Date of Award

4-2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Mechanical Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Emad Elnajjar

Second Advisor

Salahaddin Al Omari

Third Advisor

Mohamed Selim

Abstract

Hydrogen is a clean and carbon free substitute with the ability to significantly cut down the harmful emissions while enhancing the energy efficiency of internal combustion engines (ICE) typically powered by conventional fossil fuels. Hydrogen is the most abundant elements which can be easily obtained from sources like water and biomass. The wide flammability range and high laminar flame velocity outstands hydrogen from other fuels. However, hydrogen fueled engines are more prone to abnormal combustion like knock and backfire due to its low ignition energy and high adiabatic flame temperature. To avoid backfire, several well developed approaches have been reported. Unlike backfire, combustion knock are more severe and difficult to control. Thus, a study on extending the hydrogen knock limit is of great importance. The main focus of this thesis is to investigate various strategies that helps in extending hydrogen fraction while avoiding the engine knock in spark ignition engine operating under hydrogen–gasoline dual fuel combustion where conventional gasoline is replaced drastically by hydrogen. The first part of the thesis investigates the hydrogen–gasoline combustion in a Ricardo single cylinder SI engine with hydrogen manifold induction and gasoline direct injection. A range of experimental trials were conducted to investigate the original knock limit, performance, combustion and emissions under various engine speed and gasoline injection quantity. Hydrogen exhibited superior results than pure gasoline which are more pronounced at low engine speed with the highest brake thermal efficiency of 27.48% at 1000 rpm. Apart from that, the highest gasoline injection quantity showed the least cyclic variation which is mainly due to the concentration of gasoline near the vicinity of spark plug. The result showed that at default configuration for the best combination (1000 rpm and 6 mg per cycle gasoline quantity) a hydrogen knock limit of 8 LPM was achieved. Next a comparison study between pure gasoline and hydrogen–gasoline mixture knock was conducted. The outcomes exhibited that the hydrogen enrichment results in severe knock. The combustion knock are usually inherited with high cylinder pressure and abnormal heat release rate. The heat release rate at knocking conditions were 151.2 and 128.53 J/deg for the 25% and 12.5% hydrogen flow rate compared to 86.86 J/deg for pure gasoline.

Following this, several methods that can be implemented to an existing engine on extending the hydrogen knock limit was investigated. To facilitate this studies, change in spark timing, intake air temperature and pressure, and dilution with CO2 gas and fuels possessing high latent heat of vaporization were adopted. A retardation in spark timing showed an increased hydrogen flow rate. The result showed that a hydrogen flow rate of 14 LPM was achieved from the original limit of 8 LPM when the spark timing retarded from 12° CA to 4° CA BTDC. This is due to the extension of combustion process to the expansion stroke with reduced the cylinder pressure and temperature. Moreover, a change in intake air pressure and temperature also facilitated the extension in hydrogen knock limit. An increase in intake air pressure and decrease in the intake air temperature allowed the extension of hydrogen knock limit. A hydrogen flow rate of 18 LPM was achieved at an intake air pressure of 112 kPa at 4° CA BTDC. Furthermore, hydrogen knock limit was influenced greatly by the addition of ethanol and methanol fuels. The highest hydrogen flow rate of 16 and 18 LPM was obtained for 50% volume proportions of ethanol and methanol, respectively. This increment was due to the high latent heat of vaporization of alcohol which provides a charge cooling effect during combustion. Apart from these strategies, dilution of combustible mixture with CO2 gas also extended the hydrogen knock limit. A maximum hydrogen flow rate of 16 LPM was achieved with 6 LPM CO2 dilution level, which can be attributed to the high heat capacity and inert nature of CO2 gas.

Further, the research outcomes can be extended to wide applications in the field of automotive and aerospace. These approaches can be implemented on jet, stationary and gas engines with less dependency on fossil fuel–based products.

