Source: http://www.google.com/patents/US8024938?dq=7350717
Timestamp: 2016-05-29 17:37:13
Document Index: 500629769

Matched Legal Cases: ['Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'art. 4', 'art. 4', 'art.\n5']

Patent US8024938 - Method for determining evaporator airflow verification - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA method of providing a field test protocol for determining evaporator airflow verification for existing vapor compression cycle equipment....http://www.google.com/patents/US8024938?utm_source=gb-gplus-sharePatent US8024938 - Method for determining evaporator airflow verificationAdvanced Patent SearchPublication numberUS8024938 B2Publication typeGrantApplication numberUS 11/985,170Publication dateSep 27, 2011Filing dateNov 14, 2007Priority dateNov 14, 2006Fee statusPaidAlso published asUS20080196421Publication number11985170, 985170, US 8024938 B2, US 8024938B2, US-B2-8024938, US8024938 B2, US8024938B2InventorsTodd M. Rossi, Keith A. Temple, Changlin SunOriginal AssigneeField Diagnostic Services, Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (42), Non-Patent Citations (8), Referenced by (3), Classifications (6), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetMethod for determining evaporator airflow verification
US 8024938 B2Abstract
A method of providing a field test protocol for determining evaporator airflow verification for existing vapor compression cycle equipment.
1. A method of testing a refrigeration system comprising the steps of:
operating a compressor of the circuit to be tested under full load in cooling mode for the refrigeration circuit to be tested;
allowing the compressor for the circuit to be tested to reach at least a quasi-steady operating condition;
measuring the refrigeration cycle parameters;
where the refrigeration cycle parameters include at least the entering air dry-bulb temperature, suction line temperature, suction line pressure, and the return air wet-bulb temperature;
where at least one of the liquid line pressure or the discharge line pressure is measured;
using one measured parameter to determine a condenser saturation temperature;
calculating at least one performance parameter;
determining at least one corresponding target parameter and range from those parameters and ranges specified by said refrigeration system's manufacturer;
comparing at least one performance parameter to the corresponding target parameter and range;
determining whether the performance parameter falls outside the target parameter and range;
where if the performance parameter falls outside the target parameter and range then the refrigeration system is eligible for correction;
where the condenser saturation temperature is determined from the liquid line pressure;
where the performance parameter is condensing temperature over ambient;
where condensing temperature over ambient is calculated from the condenser saturation temperature and the entering air dry-bulb temperature;
where the condensing temperature over ambient is compared to the corresponding target parameter; and
where the condensing temperature over ambient must be at least one of less than about +30� F. or less than about 10� F. over the manufacturer's recommended target parameter for a valid verification test.
2. A method of testing a refrigeration system comprising the steps of:
determining at least one target parameter and range from those parameters and ranges specified by said refrigeration system's manufacturer;
where if the performance parameter falls outside the target parameter and range then the system is eligible for correction;
where the relation of condensing temperature over ambient to a corresponding target parameter determines a valid verification test.
3. The method of claim 1 where the evaporator saturation temperature is determined from suction line pressure.
calculating an actual superheat from the suction line temperature and the evaporator saturation temperature;
determining a target evaporator saturation temperature; and
calculating a difference of evaporator saturation temperature from evaporator saturation temperature and a target evaporator saturation temperature.
determining a target superheat; and
calculating a difference of superheat from the actual superheat and the target superheat.
6. The method of claim 5 further comprising the step of determining whether a TxV metering device or a non-TxV metering device is being tested.
7. The method of claim 6 where the airflow system is being verified.
8. The method of claim 7 further comprising the steps of evaluating the difference of evaporating saturation temperature and the difference of superheat.
9. The method of claim 6 where the refrigeration system is being verified.
measuring liquid line temperature;
calculating an actual subcooling by subtracting liquid line temperature from condensing temperature;
determining a target subcooling; and
calculating a difference of subcooling from the actual subcooling and the target subcooling.
11. The method of claim 10 further comprising the step of performing at least one of evaluating the difference of superheat limits or evaluating the difference of subcooling.
