Heat Exchange In Refrigerator System

Heat Exchange In Refrigerator System INTRODUCTION The intend heat exchangers, such as condensers and evaporators, very much influences energy effectiveness of the refrigeration system. A properly designed heat exchanger will not simply helps decrease energy consumption but in addition reduce cost and increase storage volume. Recovering energy efficiency and reducing cost essentially poses a multi objective optimization problem. As these objectives are differing, no single design will satisfy both at the same time. Generally, heat exchanger optimization can be classified into system-level optimization and component-level optimization as in system-level optimization. a complete system is analyzed while component level analysis is performed by separating the heat exchanger from the system by providing proper junction boundary conditions. Previously it has been used design optimization methods, which are merely thermodynamic in nature, for example entropy generation minimization (EGM) The main concept of EGM is that if entropy, which measures the irreversibility of the system and minimized followed by systems performance improvement the technique is used to optimize heat-exchanger list between the condenser and evaporator. The resultant system from the analysis is the good   energy efficient, but   may not be good for an economic point of view a new approach was projected which integrates economics with thermodynamic optimization, which means   the ‘‘thermo-economics approach. Th ermo-economics blends two very dissimilar fields thermodynamics and economics, making it predominantly suitable to design thermal systems with efficiency and capital cost. (Gholap et.,2007 ) . Condensation heat transfer, equally inside and outside horizontal tubes, plays a main role in refrigeration the science of condensation heat transfer has been adopted a substitute working fluids and new improved surfaces for heat exchangers. (Cavallini, A etal.,2003) Literature review Literature review and discussion for heat exchange in refrigerator system There are many   publications focus on heat exchangers in an refrigerator system   has have quite a lot of design variables such as geometry, surface finish, Material In this work. These variables are inhibited by various reasons such as manufacturing capability and space limitation. Heat exchanger has many variables, e.g. number of rows, width, fin density, tube diameter, tube spacing, fin spacing, etc. Dependent variables are the characteristics of the design household refrigerators, energy consumption, cost, and internal volume can serve as independent variables. (Gholap,,2007 ) describe heat optimizing system in an refrigerator system the study was proposed considering overall energy-consumption and heat-exchanger with low cost material which was multi-objective optimization problem. Thus he tried to calculated over all energy-consumption   by adding the energies consumed by the compressor, fan motors, and defrost heater for a 24 hours period and heat-exchanger   costs of material were calculated by means of   individual weight of the coil multiplied through the rate per unit and weight of the correspond metal in the market. His researched   was focus on various kinds of design of the condenser for heat optimizing, most household refrigerators has   wire-on-tube design for the condenser and finned tube Design for the evaporator which is used extensively according to research heat exchanger is divided into along length, height and depth each of element has refrigerant and air steam. However, heat optimizing system does not show much development Thus, The designer can prefer a resolution based on the manufacturers strategic direction regarding cost and the Energy-consumption requirement. A research on wire on tube condenser by (Lee, TH.,2001) observes the correlation on the airside heat transfer coefficient of wire-on-tube type heat exchangers by   using single layer tube   rather than using bundles of tubes. The improved correlations were based on Zhukauskas correlation which discussed via the numerical analysis. Thus Concluding the ratio of Zhukauskas correlation for a single cylinder to the heat transfer coefficient across to the air flow in the wire-on-tube type heat exchanger is constant and the heat transfer parallel to the air flow in the wire-on-tube type heat exchanger. Hence, Zhukauskas correlation has a more accurate prediction result compared to the existing cases. Another research was proposed by (Yang, C, 2005) presenting the numerical results of the consequence of dissimilar parameters on the performance of capillary tube-suction line heat exchangers (CT-SLHX), together with condensing and evaporating temperatures, degrees of sub cooling and superheat, tube diameter, tube length, and refrigerant flow inlet quality. The effects of different geometric and operation circumstances on the capillary tube performance and investigated that the best design present capillary tube-suction line heat exchanger exists about 3 K of sub cooling and 1.4-1.6 m of the heat exchanger length. Further found that R-134a performs better in terms of heat transfer rate and evaporator capacity than R-600a and heat transfer rate from the capillary tube to the suction line decreases by about 8-10% when non-adiabatic inlet arrangement is used compared with adiabatic Wire-on-tube Design The most extensively used condenser in refrigerant system since many years is wire-on-tube design used for the condenser and finned tube design intended for the evaporator. Wire-on-tube