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Journal articles on the topic "Heather headley"
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KITLV, Redactie. "Book reviews." Bijdragen tot de taal-, land- en volkenkunde / Journal of the Humanities and Social Sciences of Southeast Asia 161, no. 2 (2009): 350–96. http://dx.doi.org/10.1163/22134379-90003712.
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Peter Borschberg (ed.), Iberians in the Singapore-Melaka area and adjacent regions (16th to 18th century) (Syed Muhd Khairudin Aljunied) Katharine L. Wiegele, Investing in miracles; El Shaddai and the transformation of popular Catholicism in the Philippines (Greg Bankoff) Jean Gelman Taylor, Indonesia; Peoples and histories (Peter Boomgaard) Clive Moore, New Guinea; Crossing boundaries and history (Harold Brookfield) Nathan Porath, When the bird flies; Shamanic therapy and the maintenance of worldly boundaries among an indigenous people of Riau (Sumatra) (Cynthia Chou and Martin Platt) Paul van der Grijp, Identity and development; Tongan culture, agriculture, and the perenniality of the gift (H.J.M. Claessen) Tim Bunnell, Malaysia, modernity and the multimedia super corridor; A critical geography of intelligent landscapes (Ben Derudder) L. Fontijne, Guardians of the land in Kelimado; Louis Fontijne’s study of a colonial district in eastern Indonesia (Maribeth Erb) Karl-Heinz Golzio, Geschichte Kambodschas; Das Land der Khmer von Angkor bis zur Gegenwart (Volker Grabowsky) Emmanuel Poisson, Mandarins et subalternes au nord du Viêt Nam; Une bureaucracie à l’épreuve (1820-1918) (Martin Grossheim) Generale Missiven van Gouverneurs-Generaal en Raden aan Heren XVII der Verenigde Oostindische Compagnie, Volume 10, 1737-1743 (Gerrit Knaap) Aris Ananta and Evi Nurvidya Arifin (eds), International migration in Southeast Asia (Santo Koesoebjono) Vladimir Braginsky, The comparative study of traditional Asian literatures; From reflective traditionalism to neo-traditionalism (G.L. Koster) Fiona Kerlogue (ed.), Performing objects; Museums, material culture and performance in Southeast Asia (Jennifer Lindsay) Th.C. van der Meij, Puspakrema; A Javanese romance from Lombok (Julian Millie) Robyn Maxwell, Sari to sarong; Five hundred years of Indian and Indonesian textile exchange -- Jasleen Dhamija, Woven magic; The affinity between Indian and Indonesian textiles (Sandra Niessen) David Bourchier and Vedi R. Hadiz (eds), Indonesian politics and society; A reader (Seije Slager) Howard Dick, Vincent J.H. Houben, J. Thomas Lindblad and Thee Kian Wie (eds), The emergence of a national economy; An economic history of Indonesia, 1800-2000 (Heather Sutherland) Roderich Ptak, China, the Portuguese and the Nanyang; Oceans and routes, regions and trade (c. 1000-1600) (Heather Sutherland) Stephen C. Headley, Durga’s Mosque; Cosmology, conversion and community in Central Javanese Islam (Robert Wessing)
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Avdeev, A. A., A. S. Shamarokov, and L. N. Fal’kovskii. "Header-platen high-pressure heaters." Thermal Engineering 56, no. 2 (2009): 147–52. http://dx.doi.org/10.1134/s0040601509020104.
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Raben, David, and Adam Raben. "A Two-Headed Heated Debate." International Journal of Radiation Oncology*Biology*Physics 111, no. 2 (2021): 310. http://dx.doi.org/10.1016/j.ijrobp.2018.08.041.
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Venkatesh, R., and W. Christraj. "Performance Analysis of Solar Water Heater in Multipurpose Solar Heating System." Applied Mechanics and Materials 592-594 (July 2014): 1706–13. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.1706.