12. A method for determining airflow verification of a refrigeration unit, the method comprising the steps:
placing the refrigeration unit under full load;
measuring condenser entering air dry-bulb temperature (Toutdoor, db);
measuring return air wet-bulb temperature (Treturn, wb);
measuring suction line refrigerant temperature (Tsuction) at compressor suction;
measuring suction line refrigerant pressure (Pevaporator) at compressor suction;
measuring liquid line refrigerant pressure (Pcondenser) at the condenser outlet;
determining the condenser saturation temperature (Tcondenser) from the standard refrigerant saturated pressure/temperature chart, using the liquid line pressure (Pcondenser);
calculating Condensing temperature over ambient (Tcoa) as the condenser saturation temperature minus the Condenser entering air temperature
Tcoa=Tcondenser−Toutdoor;
checking to ensure the condensing temperature over ambient (Tcoa) is less than +30� F. for a valid airflow verification test;
determining the evaporating (saturation) temperature (Tevaporator) from a standard refrigerant saturated pressure/temperature chart, using the suction line pressure (Pevaporator);
calculating Actual Superheat as the suction line temperature minus the evaporator saturation temperature
Actual Superheat=Tsuction−Tevaporator;
for a Non-TxV metering device, determining the Target Superheat using FIGS. 1A and 1B—Table RD-2 or equivalent using the return air wet-bulb temperature (Treturn, wb) and condenser air dry-bulb temperature (Toutdoor, db), otherwise, for a TxV metering device, the Target Superheat is 20� F.;
using the return air wet-bulb temperature (Treturn, wb) and condenser air dry-bulb temperature (Toutdoor, db), determine the target evaporating temperature using (a) FIG. 3A—Table RD-4a, (b) FIG. 3B —Table RD-4b, (c) OEM provided equivalent for refrigeration system being tested, or (d) alternate method appropriate for refrigeration system being tested that considers variation with return air wet-bulb temperature (Treturn, wb) and condenser air dry-bulb temperature (Toutdoor, db);
calculating the difference (DTevap) and target evaporating temperature
DTevap=Actual Evaporating Temperature−Target Evaporating Temperature;
calculate the difference (DTsh) between actual superheat and target superheat
DTsh=Actual Superheat−Target Superheat.
13. A method for determining evaporator airflow verification of a refrigeration unit, the method comprising the steps:
a) place the refrigeration unit under full load;
b) measure condenser entering air dry-bulb temperature (Toutdoor, db);
c) measure return air wet-bulb temperature (Treturn, wb);
d) measure suction line refrigerant temperature (Tsuction) at compressor suction;
e) measure suction line refrigerant pressure (Pevaporator) at compressor suction;
f) measure liquid line refrigerant pressure (P condenser) at the condenser outlet;
g) determine the condenser saturation temperature (Tcondenser) from a standard refrigerant saturated pressure/temperature chart, using the liquid line pressure (Pcondenser);
h) calculate Condensing temperature over ambient (Tcoa) as the condenser saturation temperature minus the Condenser entering air temperature
i) check to ensure the condensing temperature over ambient (Tcoa) is less than +30� F. for a valid airflow verification test;
j) determine the evaporating (saturation) temperature (Tevaporator) from the standard refrigerant saturated pressure/temperature chart, using the suction line pressure (Pevaporator);
k) calculate Actual Superheat as the suction line temperature minus the evaporator saturation temperature
l) for a Non-TxV metering device, determine the Target Superheat using FIGS. 1A and 1B—Table RD-2 or equivalent using the return air wet-bulb temperature (Treturn, wb) and condenser air dry-bulb temperature (Toutdoor, db), otherwise, for a TxV metering device, the Target Superheat is 20� F. or the original equipment manufacturer (OEM) recommended value;
m) using the return air wet-bulb temperature (Treturn, wb) and condenser air dry-bulb temperature (Toutdoor, db), determine the target evaporating temperature using (a) FIG. 3A—Table RD-4a, (b) FIG. 3B—Table RD-4b, (c) OEM provided equivalent for refrigeration system being tested, or (d) alternate method appropriate for refrigeration system being tested that considers variation with return air wet-bulb temperature (Treturn, wb) and condenser air dry-bulb temperature (Toutdoor, db);
n) calculate the difference (DTevap) between actual evaporating temperature and target evaporating temperature
o) calculate the difference (DTsh) between actual superheat and target superheat
DTsh=Actual Superheat−Target Superheat;
p) compare DTevap to the recommended threshold; and
q) compare DTsh to the recommended threshold.
14. A method for determining airflow verification of a refrigeration unit, the method comprising the steps:
measuring discharge line refrigerant pressure (Pdischarge) at the compressor outlet;
calculating Pcondenser as Pdischarge minus 15 psi;
using the return air wet-bulb temperature (Treturn, wb) and condenser air dry-bulb temperature (Toutdoor, db), determine the target evaporating temperature using (a) FIG. 3A—Table RD-4a, (b) FIG. 3B—Table RD-4b, (c) OEM provided equivalent for refrigeration system being tested, or (d) alternate method appropriate for refrigeration system being tested that considers variation with return air wet-bulb temperature (Treturn, wb) and condenser air dry-bulb temperature (Toutdoor, db);
DTsh=Actual Superheat—Target Superheat.
