Pub Date : 2010-08-15DOI: 10.5545/132_DOI_NOT_ASSIGNED
N. Fain, N. Moes, J. Duhovnik
Within the knowledge-based economy several institutions are involved in product innovation processes. Literature study has shown that the most researched and cited are the industry-university-government relations, presented in the Triple Helix model of institutional relations within new product development (NPD). Based on a case study of the Academic Virtual Enterprise, we have put the sole input of these institutions in NPD into question. We have tested and supported the claim that the user and the society are equal partners in the product innovation process. We have put forward the Fourfold Helix model that features a new formation of institutional relations where special focus is placed on the involvement of the user and the society in NPD.
{"title":"The role of the user and the society in new product development","authors":"N. Fain, N. Moes, J. Duhovnik","doi":"10.5545/132_DOI_NOT_ASSIGNED","DOIUrl":"https://doi.org/10.5545/132_DOI_NOT_ASSIGNED","url":null,"abstract":"Within the knowledge-based economy several institutions are involved in product innovation processes. Literature study has shown that the most researched and cited are the industry-university-government relations, presented in the Triple Helix model of institutional relations within new product development (NPD). Based on a case study of the Academic Virtual Enterprise, we have put the sole input of these institutions in NPD into question. We have tested and supported the claim that the user and the society are equal partners in the product innovation process. We have put forward the Fourfold Helix model that features a new formation of institutional relations where special focus is placed on the involvement of the user and the society in NPD.","PeriodicalId":237575,"journal":{"name":"Strojniški vestnik","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127458349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-06-15DOI: 10.5545/115_DOI_NOT_ASSIGNED
M. Muhič, J. Tušek, F. Kosel, D. Klobčar
This paper deals with defects produced in aluminium alloy die casting dies during die operation. The most frequent defect is thermal fatigue cracking. Hardness and toughness is measured on specimens cut from different parts of used die casting die. The results show a significant difference in material microstructure and hardness between the surface and the core. The intense martensite tempering is observed on the die surface, while the core material microstructure remains unchanged. A considerable hardness drop is measured on the material surface and no change is observed in the depth of six millimetres from surface.
{"title":"Analysis of Die Casting Tool Material","authors":"M. Muhič, J. Tušek, F. Kosel, D. Klobčar","doi":"10.5545/115_DOI_NOT_ASSIGNED","DOIUrl":"https://doi.org/10.5545/115_DOI_NOT_ASSIGNED","url":null,"abstract":"This paper deals with defects produced in aluminium alloy die casting dies during die operation. The most frequent defect is thermal fatigue cracking. Hardness and toughness is measured on specimens cut from different parts of used die casting die. \u0000The results show a significant difference in material microstructure and hardness between the surface and the core. The intense martensite tempering is observed on the die surface, while the core material microstructure remains unchanged. A considerable hardness drop is measured on the material surface and no change is observed in the depth of six millimetres from surface.","PeriodicalId":237575,"journal":{"name":"Strojniški vestnik","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134623603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-05-15DOI: 10.5545/111_DOI_NOT_ASSIGNED
Arijan Abrashi, N. Štefanić, D. Lisjak
In this paper we proposed and tested a niching genetic algorithm (GA), which for comparison of individuals in the population uses so-called Hamilton similarity. The advantage of the Hamilton similarity lies in the fact that there is no need for context sensitive information in order to successfully compare two population members. Furthermore, the algorithm was tested on the famous Job Shop Scheduling Problem (JSSP) - benchmark mt10, and statistical results of the test were given. Significantly smaller standard deviation of the proposed GA compared to Simple GA clearly demonstrates its superiority. In addition to the Hamilton similarity, time dependent fitness scaling was proposed which in conjunction with niching significantly reduces the probability of the algorithm to get stuck in one of the less desirable local optimum. Finally, suggestions for future research are given.
