Predicting the effect of insulation of intake air route of a naturally aspirated XU7 ‎engine in it's performance in an hot and humid weather by thermodynamical ‎modeling

In this research, with the help of thermodynamic modeling of an XU7 engine (manufactured by Irankhodro Co.), the effect of insulation and modification of the intake air route (IAR), in a real hot and humid weather case study(49 ° C and 20.2% relative humidity similar to a normal summer day of Khuzestan state climate) is investigated. In this regard, assuming hot engine run-up and naturally aspiration condition, the thermodynamic model of the processes of a spark ignition engine, based on the Anand combustion model, was developed. In the process of modeling the irreversible work of viscous friction caused by lubrication of pistons and rings, assuming the constant viscosity of the lubricant as well as two compression rings for each piston, was considered. The physical effects of the presence of moisture in the engine intake air(EIA) were taken into account. Considering two different cases, the effect of heat transfer to EIA was applied. Case 1: gradual heat transfer approach along IAR and case 2: heated air suction approach before entering IAR (This approach is closer to reality). The cylinder body temperature as well as the equivalence ratio in the combustion process are considered constant at all crank angular velocities. The results were verified by reputable authorities. The results showed that reducing the EIA temperature due to the insulating IAR is effective for each of the above two cases. But in the second case, this action has a greater impact. Based on the results, the effect of insulating IAR of the XU7 engine in the mentioned weather conditions can be simultaneously, Leads to a 12% increase in engine output power (at 6000 rpm) and also a 10.3% increase in engine output torque (at 1000 rpm).