Peilin Zhou

A modified quasi-dimensional multi-zone combustion model for direct injection diesels

Abstract A quasi-dimensional multi-zone combustion model for direct injection diesel engines has been developed and subsequently evaluated using test results from a PA6 engine. In the new model, fuel spray is divided into a number of zones, which are treated as open thermodynamic systems exchanging mass and energy with the surrounding air. This paper pays particular attention to the fuel evaporation process whereby a detailed evaporation model is developed to predict the fuel evaporation rate. The effects of both collision and aggregation of fuel droplets have been included in the fuel evaporation mechanism. The theory of grouping of fuel droplets and interference areas among droplets is used to gain more accurate fuel evaporating and burning rates for the engine. The results from the simulation studies have shown good agreement with the measurements from the experimental engine. In-cylinder pressure and temperature are given particular attention in this study. The developments reported in this paper lead to a better understanding of the underlying physical mechanisms and the effects of various parameters on engine combustion. This work also presents a methodology for the development of a reliable but simple multi-zone model. Conclusions have been reached that the developed model is able to predict the rate of heat release and engine performance with a high accuracy.

Cutting tool operational reliability prediction based on acoustic emission and logistic regression model

Working status of cutting tools (CTs) is crucial to the products’ precision. If broken down, it may lead to waste product. Condition monitoring and life prediction are beneficial to the manufacturing process. In this research, Logistic regression models (LRMs) and acoustic emission (AE) signal are used to evaluate reliability. Based on different conditions estimation, CTs are investigated to determine the best maintenance time. Based on experimental data analysis, AE and cutting force signals have better linear relationship with CT wearing process. They can be used to demonstrate CT degradation process. Frequency band energy is determined as characteristic vector for AE signal using wavelet packet decomposition. Two reliability estimation models are constructed based on cutting force and AE signals. One uses both signals, while the other uses only AE signal. The reliability degree can be estimated using the two models, independently. AE feature extraction and LRM can effectively estimate CT conditions. As it is difficult to monitor cutting force in a practical working condition, it is an effective method for CT reliability analysis by the combination of AE and LRM method. Experimental investigation is used to verify the effectiveness of this method.

Development of a 3D Dynamic Programming Method for Weather Routing

This paper presents a novel forward dynamic programming method for weather routing to minimize ship fuel consumption during a voyage. Compared with the traditional two dimensional dynamic programming (2DDP) methods which only optimize the ship’s heading, while the engine power or propeller rotation speed are set as a constant throughout the voyage, this new method considers both the ship power setting and heading control. A float state technique is used to reduce the iteration on the process of optimization for computing time saving. This new method could lead to real global-optimal routing in comparison with traditional weather routing method which results in sub-optimal routing.

Pattern Recognition on Diesel Engine Working Conditions by Wavelet Kullback-Leibler Distance Method

Abstract This article introduces a novel pattern recognition and fault diagnosis method for diesel engines. The method is developed from engine vibration signal analysis in combination with wavelet and Kullback-Leibler distance (KLD) approaches. The new approach is termed wavelet Kullback-Leibler distance (WKLD). Experimental data relating to piston and cylinder liner wear obtained from a production diesel engine are used to evaluate the newly developed method. A good agreement between the experimental data and the WKLD estimation is found. The results of this article suggest that WKLD is an advancement on the methods which have been currently developed for pattern recognition and fault diagnosis of diesel engines.

Fouling release coating application as an environmentally efficient retrofit : a case study of a ferry-type ship

Purpose and methodsThe paper introduces a simple retrofit performed on a case study vessel, with the aim of assessing the retrofit’s potential environmental impacts via doing a life cycle assessment. Additionally, the case presented herein strives to evidence the applicability of life cycle assessment (LCA) appraisals within shipyard representatives or managers.Results and discussionThe environmental results shown in this paper are related to cost calculations presented for the selected retrofit, underlining the potential environmental impacts from the retrofit, while appraising its economic performance.ConclusionsThe paper strives to evidence that significant savings with regard to fuel costs can be achieved by the application of this retrofit to ships with a similar operational profile, but more importantly, the improved operational efficiency and the emission reductions can be noteworthy. Lastly, the results summarised intend to offer an optimistic context towards the implementation of the retrofit at a larger scale, i.e. a section of the existing fleet.