{"title":"Solving JSSP by Introducing Hamilton Similarity and Time Dependent Fitness Scaling","authors":"Arijan Abrashi, N. Štefanić, D. Lisjak","doi":"10.5545/111_DOI_NOT_ASSIGNED","DOIUrl":"https://doi.org/10.5545/111_DOI_NOT_ASSIGNED","url":null,"abstract":"In this paper we proposed and tested a niching genetic algorithm (GA), which for comparison of individuals in the population uses so-called Hamilton similarity. The advantage of the Hamilton similarity lies in the fact that there is no need for context sensitive information in order to successfully compare two population members. Furthermore, the algorithm was tested on the famous Job Shop Scheduling Problem (JSSP) - benchmark mt10, and statistical results of the test were given. Significantly smaller standard deviation of the proposed GA compared to Simple GA clearly demonstrates its superiority. \u0000In addition to the Hamilton similarity, time dependent fitness scaling was proposed which in conjunction with niching significantly reduces the probability of the algorithm to get stuck in one of the less desirable local optimum. Finally, suggestions for future research are given.","PeriodicalId":237575,"journal":{"name":"Strojniški vestnik","volume":"7 14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127975722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-04-15DOI: 10.5545/99_DOI_NOT_ASSIGNED
Ellen Bergseth, S. Björklund
Gear tooth modifications, such as lead crowning, are often recommended to compensate for misalignment (e.g. assembly deviations). Lead crowning means that the tooth centre is slightly thicker than ...
齿轮齿的修改，如铅冠，通常建议补偿不对准(如装配偏差)。铅冠意味着牙齿中心比…
{"title":"Logarithmical Crowning for Spur Gears","authors":"Ellen Bergseth, S. Björklund","doi":"10.5545/99_DOI_NOT_ASSIGNED","DOIUrl":"https://doi.org/10.5545/99_DOI_NOT_ASSIGNED","url":null,"abstract":"Gear tooth modifications, such as lead crowning, are often recommended to compensate for misalignment (e.g. assembly deviations). Lead crowning means that the tooth centre is slightly thicker than ...","PeriodicalId":237575,"journal":{"name":"Strojniški vestnik","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115589892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-02-15DOI: 10.5545/90_DOI_NOT_ASSIGNED
T. Kek, J. Grum
The paper presents the results of the research of a laser surface hardening process applied to the C45E steel with graphite absorber coating on specimen surfaces. The evaluation of the laser surface hardening process was performed by measuring the IR radiation from the interaction spot. The results confirmed a strong correlation between the IR radiation voltage signal and the dimensions of microstructural changes occuring in the laser surface hardening steel. Changes of the absorbing coating thickness produced changes of the absorptivity of the laser beam, which was confirmed by measurements of the depth and width of hardened traces. For laser surface hardening the optimum coating thickness of a graphite absorber was determined. A factorial analysis and a method of orthogonal polynomials were used to determine response surfaces for the voltage signal of IR radiation the depth and width of the hardened trace achieved. Absorptivity difference between various graphite absorber coating thicknesses was evaluated based on the Ashby-Shercliff model.
{"title":"Influence of the Graphite Absorber During Laser Surface Hardening","authors":"T. Kek, J. Grum","doi":"10.5545/90_DOI_NOT_ASSIGNED","DOIUrl":"https://doi.org/10.5545/90_DOI_NOT_ASSIGNED","url":null,"abstract":"The paper presents the results of the research of a laser surface hardening process applied to the C45E steel with graphite absorber coating on specimen surfaces. The evaluation of the laser surface hardening process was performed by measuring the IR radiation from the interaction spot. The results confirmed a strong correlation between the IR radiation voltage signal and the dimensions of microstructural changes occuring in the laser surface hardening steel. \u0000Changes of the absorbing coating thickness produced changes of the absorptivity of the laser beam, which was confirmed by measurements of the depth and width of hardened traces. For laser surface hardening the optimum coating thickness of a graphite absorber was determined. A factorial analysis and a method of orthogonal polynomials were used to determine response surfaces for the voltage signal of IR radiation the depth and width of the hardened trace achieved. Absorptivity difference between various graphite absorber coating thicknesses was evaluated based on the Ashby-Shercliff model.","PeriodicalId":237575,"journal":{"name":"Strojniški vestnik","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128401823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-01-15DOI: 10.5545/78_DOI_NOT_ASSIGNED
A. Polajnar, M. Leber, N. V. Herzog
The paper describes the adjustment of the sewing workstation with respect to working postures and workers’ perceptions based on the results of a survey research carried out in 32 sewing workstations in different garment production factories in Slovenia. Poor posture of the trunk, neck and upper extremities, and the monotonous repetitive movements result in a high prevalence of musculoskeletal complaints affecting back, neck and upper extremities among sewing machine operators. Several studies have confirmed that working postures are still a common problem in garment industry and ergonomically designed workstations can considerably reduce the above-mentioned problems. Therefore, the main purpose of the paper is to formulate all ergonomic recommendations for the modification of sewing machine workstations .