15. A method for determining evaporator airflow verification of a refrigeration unit, the method comprising the steps:
f) measure discharge line refrigerant pressure (Pdischarge) at the compressor outlet;
g) calculate Pcondenser as Pdischarge minus 15 psi;
h) determine the condenser saturation temperature (Tcondenser) from a standard refrigerant saturated pressure/temperature chart, using the liquid line pressure (Pcondenser);
i) calculate Condensing temperature over ambient (Tcoa) as the condenser saturation temperature minus the Condenser entering air temperature
j) check to ensure the condensing temperature over ambient (Tcoa) is less than +30� F. for a valid airflow verification test;
k) determine the evaporating (saturation) temperature (Tevaporator) from the standard refrigerant saturated pressure/temperature chart, using the suction line pressure (Pevaporator);
l) calculate Actual Superheat as the suction line temperature minus the evaporator saturation temperature
m) for a Non-TxV metering device, determine the Target Superheat using FIGS. 1A and 1B—Table RD-2 or equivalent using the return air wet-bulb temperature (Treturn, wb) and condenser air dry-bulb temperature (Toutdoor, db), otherwise, for a TxV metering device, the Target Superheat is 20� F. or the original equipment manufacturer (OEM) recommended value;
n) using the return air wet-bulb temperature (Treturn, wb) and condenser air dry-bulb temperature (Toutdoor, db), determine the target evaporating temperature using (a) FIG. 3A—Table RD-4a, (b) FIG. 3B—Table RD-4b, (c) OEM provided equivalent for refrigeration system being tested, or (d) alternate method appropriate for refrigeration system being tested that considers variation with return air wet-bulb temperature (Treturn, wb) and condenser air dry-bulb temperature (Toutdoor, db);
o) calculate the difference (DTevap) between actual evaporating temperature and target evaporating temperature
p) calculate the difference (DTsh) between actual superheat and target superheat
q) compare DTevap to the recommended threshold; and
r) compare DTsh to the recommended threshold.
The present application claims the benefit under any applicable U.S. statute, including 35 U.S.C. �119(e), to U.S. Provisional Application No. 60/859,158 filed Nov. 14, 2006, titled METHOD FOR DETERMINING REFRIGERATION AND AIRFLOW VERIFICATION in the name of Todd M. Rossi, Keith A. Temple and Changlin Sun, and to U.S. Provisional Application No. 60/875,237 filed Dec. 14, 2006, titled METHOD FOR EVALUATING REFRIGERATION CYCLE PERFORMANCE in the name of Keith A. Temple, Todd M. Rossi and Changlin Sun.
U.S. Provisional Application No. 60/859,158, filed Nov. 14, 2006, is hereby incorporated by reference as if fully set forth herein.
U.S. Provisional Application No. 60/875,237, filed Dec. 14, 2006, is hereby incorporated by reference as if fully set forth herein.
The present invention relates generally to vapor compression cycle equipment (refrigeration and air conditioning equipment) and, more specifically, to a method for providing a field test protocol for refrigeration and airflow verification for existing commercial units.
In view of the rising costs of energy and the effects of global warming, it is the goal of certain government agencies and electric service providers to save energy and, in particular, electricity by improving the efficiency of equipment that utilizes electricity. Two active players in this endeavor are the California Energy Commission and the Southern California Edison Company. A program implemented in California and will likely be adopted by other states is the Refrigerant Charge and Airflow Verification Program (RCAVP).
Under the RCAVP, refrigeration systems, including Heating, Ventilation and Air Conditioning (HVAC) Systems in general, have their refrigerant charge and air flow verified and, if necessary, adjusted in order to improve efficiency and save energy. It was found that HVAC systems with TVX (thermostatic expansion valves) were just as likely as non-TVX systems to require adjustment to operate at peak or near-peak efficiency.
Based on studies, it was determined that HVAC technicians do not (or are not trained to) finely tune refrigeration systems upon installation, and that proper charge in refrigeration systems tend to degrade over time. More disturbing was the fact that HVAC technicians did not understand the relationship between refrigerant charge and operating efficiency.
The present invention describes a method of evaluating the efficiency of condensers and evaporators in vapor compression cycle equipment. The method discloses setting up the refrigeration system, the testing setup, and protocols for the evaluations of both condensers and evaporators. The protocol can be applied to packaged or split systems, air-cooled air conditioning or heat pump systems, constant volume or variable volume indoor fans, and constant speed or variable speed compressors, single or tandem in circuit, including un-loaders.
The present invention also describes a series of calculations to be used in the evaluation, and identifies the point at which corrections will be necessary.
The primary issues the present invention is intended to address, and some relevant background information, are set forth in the following two documents which are attached hereto and labeled Attachment 1 and Attachment 2, respectively.
SCE Program: Verified Charge and Airflow Services, Technical Specifications. CSG, 2006.
SDG&E Program: HVAC Training, Installation & Maintenance Program Technical Specifications. KEMA, Nov. 22, 2006.
Kindly incorporate by reference, as if fully set forth herein, the following four documents:
Title 24, 2005 Residential ACM Manual RD-2005, Appendix D—Procedures for Determining Refrigerant Charge for Split System space cooling systems without Thermostatic Expansion Valves.
