Final answer:
To calculate the percentage change in efficiency of a Diesel cycle, calculate the initial efficiency, then the final efficiency using the modified specific heat value, and finally find the percentage change.
Step-by-step explanation:
In order to calculate the percentage change in efficiency of a Diesel cycle, we first need to calculate the initial efficiency and then the final efficiency. The efficiency of a Diesel cycle is given by the formula:
Efficiency = 1 - (1/r)^(γ-1)
Where r is the compression ratio and γ is the ratio of specific heats.
To calculate the initial efficiency, we substitute the initial values into the formula and solve for the initial efficiency. Then we calculate the final efficiency using the modified specific heat value. Once we have both the initial and final efficiencies, we can calculate the percentage change in efficiency using the formula:
Percentage Change in Efficiency = ((Final Efficiency - Initial Efficiency) / Initial Efficiency) * 100
The question refers to the efficiency change of a Diesel cycle when there is a specific increase in the specific heat at constant volume (Cv). Since Cv affects the heat absorbed and rejected during the cycle, a change in Cv will influence the overall efficiency of the cycle. However, to calculate the exact percentage change in efficiency, it would require the use of thermodynamic equations related to the Diesel cycle, which are not provided in this context. Typically, such calculations would involve formulas that account for the compression ratio, cut-off ratio, properties of the working fluid (like specific heats Cp and Cv), and the ideal gas constant R. Without these, the percentage change in efficiency cannot be determined.