Map o Sapling Learning macmillan learning At what rate must heat be supplied to
ID: 701072 • Letter: M
Question
Map o Sapling Learning macmillan learning At what rate must heat be supplied to 17.0 kg/s of air, if the temperature is increased from 63.0 to 150 C? a) Calculate the rate that heat must be supplied by integrating the heat capacity formula for air. Number kW b) Calculate the rate that heat must be supplied using the specific enthalpy table of gases located in your text by following the steps below What is the specific enthalpy of air at 63.0, if the reference state is pref-1 atrn, and Tref-25C? Use the specific enthalpy table of gases in your text for this calculation. Number kJ/ mol What is the specific enthalpy of air at 150, if the reference state is pref-1 atm, and Tref-25°C. Use the specific enthalpy table of gases in your text for this calculation. Number k.J/ mol Scroll down for more questions. Calculate the rate that heat must be supplied to 17.0 ka/s or air. O Previous Give Up & View Solution check Answer . Next Exit Y HintExplanation / Answer
We will use the following Cp relation for air
(The above Cp data has been taken from Introduction to Chemical engineering Thermodynamics by Smith Venn Ness 7th edition)
part (a)
Now we will integrate the above CP relation from T = 63 oC and T =150 oC
Specific enthalpy = 2584 J/mol = 2584 /28.97 = 89.1957 J/g = 89.1957 KJ/Kg
mass flow rate of air = 17 Kg/s
Rate of heat supply = 89.1957* 17 = 1516.33 KW
b) Now again we will use the above data and calculate specific enthalpy at 63 oC and at T =150 oC and than subtract to calculate Rate of heat requirement
Specific enthalpy at T =63 oC =1117.56 J/mol = =1.117 KJ/mol
Specific enthalpy at T = 150 oC = 3702.197 J/mol = 3.702 KJ/mol
Change in enthalpy = (3.702 - 1.117) =2.585 KJ/mol = 2.585/28.97 =0.08923 KJ/g =89.2303 KJ/Kg
mass flow rate of air = 17 Kg/s
Rate of heat supply = 89.230*17 = 1516.91 KW
Cp/R = A +BT +CT2 + DT-2 Where T is in K from 298 oK