Title 24, 2005 Residential ACM Manual RE-2005, Appendix E—Field Verification and Diagnostic Testing of Forced Air System Fan Flow and Air Handler Fan Watt Draw Carrier Corporation, 1986. Required Superheat Calculator GT24-01 020-434. Syracuse, N.Y.: Carrier Corporation.
Carrier Corporation, 1994. Charging Procedures for Residential Condensing Units 020-122 Syracuse, N.Y.: Carrier Corporation. Carrier Corporation, 1986. Required Superheat Calculator GT24-01 020-434. Syracuse, N.Y.: Carrier Corporation. BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is the Title 24 ACM RD Table for determining Target Superheat;
FIG. 1B is a continuation of the Table shown in FIG. 1A;
FIG. 2 is the Title 24 ACM RD Table for determining Target Temperature Split;
FIG. 3A is a chart showing Target Evaporating Temperature, TxV Metering Device in accordance with the present invention;
FIG. 3B is a chart showing Target Evaporating Temperature, Non-TxV Metering Device in accordance with the present invention; and
FIG. 4 is a chart outlining the basic steps of the method and process according to the present invention.
In describing a preferred embodiment of the present invention, specific terminology will be selected for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose.
The method/process for providing a field test protocol for evaporator airflow verification on existing vapor compression cycle equipment will be disclosed. The primary steps in the subject method are presented in FIG. 4.
Attachment 1 titled VERIFIED CHARGE AND AIRFLOW SERVICES—TECHNICAL SPECIFICATIONS, and Attachment 2 titled HVAC TRAINING, INSTALLATION & MAINTENANCE PROGRAM—TECHNICAL SPECIFICATIONS which form a part of this disclosure provide some of the background for the problems and issues the present method addresses.
2.1. Refrigeration Cycle Verification
2.1.1 Verify each circuit individually using the following Refrigeration Cycle Verification protocol. The procedure is outlined below; refer to the following sections for detailed requirements.
Outdoor air damper closed.
Circuit to be tested shall be operating fully loaded.
Measure refrigeration cycle parameters and driving conditions. Save Pre-Test data for each circuit prior to servicing unit.
Evaluate condensing temperature over ambient and check high limit. Resolve or stop if not satisfied.
Evaluate evaporating temperature and check high and low limits.
Resolve or stop if not satisfied.
Verify airflow using one of the approved protocols.
For TxV metering device check superheat limits (resolve or stop
if not satisfied), then evaluate charge using subcooling method
(pass/fail).
For non-TxV metering device evaluate charge using superheat
method (pass/fail).
Save Post-Test data for each circuit after servicing is complete.
2.2. Airflow Verification
2.2.1 Verify airflow using one of the available protocols.
2.2.2 Preferred approach is to verify airflow for each circuit using the Evaporator Performance Airflow Verification™ protocol, in conjunction with refrigeration cycle verification. The procedure is outlined below; refer to the following sections for detailed requirements.
2.2.2.1 Outdoor air damper closed. 2.2.2.2 Circuit to be tested shall be operating fully loaded. 2.2.2.3 Measure refrigeration cycle parameters and driving conditions. 2.2.2.4 Evaluate condensing temperature over ambient and check high limit. Resolve or stop if not satisfied. 2.2.2.5 Evaluate evaporating temperature and superheat. 2.2.2.6 Check evaporating temperature and superheat based on limits for particular metering device (pass/fail). 3. Test Setup
3.1 General Requirements for Refrigeration and Airflow Verification
3.1.1 This field protocol applies to the following existing commercial equipment:
3.1.1.1 Packaged or split system.
3.1.1.2 Air-cooled air conditioning or heat pump system.
Constant volume or variable volume indoor fan(s).
Constant speed or variable speed compressor(s), single or tandem
in circuit, including un-loaders.
3.1.2 This field protocol does not apply to the following equipment:
3.1.2.1 Systems with hot gas bypass control
3.1.3 Outdoor air damper should be closed and return air damper open (100% return air). When closing the outdoor air damper is not practical, testing may be completed with the outdoor air damper at minimum position with no more than approximately 20% outdoor air. The test configuration shall be documented. 3.1.4 The indoor fan shall be operating at the nominal cooling airflow rate. 3.1.5 For tests with one or more refrigeration circuits operating, all condenser fans shall be operating at full speed. 4. Refrigeration Cycle Verification
Refrigeration cycle verification must be completed for each independent refrigeration circuit
All compressors shall be operating fully loaded, for the
refrigeration circuit to be tested, for a minimum of fifteen (15) minutes in cooling mode to reach quasi-steady operating
conditions. There shall be constant control inputs to fans and compressors.
4.2. Refrigeration Cycle Verification—Each Circuit
Kindly incorporate by reference, as if fully set forth herein, the following documents:
Title 24 2005 Residential ACM Manual RD-2005, Appendix D—Procedures for Determining Refrigerant Charge for Split System space cooling systems without Thermostatic Expansion Valves
Title 24 2005 Residential ACM Manual RE-2005, Appendix E—Field Verification and Diagnostic Testing of Forced Air System Fan Flow and Air Handler Fan Watt Draw
Carrier Corporation, 1986. Required Superheat Calculator GT24-01 020-434. Syracuse, N.Y.: Carrier Corporation.
