Researching Engine Cycles and Building a Steam Engine
Xander Stabile Dr. Dann ASR A Block 1 May, 2020
Abstract: The ultimate goal of this project is to design and build a steam engine, with the goal of learning about various engine cycles while building essential mechanical skills. A dual piston steam engine was manufactured using machined brass parts: two brass pistons, a cylinder assembly, and a crankshaft. The crankshaft is fixed horizontally between two wooden vertical mounts on a wooden base, and the cylinder assembly is fixed to the same wooden base with its own separate wooden stand. With the crankshaft achieving a max rotational speed of around 957 RPM, this engine could be implemented into medium sized toys or light-duty machinery.
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I. Big Idea In my second semester ASR independent research project I will be building a steam engine, following many different prototypes and extensive research into engine cycles of both gasoline engines and Stirling engines. After making the prototype engines, I will build the final steam engine by implementing the effective methods I will learn from building the various prototypes. Simultaneously, I will learn how both steam engines and gas engines work, as well as their uses in the world today, their differences, and their similarities and differences in their ideal engine pressure/volume cycles. I will be pursuing engineering in college, most likely a major that heavily involves mechanical engineering. Biomedical engineering/Biomechanics, which is my current planned major, involves mechanical systems in biological contexts. So, for my second semester ASR research project, I knew that I wanted to pursue a project that was heavily mechanical, and could even allow me to begin to explore machining parts to create a final product. The other half of my inspiration for this project was my love for cars. I initially wanted to build a V8 gasoline engine, which I would then be able to install in my car. However, I had a few worries about this; not only was I worried I would destroy my beloved car should something go wrong, but, more importantly, I did not have the machine precision for that project to be plausible. I then reached the conclusion of building a steam engine for my second semester ASR project. Building a steam engine would task me with a mechanical challenge, one that would require me to become comfortable with new machines, tools, materials, and concepts. I know I will continue using all of these methods, machines, and materials in my college career and beyond, so I am excited for the opportunity to pursue a project that will expose me to all of them.
II. Introduction One of the most pressing issues of today, one of the most debated topics of 2020, is climate change. According to NASA, the world will change drastically before the decade is over; there will be no ice remaining in the Arctic, sea levels will rise a few feet, natural disasters will be stronger and occur more frequently, and temperatures will continue their increasing trend.1 These effects can be attributed to the increasing amount of greenhouse gasses in the Earth’s atmosphere, gasses that absorb and trap heat inside of Earth’s atmosphere. The United States Environmental Protection Agency attributes 22% of all greenhouse gas emissions to industry emissions, as shown in a graph by the Environmental Protection Agency below. Industry emissions are the result of burning fossil fuels as a method of generating energy.2
1 “The Effects of Climate Change.” NASA, NASA. 2 “Sources of Greenhouse Gas Emissions.” EPA, Environmental Protection Agency. Stabile 2
Diagram 1: Diagram 1 shows the percentage of gas emissions each economic sector contributed in 2017. Data and graph provided by the Environmental Protection Agency. However, nuclear power is a source of energy and is an alternative source of energy that has proven to be more beneficial to the environment. Nuclear power is a very efficient source of power, and avoids the byproduct of emitting tons of carbon dioxide and greenhouse gasses. Currently, there are 450 nuclear reactors around the world, generating approximately 10% of the world’s energy. However, this number is on the rise.3 Nuclear power plants generate energy by boiling water into steam, using the heat energy released during a process called nuclear fission, where the nucleus of a large atom is split. Nuclear power plants split uranium atoms by colliding them with neutrons at high speeds, causing an enormous release of heat energy as the uranium atom splits. The equation for the nuclear fission of uranium is shown below:
