Abstract

In this study, the spray characteristics of kerosene were investigated by comparing with diesel. The spray characteristics including spray penetration, spray velocity and spray angle were investigated. The engine combustion characteristics were also investigated based on a diesel engine. The result shows that the injection durations for kerosene are longer than diesel due to the lower value of viscosity in kerosene. Kerosene has shorter spray penetration and lower spray velocity compared with diesel, while the spray angle of kerosene is larger than diesel. Compared with diesel, the engine has higher break thermal efficiency fueled with kerosene, while the NO emission is not increased much.

Abstract

Air Source Heat Pump (ASHP) system serves as a highly reliable system with long lifespan might be an available heat source for traditional Chinese Kang, which would solve the problem of waste pollution from a traditional Chinese fire Kang as well as keep the original advantages of Chinese Kang, such as localized heating and uniform airflow distribution. Based on this assumption, a novel system called bed-based heating system powered by ASHP was proposed. To prove the feasibility of the novel system and find out the difference of thermal performance to conventional heating system, this paper set up computational fluid dynamics (CFD) models for the novel system to find out the suitable covering bedding materials settings, then make comparison with traditional convection-based system. According to simulated results, the novel system have better thermal performance than convection-based system, such as moderate airflow(less than 0.1m/s) and good thermal comfort(ADPI:80%), but the case with 5mm cotton mattress and 15mm quilt may be not be suitable for the novel system to provide satisfied thermal comfort. Therefore, finding suitable covering bedding materials to improve the comfort and optimize the novel system would be the further work.

Abstract

Centralized power generation of the integrated electric propulsion enables various optimization techniques to automatically activate diesel generators to respond the load changes in an optimal manner. In this study, the power generation scheduling problem is formulated with constraints for a large cruise ship. The problem is solved with assistance of SFC modelling by three recent metaheuristic optimization methods, namely grey wolf optimizer, ant lion optimizer and whale optimization algorithm. Simulation results demonstrate the proposed methods ensure minimum fuel consumption compared with baseline data for certain load profiles.

Abstract

Regarding some serious problems like the energy crisis and environmental issues associated with the conventional compression refrigeration system, thermal refrigeration systems were therefore developed to overcome the mentioned problems. In this study, a completely novel integrated adsorption and absorption (AD-AB) refrigeration system driven by a low-grade heat source is proposed. Of importance, this novel cycle focuses on the inherent characteristics of the adsorption and absorption phenomena in the system. The innovation here is that the generator of the absorption cycle becomes the evaporator of the adsorption cycle. Therefore, the generation and evaporating pressure is no longer determined by the cooling and chilled water temperatures and the pressure is associated with the heat source temperature. This results in a new phenomenon of absorption, adsorption and the coupling of generation of solution and adsorption of refrigerant. The results reveal that the system enjoys a considerable high COP when a low-grade heat source is available.

Abstract

The presence of the amorphous phases has a great effect on the pozzolanic, chemical and mechanical properties of combustion by-products. Traditional quantitative phase identification of combustion by-products by the Rietveld refinement method fails to consider the presence of the amorphous and unidentified phases. Several direct and indirect analytical methods which are used to determine the amorphous phases and assess their performance via X-ray diffraction have been discussed with their benefits, limitations and applicability.

Abstract

In smart grid, massive high-precision real-time electricity consumption data recorded in smart meter seriously threatens user privacy safety. In this paper, we propose an algorithm named DPRB (Data Precision Reduction Based) which can discretize smart grid energy supply into limited levels to control smart meter readings being several standard values rather than high-precision time-varying data, thus achieving the purpose of user privacy protection. We also consider time-sharing price and solar energy supply to reduce the total electricity cost. What’s more, according to the different ways of selecting values of the power supply of smart grid, the DPRB algorithm is divided into the BCM-DPRB (Best-Costsaving Method DPRB) algorithm and the RM-DPRB (Random Method DPRB) algorithm.

Abstract

Conventional air conditioner is considered as one of the most prevalent cooling systems over the recent decades. However, it has strong draught sensation and indoor noise. In order to avoid such drawbacks and improve the thermal comfort, a novel radiant heat exchanger based on air-conditioning unit is proposed. A series of experiments are conducted to investigate the thermal comfort of the cooling system. The results indicate that the predicted mean vote values are between -0.7 and 0.7, and the predicted percentage of dissatisfied values are less than 15%, which are all within the ranges recommended by ISO 7730 standard. The vertical temperature difference from 0.1 m to 1.1 m is approximately 1.5 oC, which is much lower than that of conventional air systems. Compared with conventional air systems, the radiant heat exchanger cooling system can improve the thermal comfort.

Abstract

In order to resist the frequent natural disasters, distribution networks should have the ability of rapid restoring from post-disaster. Multi-microgrids (MMG) are playing an important role in the restoration of distribution networks. Firstly, the response model of load for restoration is built. The charging and discharging models of vehicle-to-grid (V2G) in microgrid are also developed. Secondly, a bi-level multi-microgrids coordinated optimization dispatch model is presented to improve the restoration of critical loads in distribution networks. At the upper level, multi-objectives with the maximization profit of microgrid and the maximization contribution rate for restoring critical loads (CRCL) of distribution networks are proposed. At the lower level, a dichotomy optimization algorithm of restoring price (RP) is proposed to minimize the purchase cost of restoration of critical loads in distribution networks. Finally, the proposed optimization dispatch method is validated by the case study on a distribution network with multimicrogrids. The simulation results indicate that the restoration is effectively improved through the proposed optimization dispatch method.

Abstract

This study analyzes emissions projections of CO2, air-pollutants and short-lived climate pollutants (SLCPs) in China and India due to various combinations of lowcarbon and air pollutants control measures, and evaluates the required additional investment costs of combinations of measures as well as the cobenefits in reducing air pollutants in response to low-carbon measuresfor achieving a 2 °C global temperature change limit above pre-industrial levels, so-called “2 °C target”. It was found that, even if combinations of lowcarbon and air pollution control measures are different, there are similar CO2 emission projections for achieving the 2 °C target. However, different combinations of these measures make major effects on diverse emission projections of air pollutants and BC. It is because major emission sources of air pollutants and BC are diverse in different technologies in different sectors. In addition, investment costs of end-of-pipe measures are cheaper than low carbon measures. As a result, depending on combinations of low-carbon and air pollution control measures, required additional investment costs are different. The lower carbon measures are taken, the more energy shifting occurs to renewables and the more additional investments are required. However, emission sources of air pollutants and BC are reduced and thus there will be less need for introducing end-of-pipe measures for air pollutants. It is important to highlight such cobenefits from the viewpoint of reducing both emission amounts of air pollutants and BC and investment costs.

Abstract

A reliable prediction of energy consumption is crucial for a reasonable building energy management. Considering the uncertain principles of annual electricity consumption with limited datasets, a modified grey interval prediction model abbreviated as BOGIM(1,1) is proposed in this paper. Firstly, the changing patterns of annual series were detected, in order to lower the uncertainty. Afterwards, the predicted intervals were obtained with modified BOGIM(1,1), in which various weakening and enhancing buffer operators were added simulate different future operation scenarios. Finally, the adaptability of this model is summarized based on recognized patterns and predicted accuracy. Specifically, 92 office buildings in Beijing of China were adopted to test the BOGIM(1,1) model. Results show that this proposed model outperforms the traditional GM(1,1) by improving the prediction accuracy for almost 90% of the buildings up to 18.45%, and it is more applicable for target-oriented energy policies.