Fault diagnosis of a diesel engine by using the analysis of instantaneous angular speed with a flexible model

Engine shaft instantaneous angular speed (IAS) can be used to diagnose combustion related faults and other faults affecting the output of engines, especially for small-scale diesel generators. Unfortunately, it is difficult to apply this technology to monitoring the operational condition of a marine propulsion diesel engine due to its complex shafting systems and multiple factors affecting the shafting torsional vibration. In this paper, the characteristics of fault detection based on traditional IAS analysis methods are firstly analysed. A novel method has been developed based on treating the engine shaft system as a flexible model, aiming to extend the IAS technique to monitor the working condition of a large marine diesel engine. Theoretical studies and engine evaluation tests have been conducted on a marine diesel engine experiment set-up. It is shown that an integration of the developed flexible model with traditional IAS technique is feasible and accurate.

A feasibility study of the use of biodiesel in recreational boats in the UK

The paper presents a feasibility study for applying biodiesel in recreational boats in the United Kingdom for the purpose of rational utilization of energy resources and environmental protection. Biodiesel has been widely used to fuel diesel engines for onshore vehicles, particularly for agriculture machinery. Application of biodiesel for merchant ship propulsion on a large scale has been seen as not an option in the near future due to the lack of availability and supply chains of the fuel. However, there has been interest in the possibility of powering recreational boats with biodiesel in order to pursue marine environmental protection. The study reviews the current status of using biodiesel in recreational boats and analyses the market in the United Kingdom. Results on fuel availability for the sector, economic aspects and environmental benefits are presented.

Evaluation of safety exclusion zone for LNG bunkering station on LNG-fuelled ships

ABSTRACT With increasing interests in using LNG as a marine fuel, safety issues for LNG bunkering have brought about global discussion on establishing a safety exclusion zone around LNG bunkering areas. However, international consensus has yet to be reached in determining an appropriate extent of the zone to ensure safe liquefied natural gas (LNG) bunkering. The purpose of this study is to identify potential risks of LNG bunkering and to present a statistical method for determining the safe exclusion zone around LNG bunkering station with the help of a purpose-built computer program, integrated quantitative risk assessment (IQRA). A probabilistic risk assessment approach was adopted in this study to determine the safety exclusion zone for two case ships: one, a 300,000 DWT very large ore carrier (VLOC) and the other a 32,000 DWT bulk carrier. The results are then compared with those obtained by a deterministic approach and the discrepancies are discussed. It was found from this study that the frequency of bunkering is one of the key factors in determining the extent of safety exclusion zone. Thus, a somewhat surprising result of 36 m radius safety exclusion zone for the 32,000 DWT bulk carrier compared to 6.4 m radius for the 300,000 DWT VLOC was obtained. It was also found that the deterministic approach produced a much more extensive safety exclusion zone for the 300,000 DWT VLOC subjected to infrequent large-scale LNG bunkering operations compared to the probabilistic approach, while it was reasonably consistent with the probabilistic approach for the 32,000 DWT bulk carrier which uses frequent small-scale bunkering.

An investigation into machine pattern recognition based on time-frequency image feature extraction using a support vector machine:

Abstract In this article, a new method of pattern recognition for machine working conditions is presented that is based on time-frequency image (TFI) feature extraction and support vector machines (SVMs). In this study, the Hilbert time-frequency spectrum (HTFS) is used to construct TFIs because of its good performance in non-stationary and non-linear signal analysis. Cyclostationarity signal analysis is a pre-processing method for improving the performance of the HTFS in the construction of TFIs. Feature extraction for TFIs is investigated in detail to construct a feature vector for pattern recognition. Gravity centre and information entropy of TFIs are used to construct the feature vector for pattern recognition. SVMs are used for different working conditions classification by the constructed feature vector because of its powerful performance even for small samples. In the end, rolling bearing pattern recognition is used as an example to testify the effectiveness of this method. According to the result analysis, it can be concluded that this method will contribute to the development of preventative maintenance.

Pattern recognition on diesel engine working condition by using a novel methodology - Hilbert spectrum entropy

In this paper, a novel method of diesel engine pattern recognition is introduced. Hilbert spectrum (HS) and information entropy are combined to form the Hilbert spectrum entropy (HSE) which is able to give an accurate entropy estimation for Hilbert spectrum. It is more convenient and visual to pattern recognition and fault diagnosis. Experimental data of piston and cylinder liner wear rates obtained from a production diesel engine is used to evaluate the newly developed method. A good conclusion has been reached. Hilbert spectrum entropy is a more advanced method, owing to its numerical outputs, for pattern recognition and fault diagnosis of diesel engines.