相同氧含量醇类混合燃料燃烧和排放特性差异研究

对一台4缸发动机燃用相同氧浓度的不同醇类混合燃料进行了试验研究,以对比不同三元燃料柴油机在相同转速不同负荷情况下的燃烧特性和常规排放的差异。试验结果表明:甲醇混合燃料在醇类混合燃料中获得最高的燃烧压力,而丁醇混合燃料的热释放率最高。与普通柴油相比,戊醇混合燃料在不同混合物中具有相对最佳的CO和未燃碳氢排放,甲醇混合燃料可获得最优的氮氧化物排放;乙醇混合燃料减小颗粒物效果明显,最大可以减少22.4%～55.6%的颗粒物数量浓度和3.4%～12.8%的颗粒物粒径,其中乙醇混合燃料的核态颗粒物和聚集态颗粒物排放量也最低,戊醇混合燃料达到最高(除高负荷外)。     

Emissions characteristics of spark ignition engine operating on lower–higher molecular mass alcohol blended gasoline fuels

An experimental investigation of emissions characteristics of lower–higher molecular mass alcohol blended gasoline fuels is presented in this paper. The alcohol component of the blends consisted of methanol, ethanol, propanol, butanol and pentanol. Apparatuses used in the present study were a single cylinder spark ignition engine, a hydraulic dynamometer and an exhaust analyzer. The variables that were continuously measured include engine rotational speed (min⁻¹), CO, CO₂, HC and NO emissions. During variable load tests, the results indicate that CO and HC levels in the engine exhaust are reduced with the operation on alcohol gasoline blends. NO emissions with alcohol gasoline blends are higher than with gasoline.     

Performance and emission analysis of compression ignition engine using biodiesels from Acid oil,Mahua oil,and Castor oil

Research on and use of biodiesels for engines is growing continuously in the present era. Compression ignition (CI) engine performance for biodiesels of blends B20 from Acid oil, Mahua oil, and Castor oil is experimentally investigated. The engine performance analysis in the form of brake‐specific fuel consumption, brake‐specific energy consumption, brake thermal efficiency (BTE), exhaust gas temperature (EGT), and air fuel ratio are compared with diesel as base fuel. Emission characteristics like CO, CO₂, NOx, and opacity are comparatively studied in detail for the considered biodiesels. The entire study is compared with the performance of engine when pure diesel is chosen as fuel. From the complete analysis it was observed that the BTE was higher for Acid oil and Mahua oil among the biodiesels used. And regarding CO emissions, Mahua oil showed lower effect than other biodiesels. Upto 6% increase in EGT of Mahua oil was obtained at no load and for other loads the percent reduced. For all the biodiesels the % enhancement in Co, CO₂, and NOx was more than 60% at highest load compared with diesel.     

Performance and emission analysis of cottonseed oil methyl ester in a diesel engine

In this study, performance and emissions of cottonseed oil methyl ester in a diesel engine was experimentally investigated. For the study, cottonseed oil methyl ester (CSOME) was added to diesel fuel, numbered D2, by volume of 5%(B5), 20%(B20), 50%(B50) and 75%(B75) as well as pure CSOME (B100). Fuels were tested in a single cylinder, direct injection, air cooled diesel engine. The effects of CSOME-diesel blends on engine performance and exhaust emissions were examined at various engine speeds and full loaded engine. The effect of B5, B20, B50, B75, B100 and D2 on the engine power, engine torque, bsfc's and exhaust gasses temperature were clarified by the performance tests. The influences of blends on CO, NO_x, SO₂ and smoke opacity were investigated by emission tests. The experimental results showed that the use of the lower blends (B5) slightly increases the engine torque at medium and higher speeds in compression ignition engines. However, there were no significant differences in performance values of B5, B20 and diesel fuel. Also with the increase of the biodiesel in blends, the exhaust emissions were reduced. The experimental results showed that the lower contents of CSOME in the blends can partially be substituted for the diesel fuel without any modifications in diesel engines.     

