat degree SH is smaller than the target value, the opening degree of the second expansion valve 8 is controlled to be small. .

  Here, the target value of the superheat degree of the refrigerant sucked by the compressor 3 as the control target of the second expansion valve 8 is the indoor heat of the indoor unit 2 serving as an evaporator according to the heat exchange amount in the internal heat exchanger 14 as described above. By calculating so that the outlet refrigerant state of the exchanger 6 becomes a dryness degree 1 that is a saturated gas state, even when the internal heat exchange amount changes due to a change in the operation state or the like, the highly efficient operation is continuously performed. be able to.

  The target value of the refrigerant 3 suction refrigerant superheat degree during the cooling operation is determined by using the output of the temperature sensor 13c (outlet temperature information of the outdoor unit heat exchanger) and the high-pressure refrigerant inlet enthalpy of the internal heat exchanger 14 ( The first enthalpy is calculated, the high pressure refrigerant outlet enthalpy (second enthalpy) is calculated from the temperature sensor 13d (external refrigerant temperature information of the internal heat exchanger), and the enthalpy of the high pressure refrigerant inlet enthalpy and the high pressure refrigerant outlet enthalpy. The difference (Δh) is calculated. Then, the constant pressure specific heat (Cp) in the saturated gas state is calculated from the output of the temperature sensor 13g (temperature information of the indoor unit heat exchanger), and the indoor heat exchanger is based on the enthalpy difference (Δh) and the constant pressure specific heat (Cp). The degree of superheated gas in a state where the dryness of the outlet refrigerant of 6 is 1 is calculated and set as a target value.

  Next, the heating operation control operation in this refrigeration air conditioner will be described. During the heating operation, first, the capacity of the compressor 3, the opening of the first expansion valve 10, and the opening of the second expansion valve 8 are set to initial values. Thereafter, each actuator corresponding to the operating state is controlled as follows. The capacity of the compressor 3 is basically controlled so that the air temperature measured by the temperature sensor 13 i of the indoor unit 2 becomes a temperature set by the user of the refrigeration air conditioner. Accordingly, when the air temperature is greatly lower than the set temperature, the capacity of the compressor 3 is increased. When the air temperature is close to the set temperature, the capacity of the compressor 3 is maintained as it is, and the air When the temperature is higher than the set temperature, the capacity of the compressor 3 is reduced.

  Each expansion valve is controlled as follows. First, the second expansion valve 8 is a refrigerant at the outlet of the indoor heat exchanger 6 that is obtained by the temperature difference between the saturation temperature of the high-pressure refrigerant detected by the temperature sensor 13g and the outlet temperature of the indoor heat exchanger 6 detected by the temperature sensor 13h. The supercooling degree SC is controlled to be a preset target value, for example, 10 ° C. The refrigerant supercooling degree SC is obtained by the measurement control device 12 (supercooling degree detection means 12d) based on the outputs of the temperature sensor 13g and the temperature sensor 13h. When the refrigerant supercooling degree SC is larger than the target value, the opening degree of the second expansion valve 8 is large, and when the refrigerant subcooling degree SC is smaller than the target value, the opening degree of the second expansion valve 8 is controlled to be small. Is done.

  Next, the first expansion valve 10 has the refrigerant 3 superheated in the compressor 3 detected by the temperature difference between the compressor 3 suction temperature detected by the temperature sensor 13e and the saturation temperature of the low-pressure refrigerant detected by the temperature sensor 13b. The degree SH is controlled to be a preset target value, for example, 10 ° C. When the refrigerant superheat degree SH is larger than the target value, the opening degree of the first expansion valve 10 is large, and when the refrigerant superheat degree SH is smaller than the target value, the opening degree of the first expansion valve 10 is made small.

  Here, the target value of the refrigerant superheating degree of the suction of the compressor 3 which is a control target of the first expansion valve 10 is the outdoor unit 1 which becomes an evaporator from the heat exchange amount in the internal heat exchanger 14 as described above. By calculating so that the outlet refrigerant state of the outdoor heat exchanger 11 becomes a dryness degree 1 that is a saturated gas state, even when the internal heat exchange amount changes due to a change in the operation state or the like, high-efficiency operation continues. You can do it.