Carrier Corporation, 1994. Charging Procedures for Residential Condensing Units 020-122 Syracuse, N.Y.: Carrier Corporation.
4.2.1 Measurements: The following coincident measurements shall be made, in accordance with section 1.6.5 of Attachment 1, for the assessment of each refrigeration circuit:
Condenser entering air dry-bulb temperature (Toutdoor, db)
Return air wet-bulb temperature (Treturn, wb)
Suction line refrigerant temperature (Tsuction) at compressor suction
Suction line refrigerant pressure (Pevaporator) at compressor suction
Liquid line refrigerant pressure (Pcondenser) at the condenser
outlet (preferred) or discharge line refrigerant pressure
(Pdischarge) at the compressor outlet
Liquid line refrigerant temperature (Tliquid) at the condenser
4.2.2 Calculations and Criteria
4.2.2.1 If measuring discharge pressure instead of liquid line pressure, calculate Pcondenser as Pdischarge minus 15 psi (or OEM specification for condenser pressure drop if available). 4.2.2.2 Using the liquid line pressure (Pcondenser), determine the condenser saturation temperature (Tcondenser) from the standard refrigerant saturated pressure/temperature chart. 4.2.2.3 Calculate Condensing temperature over ambient (Tcoa) as the condenser saturation temperature minus the Condenser entering air temperature. Tcoa = Tcondenser − Toutdoor. 4.2.2.4 The condensing temperature over ambient (Tcoa) must be less than +30� F. for a valid verification test. Alternately, the condensing temperature over ambient (Tcoa) must be less than 10� F. over the manufacturer's recommended value. If the condition is not satisfied, the problem must be resolved before proceeding. Save Pre-Test data, for each circuit, prior to making any adjustments or servicing the unit. 4.2.2.5 Calculate Actual Subcooling as the condensing temperature minus liquid line temperature. Actual Subcooling = Tcondenser − Tliquid. 4.2.2.6 Using the suction line pressure (Pevaporator), determine the evaporating (saturation) temperature (Tevaporator) from the standard refrigerant saturated pressure/temperature chart. 4.2.2.7 Calculate Actual Superheat as the suction line temperature minus the evaporator saturation temperature. Actual Superheat = Tsuction − Tevaporator. 4.2.2.8 Using the return air wet-bulb temperature (Treturn, wb) and condenser entering air dry-bulb temperature (Toutdoor, db), determine the target evaporating temperature using (a) FIG. 3A - Table RD-4a, (b) FIG. 3B - Table RD-4b, (c) OEM provided equivalent for unit being tested, or (d) alternate method appropriate for unit being tested that considers variation with return air wet-bulb temperature (Treturn, wb) and condenser entering air dry-bulb temperature (Toutdoor, db). If the test conditions are outside the range of FIG. 3A - Table RD-4a and FIG. 3B - Table RD-4b, then the test cannot be used under these conditions. 4.2.2.9 Calculate the difference (DTevap) between actual evaporating temperature and target evaporating temperature. DTevap = Actual Evaporating Temperature − Target Evaporating Temperature. 4.2.2.10 The evaporating temperature difference (DTevap) must not be less than −10� F. (minus ten) or greater than +15� F. (plus fifteen) for a valid verification test. If DTevap limits are not satisfied, the problem must be resolved before proceeding. 4.2.2.11 For a Non-TxV metering device, determine the Target Superheat using FIG. 2 - Table RD-2 (reproduced in Appendix A) or equivalent using the return air wet-bulb temperature (Treturn, wb) and condenser entering air dry-bulb temperature (Toutdoor, db). If the test conditions are outside the range of the table, then the test cannot be used under these conditions. For a TxV metering device, the Target Superheat is 20� F. 4.2.2.12 Complete airflow verification before continuing with final charge verification. Airflow verification using the Evaporator Performance Airflow Verification ™ method may be completed in conjunction with the preceding elements of the refrigeration cycle verification. 4.2.2.13 Final charge verification for a Non-TxV metering device: Calculate the difference (DTsh) between actual superheat and target superheat. DTsh = Actual Superheat − Target Superheat. Final charge verification shall be completed using the superheat method described in sections 1.6.3 and 1.6.4 of Attachment 1. 4.2.2.14 Final charge verification for a TxV metering device: The Actual Superheat must be greater than 5� F. and less than 30� F. for a valid verification test. If the Actual Superheat limits are not satisfied, the problem must be resolved before proceeding. Calculate the difference (DTsc) between actual subcooling and target subcooling. DTsc = Actual Subcooling − Target Subcooling. Final charge verification shall be completed using the subcooling method described in sections 1.6.5 and 1.6.6 of Attachment 1. 4.2.2.15 Save Post-Test data, for each circuit, after servicing is complete. 5. Airflow Verification
5.1.1 System airflow shall be verified using one of the following methods.
5.2. Direct Airflow Measurement
5.2.1 The method shall comply with the requirements defined in section 1.6.8 of Attachment 1 (Verified Charge and Airflow Services, Technical Specification).