Direct injection diesel engine performance,emission, and combustion characteristics using diesel fuel,nonedible honne oil methyl ester,and blends with diesel fuel

Honne oil methyl ester (HOME) is produced from a nonedible vegetable oil, namely, honne oil, available abundantly in India. It has remained as an untapped new possible source of alternative fuel that can be used for diesel engines. The present research is aimed at investigating experimentally the performance, exhaust emission, and combustion characteristics of a direct injection diesel engine (single cylinder, water cooled) typically used in agricultural sector over the entire load range when fuelled with HOME and diesel fuel blends, HM20 (20% HOME + 80% diesel fuel)–HM100. The properties of these blends are found to be comparable with diesel fuel conforming to the American and European standards. The combustion parameters of HM20 are found to be slightly better than neat diesel (ND). For other blend ratios, these combustion parameters deviated compared with ND. The performance (brake thermal efficiency (BTE), brake‐specific fuel consumption, and exhaust gas temperature) of HM20 is better than ND. For other blend ratios, BTE is inferior compared with ND. The emissions (CO and SO) of HM20–HM100, throughout the entire load range, are dropped significantly compared with ND. Unburned hydrocarbon emissions of HM20–HM40, throughout the entire load range, is slightly decreased, whereas for other blend ratios, it is increased compared with ND. NO_x emissions of HM20, throughout the entire load range, is slightly increased, whereas for other blend ratios, it is slightly decreased. The reductions in exhaust emissions together with increase in BTE made the blend HM20 a suitable alternative fuel for diesel fuel and thus could help in controlling air pollution. Copyright © 2011 John Wiley & Sons, Ltd.     

Performance and emission characteristics of a diesel engine using isobutanol–diesel fuel blends

The aim of this study is to investigate the suitability of isobutanol–diesel fuel blends as an alternative fuel for the diesel engine, and experimentally determine their effects on the engine performance and exhaust emissions, namely break power, break specific fuel consumption (BSFC), break thermal efficiency (BTE) and emissions of CO, HC and NO_x. For this purpose, four different isobutanol–diesel fuel blends containing 5, 10, 15 and 20% isobutanol were prepared in volume basis and tested in a naturally aspirated four stroke direct injection diesel engine at full -load conditions at the speeds between 1200 and 2800 rpm with intervals of 200 rpm. The results obtained with the blends were compared to those with the diesel fuel as baseline. The test results indicate that the break power slightly decreases with the blends containing up to 10% isobutanol, whereas it significantly decreases with the blends containing 15 and 20% isobutanol. There is an increase in the BSFC in proportional to the isobutanol content in the blends. Although diesel fuel yields the highest BTE, the blend containing 10% isobutanol results in a slight improvement in BTE at high engine speeds. The results also reveal that, compared to diesel fuel, CO and NO_x emissions decrease with the use of the blends, while HC emissions increase considerably.     

Effect of injection timing on the exhaust emissions of a diesel engine using diesel–methanol blends

Environmental concerns and limited resource of petroleum fuels have caused interests in the development of alternative fuels for internal combustion (IC) engines. For diesel engines, alcohols are receiving increasing attention because they are oxygenated and renewable fuels. Therefore, in this study, the effect of injection timing on the exhaust emissions of a single cylinder, naturally aspirated, four-stroke, direct injection diesel engine has been experimentally investigated by using methanol-blended diesel fuel from 0% to 15% with an increment of 5%. The tests were conducted for three different injection timings (15°, 20° and 25 °CA BTDC) at four different engine loads (5 Nm, 10 Nm, 15 Nm, 20 Nm) at 2200 rpm. The experimental test results showed that Bsfc, NO_x and CO₂ emissions increased as BTE, smoke opacity, CO and UHC emissions decreased with increasing amount of methanol in the fuel mixture. When compared the results to those of original injection timing, NO_x and CO₂ emissions decreased, smoke opacity, UHC and CO emissions increased for the retarded injection timing (15 °CA BTDC). On the other hand, with the advanced injection timing (25 °CA BTDC), decreasing smoke opacity, UHC and CO emissions diminished, and NO_x and CO₂ emissions boosted at all test conditions. In terms of Bsfc and BTE, retarded and advanced injection timings gave negative results for all fuel blends in all engine loads.     

