After purchasing all of the necessary materials, and getting some generous tool donations from our mentor Dr. Schwartz, the team set out to build our final test section. We will be building two test sections that we can do our heating tests on indoor in an indoor freezer. The wires will be laid on duraroc, a cement board, that will be covered in asphalt sealant. The duraroc will be placed on a sheet of plywood which will be attached to a wooden frame for stability. This should provide for fairly easy transport of our test section aside from the size of the system.
The team made good progress today on building the test section, which will be split into a 2x8 foot section and a 4x8 foot section. Both wood frames were built and she plywood and duraroc were attached as well. The copper buses have also been attached and the wire casing has been stripped at the points where the buses will need to be soldered to the nickel chromium wires.
Construction went very well today and I am pleased with the progress we made. I feel we are on schedule right now for completing the test sections sometime next week.
All that remains in our construction is to solder all of the wires in the system and lay down the sealant. Out team hopes to finish construction sometime next week at the latest so we can begin our testing in the large freezers at comcast center.
~Jon
Wednesday, September 30, 2009
Saturday, May 9, 2009
Long Duration Test with Thermal Camera
We finally were able to get a window this Saturday where we could test our system for a few hours without the threat of rain, and the test did not disappoint!
Kyle, Travis and I got to the lab at 930 this morning and began setting up the circuit. By 10 we were ready to go and turned on the two transformers set up in parallel. We immediately tested voltages around the system and were confident that the system was working the way we expected.
We proceeded to use our thermometer to test surface temperatures at 7 different locations every 30 mins. We also got temperature readings every 30 mins at spots on the normal asphalt, and a darker shade of asphalt so as to have control temperatures to compare our results too. We noticed a slight heating but it was hard to tell what was really going on.
Charlie came by and helped us take some more readings and then Nelson Gibson, a former student of our mentor showed up around 1215 with his infrared camera and took pictures of our system after it had been on for a little over 2 hours.
The pictures showed us that yes, our system is creating heat along the wire paths. Unfortunately, it also showed that our triplet wires were not producing much heat, and that the heat was not spreading very far from the wires. Nevertheless, the information these pictures will provide will be very valuable and will help us decide where we go from here. We would like to thank Nelson very much for donating his time and services to our team!
After the test was concluded, the team members on the site decided we did not want to completly rip up the system as it had provided us with some good data and might still be of use to us later. We opted to rip up the bottom 4th of the system as it was in bad shape, and then cover the remainder of the system with a layer of sealcoat. The parking space is now in good enough shape that we are confident people can park on it and walk on it without fear of tripping or puncturing a tire.
Today's test was a big success and has given us lots of good information on how to proceed in the future. Next semester we aim to lay down a better version of the system based on the information we learned throughout this semester so we can test during the winter months next school year.
Check out the Team SnowMelt website for thermal images from the tests we ran today. Kyle should be posting them soon!
~Jon
Kyle, Travis and I got to the lab at 930 this morning and began setting up the circuit. By 10 we were ready to go and turned on the two transformers set up in parallel. We immediately tested voltages around the system and were confident that the system was working the way we expected.
We proceeded to use our thermometer to test surface temperatures at 7 different locations every 30 mins. We also got temperature readings every 30 mins at spots on the normal asphalt, and a darker shade of asphalt so as to have control temperatures to compare our results too. We noticed a slight heating but it was hard to tell what was really going on.
Charlie came by and helped us take some more readings and then Nelson Gibson, a former student of our mentor showed up around 1215 with his infrared camera and took pictures of our system after it had been on for a little over 2 hours.
The pictures showed us that yes, our system is creating heat along the wire paths. Unfortunately, it also showed that our triplet wires were not producing much heat, and that the heat was not spreading very far from the wires. Nevertheless, the information these pictures will provide will be very valuable and will help us decide where we go from here. We would like to thank Nelson very much for donating his time and services to our team!
