EP3862649A1 - Appareil à cycle frigorifique - Google Patents

Appareil à cycle frigorifique Download PDF

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Publication number
EP3862649A1
EP3862649A1 EP18936213.0A EP18936213A EP3862649A1 EP 3862649 A1 EP3862649 A1 EP 3862649A1 EP 18936213 A EP18936213 A EP 18936213A EP 3862649 A1 EP3862649 A1 EP 3862649A1
Authority
EP
European Patent Office
Prior art keywords
refrigerant
economizer
intercooler
expansion valve
circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP18936213.0A
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German (de)
English (en)
Other versions
EP3862649A4 (fr
Inventor
Shun Okada
Masahiro Kanda
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Publication date
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Publication of EP3862649A1 publication Critical patent/EP3862649A1/fr
Publication of EP3862649A4 publication Critical patent/EP3862649A4/fr
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2500/00—Problems to be solved
    • F25B2500/19—Calculation of parameters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/25—Control of valves
    • F25B2600/2509—Economiser valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/19—Pressures
    • F25B2700/195—Pressures of the condenser
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2116—Temperatures of a condenser
    • F25B2700/21163—Temperatures of a condenser of the refrigerant at the outlet of the condenser
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2117—Temperatures of an evaporator
    • F25B2700/21175—Temperatures of an evaporator of the refrigerant at the outlet of the evaporator

Definitions

  • the present disclosure relates to a refrigeration cycle apparatus including a refrigerant circuit through which refrigerant is circulated.
  • Patent Literature 1 discloses a refrigeration apparatus including an economizer circuit through which part of refrigerant flowing out from a condenser is injected into a compressor via an intermediate heat exchanger and an economizer expansion valve disposed in the economizer circuit.
  • This refrigeration apparatus includes, as an economizer expansion valve, a thermostatic expansion valve and adjusts the opening degree of the economizer expansion valve to keep the degree of superheat of the intermediate heat exchanger constant.
  • Patent Literature 1 Japanese Patent No. 5463192
  • Patent Literature 1 adjusts the opening degree of the economizer expansion valve such that the degree of superheat of the intermediate heat exchanger is kept constant.
  • its annual efficiency which is an annual COP evaluation index, cannot be expected to improve.
  • the present disclosure has been made to solve the above-described problem and aims to provide a refrigeration cycle apparatus that improves annual efficiency.
  • a refrigeration cycle apparatus includes a refrigerant circuit in which a compressor, a condenser, an intercooler, a main expansion valve, and an evaporator are connected by a refrigerant pipe and through which refrigerant is circulated; an economizer circuit branching off from the refrigerant circuit between the intercooler and the main expansion valve or between the condenser and the intercooler and connecting to the compressor via the intercooler; an economizer expansion valve disposed in the economizer circuit; an intermediate pressure sensor disposed in the economizer circuit and configured to detect an intermediate pressure of the refrigerant to be injected into the compressor; a temperature sensor disposed in the economizer circuit and configured to detect a temperature of the refrigerant to be injected into the compressor; a calculating unit configured to calculate an economizer superheat degree that is a difference between a saturated gas temperature corresponding to the intermediate pressure detected by the intermediate pressure sensor and a detection value of the temperature sensor and
  • a refrigeration cycle apparatus includes a refrigerant circuit in which a compressor, a condenser, an intercooler, a main expansion valve, and an evaporator are connected by a refrigerant pipe and through which refrigerant is circulated; an economizer circuit branching off from the refrigerant circuit between the intercooler and the main expansion valve or between the condenser and the intercooler and connecting to the compressor via the intercooler; an economizer expansion valve disposed in the economizer circuit; an intermediate pressure sensor disposed in the economizer circuit and configured to detect an intermediate pressure of the refrigerant to be injected into the compressor; an intercooler high-pressure side outlet temperature sensor disposed between the intercooler and the main expansion valve in the refrigerant circuit and configured to detect a temperature of the refrigerant; a calculating unit configured to calculate a main refrigerant liquid approach temperature that is a difference between a saturated gas temperature corresponding to the intermediate pressure detected by the intermediate pressure
  • the target value of a monitored target is set such that a higher COP is achieved at an actual operating load.
  • the opening degree of the economizer expansion valve is thus adjusted more appropriately than in a case where the target value is set to be constant. Annual efficiency is therefore improved.