high − energy neutron + U 235 → U 236 → Kr92 + Ba141 This heat energy is then harnessed and used to boil water into steam, where the steam then turns a turbine that activates generators to create electricity.4 In the spirit of saving the world from the jaws of climate change, nuclear power plants may become a leading source of energy in the future. Steam is the element that turns the turbine in the nuclear power plant, much like the steam in a steam engine turns a flywheel. Steam engines may be the key to the future, and could be essential in combating climate change. Therefore, it is paramount that they are understood, so that we can be most efficient with converting the heat energy of the nuclear reaction into usable, clean energy. Steam engines have a long and extensive history. Steam engines were first invented and used by a man named Thomas Newcomen, who built the steam engines to help pump water out of mines. However, these first steam engines were wildly inefficient; the metal was to be cooled and reheated multiple times, which wasted energy and eventually warped and ruined the material. As a result, James Watt invented a steam engine with a separate condenser in 1765, a
3 “Nuclear Power Is Essential for Energy, Environment, & the Economy.” World Nuclear Association, World Nuclear Association. 4 “U.S. Energy Information Administration - EIA - Independent Statistics and Analysis.” Nuclear Power Plants - U.S. Energy Information Administration (EIA). Stabile 3 solution that allowed the metal to be hot the entire time. This engine relied on pressure to push the piston down, where the steam would then be able to flow into the condenser by a series of valves. This new model allowed water to be pumped from wells and mines much more efficiently, which inspired the engine to be applied to other industries to power miscellaneous machines.5 Diagram 2 shows the Watt steam engine.
Diagram 2: Diagram 1 shows the Watt steam engine. As the piston reaches its top position, the chamber’s inlet steam valve closes and the valve to the condenser opens. The condenser, which is of lower temperature and thus lower pressure, acts as a vacuum. The air flows to the condenser and condenses to water, which is expelled from the engine. The valve connecting the chamber to the condenser closes, and the lack of pressure in the chamber, the atmospheric pressure pushing down on the piston, and gravity all push the piston back down, where the steam inlet valve reopens.6 As steam engines evolved, they eventually powered steamboats, locomotives, and even automobiles. Though these engines were later overpowered by gasoline engines, steam engines may begin to rise again in popularity as the threat of irreversible climate change looms closer.
III. Design Components: Cylinder Assembly: The cylinder assembly consists of two cylinders, an air inlet tube, and an endcap. The large cylinder is fitted with an endcap so as to not let any air escape; the pressure in the large cylinder is the driving force of the engine, so it is essential for the large cylinder to be airtight. The small cylinder does not have an endcap, allowing the air to escape during a certain phase of the cycle by means of the air slit in the small piston. The two cylinders are connected (by a combination of solder and heat-resistant epoxy to ensure a strong, airtight connection) together side-by-side, with a hole drilled through both sides of the small cylinder and the connecting wall of the large cylinder to allow pressurized air to flow through. The air inlet tube feeds the air
5 “Brief History of the Steam Engine.” Steam Engine History. 6 “Watt Steam Engine.” Wikipedia. Stabile 4 directly into the hole connecting to the small piston. The entire cylinder assembly is made from 360 alloy brass. This alloy is especially machinable, while also able to tolerate high pressures and temperatures. The cylinders rest on a block attached to the base. Small Piston: The small piston rests in the small cylinder of the cylinder assembly, airtight yet able to slide inside of the cylinder. The small cylinder is designed not to push the crankshaft, but to control the airflow to and from the large cylinder chamber during certain phases of the cycle as the large piston turns the crankshaft. When the engine is in the first phase of its cycle (see below), the hole through the small piston directly aligns with the hole through the cylinder assembly, allowing the pressurized air to flow through the air inlet tube and into the large cylinder chamber, starting the “combustion” phase of the large piston. When the crankshaft