type heat exchanges consists of tube bundles within which a heat transfer medium such as refrigerant is strained to flow, whereas a second heat transfer fluid like air is concentrating transversely through tubes. As the airside thermal resistance of this heat exchanger is much advanced than that of refrigerant side, improved surfaces such as wires straight welded on the sequence of tubes are engaged to successfully reduce the resistance as in the other finned tube heat exchangers. Even though these are widely used in home refrigerator for low cost and simple making, the general design data and correlation for the airside heat transfer be not easily obtainable. This makes additional studies have been focused on the research area for cycle matching and frosting. The airside heat transfer coefficient of heat exchanger will be able to calculated using the following two methods: The heat transfer coefficient of tubes and wires can be obtained, respectively, by multiplying Zhukauskas correlation by correction factor Results is formulated directly by performing the heat transfer experiment on wire-on-tube heat exchanger. (Lee,TH.,2001) Capillary Tube-suction Line Heat Exchange Optimizing a capillary tube-suction line heat exchanger is beneficial designers for vapour compression refrigeration systems and better enhancement of the system performance. A capillary tube is extensively used in household refrigerators owing to its low cost and effortlessness. It improves the system capability by minimizing the evaporators inlet-enthalpy. In addition it act as a shield for the compressor and increases the inlet temperature. (Gholap 2007) .The capillary tube and the suction line figure a counter-flow heat exchanger. Refrigerant vapour is condensed as of the evaporator to the condenser in process and is packed together in the condenser throughout the process. A non-adiabatic throttling procedure is implicated throughout process where heat is transferred from the capillary tube to the suction line throughout process, while at the same time heat is separate from the evaporator for the duration of process The heat transfer from the capillary tube to the suction line over and over again leads to the upgrading in the thermodynamic efficiency of the system owing to the condensed refrigerant quality and towards the inside of the evaporator. Moreover, the transfer of heat to the suction line ensures the refrigerant vapour enters the compressor by this means of eliminating suction line sweating and preventing slugging of the compressor. The capillary tube has been extensively investigated even though a few numerical models of t he non-adiabatic capillary tubes are existing but there require understanding on some flow phenomena within a tube, such as the reverse heat transfer, the re-condensation, and the chocked flow of the condenser in a refrigeration system. Some phenomena possibly will cause unstable flow in the capillaries the two-phase flow heat transfer coefficient has commonly been believed to be infinite. This hypothesis may be unsuitable in situations, where re-condensation or overturn heat transfer possibly will occur from the suction line to the capillary tube under distant operating conditions. This precise hypothesis of infinite heat transfer has been undisturbed in the present model by using suitable two-phase heat transfer correlations to reproduce the actual flow performance inside the capillary tubes. As a result a numerical investigation of refrigerant flow due to non-adiabatic capillary tubes through modifying the computer model developed. (Gholap 2007) Numerical Model Restricted element approach and suitable heat transfer correlations are integrated into the model to calculate the performance of the capillary tube-suction line heat exchanger. This model is of two modes: Design mode: to calculate the capillary tube length for the specified refrigerant flow rate, Simulate mode: to estimate the refrigerant flow rate for the particular tube length. . The finite-element The model comprises the operating surroundings of the refrigeration system, geometrical Parameters of the capillary tube-suction line heat exchanger and refrigerant properties. This capillary tube separated into three sections. Adiabatic inlet region (connecting the condenser), the heat exchange region and the adiabatic Outlet region (connecting the evaporator).refrigerant flow inside the capillary tube comprises of two regions: the single-phase region and the two-phase region. Numerical solution is conceded out and separating the flow domain into small essentials by the side of the capillary tube and the suction line. The length of each control volume model is 1 mm. Homogeneous flow theory analyzes the two-phase flow inside the capillary tube. The model is based on the conservation of mass, momentum and energy; these equations are solved at the same time all through an iterative process. Within the design, the mass flow rate is an input and the sum of total length of the capillary tube is an output, whilst in the replicate case, the capillary tube length is an input and the mass flow rate is an output, which is evaluated iterative process, The calculated length is compared among the given capillary tube total length, thus the supposed mass flow rate can be adjusted. (Yang, 2005) Enhanced tubes of condensers Air-cooled in addition to water-cooled condensers with in-tube condensation of refrigerants are extensively used in water chillers, air-conditioners .Trying to replicate the physics of the condensation procedure analysis on condensation of