  • FIG. 1 is a refrigerant circuit diagram illustrating an example of the refrigeration cycle apparatus according to Embodiment 1 of the present disclosure.
  • a refrigeration cycle apparatus 1 includes a compressor 2, a condenser 3, an intercooler 4, a main expansion valve 5, an evaporator 6, an economizer circuit 11, and a controller 10.
  • the intercooler 4 includes a high pressure section 4a and a low pressure section 4b.
  • the compressor 2, the condenser 3, the high pressure section 4a of the intercooler 4, the main expansion valve 5, and the evaporator 6 are connected by a refrigerant pipe.
  • a refrigerant circuit 12 through which refrigerant is circulated is thus formed.
  • An evaporating pressure sensor 8a is disposed to a refrigerant outlet of the evaporator 6.
  • the evaporating pressure sensor 8a detects an evaporating pressure of the refrigerant flowing out from the evaporator 6.
  • a condensing pressure sensor 8b is disposed to a refrigerant inlet of the condenser 3.
  • the condensing pressure sensor 8b detects a condensing pressure of the refrigerant flowing into the condenser 3.
  • the compressor 2 suctions, compresses, and discharges the refrigerant.
  • the compressor 2 is an inverter-driven compressor whose capacity can be changed by adjusting a rotational frequency. Examples of the compressor 2 include a single-screw compressor and a twin-screw compressor.
  • the compressor 2 may be of any compressor to which the economizer circuit 11 can be connected.
  • the condenser 3 is a heat exchanger that exchanges heat between gas refrigerant discharged from the compressor 2 and, for example, air or water, to cool and condense the gas refrigerant.
  • the evaporator 6 is a heat exchanger that exchanges heat between the refrigerant flowing out from the main expansion valve 5 and, for example, air, water, or brine, to evaporate the refrigerant.
  • the condenser 3 and the evaporator 6 are, for example, fin- and-tube heat exchangers, plate heat exchangers, or shell-and-tube heat exchangers.
  • the main expansion valve 5 reduces the pressure of the refrigerant flowing from the intercooler 4 to expand the refrigerant.
  • the main expansion valve 5 is, for example, an electronic expansion valve.
  • the economizer circuit 11 includes an economizer pipe 9 that branches off from the refrigerant circuit between the intercooler 4 and the main expansion valve 5 and connects to the compressor 2 via the low pressure section 4b of the intercooler 4 and an economizer expansion valve 7 disposed in the economizer pipe 9.
  • the economizer expansion valve 7 is disposed between the intercooler 4 and a branch point 15 located between the intercooler 4 and the main expansion valve 5.
  • the economizer expansion valve 7 is, for example, an electronic expansion valve.
  • a temperature sensor 13 and an intermediate pressure sensor 8c are arranged between the intercooler 4 and the compressor 2.
  • the intercooler 4 includes the high pressure section 4a and the low pressure section 4b.
  • the refrigerant on a high-pressure side between the condenser 3 and the main expansion valve 5, or high-pressure side refrigerant flows through the high pressure section 4a.
  • the economizer expansion valve 7 reduces the pressure of part of the high-pressure side refrigerant, and the part of the refrigerant flows through the low pressure section 4b.
  • the refrigerant flowing out from the low pressure section 4b is refrigerant having an intermediate pressure in the entire refrigeration cycle, or intermediate pressure refrigerant.
  • the intercooler 4 exchanges heat between the high-pressure side refrigerant and the intermediate pressure refrigerant to cool the high-pressure side refrigerant.
  • the temperature sensor 13 detects the temperature of the refrigerant to be injected into the compressor 2.
  • the intermediate pressure sensor 8c detects the intermediate pressure of the refrigerant to be injected to the compressor 2.
  • Fig. 2 is a functional block diagram illustrating an exemplary configuration of the controller in Fig. 1 .
  • the controller 10 incudes a memory 31 storing a program and a central processing unit (CPU) 32 that executes a process in accordance with the program.
  • CPU central processing unit
  • a refrigeration cycle control unit 33, a calculating unit 34, and a flow rate control unit 35 are involved in the refrigeration cycle apparatus 1 as illustrated in Fig. 2 .
  • the refrigeration cycle control unit 33 adjusts the rotational frequency of the compressor 2 and the opening degree of the main expansion valve 5 on the basis of detection values of the evaporating pressure sensor 8a and the condensing pressure sensor 8b.