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Of all the renewable sources of energy available, solar thermal energy is the most abundant one and is available in both direct as well as indirect forms. In order to increase the thermal performance of solar collectors, the multipurpose solar collectors were investigated experimentally by the storage tank of the conventional solar water collector is modified as riser tubes and header. It is fitted in the bottom of the solar air heater as an absorber in the normal air heater. The thermal performance of thermosyphon flat plate solar water heater was investigated on both summer and winter seasons. The maximum daily average of 72.05%, 0.0316 kg/sm2and 0.873 m/s were recorded for the relative humidity, mass flow rate and wind speed at summer season respectively. Corresponding figure at for winter was 19.5 % 0.0295 kg/sm2and 0.722 m/s respectively. A minimum daily average of 11.23% and 0.384 m/s for the relative humidity and wind speed respectively. These results show that the mass flow rate obtained was a function of solar radiation and relative humidity. The less humid the ambient air becomes, the higher the heat gained by the system hence higher water flow rate. The maximum value of relative humidity obtained is due to low solar radiation on winter season. The heat removal factor (FR) and collector efficiency factor (Fo) were found to be higher for Multipurpose solar water heater as compared to conventional solar water heaters for summer as well as winter season. These factors for Multipurpose solar water heater were more during summer and winter.
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Yang, Jichun, Qingyang Jiang, Jingxin Hou, and Chenglong Luo. "A Study on Thermal Performance of a Novel All-Glass Evacuated Tube Solar Collector Manifold Header with an Inserted Tube." International Journal of Photoenergy 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/409517.
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A novel all-glass evacuated tube collector manifold header with an inserted tube is proposed in this paper which makes water in all-glass evacuated solar collector tube be forced circulated to improve the performance of solar collector. And a dynamic numerical model was presented for the novel all-glass evacuated tube collector manifold header water heater system. Also, a test rig was built for model validation and comparison with traditional all-glass evacuated tube collector. The experiment results show that the efficiency of solar water heater with a novel collector manifold header is higher than traditional all-glass evacuated tube collector by about 5% and the heat transfer model of water heater system is valid. Based on the model, the relationship between the average temperature of water tank and inserted tube diameter (water mass flow) has been studied. The results show that the optimized diameter of inserted tube is 32 mm for the inner glass with the diameter of 47 mm and the water flow mass should be less than 1.6 Kg/s.
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Sivakumar, P., W. Christ Raj, N. Jaya Malathi, and S. Balakrishnan. "Performance Analysis of Flat Plate Solar Water Heater by Changing the Heat Pipe Material." Advanced Materials Research 768 (September 2013): 64–69. http://dx.doi.org/10.4028/www.scientific.net/amr.768.64.
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Heating of water for domestic purpose is simple and effective way of utilizing solar energy. Though the initial cost of solar water heating system is high, the maintenance cost and zero green energy cost. To overcome the problem of high initial cost, this paper suggests utilizing alternative material with very good absorbing efficiency material instead of copper. The stainless steel tube coated with epoxy-polyether and aluminium with copper oxide coating are used as a header and riser tube material instead of copper which is in practice now-a-days. This paper introduces a new heating system which has flat plate collector of effective performance at low cost even though stainless steel and aluminium has low thermal conductivity. Experiments have been conducted by using copper, stainless steel and aluminium tubes as header and riser tubes. The result shows that copper, aluminium and stainless bestow the same performance. Also the cost of stainless tube with epoxy-polyether and aluminium with copper oxide are less than that of copper tube.
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Seo, Hyukki, Kyeongmo Hwang, and Cheongyeol Choi. "Numerical Case Study on the LDIE Degradation Occurred in the Vent Header of a High Pressure Feedwater Heater." World Journal of Nuclear Science and Technology 04, no. 01 (2014): 26–32. http://dx.doi.org/10.4236/wjnst.2014.41005.
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Manning, R. "Evaluation of the Western Australian queen bee breeding program." Australian Journal of Experimental Agriculture 36, no. 4 (1996): 513. http://dx.doi.org/10.1071/ea9960513.
