Air conditioning apparatus

• US 7,987,679 B2
• Filed: 02/24/2005
• Issued: 08/02/2011
• Est. Priority Date: 02/24/2005
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Tomita, Masahumi, Shida, Yasunori, Yamashita, Kouji, Tanaka, Kousuke
• Primary Examiner(s): Jules; Frantz F
• Assistant Examiner(s): AZIM, ABDUR RAHIM
• Application Number:
  US11/547,609
• Publication Number:
  US 20070204635A1
• Time in Patent Office: 2,350 Days
• Field of Search: 621/27, 621/29, 622/08, 622/09, 622/25, 621/60, 621/25, 621/26, 62/6
• US Class Current: 62/129
• CPC Class Codes: F25B 13/00 Compression machines, plants or systems, with reversible cycle defrosting cycles F25B47/02
• CPC Class Codes: F25B 2309/061 with cycle highest pressure above the supercritical pressure
• CPC Class Codes: F25B 2313/02741 using one four-way valve
• CPC Class Codes: F25B 2313/0293 related to the indoor fan, e.g. controlling speed
• CPC Class Codes: F25B 2313/0294 related to the outdoor fan, e.g. controlling speed
• CPC Class Codes: F25B 2313/0314 Temperature sensors near the indoor heat exchanger
• CPC Class Codes: F25B 2313/0315 Temperature sensors near the outdoor heat exchanger
• CPC Class Codes: F25B 2500/19 Calculation of parameters
• CPC Class Codes: F25B 2500/222 Detecting refrigerant leaks
• CPC Class Codes: F25B 2600/2513 Expansion valves
• CPC Class Codes: F25B 49/005 of safety devices F25B49/02 and F25B49/04 take precedence
• CPC Class Codes: F25B 9/008 the refrigerant being carbon dioxide

Abstract

By studying or storing refrigerating cycle characteristics of an air conditioning apparatus at the normal time and comparing them with refrigerating cycle characteristics acquired from the air conditioning apparatus at the time of operation, it becomes possible to exactly and accurately diagnose normality or abnormality of the air conditioning apparatus under any installation conditions and environmental conditions, which eliminates operations of inputting a difference between apparatus model names, a piping length, a height difference, etc at the time of apparatus installation. Accordingly, it aims at shortening the time of judging normality or abnormality, and improving the operability. It is characterized by calculating and comparing a measured value (a value of liquid phase temperature efficiency ε_L (SC/dT_c) calculated from temperature information) concerning an amount of a liquid phase part of the refrigerant in the high-pressure-side heat exchanger with a theoretical value (a value of liquid phase temperature efficiency ε_L (1−EXP(−NTU_R)) calculated from the transfer unit number NTU_R at refrigerant side).

Claims

1. An air conditioning apparatus comprising:

a refrigerating cycle to connect a compressor, a high-pressure-side heat exchanger, a throttle device and a low-pressure-side heat exchanger by piping, to circulate a refrigerant of high temperature and high pressure in the high-pressure-side heat exchanger, and to circulate a refrigerant of low temperature and low pressure in the low-pressure-side heat exchanger;

a temperature detection part of high-pressure refrigerant to detect a temperature of the refrigerant in the high-pressure-side heat exchanger;

a temperature detection part of high-pressure-side heat exchanger entrance-side refrigerant to detect a temperature of the refrigerant at an entrance side of the high-pressure-side heat exchanger;

a temperature detection part of high-pressure-side heat exchanger exit-side refrigerant to detect a temperature of the refrigerant at an exit side of the high-pressure-side heat exchanger;

a fluid temperature detection part to detect a temperature at a location of the fluid circulating outside of the high-pressure-side heat exchanger;

a calculation comparison part to calculate a first value obtained by dividing a supercooling degree SC which is obtained by subtracting the temperature detected by the temperature detection part of high-pressure-side heat exchanger exit-side refrigerant from the temperature detected by the temperature detection part of high-pressure refrigerant, by dT_c which is a value obtained by subtracting the temperature detected by the fluid temperature detection part from the temperature detected by the temperature detection part of high-pressure refrigerant, and 1−

