Month: April 2017

Isothermal process

Isothermal process

Isothermal process

04/30/17

“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.

Carnot cycle

Carnot cycle

Carnot cycle

04/29/17

“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.

Carnot efficiency

Carnot efficiency

Carnot efficiency

04/28/17

“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%

Heat engine theory

Heat engine theory

Heat engine theory

04/27/17

“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.

Driving cycle

Driving cycle

Driving cycle

04/26/17

“How do engineers analyze the speed of an automobile?”
The Automobile is one of the most omnipresent devices on the planet. And as such, when being analyzed, all studies must be done with great precision. So how can engineers look at one component, velocity, with extreme detail? Well, thanks to the hard labors of many researchers, a tool known as the drive cycle has been developed. In essence, a drive cycle is a collection of data points representing a vehicle’s velocity in contrast to time. This system is often used by engineers to estimate the amount of fuel that a car has used since a car operating at higher speeds will burn more petroleum.

Boilers

Boilers

Boilers

04/25/17

“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.

Magnetic attraction bearings

Magnetic attraction bearings

Magnetic attraction bearings

04/24/17

“How can we use magnetic attraction to make bearings?”

 

Conventional mechanical bearings are limited by the effects of mechanical friction which impinges their durability, speed, and control. However, by removing physical contact with the shaft, the bearing will become far more optimal. So how could we implement such an idea into reality? Well, one method is to use the physical mechanism of magnetic attraction to remotely control the bearings. Such magnetic attraction bearings would be freed from the limitations of traditional mechanisms and could provide for far more efficiency. However, due to chaotic nature of rotation, a self-centering device must be used with such mechanisms, so that no side becomes too close to the magnetic center and therefore lose balance. Such conundrums can be remedied with magnetic repulsion models.