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Agriculture Western Australia's former Queen Bee Breeding Program (QBBP) was successful in significantly raising the productivity of honey bee colonies for those beekeepers who regularly purchased queen bees from the program. The increased productivity was measured through honey production. Over 2 nectar flows, colonies headed by queens purchased from the breeding program (group 2) showed a 35% increase in honey production over unselected colonies (group 1-not purchased from the QBBP). Over individual nectar flows, colonies headed by queens purchased from the breeding program showed a 22% increase in honey production from a Eucalyptus calophylla nectar flow, and for a second protracted winter nectar flow from coastal heath they also produced 46% more honey than unselected queen bees. Honey production (kg/colony.day) from Eucalyptus calophylla was 0.95 and 1.13 kg for groups 1 and 2, respectively. Honey production from the coastal heath was 0.27 and 0.4 kg/colony.day for groups 1 and 2, respectively. Results were projected for 1 year and scaled up to represent a commercial apiary of 400 colonies. According to estimates from the data, group 2 beekeepers should have benefited from the QBBP by being able to produce 24 t of honey from their apiaries, valued in excess of $A32 000, more than group 1 beekeepers.
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Daga, R., G. Bandyopadhyay, M. K. Samal, B. K. Dutta, and A. K. Mohindru. "Consumed creep life fraction assessment of critical locations of an in-service super heater outlet header under surveillance programme." Transactions of the Indian Institute of Metals 63, no. 2-3 (2010): 423–29. http://dx.doi.org/10.1007/s12666-010-0058-1.
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Chugh, V., R. Parmar, J. Schut, J. Sherin, H. Xie, and D. Zobin. "Value Addition Initiative For CANDU® Reactor Operation Performance." AECL Nuclear Review 2, no. 1 (2013): 99–108. http://dx.doi.org/10.12943/anr.2013.00009.
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Recently, AMEC NSS initiated projects for CANDU® station performance engineering with potentially high returns for the utilities. This paper discusses three initiatives. Firstly, optimization of instrument calibration interval from 1 to 3 years will reduce time commitments on the maintenance resources on top of financial savings ~$3,500 per instrument. Secondly, reactor thermal power uncertainty assessment shows the level of operation which is believed to have an over-conservative margin that can be used to increase power by up to 0.75%. Finally, as an alternative means for controlling Reactor Inlet Header Temperature (RIHT), physical modifications to the High Pressure (HP) feedwater heaters can be useful for partially recovering RIHT resulting in increased production by 10-12 MWe.
Dissertations / Theses on the topic "Heather headley"
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Owens, Kelli. "The Oppression and Sexism of African-American Women: Then and Now: Substantial Contributions to the History of Musical Theatre." Honors in the Major Thesis, University of Central Florida, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1631.
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A wise Martin Luther King Jr. once said, "Freedom is never given by the oppressor; it must be demanded by the oppressed (King 1)." For as long as men and women have shared the planet, sexism has been a universal issue in civilization. In a social justice context, American society has found ways to oppress people for centuries. The Oxford Dictionary defines sexism as a "prejudice, stereotyping, or discrimination, typically against women, on the basis of sex ("sexism")." Voting rights in America were established in 1790, but it took years of petitioning at various women's rights conventions before the Nineteenth Amendment to the United States Constitution stating "the right of citizens of the United States to vote shall not be denied or abridged by the United States or by any State on account of sex" was passed in 1920 ("Nineteenth Amendment"). Traditionally, men were supposed to be the strong, decisive, driven, courageous, money-making breed, while women were expected to be the nurturing, affectionate, weak subordinates. Today, we find men and women working in careers previously linked with sexism; men as nurses and teachers, women as CEOs and factory workers. Statistics show that today there are an increasing number of women providing the financial support in their families. As with sexism, people also have been oppressed by racism for centuries. According to The Oxford Dictionary, racism is defined as a "prejudice, discrimination, or antagonism directed against someone of a different race based on the belief that one's own race is superior ("racism")." It has been argued that African Americans have been one of the most oppressed groups in America. Even after they were emancipated in 1865, it was nearly one hundred years later that their rights were protected with the Civil Rights Act of 1964. Before the act's passing, African Americans were denied equal education, employment, housing property, and