{"title":"Muscular-Skeletal Diseases Require Scientifically Designed Sewing Workstations","authors":"A. Polajnar, M. Leber, N. V. Herzog","doi":"10.5545/78_DOI_NOT_ASSIGNED","DOIUrl":"https://doi.org/10.5545/78_DOI_NOT_ASSIGNED","url":null,"abstract":"The paper describes the adjustment of the sewing workstation with respect to working postures and workers’ perceptions based on the results of a survey research carried out in 32 sewing workstations in different garment production factories in Slovenia. Poor posture of the trunk, neck and upper extremities, and the monotonous repetitive movements result in a high prevalence of musculoskeletal complaints affecting back, neck and upper extremities among sewing machine operators. \u0000Several studies have confirmed that working postures are still a common problem in garment industry and ergonomically designed workstations can considerably reduce the above-mentioned problems. Therefore, the main purpose of the paper is to formulate all ergonomic recommendations for the modification of sewing machine workstations .","PeriodicalId":237575,"journal":{"name":"Strojniški vestnik","volume":"85 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114012153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-01-15DOI: 10.5545/75_DOI_NOT_ASSIGNED
L. Lugaric, Ljubomir Majdandzic, D. Skrlec
In this paper, choosing appropriate locations for household solar water heating systems within a country is based on assessing project feasibility by using solar irradiation integrated in a geographical information system (GIS) and investment risk analysis, based on uncertainties in project input variables. Current indicators and statistics of solar systems of EU and Croatia are given, followed by impacting factors on investments in domestic SWH. Investment risks are determined. GIS is constructed to assess solar irradiation potential on a countrywide scale. A spreadsheet model for financial analysis using the Monte Carlo method for probabilistic simulation of uncertain project parameters is shown, which integrates GIS and determines a financial feasibility for two case studies. Financial indicators of net present value (NPV), internal rate of return (IRR) and simple payback time (SPB) are shown for three investment strategies, varying in financial resources according to profiled income categories of households in the country. A sensitivity analysis has been performed to determine the impact of individual risks on the financial outcome of the project. Financial flows are compared to determine the difference in feasibility for the same project on two different locations. Probability distributions for risks and financial indicators are shown.
{"title":"Countrywide Positioning of Domestic Solar Water Heating Systems using Risk Analysis and Geographical Information System","authors":"L. Lugaric, Ljubomir Majdandzic, D. Skrlec","doi":"10.5545/75_DOI_NOT_ASSIGNED","DOIUrl":"https://doi.org/10.5545/75_DOI_NOT_ASSIGNED","url":null,"abstract":"In this paper, choosing appropriate locations for household solar water heating systems within a country is based on assessing project feasibility by using solar irradiation integrated in a geographical information system (GIS) and investment risk analysis, based on uncertainties in project input variables. Current indicators and statistics of solar systems of EU and Croatia are given, followed by impacting factors on investments in domestic SWH. Investment risks are determined. GIS is constructed to assess solar irradiation potential on a countrywide scale. A spreadsheet model for financial analysis using the Monte Carlo method for probabilistic simulation of uncertain project parameters is shown, which integrates GIS and determines a financial feasibility for two case studies. Financial indicators of net present value (NPV), internal rate of return (IRR) and simple payback time (SPB) are shown for three investment strategies, varying in financial resources according to profiled income categories of households in the country. A sensitivity analysis has been performed to determine the impact of individual risks on the financial outcome of the project. Financial flows are compared to determine the difference in feasibility for the same project on two different locations. Probability distributions for risks and financial indicators are shown.","PeriodicalId":237575,"journal":{"name":"Strojniški vestnik","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125899384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A numerical simulation for a filling process in an open tank is performed in this paper. A single set of governing equations is employed for the entire physical domain covering both water and air regions. The great density jump and the surface tension existing at the free surface are properly handled with the extended weighting function scheme and the NAPPLE algorithm. There is no need to smear the free surface. Through the use of a properly defined boundary condition, the method of "extrapolated velocity" is seen to provide accurate migrating velocity for the free surface, especially when the water front hits a comer or a vertical wall. Such a methodology does not pose to the Courant criterion, and thus allows large time steps. The numerical results show that when the water impinges upon a comer, a strong pressure gradient forms in the vicinity of the stagnation point. This forces the water to move upward along the vertical wall. The water eventually falls down and generates a gravity wave. These findings are seen to excellently agree with an existing experiment for the free surface evolution and the corresponding total water volume inside the tank. Due to its accuracy and simplicity, the present numerical method is believed to have good performances for simulating viscous free surface flow in industrial and environmental problems such as die-casting, cutting with water jet, gravity wave on sea surface, and many others.