  The target value of the refrigerant 3 suction refrigerant superheat degree during the heating operation is determined by using the output of the temperature sensor 13h (the outlet refrigerant temperature information of the indoor unit heat exchanger), and the high-pressure refrigerant inlet enthalpy of the internal heat exchanger 14. (First enthalpy) is calculated, the high pressure refrigerant outlet enthalpy (second enthalpy) is calculated from the temperature sensor 13j (external refrigerant temperature information of the internal heat exchanger), and the high pressure refrigerant inlet enthalpy and the high pressure refrigerant outlet enthalpy are calculated. The enthalpy difference (Δh) is calculated. Then, the constant pressure specific heat (Cp) in the saturated gas state is calculated from the output of the temperature sensor 13b (temperature information of the outdoor heat exchanger), and the outdoor heat is calculated based on the enthalpy difference (Δh) and the constant pressure specific heat (Cp). The superheated gas degree in a state where the dryness of the outlet refrigerant of the exchanger 11 is 1 is calculated and set as a target value.

  Next, functions and effects realized by the circuit configuration and control of the present embodiment will be described. In the refrigerating and air-conditioning apparatus according to the second embodiment, the same effect can be obtained in both cooling and heating operations, and high-efficiency operation can be continued. Moreover, by setting it as this Embodiment, the enthalpy of an internal heat exchanger entrance refrigerant | coolant can be calculated reliably by controlling the refrigerant | coolant state of a condenser exit to a supercooled state.

Embodiment 3 FIG.
A third embodiment of the present invention is shown in FIG. FIG. 6 is a refrigerant circuit diagram of the refrigerating and air-conditioning apparatus according to Embodiment 3. In the outdoor unit 1, an intermediate pressure receiver with an internal heat exchange function (hereinafter referred to as an intermediate pressure receiver) 9 is provided, and the compressor 3 is provided therein. The suction pipe penetrates. The refrigerant in the penetrating portion and the refrigerant in the intermediate pressure receiver 9 are configured to exchange heat, and realize the same function as the internal heat exchanger 14 in the first and second embodiments.

  Since the operation in this embodiment is the same as that in the second embodiment except for the intermediate-pressure receiver 9, the description thereof is omitted. In the intermediate pressure receiver 9, the gas-liquid two-phase refrigerant at the outlet of the first expansion valve 10 flows in during the cooling operation, and is cooled in the intermediate pressure receiver 9 and flows out as liquid. During the heating operation, the gas-liquid two-phase refrigerant that has exited the second expansion valve 8 flows in, cools in the intermediate pressure receiver 9, and flows out as liquid. The heat exchange in the intermediate pressure receiver 9 is mainly performed by exchanging the gas refrigerant out of the gas-liquid two-phase refrigerant into contact with the suction pipe to be condensed and liquefied. Therefore, the smaller the amount of liquid refrigerant staying in the intermediate pressure receiver 9, the more the area where the gas refrigerant and the suction pipe are in contact with each other, and the amount of heat exchange increases. On the contrary, when the amount of liquid refrigerant staying in the intermediate pressure receiver 9 is large, the area where the gas refrigerant and the suction pipe are in contact with each other decreases, and the amount of heat exchange decreases.

  By providing the intermediate pressure receiver 9 as described above, the following effects are obtained. First, since the outlet of the intermediate pressure receiver 9 is liquid, the refrigerant flowing into the second expansion valve 8 during the cooling operation is necessarily liquid refrigerant, so that the flow rate characteristic of the second expansion valve 8 is stable and control stability is improved. Secured and stable device operation can be performed.

  Since the outlet of the intermediate pressure receiver 9 is in a saturated liquid state unless the inside of the intermediate pressure receiver 9 is filled with the liquid refrigerant, the temperature sensor 13d is installed at a position where the saturated liquid temperature can be detected at the lower part of the receiver. In both cases of operation and heating operation, the refrigerant pressure at the outlet of the intermediate pressure receiver 9 can be detected, so that it is possible to use both by installing one temperature sensor.

  In addition, as long as the structure which performs heat exchange with the intermediate pressure receiver 9 is a structure which heat-exchanges with the refrigerant | coolant in the intermediate pressure receiver 9, what kind of structure can take the same effect. For example, you may use the structure which makes the suction | inhalation piping of the compressor 3 contact the outer periphery of the container of the intermediate pressure receiver 9, and heat-exchanges.

  In the third embodiment, the internal heat exchanger 14 of the second embodiment is replaced with the intermediate pressure receiver 9, but the internal heat exchanger 14 of the first embodiment may be replaced with the intermediate pressure receiver 9. Similar effects can be obtained.

