An Experimental Study on the Effect of Premixed and Equivalence Ratios on CO and HC Emissions of Dual Fuel HCCI Engine

In this study, effects of premixed and equivalence ratios on CO and HC emissions of a dual fuel HCCI engine are investigated. Tests were conducted on a single-cylinder engine with compression ratio of 17.5. Premixed gasoline is provided by a carburetor connected to intake manifold and equipped with a screw to adjust premixed air-fuel ratio, and diesel fuel is injected directly into the cylinder through an injector at pressure of 250 bars. A heater placed at inlet manifold is used to control the intake charge temperature. Optimal intake charge temperature results in better HCCI combustion due to formation of a homogeneous mixture, therefore, all tests were carried out over the optimum intake temperature of 110-115 ºC. Timing of diesel fuel injection has a great effect on stratification of in-cylinder charge and plays an important role in HCCI combustion phasing. Experiments indicated 35 BTDC as the optimum injection timing. Varying the coolant temperature in a range of 40 to 70 ºC, better HCCI combustion was achieved at 50 ºC. Therefore, coolant temperature was maintained 50 ºC during all tests. Simultaneous investigation of effective parameters on HCCI combustion was conducted to determine optimum parameters resulting in fast transition to HCCI combustion. One of the advantages of the method studied in this study is feasibility of easy and fast transition of typical diesel engine to a dual fuel HCCI engine. Results show that increasing premixed ratio, while keeping EGR rate constant, increases unburned hydrocarbon (UHC) emissions due to quenching phenomena and trapping of premixed fuel in crevices, but CO emission decreases due to increase in CO to CO2 reactions

Robust Truck Transit Time Prediction through GPS Data and Regression Algorithms in Mixed Traffic Scenarios

To enhance safety and efficiency in mixed traffic scenarios, it is crucial to predict freight truck traffic flow accurately. Issues arise due to the interactions between freight trucks and passenger vehicles, leading to problems like traffic congestion and accidents. Utilizing data from the Global Positioning System (GPS) is a practical method to enhance comprehension and forecast the movement of truck traffic. This study primarily focuses on predicting truck transit time, which involves accurately estimating the duration it will take for a truck to travel between two locations. Precise forecasting has significant implications for truck scheduling and urban planning, particularly in the context of cross-docking terminals. Regression algorithms are beneficial in this scenario due to the empirical evidence confirming their efficacy. This study aims to achieve accurate travel time predictions for trucks by utilizing GPS data and regression algorithms. This research utilizes a variety of algorithms, including AdaBoost, GradientBoost, XGBoost, ElasticNet, Lasso, KNeighbors, Linear, LinearSVR, and RandomForest. The research provides a comprehensive assessment and discussion of important performance metrics, including Mean Squared Error (MSE), Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), and R-squared (R2). Based on our research findings, combining empirical methods, algorithmic knowledge, and performance evaluation helps to enhance truck travel time prediction. This has significant implications for logistical efficiency and transportation dynamics

The use of air-bottoming cycle as a heat source for the carbon dioxide capture installation of a coal-fired power unit

The installations of CO2 capture from flue gases using chemical absorption require a supply of large amounts of heat into the system. The most common heating medium is steam extracted from the cycle, which results in a decrease in the power unit efficiency. The use of heat needed for the desorption process from another source could be an option for this configuration. The paper presents an application of gas-air systems for the generation of extra amounts of energy and heat. Gas-air systems, referred to as the air bottoming cycle (ABC), are composed of a gas turbine powered by natural gas, air compressor and air turbine coupled to the system by means of a heat exchanger. Example configurations of gas-air systems are presented. The efficiency and power values, as well as heat fluxes of the systems under consideration are determined. For comparison purposes, the results of modelling a system consisting of a gas turbine and a regenerative exchanger are presented