Methanol vs. Gasoline as Internal Combustion Fuels in Drag Racing

Introduction

Claim

Methanol is the most efficient fuel.

Rationale

The claim that 'methanol is the most efficient fuel' is a highly debated topic in contemporary society. Scientists continually strive to develop new fuels with fewer negative impacts on both humanity and the natural environment. Fuels are compounds that store energy within chemical bonds, which is subsequently released during combustion (Encyclopedia, 2020). Furthermore, various fuels possess distinct chemical properties (Sarıkoç, 2020). Therefore, it is imperative to select an additional fuel, such as gasoline, for comparison to determine whether methanol truly stands out as the most efficient fuel.

From the initial claim and research ideas, the research question "Does the use of gasoline over methanol as an internal combustion fuel increase engine performance?" was formulated. However, the question was initially too broad, lacking specification regarding the context in which the fuel is being used. Subsequent research revealed that both methanol and gasoline are commonly used in drag racing. Moreover, the primary research question remained overly general concerning fuel efficiency.

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As previously mentioned, different fuels possess diverse properties, necessitating a comprehensive analysis of various components to establish their efficiency as fuels. Consequently, these ideas were integrated to form a secondary research question: "Does the use of gasoline over methanol as an internal combustion fuel in drag racing increase engine performance based on calorific value, latent heat of vaporization, and octane number?"

Drag racing is a form of motor racing in which automobiles, typically two at a time, compete to be the first to cross a predefined finish line (tutorialspoint, 2020).

A variety of fuels can be used in drag racing; however, methanol and gasoline are the most common choices.

Methanol, with the chemical formula CH₃OH, is the simplest alcohol. It consists of a methyl group linked to a hydroxyl group. Methanol is a lightweight, volatile, colorless, flammable liquid with a distinct alcoholic odor reminiscent of ethanol (ScienceDaily, 2020). It is also known as methyl alcohol and serves as a polar solvent. Due to its lower carbon content (CH₃OH), it readily undergoes combustion, producing carbon dioxide and water. The polar nature of methanol arises from the hydroxyl (OH) group, which induces a positive charge on the carbon and hydrogen atoms. Methanol exhibits hydrogen bonding, van der Waals forces of attraction, and dipole-dipole interactions.

In contrast, gasoline, commonly referred to as petrol, is a mixture of volatile, flammable liquid hydrocarbons derived from petroleum through fractional distillation (gasoline | Definition, 2020). The exact chemical composition of gasoline is undefined; however, most saturated gasoline molecules consist of a homogeneous mixture of small, relatively lightweight hydrocarbons containing between 4 to 12 carbon atoms. Gasoline is composed of paraffins (alkanes), olefins (alkenes), and cycloalkanes (gasoline | Definition, 2020).

As mentioned earlier, fuels release energy through combustion. Both methanol and gasoline undergo the process of combustion, resulting in the release of carbon dioxide and water, accompanied by the liberation of heat energy (exothermic reaction). The chemical reactions are as follows:

Methanol: 2CH₃OH + 3 O₂ → 2CO₂ + 4H₂O; (Merthe, 2018)

Gasoline: 2C₈H₁₈ + 25 O₂ → 16CO₂ + 18H₂O; (Amit, 2018)

Research Question

How does the use of gasoline over methanol as an internal combustion fuel in drag racing increase engine performance based on calorific value, latent heat of vaporization, and octane number?

Analysis and Interpretation

Efficiency in a fuel is characterized by numerous factors, but for drag racing fuels, three key attributes stand out: calorific value, latent heat of vaporization, and octane number. This research aims to compare these three critical characteristics between methanol and gasoline.

Calorific Value

The calorific value represents the total energy released as heat when a substance undergoes complete combustion with oxygen under standard conditions (Dictionary, 2020). Typically, this chemical reaction involves a hydrocarbon reacting with oxygen to produce carbon dioxide and water. Importantly, the calorific value of a liquid fuel is usually determined at a constant volume using a 'bomb calorimeter' (Calorimetry | lumen learning, 2020). These calorimeters are designed to be well-insulated to prevent heat loss to the external environment, ensuring the accurate measurement of heat produced during fuel combustion. The fuel sample is placed in a crucible inside the bomb calorimeter, which is then filled with oxygen at high pressure. Subsequently, the temperature increase resulting from the reaction is measured to calculate the energy generated. The calorific values of methanol and gasoline are presented in Table 1 below.

Table 1: The calorific value of methanol and gasoline.

According to Shabudeen (2014), a desirable fuel should possess a high calorific value, as it facilitates easy combustion within an internal combustion engine. As observed from Table 1, gasoline exhibits a significantly higher calorific value (45.8 MJ/Kg) compared to methanol (16.38 MJ/kg). This indicates that gasoline has a greater propensity for easy combustion, thereby substantially enhancing the engine performance of a drag racing car.

Latent Heat of Vaporization

The latent heat of vaporization is a physical property specific to a substance, defined as the heat required to convert one mole of liquid into vapor at its boiling point under standard atmospheric pressure (Wallace et al., 2006). This property is associated with the change in the state of a substance and is usually expressed in J/g. It can be determined using a calorimeter. After conducting extensive secondary research, an experiment outlined by Vytautas Kligys from Lehigh University was identified (Kligys, 1963) (Jessup, 1935). In this experiment, the fuel to be vaporized (gasoline and methanol) was contained within a 25 ml burette, and the calorimeter's temperature was measured using a platinum resistance thermometer. The Table 2 below presents the average latent heat of vaporization for methanol and gasoline.

Table 2: Latent Heat of Vaporization of methanol and gasoline.

