RefrigerationRefrigeration involves the cooling of bodies an.docx
- 1. Refrigeration Refrigeration involves the cooling of bodies and fluids to levels that are below those of the surroundings. Refrigeration involves two processes, one is the absorption of heat at lower temperature, and the other is the rejection of heat to higher temperatures. When the refrigeration was invented, the sole purpose of this phenomenon then was to produce ice, which would then be used for mainly preserving food, cooling beverages, and refrigerated transport. Today, refrigeration has found many other uses that it is now an essential feature of life. Without refrigeration, the basic fabric of life would be significantly affected. Indeed, in the modern life refrigeration plays an indispensible role. Because of the refrigerator’s contribution, the expiration time of foods can be carried forward; it is now possible to keep fresh foods beyond their typical expiration dates (Hundy, et al 16). Suffice it to say that the refrigeration is one of the most valuable processes in homes today. These magical equipments are craftily made to turn on after every five minutes to keep everything therein cold. Without refrigeration, there would be huge chunks of food that would be going to waste every day. There are four major application of refrigeration. The four areas are equally important. These are: food processing and preservation; chemical and process industries and special applications. Food processing and preservation feature of refrigeration also involves distribution. This application integrates the storage of vegetables and raw fruits. Some bacteria cause degradation of food, while enzymatic processing effect on vegetables and fruits case them to ripen more. The refrigerators’
- 2. create a law temperature that reduces the growth of these bacteria and enzymatic processes reducing spoilage while improving the food’s shelf life. The other application of refrigeration involves chemical and process industries. Industries such as petrochemical plants, petroleum refineries and paper pulp industries require extremely large cooling capacities (Chhandra 365). The main application of refrigeration in these key industries involves several fundamental categories. These are separation of gases, condensation of gases, and solidification of solute and dehumidification of air. The other application of refrigeration involves special application. Apart from the chemical uses, this category looks at other broader applications such as construction units, manufacturing processes and applications in medicine among others. Others in this special category of refrigeration uses include cold treatment of metals, ice skating links, ice manufacture and desolation of water. The ideal Carnot cycle is a refrigeration cycle that frequently employs constant temperatures external heat source as well as heat sinks. The Carnot cycle is a process where a substance, which in this case is the refrigerant, circulates through four devices. The objective here is to transport heat out of the refrigerator and dumping it into the kitchen. A schematic of the ideal Carnot cycle is illustrated below. In this process, the refrigerant can be an ideal gas which has a constant specific heat; this could for instance be helium (“The Reversal Ideal.”). Figure 1: Schematic of the Carnot refrigeration cycle Source: “The Reversal Ideal.” N.d. 2 March, 2014. http://www.eng.fsu.edu/~dommelen/quantum/style_a/qsrev.html
- 3. Stability of the refrigerant is very critical because of a number of reasons. The use of an impure refrigerant causes some interrelated changes that collectively compromise the operation, performance, longevity as well as the safety of the system. As such, chemical and thermal stability of the refrigerant is an important consideration in selecting the refrigerant in the refrigeration system. The trend of using flammable refrigerants seems to be on the rise. There is need to follow for strict procedures and standards when using flammable refrigerants. These refrigerants include hydrocarbons that are being used in both small integrated systems and larger ones as well. Refrigerant used in food preservation and air conditioning must be non-toxic and non-corrosive in nature. This factor should be considered because these will come into contact with the lives dependent on the system. Refrigerants