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case study for presentation PowerPoint . Please summarize the case study in world file and answer the following questions when you prepare your slides:see the file down to read case study and answer question for PowerPoint.

  1. If Mr. Parker had worked for a large corporation that had R&D through production capabilities, what processes would have been needed to manage the project? Develop a Gantt chart to map this.

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Redesigning the Ceiling Fan at the Florida Solar Energy Center A Case Study for The Mechanical Design Process Introduction Ceiling fans are an inexpensive way to cool a room making it feel 2-4oF cooler just by moving the air. The earliest electric powered fans appeared in the 1880s and the basic design of an electric motor with a set of tilted, flat blades has remained virtually unchanged until quite recently when Danny Parker set out to create a ceiling fan design to increase air moving efficiency while reducing energy consumption. The resulting fan, sold commercially as the Gossamer Wind, consumes about half the energy as previous fans while delivering more air movement. Since its introduction to the market in 2001 more than 2 million Gossamer Winds have been sold. This case study is about the invention and evolution of this new technology, basically bringing an old technology to a mature product. The Problem: Design a more efficient ceiling fan. Current ceiling fans, while providing inexpensive cooling are not very efficient. The Method: The engineers needed to: discover a new idea, refine the idea to practice, develop and test prototypes and refine the prototype to practice. Advantages/disadvantages: The companies involved were small and few formal design methods were used. This informality worked because so few people were involved and the organization relatively uncomplicated. This is a good example for the use of informal methods when the conditions are right. Background The first ceiling fans were used by the Egyptians and Romans. They were powered by their slaves. In 1882, Philip Diehl, who had previously engineered the first electric motor used on sewing machines, adapted that same technology to a ceiling fan. Since then, typical ceiling fans have been essentially unchanged, consisting of a low rpm motor with three - five flat blades attached as shown in Figure 2. Many also have a light or lights in the middle. Common ceiling fans move 60 - 70 CFM of air per watt of electricity used. They usually have multiple speeds ranging from 50 – 200 rpm. Ceiling fans are a very mature product with the only differences throughout their history being their style, number of blades, materials and finish, and lighting options. Danny Parker, a principal research scientist at the Florida Solar Energy Center (FSEC), part of University of Central Florida, was sitting on his porch one day in the early 1990s with his father-in-law, a WWII fighter pilot. They were sitting under a ceiling fan when his father-in-law noted that the blades were flat and he had never flown an airplane with a flat bladed propeller. Parker is an expert on heating and cooling, but had no aerodynamics expertise. His father-in-law’s comment started him wondering why ceiling fans had flat blades and every other propeller was airfoil shaped and twisted. Parker did some quick research and learned that flat “paddle blades” are easy to manufacture and while simple, they are not very efficient. Further, he learned that airplanes, ships and other propeller driven vehicles all have twisted, airfoil shaped blades. This has been the case since Wilbur Wright developed the propeller for the Wright Flyer in 1903. His reading told him that he could not simply use an airplane propeller for a ceiling fan. Airplane or boat propellers turn at 2000 – 3000 rpm, or faster. Ceiling fans rotate at a low rpm for safety reasons. Namely, the Underwriters Laboratories (UL), a product safety testing organization, publishes standards for all types of electrical and other products. Ceiling fans are covered in UL Standard 507 which limits the rotational rate to 50 – 200 rpm to avoid severe injuries in case someone comes in contact with a blade. Thus, the design of an efficient ceiling fan blade is more difficult than just applying airplane propeller theory to problem. None-the-less, based on his initial research, he was convinced that with the right blades, fans could be much more efficient and he convinced others at FSEC that this was an idea that could help energy conservation in Florida. Even though Parker did much reading and study on propeller technology and history, he found little to help him at the low fan speeds. What he did find was that, in the 1970s a company, AeroVironment, had designed the Gossamer Condor, the first human powered airplane to achieve controlled and sustained flight (1977) and the Gossamer Albatross, (Figure 3), the human-powered aircraft that was peddled across the English Channel in 1979. The propellers on these craft rotated more slowly than those on conventional propeller airplanes, at about 110 rpm, similar to the need for the fan. Thus, he got in touch with the designer of the Gossamer airplane propellers, Bart Hibbs, who was intrigued by the potential. Since there were no customers demanding more efficient ceiling fans or any source for research funding, this project was undertaken internally because Parker and Hibbs thought it had potential and they both worked at organizations that would allow them to tinker with new ideas with internal funding. The two organizations, the Florida Solar Energy Center and AeroVironment entered into a business agreement. Basically, they would jointly explore, at a low level, the potential of developing a ceiling fan blade using airfoil theory and see if this might lead to more efficiency. If it