Effect of humidified intake air on a turbo-charged DICI engine: Performance and emission analysis

Diesel engines have been using extensively in the automotive industry, power generation systems and marine applications. However, diesel engines release massive nitrogen oxides and soot emissions. Several countries or associations have framed very stringent emission regulations for protecting the environment. In this investigation, the effects of different relative humidity (RH) levels; 40, 50, 60, 70 and 80% (approximately) of intake air on the performance and emission parameters of four-stroke single cylinder turbocharged diesel engine have been analyzed. Load (brake power) ranging from 0.5 to 3 kW are varied. Firstly, the experiments are conducted on a conventional diesel engine (CDE); i.e., naturally aspirated condition, assembled turbocharger with CDE and continued with different RH levels. Further, engine performance analysis such as BSFC and BTE are evaluated, and emissions such as CO, HC, NOx and Soot opacity are measured and compared to CDE. The experimental results revealed that BTE, CO and HC emissions are significantly increased while BSFC, NOx, and Soot emissions are decreased as RH levels increase with particular loads as against CDE. For the maximum operated load at 80% RH level, the maximum reductions in BSFC, NOx and Soot emission are achieved as 4.9%, 30.6% and 58.4% respectively, whereas BTE is enhanced by 4.7%. CO and HC emissions are decreased upto the operated load and increased with an increase in the RH level. The maximum reduction in BSFC and increment in HC and CO emissions are achieved at low load compared to peak load operation with an increase in the RH level.