a political voice. My interest in this topic was peaked right around the same time I became interested in performing on the musical theatre stage. I got my start in local community theatres, and up until college, was the only African American cast in the productions. I started playing multiple ensemble roles per show, and throughout the years advanced myself to "supporting character" but never the lead. Admittedly, there were times when I wasn't as talented as the women who snagged the leading roles, but many a time when I was just as talented or more qualified for the role, it went to another woman - most times of Caucasian descent. What did they have that I didn’t have? When I got accepted into The University of Central Florida as a BFA Musical Theatre student, I auditioned for the plays and musicals every semester, and each season I began to see the same patterns of who was cast for each show. Roles I thought I would get often went to White actors. I felt victimized in this modern-day example of racism. But racism goes beyond black and White. Internal racism between the light-skinned and dark-skinned African American women I was competing with became a factor as well. There were many times when an audition notice called for an African American woman; however, an unsettling trend became very apparent to me; if the casting description was for a maid, or something of that nature, larger, dark-skinned women would get the majority of the callbacks, which would lead to them getting cast. On the flip side, if an audition notice called for an African American ingénue type, more of the slimmer, lighter-skinned women were called back and later cast. Has American society cast a racial stigma for African American beauty?<br>B.F.A.<br>Bachelors<br>Theatre<br>Arts and Humanities<br>Musical Theatre
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Allie, Mohammed Nazier. "Thermal modelling of feedwater heaters." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20348.
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Manufacturers of feedwater heaters (FWHs) are obliged to disclose a specification sheet to the client that describes their FWH design. However, the client is unable to verify the performance of this FWH design without comparing it to the results that are predicted by a thermal model. An additional limitation is that the manufacturer will only disclose the minimum number of design parameters. The purpose of this study was to develop a thermal model that can predict the performance of a FWH. The model requires the minimum design input data to predict the performance parameters that may be compared to values predicted by the vendor. A FWH in a regenerative water-steam Rankine cycle achieves heat transfer to the feedwater by condensing steam on the shell side. This is called a single zone FWH. The tube plate type FWH is the most common type of FWH referenced in literature but the following variations may exist: • The Eskom fleet consist of both tube plate and header type FWHs. • FWHs may be orientated vertically or horizontally. Internal shrouded regions, that define it as a 2 or 3 zone FWH, may be present in the FWH. The length of the drains cooler (DC) zone may either be identified as long or short. A general model was required to capture all these design variations. Plant visits were arranged with engineers at several power stations to obtain the minimum input data and to confirm that these FWH design variations existed within the Eskom fleet. The model was based on existing tube plate models found in literature. It was then extended to accommodate the FWH variations mentioned above. A further improvement was made by including an additional heat transfer sub-zone that removes excess superheat in the condensing (COND) zone. The vendor does not disclose the correlations used to predict the film heat transfer coefficients (h) in their design. Therefore, the user is granted the option of selecting a correlation from a list of popular correlations, specific to a heat transfer mode. Note that the uncertainty associated with this thermal model is affected by the uncertainty of each correlation selected in the model.
Book chapters on the topic "Heather headley"
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Wall, Stephen. "Second Thoughts, 1961–1969." In Reluctant European. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198840671.003.0004.
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Future Prime Minister Edward Heath headed the British team that negotiated for British accession to the EEC. Reconciling UK Commonwealth interests with the established EEC rules, especially on agriculture, was problematic. Successive meetings between Prime Minister Macmillan and President de Gaulle made little headway in overcoming de Gaulle’s resistance to UK membership. In January 1963, de Gaulle vetoed the UK application. When the Conservatives lost office in the 1964 General Election, Prime Minister Wilson gradually came to the same view as Macmillan. The Labour government renewed the British application but, once again, in 1967, de Gaulle vetoed it. Only with de Gaulle’s resignation in 1969 was the prospect of membership reopened.