Performance,combustion and emission characteristics of a spark‐ignition engine with simultaneous injection of n‐butanol and gasoline in comparison to blended butanol and gasoline

Simultaneous injection of n‐butanol and gasoline through a new system of two injectors directing the sprays towards the back of the intake valve in a spark‐ignition engine was tried in lieu of injecting a blend of these fuels through a single injector. This system avoids the problem of phase separation, which is generally faced during the use of alcohol‐gasoline blends. Experiments were conducted on a spark‐ignition engine with this dual injection system using a fuel ratio of 1:1 (B50S) on the mass basis. High‐speed photographs indicated that the sprays from the injectors did not interfere till they reached the intake valve. Comparisons were made with pre‐blended butanol‐gasoline (B50) and neat (100%) gasoline at the best spark timing. All injection and spark parameters were controlled using a real time engine controller. Neat n‐butanol (B100) was superior only near full throttle with improved efficiency of the engine of about 1.2% (absolute). Heat release rates were observed to be higher and more advanced with B100 at wide open throttle. However, a reverse of this trend was observed at the throttle position of 15%. NO emission was also lower by 30% with B100 at wide open throttle as compared with gasoline. However, a small increase in carbon monoxide (CO) levels was observed because of lower post combustion temperatures as compared with gasoline and B50S. Simultaneous injection reduced hydrocarbon (HC) emissions by 13% to 50% as compared with B50 (blended fuel). HC emissions with gasoline and B50S were similar. Nitric oxide (NO) emission was lower with B50S as compared with gasoline; however it was higher than B50 because of better combustion. On the whole, the developed dual injection system was superior to the conventional method of blending in terms of performance, emissions and ability to change the fuel ratio as needed. B50S is suitable at all throttle positions, whereas B100 shows benefits at full throttle conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

Experimental investigations of performance,emission and combustion characteristics of Karanja oil blends fuelled DICI engine

Vegetables oils are simplest route of biofuel utilization in direct injection compression ignition (DICI) engines however several operational and durability problems are encountered while using straight vegetable oils in CI engines due to their high viscosity and low volatility. Reduction of viscosity by blending or exhaust gas heating leads to savings in chemical processing cost incurred on transesterification. In this experimental study, performance, emission and combustion characteristics of Karanja oil blends (K10, K20, K50 and K100) with mineral diesel were investigated in unheated conditions in a direct injection CI engine at different engine loads and constant engine speed (1500 rpm) vis-à-vis baseline data from mineral diesel. Analysis of performance parameters such as brake specific fuel consumption (BSFC), thermal efficiency, and exhaust gas temperature; mass emissions of various gaseous pollutant species; combustion parameters such as in-cylinder pressure rise, instantaneous heat release and cumulative heat release etc. were carried out. Detailed combustion analysis revealed that the combustion duration increased significantly even with smaller concentration of Karanja oil in the fuel blend. HC, CO and Smoke emissions were found to decrease for 20–50% (v/v) Karanja oil content in the fuel blends.     

Low-load hydrogen-diesel dual-fuel engine operation – A combustion efficiency improvement approach

Hydrogen-diesel dual-fuel operation can provide significant benefits to the performance and carbon-based emissions formation of compression-ignition engines. The wide flammability range of hydrogen allows engine operation at extremely low equivalence ratios while its high diffusivity and flame speed promote wide range combustion inside the cylinder. Nonetheless, despite the excellent properties of hydrogen for internal combustion, unburned hydrogen emissions and poor combustion efficiency have been previously observed at low-load conditions of compression ignition engines.The focus of the present study is to assess the effects of different engine operation and diesel injection parameters on the combustion efficiency of a heavy-duty dual-fuel engine while observing their interactions with the brake thermal efficiency (BTE) and emissions formation of the engine. In an attempt to reduce the unburned hydrogen rates at the exhaust of the engine, exhaust gas recirculation (EGR) and different diesel injection strategies were implemented. Statistical methods were applied in this study to reduce the experimental time.The results show a strong connection between unburned hydrogen rates, combustion and brake thermal efficiencies with the EGR rate. Higher EGR rates increase the intake charge temperature and provide improved hydrogen combustion and fuel economy. Operation of the dual-fuel engine at low-load with high EGR rate and slightly advanced main diesel injection can deliver simultaneous benefits to most of the harmful emissions and the BTE of the engine. Despite the efforts to achieve optimal engine operation at low loads, the combustion efficiency for most of the tested cases was in the range of 90%. Thus, increased hydrogen rates should be avoided as the benefits of the dual-fuel operation are weak at low-load conditions.     