would negatively affect human health is they were corrosive and toxic in nature. These two characteristics introduce the issue of environmental considerations of choosing a refrigerant. The two deal with the effect that the refrigerant on the ozone layer and the contribution it has on global warming. Ammonia remains the most commonly used refrigerant. It is also the most trusted. Ammonia offers some key advantages when used as refrigerant. It is environmentally compatible, has better thermodynamic qualities and has a recognizable odor which makes it its most critical asset. Other industrial refrigerants do not have an odor meaning that if there was a leak it would go undetected. These refrigerants have proved to be safe and effective becoming the most used refrigerants today. The completely halogenated hydrocarbons are referred to as chlorofluorocarbons
- 4. (CFCs). In CFC, all hydrogen atoms are substituted with chlorine and fluorine atoms(Chhandra 366).Halogenated hydrocarbons have no negative effect on the atmosphere. Cost Availability Environmental impact Performance Safety Stability Toxicity and corrosiveness Flammability Ammonia Low Highly available Environmentally compatible High performance Safe to use but toxic Offers stability Toxic Not flammable hydrocarbons Low Harmless to ozone layer Offers great performance Not harmful Non corrosive Highly flammable CO2 Low Readily available
- 5. Harmless to ozone Low efficiency Very safe excellent stability Non toxic and non corrosive Non flammable The refrigerant that would be best for automobile must combine a number of factors. It must be non flammable, non toxic and have limited impact on the ozone layer and environment in general. The possibility that bets guaranteed this is carbon dioxide. Carbon dioxide is a safe, non-flammable and non-toxic alternative to ammonia and Halogenated hydrocarbons. The reason why CFC would not be appropriate is its serious threat to the environment. When studies on the substance found out that CFC released into the atmosphere tends to accumulate in the stratosphere. This had a depleting effect on the ozone layer. However, CFC is both non corrosive and non toxic. Ammonia is environmentally compatible but it is a toxic gas. As such, the most appropriate refrigeration for an automotive air- conditioning system would be carbon dioxide. Carbon dioxide provided a sustainable solution to automotive air-conditioning system. Indeed, many next generation advances in this area are increasingly experimenting with CO2 in the automotive air conditioning. Sustainability comes with the consideration that this process will involve recycling waste CO2 and using it as a natural refrigerant, therefore turning the problem of CO2 into a workable solution. Works Cited Hundy, G.H, Trott, A.R., and Welch, T.C. Refrigeration and Air Conditioning. 4th Edition. Oxford, UK: Elsevier Chhabra, Raj P. CRC Handbook of Thermal Engineers. New York, CRC Press. “The Reversal Ideal.” N.d. 2 March, 2014. http://www.eng.fsu.edu/~dommelen/quantum/style_a/qsrev.html
- 6. 4 Alotair 3 Did Gandhi Influence on Martin Luther King, Jr. principles of non violent agitation for basic human rights? Liqaa Alotair Facilitator 26th March 2015 Michale J. Nojeim Gandhi and King: "The Power of Nonviolent Resistance." Greenwood Publishing Group 331 pages Jan 1 2004. Michale J. Nojeim in this book looks at the various similarities shared by both Mohandas Koromchand Gandhi and Martin Luther King Junior as regards their stand on use of non violent means in seeking equality for their various communities. He presents the individual lives of both men starting with Gandhi’s and then Kings Life, and compares how both men used nonviolence as a strategy for communicating the various grievances of their people