EXP(−

NTU_R) as a second value based on NTU_R which is obtained by calculating (Δ

H_CON×

A_L)/(dT_c×

C_pr×

A) (where Δ

H_CON is an enthalpy difference between an enthalpy at the entrance of the high-pressure-side heat exchanger which is calculated from the temperature detected by the temperature detection part of high-pressure-side heat exchanger entrance-side refrigerant and the temperature detected by the temperature detection part of high-pressure refrigerant and an enthalpy at the exit of the high-pressure-side heat exchanger which is calculated from the temperature detected by the temperature detection part of high-pressure-side heat exchanger exit-side refrigerant and the temperature detected by the temperature detection part of high-pressure refrigerant, A_L is a heating surface area of liquid phase of the high-temperature-side heat exchanger, A is a heating surface area of the high-temperature-side heat exchanger, and C_pr is a specific heat at constant pressure of the refrigerant), and compare the first value calculated and the second value calculated; and

a judgment part to judge a refrigerant leak based on a comparison result of the calculation comparison part.

2. The air conditioning apparatus of claim 1, further comprising

a control part to execute an initial learning operation which is aimed at obtaining a value serving to calculate A_L and A in (Δ

H_CON ×

A_L)/(dT_c×

C_pr×

A) and determined by specifications of the air conditioning apparatus and which is operated while changing setting of the refrigerating cycle;

wherein the calculation comparison part calculates A_L and A based on the value obtained in the initial learning operation executed by the control part, and calculates (Δ

H_CON ×

A_L)/(dT_c×

C_pr×

A) based on A_L calculated and A calculated.

3. The air conditioning apparatus of claim 1, further comprising:

a fluid sending part to make a fluid circulate outside of the high-pressure-side heat exchanger in order to perform a heat exchange between the refrigerant in the high-pressure-side heat exchanger and the fluid; and

a control part to control operation of the fluid sending part to make a temperature difference between the temperature detected by the temperature detection part of high-pressure refrigerant and the temperature detected by the fluid temperature detection part be close to a predetermined value;

wherein the calculation comparison part calculates the first value and the second value after the control part controls, and compares the first value and second value calculated.

4. The air conditioning apparatus of claim 1, further comprising:

a control part to control a frequency of the compressor to make a temperature difference between the temperature detected by the temperature detection part of high-pressure refrigerant and the temperature detected by the fluid temperature detection part be close to a predetermined value;

wherein the calculation comparison part calculates the first value and the second value after the control part controls, and compares the first value and second value calculated.

5. The air conditioning apparatus of claim 1, further comprising:

a temperature detection part of low-pressure refrigerant to detect a temperature of the refrigerant in the low-pressure-side heat exchanger; and

a control part which controls a degree of opening of the throttle device to make the temperature detected by the temperature detection part of low-pressure refrigerant be close to a predetermined value;

wherein the calculation comparison part calculates the first value and the second value after the control part controls, and compares the first value and second value calculated.

6. The air conditioning apparatus of claim 1, further comprising:

a temperature detection part of low-pressure refrigerant to detect a temperature of the refrigerant in the low-pressure-side heat exchanger;

a temperature detection part of low-pressure-side heat exchanger exit-side refrigerant to detect a temperature of the refrigerant at an exit side of the low-pressure-side heat exchanger; and

a control part which controls a degree of opening of the throttle device such that a degree of superheat calculated by subtracting the temperature detected by the temperature detection part of low-pressure-side heat exchanger exit-side refrigerant from the temperature detected by the temperature detection part of low-pressure refrigerant becomes not less than a predetermined value;

wherein the calculation comparison part calculates the first value and the second value after the control part controls, and compares the first value and second value calculated.