After the test was concluded, the team members on the site decided we did not want to completly rip up the system as it had provided us with some good data and might still be of use to us later. We opted to rip up the bottom 4th of the system as it was in bad shape, and then cover the remainder of the system with a layer of sealcoat. The parking space is now in good enough shape that we are confident people can park on it and walk on it without fear of tripping or puncturing a tire.
Today's test was a big success and has given us lots of good information on how to proceed in the future. Next semester we aim to lay down a better version of the system based on the information we learned throughout this semester so we can test during the winter months next school year.
Check out the Team SnowMelt website for thermal images from the tests we ran today. Kyle should be posting them soon!
~Jon
Friday, May 8, 2009
We Have Heat!
Well at least a little...
After several weeks of frustration with the outdoor test grid, we believe that we finally had some success! After about 5min of power, the grid heated up the pavement from a temp of 22 C to 25-27C even 30C on top of the wires. Finally some good results coming at the perfect time, the day before we are scheduled to preform our long duration testing.
In our original testing with the outdoor grid, we had been using an estimated 20 gauge copper wire to connect the two transformers in our single transformer unit in parallel as well as the transformer unit to the buses. Because of the high gauge of the wire, there was a large voltage drop in the wire connected due to the high current. This caused us to lose 4V from the expected voltage at the top of the buses. We were able to measure the voltage across a wire branch near the bottom of the circuit at ~10V. This means we are losing another 4V in the buses. These loses were unexpected in the theoretical calculations and have thrown our resulting power and heat generation numbers off.
With the above setup I can estimate the following:
Considering the loss in the buses, I can estimate a 11V drop in a NiCr wire near the middle of the grid
V = IR, I = V/R = 11/8 = 1.375
P = (I^2)(R) = (1.8906)*(8) = 15.125 W
Today, we hooked two transformer units in parallel, so that we had 18V at 100A. We also used 8 gauge wire for all the transformer connections. With this setup we had a 16V drop between the buses, so we gained 2V. The remaining 2V are still being lost in the transformer to transformer connects. We also still have a 4V loss within the two buses at the end of the grid.
Preforming the same calculations:
Considering the loss in the buses, I can estimate a 13V drop in a NiCr wire near the middle of the grid.
V = IR, I = V/R = 13/8 = 1.625
P = (I^2)(R) = (2.6406)(8) = 21.125W
So we were able to gain 6W by using the larger gauge of wire. However the question arises is this really enough of a power difference for us to suddenly be able to observe such a obvious temperature increase. In todays quick trial, it was much warmer outside. The initial temperature of the pavement was about 22C as compared to 10-11C in past trials. Our small scale lab tests suggest that this should not be an issue, but in the large-scale I wonder if when it is colder, we lose more heat to the ground.
Another possible path to take to increase the power would be to connect the two transformer units in series. This would theoretically give us 36V at 50A. We know that ideally our .5 ohm grid would draw 72A with a 36V drop across it. However we know that there will be losses inside the connections within the transformers. The situation still needs to be more carefully considered so that we are sure we do not damage the transformers.
Thats all for now, expect another post later this weekend detailing the results of our long duration testing
~Kyle
After several weeks of frustration with the outdoor test grid, we believe that we finally had some success! After about 5min of power, the grid heated up the pavement from a temp of 22 C to 25-27C even 30C on top of the wires. Finally some good results coming at the perfect time, the day before we are scheduled to preform our long duration testing.
In our original testing with the outdoor grid, we had been using an estimated 20 gauge copper wire to connect the two transformers in our single transformer unit in parallel as well as the transformer unit to the buses. Because of the high gauge of the wire, there was a large voltage drop in the wire connected due to the high current. This caused us to lose 4V from the expected voltage at the top of the buses. We were able to measure the voltage across a wire branch near the bottom of the circuit at ~10V. This means we are losing another 4V in the buses. These loses were unexpected in the theoretical calculations and have thrown our resulting power and heat generation numbers off.