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Mokhtar, Ainul Akmar, and Muhammad Kamil Kamarul Bahrin. "Failure Analysis of High Pressure High Temperature Super- Heater Outlet Header Tube in Heat Recovery Steam Generator." In Failure Analysis and Prevention. InTech, 2017. http://dx.doi.org/10.5772/intechopen.72116.
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Milam, Erika Lorraine. "The Old Determinism." In Creatures of Cain. Princeton University Press, 2018. http://dx.doi.org/10.23943/princeton/9780691181882.003.0015.
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This chapter explores the increasingly heated debates over sociobiology. These debates within academic circles had polarized into arguments over nature versus nurture, biology versus culture, as the primary determinants of why humans behave the way we do. Scientists on both sides of the issue accused the other of allowing politics to interfere with clear-headed scientific analysis. Sociobiology's critics mobilized out of a concern that sociobiologists were using their authority as scientists to advance ideas and concepts that at best lacked rigorous proof and at worst reframed social policy in the language of natural order. That sociobiologists did not intend for their theories to be used as the basis for social policy was irrelevant. If the not-so-Cold War had taught scientists anything, sociobiologists' detractors argued, it should have been that they had a moral obligation to choose their research topics carefully. This precept extended to conflicts at home, where courts and politicians used biological and anthropological research to prop up discriminatory social policies, they suggested, as well as abroad, where the efforts of scientists in creating bombs and other weapons of war were deployed to devastating effect.
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Jensz, Felicity. "‘Poor heathens’, ‘Cone-headed natives’ and ‘Good water’: the production of knowledge of the interior of Australia through German texts from around the 1860s." In Remembering German-Australian Colonial Entanglements. Routledge, 2020. http://dx.doi.org/10.4324/9780367822248-8.
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Copeland, Jack, and Catherine Caughey. "Mr Newman’s Section." In Colossus. Oxford University Press, 2006. http://dx.doi.org/10.1093/oso/9780192840554.003.0022.
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When Turing arrived at Bletchley Park, the day after Chamberlain’s announcement of war with Germany, he joined Dilly Knox’s Research Section. The job of the Research Section was to study enemy ciphers and operating procedures, and to devise methods of attack. The techniques invented by this high-powered think-tank were then handed over to other sections where they were used operationally against the enemy traffic. In 1939, Enigma was the focus of research. By the time Tutte joined the Research Section, in mid-1941, Captain Gerry Morgan headed it. Tunny soon became the leading problem. Thanks to Tutte, the Research Section broke the Tunny machine in January 1942, and in July read up-to-date traffic for the first time. Tunny could now be tackled operationally, and a Tunny-breaking section was immediately set up under Major Ralph Tester. Several members of the Research Section moved over to the ‘Testery’. Armed with Turingery and other hand methods, the Testery read nearly every message from July to October 1942—thanks to the insecure 12-letter indicator system (see Chapter 3). In October, however, the 12-letter indicators were replaced by QEP numbers and the Testery, now completely reliant on depths, fell on leaner times (see Chapter 5). The Research Section renewed its efforts against Tunny, looking for a means of wheel setting that did not depend on depths. With the invention of Tutte’s method, Newman was given the job of developing the necessary machinery, and when the Heath Robinson was delivered in June 1943 the ‘Newmanry’ became a separate section. From December 1943 the Newmanry would be responsible for breaking and setting the chi-wheels, and the Testery for breaking and setting the remaining wheels manually. The two sections worked hand-in-glove. Initially Newman’s staff consisted of one cryptographer (Michie), two engineers, and 16 Wrens. Soon a second cryptographer arrived (Good), and after three months of experimentation, two or three messages were being set each week. ‘Cryptographers’, ‘engineers’, and ‘Wrens’ remained the principal staffing categories of the Newmanry throughout the war. By May 1945, there were 26 cryptographers, 28 engineers, and 273 Wrens. During the period June 1943 to July 1944, two Americans joined the cryptographic staff of the Newmanry.
Conference papers on the topic "Heather headley"
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Robson, Fred L., John D. Ruby, and Daniel J. Seery. "Integration of High Performance Power Systems (HIPPS) Into Vision 21." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0027.
