(point focus array) Introduction to Engineering Instructor: Dr. Khalil Sharif. NWACC EMPACTS Project

Transcription

1 (point focus array) Introduction to Engineering Instructor: Dr. Khalil Sharif Project team: Eric Brewer, Julio Ayala, and Chase Cavalier NWACC EMPACTS Project

2 Quick Lesson Shape of a parabolic concentrator (point focus array) The shape, or contour, of a parabolic dish is determined by the equation: Y = X²/4a, where a is the focal length from the xy axis or (0,0). In this case the focal length will be 10 inches from the axis giving the equation: Y = X²/40 In order to determine the angle of incidence, the angle the sun s rays reflect off of the dish, we have to first find the slope of the dish at any given point. We do this by taking the derivative of the equation Y = X²/40 to obtain: Y = X/20. Now knowing that the derivative is equal to or the same as tan(θ) allows us to re-write the equation as: θ = arctan(x/20). A. B. The angle θ is the angle of incidence. The angle of incidence is defined as the angle measured from the normal or a perpendicular line to the slope ie. (tan (θ)). The tangent line and the normal line are shown in B.

3 Quick Lesson (Cont.) Finally the refraction or total angel reflected off of the parabolic surface is defined to be: 2(θi = arctan(x/20)) This simply means we will double the angle of incidence found with the equation: θ = arctan(x/20). Now lets show the proof. Without breaking out a compass, angle finder, or working with a sheet of paper we will simply show the clearly visible proof using the final equation. Let us plug in a value of X = 20 into the equation: 2θ = 2arctan(X/20) = 2arctan(20/20) = 2arctan(1) = 2(45) = 90. It is clearly visible in A. that the suns ray that strikes the dish at X = 20 refracts at an angle of 90 degrees striking the concentrator at its focal point, Y = 10.

4 Introduction Our project is a solar concentrator, or point focus array. We will use a parabolic dish to focus a large amount of solar radiation into a concentrated area allowing us to make use of the high heat yield to convert steam into usable energy. Original concept

5 Project Overview Because of the technicality of the project we have chosen, the team decided to use as many ready made products for construction as possible. The parabolic dish is used to create a large surface area that will collect the largest amount of solar radiation possible for refraction. A satellite dish for T.V. or internet is repurposed for this application. The reflective surface is used to redirect the large amount of incoming rays, hitting the dish from the sun, in to a small concentrated area. UV reflective window film is utilized because of its high refractive qualities. An extension must be added to the existing arm which will allow us to place an object at the precise location of the most concentrated point of refraction, also known as the focal point. For this objective we used one inch angled aluminum.

6 Project Overview (cont.) In order to collect the solar radiation, at the focal point, a pressurized canister is used so that the bottom of the canister is heated to a temperature suitable for water to come to a boil. (212 degrees F.) The pressure created in the container by the boiling water must be rerouted to a mechanical device to convert the pressure into kinetic energy. We utilized copper tubing with pressurized fittings for this. Finally we need a kinetic component such as a piston and fly wheel or fan to convert thermal energy to kinetic energy. Our max temp F.

7 Curriculum Our project covers a wide range of physical sciences and mathematics: We have used physics in the process of understanding the reflective and refractive qualities associated with a solar concentrator. The use of trigonometry, geometry and physics is key to calculating the dimensions and other precise concepts that must be utilized for this project. We must use knowledge of heat and pressure to use the product of the solar radiation and water to produce usable steam. Turning compression into a usable kinetic energy by way of a piston is also a strong physical science objective.

8 Technology Used Software: Our team used a variety of software for our project. Microsoft publisher Team viewer Microsoft PowerPoint 2003 Microsoft paint Picasa 3

9 Technology Used (cont.) Hardware: Drills Self tapping screws Satellite dish Propane container Miter saw Hair dryer (our heat gun) Solar UV protective film Angled aluminum Metal lathe (Chase Cavelier) Copper tubing Compression fittings Satellite dish tripod 3M industrial adhesive TI-84 Plus Calculator

10 Technology Used (cont.) This piston, housing, shafts, cam wheel, and other components were created by Chase Cavelier at his home on his metal lathe. Great Work Chase. All these components can be considered technologies used.

11 Methods of the Project At the teams first meeting we decided on which of several ways we could approach the project. Thanks for the final decision Dr. Sharif. As stated before we decided to use as many pre-made products as possible to cut down on manufacturing the final product. The team came up with a rough sketch of what needed to be done to make the project happen. Based on our sketch we started a components list for materials we would need, both ready-made and loose. We voted on a team leader and began to divide up parts to acquire and separate project responsibilities. Over the next few meetings the team obtained some of the main components for the concentrator. We created a list of store hardware and parts that were not obtainable through personal or general means.

12 Methods of the Project (cont.) The team placed our order and waited until the store components were ready for us to pick up. After the main pieces of the dish were assembled we did an initial test, only checking the heat at the focal point (300 plus degrees F). This was very exciting. Two meetings were spent completing the main bulk of the solar concentrator and making adjustments to the original design. Finally after the whole concentrator was put together, minus the piston, we tested to see that our machine could do its job.

13 Project Results On a clear sunny day for final testing, to determine if the solar concentrator focused solar radiation, heated the propane container, and boiled the water inside, the team found patience. After a two hour wait the concentrator was neither producing a reading on the pressure gauge or heating the water to a boil. Based on some knowledge of thermal dynamics, we concluded that the small concentration of solar radiation, while extremely hot, could not surpass the cooling affect of the ambient temperature on the remaining surface area of the container that was not being heated. At this point in the project the team consensus is to replace the propane container with a container of smaller diameter and to add some type of insulation. This should, in theory, reduce the amount of cooling created by the remaining unheated surface area. Testing is necessary.

14 References and Thanks Dr. Khalil Sharif Instructor and project support. C. Dianne Phillips Head of EMPACTS, Program facilitator Calculation of the Focal Length of an Offset Satellite Dish Antenna, Equation of a Parabolic dish. Sears. Semansky. Young. Freedman.University Physics with Modern Physics 13 th Edition. Pearson. text General information, Refraction of a lens. Chase Cavelier manufacturing of piston, components, and threaded cap for canister. Steam Piston Design.