refrigerants believe to be the transition faced next to the air-conditioning and refrigeration industry in recent years, An introduction of latest ozone friendly refrigerants as substitute for CFCs and HCFCs. Condensation with horizontal tubes, the two point flow is conquered by vapour shear or gravity forces. At the same time annular flow pattern has high vapour shear, wavy and slug flows become visible when gravity is the controlling force. In refrigeration applications with halogenated working fluids, better tubes are frequently used in bundle condensation. Tubes with two-dimensional or three-dimensional external fins are used in few cases they can also be internally amplified to increase the water-side heat transfer coefficients, when fouling is not a problem Bundle condensation has investigated, for reliability in heat transfer. The use of geotropic mixtures combination with bundle condensation should be dejected as it can give rise to relevant refrigerant composition shift. (Cavallini A et al., 2003) Research question HOW TO HEAT OPTIMIZING TECHNIQUE AND EFFICIENCY IN HOUSEHOLD REFRIGERATOR SYSTEM? AIMS The study of the project proposal is based on optimizing heat exchangers in the house hold refrigerator systems. A multi-objective optimization procedure is implements and finding out optimal design which minimise energy consumption and material cost for the household refrigerator systems. The study considers various design of optimization of heat exchangers. Objective To research on properly designed heat exchanger that will help to decrease energy consumption. To carried out a literature review on reducing the energy consumption   refrigerator systems and also in low cost and increase the volume storage Research method Research method is a process of getting better knowledge and understanding of work from peoples those who previously experienced and in some of the research is to take action on previous peoples understanding (Marshall and Rossman, 1999). In a research data can be collected from two sources primary research and secondary research. The primary research is to conducting interviews. These interviews help get knowledge and data for the key research issues and also to get different views of peoples .according to (silverman, 2004) interviewing play a key role in getting an large amount data in quick time .lot of researches make use of interviews to get a clear structure .and in secondary research that data is collection by means of document, previous research, articles, publication and text book. For this research the secondary source has been used. Research design   Research design play a very important role in research to know the topic is researchable or not. The research design has to consider the three elements philosophical assumptions, specific research method and strategies of inquiry and also research question (John, 2009) .For this research. The first task is to find out the research topic which is related to the field and researchable. The choose topic was heat optimizing technique and efficiency in household refrigerator system. Because this topic related to the field and find interesting.After finding the topic the next task was to find literature reviews. After finding all the resource for the topic outline all the important points and start writing. Data collection Data collection involved collecting data by the source of primary and secondary. Collecting data involved in selecting data from different source and the techniques of data, that will collected for the purpose of final research (Silverman, 2004) according to (Sapsford, Roger and   Jupp, Victor;2006) Research doesnt involves in first hand data collection, but it can   also based on the made material available made by other peoples. In this assignment the secondary source has been used to collect data for the research and all the material in the net treated with caution because it can be false. Therefore the data has been collected from the source NORA which is available in Northumbria University and the other source is Northumbria library for referencing text book for this research. Data analysis Data analysis is a process of brining all the collected data and structure for the research. Overview of research Heat exchangers can have several design variables which are controlled by various reasons such as width, fin density, tube diameter, tube spacing, fin spacing, and so on. Energy-consumption and heat-exchanger which form a multi-objective optimization difficulty, Optimization was stopped after 50th generation ever since no additional development was observed. The explanation is divided into two regions.   Region one represent energy efficient and cost-efficient compared with the baseline design. Region two represents both energy and cost is better than for the baseline design. In the case of cost efficient solutions, condenser conductance stays close to its minimum value. For energy-efficient solutions, it stays close to its maximum value with an enhancement in the evaporator conductance thus; region two is most desired optimization. RESOURCES/CONSTRAINTS The mainly used resources need for a research is websites, journals and text books for getting the information and previous research papers and the constraints are Time management for the research Find the research work for writing a literature review. Access to the websites which is held by an engineering organisation. Finding books related to the research topic. Collecting data from different resources. For designing the software used is solid works 2010.

