High-Velocity Gas Flow with Friction, Heating, or Both

4 HIGH-VELOCITY GAS FLOW WITH FRICTION, HEATING, OR BOTH 

In previous sections we omitted the possible influence of friction, heat transfer from the surroundings to the flowing gas, and chemical reaction (such as 

Rather thani develop the complete mathematics of these flows here, we simply indicate s ome of the salient results, referring the. reader to other sources, where the complete mathematics are shown. We concentrate on the two types of flow of most practical interest to chemical engineers. 

This type of flov occurs when a gas flows through a length of pipe at high velocity. If the pipe is insulated or the flow is rapid, the heat transfer to the fluid will be negligible and the flow will be practically adiabatic. 

For this type of flow, the mass balance, energy, and perfect-gas equations take the same form as for steady, isentropic flow of a perfect gas. However, in Sec. 8,2 we used the isentropic relations from App. D here we cannot, because the effect of friction is to increase the entropy of the flowing gas. In their place we use the momentum balance (Eq. 7.13), written for two points dx 

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