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The U.S. Department of Energy/Federal Energy Technology Center (DOE/FETC)-sponsored High Performance Power Systems (HIPPS) program headed by United Technologies Research Center has identified coal-based combined-cycle power systems using advanced technology gas turbines that could operate at efficiencies approaching 55% (HHV). The HIPPS uses a High Temperature Advanced Furnace (HITAF) to preheat combustion turbine air. The HITAF’s metallic air heaters include a radiator section located in the furnace slagging zone and a convection section located in the downstream portion. The compressor discharge air is heated to 925 C – 1150 C. Additional heat for the turbine, if required in the cycle, is added by special low-NOx gas-fired combustors. The HITAF design has been successfully tested at the desired temperatures for short durations at the Energy and Environmental Research Center, Grand Forks, ND, with tests continuing to expand the systems experience and capabilities. The HIPPS concept with its HITAF advanced air heater are valuable technology candidates for integration into Vision 21, the DoE’s evolving plan to utilize coal and other fossil fuels in energy complexes producing power, chemicals, process heat and other byproducts. For example, the HIPPS would be combined with high temperature fuel cells, e.g., the solid oxide fuel cell (SOFC), resulting in power systems having overall electrical efficiencies greater than 60% (HHV) with 50% or more of the energy input from coal. These power plants would have near zero emissions with a goal for power costs 10% below current coal-fired systems. Emissions of CO2, an important greenhouse gas, will be drastically reduced by the higher efficiencies of HIPPS cycles. Very important from a power and coproduction market viewpoint, HIPPS can be an attractive repowering technology. This will allow Vision 21 technology to be used in those plants that seek to continue using coal and other alternative solid fuels to capture the economic benefits of their low energy costs. Here, HIPPS adds high efficiency; increased capacity; load following and dispatching flexibility, as well as important environmental benefits to sites having existing fuel and transmission infrastructure.
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Li, Bing, Preston Tang, Khurram Khan, and Akash Bhatia. "Design Modification to Mitigate the Reactor Inner Zone Inlet Header Temperature in a CANDU Reactor." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65096.
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The Reactor Inner Zone Inlet Header (RIZIH) temperatures have raised more rapidly in the CANDU units in general, compared to the original aging predictions. The RIZIH high temperature alarms are required to be monitored to prevent operation outside the safe operating envelope as supported by the safety analysis. To prevent RIZIH temperature alarms, increasing RIZIH temperatures are being mitigated through changes in unit operating conditions which have caused power derates (as low as 87% Full Power) and a loss of revenue. In order to address the above concerns, a CANDU utility has initiated a study to evaluate multiple design alternatives and develop the best design option to improve RIZIH temperatures control. Seven design alternatives were assessed to a sufficient level based on their risk, suitability, economics, and effectiveness in managing RIZIH temperature with minimum system level impacts to interfacing systems. The study concluded that the external feedwater bypass of High Pressure Heater is the preferred option.
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Harling, Henry E. "Design of an Automatic Waterhammer Prevention System." In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57405.