  • the calculating unit 34 calculates, as a monitored target in economizer flow rate control, an economizer superheat degree ⁇ Tesh that is the difference between a saturated gas temperature Tesa corresponding to the intermediate pressure and a refrigerant temperature Te detected by the temperature sensor 13. Furthermore, the calculating unit 34 determines a target value of the economizer superheat degree ⁇ Tesh on the basis of an operating state of the refrigerant circuit 12.
  • the calculating unit 34 determines a target value on the basis of, as an operating state of the refrigerant circuit 12, a compression ratio of the compressor 2, the operating state of the refrigerant circuit 12 used as the basis to determine the target value is not limited to the compression ratio.
  • the calculating unit 34 calculates the compression ratio of the compressor 2 from an evaporating pressure detected by the evaporating pressure sensor 8a and a condensing pressure detected by the condensing pressure sensor 8b.
  • the flow rate control unit 35 adjusts the opening degree of the economizer expansion valve 7 such that the economizer superheat degree ⁇ Tesh, which is a monitored target, matches the target value.
  • a COP at a rated condition has been mainly used as an index of energy conservation in a refrigeration cycle apparatus.
  • the rated condition is an operating condition at 100% operating load. Attention has recently been focused on annual efficiencies as indices close to actual operating conditions. Examples of the annual efficiencies include an integrated part load value (IPLV).
  • IPLV integrated part load value
  • IPLV US 0.01 ⁇ A + 0.42 ⁇ B + 0.45 ⁇ C + 0.12 ⁇ D
  • A is a COP at 100% load
  • B is a COP at 75% load
  • C is a COP at 50% load
  • D is a COP at 25% load.
  • the integrated part load value is calculated by summing multiple COPs associated with different operating loads.
  • the coefficient of each term represents a ratio to annual operating time. For example, when Tz denotes the annual operating time, operating time at 100% operating load is 0.01 ⁇ Tz (hour). Each coefficient is a weight for the operating load in the annual operating time. With reference to Expression (1), operating time at 75% load accounts for 42% of the annual operating time and operating time at 50% load accounts for 45% of the annual operating time. In Expression (1), greater weights are assigned to these two operating conditions.
  • JRAIA Japan Refrigeration and Air Conditioning Industry Association
  • IPLV us an integrated part load value, which is an index similar to American integrated part load value IPLV us .
  • Expression (2) is a mathematical formula representing the integrated part load value defined by JRAIA.
  • IPLV 0.01 ⁇ A + 0.47 ⁇ B + 0.37 ⁇ C + 0.15 ⁇ D
  • A is a COP at 100% load
  • B is a COP at 75% load
  • C is a COP at 50% load
  • D is a COP at 25% load.
  • the weight varies by operating load in a manner similar to the integrated part load value IPLV US defined by ARI.
  • some of the same operating loads as those in Expression (1) are assigned weights different from those in Expression (1).
  • 75% load accounts for 47% of annual operating time and is assigned the greatest weight.
  • a typical refrigeration cycle apparatus is operated at a rated condition in a very short time of a year, and is in a part-load operation in 90% or more of annual operating time. Most part-load operations are at loads of from 75% to 50% of full load. A part-load operation differs from a full-load operation in refrigerant circulation flow rate and operating compression ratio.
  • the COP also changes.
  • the above-described integrated part load value obtained in consideration of such an actual operating situation has attracted attention.
  • the integrated part load value is an index in which importance is placed on COPs at part load conditions.
  • Embodiment 1 for the economizer superheat degree ⁇ Tesh, which is the monitored target in economizer flow rate control, a target value associated with the greatest integrated part load value calculated using the mathematical formula expressed by Expression (2) can be obtained in advance.
  • 75% load of the four operating loads accounts for 47% of the annual operating time and is assigned the greatest weight. Attention can be paid to an operating load assigned the greatest weight.
  • An operating condition of interest is not limited to the operating load assigned the greatest weight. Attention may be paid to two or more operating loads selected in order from greatest weight to smallest weight. Operating conditions of interest may be all of the four operating loads included in Expression (2). The number of operating conditions of interest may be any number.
  • the calculating unit 34 may calculate, at each of the operating conditions, a compression ratio of the compressor 2 that is obtained when a value associated with a maximum COP is set, and obtain a target value of a monitored target associated with each compression ratio in advance, for example, in a break-in period of the refrigeration cycle apparatus 1.
  • the calculating unit 34 stores information representing the relationship between the compression ratios and the target values of the monitored target in the memory 31.