Arabic Abstract


دراﺳﺔ ﺗﺠﺮﯾﺒﯿﺔ ﻹﺳﺘﺮاﺗﯿﺠﯿﺎت ﻣﺨﺘﻠﻔﺔ ﻟﺘﻤﺪﯾﺪ ﺣﺪود طﺮق اﻟﮭﯿﺪروﺟﯿﻦ ﻋﻠﻰ ﻣﺤﺮك إﺷﻌﺎل ﺷﺮارة ﺛﻨﺎﺋﻲ اﻟﻮﻗﻮد ﯾﻌﻤﻞ ﺑﺎﻟﮭﯿﺪروﺟﯿﻦ واﻟﺒﻨزﯾﻦ

ﯾﻌﺘﺒﺮ اﻟﮭﯿﺪروﺟﯿﻦ ﺑﺪﯾﻼً ﻧﻈﯿﻔًﺎ وﺧﺎﻟﯿًﺎ ﻣﻦ اﻟﻜﺮﺑﻮن، وله اﻟﻘﺪرة ﻋﻠﻰ ﺧﻔﺾ اﻻﻧﺒﻌﺎﺛﺎت اﻟﻀﺎرة ﺑﺸﻜﻞ ﻛﺒﯿﺮ ﻣﻊ ﺗﻌﺰﯾﺰ ﻛﻔﺎءة اﺳﺘﺨﺪام اﻟﻄﺎﻗﺔ ﻓﻲ ﻣﺤﺮﻛﺎت اﻻﺣﺘﺮاق اﻟﺪاﺧﻠﻲ اﻟﺘﻲ ﺗﻌﻤﻞ ﻋﺎدةً ﺑﺎﻟﻮﻗﻮد اﻷﺣﻔﻮري اﻟﺘﻘﻠﯿﺪي. اﻟﮭﯿﺪروﺟﯿﻦ ھﻮ اﻟﻌﻨﺎﺻﺮ اﻷﻛﺜﺮ وﻗﺮة واﻟﺘﻲ ﯾﻤﻜﻦ اﻟﺤﺼﻮل ﻋﻠﯿﮭﺎ ﺑﺴﮭﻮﻟﺔ ﻣﻦ ﻣﺼﺎدر ﻣﺜﻞ اﻟﻤﺎء واﻟﻜﺘﻠﺔ اﻟﺤﯿﻮﯾﺔ. إن ﻧﻄﺎق اﻟﻘﺎﺑﻠﯿﺔ ﻟﻼﺷﺘﻌﺎل اﻟﻮاﺳﻊ وﺳﺮﻋﺔ اﻟﻠﮭﺐ اﻟﺼﻔﺎﺋﯿﺔ اﻟﻌﺎﻟﯿﺔ ﯾﺘﻔﻮق ﻋﻠﻰ اﻟﮭﯿﺪروﺟﯿﻦ ﻣﻦ أﻧﻮاع اﻟﻮﻗﻮد اﻷﺧﺮى. وﻣﻊ ذﻟﻚ، ﻓﺈن اﻟﻤﺤﺮﻛﺎت اﻟﺘﻲ ﺗﻌﻤﻞ ﺑﻮﻗﻮد اﻟﮭﯿﺪروﺟﯿﻦ ﺗﻜﻮن أﻛﺜﺮ ﻋﺮﺿﺔ ﻟﻼﺣﺘﺮاق ﻏﯿﺮ اﻟﻄﺒﯿﻌﻲ ﻣﺜﻞ اﻟﻀﺮب واﻟﻨﺘﺎﺋﺞ اﻟﻌﻜﺴﯿﺔ ﺑﺴﺒﺐ طﺎﻗﺔ اﻻﺷﺘﻌﺎل اﻟﻤﻨﺨﻔﻀﺔ وارﺗﻔﺎع درﺟﺔ ﺣﺮارة اﻟﻠﮭﺐ اﻟﻤﻜﻈﻮﻣ ﺔ. ﻟﺘﺠﻨﺐ ﻧﺘﺎﺋﺞ ﻋﻜﺴﯿﺔ، ﺗﻢ اﻹﺑﻼغ ﻋﻦ اﻟﻌﺪﯾﺪ ﻣﻦ اﻷﺳﺎﻟﯿﺐ اﻟﻤﺘﻄﻮرة. ﻋﻠﻰ ﻋﻜﺲ اﻟﻨﺘﺎﺋﺞ اﻟﻌﻜﺴﯿﺔ، ﻓﺈن طﺮق اﻻﺣﺘﺮاق ﺗﻜﻮن أﻛﺜﺮ ﺧﻄﻮرة وﯾﺼﻌﺐ اﻟﺘﺤﻜﻢ ﻓﯿﮭﺎ. وﺑﺎﻟﺘﺎﻟﻲ، ﻓﺈن دراﺳﺔ ﺗﻤﺪﯾﺪ ﺣﺪ طﺮق اﻟﮭﯿﺪروﺟﯿﻦ ﻟﮭﺎ أھﻤﯿﺔ ﻛﺒﯿﺮة.