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The Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 96-06 [1] which required utilities to evaluate the potential for waterhammers in cooling water systems serving containment following a Loss of Offsite Power (LOOP) concurrent with a Loss of Coolant Accident (LOCA) or Main Steam Line Break (MSLB). At Duke’s Oconee Nuclear Station, analysis and system testing in response to GL 96-06 concluded that waterhammers occur in the Low Pressure Service Water (LPSW) system during all LOOP events. Column Closure Waterhammers (CCWH) occur when the LPSW pumps restart following a LOOP and rapidly close vapor voids within the system, specifically, in the Reactor Building Cooling Unit (RBCU) and Reactor Coolant Pump (RCP) motor piping. Condensation Induced Waterhammers (CIWH) occur when heated steam voids interact with sub-cooled water in long horizontal piping sections, specifically in the RBCU and Reactor Building Auxiliary Coolers (RBAC) piping. These waterhammers were not expected to result in pipe failure, but resulted in piping code allowable stresses being exceeded. Piping code compliance was achieved by installing modifications that prevent all GL 96-06 related waterhammers inside containment. Two modifications were designed and implemented. These modifications were designed to isolate the piping inside containment, the high point in the open loop system, in order to maintain it in a water solid state. This was accomplished by a valve closure scheme that is actuated by low LPSW supply header pressure. Additionally, “controllable vacuum breakers” (pneumatic valves) open on low LPSW supply header pressure to eliminate void formation and collapse while the isolation valves are closing. The pneumatic isolation valve arrangement is single failure proof to open and to close. The Waterhammer Prevention System (WPS) circuitry closes the valves by one of two digital channels consisting of relays, which are triggered by two of four analog channels consisting of a pressure transmitter/current switch. The valves re-open on increasing supply header pressure. A “leakage accumulator” was provided in the supply header to make-up any boundary valve leakage that may occur when the system is isolated. This provides for a larger allowable aggregate boundary valve leakage rate. The system response was predicted by a model using the thermal-hydraulic code GOTHIC. Following installation, an integrated test was successfully conducted by inducing a LOOP into the LPSW system.
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Nelson, Jeremy, Trace Silfies, Brian Crandall, and Jorge Penso. "Review of Life Assessment and Repair Strategies for Hydrogen Reformer Furnace Outlet Header Castings." In ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21555.
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Abstract Steam methane reforming is the most common method of hydrogen production relevant for plants in the petroleum upgrading, downstream refining, methanol, and ammonia industries. Owner-operators of steam methane reformer furnaces continue to make repair and replacement decisions that involve the cast outlet manifold fittings. One key part of these plans is assessment of the weldability and remaining life of the cast components. The 20Cr-32Ni-1Nb alloy casting materials typically used in the outlet manifolds are usually operated in the low end of their creep temperature range but are subject to metallurgical aging mechanisms which reduce their ductility, weldability, homogeneity, and fracture toughness. This paper covers the practices employed by several owner-users to optimize the lifecycle costs of the outlet manifold castings. These practices include but are not limited to controlled materials specifications, in-situ weldability tests, non-destructive testing in-situ and destructive testing post service, and repair practices such as annealing heat treatments. This paper also includes a limited survey of several owner-users and their fleets of reformer heaters. The details in the survey include the population of affected cast manifold components, alloy grades for the castings and welds, operating temperature ranges, number of startup and shutdown cycles, ranges of time in service, generic design details, and repair case studies. Also discussed are recent improvements in the state of the art for high temperature materials property data-gathering, as well as the structural modeling via Finite Element Methods. These new technologies are opportunities for future work to develop better strategies in the areas of condition assessment, repair planning, and remaining life prediction, taking into account the relevant parameters of installed manifold components, including: specific aging behavior of the casting chemistry, component mechanical design details, as well as the welding and heat treatment parameters during initial fabrication and subsequent maintenance activities.
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Chiriac, Victor, and Tien-Yu Tom Lee. "System Level Thermal Optimization of an Automotive Lightning Module Incorporating Several Power Devices." In ASME 2007 InterPACK Conference collocated with the ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ipack2007-33707.