  • the calculating unit 34 may obtain, with respect to four operating conditions corresponding to the four operating loads included in the mathematical formula of Expression (2), compression ratios of the compressor 2 and target values of the monitored target associated with the respective compression ratios. In this case, the calculating unit 34 can estimate compression ratios at operating conditions other than the four operating conditions and target values associated with these compression ratios on the basis of the relationship between the compression ratios at the four operating conditions and the target values.
  • Fig. 3 is an explanatory graph illustrating an example of how to determine a target value of a monitored target on the basis of an operating state of the refrigerant circuit in economizer flow rate control in Embodiment 1 of the present disclosure.
  • Fig. 3 illustrates a case where a compression ratio, which is one of operating states of the refrigerant circuit 12, is used as a reference for target value determination.
  • the horizontal axis represents the compression ratio
  • the vertical axis represents the target value of the monitored target.
  • the vertical axis shown in Fig. 3 represents the target value of the economizer superheat degree ⁇ Tesh.
  • Fig. 3 illustrates points representing target values of the economizer superheat degree ⁇ Tesh associated with the compression ratios at four conditions: a condition Cond1 in which a maximum COP at 100% load is achieved; a condition Cond2 in which a maximum COP at 75% load is achieved; a condition Cond3 in which a maximum COP at 50% load is achieved; and a condition Cond4 in which a maximum COP at 25% load is achieved.
  • An approximate curve connecting the four points is represented by a dashed line. From the approximate curve, the calculating unit 34 can estimate target values associated with compression ratios that are not relevant to the four points. The calculating unit 34 can draw an approximate curve, as illustrated in Fig. 3 , on the basis of data representing target values of a monitored target associated with at least two conditions.
  • the calculating unit 34 may determine target values associated with operating conditions other than the four operating conditions corresponding to the four operating loads included in the mathematical formula of Expression (2) as follows.
  • the calculating unit 34 divides the range of compression ratios into four subranges on the basis of the relationship between the compression ratios obtained at the four operating conditions and the target values such that one of the four compression ratios corresponding to the above-described four operating conditions is included in each subrange. Then, the calculating unit 34 sets values of the four compression ratios corresponding to the above-described four operating conditions to respective target values of the compression ratios in the subranges.
  • the calculating unit 34 identifies a subrange including the calculated compression ratio out of subranges into which the range of compression ratios is divided, and determines a target value set in the identified subrange as a target value of a compression ratio.
  • target values associated with the four operating conditions may be any number.
  • the operating state of the refrigerant circuit 12 used as the basis to determine a target value may be a parameter other than the compression ratio.
  • the operating state of the refrigerant circuit 12 may be a pressure difference Pd (condensing pressure - evaporating pressure) between a high pressure and a low pressure in the refrigerant circuit 12 instead of the compression ratio.
  • the calculating unit 34 determines a target value of a monitored target on the basis of the pressure difference Pd.
  • the memory 31 may store target determination information used to identify a target value associated with an optimum integrated part load value IPLV for each of the range of condensing pressures and the range of evaporating pressures, and the calculating unit 34 may determine a target value on the basis of a detected condensing pressure and a detected evaporating pressure with reference to the target determination information. Additionally, the rotational frequency may be used to determine a target value.
  • Fig. 4 is a flowchart illustrating an operation procedure of the refrigeration cycle apparatus shown in Fig. 1 .
  • the controller 10 reads detection values of various sensors at predetermined intervals.
  • the calculating unit 34 calculates an economizer superheat degree ⁇ Tesh from a refrigerant temperature Te detected by the temperature sensor 13 and a saturated gas temperature Tesa corresponding to an intermediate pressure detected by the intermediate pressure sensor 8c.
  • the calculating unit 34 calculates a compression ratio on the basis of an evaporating pressure detected by the evaporating pressure sensor 8a and a condensing pressure detected by the condensing pressure sensor 8b.
  • the calculating unit 34 determines a target value Tset1 of the economizer superheat degree ⁇ Tesh on the basis of the calculated compression ratio (step S101). For example, the calculating unit 34 determines the target value Tset1 with reference to the graph shown in Fig. 3 .
  • the graph shown in Fig. 3 is stored in the memory 31.
