Explanation Write the chemical reaction equation for the combustion of 1 lbmol methane. C 3 H 8 + 1.4 a th [ O 2 + 3.76 N 2 ] → B CO 2 + D H 2 O + E O 2 + F N 2 (I) Write the expression to calculate the vapor mole fraction ( y v ) . y v = P v , p r o d P p r o d (II) Here, partial pressure of the product is P p r o d , and the partial pressure of water vapor is P v , prod . Write the expression to calculate the vapor mole fraction from number of moles of water vapor ( N water ) . y v = N water N total (III) Here, number of moles of product gas is N total . Calculate the rate of heat transfer from the fuel ( Q ˙ fuel ) . Q ˙ fuel = Q out η (IV) Here, heat transfer from the combustion chamber is Q out , and furnace efficiency is η . Write the steady flow energy balance equation for the combustion of gaseous propane. N ˙ fuel H R = Q ˙ fuel + N ˙ fuel H P (V) Here, number of moles of fuel is N ˙ fuel , enthalpy of products is H P , enthalpy of reactants is H R , and rate of heat transfer is Q ˙ fuel . Write the formula to calculate the molar flow rate of the liquid water ( N ˙ w ) . N ˙ w = N ˙ fuel N w (VI) Here, number of moles of water per kilo mole of fuel is N w . Write the formula to calculate the mass flow rate of water ( m ˙ w ) . m ˙ w = N ˙ w M w (VII) Here, molecular weight of water is M w . Write the formula to calculate the volume flow rate of the liquid water ( V ˙ w ) . V ˙ w = v w m ˙ w (VIII) Here, specific volume of the water is v w . Conclusion: Balance for the carbon from Combustion reaction Equation (I). B = 3 Balance for the hydrogen from Combustion reaction Equation (I). 2 D = 8 D = 4 Balance for the oxygen from Combustion reaction Equation (I). 2 × 1.4 a th = 2 B + D + E (IX) Balance for the excess oxygen from Combustion reaction Equation (I). 0.4 a th = E (X) Substitute 3 for B , 4 for D , and 0.4 a th for E in Equation (IX). 2 × 1.4 a th = 2 ( 3 ) + 4 + 0.4 a th a th = 5 Substitute 5 for a th in Equation (X). 0.4 ( 5 ) = E E = 2 Balance for the nitrogen from Combustion reaction Equation (I). 1.4 a th × 3.76 = F Substitute 5 for a th . 1.4 ( 5 ) × 3.76 = F F = 26.32 Rewrite the chemical reaction equation for the combustion of propane and methane mixture from Equation (I) C 3 H 8 + 1.4 ( 5 ) [ O 2 + 3.76 N 2 ] → ( 3 ) CO 2 + ( 4 ) H 2 O + ( 5 ) O 2 + ( 26.32 ) N 2 C 3 H 8 + 7 [ O 2 + 3.76 N 2 ] → 3 CO 2 + 4 H 2 O + 2 O 2 + 26.32 N 2 (XI) From the table A-4 of “Saturated water: temperature”, obtain the partial pressure of water vapor at saturation temperature of 40 ° C as 7.3851 kPa . Substitute 7.3851 kPa for P v , p r o d , and 100 kPa for P p r o d in Equation (II). y = 7.3851 kPa 100 kPa = 0.07385 Rewrite the Equation (III) of vapor mole fraction for number of moles of water using Equation (XI). y v = 4 − N w 3 + 4 − N w + 2 + 26.32 (XII) Substitute 0.07385 for y v in Equation (XII). 0.07385 = 4 − N w 3 + 4 − N w + 2 + 26.32 N w = 1.503 From the Table A-26 of “Enthalpy of formation, Gibbs function of formation, and absolute entropy at 25 ° C, 1 atm ”, obtain enthalpies of vaporization as, Substance Enthalpy of vaporization h ¯ f o ( kJ / kmol ) C 3 H 8 − 103 , 847 O 2 0 N 2 0 CO 2 − 393 , 520 H 2 O ( g ) − 241 , 820 H 2 O ( l ) − 285 , 830 Write the expression to calculate the enthalpy of reactants ( H R ) from Equation (XI). H R = ( h ¯ f o ) C 3 H 8 + 7 ( h ¯ f o ) O 2 + 26.32 ( h ¯ f o ) N 2 (XIII) Substitute − 103 , 847 kJ / kmol for ( h ¯ f o ) C 3 H 8 , 0 for ( h ¯ f o ) O 2 , and 0 for ( h ¯ f o ) N 2 in Equation (XIII)

8th Edition

ISBN: 8220102809444

Author: CENGEL

Publisher: YUZU

See similar textbooks

Question

Chapter 15.7, Problem 69P

To determine

The volume flow rate of water condensed from the product gases.

Expert Solution & Answer

Want to see the full answer?

Check out a sample textbook solution

See solution

Chapter 15.7, Problem 68P

Chapter 15.7, Problem 70P

Students have asked these similar questions

How do you find these answers?

250 mm 400 mm A B C E F 250 mm PROBLEM 1.52 Each of the two vertical links CF connecting the two horizontal members AD and EG has a 10 × 40-mm uniform rectangular cross section and is made of a steel with an ultimate strength in tension of 400 MPa, while each of the pins at C and F has a 20-mm diameter and are made of a steel with an ultimate strength in shear of 150 MPa. Determine the overall factor of safety for the links CF and the pins connecting them to the horizontal members. 24 kN

50 mm 12 mm B O C OA 300 mm 450 mm E PROBLEM 1.51 Each of the steel links AB and CD is connected to a support and to member BCE by 25-mm-diameter steel pins acting in single shear. Knowing that the ultimate shearing stress is 210 MPa for the steel used in the pins and that the ultimate normal stress is 490 MPa for the steel used in the links, determine the allowable load P if an overall factor of safety of 3.0 is desired. (Note that the links are not reinforced around the pin holes.)

Chapter 15 Solutions

EBK THERMODYNAMICS: AN ENGINEERING APPR

Ch. 15.7 - How does the presence of N2 in air affect the...Ch. 15.7 - Prob. 2P Ch. 15.7 - Prob. 3P Ch. 15.7 - Is the airfuel ratio expressed on a mole basis...Ch. 15.7 - Prob. 5P Ch. 15.7 - Prob. 6P Ch. 15.7 - Prob. 7P Ch. 15.7 - What does 100 percent theoretical air represent?Ch. 15.7 - Consider a fuel that is burned with (a) 130...Ch. 15.7 - Are complete combustion and theoretical combustion...

Knowledge Booster