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The conjugate thermal performance of microelectronics module incorporating several power packages and additional passive components in a custom environment is evaluated and further optimized using numerical simulation and experimental validation. The automotive industry deals on a daily basis with multiple packaging and module-level thermal issues when reducing the size of components for a lightning system in a car, while managing the routing of very high current. The study provides a better understanding of the strengths and weaknesses of the IC incorporation into a system module level, for both present and future product development. The reference design is evaluated at a system level, and several improvements are identified to enhance the overall thermal performance of the lightning system. The main concern is related to the possibility of exceeding the thermal budget for a large system incorporating several PQFN (Power Quad Flat No-Lead Package) packages with additional heat dissipation devices in an enclosure, at an external ambient temperature of 85°C. Due to the compactness of the device, there are only limited solutions to extract the heat from the high power dissipation system. The impact on the thermal balance of the trace dissipation, the location and size of the pins connecting the two boards (motherboard and daughter board) forming the system, the header heating and other passive components under various powered conditions are evaluated. A revised model includes additional pins (reduced diameter), modified motherboard and harness structures and their locations; the impact of additional heater traces on both top and bottom surfaces of the motherboard, and a modified daughter board design, is also evaluated. The resulting peak temperatures range from 118.3°C to 137.3°C and the corresponding junction-to-ambient thermal resistances (Rja) vary from 8.4°C/W to 8.8°C/W. Rja is defined as the temperature difference between the peak device and ambient divided by the total power dissipation of the PQFN packages. An optimized design is further evaluated, with lowered thermal resistance from the motherboard, the board-to-board pins, the junction box board, and the wiring harness. The thermal budget is satisfied, as the peak temperatures reached by the two designs are below the 150°C limit. Additional experimental results are used to benchmark the simulation results, within 1–6% accuracy.
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Koripelli, Rama S., and David N. French. "Issues Related to Creep-Strength-Enhanced Ferritic (CSEF) Steels." In ASME 2014 Power Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/power2014-32027.
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T-91 and P-91 are the oldest of a new class of creep-strength-enhanced ferritic steels (CSEF) approved for use in boilers and pressure vessels. These newer alloys develop high strength through heat treatment, a rapid cooling or quenching to form martensite, followed by a temper to improve ductility. As a result, these alloys offer a much higher allowable stress which means thinner sections provide adequate strength for high-temperature service. Most of the applications thus far have been a substitute for P-22/T-22. The primary advantages of T91 materials over conventional low-alloy steels are: higher allowable stresses for a given temperature, improved oxidation, corrosion, creep and fatigue resistance. T23 is also considered as a member of the family of CSEF steels. The alloying elements such as tungsten, vanadium, boron, titanium and niobium and heat treatment separate this alloy from the well defined T22 steel. Although, T23 is designated for tubing application, its piping counterpart P23 has a strong potential in header applications due to superior strength compared to P22 headers. Now that T-91 and P-91 have been in service for nearly 30 years, some shortcomings have become apparent. A perusal of the allowable stress values for T-91 shows a drop off in tensile strength above about 1150°F. Thus, start-up conditions where superheaters, and especially reheaters, may experience metal temperatures above 1200°F, lead to over-tempering and loss of creep strength. During welding, the temperature varies from above the melting point of the steel to room temperature. The heat-affected zone (HAZ) is defined as the zone next to the fusion line at the edge of the weld metal that has been heated high enough to form austenite, i.e., above the lower critical transformation temperature. On cooling, the austenite transforms to martensite. Next to this region of microstructural transformation, there is an area heated to just below the austenite formation temperature, but above the tempering temperature of the tube/pipe when manufactured. This region has been, in effect, over-tempered by the welding and subsequent post-weld heat treatment (PWHT). Over-tempering softens the tempered martensite with the associated loss of both tensile and creep strength. This region of low strength is subject to failure during service. Creep strength of T91 steel is obtained via a quenching process followed by controlled tempering treatment. Elements such as niobium and vanadium in the steel precipitate at defect sites as carbides; this is known as the ‘pinning effect’. Any subsequent welding/cold working requires a precise PWHT. Inappropriate and/or lack of PWHT can destroy the ‘pinning effect’ resulting in loss of creep strength and premature failures. Several case studies will be presented with the problems associated with T91/T23 materials. Case studies will be presented, with the results of optical microscopy, scanning electron microscopy, hardness measurements and energy dispersive spectroscopy analysis. One case study will discuss how the over-tempering caused a reduced creep strength, resulting in premature creep failure in a finishing superheater tube. A second case presents the carburization of a heat recovery steam generator (HRSG) superheater tube, resulting in reduced corrosion/oxidation resistance. A case study demonstrates how a short-term overheating excursion led to reheat cracking in T23 tubing. Another case will present creep degradation in T91 reheater steel tube due to high temperature exposures (over-tempering).