  • the flow rate control unit 35 compares the calculated economizer superheat degree ⁇ Tesh with the target value Tset1 (step S102). When the economizer superheat degree ⁇ Tesh is less than the target value Tset1 as a result of comparison in step S102, the flow rate control unit 35 reduces the opening degree of the economizer expansion valve 7 (step S103). A reduction in the opening degree of the economizer expansion valve 7 leads to a reduction in intermediate pressure and a reduction in flow rate of the refrigerant flowing through the economizer circuit 11. As a result, a temperature of gas refrigerant to be injected rises, so that the economizer superheat degree ⁇ Tesh rises and approaches the target value Tset1.
  • the flow rate control unit 35 increases the opening degree of the economizer expansion valve 7 to reduce the economizer superheat degree ⁇ Tesh (step S104).
  • An increase in the opening degree of the economizer expansion valve 7 leads to an increase in intermediate pressure and an increase in flow rate of the refrigerant flowing through the economizer circuit 11. As a result, a temperature of gas refrigerant to be injected decreases, so that the economizer superheat degree ⁇ Tesh decreases and approaches the target value Tset1.
  • the flow rate control unit 35 keeps the opening degree of the economizer expansion valve 7 (step S105). As described above, the amount and temperature of the refrigerant to be injected into the compressor 2 are automatically adjusted to optimum values, at which a higher COP is achieved, in response to an operating load.
  • Fig. 5 is a refrigerant circuit diagram illustrating another exemplary configuration of the refrigeration cycle apparatus according to Embodiment 1 of the present disclosure.
  • Fig. 5 illustrates a refrigeration cycle apparatus 1a in which the economizer circuit 11 branches off from the refrigerant circuit between the intercooler 4 and the condenser 3 and connects to the compressor 2 via the economizer expansion valve 7 and the low pressure section 4b of the intercooler 4.
  • the economizer expansion valve 7 is disposed between the intercooler 4 and a branch point 15a located between the intercooler 4 and the condenser 3.
  • the refrigeration cycle apparatus 1 calculates the economizer superheat degree ⁇ Tesh as a monitored target.
  • the refrigeration cycle apparatus 1 determines a target value of the economizer superheat degree ⁇ Tesh on the basis of an operating state of the refrigerant circuit 12 and adjusts the opening degree of the economizer expansion valve 7 such that the economizer superheat degree ⁇ Tesh matches the target value.
  • the target value of the economizer superheat degree which is the monitored target, is set such that a higher COP is achieved at an actual operating load.
  • the opening degree of the economizer expansion valve is thus adjusted more appropriately than in a case where the target value is set to be constant. Annual efficiency is therefore improved.
  • the calculating unit 34 sets the target value at which a maximum COP is achieved at an operating load corresponding to, for example, a frequency or a compression ratio.
  • the refrigeration cycle apparatus 1 can improve the integrated part load value by exercising economizer flow rate control in response to an actual operating load such that a higher COP is achieved.
  • the calculating unit 34 may estimate a target value associated with a compression ratio on the basis of the different operating loads, included in the mathematical formula used to calculate the integrated part load value, to determine the target value. In this case, the calculating unit 34 can also determine optimum estimated target values of a monitored target associated with operating conditions other than the different operating loads included in the mathematical formula.
  • the calculating unit 34 may divide the range of compression ratios into subranges on the basis of compression ratios at the different operating loads included in the mathematical formula used to calculate the integrated part load value and determine a target value for each subrange.
  • the calculating unit 34 may use an operating load assigned the greatest weight or may use two or more operating loads selected from the different operating loads in order from greatest weight to smallest weight. In this case, as the number of operating loads used as the basis to determine target values of compression ratios is small, the calculating unit 34 can determine target values of a monitored target more quickly.
  • Embodiment 1 the economizer superheat degree is used for economizer flow rate control.
  • Embodiment 2 illustrates a case where a temperature of the refrigerant at a high-pressure side refrigerant outlet of the intercooler is used for economizer flow rate control.
  • the same components as those of the refrigeration cycle apparatus according to Embodiment 1 are designated by the same reference signs and a detailed description of these components is omitted.
  • part of the refrigerant flowing through the refrigerant circuit 12 is diverted to the economizer circuit 11 and flows through the low pressure section 4b of the intercooler 4.
  • the refrigerant flowing through the low pressure section 4b of the intercooler 4 cools the refrigerant flowing through the high pressure section 4a of the intercooler 4.
  • the refrigerant flowing through the economizer circuit 11 reduces the temperature of the refrigerant flowing through the high pressure section 4a of the intercooler 4.