5.2.2 Direct airflow measurement shall be by one of the following methods: 5.2.2.1
Diagnostic fan flow using flow grid measurement
Diagnostic fan flow using flow capture hood
Airflow measurement using plenum pressure matching
5.3. Temperature Split Airflow Verification
The method shall comply with the requirements defined in section 1.6.7 of Attachment 1 (Verified Charge and Airflow Services,
Technical Specification).
System airflow must be verified for the unit with all circuits operating fully loaded for a minimum of 15 minutes in cooling mode. All compressors shall be operating fully loaded and there
shall be constant control inputs to fans and compressors.
5.4. Evaporator Performance Airflow Verification™
5.4.1 General:
5.4.1.1 The evaporator performance airflow verification method is designed to provide an efficient check to determine if airflow is
above the minimum required for a valid refrigerant charge test. The following steps describe the calculations to perform using measured data. If a system fails, then remedial actions must be
taken. This test should be conducted in conjunction with the refrigerant charge test. The test should be repeated after any system servicing, including airflow and charge adjustments.
5.4.1.2 System airflow must be verified using one of the following approaches:
Verify airflow for the unit with all circuits operating fully loaded
for a minimum of 15 minutes in cooling mode. All compressors shall be operating fully loaded and there shall be constant
control inputs to fans and compressors.
Verify airflow for each circuit with all compressors operating fully loaded, for the individual circuit being tested, for a
minimum of 15 minutes in cooling mode. There shall be constant control inputs to fans and compressors.
5.4.2 Measurements; The following coincident measurements shall be made, in accordance with section 1.6.5 of Attachment 1, for the assessment of airflow using this method:
Suction line refrigerant pressure (Pevaporator) at compressor
outlet (preferred)or discharge line refrigerant pressure (Pdischarge) at the compressor outlet.
5.4.3 Calculations and Criteria
5.4.3.1 If measuring discharge pressure instead of liquid line pressure, calculate
Pcondenser as Pdischarge minus 15 psi (or OEM specification for condenser
pressure drop if available).
5.4.3.2 Using the liquid line pressure (Pcondenser), determine the condenser saturation
temperature (Tcondenser) from the standard refrigerant saturated
pressure/temperature chart.
5.4.3.3 Calculate Condensing temperature over ambient (Tcoa) as the condenser
saturation temperature minus the Condenser entering air temperature. Tcoa =
Tcondenser − Toutdoor.
5.4.3.4 The condensing temperature over ambient (Tcoa) must be less than +30� F.
for a valid airflow verification test.
5.4.3.5 Using the suction line pressure (Pevaporator), determine the evaporating
(saturation) temperature (Tevaporator) from the standard refrigerant saturated
5.4.3.6 Calculate Actual Superheat as the suction line temperature minus the evaporator
saturation temperature. Actual Superheat = Tsuction − Tevaporator.
5.4.3.7 For a Non-TxV metering device, determine the Target Superheat using FIGS.
1A and 1B - Table RD-2 or equivalent using the return air wet-bulb temperature
(Treturn, wb) and condenser entering air dry-bulb temperature (Toutdoor, db).
If the test conditions are outside the range of the table, then the test cannot
be used under these conditions. For a TxV metering device, the Target
Superheat is 20� F. or the original equipment manufacturer (OEM) recommended
5.4.3.8 Using the return air wet-bulb temperature (Treturn, wb) and condenser entering
air dry-bulb temperature (Toutdoor, db), determine the target evaporating
temperature using (a) FIG. 3A - Table RD-4a, (b) FIG. 3B - Table RD-4b,
(c) OEM provided equivalent for unit being tested, or (d) alternate method
appropriate for unit being tested that considers variation with return air wet-bulb
temperature (Treturn, wb) and condenser entering air dry-bulb temperature
(Toutdoor, db). If the test conditions are outside the range of FIG. 3A - Table
RD-4a and FIG. 3B - Table RD-4b, then the test cannot be used under these
5.4.3.9 Calculate the difference (DTevap) between actual evaporating temperature and
target evaporating temperature. DTevap = Actual Evaporating Temperature −
Target Evaporating Temperature.
Calculate the difference (DTsh) between actual superheat and target superheat.
DTsh = Actual Superheat − Target Superheat.
For TxV metering device, if DTevap is less than −8� F. (e.g., −12� F.) and DTsh
is less than +5� F., then indoor airflow is low and the system does not pass the
adequate airflow criteria and the airflow shall be increased; otherwise, the test
passes. (In TxV units, the valve may close in response to low airflow to control
superheat near the goal value. The low limit is set to +5� F. to prevent faults that
cause high superheat from being confused with low airflow.)