With the above setup I can estimate the following:
Considering the loss in the buses, I can estimate a 11V drop in a NiCr wire near the middle of the grid
V = IR, I = V/R = 11/8 = 1.375
P = (I^2)(R) = (1.8906)*(8) = 15.125 W
Today, we hooked two transformer units in parallel, so that we had 18V at 100A. We also used 8 gauge wire for all the transformer connections. With this setup we had a 16V drop between the buses, so we gained 2V. The remaining 2V are still being lost in the transformer to transformer connects. We also still have a 4V loss within the two buses at the end of the grid.
Preforming the same calculations:
Considering the loss in the buses, I can estimate a 13V drop in a NiCr wire near the middle of the grid.
V = IR, I = V/R = 13/8 = 1.625
P = (I^2)(R) = (2.6406)(8) = 21.125W
So we were able to gain 6W by using the larger gauge of wire. However the question arises is this really enough of a power difference for us to suddenly be able to observe such a obvious temperature increase. In todays quick trial, it was much warmer outside. The initial temperature of the pavement was about 22C as compared to 10-11C in past trials. Our small scale lab tests suggest that this should not be an issue, but in the large-scale I wonder if when it is colder, we lose more heat to the ground.
Another possible path to take to increase the power would be to connect the two transformer units in series. This would theoretically give us 36V at 50A. We know that ideally our .5 ohm grid would draw 72A with a 36V drop across it. However we know that there will be losses inside the connections within the transformers. The situation still needs to be more carefully considered so that we are sure we do not damage the transformers.
Thats all for now, expect another post later this weekend detailing the results of our long duration testing
~Kyle
Sunday, February 22, 2009
Power Problems
After a rather fruitless search to find an arc wielder that would be able to supply our power needs, the lab group has taken matters into our own hands. Since our power needs are very unusual, we require 20V at 100A for a 100% duty cycle, only the high-end arc wielders are able to provide us with the right amount of power. Not only are these arc wielders outside of our price range, but the require high voltage, high amperage power circuits which our lab does not have.
So we have decided to, in a way, build our own power supply. Our current plan is to create a network of transformers to power the system.
Today in the lab, Travis, Jon and myself tested to see if transformers in parallel would work the same way as resistors. This means the voltage across the transformers would be equal, in this case they supplied 12.6V, but the current through the transformers would sum up to the total current in the circuit. After running several tests we were able to observe a 5.34A current through a melting 2 ohm resistor. The resistor was only rated to 10W so the longer we ran the circuit, the more the resistor failed. This is a very promising result because it means that we can use multiple transformers in parallel to allow us to reach a high current at around 20V.
The only hesitations I have still is that we did not run the transformers very long, I expect that the transformers should be able to exceed 3A by themselves for short periods of time, so this could be what was happening. Unfortunately any attempt to run the transformers longer than 20-30 seconds or so was prevented because the resistors hit about 210 degrees C according to our infrared thermometer. I also did not think to test the current through each transformer, so we can't be sure if one had more load than the other.
Oh and I thought I would mention Travis had fun lighting up a section of NiCr wire like a toaster by putting 6A through it. We measured temps of around 210 degrees C!!
~Kyle
So we have decided to, in a way, build our own power supply. Our current plan is to create a network of transformers to power the system.
Today in the lab, Travis, Jon and myself tested to see if transformers in parallel would work the same way as resistors. This means the voltage across the transformers would be equal, in this case they supplied 12.6V, but the current through the transformers would sum up to the total current in the circuit. After running several tests we were able to observe a 5.34A current through a melting 2 ohm resistor. The resistor was only rated to 10W so the longer we ran the circuit, the more the resistor failed. This is a very promising result because it means that we can use multiple transformers in parallel to allow us to reach a high current at around 20V.
