Abstract

To achieve better heat management in proton exchange membrane fuel cell (PEMFC) systems, a novel wavy-louvered fin-tube (WL-FT) heat exchanger is proposed. Three-dimensional numerical simulations based on OpenFOAM are utilized to investigate the thermal hydraulic performances of proposed structure, including heat transfer coefficient (HTC), pressure drop, heat flux and JF ratio. Effects of different wave length are studied. The results show that WL-FT heat exchanger with wave length 0.4 mm has the best performances, which achieves 8.1% higher in HTC and 10.8% lower in volume than conventional flat louver type.

Abstract

This paper investigates the coordinated pricing of urban electrified transportation networks enabled by the dynamic wireless charging technology of electric vehicles (EVs) in the future. The in-motion charging demand of EVs will create stronger interdependency between the operation of power distribution networks (PDN) and traffic networks (TN). The PDN locational marginal pricing and TN congestion pricing will affect the route choices of multi-class vehicles (i.e. vehicles charging or not charging). The aggregated traffic flow and charging load of vehicles will in return affect the operations and pricing of the PDN and TN. To investigate the benefit of coordinated pricing, the Stackelberg game is employed to model the above interaction between the utilities and strategies of PDN, TN, and vehicles under coordinated and uncoordinated pricing scenarios respectively. Case studies demonstrate the benefits of the coordinated pricing of the coupled networks.

Abstract

Data centers are energy-intensive buildings. Energy efficiency is an important indicator for data center energy consumption. The energy consumption of the data center needs to be measured under full load conditions. However, the data center cannot achieve full load generally. Therefore, it is necessary to open the dummy load equipment. The measurement takes long enough to get the energy efficiency value, which wastes a lot of energy. This paper introduces a new energy efficiency method of measurement and calculation. First, some temperature points are selected to measure the corresponding energy efficiency values. Then the energy efficiency-temperature model is obtained. Based on the imported annual meteorological data where the data center is located, the energy efficiency is finally calculated. Compared with the traditional method, this method takes less time and consumes less energy.

Abstract

An ex-situ visualization experimental system was established to study the growth and deformation process of a single droplet in a rectangular channel for the proton exchange membrane fuel cell (PEMFC). The droplet morphology was observed and recorded by a CCD camera. Three different methods for automatically obtaining droplet size and contact angle information were developed. The influence of air flow velocities on droplet dynamic process was analyzed.

Abstract

Although hydrogen fuel cell electric vehicles (HFCEVs) are more environment-friendly compared to the conventional vehicles, their energy consumption, emissions, and the economic impacts involved remain unclear from a life cycle perspective. Therefore, these aspects of HFCEVs were investigated herein using the GREET model under operating conditions for China. The results showed that HFCEVs can reduce the life cycle cost by 13.2%, energy consumption by 9.7%, and greenhouse gas emissions by 13.1% in comparison with gasoline internal combustion engine vehicles (GICEVs). However, the life cycle results showed that HFCEVs can increase the acidification potential by 111.7%, aerosol pollution by 273.9%, and human toxicity potential by 87.7%. Therefore, compared with GICEVs, the impacts of energy consumption and environmental emissions of HFCEVs are transferred from the use phase to the production phase of the fuel, and the purchase cost of HFCEVs is shifted from end users to the government.

Abstract

This paper presents the numerical results of soot evolution in a constant volume chamber under different exhaust gas recirculation (EGR) levels at an ambient temperature of 1100 K by employing a two-equation soot model. The contribution and significance of each soot process on the net soot mass production are investigated. The numerical setup is able to capture the experimentally observed monotonic trend of the soot mass, in which soot mass increases with decreasing oxygen (O2) level. The simulation results demonstrate that soot oxidation rates, particularly by hydroxyl radicals (OH), are the more dominating factors to the monotonic trend as compared to the inception and surface growth rates under different EGR.

Abstract

Nepal —a least developed country from South Asia— is targeting towards graduating to become a developing country by 2021. In Nepal, approximately 80% of the population lives in rural areas. The energy demand in rural households is dominated (~97%) by the use of emission-intensive cooking fuels such as firewood, kerosene, and cow dung, which is responsible for the significantly high (~25 MtCO2e in 2010) GHG emissions in rural households in Nepal. Therefore, the rural household sector in Nepal must transition to a sustainable form of cooking fuel to reduce its GHG emissions in the future. The objective of the study was to develop an energy-emissions model to estimate and forecast the effect of cooking fuel on energy demand and GHG emissions in the rural household sector in Nepal up to 2050. We showed that Nepal’s energy demand would be ~95 TWh by 2050 (1.3 times) than that of 2010 under Business-as-usual scenario. Furthermore, Nepal’s rural household sector may reduce 92% of GHG emissions and 84% total energy demand by 2050 as compared to 2010 by transitioning to electricity and LPG based cooking fuel.

Abstract

The distributed energy system is considered to be introduced in urban area, which proposes a new effective approach to improve the efficiency of energy system and the sustainability of urban. The present study proposes an integrated approach for optimal design of distributed energy system considering the optimization of supply side and demand side simultaneously. On the demand side, a scenario tree is established to quantify the energy saving technology including envelop upgrades of window, wall, roof. On the supply side, another scenario tree is developed to describe the variation of solar radiation, typical days, and typical seasons. Moreover, a MILP model is built to optimize the economic performance taking carbon tax into account. The results indicate that the combination of optimal selection of energy saving technology and optimal design of energy conversion technology enables the DES model to improve the economic performance, especially considering the carbon tax. Moreover, the optimal system configuration and dispatch strategy become more reasonable and flexible by introducing the demand side technology into DES planning model.

Abstract

The application of large-scale renewable energy projects, especially solar thermal, in the Middle East region and the Gulf Cooperation Countries, leveling with the region’s high potential, is facing many challenges, concerning the feasibility of a huge investment. One way to motivate policy makers is to use the excessive energy to produce Liquid Hydrogen for export to needed countries, making the investment profitable and helping reducing CO2 emissions levels worldwide. In this study the surplus electricity from, from different scenarios of Concentrated Solar Plants application, is used for Hydrogen production using three different technologies (Alkaline, PEM and SOEC) for technical comparison. Another two scenarios are considered, with different locations for the Hydrogen production sites, between CSP sites and ports, using Geographical Information System GIS, to assess the pathways for Hydrogen production.

Abstract

State of health (SOH) estimation is insightful for the lithium-ion battery (LIB) health management. This paper proposes a new set of health indicators (HIs) based on early-stage constant-voltage (CV) charging, which are easily available in practical vehicle applications. Particularly, a thorough analysis is performed over different CV-based HIs to obtain the informative ones with strong correlation against the SOH. A gaussian process regression (GPR) model is further employed to fusion the extracted HIs and to estimate the battery SOH. The proposed method is validated based on cycling experiments performed on the LiNiCoAlO2 cells. Results suggest that the proposed method promises multifold benefits, including the high estimation accuracy, low requirement on the charging integrity, and the high robustness to cell inconsistency.