As mentioned earlier, the latent heat of vaporization represents the amount of heat required to extract energy from a substance (Wallace et al., 2006). A lower value in this context enhances the efficiency and performance of an internal combustion engine by requiring less energy input to produce high energy output. The conducted experiments clearly demonstrate that methanol possesses a higher heat of vaporization (865.92 J/g) compared to gasoline (350 J/g). Consequently, gasoline can combust with lower energy input when contrasted with methanol, leading to a significant increase in engine performance.

Octane Number

The octane number serves as a standardized measure of engine performance, gauging a fuel's propensity to burn in a controlled manner rather than uncontrollably exploding (Platinum Iris, 2018). The fuel's tendency to auto-ignite is a critical characteristic that can influence an engine's ability to operate at its maximum thermodynamic potential. Rapid ignition after injection into the combustion chamber is desired in internal combustion engines, with high resistance to auto-ignition favored to prevent knocking. Knocking, an undesirable noise, results from the premature combustion of the compressed air-fuel mixture in the cylinder (Bhutia, 2015). Engine knocking can have catastrophic effects, acting as the primary limiting factor for thermodynamic efficiency. Iso-octane, a member of the octane family, serves as a reference standard to assess fuels' resistance to self-ignition (Speight, 2008). Test methods for determining the antiknock properties of fuels involve comparing them with blends of pure iso-octane hydrocarbons (2,2,4-trimethylpentane) (Speight, 2008). Therefore, a higher octane number indicates a fuel's greater capacity to withstand compression before detonation (ignition) (Platinum Iris, 2018).

Table 3: Octane number of methanol and gasoline.

Octane number provides valuable insights into the risk to engine longevity and performance when suboptimal fuels are used. For internal combustion engines, a high octane rating is crucial to mitigate engine knocking. Table 3, along with Appendix 2, demonstrates that methanol exhibits a slightly higher octane number (87.4) than gasoline (87). However, the difference between these values is not significantly substantial. Therefore, gasoline also possesses a favorable octane number, which is unlikely to have a profound negative impact on engine performance, rendering it a viable fuel choice for drag racing cars.

Conclusion and Evaluation

In this research investigation, three critical characteristics of drag racing fuels have been thoroughly examined, providing both qualitative and quantitative data from various research journals and websites. The characteristics of calorific value, latent heat of vaporization, and octane number were meticulously analyzed and compared between the two most commonly used drag racing fuels: gasoline and methanol.

By evaluating the three aforementioned characteristics, it was determined that gasoline stands out as a more efficient fuel for drag racing when compared to methanol. Gasoline boasts a higher calorific value, lower latent heat of vaporization, and a satisfactory octane number. While the evidence presented supports the superiority of gasoline over methanol, it is important to acknowledge certain limitations within the provided studies. These limitations include the reliability of the websites used to obtain calorific value and octane number data for gasoline, as they lack specification regarding the testing methods performed and have limited research citations. Additionally, this research investigation did not focus on a specific type of engine, such as V8 or V12, to conclusively establish gasoline's superiority as a fuel. Furthermore, to enhance the quality of this report, future studies could focus on specific engine types and analyze additional factors such as fixed carbon content, moisture content, air-fuel ratio, ignition temperature, and toxicity to comprehensively assess their impact on engine performance and efficiency.

Overall Results

The data gathered from various studies, journals, and websites aimed at determining the efficiency of gasoline versus methanol as a drag racing fuel leads to the conclusion that gasoline outperforms methanol. The analysis clearly demonstrates that gasoline produces a higher energy output with a lower energy input. Additionally, it enhances engine performance by reducing engine knocking, as indicated by its favorable octane number. Consequently, the review of studies conducted for the claim that "methanol is the most efficient fuel" is invalidated, as gasoline has been found to be the superior choice.

Reference List

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3. www.tutorialspoint.com. (2020). Drag Racing - Quick Guide - Tutorialspoint.
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5. Encyclopedia Britannica. (2020). Gasoline | Definition, Uses, & Facts.
6. Merthe, D. (2018). What is the equation for the combustion of methanol? - Quora.
7. Amit, R. (2018). What is the equation of combustion of gasoline? - Quora.
8. www.dictionary.com. (2020). Definition of calorific value | Dictionary.com.
9. Calorimetry | Chemistry for Majors. (2020). [online] Available at:
   https://courses.lumenlearning.com/chemistryformajors/chapter/calorimetry/#:~:text=A%2520calorimeter%2520is%2520a%2520device [Accessed 3 Aug. 2020].
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11. Acea.be. (2016). Differences Between Diesel And Petrol | ACEA - European Automobile Manufacturers' Association.
12. Shabudeen, S., 2014. FUELS AND COMBUSTION.
13. Wallace, J.M. and Hobbs, P.V. (2006). Heat of Vaporization - an overview | ScienceDirect Topics.
14. Kligys, V. (1963). Measurement of latent heat of vaporization at high pressure.
15. Jessup, R. (1935). HEATS OF VAPORIZATION OF GASOLINES.
16. Platinum Iris. (2018). ULP93 – Platinum Iris.
17. Bhutia, T.K. (2015). Knocking | internal-combustion engine | Britannica.
18. Speight, J.G. (2008). SYNTHETIC FUELS HANDBOOK Properties, Process, and Performance.
19. Naegeli, D., Yost, D., Moulton, D., Owens, E., & Chui, G. (1989). The Measurement of Octane Numbers for Methanol and Reference Fuels Blends.
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Appendices

Appendix 1

Calculation of Average Latent Heat of Vaporization:

Average latent heat of vaporization = sum of total values (cal/g) / no of experiments

= 6415.77 cal / 31 = 206.96 cal/g

= 206.96 cal/g = 865.92 J/g

Appendix 2

Calorific value of methanol and gasoline:

Heat of Vaporization (J/g):

Octane Number: