[Code of Federal Regulations]
[Title 40, Volume 17]
[Revised as of July 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR86.344-79]
[Page 616-617]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 86_CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND
ENGINES--Table of Contents
Subpart D_Emission Regulations for New Gasoline-Fueled and Diesel-Fueled
Heavy-Duty Engines; Gaseous Exhaust Test Procedures
Sec. 86.344-79 Humidity calculations.
(a) The following abbreviations (and units) are used in this
section:
BARO = barometric pressure (Pa)
H = specific humidity, (gm H2O/gm of dry air)
K = 0.6220 gm H2O/gm dry air
Mair = Molecular weight of air = 28.9645
MH2O = Molecular weight of water = 18.01534
PDB = Saturation vapor pressure of water at the dry bulb temperature
(Pa)
PDP = saturation vapor pressure of water at the dewpoint temperature
(Pa)
Pv = partial pressure of water vapor (Pa)
PWB = saturation vapor pressure of water at the wet bulb temperature
(pa)
TDB = Dry bulb temperature ([deg]K)
TWB = Wet bulb temperature ([deg]K)
Y = Water-vapor volume concentration
(b) The specific humidity on a dry basis of the intake air (H) is
defined by equation (1).
[GRAPHIC] [TIFF OMITTED] TR06OC93.240
(c) The partial pressure of water vapor may be determined in two
manners:
(1) A dew point device may be used. In that case:
Pv=PDP
(2) A wet-bulb, dry-bulb method may be used. In that case ``Ferrels
equation'' (eq. (2)) is used.
[GRAPHIC] [TIFF OMITTED] TR06OC93.085
(d)(1) The saturation vapor pressure (PWB) of water at the wet-bulb
temperature is defined by equation (3) (Ref. Wexler and Greenspan,
equation (23), National Bureau of Standards).
[GRAPHIC] [TIFF OMITTED] TR06OC93.086
where:
PWB is in Pascals (Pa)
TWB = Web-bulb temperature ([deg]K)
B = - 12.150799
F0 = - 8.49922(10)\3\
F1 = - 7.4231865(10)\3\
F2 = 96.1635147
F3 = 2.4917646(10) -2
F4 = - 1.3160119(10) -5
F5 = - 1.1460454(10) -8
F6 = 2.1701289(10) -11
F7 = - 3.610258(10) -15
F8 = 3.8504519(10) -18
F9 = - 1.4317(10) -21
(2) The table in Figure D79-5 may be used in lieu of equation (3).
(e) The saturated vapor pressure of water at the dry-bulb
temperature (PDB) is found (if required) by using dry-bulb absolute
temperature ([deg]K) in equation (3).
(f) The percent of relative humidity (RH) (if required) is defined
by equation (4).
[GRAPHIC] [TIFF OMITTED] TR06OC93.087
(g) The water-vapor volume concentration on a dry basis of the
engine intake air (Y) is defined by equation (5).
[GRAPHIC] [TIFF OMITTED] TR06OC93.088
Figure D79-5--Saturation Vapor Pressure Over Water (pascals)
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Temperature [deg]C 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
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0................................................... 610.752 615.207 619.690 624.203 628.744 633.315 637.916 642.545 647.205 651.894
1................................................... 656.614 661.364 666.144 670.955 675.796 680.669 685.572 690.507 695.473 700.471
2................................................... 705.500 710.562 715.655 720.781 725.939 731.130 736.354 741.611 746.901 752.224
3................................................... 757.581 762.971 768.396 773.854 779.347 784.874 790.436 796.033 801.664 807.331
4................................................... 813.034 818.771 824.545 830.355 836.200 842.082 848.001 853.956 859.948 865.978
5................................................... 872.045 878.149 884.291 890.470 896.688 902.945 909.239 915.573 921.945 928.357
6................................................... 934.808 941.298 947.828 954.399 961.009 967.660 974.351 981.083 987.856 994.670
7................................................... 1001.53 1008.42 1015.36 1022.34 1029.37 1036.43 1043.54 1050.70 1057.89 1065.13
8................................................... 1072.41 1079.74 1087.11 1094.52 1101.98 1109.48 1117.03 1124.63 1132.27 1139.95
9................................................... 1147.68 1155.46 1163.28 1171.15 1179.07 1187.04 1195.05 1203.11 1211.21 1219.37
10.................................................. 1227.57 1235.83 1244.13 1252.48 1260.88 1269.32 1277.82 1286.37 1294.97 1303.62
11.................................................. 1312.32 1321.07 1329.87 1338.73 1347.63 1356.59 1365.60 1374.67 1383.78 1392.95
[[Page 617]]
12.................................................. 1402.17 1411.45 1420.78 1430.16 1439.60 1449.10 1458.64 1468.25 1477.91 1487.62
13.................................................. 1497.39 1507.22 1517.11 1527.05 1537.04 1547.10 1557.21 1567.39 1577.62 1587.90
14.................................................. 1598.25 1608.66 1619.12 1629.65 1640.24 1650.88 1661.59 1672.36 1683.18 1694.08
15.................................................. 1705.03 1716.04 1727.12 1738.26 1749.46 1760.73 1772.06 1783.45 1794.91 1806.43
16.................................................. 1818.01 1829.67 1841.38 1853.17 1865.02 1876.93 1888.91 1900.96 1913.08 1925.27
17.................................................. 1937.52 1949.84 1962.23 1974.69 1987.21 1999.81 2012.48 2025.21 2038.02 2050.90
18.................................................. 2063.85 2076.87 2089.97 2103.13 2116.37 2129.68 2143.07 2156.53 2170.06 2183.66
19.................................................. 2197.34 2211.10 2224.93 2238.84 2252.82 2266.88 2281.02 2295.23 2309.52 2323.89
20.................................................. 2338.34 2352.86 2367.47 2382.15 2396.91 2411.76 2426.68 2441.68 2456.77 2471.93
21.................................................. 2487.18 2502.51 2517.93 2533.42 2549.00 2564.66 2580.41 2596.24 2612.16 2628.16
22.................................................. 2644.25 2660.42 2676.68 2693.02 2709.46 2725.98 2742.59 2759.28 2776.07 2792.94
23.................................................. 2809.91 2826.96 2844.11 2861.34 2878.67 2896.09 2913.60 2931.20 2948.89 2966.68
24.................................................. 2984.56 3002.54 3020.61 3038.77 3057.03 3075.39 3093.84 3112.39 3131.03 3149.78
25.................................................. 3168.62 3187.55 3206.59 3225.73 3244.96 3264.30 3283.73 3303.27 3322.91 3242.65
26.................................................. 3362.49 3382.43 3402.48 3422.63 3442.89 3463.24 3483.71 3504.28 3524.95 3545.73
27.................................................. 3566.62 3587.62 3608.72 3629.93 3651.25 3672.67 3694.21 3715.86 3737.61 3759.48
28.................................................. 3781.46 3803.55 3825.75 3848.07 3870.50 3893.04 3915.70 3938.47 3961.36 3984.36
29.................................................. 4007.48 4030.71 4054.06 4077.53 4101.12 4124.83 4148.65 4172.59 4196.66 4220.84
30.................................................. 4245.15 4269.58 4294.13 4318.80 4343.60 4368.52 4393.56 4418.73 4444.02 4469.44
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