Consider a Diesel cycle that starts (at point a in Fig. 20.7) with air at temperature Ta. The air may be treated as an ideal gas. (a) If the temperature at point c is Tc, derive an expression for the efficiency of the cycle in terms of the compression ratio r. (b) What is the efficiency if Ta = 300 K, Tc = 950 K, ? = 1.40, and r = 21.0?

Solution 64CP Step 1: A)The analysis results in the following three general forms representing an adiabatic Process PV diagram T vk1= constant T p(1k)/kconstant P vk = constant where k is the ratio of heat capacities and has a nominal value of 1.4 at 300K for air.