Combustion characteristics of CI engine fueled with WCO biodiesel/diesel blends at different compression ratios and EGR

The present study investigated the effect of compression ratio (CR) with the use of exhaust gas recirculation (EGR) technology on the performance of combustion characteristics at different CRs and engine loads; the brake thermal efficiency (BTE), specific fuel consumption (SFC), volumetric efficiency (VOL.EFF), exhaust gas temperature, carbon dioxide emission (CO₂), hydrocarbons (HC), nitrogen oxides (NOx), and oxygen content (O₂). The single-cylinder, four-stroke compression ignition engine was run on a mixture of diesel and biodiesel prepared from Iraqi waste cooking oil at (B0, B10, B20, and B30). A comparison has been achieved for these combustion characteristics at different blends, load, and CRs (14.5, 15.5, and 16.5) at 1500 rpm constant engine speed. The transesterification process is used to produce biodiesel and ASTM standards have been used to determine the physical and chemical properties of biodiesel and compare them to net diesel fuel. The preliminary conducting tests indicated that engine performance and emissions improved with the B20 mixture. Experimental test results showed an increase in BTE when CR increased by 17% and SFC increased by 23%. It also found a higher VOL.EFF by 6% at higher pressure ratios. A continuous decrease in BTE values and an increase in SFC were sustained when the percentage of biodiesel in the mixture was increased. Emissions of carbon dioxide, HC, and NOx increased by 12%, 50%, and 40%, respectively, as CR reached high values. NOx increased with the addition of biodiesel to 35%, which necessitated the use of EGR technology at rates of 5% and 10%. The results indicated that the best results were obtained in the case of running the engine with a mixing ratio of B20 with the addition of 10% EGR, NOx decreased by 47% against a slight increase in other emissions.     

Experimental investigations of performance and emissions of Karanja oil and its blends in a single cylinder agricultural diesel engine

An experimental investigation has been carried out to analyze the performance and emission characteristics of a compression ignition engine fuelled with Karanja oil and its blends (10%, 20%, 50% and 75%) vis-a-vis mineral diesel. The effect of temperature on the viscosity of Karanja oil has also been investigated. Fuel preheating in the experiments – for reducing viscosity of Karanja oil and blends has been done by a specially designed heat exchanger, which utilizes waste heat from exhaust gases. A series of engine tests, with and without preheating/pre-conditioning have been conducted using each of the above fuel blends for comparative performance evaluation. The performance parameters evaluated include thermal efficiency, brake specific fuel consumption (BSFC), brake specific energy consumption (BSEC), and exhaust gas temperature whereas exhaust emissions include mass emissions of CO, HC, NO and smoke opacity. These parameters were evaluated in a single cylinder compression ignition engine typically used in agriculture sector of developing countries. The results of the experiment in each case were compared with baseline data of mineral diesel. Significant improvements have been observed in the performance parameters of the engine as well as exhaust emissions, when lower blends of Karanja oil were used with preheating and also without preheating. The gaseous emission of oxide of nitrogen from all blends with and with out preheating are lower than mineral diesel at all engine loads. Karanja oil blends with diesel (up to 50% v/v) without preheating as well as with preheating can replace diesel for operating the CI engines giving lower emissions and improved engine performance.     

Hydrogen addition to tea seed oil biodiesel: Performance and emission characteristics

Compression ignition engines are the dominant tools of the modern human life especially in the field of transportation. But, the increasing problematic issues such as decreasing reserves and environmental effects of diesel fuels which is the energy source of compression ignition engines forcing researchers to investigate alternative fuels for substitution or decreasing the dependency on fossil fuels. The mostly known alternative fuel is biodiesel fuel and many researchers are investigating the possible raw materials for biodiesel production. Also, hydrogen fuel is an alternative fuel which can be used in compression ignition engines for decreasing fuel consumption and hazardous exhaust emissions by enriching the fuel. In this study, influences of hydrogen enrichment to diesel and diesel tea seed oil biodiesel blends (B10 and B20) were investigated on an unmodified compression ignition engine experimentally. In consequence of the experiments, lower torque and higher brake specific fuel consumption data were measured when the engine was fuelled diesel biodiesel blends (B10 and B20) instead of diesel fuel. Also, diesel biodiesel blends increased CO₂ and NO_x emissions while decreasing the CO emissions. Hydrogen enrichment (5 l/m and 10 l/m) was improved the both torque and brake specific fuel consumption for all test fuels. Furthermore, hydrogen enrichment reduced CO and CO₂ emissions due to absence of carbon atoms in the chemical structure for all test fuels. Increasing flow rate of hydrogen fuel from 5 l/m to 10 l/m further improved performance measures and emitted harmful gases except NO_x. The most significant drawback of the hydrogen enrichment was the increased NO_x emissions.     