Harley Davidson Essay

What are the key elements of Harley Davidson’s efforts to build relationships with its customers? The main element of Harley Davidson’s success with its customers is idea that owning one of their bikes gives you an elite status and let’s you join an exclusive community. Some of the ways they have built this image is by offering events where the owners can meet each other and form friendships. They also offer services directly through the Harley Davidson Company such as insurance, theft rewards and shipping, and even an exclusive apparel line. Harley Davidson has also continued to produce its bikes in the United States and portrays itself – and in turn, its buyers- as patriotic. It has become an icon of American freedom and consumers want to be a part of it. Can you think of other companies that create such strong relationships with their customers? How do they do that? Rolex is another company that offers its customers an elite product. Like Harley Davidson they have built an elite community and offer special services to owners of Rolex watches. One of their famous services is the registration of the serial number, which not only helps trace stolen watches, but once helped identify a body in a murder case. In 1996 a murder victim was found in the English Channel- it was so decomposed that it could not be identified. Then a Rolex was found on the victims arm and the serial number was used to indentify the victim. In a twist, thanks to the precision works of the watch and its waterproof feature, the time of death was also determined within a few hours. Rolex has always been a company that provides customer service above and beyond any regular level. To own a Rolex means that you have reached a certain level of success. How else can Harley Davidson build or deepen its relationships with its customers? For a long time, Harley has been a man’s world with women being little more than the icing on the back of the bike. Today more and more women are being attracted to the riding experience. Many of them come because they have husbands or boyfriends who ride and they have found they enjoy the experience. Harley Davidson needs to expand on this interest and start offering incentives for female riders, such as bike fests targeting females and female biking apparel similar to the men’s lines. Perhaps a campaign showing real female riders in their day jobs or with their families, and then with their bikes would bring the appeal to the attention of other women that may be interested and would play on the duel role most women have.

Traditionl Healers in Latin America

Introduction Traditional healers also known as curanderismo are important part of Latin American culture, society and a way of life. Traditional healers have been a part of Latin American culture for thousands of years and even today are considered as important as the traditional health care professionals (Avila, 1999). The services of these healers are used extensively and they are well respected and admired members of the community. Not anyone can be a healer and in order to become one a special talent and extensive training is needed (Avila, 1999).The purpose of this paper is to discuss the role of traditional healers in Latin American culture and to discuss what economic, social and religious reasons traditional healers are still so popular in this day and age in Latin America. Who Can Be a Traditional Healer? One of the most interesting aspects of the traditional healers in Latin America is that no everyone can be one. This is a striking contrast with traditional medical profess ionals where calling has become something secondary and where more people than not go into the medical field not because of genuine desire to help but because it pays well.The story is completely different for the traditional healers as the next generation is carefully hand-picked based on what is called â€Å"el don† or a gift (Avila, 1999). This gift cannot be acquired or trained, a person either has it or not. Having gift is not enough though as a new apprentice has to train for a very long time under the practicing traditional healer in order to learn the mastery and the craft of healing (Trotter & Chavira, 1997). Another interesting distinction between what Latin American traditional healers and regular health care professionals is the core philosophy that underlines their work.Traditional medicine focuses on symptoms and causes, while for the traditional healer the most important core of any problem is spiritual one, as the illness is the essentially an imbalance that h as to be corrected (Trotter & Chavira, 1997). Healers are also very in tune with nature and as it will be discussed below they rely a lot of natural remedies and so on (Avila, 1999). Spirituality and religion go hand in hand because as it was mentioned above healing powers are considered the unique gift one has received from some higher entity and thus religion plays very important role in the work of traditional healers.What Exactly Do Traditional Healers Do? Remarkably just like any health care professionals, traditional healers in Latin America also have their own specializations and areas of practice. While some have very narrow and specific areas, such are herbalists or midwives for example; others often have been trained in various specialties and can provide the â€Å"full package care† (Trotter & Chavira, 1997). Regardless of the specialty every traditional healer always considers the illness as a complex manifestation of problems in physical, emotional and spiritual planes.Traditional healers use variety of means in their practices. They prepare various mixtures, lotions, potions, oils and other substances for consumptions or for external use. But the substances are only the part of the practice. There are many rituals, offerings and prayers that constitute healing practices. The rituals could be very elaborate and include