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===Solar Systems=== | ===Solar Systems=== | ||
The proper size solar panel that is required depends on the power requirements of your pump. Locate the manufactures maximum wattage and amperes off of their flow rate curves. Once this information is obtained, take the wattage that is required (make sure the minimum requirements from the manufacturer are met) and multiple it by 1.25.<ref name="Morales" | The proper size solar panel that is required depends on the power requirements of your pump. Locate the manufactures maximum wattage and amperes off of their flow rate curves. Once this information is obtained, take the wattage that is required (make sure the minimum requirements from the manufacturer are met) and multiple it by 1.25.<ref name="Morales"/> This will compensate for potential power loss due to dust, cloud cover, as well as the age of the solar panels.<ref name="Morales"/> If multiple panels are required, they should be wired in a series in order to provide the proper voltage required by the pump.<ref name="Morales"/> | ||
The installation equipment for the solar panels should come with the panels from the manufacturer. Using these mounting brackets will be the best option for the panels for long term installation. In order to maximize incoming solar rays, the panel should be south facing <ref name="Morales"/>. Since we will be mostly using the power from these panels in the winter months, we will install them in accordance with the sun being lower in the sky, as we are located in the northern hemisphere. To maximize production, take your latitude in degrees and add 15 degrees to it, this is the angle that you should install your solar panel.<ref name="Morales"/> This adjusts the panel to gather the maximum solar energy throughout the winter months. If your demand is higher in the summer months, then take your latitude and subtract 15 degrees from it. <ref name="Morales"/> | The installation equipment for the solar panels should come with the panels from the manufacturer. Using these mounting brackets will be the best option for the panels for long term installation. In order to maximize incoming solar rays, the panel should be south facing <ref name="Morales"/>. Since we will be mostly using the power from these panels in the winter months, we will install them in accordance with the sun being lower in the sky, as we are located in the northern hemisphere. To maximize production, take your latitude in degrees and add 15 degrees to it, this is the angle that you should install your solar panel.<ref name="Morales"/> This adjusts the panel to gather the maximum solar energy throughout the winter months. If your demand is higher in the summer months, then take your latitude and subtract 15 degrees from it. <ref name="Morales"/> | ||
Revision as of 03:51, 30 January 2017
Background
CCAT, the Campus Center for Appropriate Technology, has installed a rainwater catchment system on both the main building, as well as a garden shed, originally created in 2008, and updated in 2014.
These two rainwater systems operate independently of each other. The system installed on the main building has begun to pose some issues due to overflow and age, so needs to be updated. This main building system consists of newly installed rain gutters all around the roof of the building, draining in one central location. At this location, a screening system has been created to keep leaves, and debris from entering the rain catchment system. This water then flows through a series of pipes where it reaches the first flush system and the main storage tank. The first flush system consists of a fifteen gallon tank that collects the first bout of rainwater from a storm and keeps it separate from the main tank, as this water usually contains high levels of dust and pollen. Once this tank fills up, the float device then diverts the rainwater into the main storage tank that has the capacity of 1,500 gallons. CCAT is looking to increase their water storage capacity and potentially install a new tank on site to ideally double their capacity. They are also interested in an update of the piping system as well as the overflow relief valve.
Their second rainwater catchment system is in place on their garden shed. There is one gutter, with a screening system, that collects water and deposits it into a large tank next to the building. This tank sits level with the grounds, and so the CCAT team is looking to redesign the system in order to increase water pressure for watering purposes, and increase storage capacity.
Problem statement
The objective of this project is to redesign the current rainwater catchment system on the main building of CCAT, the Campus Center for Appropriate Technology. Our goal is to increase their storage capacity, and redesign the conveyance system from the house gutters, to the storage tank. We also will update the relief valve and create appropriate and easy to read instructions and labels for all portions of the rainwater catchment system.
The secondary objective of this project is to completely redesign the rainwater catchment system for the garden shed. This system needs to have a first flush system installed, as well as a new storage tank placed higher up on the hillside above the garden shed in order to provide adequate water pressure for watering purposes on CCAT's grounds. To accomplish this, a solar water pump system needs to be designed, as well as appropriate pipes and float systems. The purpose of this catchment system is to pump water from the downhill storage tank up to the uphill storage tank during the day with the solar pump. We will need to design a float system in order to automate the pump and keep the top tank from over filling, and the downhill tank from pumping while dry.
Literature Review
This is a review of the available literature pertinent to the CCAT Rainwater Catchment project.
CCAT
Climate
Precipitation data shows that Eureka, CA received just over 36 inches of rain between October 1, 2017 and January 28, 2017. This is 166% of the estimated 'normal' rainfall for these months. Similarly, the same time period received approximately 31.5 inches in 2016, 144% of 'normal' rainfall. This is a large portion of the rainy season for Humboldt County. In addition, the greatest recorded amount of precipitation in a 24-hour period for Eureka, CA during 2016 is 2.74 inches, so we can expect that CCAT may not receive more than this in any given day.[1] The average recorded wind speed in 2016 for Eureka, CA was 4.9mph.[2] So far for January 2017 in Arcata, CA the total precipitation is 11.03 inches, and the highest recorded wind speed is 50mph.[3]
Rainwater Catchment Basics
Uses of Rainwater
When rainwater is harvested it can be used for many purposes. The main use for stored rainwater is watering agricultural crops. CCAT uses its rainwater for this purpose. Another option is to use the water in a residential setting by filtering the water for drinking/washing or reusing it as non-drinking water(toilets, outdoor hoses, etc). [4]
Maintenance & Components
Sizing
Solar Pumping
Solar pumps can be very beneficial when utilized in a rainwater catchment system. A solar pump operates when the sun is shining and pumps water. Some pump from a collection tank attached to the downspout, to a secondary tank, normally at a higher elevation. Water gains approximately 1 psi, or pound per square inch of pressure, for every increase of 2.31 feet in elevation.[7] So, in order for us to utilize this rainwater for irrigation purposes, we need to achieve a minimum psi of 20, as this will allow us to utilize sprinklers for irrigation. [7] In order for us to achieve 20 psi, we need to place the secondary tank approximately 46 feet above the intended watering area. This can be achieved by using a pump at the downhill storage facility. There are two options for pumps that can be used, a 120 volt pump or 12 volt. Since we want to use solar as our power source, we want to use a 12 volt pump. Solar panels produce a constant 12v direct current which we can directly attach to the pump, eliminating the need for a power inverter or a battery.[8] The benefit of utilizing solar as a power source that is directly wired to the pump, allows the pump to automatically run when the sun is out.