Study on combustion characteristics and particulate emissions of a common-rail diesel engine fueled with n-butanol and waste cooking oil blends

Biodiesel is a promising alternative fuel because of its renewability and extensive source of raw materials. Butanol can be blended in biodiesel to reduce the kinematic viscosity and promote the fuel atomization. In this respect, biodiesel was blended with 10% and 20% n-butanol, and the combustion characteristics and particulate emissions of the fuel blends were tested in a turbocharged, 6-cylinder, common rail diesel engine at a constant speed of 1400 rpm under seven engine loads. The experimental results show that under various engine loads, all of the butanol and biodiesel fuel blends provide faster combustion than diesel due to the higher oxygen content of n-butanol and the lower cetane number of butanol which results in stronger premixed combustion. The addition of butanol is beneficial to concentrating the heat release and thus shorten the combustion duration. With an increased proportion of butanol, soot emissions of butanol and biodiesel fuel blends decrease, the number concentration and volume concentration of ultrafine particles (UFPs) reduce noticeably. Meanwhile, the geometric mean diameters of UFPs decrease with an increase in butanol. With an increase of the engine loads, the number concentration peaks of UFPs gradually transfer from the size range of nucleation mode particles (NMPs) to the size range of accumulation mode particles (AMPs) due to the elevated combustion temperatures and high equivalence ratios. Moreover, biodiesel and fuel blends exhibit a higher percentage of NMPs as compared to diesel because of the fuel-bound oxygen, zero aromatics, and low sulfides.     

Effect of methanol fumigation on performance and emission characteristics in a waste cooking oil-fuelled single cylinder CI engine

Use of bio-oils in diesel engines results in increased NOx and smoke and reduced brake thermal efficiency. Dual-fuel engines can use a wide range of fuels mainly alcohols and yet operate with high thermal efficiency and simultaneous reduction of NO and smoke emissions. The present study aims to explore the effect of methanol–waste cooking oil (WCO) dual-fuel mode on performance and emission characteristics in a single cylinder Compression ignition (CI) engine producing 3.7 kW at 1,500 rpm. WCO was injected in the conventional injection system, replacing diesel as pilot fuel. Methanol was fumigated along with intake air using a variable jet carburetor, which was installed in the inlet manifold. The methanol was fumigated, and the energy share was varied for each load till the knock limit. Performance parameters like brake thermal efficiency (BTE) and emission parameters like HC, CO, NO, and smoke emissions were tested for various energy shares of methanol with WCO as a pilot fuel. The results show that an increase in methanol fumigation reduced BTE at lower loads. At 75% and 100% load conditions, BTE was higher with methanol addition. The maximum BTE was observed for 38% methanol share, which is about 11% higher, compared to WCO at 100% load condition. Methanol fumigation aided in the simultaneous reduction of NO and smoke emission, and the maximum reduction was occurred with 51% methanol share at 100% load condition. HC and CO emissions were higher at all load conditions with methanol fumigation.     

Performance,combustion and exhaust emissions characteristics investigation using Citrullus colocynthis L. biodiesel in DI diesel engine

The aims of this study is to investigate the performance, combustion and exhaust emissions of a single-cylinder, air cooled, direct injection (DI), compression ignition engine using biodiesel from non-edible feedstock. In this work, biodiesel (B100) used to lead this investigation is Citrullus colocynthis L. methyl ester (CCME) and its blends B30 with diesel fuel. The biodiesel is produced via alkaline-catalyzed transesterification process using methanol (6:1 M ratio), 1% of sodium hydroxide at the reaction temperature of 60 °C for 1 h. The important physical and chemical properties of CCME are close to those of diesel fuel. Fuels (diesel fuel, B100 and B30) were tested on a DI diesel engine at 1500 rpm for various power outputs. The results indicated that B100 and B30 exhibit the same combustion characteristics compared to diesel fuel. However, B100 and B30 display earlier start of combustion. At lower engine loads, the peaks of cylinder pressure and heat release rate (HRR) were higher for B30 than B100 and diesel fuel during premixed combustion period. At higher engine loads the peaks of cylinder pressure was higher for B100 than B30 and diesel fuel, but the HRR during diffusion combustion is more considerable than diesel fuel. The brake specific fuel consumption (BSFC) was higher for B100 than diesel fuel at all engine loads while B30 exhibited comparable trends. The thermal efficiency is slightly higher for B100 than B30 and diesel fuel at low loads and increase for B30 at full loads.B30 and B100 provided a higher reduction of hydrocarbons emissions up to 50% for B100. Nitrogen oxides and particulate matter emissions were also reduced.     