For non-TxV metering device, if DTevap is less than −5� F. and DTsh is less
than −8� F., then indoor airflow is low and the system does not pass the adequate
airflow criteria, or if DTevap is less than −8� F. and Actual Superheat is less
than 5� F., then indoor airflow is low and the system does not pass the adequate
airflow criteria and the airflow shall be increased; otherwise, the test passes.
Although this invention has been described and illustrated by reference to specific embodiments, it will be apparent to those skilled in the art that various changes, modifications and equivalents may be made which clearly fall within the scope of this invention. The present invention is intended to be protected broadly within the spirit and scope of the appended claim(s).
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS4768346 *Aug 26, 1987Sep 6, 1988Honeywell Inc.Determining the coefficient of performance of a refrigeration systemUS5009076 *Mar 8, 1990Apr 23, 1991Temperature Engineering Corp.Refrigerant loss monitorUS5044168 *Aug 14, 1990Sep 3, 1991Wycoff Lyman WApparatus and method for low refrigerant detectionUS5481884 *Aug 29, 1994Jan 9, 1996General Motors CorporationApparatus and method for providing low refrigerant charge detectionUS5586445 *Sep 30, 1994Dec 24, 1996General Electric CompanyLow refrigerant charge detection using a combined pressure/temperature sensorUS6058719 *Oct 27, 1997May 9, 2000Ecr Technologies, Inc.Heat pump apparatus having refrigerant level indication and associated methodsUS6128910 *Aug 19, 1997Oct 10, 2000Federal Air Conditioning Technologies, Inc.Diagnostic unit for an air conditioning systemUS6176095 *Jan 19, 1999Jan 23, 2001Carrier CorporationPretrip device for testing of a refrigeration system compressorUS6308523 *Mar 20, 2000Oct 30, 2001Mainstream Engineering CorporationSimplified subcooling or superheated indicator and method for air conditioning and other refrigeration systemsUS6571566 *Apr 2, 2002Jun 3, 2003Lennox Manufacturing Inc.Method of determining refrigerant charge level in a space temperature conditioning systemUS6701725 *May 10, 2002Mar 9, 2004Field Diagnostic Services, Inc.Estimating operating parameters of vapor compression cycle equipmentUS6708508 *Dec 11, 2001Mar 23, 2004Behr Gmbh & Co.Method of monitoring refrigerant levelUS6745584Oct 15, 2002Jun 8, 2004Copeland CorporationDigital scroll condensing unit controllerUS6758051Oct 28, 2002Jul 6, 2004Copeland CorporationMethod and system for diagnosing a cooling systemUS6823680Oct 25, 2002Nov 30, 2004Copeland CorporationRemote data acquisition system and methodUS6973793 *Jul 7, 2003Dec 13, 2005Field Diagnostic Services, Inc.Estimating evaporator airflow in vapor compression cycle cooling equipmentUS7032397Dec 31, 2003Apr 25, 2006Emerson Electric Co.Thermostat for use with compressor health indicatorUS7079967 *Dec 2, 2003Jul 18, 2006Field Diagnostic Services, Inc.Apparatus and method for detecting faults and providing diagnostics in vapor compression cycle equipmentUS7100382Apr 30, 2004Sep 5, 2006Emerson Electric Co.Unitary control for air conditioner and/or heat pumpUS7146819 *Feb 10, 2004Dec 12, 2006Behr Gmbh & Co.Method of monitoring refrigerant levelUS7162883Aug 11, 2005Jan 16, 2007Emerson Climate Technologies, Inc.Compressor diagnostic methodUS7174728Jul 30, 2004Feb 13, 2007Emerson Climate Technologies, Inc.Remote data acquisition system and methodUS7201006 *May 17, 2005Apr 10, 2007Lawrence KatesMethod and apparatus for monitoring air-exchange evaporation in a refrigerant-cycle systemUS7222493Dec 6, 2005May 29, 2007Emerson Climate Technologies, Inc.Compressor diagnostic systemUS7240494Jan 30, 2006Jul 10, 2007Emerson Climate Technologies, Inc.Vapor compression circuit and method including a thermoelectric deviceUS7260948Apr 12, 2004Aug 28, 2007Copeland CorporationCompressor diagnostic systemUS7290398Aug 25, 2004Nov 6, 2007Computer Process Controls, Inc.Refrigeration control systemUS7290989Dec 30, 2004Nov 6, 2007Emerson Climate Technologies, Inc.Compressor protection and diagnostic systemUS7296416Jan 30, 2006Nov 20, 2007Emerson Climate Technologies, Inc.Vapor compression circuit and method including a thermoelectric deviceUS7296426Feb 23, 2005Nov 20, 2007Emerson Electric Co.Interactive control system for an HVAC systemUS7313923Jul 24, 2003Jan 1, 2008Emerson Climate