اﻟﺘﺮﻛﯿﺰ اﻟﺮﺋﯿﺴﻲ ﻟﮭﺬه اﻷطﺮوﺣﺔ ھﻮ دراﺳﺔ اﻻﺳﺘﺮاﺗﯿﺠﯿﺎت اﻟﻤﺨﺘﻠﻔﺔ اﻟﺘﻲ ﺗﺴﺎﻋﺪ ﻓﻲ زﯾﺎدة ﻧﺴﺒﺔ اﻟﮭﯿﺪروﺟﯿﻦ ﻣﻊ ﺗﺠﻨﺐ طﺮق اﻟﻤﺤﺮك ﻓﻲ ﻣﺤﺮك اﻹﺷﻌﺎل ﺑﺎﻟﺸﺮارة اﻟﺬي ﯾﻌﻤﻞ ﺗﺤﺖ اﺣﺘﺮاق اﻟﻮﻗﻮد اﻟﻤﺰدوج اﻟﮭﯿﺪروﺟﯿﻦ واﻟﺒﻨﺰﯾﻦ ﺣﯿﺚ ﯾﺘﻢ اﺳﺘﺒﺪال اﻟﺒﻨﺰﯾﻦ اﻟﺘﻘﻠﯿﺪي ﺑﺸﻜﻞ ﻛﺒﯿﺮ ﺑﺎﻟﮭﯿﺪروﺟﯿﻦ. اﻟﺠﺰء اﻷول ﻣﻦ اﻷطﺮوﺣﺔ ﯾﺒﺤﺚ ﻓﻲ اﺣﺘﺮاق اﻟﮭﯿﺪروﺟﯿﻦ واﻟﺒﻨﺰﯾﻦ ﻓﻲ ﻣﺤﺮك رﯾﻜﺎردو ذو اﻷﺳﻄﻮاﻧﺔ اﻟﻮاﺣﺪة ﺳﺒﺎرك ﺟﻨﺸﯿﻦ ﻣﻊ ﺗﺤﺮﯾﺾ ﻣﺸﻌﺐ اﻟﮭﯿﺪروﺟﯿﻦ وﺣﻘﻦ واﻟﺒﻨﺰﯾﻦ اﻟﻤﺒﺎﺷﺮ. ﺗﻢ إﺟﺮاء ﻣﺠﻤﻮﻋﺔ ﻣﻦ اﻟﺘﺠﺎرب اﻟﺘﺠﺮﯾﺒﯿﺔ ﻟﻠﺘﺤﻘﻖ ﻣﻦ ﺣﺪ اﻟﻀﺮب اﻷﺻﻠﻲ واﻷداء واﻻﺣﺘﺮاق واﻻﻧﺒﻌﺎﺛﺎت ﻓﻲ ظﻞ ﺳﺮﻋﺎت اﻟﻤﺤﺮك اﻟﻤﺨﺘﻠﻔﺔ وﻛﻤﯿﺔ ﺣﻘﻦ واﻟﺒﻨﺰﯾﻦ. أظﮭﺮ اﻟﮭﯿﺪروﺟﯿﻦ ﻧﺘﺎﺋﺞ أﻓﻀﻞ ﻣﻦ واﻟﺒﻨﺰﯾﻦ اﻟﻨﻘﻲ واﻟﺘﻲ ﺗﻜﻮن أﻛﺜﺮ وﺿﻮﺣًﺎ ﻋﻨﺪ ﺳﺮﻋﺔ اﻟﻤﺤﺮك اﻟﻤﻨﺨﻔﻀﺔ ﻣﻊ أﻋﻠﻰ ﻛﻔﺎءة