Comparative performance and emission studies when using olive oil as a fuel supplement in DI and IDI diesel engines

An experimental study is conducted to evaluate and compare the use of a diesel fuel supplement, specifically a 25/75% and a 50/50% blend of waste olive oil and commercial diesel fuel, in a four-stroke, DI (Direct Injection) diesel engine and in a four-stroke, IDI (Indirect Injection) diesel engine having a swirl-combustion chamber. The influence of the blends (diesel fuel+olive oil), for a large range of loads, has been examined on fuel consumption, maximum pressure, exhaust temperature, exhaust smokiness and exhaust-gas emissions such as nitrogen oxides (NO_x), hydrocarbons (HC) and carbon monoxide (CO). The differences in the measured performance and exhaust-emission parameters, from the baseline operation of either engine, are determined and compared. The study shows, for both the DI and IDI engines, a small penalty in specific fuel consumption, a moderate increase in exhaust smokiness and essentially unaltered maximum pressures and exhaust temperatures when using the blends. Also, for both the IDI and DI engines when using the blends, the study shows moderate decreases in emitted nitrogen oxides and increases in hydrocarbons as well as negligible increases in emitted carbon monoxide. Theoretical aspects of diesel engine combustion are used to aid the interpretation of the observed engines' behaviour.     

Experimental investigation on performance and emission characteristics of waste tire pyrolysis oil–diesel blends in a diesel engine

Disposal of waste tires is one of the most important problems that should be solved. This problem can be solved by considering waste tires for production of hydrogen or fuel for diesel engines. This paper presents the studies on the performance and emission characteristics of a four stroke, four cylinders, naturally aspirated, direct-injected diesel engine running with various blends of waste tire pyrolysis oil (WTPO) with diesel fuel. Fuel properties, engine performance, and exhaust emissions of WTPO and its blends were analyzed and compared with those of petroleum diesel fuel. The experimental results showed that WTPO–diesel blends indicated similar performance with diesel fuel in terms of torque and power output of the test engine. It was found that the blends of pyrolysis oil of waste tire WTPO10 can efficiently be used in diesel engines without any engine modifications.     

The effects of ethanol–unleaded gasoline blends on engine performance and exhaust emissions in a spark-ignition engine

Alcohols have been used as a fuel for engines since 19th century. Among the various alcohols, ethanol is known as the most suited renewable, bio-based and ecofriendly fuel for spark-ignition (SI) engines. The most attractive properties of ethanol as an SI engine fuel are that it can be produced from renewable energy sources such as sugar, cane, cassava, many types of waste biomass materials, corn and barley. In addition, ethanol has higher evaporation heat, octane number and flammability temperature therefore it has positive influence on engine performance and reduces exhaust emissions. In this study, the effects of unleaded gasoline (E0) and unleaded gasoline–ethanol blends (E50 and E85) on engine performance and pollutant emissions were investigated experimentally in a single cylinder four-stroke spark-ignition engine at two compression ratios (10:1 and 11:1). The engine speed was changed from 1500 to 5000 rpm at wide open throttle (WOT). The results of the engine test showed that ethanol addition to unleaded gasoline increase the engine torque, power and fuel consumption and reduce carbon monoxide (CO), nitrogen oxides (NO_x) and hydrocarbon (HC) emissions. It was also found that ethanol–gasoline blends allow increasing compression ratio (CR) without knock occurrence.     

Comparison and analysis of the emissions of a small non-road spark-ignition engine operating under different alcohol–gasoline blended fuels

In this experimental study we focused our interest on comparing the effect of lower and higher molecular mass alcohol–gasoline-blended fuels on the regulated emissions emitted by a small non-road spark-ignition engine. Twenty-one test fuels were used in this experimental study that included gasoline as a reference as well as low and high molecular mass alcohol–gasoline blends containing 5%, 10%, 20% and 40% v/v. In exhaust gases that originated from alcohol gasoline test fuels, low CO/HC and high CO₂/NO_x emissions were observed as the total percentage of alcohol in the blend increased. Methanol–gasoline blends seemed to achieve good combustion efficiency, but the engine will require a catalytic converter against high NO_x emissions. Butanol–gasoline blends in several cases gave lower emissions in comparison with the ethanol and propanol–gasoline blends. Finally, the pentanol–gasoline blends showed exactly the same emission patterns as those of neat gasoline.