Technologies, Inc.Compressor diagnostic system for communicating with an intelligent deviceUS7500368 *Jun 14, 2005Mar 10, 2009Robert James MowrisSystem and method for verifying proper refrigerant and airflow for air conditioners and heat pumps in cooling modeUS7610765 *Nov 3, 2009Carrier CorporationRefrigerant charge status indication method and deviceUS20030019221 *May 10, 2002Jan 30, 2003Rossi Todd M.Estimating operating parameters of vapor compression cycle equipmentUS20040111186 *Dec 4, 2002Jun 10, 2004Rossi Todd M.Apparatus and method for servicing vapor compression cycle equipmentUS20040144106 *Jul 7, 2003Jul 29, 2004Douglas Jonathan D.Estimating evaporator airflow in vapor compression cycle cooling equipmentUS20050126190 *Dec 10, 2003Jun 16, 2005Alexander LifsonLoss of refrigerant charge and expansion valve malfunction detectionUS20050126191 *Dec 10, 2003Jun 16, 2005Alexander LifsonDiagnosing a loss of refrigerant charge in a refrigerant systemUS20060042276 *Aug 25, 2004Mar 2, 2006York International CorporationSystem and method for detecting decreased performance in a refrigeration systemUS20060137370 *Dec 27, 2004Jun 29, 2006Carrier CorporationRefrigerant charge status indication method and deviceUS20070125102 *Dec 5, 2005Jun 7, 2007Carrier CorporationDetection of refrigerant charge adequacy based on multiple temperature measurementsUS20070204635 *Feb 24, 2005Sep 6, 2007Mitsubishi Denki Kabushiki KaishaAir Conditioning Apparatus* Cited by examinerNon-Patent CitationsReference1Carrier Corporation, 1986. Required Superheat Calculator GT24-01 020-434. Syracuse, N.Y.: Carrier Corporation. Shown on p. 80 of publication: Carrier Corporation, 1994 Charging Procedures for Residential Condensing Units.2Carrier Corporation, 1994. Charging Procedures for Residential Condensing Units 020-122, (pp. 78-89), Syracuse, N.Y.: Carrier Corporation.3HVAC Training, Installation & Maintenance Program Technical Specifications. KEMA, Nov. 22, 2006. (Attachment 2 of original Specification).4Title 24 2005 Residential ACM Manual RD-2005, Appendix RD-Procedures for Determining Refrigerant Charge for Split System space cooling systems without Thermostatic Expansion Valves.5Title 24 2005 Residential ACM Manual RD-2005, Appendix RD—Procedures for Determining Refrigerant Charge for Split System space cooling systems without Thermostatic Expansion Valves.6Title 24 2005 Residential ACM Manual RE-2005 Appendix RE-Field Verification and Diagnostic Testing of Forced Air System Fan Flow and Air Handler Fan Watt Draw.7Title 24 2005 Residential ACM Manual RE-2005 Appendix RE—Field Verification and Diagnostic Testing of Forced Air System Fan Flow and Air Handler Fan Watt Draw.8Verified Charge and Airflow Services, Technical Specifications. CSG, 2006. (Attachment 1 of original Specification).Referenced byCiting PatentFiling datePublication dateApplicantTitleUS8583384 *Oct 1, 2010Nov 12, 2013Robert J. MowrisMethod for calculating target temperature split, target superheat, target enthalpy, and energy efficiency ratio improvements for air conditioners and heat pumps in cooling modeUS9207007 *Jan 24, 2013Dec 8, 2015Robert J. MowrisMethod for calculating target temperature split, target superheat, target enthalpy, and energy efficiency ratio improvements for air conditioners and heat pumps in cooling modeUS20110082651 *Oct 1, 2010Apr 7, 2011Mowris Robert JMethod for Calculating Target Temperature Split, Target Superheat, Target Enthalpy, and Energy Efficiency Ratio Improvements for Air Conditioners and Heat Pumps in Cooling Mode* Cited by examinerClassifications U.S. Classification62/127, 62/129International ClassificationF25B49/00Cooperative ClassificationF25B49/005, F25B49/00European ClassificationF25B49/00Legal EventsDateCodeEventDescriptionMay 15, 2008ASAssignmentOwner name: FIELD DIAGNOSTIC SERVICES, INC., PENNSYLVANIAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ROSSI, TODD M.;TEMPLE, KEITH A.;SUN, CHANGLIN;REEL/FRAME:020953/0150;SIGNING DATES FROM 20080318 TO 20080513Owner name: FIELD DIAGNOSTIC SERVICES, INC., PENNSYLVANIAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ROSSI, TODD M.;TEMPLE, KEITH A.;SUN, CHANGLIN;SIGNING DATES FROM 20080318 TO 20080513;REEL/FRAME:020953/0150Mar 11, 2015FPAYFee paymentYear of fee payment: 4RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services