ﺣﺮارﯾﺔ ﻟﻠﻔﺮاﻣﻞ ﺑﻨﺴﺒﺔ 27.48% ﻋﻨﺪ 1000 دورة ﻓﻲ اﻟﺪﻗﯿﻘﺔ. وﺑﺼﺮف اﻟﻨﻈﺮ ﻋﻦ ذﻟﻚ، ﻓﺈن أﻋﻠﻰ ﻛﻤﯿﺔ ﺣﻘﻦ اﻟﺒﻨﺰﯾﻦ أظﮭﺮت أﻗﻞ ﺗﻌﯿﺮ دوري واﻟﺬي ﯾﺮﺟﻊ ﺑﺸﻜﻞ رﺋﯿﺴﻲ إﻟﻰ ﺗﺮﻛﯿﺰ اﻟﺒﻨﺰﯾﻦ ﺑﺎﻟﻘﺮب ﻣﻦ ﺷﻤﻌﺔ اﻹﺷﻌﺎل. أظﮭﺮت اﻟﻨﺘﯿﺠﺔ أﻧﮫ ﻓﻲ اﻟﺘﻜﻮﯾﻦ اﻻﻓﺘﺮاﺿﻲ ﻷﻓﻀﻞ ﻣﺠﻤﻮﻋﺔ (1000 دورة ﻓﻲ اﻟﺪﻗﯿﻘﺔ و 6 ﻣﻠﺠﻢ ﻟﻜﻞ ﻛﻤﯿﺔ ﺑﻨﺰﯾﻦ ﻟﻜﻞ دورة) ﺗﻢ ﺗﺤﻘﯿﻖ ﺣﺪ طﺮق اﻟﮭﯿﺪروﺟﯿﻦ ﺑﻤﻘﺪار 8 ﻟﺘﺮ ﻓﻲ اﻟﺪﻗﯿﻘﺔ. ﺑﻌﺪ ذﻟﻚ أﺟﺮﯾﺖ دراﺳﺔ ﻣﻘﺎ رﻧﺔ ﺑﯿﻦ طﺮق اﻟﺒﻨﺰﯾﻦ اﻟﻨﻘﻲ وﺧﻠﯿﻂ اﻟﮭﯿﺪروﺟﯿﻦ ﯾﺆدي إﻟﻰ ﺿﺮﺑﺔ ﺷﺪﯾﺪ. ﻋﺎدةً ﻣﺎ ﺗﻜﻮن طﺮق اﻻﺣﺘﺮاق ﻣﻮروﺛﺔ ﻣﻊ ارﺗﻔﺎع ﺿﻌﺖ اﻷﺳﻄﻮاﻧﺔ وﻣﻌﺪل إطﻼق اﻟﺤﺮارة ﻋﯿﺮ اﻟﻄﺒﯿﻌﻲ ﻛﺎن ﻣﻌﺪل إطﻼق اﻟﺤﺮارة ﻋﻨﺪ ظﺮوف اﻟﻄﺮق 151.2 و 128.53 ﺟﻮل/درﺟﺔ ﻟﻤﻌﺪل ﺗﺪﻓﻖ اﻟﮭﯿﺪروﺟﯿﻦ 25% و 12.5% ﻣﻘﺎرﻧﺔ ب 86.86 ﺟﻮل/درﺟﺔ اﻟﺒﻨﺰﯾﻦ اﻟﻨﻔﯿﺰ.