rotates 180º, the piston moves (pulled forward) where the air slit in the side of the piston facing the large cylinder allows air to escape out of the hole connecting the large and small cylinders, through the air slit, and out the bottom of the small cylinder. The small piston is also made out of 360 alloy brass for its machinability and tolerance to high heat and pressure. Large Piston: The large piston rests in the large cylinder of the cylinder assembly, airtight yet able to slide inside of the cylinder. The large piston is designed to apply a torque to the crankshaft. When air is able to flow through the small piston and the holes connecting the cylinders, the pressure from the air pushes the piston out, which turns the crankshaft. As the air from the large cylinder chamber escapes through the air slit in the small piston, the rotation of the crankshaft pushes the large piston back to the starting position. Connecting Rods: The connecting rods simply connect the pistons to the crankshaft. The rods were bought on Amazon for their adjustability; the ends can screw in/out a little to adjust the length of the connecting rod, if needed. Their sole purpose is to push the crankshaft or pull the piston, depending on the phase of the cycle of rotation. Crankshaft: The crankshaft is also made of 360 alloy brass; this specific alloy of brass is very machinable yet also durable and strong. The crankshaft is held by both ends by ball bearings connected to the base. The flywheel is fit with epoxy on one of the sections of the crankshaft, with a raised ridge to help keep it in place. The cranks are connecting rods between the sections of the crankshaft, and they run through the holes at the ends of the connecting rods. The crank furthest from the flywheel is attached to the large piston, the crank closer to the flywheel is attached to the small piston. The large piston crank has a longer moment arm than the small piston crank, allowing the large piston to exert a large torque on the crankshaft during its “combustion phase”. Flywheel: The flywheel is a simple ball bearing, fit with epoxy over the crankshaft. The ball bearing has been seized up with epoxy. The ball bearing was chosen for its weight and dimensions for its weight; making one with the lathe is possible, but would have been much more expensive. Base: The base is a simple, wooden, laser-cut square. There are three blocks raised from the base: one holding the cylinder assembly, and two on either side of the crankshaft holding the bearings that lock it in place. Stabile 5
Cycle: Below is a set of diagrams showing the cross sectional area of the crankshaft. The cylinder assembly and pistons would be on the left side. The red shows the crank connecting to the large piston, while the blue shows the crank connecting to the small piston.
Phase 1 Phase 2 Phase 3 Phase 4 Phase 1: The small and large pistons are in their “starting positions”, meaning the hole in the small piston does not align with the hole in the cylinder assembly, preventing the air from flowing from the air inlet tube into the large cylinder. The flywheel continues to turn from the previous cycle, or, if the engine is starting, an outside source gives the flywheel the starting push. Phase 2: The small piston is pushed in (pushed backwards) as the crankshaft turns, allowing the air to flow from the inlet tube, through the hole in the small piston, and into the large cylinder. The pressure forces the large piston up, and the large piston pushes out, applying a torque on the crankshaft. Phase 3: The small piston is pulled out (pulled forward) as the large piston continues to push the crankshaft, moving the hole in the small piston away from the air inlet tube, preventing air flow to the large cylinder. The momentum of the flywheel carries the large piston to its maximum position, continuing to pull the small piston out as well. Phase 4: The small piston is pulled out, where the groove in the small piston lines up with the hole connecting the large cylinder to the small cylinder. The pressurized air escapes the system through the groove in the small piston, depressurizing the large cylinder chamber. The momentum of the flywheel pushes the large piston and small piston back in, back to their “starting positions” in Phase 1. Reference: This figure shows the cylinder assembly and pistons through all four phases, starting with Phase 1 on the left and Phase 4 on the right. The arrows through the cylinder assembly represent the air flow, while the arrows on the piston represent the movement of the piston during the 90º rotation from the prior Phase.