The only hesitations I have still is that we did not run the transformers very long, I expect that the transformers should be able to exceed 3A by themselves for short periods of time, so this could be what was happening. Unfortunately any attempt to run the transformers longer than 20-30 seconds or so was prevented because the resistors hit about 210 degrees C according to our infrared thermometer. I also did not think to test the current through each transformer, so we can't be sure if one had more load than the other.
Oh and I thought I would mention Travis had fun lighting up a section of NiCr wire like a toaster by putting 6A through it. We measured temps of around 210 degrees C!!
~Kyle
Monday, February 9, 2009
Reflections on Outdoor Lab Sessions 2/7 and 2/8
I was very pleased with how the lab sessions went over the weekend. I had been worried about our ability to get the nickle chromium wires to stay down low enough so they would be covered when we put down sealant, but the idea of masonry nails and washers that Kyle and I came up worked even better than expected in my opinion.
I am a bit surprised at how much sealant we went through (2 whole buckets between both coats we laid down), but the important thing is we got everything covered. We added a lot of sand to the sealant, about 35 dixie cups of sand per container of sealant, which is more than I expected we would need, but the sealant just was not getting thick enough with smaller amounts of sand. I am still a bit confused as to why the hydrated lime was so poor in our trials and it may be worth while to contact Ray as to what we may have done wrong. It was just very evident from the field trial from the previous week and the small experiment that Travis and I did in lab that it was causing the cracking on the surface of the sealant as well as the visible white streaks.
I hope we can locate a Power Supply soon as the cold weeks of winter are starting to run out and we really need to test the system now that it is built. Nonetheless, I am very pleased with the progress the team has made this past weekend and look forward to seeing the system in action. I spent a total of 13 hours over three days the past 2 weekends setting up the system and I hope my work was not for nothing and the system will do what it is intended to do, or at the very least give us some good knowledge on how to improve the system.
~Jon
I am a bit surprised at how much sealant we went through (2 whole buckets between both coats we laid down), but the important thing is we got everything covered. We added a lot of sand to the sealant, about 35 dixie cups of sand per container of sealant, which is more than I expected we would need, but the sealant just was not getting thick enough with smaller amounts of sand. I am still a bit confused as to why the hydrated lime was so poor in our trials and it may be worth while to contact Ray as to what we may have done wrong. It was just very evident from the field trial from the previous week and the small experiment that Travis and I did in lab that it was causing the cracking on the surface of the sealant as well as the visible white streaks.
I hope we can locate a Power Supply soon as the cold weeks of winter are starting to run out and we really need to test the system now that it is built. Nonetheless, I am very pleased with the progress the team has made this past weekend and look forward to seeing the system in action. I spent a total of 13 hours over three days the past 2 weekends setting up the system and I hope my work was not for nothing and the system will do what it is intended to do, or at the very least give us some good knowledge on how to improve the system.
~Jon
Sunday, February 8, 2009
Welcome to the Team SnowMelt Blog
Welcome to the Team SnowMelt Official Team Member Blog!
Team SnowMelt is an undergraduate multidisciplinary research team seeking to bring an end to shoveling snow. As part of the Gemstone Program at the University of Maryland, we will gather information, perform lab tests and develop the SnowMelt product over the next four years. At the end of our senior year, SnowMelt will defend our findings at the annual Gemstone Thesis Conference. For more information on research, news, and photos please visit our homepage at http://teams.gemstone.umd.edu/classof2010/snowmelt/index.html
The following posts will include team member experiences as we continue our work on the SnowMelt project
-Kyle
Webmaster
Team SnowMelt is an undergraduate multidisciplinary research team seeking to bring an end to shoveling snow. As part of the Gemstone Program at the University of Maryland, we will gather information, perform lab tests and develop the SnowMelt product over the next four years. At the end of our senior year, SnowMelt will defend our findings at the annual Gemstone Thesis Conference. For more information on research, news, and photos please visit our homepage at http://teams.gemstone.umd.edu/classof2010/snowmelt/index.html
The following posts will include team member experiences as we continue our work on the SnowMelt project
-Kyle
Webmaster
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