Design and Construction of Insulation Test Bunker

Transcription

1 Design and Construction of Insulation Test Bunker D Lab II Dr. Kurt Kornbluth June 14, 2018 Aina Smart Truco Mark Susanto

2 BACKGROUND: Working with the Horticulture Lab The Insulation Test Bunker is a structure that can be used to test the insulated capacities of different materials. This box is a 3 x 3 x 2 exterior and 2 x 2 x 2 interior structure, made from ½ inch plywood boards, with four hollow walls that can simultaneously contain different insulation materials. Two of the walls can contain a 6 x 3 x 2 volume of materials, and the other two walls can contain a 6 x 2 x 2 volume of materials. The top and bottom of the box is insulated with professional graded foam, and one of the walls (the control ) contains fiber glass material with an R-value of 26. This box can be used test the insulated capacity of materials by cooling the interior of the box with a bucket of ice, and consistently monitoring the changes in temperature of the exterior walls over an extended period (around 4-8 hours). This box was created for the Horticulture Innovation Lab as a tool to further collect data on materials insulative capacities, which will later inform projects being done by the lab related to insulation, cooling systems, and refrigeration structures. For the past 10 years, the Horticulture Innovation Lab has been developing different cooling technologies, and insulative structures, to aid communities facing post-harvest loss in the USAID identified Feed the Future Countries (Cambodia, Ethiopia, Ghana, Guatemala, Haiti, Mali, Malawi, Mozambique, Kenya, Nepal, Rwanda, Senegal, Tajikistan, Tanzania, Uganda, Zambia). Rural farmers in these 16 countries are estimated to lose approximately 45% of their post-harvest produce, before they can sell their product. Produce in these areas rots quickly because of the common hot and humid climate of each of these regions and many of these farmers lack the financial, energy, and local resources to invest in any sort of refrigeration/cooling system that would preserve their product. From this dilemma, the Horticulture Innovation lab has been trying to design a cheap, efficient, locally sourced, and off the grid insulative structure that could be distributed or built by farmers struggling with this issue of post-harvest loss. Previous projects done by the Horticulture Innovation Lab (including the Cool Bot/Cool Room, and the Zero Energy Cooling Chamber or ZECC) resulted as much too expensive for rural farmers to invest in (both projects) and inefficient at cooling (ZECC project). From this work the Horticulture Innovation Lab is during coming up with a new project, to design an ice bunker chamber that will not only be affordable to farmers but made with locally sourced materials and act as an effective insulation chamber without any reliance on an external power source. For this design, the currently needs more data on the types of materials that could be used for effective insulation, and that would be cheap and accessible for rural farmers to build with. Our project goal through the D-Lab was to design a testing structure to would better inform the Horticulture Innovation Lab of materials insulative capacities. This involved creating a structure that could be used multiple times and that would provide clear data information to guide future design projects. 1

3 DESIGN PROCESS: Criteria and Metrics The five main criteria that informed our final design are as follows. COSTS Our budget was $300 total, and our mindset for the projects spending was the cheaper the better. The budget was high priority throughout the design process, for both the things needed to create and test the structure, and the materials being tested. For the structure of the Insulation Testing Bunker, we had to keep spending within our budget limitations, making sure that all materials purchased did not exceed the 300-dollar limit. For the materials being tested, not only were we thinking about their cost in the Davis area, but we had to seriously consider the cost of these materials in the Feed the Future Countries, the end customer for future projects. Materials had to be extra cheap, something that could be easily affordable to rural farmers. CONSTRUCTABILITY Our team for this project had a limited background in carpentry, construction, and building skills. From this basis, we focused on designing a structure that would be manageable to create at our skill level and within the limited time frame of the quarter (10 weeks total). This informed a simple design, where steps to build were straight forward and did not require using any tools or building materials that were difficult or unfamiliar to work with. INSULATED CAPACITY The function of the tests of the Insulation Testing Bunker is to get a general understanding of a materials R-value. The R-value is a unit of measure that communicates a material's capacity to resist heat flow (the movement of heat through space). Materials with lower R-values are more heat conductive and less insulating, and materials with higher R-values are less heat conductive and more insulating. Still air is the least heat conductive material, and solid materials that contain many tiny pocket of air (stopping heat conduction) are known to be the most effective insulators. For this project, materials tested were all chosen with these laws of physics in mind,. We concentrated our tests on agricultural waste materials, because of their organic fluffy build, and their cheap availability in many areas. Different plants have different waste products, some with larger amounts of waste produced, dryer textures, and a variety of builds (thickness, starchiness, etc). All these aspects of the waste products texture, abundance, and build influenced our choice of what waste to test. AVAILABILITY: Materials tested had to be a common and accessible material in a majority of the Feed the Future Countries. After doing some research on countries national agriculture production, we 2

4 were able to determine which products might be the most accessible materials to rural farmers in these countries. In Table 1, Amount of Countries Nationally Producing Agricultural Products, 9 different agricultural products are identified for countries that produce, on a nationally recognized scale each product. Data for this table was collected from the Country STAT Food and Agricultural Network hosted by the Food and Agricultural Organization of the United Nations (2018). The availability of products locally was also a component of how we chose what to test in the R-Testing Box. Because of the limited availability of certain materials in the Sacramento region (such as Cassava waste, bean waste, and coffee waste) we were unable to incorporate some of the more available products in these countries into this project. Also, previous criteria of material s insulation capacity informed our final decisions of what products to test. For example, we ended up testing rice hulls in the R-Testing Box, even though rice only had 6/16 country s nationally producing this agricultural product. This was due to the Horticulture Innovation Lab s interest in seeing how Rice Hulls would act as an insulator, because of the large amount of waste that rice creates and their hull s dry/fluffy texture. The final materials chosen for the testing phase of this project were rice hulls, hay and chicken feathers. Although chicken feathers do not appear on Table 1, they are available in all these countries (Food, 2018). 3

