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Abstract Limiting the increase of global temperature requires electrification of the railway transport, which is relatively a distinct mode of transport in terms of economy, business and socialization of a country. However, battery complemented railway transport systems such as fuel cell hybrid railway propulsion systems are constrained by the high cost of the battery, and suboptimal performance of the fuel cell under varying loads. Optimized selection of battery can reduce its costs associated with sizing, life and utilization. Similarly, managing the load distribution between the battery and fuel cell can reduce the load variations concern for fuel cell. In this study, model-based selective characterization of the battery and fuel cell is done to identify the optimal features and constraints. Following characterization, the load allocation to battery and fuel cell is determined with the targets of collaborative utilization of optimal features and mitigation of constraints. Subsequently, considering this load allocation and results of characterization, conditions are proposed for reliable sizing and optimized selection of battery. The significance of the proposed conditions in reliable sizing is explored. Based on these conditions, certain commercially developed batteries are evaluated for optimized selection of battery. The results signify this study as a foundation for research on the reliable sizing and optimized selection of battery in fuel cell hybrid railway propulsion systems.

Abstract An attempt was made to develop multiple regression models for office buildings in the five major climates in China – severe cold, cold, hot summer and cold winter, mild, and hot summer and warm winter. A total of 12 key building design variables were identified through parametric and sensitivity analysis, and considered as inputs in the regression models. The coefficient of determination R2 varies from 0.89 in Harbin to 0.97 in Kunming, indicating that 89–97% of the variations in annual building energy use can be explained by the changes in the 12 parameters. A pseudo-random number generator based on three simple multiplicative congruential generators was employed to generate random designs for evaluation of the regression models. The difference between regression-predicted and DOE-simulated annual building energy use are largely within 10%. It is envisaged that the regression models developed can be used to estimate the likely energy savings/penalty during the initial design stage when different building schemes and design concepts are being considered.

Abstract Interest in solar chimney power plant (SCPP) has seen resurgence due to the continuously increasing awareness on environmental concerns, particularly greenhouse gas emissions from fossil fuels, since the 21st century. Although remarkable advances in the understanding of SCPP have been achieved through extensive theoretical, experimental, and numerical studies with different focuses on various aspects of the SCPP technology, no industrial scale SCPP has been built. In response to these new scientific advances and challenges for commercialization, seven questions, including parameter influences, turbine design, flow and heat transfer characteristics, similarity analysis, and hybrid systems, are presented in this work. In addition, answers and current understanding are included to provide succinct links to latest knowledge and identify areas that require further research.