Solar Systems
The proper size solar panel that is required depends on the power requirements of your pump. Locate the manufactures maximum wattage and amperes off of their flow rate curves. Once this information is obtained, take the wattage that is required (make sure the minimum requirements from the manufacturer are met) and multiple it by 1.25.[8] This will compensate for potential power loss due to dust, cloud cover, as well as the age of the solar panels.[8] If multiple panels are required, they should be wired in a series in order to provide the proper voltage required by the pump.[8]
The installation equipment for the solar panels should come with the panels from the manufacturer. Using these mounting brackets will be the best option for the panels for long term installation. In order to maximize incoming solar rays, the panel should be south facing [8]. Since we will be mostly using the power from these panels in the winter months, we will install them in accordance with the sun being lower in the sky, as we are located in the northern hemisphere. To maximize production, take your latitude in degrees and add 15 degrees to it, this is the angle that you should install your solar panel.[8] This adjusts the panel to gather the maximum solar energy throughout the winter months. If your demand is higher in the summer months, then take your latitude and subtract 15 degrees from it. [8]
Pumping
It is important to use the correct size pump for your pumping purposes. First you must determine your pumping height that is required. Then review manufacturers’ specifications for how high a pump can push the water. Ideally, you want to find a pump that can pump water higher than your ideal location. This will allow the pump to not work as hard to move the water. You must also take into account the distance that the pump must push the water. Positive displacement pumps can move lower flows daily, but can push the water to higher levels, 30-150m, while submersible centrifugal pumps are best for high flow rates and medium pumping heights, 10-30m. [9] To determine the total relative ‘height’ that the water moves, the friction from the sides of the pipe must be included. The friction, or head loss, for schedule 40 PVC plastic piping varies depending on the diameter of the pipe as well as the amount of water that is flowing through it.[8] A friction head loss sheet should be available from the manufacturer. From there you can calculate the loss per 100 feet of piping, (length of pipe x head loss = friction head loss in feet).[8] Once you have calculated your total head loss due to friction, add this value to your pumping height.[8] This is your minimum height requirement that your pump must be able to achieve in order for your system to work.
Water Conveyance
Conveyance systems for pumping systems consist of everything from PVC piping, to copper pipe, and even flexible rubber tubing. The tubing/piping system can be customized to fully meet your needs and utilize whatever materials are at hand. The only thing to make sure of when designing your conveyance system is that the diameter of the tubing is not going to restrict water flow due to its size. The other thing to keep in mind is different materials have different friction rates for water flow. So make sure to locate the correct friction head loss sheet to correctly calculate the additional friction your tubing option will add to the overall water pressure for the pump. [8]
Example Systems
Example 1
Example 2
Example 3
References
- ↑ NOAA. 2017. "California Climate Station Precipitation Summary." Last Modified January 28. http://www.cnrfc.noaa.gov/awipsProducts/RNOWRKCLI.php.
- ↑ NOAA. 2017. "Annual Climate Report." Last Modified January 10. http://w2.weather.gov/climate/index.php?wfo=eka.
- ↑ NOAA. 2017. "Preliminary Monthly Climate Data." Last Modified January 28. http://w2.weather.gov/climate/index.php?wfo=eka.
- ↑ García-Montoya, Mariana, Andrea Bocanegra-Martínez, Fabricio Nápoles-Rivera, Medardo Serna-González, José María Ponce-Ortega, and Mahmoud M. El-Halwagi. 2015. "Simultaneous design of water reusing and rainwater harvesting systems in a residential complex." Computers & Chemical Engineering 76, 104-116. Academic Search Premier, EBSCOhost (accessed January 29, 2017).
- ↑ Gould, John, and Erik Nissen-Petersen. 1999. Rainwater Catchment Systems for Domestic Supply : Design, Construction and Implementation. London: Intermediate Technology Publications.
- ↑ Boers, Th. 1994. Rainwater Harvesting in Arid and Semi-arid Zones. Wageningen, The Netherlands: International Institute for Land Reclamation and Improvement.
- ↑ 7.0 7.1 Angima, Sam D. "Harvesting Rainwater For Use in the Garden." Oregon State University Extension Service EM9101 (December 2014): 1-10. Accessed January 29, 2017. https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/em9101.pdf.
- ↑ 8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 8.10 Morales, Teresa D., and John Busch. United States Department of Agriculture. Portland, OR: Natural Resources Conservation Service, 2010. Accessed January 29, 2017. https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_046471.pdf.
- ↑ Argaw, Neway. Renewable energy water pumping systems handbook: period of performance, April 1-September 1, 2001. Golden, CO: National Renewable Energy Laboratory, 2004.