Landfill gas is often left to rot and waste the environment. However, would it be possible if we could actually do something with this corrosive material? Well, let’s use our engineering mindsets to think about this. We know that gasses are transported through piping systems to provide energy. So what is we were to replace these glasses with the methane gasses released by landfills? This system is known as landfill gas to energy and is often used for generating electricity, replacing non-renewable resources, cogeneration, and pipeline gas
Humanity has two problems. Our levels of waste are piling up every year, destroying available land storage space. We also do not have enough energy to supply everyone on the planet. However, what if we could solve these two problems at once? Well, let’s think about it with our engineering mindset. We know that traditional energy generation methods such as coal and nuclear power involve the decomposition of a material to heat water into steam to drive a turbine. So what if we were to simply burn waste instead? This energy generation method is known as an incineration waste to energy generator and is used all over the world to generate electricity.
“How can we capture carbon dioxide directly from the air?” There is a global problem. Carbon dioxide emissions from industrialization have polluted the atmosphere to the point where a worldwide rise in temperatures has been induced. However, would it be possible if we could use our engineering mindset to take CO2 out of the atmosphere? Well, let’s start by using a little bit of knowledge of basic science. There are chemicals that are able to capture CO2 through a “sticking” process while leaving other atmospheric molecules such as nitrogen and hydrogen unabated, therefore creating a barrier. And this mechanism can then be heated such that the CO2 molecules are free from the material, allowing new CO2 to come in. So what if we were to take a pool of industrial fans, stack them up in rows and columns, place a CO2 absorbing material behind it and have them suck up all of the air? This method is known as Direct Air Capture and can be used to help in the fight against global warming
“Is there a thermodynamic process with no heat exchange?” When most people think of thermodynamics, one of the first thing that pops into people’s minds is one phenomenon, heat flow. However, is it possible to have such a process with no heat flow? Well, let’s think about it. If we were to take our system and completely isolated it inside an insulator, no heat would be able to flow in or out. Therefore, all of the work done must come from the internal energy. This phenomenon is known an adiabatic process. In an adiabatic process, the pressure multiplied by the volume raised to the ratio of the specific heats of the gas is always equal to a constant (PV^(c_p/c_v)), leading to a steeper PV diagram than the isothermal process.
“Can we have a thermodynamic process in which the temperature of the system remains constant?” When working with thermodynamic systems, it is very easy for the internal temperature to change when other properties change as well. However, is it possible to have a fixed constant temperature process? Well, let’s think about how this can be accomplished. We know that when a system does work (such as a gas expanding) it will lose some of its internal energy and therefore cooling it. However, if we were to then supply heat to counteract this loss, the temperature would remain consistent, therefore resulting in what engineers and scientists call an isothermal process. In an isothermal gas expansion, the change in volume is directly equal to the number of moles present in the gas times the (fixed) temperature times universal gas constant divided by the change of pressure, which can be summarized symbolically as (Delta)V=nRT/(Delta)P. Isothermal processes are used to study highly structured mechanical systems such as Carnot cycles and chemical reactions.
“What is the most efficient possible heat engine?” The Heat engine is one of the most productive inventions of humanity, allowing our civilization to take in exterior heat and channel it into useful energy. However, since there are so many different processes to choose from, which one is the most efficient? Well, let’s think about it. A heat engine cycle can be boiled down (pun definitely intended) to one core principle, an oscillation between a hot temperature and a cold temperature. One very efficient way to accomplish this is to have an isothermal process to expand the gas for a given amount and then use an adiabatic one to cool it down while further expansion takes place. Then, one can reverse this process by using an isothermal compression combined with an adiabatic one to raise the temperature and pressure back up to the original value, therefore completing the process known as a carnot cycle.
“How can we calculate the maximum efficiency of a heat engine?”
Due to the second law of thermodynamics, physics proves that there is a limit to the efficiency of all heat engines. However, we know that from practical experience that some heat engines are more efficient than others. So how can we predict what the maximum efficiency of a heat engine can be? Well, engineers and physicists have thought about this same problem for many long years, and after deep exploration into the subject an equation known as the carnot efficiency has been fabricated. This equation states that the maximum efficiency of an engine is the difference between the maximum temperature and the minimum temperature divided by the max temperature, or that (nu) = (T_max-T_min)/t_max. As a result, the efficiency can never be greater or equal to 100%, and if there is no difference in the temperature the maximum possible efficiency is 0%
“How can we turn heat into useful energy?” It is a well-known fact that energy can be converted into heat. However, is it possible to accomplish the opposite? Well, let’s think about it. We know that if we connect two points with different temperatures, then a heat flow will take place. And since this means that there is a transfer of energy, it can be redirected into useful work. A machine that accomplishes this is known as a heat engine, which is used in everyday life from jet engines to electricity generators.
“How can we use machines to heat up fluids?” We use warm fluids in our lives every day, whether it be in the showers we take, the HVAC systems that make our homes cozy or in our electrical generators. However, how exactly can we heat up such fluids? Well, let’s use our engineering mindset to find out. We know that if left to the surroundings, the heat from a fluid will radiate out. So if we were to place this fluid into a container, then logically the heat would be trapped inside. Furthermore, let’s control the temperature of this fluid by placing the container near a combustible source as to constantly supply energy. After constructing this, we will have ourselves what engineers have termed a boiler. Such machines are vital to the operation of our infrastructure, whether it be in the engines of trains or for culinary purposes.
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