The constant-pressure specific heat of air at 25 ° C in kJ / kg ⋅ K , J / g ° C , kcal / kg ⋅ ° C and Btu / lbm ⋅ ° F .

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Answer 1

Question

Chapter 1.11, Problem 11P

To determine

The constant-pressure specific heat of air at 25°C in kJ/kg⋅K, J/g°C, kcal/kg⋅°C and Btu/lbm⋅°F.

Expert Solution & Answer

Answer to Problem 11P

The constant-pressure specific heat of air at 25°C in kJ/kg⋅K, J/g°C, kcal/kg⋅°C and Btu/lbm⋅°F are 1.005 kJ/kg⋅K, 1.005 J/g°C, 0.240 kcal/kg⋅°C and 0.240 Btu/lbm⋅°F respectively.

Explanation of Solution

Write the expression of conversion relation for the constant-pressure specific heat of air from kJ/kg⋅°C to kJ/kg⋅K.

cp(kJ/kg⋅°C)=cp(kJ/kg⋅°C)×1 kJ/kg⋅K1 kJ/kg⋅°C=cp(kJ/kg⋅K)

Write the expression of conversion relation for the constant-pressure specific heat of air from kJ/kg⋅°C to J/g°C.

cp(kJ/kg⋅°C)=cp(kJ/kg⋅°C)×1000 J1 kJ×1 kg1000 g=cp(J/g°C)

Write the expression of conversion relation for the constant-pressure specific heat of air from kJ/kg⋅°C to kcal/kg⋅°C.

cp(kJ/kg⋅°C)=cp(kJ/kg⋅°C)×1 kcal4.1868 kJ=cp(kcal/kg⋅°C)

Write the expression of conversion relation for the constant-pressure specific heat of air from kJ/kg⋅°C to Btu/lbm⋅°F.

cp(kJ/kg⋅°C)=cp(kJ/kg⋅°C)×1 Btu/lbm⋅°F4.1868 kJ/kg⋅°C=cp(Btu/lbm⋅°F)

Conclusion:

Convert the unit of constant-pressure specific heat of air from kJ/kg⋅°C to kJ/kg⋅K at 25°C.

cp=1.005 kJ/kg⋅°C=1.005 kJ/kg⋅°C×1 kJ/kg⋅°C1 kJ/kg⋅K=1.005 kJ/kg⋅K.

Convert the unit of constant-pressure specific heat of air from kJ/kg⋅°C to J/g°C at 25°C.

cp=1.005 kJ/kg⋅°C=1.005 kJ/kg⋅°C×1000 J1 kJ×1 kg1000 g=1.005 J/g°C

Convert the unit of constant-pressure specific heat of air from kJ/kg⋅°C to kcal/kg⋅°C at 25°C.

cp=1.005 kJ/kg⋅°C=1.005 kJ/kg⋅°C×1 kcal4.1868 kJ=0.240 kcal/kg⋅°C

Convert the unit of constant-pressure specific heat of air from kJ/kg⋅°C to Btu/lbm⋅°F at 25°C.

cp=1.005 kJ/kg⋅°C=1.005 kJ/kg⋅°C×1 Btu/lbm⋅°F4.1868 kJ/kg⋅°C=0.240 Btu/lbm⋅°F

Thus, the constant-pressure specific heat of air at 25°C in kJ/kg⋅K, J/g°C, kcal/kg⋅°C and Btu/lbm⋅°F are 1.005 kJ/kg⋅K, 1.005 J/g°C, 0.240 kcal/kg⋅°C and 0.240 Btu/lbm⋅°F respectively.

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