- 7. .Michael J, Nojeim is a distinguished authority in political science and teaches Gandhi and King he also specialises in non violence making his book a good addition to this research. Burrow Rufus. “Martin Luther King, Jr. for Armchair Theologians”. Westminster John Knox Press, 2009 - Religion - 194 pages. Burrows in this text looks at the life of Martin Luther King Junior. He investigates the way King thought as well as his life. The book looks at how King adopted various Gandhian principles into the struggle of the South and how he modeled them to the troubles in the South. It chronologies the conversion into using nonviolence strategies. Over the last two decades Rufus Burrow has authored many texts on Martin Luther King; this therefore makes his voice a good Addition to this research process as it helps to see what doctrines of Gandhi that King used in his campaigns and the journey to his conversion into Gandhism. Pandiri Ananda M. “A. Comprehensive, Annotated Bibliography on Mahatma Gandhi: Books and pamphlets about Mahatma Gandhi”. Volume 2 of A Comprehensive, Annotated Bibliography on Mahatma Gandhi, Ananda M. Pandiri Greenwood Publishing Group, 1995. Ananda M. Pandiris in this book looks at the life and times of Mohandas Gandhi. He chronologies in a very comprehensive manner a bibliographical account of Gandhi gotten from publishers, libraries, from India to Britain the US and South Africa where Gandhi stated for 21 years. The author of this book has extensive knowledge of Gandhi and travels the world teaching and researching on Gandhi. Compared to the book by Rufus Burrow this book looks at Gandhi while Burrows looks at Kings Life and legacy and together this books tell the stories of
- 8. this different men and will help in making comparison more easily. This text will help in bringing out the details of the maikingof a civil activist and what made Gandhi the man he became4 Lakshmi Rama. “Son Marks Martin Luther King's 1959 Visit to India”. Washington post. Wednesday, February 18, 2009.Web. 15th Feb. 2015. This news paper article looks at the pilgrimage of Martin Luther King the third to India where he went to retrace his father’s footsteps from when he had visited in February of 1959. Martin Luther King III while in India learnt of the special honor his father bestowed upon Gandhi during his visit fifty years back when he and his mother Coretta Scott King had visited, and learnt of the nonviolent ways used by Gandhi . Gandhi it is said in the article had immense influence on how Dr. King chose to run the Civil rights movement in America, and while in India, King visited many places where Gandhi had lived even sleeping in a room he had slept in. This resource is going to be a good contribution to the argument on how Gandhi influenced Dr King’s philosophy on non violence as it speaks of his pilgrimage and of his son after that and of how people from both America and India saw and still see this connections. This article complements the works of Michale J. Nojeim which compared the lives of the true great civil rights activists now this shows as one of the leaders experiences first-hand the experiences of the other and his son carrying on the torch of exploration of the values both men held so dearly.5 5 Gandhi in his various interactions with then British colonialists of India eventually led to the freeing of India after 200 years of British rule. “Martin Luther King, JR. AND THE GLOBAL FREEDOM STRUGGLE.(n.d.).Web. Feb 15th 2015.
- 9. This article looks at the life of Gandhi and how he influenced the political reforms of both India and America through his standing up against the British and in his influence of Martin Luther King. According to this page King's first interaction with Gandhi’s principles was at the Crozer Theological Seminary. In one of his classes he is said to have singled out Gandhi as "Individuals who greatly reveal the working of the spirit of God" .It adds that King placed Gandhi’s philosophy at the same level as Christianity and he says that “Christ showed us the way and Gandhi in India showed it could work. This article is a good addition to the other mentioned sources in this text as it shows the beginning of Dr King’s relationship with the ways of Gandhi thus further strengthening the fact that he was heavily influenced by Gandhi’s ways6 6 The first time Martin Luther King used strategies of non violent direct action was during the 1955 to 1956 Montgomery bus boycotts � A look into how Martin Luther King Junior was influenced by the nonviolence doctrines as practiced by Mahatma Gandhi. � A Child Shall Lead Them: Martin Luther King Jr., Young People, and the Movement Extremist for Love: Martin Luther King Jr., Man of Ideas and Nonviolent Social Action Their life’s work and their ultimate sacrifice-by an assassin’s bullet as each tirelessly and steadfastly preached nonviolent reconciliation-point us in the direction that will leave all people with more hope for the new millennium.