Energy is essential for industrial production. Because of the past abundance of low-cost energy, historically, the rate of social progress among industrial societies has not been limited by energy availability. Energy cost has not been significant when compared with no energy use. Mechanisation of agriculture, increased use of electrical appliances in the domestic sector and rapid industrialisation to meet the demand of exponentially growing population have resulted in an energy crisis. The raised fossil fuel prices and the environmental factors playing the dominant role in implementation of large scale projects, such as hydro, thermal and nuclear, have aggravated the problem further. In this context, an integrated energy plan for a country seems essential for ecologically sound development of a region. An integrated plan includes strategies to: • improve the efficiencies of end use devices and/or conversion equipment in all sectors; • optimise energy sources (end use matching); • maximise the use of renewable resources; • balance the exploitation of biomass energy resources; and • discourage the use of depletable resources. Conservation through improvement of the efficiencies of end use devices is one of the most effective ways to provide immediate relief for the energy problem. This helps to maintain economic growth and social progress of a region. Environmental problems, resource depletion and growing demand of energy in the state/region make it increasingly imperative that we use energy as efficiently as possible, and planners should take note of this untapped resource. The potential for improved energy efficiency is great, and a substantial part of that potential could be realised in the course of events. The industrial sector constitutes a major consumer of commercial energy. Improvement of energy efficiency in the industrial sector would result in a slower rate of energy growth. A secure energy supply is the major concern of most industrialists. It is, thus, necessary to examine industrial energy use and the economy. The analyses of consumption patterns and the assessment of feasible energy conservation possibilities show that the potential for energy conservation in the industrial sector and in all sectors is substantial. The barriers identified to tap this potential are a lack of information on specific measures and options for achieving energy conservation, lack of capital for schemes involving technology upgrading and efficiency improvements, pricing policies which deviate from rational tariffs and the inadequacy of institutional arrangements for promoting energy conservation in different sectors of the economy. In this regard, research should be sponsored to develop system designs, cost and pricing policies, problems related to system interconnection with public utilities and an assessment of potential energy savings, and research into methods of matching energy resources to work requirements, rather than vice versa, for improved efficiency. It is essential for the planning machinery to foster the integrated approach in energy planning of a region. This paper discusses an attempt made by us to illustrate the industrial energy scene in Karnataka and reveals the possibilities of energy conservation. Analysis of the energy consumption data of Karnataka and India shows that the per capita consumption of energy is low (compared with 56 countries in the world), while for the industrial sector, energy per state domestic product (SDP comparable to GDP) is at least 10–20 times higher than that of industrialised countries. This implies inefficiency in energy utilisation. Detailed investigation of the industrial sector through analysis of the Specific Energy Consumption (SEC)—industry wise and yearly for a seven-year period—reveals that about 27.72% of energy could be saved in the industrial sector. This, when quantified, accounts for savings of 1541 million kWh per year in Karnataka, which is equivalent to the power output of 300 MW (Mega Watts) electric power generating station (hydro/thermal).

Abstract In the present work, a novel hybrid solar-based smart building energy system is introduced and studied. The system comprises innovative photovoltaic-thermal-cooling (PVTC) panels integrated with hot and cold storages with two-way interaction with electricity, heat, and cooling networks (if any). The proposed system is compared with PV-based systems integrated with battery and heat pump for a case study complex building in Aarhus, Denmark. The comparison is conducted by evaluating the performance and economic indicators and investigating the effect of significant parameters on each scenario via a parametric study. Furthermore, the optimal operating conditions and sizing of the proposed system are determined using the genetic algorithm method considering initial cost and traded energy with local energy networks as the objective functions. The comparison results show that the proposed solution is the most cost-effective scenario with the lowest initial cost of about 457,000 $ and a payback period of 6.6 years. This is mainly due to the simultaneous interaction with electricity/heat/cooling networks as well as the elimination of the battery and the heat pump, which are offered by the proposed scenario. It is shown that, in comparison to PV panels, the PVTC can produce 328.7 MWh and 125.6 MWh extra heat and cooling annually. The scatter distribution of significant parameters shows that the panel area and heat storage capacity are not sensitive parameters, and keeping the cold storage capacity at the lower bound is a techno-economically better option.

Energy consumed in building and construction accounts for 40% of the total end-use energy. To achieve the energy reduction in this area, conventional construction approaches need to be reshaped. To overcome existing challenges, this study explores the use of 3D cementitious material printing (3DCMP) and investigates the printability of these cementitious materials incorporated with the phase change material (PCM). To realize the newly developed composite cementitious materials for real-world applications, we examinate the benefits of utilizing them for building's energy consumption reduction. From our study, we demonstrate, for the first time, the successful fabrication of the PCM composite wall by 3DCMP method. The enthalpy porosity method is then proposed to study the time-dependent thermal performance of the composite wall by modelling the encapsulated PCM and cementitious material as porous and medium, respectively. Our results show the proposed model is reliable in predicting the PCM composite wall thermal performance and demonstrate the composite wall has the potential of smoothing and reducing energy consumption by the building. From our investigation, it is determined that the PCM melting temperature should be chosen based on heating time and heat power density. Additionally, the total cost of precasting a wall by conventional methods with a dimension of 4 m × 0.12 m × 2.8 m (L × W × H) is 28.4% higher than the printing counterpart. Furthermore, the performance enhancements resulted in approximately 30% savings in building energy consumption during the day using plain walls infused with 3% PCM. This study not only demonstrates the potential of fabricating enhanced building materials through the utilization of additive manufacturing technique, but it also provides the guidelines to design PCM composite walls under various operating conditions. ; National Research Foundation (NRF) ; This research is supported by the National Research Foundation, Singapore, Prime Minister’s Office, Singapore under its ...

