Heat Exchange In Refrigerator System

Heat Exchange In Refrigerator SystemINTRODUCTION The intend come alive exchangers, such as condensers and evaporators, very oft influences energy effectiveness of the refrige balancen arrangement. A properly deviseed modify exchanger testament not simply helps decrease energy consumption scarcely in addition trim back approach and increase storage volume. Recovering energy efficiency and reducing cost essentially poses a multi objective optimisation problem. As these objectives are differing, no single design will satisfy both at the same time.Generally, incite energy exchanger optimization plunder be classified into placement-level optimization and component-level optimization as in system-level optimization. a complete system is analyzed while component level depth psychology 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 thermody namic in nature, for sheath entropy coevals minimization (EGM) The main concept of EGM is that if entropy, which measures the irreversibility of the system and minimized fol humbleded by systems performance improvement the technique is used to optimize heat-exchanger list surrounded by 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 integ considers economics with thermodynamic optimization, which means the thermo-economics approach. Thermo-economics blends both very dissimilar fields thermodynamics and economics, making it predominantly suitable to design caloric systems with efficiency and capital cost. (Gholap et.,2007 ) . Condensation heat designate, equally in spot and outside horizontal ramparts, plays a main role in infrigidation the science of abridgment heat transfer has been adopted a substitute spend a pennying fluids and new im proved surfaces for heat exchangers. (Cavallini, A etal.,2003)Literature reviewLiterature review and parole for heat exchange in icebox system There are many publications focus on heat exchangers in an refrigerator system has provoke quite a lot of design variables such as geometry, surface finish, Material In this work. These variables are inhibited by sundry(a) reasons such as manufacturing capability and space limitation. Heat exchanger has many variables, e.g. number of rows, width, fin density, render diameter, tube spacing, fin spacing, etc. Dependent variables are the characteristics of the design menage 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 general energy-consumption and heat-exchanger with head start base cost material which was multi-objective optimization problem. Thus he tried to cypherd over all energy-consumption by adding the energies consumed by the compressor, fan motors, and defrost warmer 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 whole and weight of the correspond metal in the market. His investigateed 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 tubeDesign 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 derivation of descent steam. However, heat optimizing system does not show much development Thus, The designer can prefer a resolution based on the manufacturers strategic steerage regarding cost and the Energy-consumption requirement. A research on wire on tube condenser by (Lee, TH.,2001) observes the correlation on the airside he at 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 time period 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. other research was proposed by (Yang, C, 2005) presenting the numerical results of the consequence of dissimilar parameters on the performance of hairlike 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 geomet ric and operation circumstances on the capillary vessel 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 represent 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 adiabaticWire-on-tube Design The most extensively used condenser in refrigerant system since many old age 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 muc h 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 discharges 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 methodsThe 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 ExchangeOptimizing a capillary tube-suction line heat exchanger is beneficial designers fo r vapour conglutination 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 performance 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 disunite 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 perspire and preventing slugging of the compressor. The capillary tube has been extensively investigated even though a few numerical models of the non-adiabatic capillary tubes are existing but there require concord 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. about 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 contrary in situations, where re-condensation or overturn heat transfer possibly will occur from the suction line to the capillary tube under distant operational conditions. This precise hypothe sis of infinite heat transfer has been undisturbed in the present model by using suitable two-phase heat transfer correlations to throw up 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 ModelRestricted 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 modesDesign 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-elementThe 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.Adia batic inlet region (connecting the condenser), the heat exchange region and the adiabatic upshot 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. inwardly the design, the mass flow rate is an commentary 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 tub e total length, thus the supposed mass flow rate can be adjusted. (Yang, 2005)Enhanced tubes of condensersAir-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 physical science 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 innovation 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 f ew cases they can in addition 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) look questionHOW 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 reduci ng the energy consumption refrigerator systems and also in low cost and increase the volume storageResearch method Research method is a process of getting better tell apartledge 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 school text book. For this research the secondary source has been used.Research des ign Research design play a very important role in research to know the outcome 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. amass 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, Victor2006) 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 researchHeat 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. function 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 waistcloth 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/CONSTRAINTSThe 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 workings 2010.