Page 22 - Aeronautical Engineer Data Book

12 Aeronautical Engineer’s Data Book
Volume

0 K
–273.15˚C 0˚C 100˚C
32˚F 212˚F
Fig. 2.3 Temperature

2.3.6 Heat and work
The basic unit for heat ‘energy’ is the British
thermal unit (BTU).
Specific heat ‘energy’ is measured in BTU/lb
(in SI it is joules per kilogram (J/kg)).
–3
1 J/kg = 0.429923 2 10 BTU/lb
Table 2.6 shows common conversions.
Specific heat is measured in BTU/lb °F (or in
SI, joules per kilogram kelvin (J/kg K)).
1 BTU/lb °F = 4186.798 J/kg K
–3
1 J/kg K = 0.238846 ( 10 BTU/lb °F
1 kcal/kg K = 4186.8 J/kg K
Heat flowrate is also defined as power, with the
unit of BTU/h (or in SI, in watts (W)).
1 BTU/h = 0.07 cal/s = 0.293 W
1 W = 3.41214 BTU/h = 0.238846 cal/s

2.3.7 Power
BTU/h or horsepower (hp) are normally used
or, in SI, kilowatts (kW). See Table 2.7.

2.3.8 Flow
The basic unit of volume flowrate is US
gallon/min (in SI it is litres/s).
1 US gallon = 4 quarts = 128 US fluid ounces
= 231 in 3