did, and lead to a product, they would split any royalties along an agreed percentage. Conceptual design The first question to be answered was: is there a potential to significantly increase the efficiency of a ceiling fan by using propellers rather than paddles? The explore this question, in early 1997 Hibbs used proprietary computational fluid dynamics (CFD) models that were specifically designed for very low speed propeller analysis. Hibbs developed eight fan blade designs using different airfoils and blade shapes and twist. The leading candidate for the ceiling fan design is shown in Figure 4. The nearly vertical section is near the root of the blade with the chord (leading edge to trailing edge distance) getting smaller and more horizontal toward the tip. Comparing this to a flat, paddle type blade of constant chord (Fig 2), the difference is dramatic. What is even more important, Hibbs’ models showed that this blade could move twice the air for the same power, a 100% increase in efficiency. Prototype Development and Testing The concepts generated by AeroVironment were evaluated by FSEC and one chosen for testing based on promising theoretical performance. Research engineer Jeff Sonne, at FSEC, was an experienced wood-worker and carefully crafted a set of balsa wood blades while Parker developed a ceiling fan test facility. The facility allowed measuring the total air flow, the airflow at different radii and the sound level. The test rig was made so that the tip angle could be adjusted as the CFD simulations showed optimal airflow at anywhere between 4 and 6.5 degrees at the tips for a 52” diameter fan (a typical ceiling fan diameter). The test blades had a chord of approximately 6.5" wide at the blade root tapering to just 2.5" at the rounded tip. The blades were 20.5" long with an estimated surface area of 93 square inches. Unlike the paddle bladed ceiling fans, the propellers for the new design were highly twisted and tapered airfoils. Testing was done by comparing the new design, called the CF-1 (“Ceiling Fan #1”), to three conventional ceiling fans: Emerson "Northwind" CF705, a low cost model - $70, representing a very large part of the current ceiling fan market. It consists of a fan with four flat blades and an inexpensive 50 watt shaded pole induction motor. The flat blades had a nominal angle of 12.5 degree, a chord of 5" at the blade root and 5.5" at the tip. They were 20 inches long, made of painted wood and each had a measured weight of 329 grams with mounting hardware. Emerson "Premium" CF4852, a more expensive (>$400) 5-bladed, 50” diameter fan which represented the upper end market designed to move more air. Advertising claimed 5595 cfm at 100 watts resulting in 56 cfm/watt. Hunter "Summer Breeze" rated as one of the best ceiling fans in terms of air moving efficiency by Consumer Reports. The flat ceiling fan blades were similar to the Emerson models. The prototype CF-1 fan used the same motor as the Emerson CF705 fan with the only difference being the new blades. Testing was primarily done at two speeds, low and high speeds. Low speed varied by the fan model and motor configuration between 40 and 70 rpm). The measured air flow in meters/second for the four differing fans at low speed operation over the six foot region comprising the measurement area is shown in Figure 5. This data is shown in summary form in Table 1. The FSEC/AeroVironment fan exhibited clearly superior performance to the paddle blade fans. The Hunter fan provides the most competitive comparable performance. Since the Emerson CF705 and the CF-1 use the same motor it is possible to see the impact of the improved blades alone by comparing their performance results. Table 1 Comparative fan performance and efficiency at high speed Value Emerson CF705 Emerson CF4852 CFM Watts CFM/Watt 3110 50.2 61.9 6057 93.1 65.1 Hunter Summer Breeze 5339 74.8 71.4 FSEC/ Aerovironment CF-1 6471 49.6 130.5 The improvement due to the advanced fan blade shown in Table 1 was particularly dramatic with an efficiency (cfm/watt) improvement of nearly 100% over the CF705, the fan with exactly the same motor. The typical airflow distribution is as shown in Figure 6. This clearly illustrates the increased volume of air moved along with a slightly greater radius of perceptible air flow below the disk of motion. Finally, the test fan was noticeably quieter than the other fans. The Hunter “Summer Breeze” produced 5.7db over the ambient background noise (57db) while the CF-1 produced a sound pressure level of only 0.3db. This 5.4db difference translates into an intensity difference of a factor of 3.5. Since inefficiency is energy that is translated into noise, this is not surprising. These results confirmed what Parker had suspected, there was much efficiency to be gained in the design of the blades on a ceiling fan. The Patent In 1998 Parker and his partners at AeroVironment applied for a patent titled “High Efficiency Ceiling Fan”. This was awarded in 2000 as patent number 6,039,541. The front page of the patent is shown in Figure 7. The 16 claims are all built around the first one (Figure 8) as is typical in most patents. There are three major ceiling fan blade features claimed: blade twist, blade thickness taper, and chord taper. Product development Neither FSEC nor AeroVironment were in the business of producing consumer products. Thus, they needed a third partner to manufacture and market fans based on the new design. They wrote a prospectus which they sent to companies who produced ceiling fans. After negotiations with a number of manufacturers, a business deal was struck with King of Fans, one of the leading producers of home comfort products worldwide. While their name is not well known, they produce over 4 million units a year, selling fans through Home Depot, Lowes and others under a wide variety of names, most notably; Hampton Bay. King of Fans is a