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Useful Formulas and Conversions

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Useful Formulas and Conversions

Temperature Rise Across a Heat Load

  • Liquid Cooling Systems
  • Air Cooling Systems

    • Conversion Factors

  • Power
  • Temperature
  • Flow
  • Specific Heat
  • Density
  • Pressure

    • Temperature Conversion Chart

  • Temperature Conversion Chart

    •  

    Temperature Rise Across a Heat Load:
    Liquid Cooling Systems

    In a liquid cooled system the heat rise of the coolant across a load can be related to its flow rate and the heat load by the general formula:

    P = F×ΔT×SG×SH×145.7
    or
    ΔT = P/(F×SG×SH×145.7)

    Where:
    P = Power or heat load, in Watts
    F = Flow Rate, GPM
    ΔT = Temperature rise of the coolant, °F
    SG = Specific gravity of the coolant at average coolant temp.
    SH = Specific heat of the coolant at average coolant temp., Btu/(lbm ×°F)

    If the specific gravity and specific heat of the coolant are not known use "K" from the coolant selection chart, assuming 100°F average coolant temperature, in the following formula:

    P = F×ΔT×K
    or
    ΔT = P/(F×K)

     

    Temperature Rise Across a Heat Load:
    Air Cooling Systems

    Air temperature rise across a heat load can be related to the air flow rate and the heat load by a similar formula:

    P = C×ΔT×D×SH×17.58
    or
    ΔT = P/(C×D×SH×17.58)

    Where:
    P = Power or heat load, in Watts
    C = Flow Rate, CFM
    ΔT = Temperature rise of the air, °F
    D = Density of the air at average temp., lbm/ft³
    SH = Specific heat of the air at average temp., Btu/(lbm ×°F)

    If the density and specific heat of the air are not known use "K" from the coolant selection chart, assuming 70°F average air temperature at sea level, in the following formula:

    P = C×ΔT×K
    or
    ΔT = P/(C×K)

     

    Power Conversion Factors

    1W = 3.413 Btu/hr
    1HP = 745.7 W

     

    Temperature Conversion Factors

    °C = (°F-32) × (5/9)
    °F = °C × (9/5) + 32

     

    Flow Conversion Factors

    1 LPM = .264 GPM

     

    Specific Heat Conversion Factors

    1kj/(kg × °C) = .23885 Btu/(lbm × °F)

     

    Density Conversion Factors

    1kg/m³ = .062428 lbm/ft³

     

    Pressure Conversion Factors

    1kPa = .145 psi
    1 psi = 2.307 ft head

     

    Temperature Conversion Chart

    How to use this temperature conversion chart:

    Blue numbers refer to temperature (in degrees Celsius or Fahrenheit) which it is desired to convert into the other scale. When converting from Fahrenheit to Centigrade read equivalent temperature in left column. When converting from Centigrade to Fahrenheit find equivalent temperature in right column. Temperatures not listed may be determined using the formulas found at the following link: Temperature Conversion Factor.

