321 research outputs found
Generalized Least Energy of Separation for Desalination and Other Chemical Separation Processes
No full textIncreasing global demand for fresh water is driving the development and implementation of a wide variety of seawater desalination technologies driven by different combinations of heat, work, and chemical energy. This paper develops a consistent basis for comparing the energy consumption of such technologies using Second Law efficiency. The Second Law efficiency for a chemical separation process is defined in terms of the useful exergy output, which is the minimum least work of separation required to extract a unit of product from a feed stream of a given composition. For a desalination process, this is the minimum least work of separation for producing one kilogram of product water from feed of a given salinity. While definitions in terms of work and heat input have been proposed before, this work generalizes the Second Law efficiency to allow for systems that operate on a combination of energy inputs, including fuel. The generalized equation is then evaluated through a parametric study considering work input, heat inputs at various temperatures, and various chemical fuel inputs. Further, since most modern, large-scale desalination plants operate in cogeneration schemes, a methodology for correctly evaluating Second Law efficiency for the desalination plant based on primary energy inputs is demonstrated. It is shown that, from a strictly energetic point of view and based on currently available technology, cogeneration using electricity to power a reverse osmosis system is energetically superior to thermal systems such as multiple effect distillation and multistage flash distillation, despite the very low grade heat input normally applied in those systems.Center for Clean Water and Clean Energy at MIT and KFUPM (Project R13-CW-10
An Economics-Based Second Law Efficiency
No full textSecond Law efficiency is a useful parameter for characterizing the energy requirements of a system in relation to the limits of performance prescribed by the Laws of Thermodynamics. However, since energy costs typically represent less than 50% of the overall cost of product for many large-scale plants (and, in particular, for desalination plants), it is useful to have a parameter that can characterize both energetic and economic effects. In this paper, an economics-based Second Law efficiency is defined by analogy to the exergetic Second Law efficiency and is applied to several desalination systems. It is defined as the ratio of the minimum cost of producing a product divided by the actual cost of production. The minimum cost of producing the product is equal to the cost of the primary source of energy times the minimum amount of energy required, as governed by the Second Law. The analogy is used to show that thermodynamic irreversibilities can be assigned costs and compared directly to non-energetic costs, such as capital expenses, labor and other operating costs. The economics-based Second Law efficiency identifies costly sources of irreversibility and places these irreversibilities in context with the overall system costs. These principles are illustrated through three case studies. First, a simple analysis of multistage flash and multiple effect distillation systems is performed using available data. Second, a complete energetic and economic model of a reverse osmosis plant is developed to show how economic costs are influenced by energetics. Third, a complete energetic and economic model of a solar powered direct contact membrane distillation system is developed to illustrate the true costs associated with so-called free energy sources.Center for Clean Water and Clean Energy at MIT and KFUPM (Project R13-CW-10
ROHINTON MISTRY AS A DIASPORIC AUTHOR
No full textThe writings of the Indian Diaspora have received a great deal of attention and critical acclaim throughout the world. Rohinton Mistry is a well renowned author in the contemporary commonwealth literature and occupies a significant place among the writers of Indian Diaspora. Even though he is settled in Canada; it is his upbringing in Mumbai that reflects in all his writings. The distinct Mumbai culture, particularly the Parsee way of life, the people of the city and even the politics of India are major themes in his novels. Rohinton Mistry as a writer of Diaspora has carved a niche for himself. His works such as: “Tales from Firozsha Baag”, “Such A Long Journey”, “A Fine Balance” and “Family Matters”;mark a new kind of writing, resulting from a fragmented, splintered world. As a Diasporic Parsi writer, very sensitively he has recalled his community’s journey through time and history with a sense of loss and nostalgia. His books portray diverse facets of Indian socioeconomic life; as well as Parsi Zoroastrian life, customs, and religion. Many of his writings are markedly “Indo-nostalgic”. Rohinton Mistry through his Diasporic discourse has well depicted his ancestral background, his community’s engaged situation in a metropolis like Bombay and his deep attachment with and nostalgia for a world gone by. In this paper an attempt has been made to delineate diasporic discourse in the works of Rohinton Mistry. Although he is obsessed with the colonial and postcolonial experiences in India, we can find some traces of Canada in his literature. His characters dream of being integrated into, and accepted by, Canadian society on the one hand and on the other hand, these same characters are torn by an insatiable desire to be true to their native culture; to honor and cherish their own, distinct cultural identity
Rohinton Mistry AS A Diasporic Author
No full textThe writings of the Indian Diaspora have received a great deal of attention and critical acclaim throughout the world. Rohinton Mistry is a well renowned author in the contemporary commonwealth literature and occupies a significant place among the writers of Indian Diaspora. Even though he is settled in Canada; it is his upbringing in Mumbai that reflects in all his writings. The distinct Mumbai culture, particularly the Parsee way of life, the people of the city and even the politics of India are major themes in his novels. Rohinton Mistry as a writer of Diaspora has carved a niche for himself. His works such as: “Tales from Firozsha Baag”, “Such A Long Journey”, “A Fine Balance” and “Family Matters”; mark a new kind of writing, resulting from a fragmented, splintered world. As a Diasporic Parsi writer, very sensitively he has recalled his community's journey through time and history with a sense of loss and nostalgia. His books portray diverse facets of Indian socioeconomic life; as well as Parsi Zoroastrian life, customs, and religion. Many of his writings are markedly “Indo-nostalgic”. Rohinton Mistry through his Diasporic discourse has well depicted his ancestral background, his community's engaged situation in a metropolis like Bombay and his deep attachment with and nostalgia for a world gone by. In this paper an attempt has been made to delineate diasporic discourse in the works of Rohinton Mistry. Although he is obsessed with the colonial and postcolonial experiences in India, we can find some traces of Canada in his literature. His characters dream of being integrated into, and accepted by, Canadian society on the one hand and on the other hand, these same characters are torn by an insatiable desire to be true to their native culture; to honor and cherish their own, distinct cultural identity
Effect of nonideal solution behavior on desalination of a sodium chloride (NaCl) solution and comparison to seawater
No full textProper evaluation of the Gibbs free energy and other properties
of seawater and other aqueous solutions is essential in
the analysis of desalination systems. Standard seawater has
been studied extensively and property data are readily accessible.
However, many aqueous solutions requiring desalination have
significantly different composition from seawater and seawater
data is generally not accurate for these solutions. Experimental
data for a given aqueous solution may be unavailable under the
conditions of interest. Therefore, there is a need to model relevant
physical properties from chemical thermodynamic principles. In
particular, for solutions that are not ideal, the activity and fugacity
coefficients must be considered. In this paper, the effect of
nonidealities in sodium chloride (NaCl) solutions is considered
through a parametric study of the least work of separation for a
desalination system. This study is used to determine the conditions
under which the ideal solution approximation is valid and
also to determine when an NaCl solution is a good approximation
to standard seawater. It is found that the ideal solution approximation
is reasonable within ranges of salinities and recovery
ratios typical of those found in the seawater desalination industry
because many of the nonidealities cancel out, but not because
the solution behaves ideally. Additionally, it is found that NaCl
solutions closely approximate natural seawater only at salinities
typically found in seawater and not for salinities found in typical
brackish waters.Massachusetts Institute of Technology. Center for Clean Water and Clean EnergyKing Fahd University of Petroleum and Minerals (project number R13-CW-10
An improved model for multiple effect distillation
No full textIncreasing global demand for fresh water is driving research and development of advanced desalination technologies. As a result, a detailed model of multiple effect distillation (MED) is developed that is flexible, simple to implement, and suitable for use in optimization of water and power cogeneration systems. The MED system is modeled in a modular method in which each of the subcomponents is modeled individually and then instantiated as necessary in order to piece together the complete plant model. Modular development allows for studying various MED configurations (such as forward feed, parallel feed, etc.) with minimal code duplication. Use of equation-oriented solvers, such as Engineering Equation Solver and JACOBIAN, rather than sequential solvers, simplifies the coding complexity dramatically and also reduces the number of required approximations and assumptions. The developed model is compared with four prominent forward feed MED models from literature. Through parametric analysis, it is found that the present model compares very well with the simple model provided by El-Sayed and Silver while providing substantially more detail in regard to the various temperature profiles within the MED system. Further, the model is easier to implement than the detailed El-Dessouky model while relying on fewer assumptions. The increased detail of the model allows for proper sensitivities to key variables related to input, operating, and design conditions necessary for use in a cogeneration or hybrid system optimization process.Center for Clean Water and Clean Energy at MIT and KFUPM (Project R13-CW-10
Optimal operating conditions and configurations for humidification–dehumidification desalination cycles
No full textThis article applies nonlinear programming techniques to optimize humidification–dehumidification (HD) desalination cycles for operating conditions that result in maximum gained output ratio (GOR). Closed air open water as well as open air open water cycles, each with either an air or a water heater, were considered in this analysis. Numerical optimization resulted in a substantial increase in GOR for all four cycle types compared to previous best-case conditions found using heuristic studies. The GOR of the cycles was found to decrease with increasing component terminal temperature difference (TTD). In addition, different cycles perform best at different temperature differences. Optimization also revealed that some counterintuitive design configurations can result in superior performance under the appropriate operating conditions.Center for Clean Water and Clean Energy at MIT and KFUP
Internal Analysis of factors affecting Aster Pharmacy in India.docx
No full textInternal Analysis of Factors Affecting Aster Pharmacy In India(This is an academic research paper, subjected to copyright)Owner/Author and Creator: Nidhi Mistry</div
Experimentation of the Language in the Novels of Rohinton Mistry
No full textIndia is a multi-lingual, multi-cultural and multi-ethnic country, and it is one of the major demands of post-coloniality that Transcreation work should be carried on for the sake of literary expansion, national integration and international co-operation. The purpose of this Research Paper is to dwell on the relevance and usefulness of Transcreation as well as creative use of English in the fiction of Rohinton Mistry with reference to his novels Such a Long Journey (1991), A Fine Balance (1996) and Family Matters (2002). Rohinton Mistry mixes Hindi words along with Urdu, Gujarati and Parsi words in his narration to reinforce the impact of his narrative. Mistry being a Diasporic author experimented with the bilingual –and the bicultural competence of the reader in creating a hybrid identity that is typically and multiculturally Indian. Key words- Transcreation, Multi-lingual, Multicultural, Parsi
External Analysis of factors affecting Aster Pharmacy in India.docx
No full textExternal Analysis Affecting Aster Pharmacy In India(This is an academic research paper, subjected to copyright)Owner/Author and Creator: Nidhi Mistry</div
- …
