Abstract

In this study, the part-load performance of a gas engine-driven heat pump (GHP) system for cooling application was studied. A novel energy-efficient air source GHP experimental setup was designed based on the use of scroll compressors with R410A. The waste-heat-recovery efficiency (ηh) under different engine speed Neng (1200-2400 r/min) was studied under the no-load operation of the engine. The experimental study on part-load characteristics of the GHP system was carried out under the cooling load rates (Lperc) of 25 %, 50 %, 75 %, and 100 %. The results show that the ηh of the GHP system is between 53.8% and 59.6% under different Neng. With the increase in Lperc, the values of Qc, Pgas, and Pcomp all increase gradually, whereas PER, PERall, and Pcomp initially exhibit an increasing trend, and subsequently, exhibit a decreasing trend. It shows that the GHP system has higher energy efficiency at middle part-load during cooling operation. The values of IPLVCOP and IPLVPER in the GHP system are 4.435 and 1.256, respectively, which indicates that the GHP system has an efficient integrated part-load performance.

Abstract

Integrated energy systems can benefit substantially from flexibility provision in their operations. This paper explores the operational cost optimisation of a UK public facility dedicated to health services by harnessing the flexibility gained from available gas and electricity grid inputs, a combined heat and power unit, and integration of thermal and electrical energy storage units into the local network. The optimisation algorithm assists in the sizing of the storage units under different cases of fuel price and energy storage efficiency. Optimal integration of energy storage results in operational cost savings of £7.6/day under normal operating conditions and of £64.7/day for an elevated gas price. The findings are based on real-time energy price and demand profiles and reveal that the local energy system benefits more from the thermal stores than from electrical energy storage.

Abstract

The weakly volatile crude oil in the carbonate reservoir is easily degassed when the pressure is reduced. In this paper, weakly volatile oil with similar dissolved gas-oil ratio to actual oil field was prepared, and three fracture occurrences carbonate cores were designed. The self-designed oil-gas-water three-phase metering device was used to accurately measure the flow. The research results showed that GOR presented three stages: rising stage, falling stage and steady rising stage. For the GOR of low-angle through fracture core, the peak value is the highest during water injection. In studies of different depletion degrees, an appropriate degree of degassing not only effectively utilizes the elastic energy of the gas, but also reduces the development cost of the oil field.

Abstract

and challenging. Heat pumps are promising technolo-gies with strong dependencies on heat source temper-atures. Using heat sources with higher temperatures lead to better efficiencies of heat pumps. One heat source that is available in regions worldwide where mining used to be a part of economic activities is water from coal mining. This article investigates the possibility of reusing the abandoned mining areas in the Ruhr area, Germany, in particular the possibility of using the heat from mine water to distribute it to heating net-works. The former mine operator needs to pump mine water to the surface for eternity. For the analysis of the mining infrastructure, all existing and relevant data of the shaft locations were analysed. In the process, 7,800 documented shafts were identified. The totality of shafts was reduced by exclusion criteria in the first analysis to 119 potentially usable sites in the Ruhr area. Based on this, a categorised evaluation of the remain-ing sites was carried out with regard to their technically developable utilisation potential. This evaluation is based on the conditions of the shaft locations, sup-plemented by the underground main flow paths and volume flows of the mine water. Results show, that 150,000 households can be supplied with heat from mine water. The findings are generally transferable to other areas with former coal mining activities, e.g. in the UK and other regions worldwide.

Abstract

This study developed a framework for commercializing window-integrated photovoltaic (PV) panels along with overcoming the limitations of existing window system. The developed framework determined the optimal window-integrated PV panel among window-integrated PV panels according to 3rd generation PV panel type and visible light transmittance (VLT) by considering three aspects: (i) occupant satisfaction; (ii) energy performance; and (iii) economic feasibility. The developed framework consisted of three steps. First, data on building and window-integrated PV panel were collected. Second, various window-integrated PV panels were evaluated in three aspects. Third, the optimal window-integrated PV panel was determined through multi-objective optimization.

