Thermodynamics Review Problems for Mechanical Engineering Students | Series 23: Fifth Series for Diesel Cycle

For this review problem, the very first thing to obtain is the temperature at the end of isentropic compression which is T2 and it can be obtain using the temperature and volume relation during the isentropic compression for which we are provided with compression ratio, rk. By using the relation, we’ve found out that T2 which is at the same time the temperature at the beginning of heat addition process is equal to 705.30°K. Next thing to obtain is the cut-off ratio during the heat addition process, since we aren’t provided with the volumes at this stage, we are going to use both T2 and the maximum temperature of the cycle which is T3. And by using the formula for cut-off ratio which is expressed as a function of temperatures, we’ve found out that rc is equal to 2.84. Finally, we can now obtain the efficiency of the Diesel cycle for which we are going to use the shortcut formula that is expressed as a function of adiabatic index (k), compression ratio (rc) and cut-off ratio (rc). Using the shortcut formula, we’ve found out that the Diesel cycle is 0.4404 ~ 44.04 % efficient.