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CAD Drawings: Cylinder Assembly:
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Small Piston:
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Large Piston:
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Crankshaft:
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Pictures of Assembly:
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IV. Theory The underlying premise of the operation of a steam engine is the expansion of air due to heat. When heat is applied to a closed cylinder of air, the kinetic energy of each individual air molecule increases. The first step to the operation of a steam engine is boiling water. When heat is applied, the increase in kinetic energy of the water molecules cause them to begin to vibrate. At a certain temperature, these vibrations become violent enough that the molecular bonds between molecules break, and the water boils into steam, and the molecules are free to move around the space. As heat energy continues to be applied, the energy is transferred to the kinetic energy of the molecules, increasing the speed of the molecules. The molecules closest to the heat source increase in kinetic energy first, then transfer kinetic energy to other molecules through collisions. In a steam engine, steam is able to do work in the system by moving the piston due to high pressure inside of the cylinder. As the excited water molecules move around the cylinder, they collide with the walls of the cylinder, exerting an impulse force on the walls of the container. The more kinetic energy that the molecules have, the more force they will exert as they collide with the cylinder walls. The accumulative force of the molecules per unit surface area of the cylinder is the pressure of the steam inside of the cylinder. As heat energy continues to be applied to the system, eventually the cylinder becomes pressurized to the point that the molecules exert adequate force on the walls of the cylinder, moving the piston. This process can be explained by the ideal gas law, using the equation PV=nRT. In this equation, R is a constant. Therefore, the variables in this scenario that would fluctuate would be the pressure (P), volume (V), temperature (T), and the number of moles of ideal gas (n). An ideal gas is a system in which molecules in a gaseous state elastically collide with each other, and there are no intermolecular attractive forces due to the partial charges on the molecules. In a steam engine, as gas would rise from the heat source, the number of moles of molecules present would increase. Alternatively, if a displacer cylinder is used, or if there is a second cylinder in the system, gas may flow between chambers, which would decrease the number of moles of molecules in the chamber which the gas is flowing from. If the volume and temperature of the system remains constant, this would increase the pressure of the gas inside of the cylinder. Assuming that the number of molecules in the cylinder remains constant, as heat energy is added to the system, the temperature of the system would increase. This would cause an increase in pressure, as the molecules do not initially have enough kinetic energy to exert enough force to increase the volume of the system. However, as more heat energy is added, the pressure becomes so great that the piston is moved, increasing the volume of the system. The pressure would drop with this increase in volume, according to the ideal gas law.7 For example, if there is an original atmospheric pressure in the chamber of a cylinder with a piston attached at a specific temperature and volume, then there are a certain number of molecules in the chamber. If the number of molecules doubles while the volume and temperature remain constant, the ideal gas law demonstrates that the pressure inside the chamber would double. The increased pressure would push out against the piston with a greater force per area than the force pushing in due to atmospheric pressure. The net force outward would cause the piston to move, changing the volume. Assuming the number of molecules and temperature are
7 “Ideal Gas Law.” Ideal Gas Law. Stabile 14 constant, the volume would double until the pressure inside the chamber would return to atmospheric pressure, where the piston would remain at rest. In a steam engine, as the piston moves, either a displacer cylinder or a condenser chamber would be used. As the displacer cylinder pushes the air molecules away from the piston, or as the molecules flow away from the piston into the condenser chamber, the pressure would decrease and the piston would push back in, decreasing the volume and pressure (as a result of the decrease in the number of moles of the volume). The cycle would then start again, as all components of the system are reset to their original positions. An example of this cycle is the Watt steam engine, as previously shown in Diagram 2 above. In my steam engine, the air would escape the large cylinder during Phase 3 and Phase 4 of the crankshaft rotation, returning the pressure inside the large cylinder to return to atmospheric pressure, bringing the piston back to its original position. The Carnot cycle is the ideal cycle for a gasoline engine, meaning that it is a cycle of maximum efficiency allowed by physical laws in terms of the amount of applied heat energy that can be used for work. Graph 1 shows the Carnot cycle:
Graph 1: Graph 1 depicts the Carnot cycle, the ideal engine cycle allowed by physical laws. The x-axis is Volume, the y-axis is Pressure.8 The Carnot cycle consists of two isothermal processes and two adiabatic processes. Isothermal processes allow for expansion or compression, changing to volume and pressure of a chamber, without a change in temperature. Adiabatic processes allow for a change in pressure and volume, however no heat energy is lost or added to the system. This cycle is most efficient because it allows for the most work to be done by the engine for the amount of heat energy put into the system. The Carnot efficiency is equal to the T H −T C × 100%. However, these processes T H are a result of very slow changes in volume and pressure, and, with the speed required in all machines today, are simply not plausible in an effective engine in today’s world.9
8 “The Efficiency of the Carnot Cycle.” ResearchGate. 9 “Carnot Cycle.” Carnot Cycle. Stabile 15
The Carnot cycle is when an engine undergoes isothermal expansion (between 1 and 2), adiabatic expansion (2-3), isothermal compression (3-4), and adiabatic compression (4-1). Starting from 1, to undergo adiabatic expansion, the piston must move to slowly expand the volume inside the chamber without the temperature changing inside the chamber. In order for this to occur, a large, hot reservoir must keep the temperature perfectly constant as the piston moves. During the adiabatic expansion, the piston must move to continue to increase the volume, however, the walls of the cylinder must be insulated to ensure that no heat energy is gained or lost during the expansion. During isothermal compression, the piston must now start to decrease the volume inside the chamber, however the temperature must be maintained by a large, cold reservoir. Finally, once again, the cylinder must be insulated during adiabatic compression so no heat energy is lost or gained as the piston moves back to its starting point. Different points of the cycle have many different requirements in order for the engine to reach Carnot efficiency, however these various parameters are not plausible in the real world. Also, as stated above, the piston would have to move very slowly in order for this to happen, which is also not practical in the machines of the world today. The Stirling engine is a type of steam engine, one that utilizes a displacer cylinder. The cylinder and piston is sealed, meaning that no air comes in or out of the system, unlike modern gasoline engines; the moles of molecules inside of a Stirling engine cylinder is constant. As a result, the efficiency cycle for a Stirling engine, called the Stirling cycle, is different from the Carnot cycle. Graph 2 depicts the Stirling cycle:
Graph 2: Graph 2 depicts the Stirling cycle.10 The Stirling cycle reaches the same thermal efficiencies that the Carnot engine does. Due to its modified shape and seeing as the air inside a Stirling engine is sealed while new air is cycled into gasoline engines, the Stirling cycle achieves the same thermal efficiency as the Carnot cycle, T theoretically, with the Stirling efficiency equal to 1 − L . However, in actuality, this is much T H harder to achieve than gasoline engines. The Stirling cycle requires a tremendous amount of pressure, which is not plausible in terms of sealing in a Stirling engine. The temperature difference between the hot and cold sides of the cylinder must be large, however, this causes
10 “Stirling Cycle.” Simon Fraser University. Stabile 16 stresses on the cylinder material. Finally, most engines today require quick shifts between multiple power output gears; Stirling engines only have one setting.11 The Stirling cycle requires a Stirling engine to undergo isothermal expansion (1-2), isometric heat removal (2-3), isothermal compression (3-4), and isometric heat addition (4-1). During the isothermal processes, heat energy is added (1-2) or removed (3-4) from the system, however the temperature of the system does not change, which makes the expansion/compression a long process. During the isometric processes, the internal energy of the system changes; however, seeing as the air in Stirling engines are recycled, this process takes an extremely long time. This entire cycle takes a very long time to complete with perfect theoretical efficiency, which, again, simply is not practical in today’s world.