ﺑﻌﺪ ذﻟﻚ، ﺗﻢ دراﺳﺔ اﻟﻌﺪﯾﺪ ﻣﻦ اﻟﻄﺮق اﻟﺘﻲ ﯾﻤﻜﻦ ﺗﻨﻔﯿﺬھﺎ ﻋﻠﻰ ﻣﺤﺮك ﻣﻮﺟﻮد ﻟﺘﻤﺪﯾﺪ ﺣﺪ طﺮق اﻟﮭﯿﺪروﺟﯿﻦ. ﻟﺘﺴﮭﯿﻞ ھﺬه اﻟﺪراﺳﺎت، ﺗﻢ اﻋﺘﻤﺎد اﻟﺘﻐﯿﯿﺮ ﻓﻲ ﺗﻮﻗﯿﺖ اﻟﺸﺮارة، ودرﺟﺔ ﺣﺮارة وﺿﻐﻂ اﻟﮭﻮاء اﻟﺪاﺧﻞ، واﻟﺘﺨﻔﯿﻒ ﺑﻐﺎز ﺛﺎﻧﻲ أﻛﺴﯿﺪ اﻟﻜﺮﺑﻮن واﻟﻮﻗﻮد اﻟﺬي ﯾﻤﺘﻠﻚ ﺣﺮارة ﺗﺒﺨﺮ ﻛﺎﻣﻨﺔ ﻋﺎﻟﯿﺔ. أظﮭﺮ اﻟﺘﺄﺧﺮ ﻓﻲ ﺗﻮﻗﯿﺖ اﻟﺸﺮارة زﯾﺎدة ﻓﻲ ﻣﻌﺪل ﺗﺪﻓﻖ اﻟﮭﯿﺪروﺟﯿﻦ. أظﮭﺮت اﻟﻨﺘﯿﺠﺔ أﻧﮫ ﺗﻢ ﺗﺤﻘﯿﻖ ﻣﻌﺪل ﺗﺪﻓﻖ ھﯿﺪروﺟﯿﻦ ﻗﺪره 14 ﻟﺘﺮ ﻓﻲ تدقيقه ﻣﻦ اﻟﺤﺪ اﻷﺻﻠﻲ اﻟﺒﺎﻟﻎ 8 ﻟﺘﺮ ﻓﻲ ﺗﺪﻗﯿﻘﮫ ﻋﻨﺪﻣﺎ ﺗﺄﺧﺮ ﺗﻮﻗﯿﺖ اﻟﺸﺮارة ﻣﻦ 12֯ زاوﯾﺔ اﻟﻜﺮﻧﻚ إﻟﻰ 4֯ زاوﯾﺔ اﻟﻜﺮﻧﻚ وﯾﺮﺟﻊ ذﻟﻚ إﻟﻰ اﻣﺘﺪاد ﻋﻤﻠﯿﺔ اﻻﺣﺘﺮاق إﻟﻰ ﺷﻮط اﻟﺘﻤﺪد ﻣﻊ اﻧﺨﻔﺎض ﺿﻐﻂ اﻷﺳﻄﻮاﻧﺔ ودرﺟﺔ ﺣﺮارﺗﮭﺎ. ﻋﻼوة ﻋﻠﻰ ذﻟﻚ، ﻓﺈن اﻟﺘﻐﯿﺮ ﻓﻲ ﺿﻐﻂ ھﻮاء اﻟﺴﺤﺐ ودرﺟﺔ اﻟﺤﺮارة ﺳﮭّﻞ أﯾﻀًﺎ زﯾﺎدة ﺣﺪ طﺮق اﻟﮭﯿﺪروﺟﯿﻦ. ﺳﻤﺤﺖ اﻟﺰﯾﺎدة ﻓﻲ ﺿﻐﻂ ھﻮاء اﻟﺴﺤﺐ ﺑﺘﻤﺪﯾﺪ ﺣﺪ طﺮق اﻟﮭﯿﺪروﺟﯿﻦ ﺑﻤﻘﺪار 18 ﻟﺘﺮ ﻓﻲ ﺗﺪﻗﯿﻘﮫ ﻋﻨﺪ ﺿﻐﻂ ھﻮاء ﻣﺪﺧﻞ ﻗﺪره 112 ﻛﺴﻠﻮ ﺑﺎﺳﻜﺎل ﻋﻨﺪ 4 درﺟﺎت زاوﯾﺔ اﻟﻜﺮﻧﻚ. ﻋﻼوة ﻋﻠﻰ ذﻟﻚ، ﺗﺄﺛﺮ ﺣﺪ طﺮق اﻟﮭﯿﺪروﺟﯿﻦ ﺑﺸﻜﻞ ﻛﺒﯿﺮ ﺑﺈﺿﺎﻓﺔ وﻗﻮد اﻹﯾﺜﺎﻧﻮل واﻟﻤﯿﺜﺎﻧﻮل. ﺗﻢ اﻟﺤﺼﻮل ﻋﻠﻰ أﻋﻠﻰ ﻣﻌﺪل ﻟﺘﺪﻓﻖ اﻟﮭﯿﺪروﺟﯿﻦ ﯾﺒﻠﻎ 16 و 18 ﻟﺘﺮ ﻓﻲ ﺗﺪﻗﯿﻘﮫ ﻟﻨﺴﺐ ﺣﺠﻤﯿﺔ ﺗﺒﻠﻎ 50% ﻣﻦ اﻹﯾﺜﺎﻧﻮل واﻟﻤﯿﺜﺎﻧﻮل، ﻋﻠﻰ اﻟﺘﻮاﻟﻲ. ﺗﺮﺟﻊ ھﺬه اﻟﺰﯾﺎدة إﻟﻰ اﻟﺤﺮارة اﻟﻜﺎﻣﻨﺔ اﻟﻌﺎﻟﯿﺔ ﻟﺘﺒﺨﯿﺮ اﻟﻜﺤﻮل واﻟﺘﻲ ﺗﻮﻓﺮ ﺗﺄﺛﯿﺮ ﺗﺒﺮﯾﺪ اﻟﺸﺤﻨﺔ أﺛﻨﺎء اﻻﺣﺘﺮاق. وﺑﺼﺮف اﻟﻨﻈﺮ ﻋﻦ ھﺬه اﻻﺳﺘﺮ اﺟﺘﯿﺎﺣﺎت، ﻓﺈن ﺗﺨﻔﯿﻒ اﻟﺨﻠﯿﻂ اﻟﻘﺎﺑﻞ ﻟﻼﺣﺘﺮاق ﺑﻐﺎز ﺛﺎﻧﻲ أﻛﺴﯿﺪ اﻟﻜﺮﺑﻮن أدى أﯾﻀًﺎ إﻟﻰ زﯾﺎدة ﺧﺬ طﺮق اﻟﮭﯿﺪروﺟﯿﻦ ﺑﻤﻘﺪار 16 ﻟﺘﺮ ﻓﻲ ﺗﺪﻗﯿﻘﮫ ﻣﻊ ﻣﺴﺘﻮى ﺗﺨﻔﯿﻒ ﺛﺎﻧﻲ أﻛﺴﯿﺪ اﻟﻜﺮﺑﻮن ﺑﻤﻘﺪار 6 ﻟﺘﺮ ﻓﻲ دقيقة، واﻟﺬي ﯾﻤﻜﻦ أن ﯾﻌﺰى إﻟﻰ اﻟﺴﻌﺔ اﻟﺤﺮارﯾﺔ اﻟﻌﺎﻟﯿﺔ واﻟﻄﺒﯿﻌﺔ اﻟﺨﺎﻣﻠﺔ ﻟﻐﺎز ﺛﺎﻧﻲ أﻛﺴﺪ اﻟﻜﺮﺑﻮن. ﻋﻼوة ﻋﻠﻰ ذﻟﻚ، ﯾﻤﻜﻦ ﺗﻮﺳﯿﻊ ﻧﺘﺎﺋﺞ اﻟﺒﺤﺚ ﻟﺘﺸﻤﻞ ﺗﻄﺒﯿﻘﺎت واﺳﻌﺔ ﻓﻲ ﻣﺠﺎل اﻟﺴﯿﺎرات واﻟﻔﻀﺎء. ﯾﻤﻜﻦ ﺗﻨﻔﯿﺬ ھﺬه اﻷﺳﺎﻟﯿﺐ ﻋﻠﻰ اﻟﻤﺤﺮﻛﺎت اﻟﻨﻔﺎﺛﺔ واﻟﺜﺎﺑﺘﺔ واﻟﻐﺎزﯾﺔ ﻣﻊ ﺗﻘﻠﯿﻞ اﻻﻋﺘﻤﺎد ﻋﻠﻰ اﻟﻤﻨﺘﺠﺎت اﻟﻤﻌﺘﻤﺪة ﻋﻠﻰ اﻟﻮﻗﻮد اﻷﺣﻔﻮري.

Download

Share

COinS