{"title":"Filling process in an open tank","authors":"Shong-Leih Lee, S. Sheu","doi":"10.1115/1.1624425","DOIUrl":"https://doi.org/10.1115/1.1624425","url":null,"abstract":"A numerical simulation for a filling process in an open tank is performed in this paper. A single set of governing equations is employed for the entire physical domain covering both water and air regions. The great density jump and the surface tension existing at the free surface are properly handled with the extended weighting function scheme and the NAPPLE algorithm. There is no need to smear the free surface. Through the use of a properly defined boundary condition, the method of \"extrapolated velocity\" is seen to provide accurate migrating velocity for the free surface, especially when the water front hits a comer or a vertical wall. Such a methodology does not pose to the Courant criterion, and thus allows large time steps. The numerical results show that when the water impinges upon a comer, a strong pressure gradient forms in the vicinity of the stagnation point. This forces the water to move upward along the vertical wall. The water eventually falls down and generates a gravity wave. These findings are seen to excellently agree with an existing experiment for the free surface evolution and the corresponding total water volume inside the tank. Due to its accuracy and simplicity, the present numerical method is believed to have good performances for simulating viscous free surface flow in industrial and environmental problems such as die-casting, cutting with water jet, gravity wave on sea surface, and many others.","PeriodicalId":237575,"journal":{"name":"Strojniški vestnik","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127490012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-07-01DOI: 10.1615/ICHMT.2000.THERSIEPROCVOL2THERSIEPROCVOL1.70
D. Didion, J. S. Brown
The advent of the global warming crisis has brought about a viewpoint, in many governments, that the halogen family of refrigerants should be replaced, in part or in toto, by the socalled natural refrigerants. For this proposal to be valid it is necessary to consider both the refrigerant's direct environmental impact and its life-long performance under field conditions. This is particularly true in the case of global warming because, for most applications, it is the heat pump's operating efficiency and its impact on the central power plant's emissions that is the dominating environmental factor. Any refrigerant must also meet a variety of other criteria that deal with durability, safety and costs. A simple comparison of basic fluid properties is conducted to indicate what system design considerations must be made if a refrigerant is to become an acceptable alternative. It is also reasoned that while computer models and laboratory prototypes are a necessary beginning, they are not sufficient to determine the true environmental impact of any system. Finally, the question is raised as to whether the refrigerant specification approach is the better path to an improved environment or if it is wiser to leave all options open for researchers and manufacturers to meet an environmental performance standard any way they choose.
{"title":"Challenges in developing environmentally safe heat pumping systems","authors":"D. Didion, J. S. Brown","doi":"10.1615/ICHMT.2000.THERSIEPROCVOL2THERSIEPROCVOL1.70","DOIUrl":"https://doi.org/10.1615/ICHMT.2000.THERSIEPROCVOL2THERSIEPROCVOL1.70","url":null,"abstract":"The advent of the global warming crisis has brought about a viewpoint, in many governments, that the halogen family of refrigerants should be replaced, in part or in toto, by the socalled natural refrigerants. For this proposal to be valid it is necessary to consider both the refrigerant's direct environmental impact and its life-long performance under field conditions. This is particularly true in the case of global warming because, for most applications, it is the heat pump's operating efficiency and its impact on the central power plant's emissions that is the dominating environmental factor. Any refrigerant must also meet a variety of other criteria that deal with durability, safety and costs. A simple comparison of basic fluid properties is conducted to indicate what system design considerations must be made if a refrigerant is to become an acceptable alternative. It is also reasoned that while computer models and laboratory prototypes are a necessary beginning, they are not sufficient to determine the true environmental impact of any system. Finally, the question is raised as to whether the refrigerant specification approach is the better path to an improved environment or if it is wiser to leave all options open for researchers and manufacturers to meet an environmental performance standard any way they choose.","PeriodicalId":237575,"journal":{"name":"Strojniški vestnik","volume":"53 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132026649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1615/ICHMT.2000.THERSIEPROCVOL2.60
Selis Onel, G. Guruz