Embodiment 4 FIG.
An evaporator of a general refrigeration cycle has multiple passes in order to reduce refrigerant pressure loss in the heat exchanger, and uses decompression adjusting means such as capillaries for adjusting the refrigerant flow rate for each pass. However, if it is attempted to control the evaporator outlet state to a saturated gas state with a dryness of 1, depending on the path, the refrigerant may be in an overheated gas state due to insufficient circulation amount, resulting in a state where heat transfer performance is degraded. In such a state, the balance of the refrigerant flow rate for each pass, the so-called pass balance, is lost, and eventually the performance is reduced. In addition, when such a situation occurs, the indoor air that passes around the heat transfer tube that has become superheated gas is not dehumidified, and therefore passes through the evaporator heat exchanger in a high humidity state. This may cause condensation at the air outlet and cause water droplets to drop and scatter in the indoor space, which may cause so-called dew, which may impair reliability. Therefore, in order to prevent such problems, it may be desirable to control the evaporator outlet refrigerant state in a wet state in which the dryness is slightly lower than 1 (0.9 to 1.0). As a specific method, a value that is 1 to 2 ° C. lower than the target refrigerant superheat value calculated from the heat exchange amount in the intermediate pressure receiver 9 described above may be used as the control target value.

  For example, taking the cooling operation of the third embodiment as an example, the outdoor unit heat exchanger (condenser) 11 outlet temperature sensor 13c = 41.0 [° C.], the intermediate pressure receiver temperature sensor 13d = 37.5 [° C.], In the case of the refrigerant circulation amount Gr = 220 [kg / h], the internal heat exchanger heat exchange amount Q is Q = Δh × Gr = 6.47 [kJ / kg] × 220 [kg / h] = 1423.3 [kJ / h] On the other hand, when the temperature sensor 13g = 11.5 [° C.], Cpa = 1.24 [kJ / kg · ° C.], so the compressor when the evaporator outlet refrigerant is in a saturated gas state 3 The suction refrigerant superheat degree SHm is SHm = Q / Gr / Cpa = 5.2 [° C.]. Therefore, when the evaporator outlet refrigerant state is controlled to a saturated gas state with a dryness of 1, the target excess that is the control target of the expansion valve may be set to 5.2 ° C. Here, when the target superheat degree of the expansion valve is set to 4 ° C., the evaporator outlet dryness = 0.99, and when the target superheat degree is 3 ° C., the evaporator outlet dryness = 0.98. .

  In this way, the target evaporator dryness may be changed according to the surrounding environment or the like. That is, when there is a concern about condensation or dew on the evaporator due to high humidity conditions, the evaporator outlet dryness should be less than 1, and when low humidity conditions or high efficiency operation is desired, the evaporator outlet dryness should be set to 1. You can do it.

Focusing on the outdoor unit 1 of the above-described Embodiments 2 and 3, the outdoor unit 1 receives necessary temperature information (temperature sensors 13g, 13h, 13i) from the indoor unit 2, and therefore, the indoor unit 2 Regardless of the form, a highly efficient operation can be realized similarly.
Moreover, since the outdoor unit 1 has received the necessary temperature information from the indoor unit 2, it is possible to realize a highly reliable operation that avoids problems such as dewdrops, regardless of the form of the indoor unit 2. it can.
Further, when paying attention to the measurement control device 12 of the refrigeration and air-conditioning apparatus according to the first to third embodiments, the measurement control device 12 can be used even when the indoor unit 2 or the outdoor unit 1 is replaced due to equipment failure or the like. By diverting, a highly efficient operation can be realized in the same manner, and a highly reliable operation that avoids problems such as dewdrops can be realized.

  In the first to third embodiments, the example of R410A has been described as the refrigerant of the refrigeration air conditioner. However, the refrigerant is not limited to R410A and can be used for other refrigerants.

  In the first to third embodiments, the example in which the saturation temperature of the refrigerant is detected by the refrigerant temperature sensor (13k, 13n / 13b, 13g) between the condenser and the evaporator has been described. A pressure sensor may be provided, and the saturation pressure may be obtained by converting the measured pressure value.

  In the first to third embodiments, examples of calculating enthalpy and constant pressure specific heat based on the refrigerant temperature have been described. For this calculation, for example, an arithmetic expression corresponding to the refrigerant used is measured in advance. It is assumed that arithmetic processing is performed by providing the microcomputer incorporated in the control device 12.