  • the temperature and pressure of the refrigerant flowing through the economizer circuit 11 are detected and used to adjust the opening degree of the economizer expansion valve 7.
  • Embodiment 2 a change in temperature of the refrigerant at the high-pressure side refrigerant outlet of the intercooler 4 is detected and used to adjust the opening degree of the economizer expansion valve 7.
  • FIG. 6 is a refrigerant circuit diagram illustrating an example of the refrigeration cycle apparatus according to Embodiment 2 of the present disclosure.
  • a refrigeration cycle apparatus 1b according to Embodiment 2 includes an intercooler high-pressure side outlet temperature sensor 14 disposed at a high-pressure side refrigerant outlet of the intercooler 4.
  • the refrigeration cycle apparatus 1b shown in Fig. 6 includes no temperature sensor 13, which is illustrated in Fig. 1 .
  • the intercooler high-pressure side outlet temperature sensor 14 is disposed between the branch point 15 and the main expansion valve 5.
  • the intercooler high-pressure side outlet temperature sensor 14 detects the temperature of liquid refrigerant flowing through the refrigerant circuit 12 and flowing out from the intercooler 4.
  • the calculating unit 34 calculates a main refrigerant liquid approach temperature ⁇ Tsca, which is the difference between a refrigerant temperature Tm detected by the intercooler high-pressure side outlet temperature sensor 14 and a saturated gas temperature Tesa corresponding to an intermediate pressure.
  • the main refrigerant liquid approach temperature ⁇ Tsca is a monitored target used in economizer flow rate control.
  • Fig. 7 is a schematic diagram explaining the main refrigerant liquid approach temperature, which is a monitored target in economizer flow rate control in Embodiment 2 of the present disclosure.
  • Fig. 7 is a p-h diagram in which the vertical axis represents the pressure and the horizontal axis represents the specific enthalpy.
  • Fig. 7 schematically illustrates the main refrigerant liquid approach temperature ⁇ Tsca.
  • Fig. 8 is a flowchart illustrating an operation procedure of the refrigeration cycle apparatus shown in Fig. 6 .
  • the memory 31 stores a graph used to determine a target value of the main refrigerant liquid approach temperature ⁇ Tsca, which is the monitored target.
  • the graph is, for example, the graph shown in Fig. 3 .
  • the controller 10 reads detection values of the various sensors at predetermined intervals.
  • the calculating unit 34 calculates a main refrigerant liquid approach temperature ⁇ Tsca from a refrigerant temperature Tm detected by the intercooler high-pressure side outlet temperature sensor 14 and a saturated gas temperature Tesa corresponding to an intermediate pressure detected by the intermediate pressure sensor 8c.
  • the calculating unit 34 calculates a compression ratio by using detection values of the evaporating pressure sensor 8a and the condensing pressure sensor 8b.
  • the calculating unit 34 determines, on the basis of the calculated compression ratio, a target value Tset2 of the main refrigerant liquid approach temperature ⁇ Tsca (step S201).
  • the calculating unit 34 determines the target value Tset2 with reference to the graph shown in Fig. 3 .
  • the flow rate control unit 35 compares the calculated main refrigerant liquid approach temperature ⁇ Tsca with the target value Tset2 (step S202). When the main refrigerant liquid approach temperature ⁇ Tsca is less than the target value Tset2 as a result of comparison in step S202, the flow rate control unit 35 reduces the opening degree of the economizer expansion valve 7 (step S203). A reduction in the opening degree of the economizer expansion valve 7 leads to a reduction in intermediate pressure and a reduction in flow rate of the refrigerant flowing through the economizer circuit 11. As a result, an amount of heat exchanged between the high-pressure side refrigerant and the low-pressure side refrigerant in the intercooler decreases, so that the refrigerant temperature Tm rises. Thus, the main refrigerant liquid approach temperature ⁇ Tsca increases and approaches the target value Tset2.
  • the flow rate control unit 35 increases the opening degree of the economizer expansion valve 7 to reduce the main refrigerant liquid approach temperature ⁇ Tsca (step S204).
  • An increase in the opening degree of the economizer expansion valve 7 leads to an increase in intermediate pressure and an increase in flow rate of the refrigerant flowing through the economizer circuit 11.
  • an amount of heat exchanged between the high-pressure side refrigerant and the low-pressure side refrigerant in the intercooler increases, so that the refrigerant temperature Tm decreases.
  • the main refrigerant liquid approach temperature ⁇ Tsca decreases and approaches the target value Tset2.
