Method for determining evaporator airflow verification

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 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 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 relation of condensing temperature over ambient to a corresponding target parameter determines a valid verification test.

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.

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
• Tcoa=Tcondenser−Toutdoor;
• 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
• Actual Superheat=Tsuction−Tevaporator;
• 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
• DTevap=Actual Evaporating Temperature−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.

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 discharge line refrigerant pressure (Pdischarge) at the compressor outlet;
• calculating Pcondenser as Pdischarge minus 15 psi;
• 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.

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 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
• Tcoa=Tcondenser−Toutdoor;
• 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
• Actual Superheat=Tsuction−Tevaporator;
• 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
• DTevap=Actual Evaporating Temperature−Target Evaporating Temperature;
• p) calculate the difference (DTsh) between actual superheat and target superheat
• DTsh=Actual Superheat−Target Superheat;
• q) compare DTevap to the recommended threshold;
• and
• r) compare DTsh to the recommended threshold.