Abstract The optimal turbine pressure drop ratio fopt for a solar chimney power plant (SCPP) is investigated using an analytical approach and 3D numerical simulations. Results indicate that the solar radiation and ambient temperature have obvious influences to the optimal turbine pressure drop ratio fopt and an improved performance of the SCPP system leads to a high fopt. The performance comparison between the cases with different collector shapes, a circular collector and a square collector with the same area, is conducted for the first time. It is found that the m-th power law assumption can also be applied to the SCPP system with a square collector; the values of fopt for the cases with a square collector are close to those for the cases with a circular collector. A fitting equation with variables of solar radiation and ambient temperature is obtained using the simulation results of the Spanish prototype; the results reveal that the fopt of the Spanish prototype ranges from 0.90 to 0.94 under normal climate conditions. This paper provides an approach to the preliminary estimation of plant performance, and reference data for an optimal pressure drop through solar chimney turbines.

Abstract A type of smart window using thermochromic glazing (TCG) is a promising technology for green buildings owing to the self-regulating feature and low-maintenance need. Its most important feature, thermo-optical properties that regulate the blockage of solar heat, is directly linked to the variation of surface temperatures. However, challenges from the inhomogeneity of thermo-optical properties, the coupled solar radiation and natural convection, and varying outdoor conditions all seriously hinder the understanding of its mechanism. In this paper, a validated Computational Fluid Dynamics (CFD) model achieves the simulation of inhomogeneous tinting of TCG by defining the thermo-optical properties of each finite volume according to the surface temperature. Solar radiation and natural convection at outdoor, indoor and the cavity are solved to reflect glazing temperature more accurately. The case studies compared six different switching temperatures in the range of 20 ∼ 42.5 °C with a transition gradient of 10 °C. Averaged meteorological data for both summer and winter, sunny days and cloudy days are selected to present realistic climate impacts. The result reveals the overall saving in transmitted solar radiation in summer and heating penalties in winter. It suggests the best switching temperatures for each climate condition. With the seasonal operation, the highest saving in solar heat gain is 20.9% when adopting a switching temperature of 25–35 °C, while the lowest saving can be negative, meaning TCG is not suitable for those climate zones. The proposed evaluation criteria help to quantify the applicability of TCG with the input of the summer/winter day ratio and sunny/cloudy ratio. The best region to apply TCG is where summer days are longer and winter solar radiation is significantly lower. The in-depth understanding of this temperature-sensitive process benefits the optimization of TCG in buildings, especially for its seasonal operation needs.

Abstract Photovoltaic (PV) windows are promising to reduce building net energy usage by power generation, cooling and lighting loads reduction. However, their shading effect usually leads to the rise of heating loads. A novel reversible PV window was proposed, which shared the same performance of a common one in summer but improved the solar energy utilization efficiency in winter by rotating the PV glazing into the room and reducing the heat lost to the environment. A numerical model of the proposed PV window was developed and validated with experimental data. By using the model, the thermal and electrical performance of the proposed PV window was investigated in the heating periods of Beijing and the influence of key factors on it was revealed. In comparison with a common double-glazed PV window, though the proposed one generated less electric power, its benefits from heating loads reduction outperformed the power reduction. In winter, its net electricity saving increased with the decrease of PV transparency and with the increase of glazing transmittance, and it could be 1.42–10.78, 15.67–34.57 and 18.81–39.78 kWh·m−2 lower than the reference one in naturally ventilated, non-ventilated and auto modes, respectively.