Performance of dual cycle with variables heats capacity of working fluid

ABSTRACT In this work, the performance of standard air Dual cycle has been studied by using finite time thermodynamics along with determination of temperature and compression ratio, where specific heat capacity at constant volume varies as function of the two later parameters. In this model, the following parameters have been considered: friction loss, heat transfer loss, compression and expansion efficiency, number of the cycle operating in a second, cutoff ratio, pressure ratio, total distance of the piston traveling per cycle and flow rate. A relationship between output power and thermal efficiency of the cycle was derived. From this equation a maximum value was found for each compression ratio. Both output power and thermal efficiency at maximum point decreased with an increase in internal irreversibility. Optimal performance for each irreversible Otto or Diesel cycle can be derived from a dual cycle. Both output power and thermal efficiency at maximum point for Dual cycle decreased with an increase in pressure ratio, friction loss, cutoff ratio, and internal irreversibility. The maximum power output and corresponding thermal efficiency at pressure ratio of 1.5 and the cutoff ratio of 2.4 were found to be 3.32 kW and 0.3687, respectively.