Analysis of Effect of Tapped Heat from Exhaust Gases using Helical Coiled Heat Exchanger on Engine Performance

Objectives: Recycling the exhaust gas reduces the amount of oxygen after the combustion stroke, resulting in less nitrogen oxide in the exhaust. But the dilution effect of exhaust gas recirculation cannot be neglected as soot emissions increase to undesirable degree. The objective is to tap the heat from the exhaust gas thereby cooling the exhaust which would not only reduce nitrogen oxide content but at the same time pre-heat the intake charge which increases the efficiency of the engine. Methods/Statistical Analysis: Tapping of exhaust heat using a suitable heat exchanger is done by making the exhaust gas pass through one inlet of the helical coiled heat exchanger and atmospheric air in the other such that the air flow is perpendicular to the exhaust flow as the heat exchange rate is better. The temperature gained by the atmospheric air should be regulated and controlled as it can have adverse effects if the atmospheric air exceeds the pre- ignition temperature of the fuel. For this purpose, the exact temperature is to be gained by the atmospheric air required for proper combustion of air fuel mixture is checked with help of C++ program.Design considerations vital for the heat exchanger like effectiveness, area of spiral coil, overall heat transfer coefficient, are also checked with the help of C++ program. Findings: To ensure proper calculations of amount of heat exchanged between exhaust air and fresh inlet air, the properties of metals used for heat exchanger like its thermal conductivity, melting pointetc and dimensional specifications are incorporated in the program. Spirally wound tapered helical coil is compared with helical coil which results in 56% increase in overall heat transfer. Application/Improvements: It is found that there is an increase in the efficiency of the engine by 2.5% and its thermal efficiency by 0.2%. Since the heat exchanger is designed for two - wheelers, theresults of the finding were applied to two different models of two- wheeler i.e. Splender plus and Pulsar and efficiency compared for better understanding.