5 EFFECTIVENESS The Insulation Test Bunker had to be able to run clear and indicative test, meaning that its design had to consider the best way of analyzing a material insulated capacities with little room for error. We tried to use materials for the structure of the box that would have very neutral heat transfer capacities, and that would still be functional as a strong structure. We ended up using ½ inch plywood boards for the build of the Box, since plywood is a material with a low R- value (~1 unit per inch). By having a material that interfered minimally with heat conduction and insulation, we hoped this would make the Insulation Testing Bunker collect better data on the materials being tested. This criterion also informed the size of each hollow wall, where 6 was a size determined thick enough to create moderate insulation from each product being tested, regardless of actual R-values. This is important because it also gives researchers and idea of the thickness needed for materials to be more effective. SUSTAINABILITY Sustainability was an influential part of the overall design since the world of design is dramatically changing to where all good design now requires a sustainable perspective. In this project, the choice of testing agricultural waste materials was a part of this criteria, since agricultural waste is very accessible in developing communities. MOBILITY Finally, mobility was a factor we needed to consider, since our final product needed to be moved from the Student Farm area back to the Horticulture Innovation Lab display garden. This required that the final product having to fit into one of the vehicle s available for transportation. RESULTS Procedure Using the testing structure, we designed and built, we tested the insulative capacities of the rice hulls, rice straw and chicken feathers while using fiberglass with R-Value 26 as a control. The bottom and top of the structure were insulated with a foam board. In the inside of the structure, we added a bucket with pounds of ice and a fan to distribute the air. We placed a HOBO data logger on the inside of the structure, and one outside to measure the atmospheric temperature. A Seek Thermal infrared camera was used to measure the temperature of each wall. 4

6 Experimental Data Table 1 gives an overview of the experimental results. Figure 1 below shows the surface temperature of each wall that was insulated with each material throughout the day. Figure 2 compares the temperature inside the structure with the atmospheric temperature. Table 1: Overview of the Results Date 6/5/2018 Start Time 9:00 AM Ice Melted (lbs.) End Time 4:30 PM Average Internal Temperature (F) 56 Average Atmospheric Temperature (F) 79.5 Average Temp R-26 Fiberglass (F) 88 Average Temp Chicken Feathers (F) 86 Average Temp Rice Straw (F) 87 Average Temp Rice Hulls (F) 86 Figure 1: Plot of the Surface Temperature 5

7 Figure 2: Plot of the Interior Temperature vs Atmospheric Temperature CONCLUSION The data from this experiment is not very conclusive. The issue with the data is that the temperature difference from the wall surface temperatures did not very much. We were expecting each wall to have a significant change in temperature to compute the R-Value. The surface temperatures ranged from 75F to 95F throughout the day, while the temperature on the inside averaged 56F. The largest source of uncertainty is the instrumentation used. We were not able to find a way to calibrate the Seek Thermal Camera used to measure the surface temperatures of each wall containing different materials. Using a kitchen infrared thermometer, there was a 17F discrepancy with the Seek Thermal Camera. Based on the data, there are a few possible conclusions that could be made: all the materials have approximately the same insulative capacities as the fiberglass (R-26), the cold air from the structure is leaking, the plywood used to build the structure is not transferring heat as well as expected and instead is acting as an additional insulator. RECOMMENDATION: Improvements, Further Testing and Future Design Currently, the data collected from the experiments done with the Insulative Test Bunker, are not clear enough and don t concretely conclude any findings. There needs to be further testing to determine if the structure is effective. From the test, we determined that if the test is replicated, it needs to be a very hot day (100F) and more ice needs to be used to cool the inside 6

8 the structure. A possible test to conduct would be to redo the test we conducted with the ice in the center of the structure, but instead leave two of the walls empty and two with R-26 fiberglass. There should be a major discrepancy in between the surface temperatures of the walls with the fiberglass and the walls that are empty. Further testing of insulation on other agricultural waste products, and materials other than agricultural waste products, should take place. Additional tests not related to the insulation of the materials, but rather looking at characteristics that would influence future designs of an effective Ice Bunker should also be implemented. This would include testing materials longevity, the process needed for prepping materials, and the way rural farmers are even able to access and use these materials. These are other components that will go into informing the final design of an off the grid ice bunker structure that could be affordably put together by rural farmers at home and with materials that are locally available and sustainable. The next part of this project, after more information gathering and testing, is to work on a design for the final product that can then be produced in the Feed the Future Countries. This would require the design of a physical ice bunker (using ice as a form of refrigeration, relying on growing ice markets of these countries) that could use agriculture waste materials as an insulated lining. This bunker, like the intentions of the previous projects done by the Horticulture Innovation Lab, would be affordable to rural farmers, efficient in keeping produce cool although being off the grid, made of accessible local materials, and easy to construct by growers. 7

9 Bibliography Food and Agricultural Organization of the United Nations (2018). CountrySTAT. Retrieved from 8