Apparatus and method for detecting faults and providing diagnostics in vapor compression cycle equipment

• US 6,658,373 B2
• Filed: 08/24/2001
• Issued: 12/02/2003
• Est. Priority Date: 05/11/2001
• Status: Expired due to Term

• Current Assignee: Mcloud Technologies (USA) Inc.
• Original Assignee: Field Diagnostic Services, Inc. (mCloud Technologies Corp.)
• Inventors: Rossi, Dale, Stockman, Timothy P., Rossi, Todd M., Douglas, Jonathan D.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Barbee, Manuel L.
• Application Number:
  US09/939,012
• Publication Number:
  US 20030055603A1
• Time in Patent Office: 830 Days
• Field of Search: 702/45, 702/47, 702/50, 702/55, 702/98-100, 702/113, 702/114, 702/130, 702/136, 702/138, 702/140, 702/182-185, 621/25, 621/27, 621/29, 340/585
• US Class Current: 702/185
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/38 Failure diagnosis
• CPC Class Codes: F24F 11/54 using one central controller connected to several sub-controllers
• CPC Class Codes: F25B 2500/19 Calculation of parameters
• CPC Class Codes: F25B 2600/19 Refrigerant outlet condenser temperature
• CPC Class Codes: F25B 2600/21 Refrigerant outlet evaporator temperature
• CPC Class Codes: F25B 2700/02 Humidity
• CPC Class Codes: F25B 2700/1931 Discharge pressures
• CPC Class Codes: F25B 2700/1933 Suction pressures
• CPC Class Codes: F25B 2700/195 of the condenser
• CPC Class Codes: F25B 2700/2106 of fresh outdoor air
• CPC Class Codes: F25B 2700/21151 at the suction side of the compressor
• CPC Class Codes: F25B 2700/21161 of the fluid heated by the condenser
• CPC Class Codes: F25B 2700/21163 of the refrigerant at the outlet of the condenser
• CPC Class Codes: F25B 2700/21172 at the inlet
• CPC Class Codes: F25B 49/005 of safety devices F25B49/02 and F25B49/04 take precedence
• CPC Class Codes: F25B 49/02 for compression type machines, plants or systems

Abstract

An apparatus and method for detecting faults and providing diagnostic information in a refrigeration system comprising a microprocessor, a means for inputting information to the microprocessor, a means for outputting information from the microprocessor, and five sensors.

Claims

1. A method of providing diagnostics of a refrigeration system, the method comprising:

a) measuring liquid line refrigerant pressure (LP), suction line refrigerant pressure (SP), suction line temperature (ST), liquid line temperature (LT), and outdoor atmospheric temperature (AMB) used to cool the condenser;

b) when the liquid pressure port is not available, measure the discharge pressure (DP), setting LP equal to DP (or accounting for the condenser pressure drop);

c) calculating the pressure difference (PD) between the liquid pressure (LP) and the suction pressure (SP);

d) calculating the condensing temperature (CT) as the saturated temperature at the liquid line pressure (LP);

e) calculating liquid line subcooling (SC) using the liquid line temperature (LT) and the condensing temperature (CT);

f) calculating condensing temperature over ambient (CTOA) using CT and AMB;

g) calculating evaporating temperature (ET) as the saturated temperature at the suction pressure (SP);

h) calculating suction line superheat (SH) using suction line temperature (ST) and pressure (SP);

i) determining the presence of a fault and, if so, a consequent diagnostics of the refrigeration system based on operating limits for at least one of the following parameters;

pressure difference (PD), evaporating temperature (ET), suction line superheat (SH), liquid line subcooling (SC), condenser temperature over ambient (CTOA).

2. The method of claim 1 further comprising:

a) measuring discharge refrigerant temperature (DT), return air temperature (RA), supply air temperature (SA), air off condenser temperature (AOC);

b) calculating condenser temperature difference (CTD) using AOC and AMB;

c) calculating evaporator temperature difference (ETD) using RA and SA.

d) determining the presence of a fault and, if so, a consequent diagnostics of the refrigeration system based on operating limits for at least one of the following parameters;

condenser temperature difference (CTD) and evaporator temperature difference (ETD).