Investigating the performance and emission characteristics of diesel-LPG engine operation

Student thesis: Doctoral Thesis

Abstract

In the last couple of decades, attention has been placed on reducing atmospheric emissions globally, including the enforcement of stricter requirements which target emissions from internal combustion engines. This is not surprising considering the spate of public attention about the health impacts of atmospheric pollution. Then again there are concerns about their environmental impact. Consequently, engine developers, end-users, and researchers, increasingly are reconsidering the century-long idea of dual fuel engines. While there have been successful attempts to develop viable, sustainable alternatives to power diesel engines, the extent to which engine performance and emissions may be affected remains unknown. Therefore, this study evaluates the performance and emission characteristics of a diesel engine modified to run simultaneously with diesel and liquefied petroleum gas (LPG). The aim of this research is to numerically investigate the performance and emission characteristics associated with dual fuel engine operation (wherein LPG and diesel fuels are simultaneously used) with regards to the diesel engine operation at various operating regimes, taking into consideration different fuel mass ratios. With this in mind, this study presents a one-dimensional model developed using AVL BOOST to simulate the diesel and diesel-LPG engine operational modes. The model is calibrated using the peak cylinder pressure, the timing of the peak cylinder pressure, power and torque. For the maximum LPG scenario (70% diesel and 30% LPG) investigated at 2435 rpm, compared to the diesel engine operation, the maximum cylinder pressure was shown to increase from 77.16 bar to 93.42 bar representing an increase of 21.07%. Additionally, at 2435 rpm, the results from the study suggest a fairly linear increment in power when LPG mass ratio in the diesel-LPG fuel mixture is increased from 10 to 30%.It is remarkable that the highest mass ratio of LPG used in the diesel-LPG fuel mixture produces the highest brake thermal efficiency at 2435 rpm. Regardless of the speed, increasing the LPG fuel mass ratio in the diesel-LPG fuel mixture leads to a reduction in the nitrogen oxide (NOx) emissions because the formation of NOx depends on the oxygen concentration and the presence of LPG,leads to reduction of the oxygen concentration at the onset of NOx formation whichconsequently causes the NOx emissions to reduce.
Date of Award10 May 2019
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SupervisorPeilin Zhou (Supervisor) & Gerasimos Theotokatos (Supervisor)

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