When I started the heat and mass transfer class I was most interested in different insulation methods, how a radiator in a car functions, and how to effectively heat and cool different substances efficiently. The first major interest I have is insulation. Insulation is extremely important because it is used every day in a variety of fields and situations to reduce heat loss. I had always understood the basic concepts behind insulations but this course gave me a much deeper understanding. For instance, I learned that double pane windows are much more insulated than single pane windows. This is because the air in the middle acts as an insulator to heat transfer. By adding the air, additional resistance is added to the system. Resistance for conduction can be found by using the resistance equation,
L/kA,
and the resistance due to convection can be found by using the equation,
1/hA.
As resistance increases, so does the insulating power of you system.
In this class I also learned that there is a point where adding more insulation does not have a significant impact on your system. This is called the
critical radius and it can be found by the equation
r=K/h,
where r is the critical radius, K is the thermal conductivity, and h is the convection heat transfer coefficient. This equation is very useful because it will keep us as engineers from spending money on materials that are not helping insulate our system.
Another system I found very interesting was the radiator in a car. I always understood that the radiator kept the car engine cool but I was not sure how. No I know that the radiator in a car is actually a system of fins that are used to increase surface area and cool the engine more effectively. In this class we learned the equation
Q=((hPKA)^(1/2))*(Tb-Ts)
to find the amount of energy used when the fin is in place. We also explored topics such as fin efficiency and effectiveness to see if fins were necessary or useful at all.
One more thing that was very interesting to me was the study of how quickly something could be heated or cooled. In this class we learned how different materials affected the rate of heat transfer of different objects and we also explored how different shapes, such as cylinders versus spheres, could change the heating and cooling rates of objects. We studied the lumped parameter analysis and how that can be an effective way of determining heat transfer for objects that have much more heat transfer due to conduction than convection.
L/kA,
and the resistance due to convection can be found by using the equation,
1/hA.
As resistance increases, so does the insulating power of you system.
In this class I also learned that there is a point where adding more insulation does not have a significant impact on your system. This is called the
critical radius and it can be found by the equation
r=K/h,
where r is the critical radius, K is the thermal conductivity, and h is the convection heat transfer coefficient. This equation is very useful because it will keep us as engineers from spending money on materials that are not helping insulate our system.
Another system I found very interesting was the radiator in a car. I always understood that the radiator kept the car engine cool but I was not sure how. No I know that the radiator in a car is actually a system of fins that are used to increase surface area and cool the engine more effectively. In this class we learned the equation
Q=((hPKA)^(1/2))*(Tb-Ts)
to find the amount of energy used when the fin is in place. We also explored topics such as fin efficiency and effectiveness to see if fins were necessary or useful at all.
One more thing that was very interesting to me was the study of how quickly something could be heated or cooled. In this class we learned how different materials affected the rate of heat transfer of different objects and we also explored how different shapes, such as cylinders versus spheres, could change the heating and cooling rates of objects. We studied the lumped parameter analysis and how that can be an effective way of determining heat transfer for objects that have much more heat transfer due to conduction than convection.