1 is a refrigerant circuit diagram of a refrigerating and air-conditioning apparatus showing a first embodiment of the present invention. It is a Ph diagram showing the operating condition of the refrigerating and air-conditioning apparatus according to the first embodiment of the present invention. It is a figure which shows the relationship between an evaporator exit dryness and evaporator capability. It is a refrigerant circuit figure of the refrigerating and air-conditioning apparatus which shows 2nd Embodiment of this invention. It is a Ph diagram showing the operating condition of the refrigerating and air-conditioning apparatus according to the second embodiment of the present invention. It is a refrigerant circuit figure of the refrigerating and air-conditioning apparatus which shows the 3rd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Outdoor unit, 2 Indoor unit, 3 Compressor, 4 Four way valve, 5 Gas pipe, 6 Indoor heat exchanger, 7 Liquid pipe, 8 2nd expansion valve, 9 Medium pressure receiver with internal heat exchange function, 10 1st expansion Valve, 11 Outdoor heat exchanger, 12 Measurement control device, 12a Heat quantity detection means, 12b Superheat degree detection means, 12c Target superheat degree calculation means, 12d Supercooling degree detection means, 13a, 13b, 13c, 13d, 13e, 13f , 13g, 13h, 13i, 13j, 13k, 13l, 13m, 13n, 13o, 13p Temperature sensor, 14 Internal heat exchanger, 15 Heat exchanger for condenser, 16 Heat exchanger for evaporator.

Claims (7)