Abstract

Hydrogen energy provides an approach to addressing the energy crisis and global climate change. However, additional energy consumption and carbon emission in the conventional storage process of H2 tackle the hydrogen economy’s prosperity. Metal-organic frameworks (MOFs), new type materials with exciting structures and properties, represent a blueprint for realizing large-scale applications of hydrogen energy by lowering energy consumption and cost of facilities. Traditional hydrogen storage MOFs have stepped to an advanced level, and the discovery inevitably slows down. Materials are fundamental to low-cost hydrogen storage, and the screening and design of H2 storage MOFs are crucial for the hydrogen economy. We aim to propose a novel paradigm of hydrogen storage MOFs material design that combines machine learning and first principles calculation, such as density functional theory (DFT). By constructing an active learning framework and using DFT calculation results as training data, a self-improving model that can screen existing material databases and guide experiments design is obtained. The prediction model’s performance is examined in conventional ways (root mean square error, coefficient of determination, etc.) and will be further tested in practical considerations (test the performance of MOFs guided by the model).

Abstract

We link the highly flexible Energy System Model Backbone with Life Cycle Assessments of energy system technologies to optimize various environmental impact indicators in addition to system costs. Additionally, we perform a multi-objective optimization of costs and environmental impacts and determine a pareto front to investigate interrelationships and trade-offs even further. We apply this to the power system of twelve central european countries with a special focus on the Rhenish Mining Area, a structural change region in western Germany, in the year 2040. This reveals a decrease in electricity generation in the region for all objective functions compared to 2020, as well as a strong preference for gas power for cost minimization and onshore wind power for minimization of environmental indicators.

Abstract

Renewable energy sources have gained increasing importance for mitigating the negative effects of climate change while meeting the globally rising demands for energy. In reality, however, regions where renewable energy sources can be readily tapped are often far away from industrial or urban centers of energy demand, necessitating long distance energy imports. Transmitting electricity over long distances is impractical and costly. Secondary energy carriers such as hydrogen produced through water electrolysis could be a sustainable means to convert renewably generated electricity, e.g., from wind or photovoltaic power plants, to chemical products that can be readily transported and stored. This work compares the environmental impacts of local hydrogen production to its remote production with the associated transport over various distances. We aim to evaluate, if and under which conditions the import of hydrogen is environmentally more favorable than local hydrogen production. It was found that hydrogen produced by water electrolysis powered by renewable energy sources is more climate-friendly than that generated locally by conventional steam methane reforming. Even so, to minimize the global warming impact related to hydrogen production, there is indeed an environmentally relevant trade-off: Balancing the best available local conditions for hydrogen production via renewable sources with the minimum transport distance to the consumers.

Abstract

With the increasing focus on black carbon emissions in the International Maritime Organization, It is increasingly important to study the influence of fuel sulfur content on marine diesel engine emission, especially on particulate matter emission, a 4.5 L Marine auxiliary engine was tested with different Fuel sulfur content FSC (0.26% , 0.05% and 0.005%), the effects of fuel sulfur content on the Brake Thermal Efficiency (BTE) were analyzed. And then the variations of conventional and unconventional gas emissions with FSC were measured, such as CO, CO2, CH4, and SO2. Then, based on the difference of the FSN and the PN of PM, the effect of PM morphology was discussed. The results show that with the increase of sulfur content, BTE decreases, CO and THC emissions increase, which are due to the more presence of fuel incomplete combustion products. With the increase of FSC, the fractal dimension(Df) of particle aggregates increases, the rotational diameter(Dg) of particle aggregates increases, more particles are tightly bound together in clusters. So that PN decreases, but FSN increases.

Abstract

SOFC/GT (Solid Oxide Fuel Cell-Gas Turbine) hybrid system is proposed as one of the advanced power systems of future ships due to its high efficiency, low emission and fuel flexibility. However, how to efficiently reform marine diesel into H2 is the key to maintaining the operation of SOFC/GT. The paper studies the influence of operating parameters such as steam to carbon ratio (S/C), temperature and pressure of ship SOFC/GT hybrid system on H2 production characteristics of marine diesel reforming through numerical simulation and experimental analysis. The results show that under the rated operating condition, the H2 mole fraction in reformate accounts for 50%, and the absolute error of the H2 mole fraction between the simulation result and the experimental result is 2.67%. Under the variable working conditions, in the range of 923~1123K, the H2 production increases with the increase of temperature and the carbon deposition decreases. When the temperature increases to 1123K, the mole fraction of H2 reaches a maximum of 56%, and the H2 yield reaches a maximum of 2.65. The increase of S/C promotes the increase of H2 yield and inhibits carbon deposition. Pressure has a negative effect on H2 production. The research results can provide basic technical support for the safe and efficient operation of the SOFC-GT hybrid power system on ships and the continuous supply of fuel.