  • the flow rate control unit 35 keeps the opening degree of the economizer expansion valve 7 (step S205). As described above, the amount and temperature of the refrigerant to be injected into the compressor 2 are automatically adjusted to optimum values, at which a higher COP is achieved, in response to an operating load.
  • the target value of the main refrigerant liquid approach temperature ⁇ Tsca is not limited to those in the graph shown in Fig. 3 .
  • the target value of the main refrigerant liquid approach temperature ⁇ Tsca may be obtained from the relationship between the COPs at the four operating loads included in the mathematical formula of Expression (2) and the compression ratios of the compressor 2.
  • a COP used as the basis to determine the target value may be a COP associated with an operating load assigned the greatest weight of the four operating loads included in the mathematical formula of Expression (2) or may be estimated from two or more COPs selected in order from greatest weight to smallest weight.
  • the main refrigerant liquid approach temperature ⁇ Tsca is calculated, a target value of the main refrigerant liquid approach temperature ⁇ Tsca is determined on the basis of a compression ratio, and the opening degree of the economizer expansion valve 7 is adjusted such that the main refrigerant liquid approach temperature ⁇ Tsca matches the target value.
  • the target value of the main refrigerant liquid approach temperature is set such that a higher COP is achieved at an actual operating load.
  • the opening degree of the economizer expansion valve is thus adjusted more appropriately than in the case where the target value is set to be constant. Annual efficiency is therefore improved.
  • Embodiment 2 has the same connection configuration as in Fig. 1
  • the economizer circuit 11 may have the same connection configuration as in Fig. 5 .
  • the forms of the components described in Embodiments 1 and 2 are intended to be illustrative only and are not intended to be limited to those described in these embodiments and illustrated in the drawings. Additionally, pressure levels are not determined in relation to a particular absolute value but are relatively determined depending on, for example, a state and an operation of the refrigeration cycle apparatus.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Air Conditioning Control Device (AREA)
EP18936213.0A 2018-10-02 2018-10-02 Appareil à cycle frigorifique Pending EP3862649A4 (fr)

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PCT/JP2018/036849 WO2020070793A1 (fr) 2018-10-02 2018-10-02 Appareil à cycle frigorifique

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EP3862649A1 true EP3862649A1 (fr) 2021-08-11
EP3862649A4 EP3862649A4 (fr) 2022-01-12

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CN113465105B (zh) * 2021-06-21 2022-12-27 青岛海尔空调电子有限公司 用于空调器的补气增焓控制方法
CN115200177A (zh) * 2022-05-27 2022-10-18 宁波奥克斯电气股份有限公司 补气增焓控制方法、装置及空调器

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JPH0593548A (ja) * 1991-04-08 1993-04-16 Mitsubishi Heavy Ind Ltd 冷凍装置
US6718781B2 (en) * 2001-07-11 2004-04-13 Thermo King Corporation Refrigeration unit apparatus and method
JP2007205612A (ja) * 2006-01-31 2007-08-16 Mitsubishi Electric Corp 冷凍サイクル装置
WO2011064927A1 (fr) * 2009-11-25 2011-06-03 ダイキン工業株式会社 Dispositif de réfrigération pour contenant
JP5463192B2 (ja) 2010-04-20 2014-04-09 三菱重工業株式会社 エコノマイザ回路付き冷凍装置
JP5911567B2 (ja) * 2012-04-27 2016-04-27 三菱電機株式会社 空気調和装置
JP6177450B2 (ja) * 2014-09-24 2017-08-09 三菱電機株式会社 スクリュー圧縮機および冷凍サイクル装置
EP3124897B1 (fr) * 2015-07-27 2018-02-21 Honeywell spol s.r.o. Procédés et appareil de commande de circuit de compression de vapeur
CN105973626B (zh) * 2016-05-25 2018-11-30 深圳达实智能股份有限公司 中央空调系统主机运行能效评估及预测方法以及装置

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* Cited by examiner, † Cited by third party
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CN114353383A (zh) * 2021-12-10 2022-04-15 青岛海尔空调电子有限公司 空气源热泵机组控制方法及空气源热泵机组
CN114353383B (zh) * 2021-12-10 2024-04-19 青岛海尔空调电子有限公司 空气源热泵机组控制方法及空气源热泵机组

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JP6987269B2 (ja) 2021-12-22
EP3862649A4 (fr) 2022-01-12

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