Genel enerji tasarrufu yönünden gemilerin ekonomik hızlarının tespiti
Prediction of economic speed of ships for general fuel saving
- Tez No: 39782
- Danışmanlar: PROF.DR. KEMAL KAYALI
- Tez Türü: Doktora
- Konular: Gemi Mühendisliği, Marine Engineering
- Anahtar Kelimeler: Enerji tasarrufu, Gemiler, Yakıt tüketimi, Energy saving, Ships, Fuel consumption
- Yıl: 1994
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: Belirtilmemiş.
Özet
ÖZET Bu çalışmada, öncelikle bir ticaret gemisinin olası çalışma ©artları içinde, çalışma hattı verileri, gemiye ait karakteristik veriler İle serbest piyasa koşullarında oluşan konjonktür el veriler saptanmış ve ya kabliledi lebi lir varsayımlar yapılmıştır. Böylece faktör veya parametreler için sağlıklı bir veri oluş turulmuş» veriler »tanımlanan fayda, yararlılık, en az kayıp veya en fazla kazanç bazındaki Ölçütlere göre değerlendirilerek ekonomik gemi hızı belirlenmiştir. Çalışmanın birinci bölümünde, ekonomik gemi hı zının belirlenmesinde kullanılan geleneksel tekno-eko- nomik ölçlitler ile günümüze değin yapılmış olan çalış maların özetleri ve değerlendirilmesi sunulmuştur. İkinci bölümde gemi hızının belli oranlarda a- zaltı İması veya artırılması sonucu gemi işletmeciliği nin en önemli maliyet öğesi olan yakıt sarfiyatının hangi dtlzeyde değişeceği hususunda bir takım bağıntı lar oluşturulup, örnek çözümler verilmiştir. UçtincU böltimde gemilerdeki tipik enerji balans ları belirtilerek, enerji tasarrufu açısından dizayn sürecinin genel bir değerlendirilmesi yapılmıştır. Dördüncü" bölümde, bir ticaret gemisinin olası çalışma koşulları içersinde isletme maliyetleri, yük arzı eksikliği veya diğer açılardan oluşabilen düşük doluluk oranlarında sefer düzenlenmesine bağlı olarak parametrelerdeki değişimlerin genel bir analizi yapıl mıştır. Böylece ekonomik gemi hızını belirleyen fak tör veya parametrelerin matematik modelinin çalışma koşullarına bağlı olarak belirlenmesi olanaklı hale getirilmiştir. Besinci bölümde ekonomik gemi hızı bir kavram olarak ele alınmış, dördüncü bölümdeki genellemeler yerine spesifik değerler göz önüne alınarak, bir ge minin ekonomik hızının bulunmasına örnek çözümler ve rilmiştir. Ayrıca, olası maliyet değişimleri veya var- sayımlardaki hataların bulunan sonuçları hangi düzeyde etkilediği CSensitivity Analysis) incelenerek sonuçla rın yeterliliğine açıklık getirilmiştir. Son bölümde ise ekonomik hızın belirlenmesi problemlerinin genel kritiği yapi-larak, varılan so nuçlar ve Öneriler sunulmuştur.
Özet (Çeviri)
PREDICTION OF ECONOMIC SPEED OF SHIPS FOR GENERAL FUEL SAVING SUMMARY This thesis consists of six chapters. In the first chapter economic criteria used in ship investment and ope rations are di fined and a summary of past studies are gi ven in a cronological order. Chapter 2 deals with the effect of ship speed on fuel economy which is the most important factor in ship operating. In general, a reduction in speed results in an increased voyage time, reduced annual cargo capacity and income, and reduced fuel consumpi ton. The results of analyses show that, for a reduction in ship speed by 1-15%, fuel saving ratio per centage can be calculated by using the following formula: 6V YTO =190 - Here, 6V is reduction in ship speed and V is the original speed value. For instance, when the ship speed is reduced by 10 %, fuel cost will be reduced by 19%. In the above formula, it is assumed that the Admiralty cons tant is constant for small values of 6V. Therefore this formula will not be valid for large values of <5V. In the third chapter a procedure to model fuel sav ings in a ship has-been developed. For diesel and steam eng'ined ships typical energy balances are specified and the areas where energy savings can be realised are iden tified. Basic criteria in the selection of a diesel en gine are specified and the positive influence of a good engine selection on fuel economy is emphasized. It is known that, fuel economy is not only dependent on engine selection but can also be improved by modifying hull form for better propulsive performance and a lighter vessel design. Chapter A deals with factors and parameters which affect economic ship speed and the relation between these parameters and fullness. These parameters are also defi ned analytically for possible operating conditions. Defi nitions of i ncome, expenditure, tax, and net profit are gi ven as well as the relations between them. In the fifth chapter, detailed definitions of fac tors and parameters which affect economic ship speed are given and profitability or least cost based criteria XIare formulated for a cargo ship. These criteria may have advantageous points or drawbacks with regard to each other. However, each criterion is useful i-n the assessment of the problem from different points of view. Therefore, instead of using single criterion, different criteria should be used and the results sould be compared. The following cri teria have been considered in this study: a) Annual Net Profit YNK = YNG - CYIMVO + A + YVM) b) Capital Recovery Factor YNG - CYIMVO + A + YVM) CRF = TGMD + C4.BGMF.BHP c) Required Freight Rate YIMVO + A + YVM RFR = CALFAG + ALFAD) CDWT. YSS. FR d) Rate of Cost/Income. YIMVO + A + YVM RCI = FR.YSS CALFAG + ALFAD) CDWT e) Cost per Ton Mile for a voyage time TV 8760 CYIMVO + A + YVM) CTM = 2R CALFAG + ALFAD) CDWT Here, YNG = YSS CALFAG + ALFAD) CDWT.FR Annual Freight income, & YSS : Annual number of trips. XIIYIMVO A YVM FR ALFAG ALFAD Q BGMF TV C4 Annual Operating Cost, before tax, 3 Depreciation, $ Annual tax cost, &. Freight Rate, $/ton. Cargo utilization factor, departure. Cargo utilization factor, arrival. Annual Cargo Capacity, ton. Engine cost per horse power, $/HP. Voyage time, hour. Constant It is known that, maximum points of YNK and CRF criteria, and minimum points of RFR, RCI an CTM criteria will represent the economic speed. Ship operating can be managed by hiring or owning. In the case of ship owner, the owner should envisage depreciation payments because of large investment. There seems to be less risk in ship hiring. Ship hiring should aim large profit in short term while the owner targets making profit in long term. Therefore, different problems will require different criteria. In general, YNK criterion for a large invest ment, CRF criterion for highest profit for the investment and RFR, RCI and CTM criteria for short term operating with small investment can be suggested. Traditional approaches to predict economic ship speed have been based on profitability or least cost. A choice between these two criteria depends upon the characteristics of ship operations and the targets of the owner. It is not possible to propose a single criterion which is valid for all cases. Ship operating needs to make profit hence it is important to optimise the speed and incorporate the design modifications which will maximise the profit. The speed is the most important factor which affects profitability. It can be said that in general, in general, the design modifications which lead to a reduction in operating costs should be made, the selection of the operating line should be made carefully and the optimum ship speed should be determined using an appropriate criterion. In this study CRF (Capital Recovery Factor) is assumed to be superior to the other criteria which define profitability and the ship speed predictions are based -on this criterion. Although there have been various attempts to define the profitability or revenue, these definitions are XIIIbasically very similar in nature. The main problems are to determine the characteristics of the ship and the ope rating line, to predict factors, parameters and constants which affect the problem using suitable methods, and to predict the economic ship speed using an appropriate criterion. This thesis differs from other studies in the following aspects: 1. In order to increase accuracy in modelling ship operations, voyage time and port time have been cor rected for the cases in which the ship is half laden. 2. Port time has been analysed mathematically for the different values of loading and unloading rates. The time required to load or unload 1 ton of cargo is defined as gCLR.UR) = LR + UR LR. UR The optimal values of LR and UR have been deter mined by considering all alternatives which satisfy LR + UR = A (constant). 3. In the design of the ship for various speeds engine power, engine rpm, propeller rpm and specific fuel consumption values will have different values. Thus in this study engine rpm, propeller rpm and specific fuel consumption have been related to engine power analytically. In ship operating sufficient and acceptable solutions are sought on the basis of profitability or least cost. However, it is well known that these techno-economic aproaches can only be reliable within limited and subjective conditions. An economic criterion which is widely accepted as reliable today may become arguable and insufficient after a while in environment where economic conditions vary. Thus it is difficult to propose a single rigid solution because of the changes in the time dimension of the parameters of the techno -economic problems. Furthermore there is no widely accepted single criterion. Different criteria adopted for different ship types and conditions have been given in Chapter 1. In literature, economic criteria may also be called objective function. Variables, parameters and constants XIV «which form this objective function can be predicted on basis of historical trend curves. Some other parameters such as FR CFreight rate) can be predicted by estimating future values. Naturally, there will be uncertainties in using values based on predictions for past and future for a problem needs to be solved at the present. As a result. solutions based on data prediction for future will always be arguable. It is not possible to determine an economic speed, using today's economic values and criteria, which will be valid in 5, 10 or even 15 years later. The problem is affected by many factors such as freight rate, competi tion, fuel costs and crew efficiency which change contin- ously. Hence it is obvious that the solution will be a function of time. These parameters can only be approxi mated as function of time using statistical data and probabilistic techniques. In the operating and design of ships there is a ne cessity to be satisfied with approximate solutions rather than those which are absolute and exact. The accuracy of the results will depend on how good the modelling of the problem is. XV
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