Question

For air, at 35°C what is the total enthalpy? (cp=1005 \(\frac {J}{kgK}\)).

(a) Zero

(b) 309.54 J

(c) 309.54 kJ

(d) 8977 J

I have been asked this question in an online quiz.

I need to ask this question from A Brief Review of Thermodynamics in division Compressible Flow – Preliminary Aspects of Aerodynamics

Answer 1

The correct option is (d) 8977 J

The explanation: The specific enthalpy (h) is given as h=cpT where T is in Kelvin. This is the enthalpy per unit mass. For total enthalpy of the air, we need to multiply h by the molecular mass of air i.e. H=29h which gives total enthalpy equal to 8977 J, irrespective of the process.