other objects and things such as for example birds’ eggs, or water or fire. All these things are believed to be important components in the healing process and are more often than not part of the ritual.Healers often give their clients various amulets to protect or to heal them including bracelets, necklaces and other objects. Many herbal and plant matters are used including very common veggies, spices and fruits like papaya, potatoes, garlic, cumin, mint and others (Davidow, 1999). Finally traditional healers employ many psychological means as they are often keen observers and student of human nature (Trotter & Chavir a, 1997). Many healers admit that the use of rituals is done for the patients’ sake as it aids in healing process.Remarkably there is a scientific support to this notion as the â€Å"placebo effect† indicates that something with strong suggestive power can deliver desired results. Economic, Religious, and Social Explanation For the Use of Traditional Healers in Latin America There are numerous reasons why traditional healers are so widespread and commonly used in Latin America. One reason is purely economic as traditional healers are the only medical care many families could afford (Trotter & Chavira, 1997). Traditional healers in general do not take any money from their clients and definitely do not take anything from very poor clients.They could accept offerings for their service but it is done on case to case basis. So for that reason the most important economic reason why healers are used is because their services are free. Another reason why healers are so popular is religious. As it was described above in order to be a healer one has to have a gift from the high spiritual power (Trotter & Chavira, 1997). Healers often offer some sort of a mix of religious, spiritual and physical practices that resonate with the Latin American community that has this mix also present.Latin American culture is both spiritual and religious and this is exactly what healers do offer. The religious/spiritual aspect of healing process is something that is strikingly different from traditional medicine and this is why healers are so popular. They often use religious objects in practices and the healing process including icons, crucifixes and so on. Finally there is a social explanation for why traditional healers are so often used even today. Healers have been traditionally not just a part of community but very well respected and admired members of community.Latin American culture is well known for its strong cultural ties and strong community sense (Trotter & Chav ira, 1997). Hence in case of illness or any other malady the first reaction is to go to the community member, a traditional healer than to go the hospital which many could not afford anyway. Healers also offer social and spiritual support and often even counseling, thus making it even more likely for a person to seek their help. As it was discussed above, economic, religious and social reasons for using traditional healers are very strong and more often than not they operate in conjunction even further supporting each other.For example, when a person has no money, he is less likely to go to a hospital. A healer could also play into person’s religiosity and sense of community, so all this factors together make a traditional healer more popular than any local hospital. Conclusion Traditional healers have been and most likely will be in the foreseeable future a very important part of Latin American culture and way of life. Traditional healers operate within community and are imp ortant and well-respected members of the community.They are often the last resort for poor segments of population, and the complex interactions of social, religious and economic factors often make them more attractive and popular than local hospitals. Traditional healers often have specific specializations such as herbalists or midwives, but many have numerous specializations. Not anyone can be a healer as it requires a gift and extensive training. Traditional healers offer a variety of services including physical treatment, various remedies and amulets and spiritual and psychological counseling.Spirituality is important part of practice and is one component which makes healers so popular. Traditional healers’ approach differs significantly from traditional medicine approach because it is more multileveled and holistic. Healers in a sense try to address the issues on both physical and spiritual levels, while the traditional medicine often focuses on physical symptoms and defi nitely less on spiritual aspects of illness. Healers are of course often frown upon by the medical community and called â€Å"quack doctors† because they do not have formal training and education.Yet Latin American communities still use their services extensively and remarkably even immigrant communities like Mexicans in the US for example, still use traditional healers. Recent estimates demonstrated that as many as 75% of Latin Americans living in Texas used traditional healers in one way or the other to either completely or partially deal with their illnesses or ailments (Tafur, 2009). This trend is very unlikely to change any time soon, after all traditional healers have been a part of Latin American culture for thousands of years. References:Avila E (1999). Woman Who Glows in the Dark: A Curandera Reveals Traditional Aztec Secrets of Physical and Spiritual Health. New York: Penguin Putnam. Davidow J (1999). Infusions of Healing: A Treasury of Mexican-American Herbal Remed ies. New York: Simon & Schuster. Tafur, M. M. , Crowe, T. K. , & Torres, E. (2009). A review of curanderismo and healing practices among Mexicans and Mexican Americans. Occupational Therapy International, 16(1), 82-88. Trotter, R. T. , & Chavira, J. A. (1997). Curanderismo: Mexican American Folk Healing. University of Georgia Press.

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