7. The air conditioning apparatus of claim 1,

wherein the throttle device includes an upstream side throttle device, a receiver, and a downstream side throttle device,

the air conditioning apparatus further comprising:

a control part which performs a special operation mode that the control part moves a surplus refrigerant in the receiver into the high-pressure-side heat exchanger by making the refrigerant at an exit of the receiver be a two-phase state by way of making an opening area of the upstream side throttle device be smaller than an opening area of the downstream side throttle device; and

wherein the calculation comparison part calculates the first value and the second value after the control part performs the special operation mode, and compares the first value and second value calculated.

8. The air conditioning apparatus of claim 1, further comprising:

an accumulator provided between the low-pressure-side heat exchanger and the compressor; and

a control part which performs a special operation mode that the control part moves a surplus refrigerant in the accumulator into the high-pressure-side heat exchanger by making the refrigerant flowing into the accumulator be a gas refrigerant by way of controlling the throttle device;

wherein the calculation comparison part calculates the first value and the second value after the control part performs the special operation mode, and compares the first value and second value calculated.

9. The air conditioning apparatus of claim 7, further comprising:

a timer;

wherein the control part performs the special operation mode every specific time period counted by the timer.

10. The air conditioning apparatus of claim 8, further comprising:

a timer;

wherein the control part performs the special operation mode every specific time period counted by the timer.

11. The air conditioning apparatus of claim 7,

wherein the control part performs the special operation mode by an operation signal from outside by wired or wireless.

12. The air conditioning apparatus of claim 8,

wherein the control part performs the special operation mode by an operation signal from outside by wired or wireless.

13. An air conditioning apparatus comprising:

a refrigerating cycle to connect a compressor, a high-pressure-side heat exchanger, a throttle device and a low-pressure-side heat exchanger by piping, to circulate a refrigerant of high temperature and supercritical pressure in the high-pressure-side heat exchanger, and to circulate a refrigerant of low temperature and low pressure in the low-pressure-side heat exchanger;

a pressure detection part of high-pressure refrigerant to detect a pressure of the refrigerant in the high-pressure-side heat exchanger;

a temperature detection part of high-pressure-side heat exchanger entrance-side refrigerant to detect a temperature of the refrigerant at an entrance side of the high-pressure-side heat exchanger;

a temperature detection part of high-pressure-side heat exchanger exit-side refrigerant to detect a temperature of the refrigerant at an exit side of the high-pressure-side heat exchanger;

a fluid temperature detection part to detect a temperature at a location of the fluid circulating outside of the high-pressure-side heat exchanger;

a calculation comparison part to calculate a first value obtained by dividing SC which is a value obtained by subtracting the temperature detected by the temperature detection part of high-pressure-side heat exchanger exit-side refrigerant from an imaginary saturation temperature which is a temperature of the refrigerant in a case wherein an enthalpy of a refrigerant at the pressure detected by the pressure detection part of high-pressure refrigerant is an enthalpy at a critical point of the refrigerant, by dT_c which is a value obtained by subtracting the temperature detected by the fluid temperature detection part from the imaginary saturation temperature, and 1−

EXP(−

NTU_R) as a second value based on NTU_R which is obtained by calculating (Δ

H_CON×

A_L)/(dT_c×

C_pr×

A) (where Δ

H_CON is an enthalpy difference between an enthalpy at the entrance of the high-pressure-side heat exchanger which is calculated from the temperature detected by the temperature detection part of high-pressure-side heat exchanger entrance-side refrigerant and the pressure detected by the pressure detection part of high-pressure refrigerant and an enthalpy at the exit of the high-pressure-side heat exchanger which is calculated from the temperature detected by the temperature detection part of high-pressure-side heat exchanger exit-side refrigerant and the pressure detected by the pressure detection part of high-pressure refrigerant, A_L is a heating surface area of liquid phase of the high-temperature-side heat exchanger, A is a heating surface area of the high-temperature-side heat exchanger, and C_pr is a specific heat at constant pressure of the refrigerant), and compare the first value calculated and the second value calculated; and

a judgment part to judge a refrigerant leak based on a comparison result of the calculation comparison part.

14. The air conditioning apparatus of claim 13, wherein a refrigerant of CO₂ is used.