M.Sc Thesis

M.Sc StudentCesana Or Felix
SubjectInternal Combustion Engine with Thermochemical
Recuperation Fed by Ethanol Steam Reforming
DepartmentDepartment of Mechanical Engineering
Supervisors ASSOCIATE PROF. Leonid Tartakovsky
Full Thesis textFull thesis text - English Version


The air pollution, climate changes and subsequent lack of energy sources became a major concern in this Century.

This study is focused on a development of an efficient propulsion system for vehicle and stationary applications. An internal combustion engine complemented with an onboard alcohol steam reforming system is examined, where the engine exhaust gases are used to sustain endothermic reactions of alcohol reforming. The study is focused on ethanol as a primary fuel.

The goal is to analyze the optimum working parameters of the Ethanol Steam Reformer and the Internal Combustion Engine system fueled by Ethanol as a primary fuel. The reformer and engine performance were simulated and analyzed using GT - Suite, ChemCAD and Matlab and the available literature data.

The schematic layout of a typical onboard alcohol steam reforming system is known and described in previous studies.

The research consists of three main stages.

(i) Engine performance Optimization. The engine performance was investigated for different types of fuel mixtures (compositions of ethanol reforming products). It was analyzed by the amount of engine emissions, specific fuel consumption and exhaust temperature. Every fuel mixture was characterized by: water to ethanol ratio (W/E) and the reforming temperature (Tref). The engine performance was analyzed for different values of: lambda (λ - air excess factor.) and the combustion start angle (θ0). The optimal engine working conditions (λ, θ0) were selected for every mixture. The optimization criteria: minimum engine emissions, minimum specific fuel consumption and maximum exhaust temperature.

(ii) Reformer - ICE (Internal Combustion Engine) System Optimization. The reformer and the ICE are considered as a "system". The purpose is to determine the optimal parameters of the whole system. Based on the results of stage one, engine performance with different compositions of ethanol reforming products was analyzed in order to find the optimal working conditions of the ICE-reformer system (defined by Tref, W/E, λ and θ0).

(iii) Reformer - heat exchanger design.

This study is based on a concept that can lead to development of a propulsion system that utilizes renewable energy sources, reducing the environmental pollution and improving energy efficiency through an efficient energy conversion process in ICE with thermo-chemical recuperation of the exhaust gas energy.

The analysis demonstrated the capability to sustain the required reactions in the reformer and to reform the liquid ethanol to hydrogen-rich gaseous fuel using a heat of the engine exhaust gases. The research identified the optimal system working conditions to get the best possible performance. The dimensions of the heat exchanger allow its mounting on board of a standard middle-size vehicle, even though there is a need for further investigation to get a more compact device. A comparison of the system performance versus gasoline and liquid ethanol didn’t show a considerable advantage of using ethanol as a fuel in ICE with thermo-chemical recuperation due to the high temperatures required to sustain the endothermic reactions of ethanol steam reforming. A preliminary analysis of ethanol after-burning in addition to the exhaust gases in order to sustain the appropriate reformer reactions was conducted.