1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
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4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J1487_201301 SURFACE VEHICLE RECOMMENDED PRACTICE J1487 JAN2013 Issued 1985-05 Re
5、vised 2013-01 Superseding J1487 SEP2004 Rating Air-Conditioner Evaporator Air Delivery and Cooling Capacities RATIONALE Chamber settling screen density was increased so uniform velocity is established ahead of the nozzles. 1. SCOPE The purpose of this SAE Recommended Practice is to establish uniform
6、 test procedures for measuring and rating air delivery and cooling capacity of truck and off-road self-propelled work machines used in earth moving, agriculture, and forestry air-conditioner evaporator assemblies. It is the intent to measure only the actual cooling capacity of the evaporator. It is
7、not the intent of this document to rate and compare the performance of the total vehicle air-conditioning system. 1.1 This procedure is designed to provide truck and off-road self-propelled work machines used in earth moving, agriculture, and forestry manufacturers and air conditioning system suppli
8、ers with a cost-effective, standardized test method and calculations for measuring and rating air delivery and cooling capacity of truck cab air-conditioner evaporator assemblies. This procedure relates to HFC-134a (R-134a) refrigerant system. 2. REFERENCES There are no referenced publications speci
9、fied herein. 3. DEFINITIONS 3.1 EVAPORATOR ASSEMBLY The evaporator assembly as defined consists of a coil (heat transfer surface), the means of forcing air over the heat transfer surface into the cab, and the complete enclosure (air conditioning unit) to be furnished for the installation. 3.2 REFRIG
10、ERANT CONTROL The device furnished with the evaporator assembly to regulate the flow of refrigerant into the coil. It is to be the control specified and included with the evaporator assembly being tested. SAE J1487 Revised JAN2013 Page 2 of 16 3.3 EVAPORATOR ASSEMBLY CAPACITY 3.3.1 Air Delivery Rate
11、 The actual rate of airflow SCFM (standard air volume flow rate as specified in 8.1) for wet coil conditions. The air delivery is to be measured during the Capacity Rating Test in Section 7. 3.3.2 Cooling Capacity (air side) The amount of heat absorbed from the air flowing through the evaporator in
12、W, kW (Btu/hour), as specified in 8.3 and 8.4. 3.3.3 Cooling Capacity (refrigerant side) The amount of heat absorbed by refrigerant flowing through the evaporator tubes in W, kW (Btu/hour), as specified in Section 9. 3.4 DRY BULB TEMPERATURE Air temperature in C (F) as read from a standard thermomet
13、er or other appropriate temperature measuring device. 3.5 WET BULB TEMPERATURE Air temperature in C (F) essentially equal to that read from a wet bulb thermometer, or one whose sensing bulb is covered by a water-wetted wick located in the moving air stream. 3.6 RELATIVE HUMIDITY Ratio of the amount
14、of moisture (in mol-fraction) in the air to the maximum amount the air can hold at the same temperature and pressure. 3.7 HUMIDITY RATIO Ratio of the mass of water vapor to the mass of dry air kgw/kga(lbw/lba). 3.8 DEW POINT (SATURATION) TEMPERATURE Air temperature in C (F) at which moisture begins
15、to condense out as the air is cooled at constant pressure. 3.9 TOTAL HEAT (ENTHALPY) The total heat content (sensible and latent) in the air j/kga(Btu/lba) equal to the sum of the individual partial enthalpies of the dry air and water vapor. 3.10 SENSIBLE HEAT The amount of heat associated with a ch
16、ange in the dry bulb temperature of the air. SAE J1487 Revised JAN2013 Page 3 of 16 3.11 LATENT HEAT The amount of heat required to change the state of a substance. Specifically, it is the heat released as water vapor condenses out of moist air, and also the heat associated with the phase change of
17、certain heat transfer fluids (volatile refrigerants, steam, etc.). 3.12 DISCHARGE LINE High pressure (inlet line) that carries liquid Refrigerant to the expansion device. 3.13 SUCTION LINE Low pressure (outlet line) that carries evaporated (gaseous) Refrigerant to the compressor. 3.14 SUBCOOLING The
18、 degrees of temperature below the saturation temperature (based on the inlet pressure of expansion device) of the liquid Refrigerant C (F). 3.15 SUPERHEAT The degrees of temperature above the saturation temperature (based on the outlet pressure of the evaporator) of the vaporized Refrigerant C (F).