The Yankee-Hood dryer is the crucial section of the paper machine due to the consumption of energy. As a consequence of continuously increasing energy costs, determination of the proper operating conditions is essential to operate the tissue machine in the most efficient and economic means while ensuring paper quality. The objective of this study is to evaluate the Yankee-Hood dryer in Ipekkagit' tissue paper factory, set the mass and energy balances and make optimization studies in order to achieve the desired production rate whilst keeping the drying parameters within limits at the minimum energy costs. The approach to solve the problem is to develop a steady state analytical model. The complicated drying system is simplified as the overall and sub systems. Material and energy balances are set up for each system. Data of machine parameters at several paper grades are collected at the factory during production. Material and energy balance equations are solved with the available data for the unknown parameters and for the determination of the drying parameters most effective on energy consumption. The critical drying parameters are air supply velocity, wet- and dry-hood temperatures, steam pressure in cylinder and exhaust humidity. Efficiency, defined as the ratio of energy required to evaporate the water to energy input through the system boundaries, is calculated as 28-30% for different grades of tissue paper production., Steady state rate of heat transfer to the wet sheet is analyzed considering the two-way mechanism, from steam through the cast iron shell and from heated air. The transfer of heat is eased in both mechanisms by the lightweight tissue paper that has a comparatively lower internal thermal resistance with respect to other types of paper products. Steam side is modeled considering different thermal resistances in series: Condensate layer, shell, shell-sheet contact, and paper sheet. These resistances are to the same order of magnitude, cast iron shell being the largest and paper sheet the smallest in value. Sheet-shell contact heat transfer coefficient is strongly dependent on sheet moisture content that is assumed to vary almost linearly due to the angular position on the Yankee. Air side heat transfer is mostly affected by the temperature, humidity and velocity of the air that is blown on to the sheet. Calculations resulted out that rate ofheat transfer from air side is 55-65% while that from steam side is 35-45% of their total indicating the dominance of air side on drying.
{"title":"Energy optimization of the Yankee-Hood dryer","authors":"Selis Onel, G. Guruz","doi":"10.1615/ICHMT.2000.THERSIEPROCVOL2.60","DOIUrl":"https://doi.org/10.1615/ICHMT.2000.THERSIEPROCVOL2.60","url":null,"abstract":"The Yankee-Hood dryer is the crucial section of the paper machine due to the consumption of energy. As a consequence of continuously increasing energy costs, determination of the proper operating conditions is essential to operate the tissue machine in the most efficient and economic means while ensuring paper quality. The objective of this study is to evaluate the Yankee-Hood dryer in Ipekkagit' tissue paper factory, set the mass and energy balances and make optimization studies in order to achieve the desired production rate whilst keeping the drying parameters within limits at the minimum energy costs. The approach to solve the problem is to develop a steady state analytical model. The complicated drying system is simplified as the overall and sub systems. Material and energy balances are set up for each system. Data of machine parameters at several paper grades are collected at the factory during production. Material and energy balance equations are solved with the available data for the unknown parameters and for the determination of the drying parameters most effective on energy consumption. The critical drying parameters are air supply velocity, wet- and dry-hood temperatures, steam pressure in cylinder and exhaust humidity. Efficiency, defined as the ratio of energy required to evaporate the water to energy input through the system boundaries, is calculated as 28-30% for different grades of tissue paper production., Steady state rate of heat transfer to the wet sheet is analyzed considering the two-way mechanism, from steam through the cast iron shell and from heated air. The transfer of heat is eased in both mechanisms by the lightweight tissue paper that has a comparatively lower internal thermal resistance with respect to other types of paper products. Steam side is modeled considering different thermal resistances in series: Condensate layer, shell, shell-sheet contact, and paper sheet. These resistances are to the same order of magnitude, cast iron shell being the largest and paper sheet the smallest in value. Sheet-shell contact heat transfer coefficient is strongly dependent on sheet moisture content that is assumed to vary almost linearly due to the angular position on the Yankee. Air side heat transfer is mostly affected by the temperature, humidity and velocity of the air that is blown on to the sheet. Calculations resulted out that rate ofheat transfer from air side is 55-65% while that from steam side is 35-45% of their total indicating the dominance of air side on drying.","PeriodicalId":237575,"journal":{"name":"Strojniški vestnik","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125542013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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