family owned Taiwan company with a small group of engineers in Taichung. These engineers developed a set of specifications needed to turn the CF-1 into a product. They were: A significant increase in efficiency. (The test fan produced nearly 100% improvement but they knew this would be lowered in meeting other specifications) Meet Energy Star airflow efficiency requirement of 75 cfm/watt at high speed Must operate effectively from 50 rpm to 200 rpm Must work in pulling air up and pushing it down (forward and reverse). The need to rotate in both directions required additional modification to the fan-blade design. The test airfoil was designed to only move air in one direction. No sharp edges (UL requires that no edge of a fan blade be thinner than 3.175 mm (1/8 inch) diameter. The test blades had sharp trailing edges. Quietness of operation – at least as good as or better than current fans. Provide light o At least 1500 lumens o High efficiency o Long life bulb(s) o Easy to replace All features should speak of quality All features should speak of efficiency Further, they saw this product as an opportunity to add a remote control device that they had been developing for a number of years. This device should meet the following specifications: At least 3 speeds Direction control Light control In addition to the specifications, a key consideration of the product was its overall appearance. King of Fans felt that the design that was optimized for airflow and airflow efficiency was too radical in form to generate the level of customer appeal (i.e. sales) necessary at mass retail, so they sacrificed some performance in exchange for a more mainstream appearance. They worked over an eight month period to find the right balance of form and function, a product that could meet the specifications and was visually appealing. The highlights of the resulting product and the effort are described below. The Blades The blades on virtually all previous ceiling fans were cut from flat material. Those on the test model were laboriously hand built over a couple of month period. Due to the complexity of the shape, the only reasonable option for production was injection molding. ABS was selected as it is inexpensive and easy to injection mold. To meet the requirements to produce flow in both directions and have no sharp edges, the trailing edge of the blade had to be rounded. Further, the area near the root had to be flattened (less angle of incidence) to keep the mold from being overly thick, increasing the manufacturing costs. These compromises to meet safety concerns and the manufacturing reality reduced the increase in efficiency to 40%. The production fans still move 6,779 cfm with 64 watts on high speed resulting in 105 cfm/watt. This is still a dramatic increase over existing fans, and the Gossamer Wind exceeds the Energy Star airflow efficiency requirement of 75 cfm/watt at high speed by 40%. Energy Efficient Light Kit Since this product was to be marketed as eco-friendly and had such a high increase in air moving capability, the lighting efficiency also needed to be addressed. Conventional fans use either a 100 W linear halogen lamp or three or more 40 W incandescent bulbs. These 100-120 watts lights more than doubled the energy usage of the fan itself (64 watts). The bulb chosen is to address this problem was a circular compact fluorescent bulb. This uses 20 watts and provides about the same lumens as the halogen or 3- 40 watt incandescent bulbs (1450 lumens), although with a somewhat softer illumination. Equally important is the life expectancy: the compact fluorescent lamp has a MTBF of 12,000 hours versus 2,000 hours for the 100 W halogen lamp. Thus, the CFL lamp will likely not need changing over the life of the fan. Conclusions The resulting product, manufactured by Hampton Bay, has been commercially available throughout the United States since 2001. The new blade design referred to as Gossamer Wind provides 40 percent higher airflows without increasing energy use. It is one best-selling ceiling fan designs in the market place and, in its thirteenth year, one of the longest offered. It was also one of the first ceiling fans to be Energy Star listed. Since the introduction of the Gossamer Wind other manufacturers have developed similar fans and there is on-going litigation regarding patent infringement within the ceiling fan market. Links This case study borrowed heavily from Development of an Enhanced Ceiling Fan: An Engineering Design Case Study Highlighting Health, Safety and the Environment a case study developed by Marc Rosen, Professor at the University of Ontario, Institute of Technology, Jan 2009. US Patent 6039541, High Efficiency Ceiling Fan, Inventors D. S. Parker, G.H. Su, B. D. Hibbs, 2000 Development of a high efficiency Ceiling Fan “The Gossamer Wind”, D.S. Parker, M. P. Callahan, J. K. Sonne and G.H. Su, Florida Solar Energy Center (FSEC), FSECV-CR-1059-99, 1999. Performance and Applications of Gossamer Wind™ Solar Powered Ceiling Fans, M. Lubliner, J. Douglass, D. S. Parker, D Chasar, FSEC-PF-411-04, 2004. http://www.gossamerwind.com/content/gossamer-windward-iii-white-0 http://www.fsec.ucf.edu/en/ Florida Solar Energy Center http://www.avinc.com/ Energy Star Program Requirements for Residential Ceiling Fans: Partner Commitments http://www.energystar.gov/ia/partners/prod_development/revisions/downloads/cei l_fans/Final_Ceiling_Fans_Prog_Req_Version_2.0.pdf Author This case study was written by David G. Ullman, Emeritus Professor of Mechanical Design from Oregon State University and author of The Mechanical Engineering Process, 5th edition, McGraw Hill. He has been a designer of transportation and medical systems and holds five patents. More details on Professor Ullman can be found at www.davidullman.com. In writing this case study he was assisted by Danny
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