In the refrigeration air conditioner in which the compressor, the condenser, the first decompressor, the second decompressor, and the evaporator are connected in an annular shape,
An internal heat exchanger for exchanging heat between the refrigerant between the first pressure reducing device and the second pressure reducing device, and the refrigerant between the evaporator and the compressor;
Supercooling degree detecting means for detecting the supercooling degree of the refrigerant at the outlet of the condenser;
First control means for adjusting the flow rate of the first pressure reducing device so that the degree of supercooling detected by the degree of supercooling detection means becomes a predetermined value;
A heat exchange amount detecting means for detecting a heat exchange amount in the internal heat exchanger;
Superheat degree detection means for detecting the superheat degree of the refrigerant at the compressor inlet after being heated by the internal heat exchanger;
Target superheat degree calculating means for calculating the superheat degree of the refrigerant at the compressor inlet when the refrigerant at the evaporator outlet is in a saturated gas state from the internal heat exchange amount detected by the heat exchange amount detecting means;
The superheat degree calculated by the target superheat degree calculation means is set as the target superheat degree, and the superheat degree of the refrigerant at the compressor inlet detected by the superheat degree detection means is adjusted so as to approach the target superheat degree. A second control device for adjusting the flow rate ,
The heat exchange amount detection means includes
A first enthalpy of the internal heat exchanger inlet refrigerant of the high temperature side refrigerant is calculated based on the refrigerant temperature information of the condenser outlet, and a high temperature side is calculated based on the refrigerant temperature information of the high temperature side refrigerant of the internal heat exchanger outlet A second enthalpy of the refrigerant at the outlet of the internal heat exchanger of the refrigerant is calculated, an enthalpy difference (Δh) between the first enthalpy and the second enthalpy is calculated, and based on the enthalpy difference (Δh) Calculating the amount of heat exchange (Q) in the internal heat exchanger,
The target superheat degree calculating means includes
The constant pressure specific heat (Cp) in the saturated gas state of the refrigerant is obtained based on the refrigerant temperature information in the evaporator, and the heat exchange amount (Q) and the constant pressure specific heat (Cp at the inlet of the internal heat exchanger of the low temperature side refrigerant). ) To calculate the degree of superheat of the refrigerant at the inlet of the compressor . The internal heat exchanger includes a receiver disposed between the first pressure reducing device and the second pressure reducing device, a refrigerant in the receiver, and a refrigerant between the evaporator and the compressor refrigerating and air-conditioning apparatus according to claim 1, wherein the heat exchange. The refrigerating and air-conditioning apparatus according to claim 1 or 2, wherein a target value of the dryness of the refrigerant at the outlet of the evaporator is made smaller than 1 . In an outdoor unit of a refrigeration air conditioner equipped with a compressor, a four-way valve, an outdoor heat exchanger, a first pressure reducing device, and a second pressure reducing device,
An internal heat exchanger for exchanging heat between the refrigerant between the first pressure reducing device and the second pressure reducing device and the refrigerant between the four-way valve and the compressor;
During cooling operation, the intermediate refrigerant temperature and outlet refrigerant temperature of the outdoor heat exchanger are used, and during heating operation, the intermediate refrigerant temperature and outlet refrigerant temperature of the indoor heat exchanger sent from the indoor unit are used. , A supercooling degree detecting means for detecting a supercooling degree of the outlet refrigerant of the compressor,
A first controller that adjusts the flow rate of the first pressure reducing device so that the degree of supercooling becomes a predetermined value;
A heat exchange amount detecting means for detecting a heat exchange amount in the internal heat exchanger;
Superheat degree detection means for detecting the superheat degree of the refrigerant at the compressor inlet after being heated by the internal heat exchanger;
Target superheat degree calculating means for calculating the superheat degree of the refrigerant at the compressor inlet when the refrigerant at the evaporator outlet is in a saturated gas state from the internal heat exchange amount detected by the heat exchange amount detecting means;
The superheat degree calculated by the target superheat degree calculation means is set as the target superheat degree, and the flow rate adjustment of the second pressure reducing device is performed so that the compressor inlet superheat degree detected by the superheat degree detection means becomes the target superheat degree. A second control device to perform ,
The heat exchange amount detection means includes
Calculate the high-pressure refrigerant inlet enthalpy of the internal heat exchanger using the outlet temperature information of the indoor heat exchanger during heating operation and the outlet refrigerant temperature information of the outdoor heat exchanger during cooling operation, respectively, The high pressure refrigerant outlet enthalpy is calculated from the outlet refrigerant temperature information of the heat exchanger, the enthalpy difference (Δh) between the high pressure refrigerant inlet enthalpy and the high pressure refrigerant outlet enthalpy is calculated, and based on the enthalpy difference (Δh) Calculate the amount of heat exchange (Q) in the internal heat exchanger,
The target superheat degree calculating means includes
From the temperature information of the indoor heat exchanger during the cooling operation, and from the temperature information of the outdoor heat exchanger during the heating operation, the constant pressure specific heat (Cp) in the saturated gas state is calculated.
The degree of superheated gas in a state where the dryness of the refrigerant at the outlet of the evaporator is a predetermined value is calculated based on the heat exchange amount (Q) and the constant pressure specific heat (Cp). Air conditioner outdoor unit. The target value of the dryness of the refrigerant at the outlet of the indoor heat exchanger is made smaller than 1 during the cooling operation, and the target value of the dryness of the refrigerant at the outlet of the outdoor heat exchanger is made smaller than 1 during the heating operation. The outdoor unit of the refrigerating and air-conditioning apparatus according to claim 4 . A compressor, an outdoor heat exchanger, a first pressure reducing device, an internal heat exchanger, a second pressure reducing device, and an indoor heat exchanger are connected in a ring shape, and between the first pressure reducing device and the second pressure reducing device. In the control device for a refrigeration air conditioner comprising an internal heat exchanger for exchanging heat between the refrigerant and the refrigerant between the indoor heat exchanger and the compressor,
(A) Supercooling of the outlet refrigerant of the condenser from the intermediate refrigerant temperature and outlet refrigerant temperature information of the indoor heat exchanger during heating operation, and from the intermediate temperature and outlet temperature information of the outdoor heat exchanger during cooling operation The flow rate is adjusted by the first pressure reducing device so that the value approaches a predetermined target value,
(B) Using the outlet temperature information of the indoor heat exchanger during the heating operation and the outlet refrigerant temperature information of the outdoor heat exchanger during the cooling operation, the high pressure refrigerant inlet enthalpy of the internal heat exchanger is calculated. , Calculating the high-pressure refrigerant outlet enthalpy from the outlet refrigerant temperature information of the internal heat exchanger, calculating the enthalpy difference (Δh) between the high-pressure refrigerant inlet enthalpy and the high-pressure refrigerant outlet enthalpy,
(C) The constant pressure specific heat (Cp) in the saturated gas state is calculated from the temperature information of the indoor heat exchanger during the cooling operation and from the temperature information of the outdoor heat exchanger during the heating operation,
(D) Based on the enthalpy difference (Δh) and the constant pressure specific heat (Cp), calculate the superheated gas degree in a state where the dryness of the outlet refrigerant of the evaporator becomes a predetermined value,
(E) The superheated gas degree is set as a control target value of the second decompression device, and from the refrigerant refrigerant temperature information and the temperature information of the indoor heat exchanger during the cooling operation, the outdoor heat during the heating operation. A refrigerating and air-conditioning apparatus that calculates the degree of superheat of refrigerant at the compressor inlet from the temperature information of the exchanger and adjusts the flow rate of the second decompression device so that the value becomes the target value. Control device. During the cooling operation, the target superheat degree is set by setting the target value of the dryness of the outlet refrigerant of the indoor heat exchanger to be smaller than 1.
The control device for a refrigerating and air-conditioning apparatus according to claim 6, wherein the target superheat degree is set by setting a target value of a dryness degree of an outlet refrigerant of the outdoor heat exchanger to be smaller than 1 during a heating operation.

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