V. Results Measuring Rotational Speed: A digital tachometer was used to measure the rotational speed of the crankshaft. The flywheel outside of the flywheel was covered with non-reflective electrical tape. Then, one small strip of special reflected tape was placed on top of the electrical tape. As the flywheel rotated when the engine was operating, the tape would indicate a full rotation. The digital tachometer emits a laser, and has a sensor built in behind the laser to detect the light when it bounces back from a surface. When the sensor registers the reflected laser after it bounces off the reflective tape on the flywheel, the time between sensor triggers helps calculate the rotational speed of the flywheel. Another way to measure rotational speed is to use a magnet, a hall chip, and an oscilloscope. A small magnet is attached to the flywheel. When the hall chip is held near the flywheel, the oscilloscope will measure the frequency of the cycle. Then, to convert the frequency measured by the oscilloscope to a rotational speed in RPM, the following equation is sec used: ω = f × 60 min . Measuring Air Pressure: Using an air compressor with an attached gauge (0psi-15psi), the inlet air pressure into the steam engine can be measured. When the engine is running, the gauge will fluctuate due to the different cycles of the steam engine, where the inlet air is blocked by the small piston during some stages of the cycle and flows through the hole in the small piston during other stages, causing a fluctuation in air pressure reading. To determine the air pressure measurement, the average value of the fluctuating needle on the air pressure gauge is read and measured.
11 “Stirling Cycle.” Simon Fraser University. Stabile 17
Rotational Speed as a Function of Input Air Pressure
Table 1: Rotational Speed versus Air Pressure
Air Pressure (psi) Average Rotational Speed (RPM) 4 220.3 5 300.3 6 376.0 7 414.7 8 450.3 9 490.7 10 548.3 11 586.0 12 629.0 13 651.3 14 757.3 15 774.0 Table 1: Table 1 shows the data from the measurements of the experiment of rotational speed versus air pressure. For more accurate results, three trials of rotational speed were measured for each air pressure, and the average rotational speed was measured for each air pressure value.
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Graph 3: Graph 3 shows the graph of Average Rotational Speed vs. Air Pressure Measuring Minimum and Maximum Rotational Speed: The steam engine operates similar to a gasoline engine; it needs a starting push before the engine can operate on its own. To measure minimum rotational speed, the engine first has to be rotating, then the input air pressure is slowly turned down until the engine is barely sustaining rotation before the rotational speed is measured. To test the maximum rotational speed, the air pressure could be gradually increased until the engine either breaks or the rotational speed no longer speeds up as the input air pressure is increased. For the sake of safety for both the steam engine and human life, the engine was not pushed to its breaking point. Instead, the maximum rotational speed listed is the highest rotational speed measured during normal testing. While the engine could probably achieve higher speeds, the engine was not pushed for fear of it breaking.
Table 2: Specifications of the Steam Engine
Minimum Rotational Speed (RPM) 194.7
Maximum Rotational Speed Tested (RPM) 957
Table 2: Table 2 displays the specifications of the speed engine, showing the minimum rotational speed and the maximum tested rotational speed Measuring Torque: For this steam engine, is it difficult to measure the torque of the steam engine due to the design for how it works. The steam engine works in phases, where force is only exerted on the crankshaft during a fraction of each rotation. Therefore, it is difficult to measure both the running and starting torque of the steam engine. However, it is possible to calculate the torque of the steam engine, using the area of the base of the large piston ( in2 ), the input air pressure ( psi ), and the length of the moment arm of the crankshaft ( m ). The equation to calculate the torque of the steam engine at a point in its rotation is as follows: 1 P ascal τ = P airApistonl × .00015 psi
Line of Best Fit of Graph 3: Rotational Speed as a Function of Input Air Pressure
y = 47.7867x + 62.5429
