An overview of hydrogen as a vehicle fuel

As hydrogen fuel cell vehicles move from manifestation to commercialization, the users expec t safe, convenient and customer-friendly fuelling. Hydrogen quality affects fuel cell stack performance and life time, as well as other factors such as valve operation. In this paper, previous researcher’s development on hydrogen as a possible major fuel of the future has been studied thoroughly .Hydrogen is one of the energy carriers which can replace fossil fuel and can be used as fuel in an internal combustion engines and as a fuel cell in vehicles. To use hydrogen as a fuel of internal combustion engine, engine design should be considered for avoiding abnormal combustion. As a result it can improve engine efficiency, power output and reduce NOx emissions. The emission of fuel cell is low as compared to conventional vehicles but as penalty, fuel cell vehicles need additional space and weight to install the battery and storage tank, thus increases it production cost. The production of hydrogen can be ‘carbon-free’ only if it is generated by employing genuinely carbon-free renewable energy sources. The acceptability of hydrogen technology depends on the knowledge and awareness of the hydrogen benefits towards environment and human life. Recent study shows that people still do not have the sufficient information of hydrogen

Exergy analysis of a hydrogen and water production process by a solar-driven transcritical CO2 power cycle with Stirling engine

This study attempts to go beyond the conventional framework of the integrated solar transcritical CO2 power cycle works, aimed at further utilization of available exergy as much as possible. This paper proposed a novel system for hydrogen and fresh water production in which a Stirling engine used instead of a condenser, for the places with abundant access to solar radiation and sea, and least to freshwater sources. This proposal leads to further utilization of streams’ exergy through the system instead of wasting to the environment, and further power production by the engine followed by the higher products. The electrolyzer employed beside Reverse Osmosis (RO) desalination system, and takes full advantages of highly concentrated brine stream of desalination, eliminating the wastewater rejection through proposed system leading to attaining a near-ZLD approach in fresh water and hydrogen production. This reduces the adverse impacts of desalination’s wastewater on the environment. A thermodynamic and exergy analysis is carried out to compare the superiority of this study and investigate the effect of some key parameters on the overall performance of the system as well. The results showed that replacing the condenser by a Stirling engine reduces the exergy destruction through heat transfer from CO2 to an LNG unit. Exergy destruction was reduced from 16.7% to 8.8% for the above configuration for an ideal Stirling engine that exploits it to produce extra power which its minimum is at least 9 kW and 15 kW higher than CO2 and LNG power productions. Moreover, Entering RO brine stream, wasting 2.58 kW exergy, to the electrolyzer leads to NaClO and H2 production besides removing brine stream. In a power plant, sodium hypochlorite is used for disinfection of cooling systems and hydrogen can be used as a source of energy in fuel cells. An examination of some thermodynamic factors showed that higher CO2 turbine inlet pressure has an optimum value in producing fresh water and hydrogen, while the higher CO2 turbine inlet temperature slightly reduces the productions rate. The more recovery ratio also causes a sharp reduction in hydrogen production, whereas it has an optimum amount of fresh water production at recovery ratio equals to 0.47

PUTTING CUSTOMER SERVICE AT RISK: WHY AND WHEN FAMILY OSTRACISM RELATES TO CUSTOMER-ORIENTED BEHAVIORS

This study examines why and when family ostracism can have an adverse effect on employees’ customer service behaviors. Drawing on self-determination theory (SDT), we theorize the existence of moderated multi-mediation relationships between family ostracism and employees’ customer service behaviors (i.e., customer-oriented organizational citizenship behaviors and customer-oriented voice behaviors) through harmonious passion for work and customer orientation, with social skills playing a moderating role. We used a time-lagged design to collect data from service employees in China. Our results show that controlling for workplace ostracism at Time 1, the relationship between family ostracism and employees’ customer service behaviors is negative and serially mediated by both harmonious passion for work and customer orientation. Furthermore, employees who are less socially skilled are more prone to the adverse effects of family ostracism. Last, female employees are more vulnerable to the effects of family ostracism on their customer service

Multi-Objective Optimization in a Finite Time Thermodynamic Method for Dish-Stirling by Branch and Bound Method and MOPSO Algorithm

There are various analyses for a solar system with the dish Stirling technology. One of those analyses is the finite time thermodynamic analysis. By the finite time thermodynamic analysis, the total power of system can be obtained by calculating the process time. In this study, the convection and radiation heat transfer losses from collector surface, the conduction heat transfer between hot and cold cylinders and cold side heat exchanger have been considered. During this investigation, the four objective functions have been optimized simultaneously. These objective functions are included of the power, efficiency, entropy and economic factors. In addition to the four-objective optimization, three-objective, two-objective and single-objective optimizations have been done on the dish-Stirling model. In this study, the algorithm of MOPSO with post-expression of preferences is used for multi-objective optimizations while the Branch and Bound algorithm with Pre-expression of preferences is used for single-objective and multi-objective optimizations. In case of multi-objective optimizations with post-expression of preferences, Pareto optimal front are obtained, afterward by implementing the Fuzzy, LINMAP and TOPSIS decision making algorithms, the single optimum results can be achieved. At the end, the comparison of the results shows the benefits of MOPSO in optimizing dish Stirling finite time thermodynamic equations

Virtual Sensor Based on a Deep Learning Approach for Estimating Efficiency in Chillers

P. 307-319Intensive use of heating, ventilation and air conditioning (HVAC) systems in buildings entails an analysis and monitoring of their e ciency. Cooling systems are key facilities in large buildings, and par- ticularly critical in hospitals, where chilled water production is needed as an auxiliary resource for a large number of devices. A chiller plant is often composed of several HVAC units running at the same time, be- ing impossible to assess the individual cooling production and e ciency, since a sensor is seldom installed due to the high cost. We propose a virtual sensor that provides an estimation of the cooling production, based on a deep learning architecture that features a 2D CNN (Convolu- tional Neural Network) to capture relevant features on two-way matrix arrangements of chiller data involving thermodynamic variables and the refrigeration circuits of the chiller unit. Our approach has been tested on an air-cooled chiller in the chiller plant at a hospital, and compared to other state-of-the-art methods using 10-fold cross-validation. Our re- sults report the lowest errors among the tested methods and include a comparison of the true and estimated cooling production and e ciency for a period of several daysS

Double diffusion natural convection in a square cavity filled with nanofluid

Double diffusive natural convection of nanofluid is commonly found in renewable energy engineering. However, nowadays our understanding on its fundamental characteristics is still limited. Especially, three crucial questions on its fundament have not been answered yet: (1) its performance not only in laminar regimes but also beyond laminar regimes, (2) the influence of the ratio of buoyancy forces on heat and mass transfer, (3) the correlation among the dimonsionless quantities which describe the features of this kind of convection. The present work tries to reveal the characteristics of double diffusive natural convection of nanofluid over a wide range, from laminar regimes to turbulent regimes, with the aid of numerical experiments. It is observed that the behavior of nanofluid in the laminar regimes is different from that in the turbulent regimes. Some conclusions presented in previous literature for laminar double diffusive of nanofluid may be invalid in its turbulent counterpart. The effect of the ratio of buoyancy forces on heat and mass transfer of nanofluid possesses some similarities with the pure base fluid as well as some obvious differences. Especially, a power-like correlation among the Nusselt number, Sherwood number, Rayleigh number, ratio of buoyancy forces and nanoparticle volume fraction has been extracted for the first time through our numerical experiments

Graphene nanoplatelets–cellulose nanocrystals in engine oil for automotive applications

The friction and wear of worn surfaces is a principal cause of energy dissipation in automobile engines. The current study investigates graphene nanoplatelets (GNPs), based on a carbon allotrope, that have good thermal, physical and chemical properties, and cellulose nanocrystals (CNCs) as a universal nano-sized ecological biopolymer. In view of this, the objective of the present work is to enhance the tribological behavior and lubricant properties using hybrid GNPs and CNCs blended with SAE 40 engine oil with various concentrations in the range 0.01–0.10%. The characterization was carried out by using different techniques such as X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The XRD patterns confirmed the platelet structure of GNPs, and FESEM showed that the sizes of small and agglomerated particles were 20–50 and 200 nm for GNPs and CNCs, respectively. Scanning electron microscopy morphological evaluation was conducted for all volumetric concentrations of single and hybrid nanolubricants. Morphological investigation indicated that there is homogeneous dispersion and there is a smoother surface after using graphene:CNC nanolubricants compared with that using just SAE 4

Understanding demand for, and feasibility of, centre-based child-care for poor urban households: a mixed methods study in Dhaka, Bangladesh

Background: Centre-based child-care has potential to provide multiple health and development benefits to children, families and societies. With rapid urbanisation, increasing numbers of low-income women work with reduced support from extended family, leaving a child-care vacuum in many low- and middle-income countries. We aimed to understand perceptions of, and demand for, centre-based child-care in Dhaka, Bangladesh among poor, urban households, and test the feasibility of delivering sustainable centre-based child-care. Methods: We used sequential mixed methods including a household survey (n = 222) and qualitative interviews with care-givers (n = 16), community leaders (n = 5) and policy-makers (n = 5). We co-produced and piloted a centre-based child-care model over ten-months, documenting implementation. A co-design focus group with mothers, parents’ meetings, and qualitative interviews with child-care centre users (n = 5), non-users (n = 3), ex-users (n = 3) and staff (2) were used to refine the model and identify implementation issues. Results: We found 24% (95% CI: 16,37%) of care-givers reported turning-down paid work due to lack of child-care and 84% (95% CI:74, 91%) reported wishing to use centre-based child-care and were willing to pay up to 283 Takka (~$3.30) per month. Adjusted odds of reported need for child-care among slum households were 3.8 times those of non-slum households (95% CI: 1.4, 10). Implementation highlighted that poor households needed free child-care with food provided, presenting feasibility challenges. Meta-inference across quantitative and qualitative findings identified the impact of the urban environment on child-care through long working hours, low social capital and fears for child safety. These influences interacted with religious and social norms resulting in caution in using centre-based child-care despite evident need. Conclusion: Sustainable provision of centre-based care that focuses on early childhood development requires subsidy and careful design sensitive to the working lives of poor families, particularly women and must respond to the dynamics of the urban environment and community values. We recommend increased research and policy focus on the evaluation and scale-up of quality centre-based child-care, emphasising early-childhood development, to support low-income working families in urban areas