19、3.16 EXPANSION DEVICE Valve or fixed orifice in the Refrigerant circuit whose purpose is to meter refrigerant into the evaporator inducing a large pressure-drop causing a change of state. 3.17 COMPRESSOR Pumps low pressure Refrigerant vapor out of the evaporator by suction, raises its pressure, and
20、then pumps it, under high pressure, into the condenser. 3.18 CONDENSER Removes heat from the entering high pressure, high temperature de-superheated Refrigerant vapor changing it to a high pressure, high temperature liquid. 3.19 EVAPORATOR Removes unwanted heat from the air by the boiling of liquid
21、Refrigerant in the evaporator coil. 3.20 PSYCHROMETRIC CHART Graphical presentation of moist air properties. 3.21 RESISTANCE TEMPERATURE DEVICE (RTD) Used for precision measurement of refrigerant temperature for purpose of capacity calculations. SAE J1487 Revised JAN2013 Page 4 of 16 4. SYMBOLS AND
22、UNITS A = Area in m2(ft2) AN= Area of Nozzle in m2(ft2) BP = Barometric Pressure (Absolute) in Pa (in of Hg) Cp.a= Specific Heat of the Air in j/(kg*K) (Btu/lb/F) CFM = Air Volume Flow Rate in m3/min (Cubic Feet per Minute, CFM) at the Air Density Calculated for the Conditions Existing at the Air Me
23、asurement Nozzle D = Diameter in m (inches or feet) DB = Dry Bulb in C (F) DC = Direct Current, amp DN = Diameter of Nozzle, m2(ft2) dn = Density of Air at the Nozzle in kg/m3(lb/ft3) G = Mass Flow Rate of the Air (kg/s, sometimes kg/hour (lb/hour) kga/s, kgmix/s, kgw/s; (lba/hour, lbmix/hour, and l
24、bw/hour) = air mass flow of the dry air, moist air - air-water vapor mixture, and water vapor Gr= Mass Flow Rate of the Refrigerant in kg/hour (lb/min) Hg = Mercury h = Enthalpy (Change in Heat Content), j/kg (Btu/lb) in = inches NT= Air Temp DB at Nozzle C (F) PD = Pressure Differential Pa (psi) Qr
25、 = Total Heat Transferred (Total Cooling Capacity), refrigerant side in kW (Btu/hour) Qs= Sensible Heat Transferred (Sensible Cooling Capacity), air side in kW (Btu/hour) Qt= Total Heat Transferred (Total Cooling Capacity), air side in kW (Btu/hour) SCFM = Air Volume Flow Rate in Standard Cubic Feet
26、 per Minute Based on1.20 kg/m3(0.075 lb/ft3) for Dry Air at 21 C (70 F) and 101.04 kPa (29.92 in Hg) (see detailed explanation in 8.1.2) SP = Static Pressure, Pa (psig) T = Temperature in C (F) V = Velocity in m/min (feet per minute, FPM) W = Air Humidity Ratio in kgw/kga(lbw/lba) WB = Wet Bulb, C (
27、F) WG = Water Gauge in mm (inches) 5. TEST EQUIPMENT 5.1 Test Room (Calorimeter Room) A room in which specified ambient test conditions can be maintained to supply a controlled ambient for the evaporator assembly with constant inlet DB and WB as specified in 6.4. 5.2 A means of measuring airflow suc
28、h as described in 5.2.1 through 5.2.3, or any other device of equivalent accuracy that does not interfere with the intent of the test: 5.2.1 Airflow Measurement Chamber (Air Booth) See Figure 1. SAE J1487 Revised JAN2013 Page 5 of 16 5.2.2 Nozzle See Figure 3. The nozzle throat shall be measured on
29、four diameters at 45 degree intervals, to an accuracy of 0.001 D and shall not deviate more than 0.002 D from the mean. Measurements shall also be made on the inlet of the parallel section which may be +0.002 D greater than the exit, but no less. The nozzle surface must be smooth with surface waves
30、no greater than 0.001 D peak-to-peak. Recommended construction is spun aluminum, and the dimension D can be calculated from 8.3 based on anticipated air flow measurement requirements. NOTE: Minimum acceptable nozzle PD shall be 99.5 Pa (0.4 in WG). 5.2.3 Inclined Manometers Inclined manometers used
31、in conjunction with 5.2 shall have a scale expansion factor of at least 10 distance between 0 to 249 Pa (0 and 1 “in WG) to be at least 25.4 cm (10 in) with scale divisions of 2.49 Pa (0.01 in WG) maximum for pressures below 498 Pa (2 in WG) and 12.4 Pa (0.05 in WG) maximum scale divisions for press
32、ures above 498 Pa (2 in WG). Micromanometers may be used in place of the inclined manometers. SAE J1487 Revised JAN2013 Page 6 of 16 FIGURE 1 - AIR MEASUREMENT CHAMBER SAE J1487 Revised JAN2013 Page 7 of 16 FIGURE 2 - PIEZOMETER RING FIGURE 3 - NOZZLE SAE J1487 Revised JAN2013 Page 8 of 16 5.3 Tempe
33、rature and Humidity Measurement Instrumentation 5.3.1 Air dry bulb temperatures are to be measured with an accuracy of 0.3 C (0.5 F). The temperature measurements may be made with precision thermometers, thermocouples, or RTDs with the measurement device having a minimum resolution and certified acc
34、uracy of 0.3 C (0.5 F). 5.3.2 Wet bulb temperatures are to be measured with a certified accuracy and minimum resolution of 0.1 C (0.2 F). The wet bulb temperatures are to be made with precision wet bulb thermometers and air sampling device (shown in Figure 4) to obtain an average air sample and prov
35、ide a minimum velocity of 305 m/min (1000 FPM) over the bulb. FIGURE 4 - WET BULB SAMPLER 5.3.3 Dew Point Temperatures are to be measured with a certified accuracy and minimum resolution of 0.1 C (0.2 F). The dew point temperatures are to be made with precision chilled mirror or other similar device
36、. 5.3.4 Relative Humidity (RH) is to be measured with a certified accuracy of g1002% of the rate. The RH is to be made with precision relative humidity measuring device. 5.3.5 Refrigerant Temperatures are to be measured with a certified accuracy of 0.1 C (0.2 F). The refrigerant temperatures are to
37、be made with precision RTDs that immerse into appropriate refrigerant line by means of temperature tap. RTDs have to be installed on the liquid and suction lines as close as possible to the evaporator core but not further than 15.4 cm (6 in) from evaporator (expansion device). 5.4 Refrigerant pressu
38、re gauges or pressure transducers with a minimum resolution and certified accuracy of 3.45 kPa (0.5 psi) for evaporator suction pressure measurements and 6.89 kPa (1.0 psi) for the pressure measurement at the inlet to the refrigerant control per 3.2. Pressure measuring devices have to be installed o
39、n the liquid and suction lines by means of pressure tap as close as possible to the evaporator core but not further than 15.4 cm (6 in) from evaporator (expansion device). 5.5 Condenser of sufficient capacity to maintain the conditions specified in 6.5. 5.6 Compressor to be of sufficient capacity to
40、 maintain the conditions as specified in 6.6. 5.7 DC voltmeter with a minimum resolution and certified accuracy of 0.1 V. 5.8 DC ammeter with a minimum resolution and certified accuracy of 0.2 amp. 5.9 Mercury barometer with vernier scale to provide 67.5 Pa (0.02 in Hg) minimum resolution. SAE J1487
41、 Revised JAN2013 Page 9 of 16 5.10 Refrigerant Mass Flow Rate are to be measured with a minimum resolution and certified accuracy of 0.15% of the rate by means of precision refrigerant flow meter (for example, MicroMotion mass flow meter, model Elite) 6. TEST CONDITIONS 6.1 The evaporator blower is
42、to be operating on high speed, the fresh air inlet control is to be in fresh air mode, and the outlet air control is to be set to the air-conditioning mode. 6.2 The voltage input shall be the nominal voltage 0.1 V measured at the blower motor leads (at a maximum of 15.4 cm (6 in) from the motor); i.
43、e., 12.0 V 0.1 for 12.0 V systems. Referencing the voltage to the motor leads is necessary to eliminate the variations in input voltage caused by different wire harness sizes and other variable voltage losses between the vehicle power source and the blower motor. 6.3 The evaporator assembly outlet a
44、ir is to discharge to the airflow measurement chamber plenum, and the variable speed exhaust fan is to be adjusted to maintain 0 Pa (0 in WG) SP through 498 Pa (2.0 in WG) SP at 124 Pa (0.50 in) increments in the plenum with 12.0 V input to the evaporator blower motor. 6.4 The ambient air in the tes
45、t room is to be maintained at 26.7 C (80 F ) DB 0.6 C (1 F ) and 19.4 C WB (67 F) 0.3 C (0.5 F), which is 50% 1.5% of RH and 14.4 C (58 F) 0.6 C (1 F) of Dew Point Temperature. This is the air supply to the evaporator assembly inlet. 6.5 The condenser capacity is to be adjusted to maintain refrigera
46、nt subcooling of 5 C to 7 C (9 F to 12 F) at 1380 kPa 34 kPa (200 psig 5 psig) at the refrigerant control in 3.2. The refrigerant pressure and temperature are to be measured as close as possible but not further than 15.4 cm (6 in) from the refrigerant control inlet. 6.6 The compressor capacity (spee
47、d) is to be adjusted to maintain an average of 207 kPa 3.47 kPa (30 psig 0.5 psi) at the evaporator suction line outlet. The pressure is to be as close as possible but not further than 15.4 cm (6 in) from the evaporator suction line outlet. 6.7 With evaporator assembly enclosures containing a heater
48、 core that requires no water valve shutoff, a water temperature of 82.2 C (180 F) at the core inlet should be maintained with a flow rate of 816.6 kg/hour (30 lb/min). 7. TEST PROCEDURE 7.1 One very important condition that must be satisfied during the testing process when measurements are taken is
49、that the air/refrigerant heat transfer balance should be within 3%. During vehicle HVAC system operations, the airside heat transfer is balanced on the tubeside of the coil with an equal amount of heat being either absorbed or given up by the fluid flowing through the tubes. So, the measuring procedure should begin only after stable air/refrigerant