VI. Conclusion In this research project, a steam engine was machined and assembled, including two pistons, a cylinder assembly, and a crankshaft. The parts were machined using a lathe, then detailed and modified using a milling machine. In the end, the steam engine operated quite smoothly, achieving rotational speeds from as low as 194.7 RPM to as high as 957 RPM, without failure or any sign of wear to the various parts. While this machine has potential to push the Stabile 19 crankshaft faster than 957 RPM, due to caution for safety for both the machine and human operators, the steam engine was not pushed much past this limit. In this range of rotational speeds, the engine operated exactly as expected; as shown in Graph 3 in the Results section of this research paper, as the inlet air pressure was increased, the rotational speed of the crankshaft increased linearly. The equation of the line of best fit as shown in Graph 3 explains how with every increase of 1 psi, the RPM of the steam engine increases by approximately 47.8 RPM. During the experimentation process, there is some error in precision in reading the correct pressure values from the gauge on the air compressor. Due to the different stages of the cycle, in which the small piston blocks the inlet air from entering the steam engine during some stages and allows the air through during other stages, the gauge on the air compressor fluctuates as the engine is working. Therefore, the average air pressure reading of the fluctuating needle is measured on the air pressure gauge. However, this allows for some error, especially as the air pressure is increased, seeing as the gauge needle fluctuation increases as the air pressure increases. The digital tachometer used in this process accounts for minimal error, but still notable. According to the physical handbook, the resolution of the instrument is .1 RPM between the range 2.5 RPM - 999 RPM, which was the range of RPM measured in this experiment. The accuracy of the instrument is ± 1 RPM. While some of the performance speeds may be impressive standing alone, this steam engine does not quite compare with many of the engines in the field today. For example, current gasoline engines used in cars idle between 600 RPM and 1000 RPM. This means that while this steam engine is able to achieve those numbers at high air pressures, the only comparison is to the slowest speed that those engines run on when the car is not moving. Also, car engines are used to accelerate rather quickly, which simply is not possible with the steam engine when pressurized air is generated through steam. Also, due to its size, the steam engine would not be able to fit in some smaller toys or machines. Therefore, this steam engine would mostly be implemented into medium sized toys, such as a single speed toy car. The steam engine could also power small electrical circuits, such as an LED. Finally, the steam engine could be implemented in light-duty machinery that requires minimal torque. Another main problem, however, is the energy required to generate the air pressure from steam. For the experimental phase, air pressure was used, which required an air compressor to run for a few minutes before testing could commence. Then, the steam engine could be used for a few minutes, however the air compressor would need to be turned back on. Using an air compressor does not allow for sustained operation of the steam engine. One way to generate sustained operation of the steam engine is to utilize the air pressure of steam. However, this requires a tremendous amount of heat energy to generate steam at that air pressure. For example, using the data in Table 1 of the Results section above, in order for the steam engine to run with a rotational speed of roughly 550 RPM, an air pressure of 10 psi is required. However, the temperature required to generate steam with a pressure of 10 psi is 239º.12
Using the equation Energy = cwatermwaterΔT , where c is the specific heat capacity of water, m is the mass of water per mol, and T is temperature in Kelvin, the energy required to heat
12 “Properties of Saturated Steam - Imperial Units.” Engineering Toolbox. Stabile 20
water/steam from room temperature (70º) to 239º is 7081 Joules of heat energy. This is a tremendous amount of energy, and a slow process. The only way in which the use of steam engines, like this one, is if the heat energy is collected through natural means. For example, nuclear energy harnesses the heat energy released when nuclear fission occurs. Some steam engines utilize the heat energy of the sun. This steam engine simply is not practical if the energy required to heat up the steam to achieve adequate air pressures is not harnessed from natural resources; too much energy would be required otherwise to run this steam engine, energy that would have better use elsewhere.