    °C

    °F
    °C

    °F
    °C

    °F
    -56.7
    -51.1
    -45.6
    -40.0
    -39.4
    -70
    -60
    -50
    -40
    -39
    -94.0
    -76.0
    -58.0
    -40.0
    -38.2
    -1.1
    -0.6
    0.0
    0.6
    1.1
    30
    31
    32
    33
    34
    86.0
    87.8
    89.6
    91.4
    93.2
    46.1
    48.9
    51.7
    54.4
    57.2
    115
    120
    125
    130
    135
    239.0
    248.0
    257.0
    266.0
    275.0
    -38.9
    -38.3
    -37.8
    -37.2
    -36.7
    -38
    -37
    -36
    -35
    -34
    -36.4
    -34.6
    -32.8
    -31.0
    -29.2
    1.7
    2.2
    2.8
    3.3
    3.9
    35
    36
    37
    38
    39
    95.0
    96.8
    98.6
    100.4
    102.2
    60.0
    62.8
    65.6
    68.3
    71.1
    140
    145
    150
    155
    160
    284.0
    293.0
    302.0
    311.0
    320.0
    -36.1
    -35.6
    -35.0
    -34.4
    -33.9
    -33
    -32
    -31
    -30
    -29
    -27.4
    -25.6
    -23.8
    -22.0
    -20.2
    4.4
    5.0
    5.6
    6.1
    6.7
    40
    41
    42
    43
    44
    104.0
    105.8
    107.6
    109.4
    111.2
    73.9
    76.7
    79.4
    82.2
    85.0
    165
    170
    175
    180
    185
    329.0
    338.0
    347.0
    356.0
    365.0
    -33.3
    -32.8
    -32.2
    -31.7
    -31.1
    -28
    -27
    -26
    -25
    -24
    -18.4
    -16.6
    -14.8
    -13.0
    -11.2
    7.2
    7.8
    8.3
    8.9
    9.4
    45
    46
    47
    48
    49
    113.0
    114.8
    116.6
    118.4
    120.2
    87.8
    90.6
    93.3
    96.1
    98.9
    190
    195
    200
    205
    210
    374.0
    383.0
    392.0
    401.0
    410.0
    -30.6
    -30.0
    -29.4
    -28.9
    -28.3
    -23
    -22
    -21
    -20
    -19
    -9.4
    -7.6
    -5.8
    -4.0
    -2.2
    10.0
    10.6
    11.1
    11.7
    12.2
    50
    51
    52
    53
    54
    122.0
    123.8
    125.6
    127.4
    129.2
    101.7
    104.4
    107.2
    110.0
    112.8
    215
    220
    225
    230
    235
    419.0
    428.0
    437.0
    446.0
    455.0
    -27.8
    -27.2
    -26.7
    -26.1
    -25.6
    -18
    -17
    -16
    -15
    -14
    -0.4
    1.4
    3.2
    5.0
    6.8
    12.8
    13.3
    13.9
    14.4
    15.0
    55
    56
    57
    58
    59
    131.0
    132.8
    134.6
    136.4
    138.2
    115.6
    118.3
    121.1
    123.9
    126.7
    240
    245
    250
    255
    260
    464.0
    473.0
    482.0
    491.0
    500.0
    -25.0
    -24.4
    -23.9
    -23.3
    -22.8
    -13
    -12
    -11
    -10
    -9
    8.6
    10.4
    12.2
    14.0
    15.8
    15.6
    16.1
    16.7
    17.2
    17.8
    60
    61
    62
    63
    64
    140.0
    141.8
    143.6
    145.4
    147.2
    129.4
    132.2
    135.0
    137.8
    140.6
    265
    270
    275
    280
    285
    509.0
    518.0
    527.0
    536.0
    545.0
    -22.2
    -21.7
    -21.1
    -20.6
    -20.0
    -8
    -7
    -6
    -5
    -4
    17.6
    19.4
    21.2
    23.0
    24.8
    18.3
    18.9
    19.4
    20.0
    20.6
    65
    66
    67
    68
    69
    149.0
    150.8
    152.6
    154.4
    156.2
    143.3
    146.1
    148.9
    154.4
    160.0
    290
    295
    300
    310
    320
    554.0
    563.0
    572.0
    590.0
    608.0
    -19.4
    -18.9
    -18.3
    -17.8
    -17.2
    -3
    -2
    -1
    0
    1
    26.6
    28.4
    30.2
    32.0
    33.8
    21.1
    21.7
    22.2
    22.8
    23.3
    70
    71
    72
    73
    74
    158.0
    159.8
    161.6
    163.4
    165.2
    165.6
    171.1
    176.7
    182.2
    187.8
    330
    340
    350
    360
    370
    626.0
    644.0
    662.0
    680.0
    698.0
    -16.7
    -16.1
    -15.6
    -15.0
    -14.4
    2
    3
    4
    5
    6
    35.6
    37.4
    39.2
    41.0
    42.8
    23.9
    24.4
    25.0
    25.6
    26.1
    75
    76
    77
    78
    79
    167.0
    168.8
    170.6
    172.4
    174.2
    193.3
    198.9
    204.4
    210.0
    215.6
    380
    390
    400
    410
    420
    716.0
    734.0
    752.0
    770.0
    788.0
    -13.9
    -13.3
    -12.8
    -12.2
    -11.7
    7
    8
    9
    10
    11
    44.6
    46.4
    48.2
    50.0
    51.8
    26.7
    27.2
    27.8
    28.3
    28.9
    80
    81
    82
    83
    84
    176.0
    177.8
    179.6
    181.4
    183.2
    221.1
    226.7
    232.2
    237.8
    243.3
    430
    440
    450
    460
    470
    806.0
    824.0
    842.0
    860.0
    878.0
    -11.1
    -10.6
    -10.0
    -9.4
    -8.9
    12
    13
    14
    15
    16
    53.6
    55.4
    57.2
    59.0
    60.8
    29.4
    30.0
    30.6
    31.1
    31.7
    85
    86
    87
    88
    89
    185.0
    186.8
    188.6
    190.4
    192.2
    248.9
    254.4
    260.0
    265.6
    271.1
    480
    490
    500
    510
    520
    896.0
    914.0
    932.0
    950.0
    968.0
    -8.3
    -7.8
    -7.2
    -6.7
    -6.1
    17
    18
    19
    20
    21
    62.6
    64.4
    66.2
    68.0
    69.8
    32.2
    32.8
    33.3
    33.9
    34.4
    90
    91
    92
    93
    94
    194.0
    195.8
    197.6
    199.4
    201.2
    276.7
    282.2
    287.8
    293.3
    298.9
    530
    540
    550
    560
    570
    986.0
    1004.0
    1022.0
    1040.0
    1058.0
    -5.6
    -5.0
    -4.4
    -3.9
    -3.3
    22
    23
    24
    25
    26
    71.6
    73.4
    75.2
    77.0
    78.8
    35.0
    35.6
    36.1
    36.7
    37.2
    95
    96
    97
    98
    99
    203.0
    204.8
    206.6
    208.4
    210.2
    304.4
    310.0
    315.6
    321.1
    326.7
    580
    590
    600
    610
    620
    1076.0
    1094.0
    1112.0
    1130.0
    1148.0
    -2.8
    -2.2
    -1.7
    27
    28
    29
    80.6
    82.4
    84.2
    37.8
    40.6
    43.3
    100
    105
    110
    212.0
    221.0
    230.0
    332.2
    337.8
    343.3
    630
    640
    650
    1166.0
    1184.0
    1202.0

    While every precaution has been taken to ensure accuracy and completeness in this catalog, Electro Impulse Laboratory, Inc. assumes no responsibility, and disclaims all liability for damages resulting from use of this information or for any errors or omissions.


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