- 10. � Some of the books that Rufus Burrows has authored on Dr. King include “ A Child Shall Lead Them: Martin Luther King Jr., Young People, and the Movement Also Extremist for Love: Martin Luther King Jr., Man of Ideas and Nonviolent Social Action use it: it is economical and flexible. 4 The author of this book has extensive knowledge of Gandhi and travels the world teaching and researching on Gandhi. Page 1 of 3 ES 3053 Design Project Spring 2015 Part 1 Due March 2, 2015 Part 2 Due April 6, 2015 Part 1: Write a 2-3 page essay broadly discussing the choice of refrigerants for refrigeration systems. What are important considerations when deciding on a refrigerant for any type of refrigeration system (not just automotive applications)? Topics which may be discussed include desirable physical and thermodynamic properties, toxicity, cost, corrosion properties, etc. Use at least three references (none of these can be from the internet – they should be books, journal papers, magazine articles, patents, or other
- 11. similar references) for your essay and be sure to properly cite all the works you refer to. You can use any standard reference format you like (e.g., APA, MLA, Turabian, etc.). Be consistent and use the same format style for all references. Compare at least 3 different potential refrigerants on at least 8 different criteria. You should weight the relative importance of each characteristic and quantify each as best as you can. For example, cost may not be as important since relatively little refrigerant would be needed in a car A/C system. In some cases you may use qualitative comparisons such as poor, good, better, best, etc. The best way to make the comparison of 3 refrigerants on at least 8 criteria is with a table, so they can be compared side-by-side. Finally, make a recommendation on what refrigerant you would chose for an automobile if you were going to manufacture an air- conditioning system for automotive use. Example Outline: 1. Introduction 1.1. Purpose of refrigeration 1.2. Sample applications 1.3. Briefly discuss ideal Carnot refrigeration cycle 2. General Refrigerant Characteristics 2.1. Stability, flammability, toxicity, corrosivity, cost, ozone depletion potential, global warming potential, COP, etc. 3. Refrigerant Possibilities 3.1. Ammonia, CFCs, halogenated hydrocarbons, hydrofluorocarbons, etc.
- 12. 3.2 Comparison of at least 3 possibilities 4. Conclusions/Selection 5. References Appendix (include a schematic of a Carnot refrigeration cycle) Part 2: Perform the thermodynamic design calculations for an air- conditioning system for a specific automobile of your choosing (give the make, model, and year of the vehicle). DO NOT use a generic automobile. Your design should include only the thermodynamic aspects with a flow schematic showing anticipated temperatures, pressures, entropies, enthalpies, flow rates, heat loads, and work requirements, but the mechanical design (piping sizes, compressor parts, mounting mechanics, etc.) need not be Page 2 of 3 evaluated. Be sure to use the refrigerant you selected in Part 1 of this project. Include a copy of the graded Part 1 as an attachment to the final report. Discuss assumptions that you make, and give reasons that you made the assumptions. Determine how much cooling capacity is required to cool a specific car interior with full occupancy. Assume the highest temperature location in the U.S. and add another 5°C for the greenhouse effect when sunlight comes into a closed car on a hot summer day. Assume the metal, plastic, fabric, etc. in the car is heated to that temperature.
- 13. Specify the weight of each component that will be cooled, how fast the interior should be cooled down and to what temperature everything should be cooled down to (except the people who will not be cooled down much below 98.6°F). Assume the refrigeration system is an ideal Carnot refrigerator. You should calculate the following: Assume simple micp i (T2-T1) calculations for each material i to be cooled down. Assume no additional heat is added to those materials during the cooldown. period If you choose a refrigerant that is in CATT, you may use it to calculate the refrigerant properties. Put a table in the Appendix of your report that includes: at each point in the cycle. This project will be a technical report for an engineering
- 14. project. Part 2 should also include Part 1 with any recommended changes by the instructor. The final report should be completely integrated with both parts and should not have 2 separate parts, nor 2 sections labeled Part 1 and Part 2. The total maximum length is 7 pages including all figures and tables, but not including the cover page, the Table of Contents, the list of references, or Appendix. Example Outline: 1. Introduction Include a statement of the project and the scope of your work. 2. Discussion Include discussion regarding choice of refrigerant and other assumptions that you made to solve the problem. 3. Calculations Give a synopsis of the important aspects of the calculations. Don’t include too many details such as intermediate iterative calculations, but provide enough details so that your calculations could be checked for accuracy. 4. Schematic Page 3 of 3 General Specifications list them in the References)
- 15. margins all around Table 1. Comparison of refrigerants.) (e.g., Figure 1. Refrigeration schematic.) report (i.e., you can’t have any figures, tables or equations that appear in the report but are not mentioned in the report) unnumbered; the Table of Contents is numbered as i not create use person pronouns (e.g., I, we) – technical writing should be in the third person Appendix many you will lose points)
- 16. is too long to fit on 1 page, then the table headings must be repeated again on every page where the table appears