VII. The Next Steps While the project is finished, there are a few modifications that can be made to improve the performance of the steam engine. The first modification regards the crankshaft. Due to material on hand, the crankshaft was constructed using machined brass parts connected by stainless steel threaded rods. However, the next steps would be to whittle down unnecessary brass from the crankshaft to decrease the moment of inertia of the rotating body, or to use another material altogether. At the speeds that this engine is currently being tested, the combination of the brass and stainless steel connecting rods are adequately strong to handle the forces exerted on the crankshaft. However, if the steam engine were required to rotate faster, stronger materials could be used to ensure that the crankshaft would be able to handle the more intense stresses. Another modification is to add more cylinder assemblies and pistons. Gasoline engines use multiple pistons, all of which are exerting a force on the crankshaft during different stages of the cycle. Using more pistons ensures that a torque is constantly being exerted on the crankshaft at any given time, which increases its power and its rotational speed. The next step to this steam engine would be to add more working pistons; at this stage, only one piston is doing work on the crankshaft. Extending the crankshaft and adding more pistons will increase the performance of the steam engine. Finally, the last modification would be to add washers around the rod connections between the pistons and the crankshaft, eliminating some of the “wiggle room” around those parts. Due to the parts being able to move, the unwanted movement disrupts a smooth cycle, which slows down the crankshaft rotational speed.
VIII. Acknowledgements When school was cancelled due to COVID-19, I was worried that I would not be able to complete my second semester ASR research project, a project that I had been looking forward to for multiple years. Seeing as I had started to make plans for the project and I was started to get really excited to start building the steam engine, I was really bummed when school got cancelled and a shelter in place was implemented. My project required some heavy machinery that was not available in Whitaker, and was provided to me by Dr. Dartt. I am very appreciative for his assistance in making my project; without him, I would not have a beautiful, working steam engine in front of me. He was accommodating to my schedule, he offered advice throughout the process, and he allowed me to continue to use the machinery at his house, even during the shelter in place due to COVID-19. Thank you Dr. Dartt! Stabile 21
I also just wanted to thank Dr. Dann (and MacMaster Carr) for ordering, shipping, and delivering the materials needed for my project to the place where I needed them to be, especially during quarantine. Thank you Dr. Dann!
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Bibliography
“Brief History of the Steam Engine.” Steam Engine History, www.egr.msu.edu/~lira/supp/steam/.
“Carnot Cycle.” Carnot Cycle, hyperphysics.phy-astr.gsu.edu/hbase/thermo/carnot.html. “The Effects of Climate Change.” NASA, NASA, 30 Sept. 2019, climate.nasa.gov/effects/. “The Efficiency of the Carnot Cycle.” ResearchGate, www.researchgate.net/figure/The-p-V-indicator-diagram-of-a-Carnot-cycle-1-2-3-4-wher e-T-C-T-H_fig1_231065936.
“How to Make a Free Energy Steam Engine at Home.” YouTube, YouTube, www.youtube.com/watch?v=DKWquu9ood8.
“How to Make a Stirling Engine.” YouTube, YouTube, www.youtube.com/watch?v=FCjYZT6FJm4.
“Ideal Gas Law.” Ideal Gas Law, hyperphysics.phy-astr.gsu.edu/hbase/Kinetic/idegas.html. “Nuclear Power Is Essential for Energy, Environment, & the Economy.” Nuclear Power Is Essential for Energy, Environment and the Economy - World Nuclear Association, www.world-nuclear.org/press/briefings/nuclear-power-is-essential-for-energy-environme nt.aspx.
“Properties of Saturated Steam - Imperial Units.” Engineering ToolBox, www.engineeringtoolbox.com/saturated-steam-properties-d_273.html.
“Sources of Greenhouse Gas Emissions.” EPA, Environmental Protection Agency, 13 Sept. 2019, www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions.
“Stirling Cycle.” Simon Fraser University, www.sfu.ca/~mbahrami/ENSC%20461/Notes/Stirling%20Cycle.pdf.
“U.S. Energy Information Administration - EIA - Independent Statistics and Analysis.” Nuclear Power Plants - U.S. Energy Information Administration (EIA), www.eia.gov/energyexplained/nuclear/nuclear-power-plants.php.
“Watt Steam Engine.” Wikipedia, Wikimedia Foundation, 17 Mar. 2020, en.wikipedia.org/wiki/Watt_steam_engine.
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