Deciding the location of bio refinery is an important task for management in biofuel supply and demand. This work presents a single-period deterministic model for the optimal location of butanol refinery. The developed model considers a whole system approach for butyric acid supply, butanol refinery and delivery systems. The proposed model determines where and how many refineries to be constructed and components (butyric acid and butanol) to be transported for minimizing the expected total network cost and satisfying regional demand of biofuel. The real scenario of the biofuel demand by region in South Korea is applied to validate the mathematical model. The optimization results will help to determine investment strategies for butanol production.
Microalgae biomass is composed of various bio‐ compounds which can be converted to biofuels. One type of solid fuel which can be derived from microalgae is biochar through torrefaction. However, the production of torrefied microalgae biochar may include environmental impact as it consumes raw materials and energy. A life cycle assessment of the production of torrefied microalgae biochar is proposed in the study using the torrefaction severity index. The results show the electricity requirement of the torrefaction largely contributes to the environmental impact and energy consumption. While the resulting global warming potential of the production of torrefied microalgae biochar using the torrefaction severity index yielded a non‐linear relation.
Over the past two centuries, the research on working fluids drove the tremendous progress of organic Rankine cycle to convert medium- and low-temperature heat into power efficiently. With the increasingly stringent requirements on working fluids, the search for alternative working fluids is a never-ending task. In the present work, a comprehensive review of working fluids selection of ORC is presented to summary the current research results, find out the issues and guide the future developments. The research of working fluid selection is divided into three stages according to research method firstly. Then, the research progress of each stages is summarized. In addition, the research challenges and recommendations for further research of working fluids selection and even for novel thermodynamic cycle are highlighted as well. The results show that for traditional ORC, the optimal working fluid could be selected almost by key parameters such as critical temperature, acentric factor and Jacob number, etc. More importantly, the development direction of novel thermodynamic cycle is presented.
Large scale utilization of solar energy has become an inevitable trend of an energy-efficient and environment-friendly society. A two-stage robust allocation model of solar energy equipments in district integrated energy systems is proposed in this paper with the uncertainty of solar irradiance and operating constraints of energy networks. To improve the solvability, the above non-convex non-linear model is converted to a 0-1 mixed integer second-order cone problem. The validity of the model is verified by typical cases.
Driven by climate change concerns, our energy system has been under steady change. Renewable energy sources are increasingly used to decarbonize our energy system, making it also more decentralized. At the same time, information and communications technologies (ICT) are enabling smart services for consumers, offering financial benefits through demand side management (DSM) programs. This study investigates various DSM solutions for a detached house in Northern Finnish conditions in 2050. A thermal model is used to model the thermal behavior of the building and test out DSM programs in direct electric space heating and underfloor heating alternatives. The 2050 scenarios are created from climate change projections, existing data on electricity generation and from projections on the future energy system and cost of electricity. The results indicate that load shifting with photovoltaic (PV) generation is a potential way of reducing costs and CO2 emissions both today and in 2050, but it lacks economic feasibility due to long payback times of the investments. Cost optimized direct electric space heating and underfloor heating are both able to provide economic and environmental benefits when compared to manually controlled heating. The scenarios presented in the paper suggest that 95-96% emission reduction can be achieved; however, the electricity cost of households is expected to increase by 174-253%. At the same time electricity consumption from the grid is expected to reduce by 3- 10% in all the scenarios.
Thermal management of large-format Li-ion cells is crucial due to their spatial- and temperature-dependent electrochemical reaction kinetics and heat generation. However, existing battery modeling mostly employs a pseudo-2D model which is not able to capture the local current density and temperature across the entire cell geometry. Therefore, in this paper, we propose a simplified 3D electrochemical/thermal model to investigate the temperature and voltage responses of a Li-ion pouch cell. Concurrently, a lock-in thermography experiment is conducted. The model can achieve good accuracy in predicting the surface temperature and cell voltage of the battery during cycling. A scaling analysis is subsequently carried out to determine the dimensionless numbers that affect the battery performance. The proposed approach helps to facilitate a fundamental understanding of the dominant mechanisms related to voltage polarization, heat generation and temperature non-uniformity.
The prospect of using biomass alone is broad, but there are a number of problems that make it difficult to achieve real profitability. In this paper, the thermal effects and reaction kinetics of cellulose and low-rank coal mixing at different mixing rates (25 wt%, 50 wt.% and 75 wt.%) and different heating rates (10 oC•min-1 , 20 oC•min-1 , 40 oC•min-1 ) were studied via thermogravimetric analyzer(TGA). The addition of low-rank coal can promote the formation of volatile substances in the copyrolysis process, and the degree of synergy is closely related to the heating rate and blending ratio. The kinetic results show that the average activation is 244.44 kJ•mol1 and 164.41 kJ•mol-1 when the low-rank coal blending ratio is 25% and 50%.
This study assessed the thermo-economic performance of membrane distillation (MD) for concentrating nutrients and recover process water from digestate at a thermophilic biogas plant. The input data were derived from mapping the Uppsala Vatten och Avfall biogas system, present knowledge on anaerobic digestion process management and technologies for biogas system operating conditions in Sweden. The study evaluated the potential for recovering waste heat from the digestate effluent and boiler flue gas for use in the MD system. The thermal energy requirement, size, and separation efficiency of the MD unit were based on a previous laboratory study. The study assessed the overall energy efficiency and costs estimation of a full-scale codigestion plant with thermally integrated MD. Presented results shows that the proposed model of integrated MD system has the best thermal performance. The recovered waste heat contributed total thermal energy demand of MD and additionally it could save 19% boiler energy by heating incoming slurry. The results showed that the MD product water permeate was 3.5 L/(m2 h) at 65°C digestate inlet temperature. Specific heat demand for MD was 100 kWh/m3 with internal heat recovery. Cost estimation showed that the unit cost of MD permeate water was 3.6 €/m3 at a digestate feed temperature of 65°C. The economic assessment indicated that thermal integration of a biogas plant with MD could be economically feasible. However, long-term continuous studies are needed to determine impact of fouling and membrane lifetime.
In recent years, architectural design with dynamic facade has been more widely introduced as a solution for building environmental issues. From the morphological point of view, this paper attempts to explore the performance otherness of different dynamic typologies during the optimisation of the design process. Take high-rise office building in the tropical region as an example, The two common typologies of rotation and folding are compared and discussed by parameter simulation method with 36 cases in terms of scale, motion and transmittance to find the optimal trade-off between minimising energy demand for cooling and lighting and maximising daylight comfort.
The results of the study show that the energy demand for cooling and lighting can be reduced by 19%- 24% through dynamic façade while folding typology has better performance in energy conservation in all the three orientations. For daylighting, the average daylight comfort area has an increase of 5%-14%, while the value of rotation typology is higher than folding typology. Furthermore, Motion has an influence on the daylight and energy performance except for energy demand of rotation typology. Differently, Transmittance is related to both performances except daylight of rotation typology. This study provides a performance-based approach to dynamic facade selection. A designer could make the decision not only from aesthetic considerations but also combine them to get higher performance.
This paper describes the study and research taken under Project oBEMS (Office Building Energy Management System). This is an intelligent hardware and software overlay for office building automation systems based on the advance methods for measuring thermal room conditions. This method allows for managing thermal comfort in certain space by controlling installed Heating, Ventilation and Air Condition system (HVAC) in real time with the use of multisensory map of comfort.