bluuebunny/crossref_metadata_2025 huggingface dataset:
Irregular changes in Hα emission line of V423 Aur observed by LAMOST Medium-Resolution Spectrographs
Authors: Wu Chao-Jian , Wu Hong , Hsia Chih-Hao , Zhang Wei , Ren Juan-Juan , Li Guang-Wei , Chen Jian-Jun , Yang Fan , Shi Jian-Rong , Hou Yong-Hui , Liu Ji-Feng
Published: April 2020

We obtained seven spectra of the Be star V423 Aur on 2017 Dec. 5 using the LAMOST Medium-Resolution Spectrograph with exposures from 600 to 1200 seconds. These spectra show the irregular Hαemission line profile variations (LPVs). In the seven spectra, from the 4th to 7th, the left part of Hαprofile even shows excess. However, no variation can be seen from the follow-up observation of photometry by 1.26-m telescope and High-Resolution spectra by 2.16-m telescope. According to the High-Resolution spectra, we conclude that it is a B7V type star withE(B−V) = 0.709 ± 0.036 and itsvsini is ∼ 221.8 km s−1. The short-term HαLPVs could be explained as a result of the transient ejection of matter from rotating disk or shell around V423 Aur.
Spectral properties of the surface reflectance of the northern polar region of Mercury
Authors: Ngoc Nguyen Bich , Bott Nicolas , Diep Pham Ngoc
Published: April 2020

We analyze MESSENGER reflectance measurements covering the northern polar region of Mercury, the least studied region of the northern mercurian hemisphere. We use observations from the Mercury Dual Imaging System Wide-Angle Camera (MDIS/WAC) and the Mercury Atmospheric and Surface Composition Spectrometer (MASCS/VIRS) to study the spectral dependence of the surface reflectance. The results obtained from the observations made by both instruments are remarkably consistent. We find that a second degree polynomial description of the measured reflectance spectra gives very good fits to the data and that the information that they carry can best be characterized by two parameters, the mean reflectance and the mean relative spectral slope, averaged over the explored range of wavelengths. The properties of the four main types of terrains known to form Mercury’s regolith in the northern region, smooth plains (SPs), heavily cratered terrain (HCT), fresh ejecta/materials and red pitted ground (RPG), are examined in terms of these two parameters. The results are compared, and found consistent with those obtained by earlier studies in spite of difficulties met in obtaining accurate reflectance measurements under the large incidence angle condition characteristic of polar regions. These results will help with the preparation of the BepiColombo mission and with supporting its observational strategy.
Searching for exoplanets by HEPS II. detecting earth-like planets in habitable zone around planet hosts within 30 pc
Authors: Yu Zhou-Yi , Liu Hui-Gen , Zhou Ji-Lin , Liang En-Si , Yang Ming , Zhang Hui , Liu Jia-Cheng
Published: April 2020

HEPS (Habitable ExoPlanet Survey) is a planning astrometry satellite that aims to find Earth-like planets in the solar neighbourhood. In this paper, we selected 140 planet harboring stars within 30 pc of the solar system to be potential targets for HEPS. We calculate the detection probability of the planet in habitable zone (HZ) for each system using the simulated data of astrometry measurements. For those host stars without planets in HZ, we inject an additional planet of 10 M
⊕ in their HZs and check the stability of the systems. Considering five observation modes of different sampling cadence and total observation time, we obtain a table containing the total detection probability of the planets in HZs for all of the 140 selected systems. This paper provides a potential ranked list of target stars for HEPS, or other astrometric mission to detect Earth-like planets in the future. We also calculate an empirical fitted expression of the detection probability as a function of both sampling cadence and total observation time. We conclude a quantitative method to estimate the detection probability for certain planet hosts and observation modes via the empirical expression. We show the minimum requirements of both sampling cadence and observation time for Proxima Centauri, HD 189733 and HD 102365, if the detection probability of habitable-zone planets of these three systems needs to be 90%.
A study on the dynamic spectral indices for SEP events on 2000 July 14 and 2005 January 20
Authors: Zhao Ming-Xian , Le Gui-Ming
Published: April 2020

We have studied the dynamic proton spectra for the two solar energetic particle (SEP) events on 2000 July 14 (hereafter GLE59) and 2005 January 20 (hereafter GLE69). The source locations of GLE59 and GLE69 are N22W07 and N12W58 respectively. Proton fluxes >30 MeV have been used to compute the dynamic spectral indices of the two SEP events. Our results show that spectral indices of the two SEP events increased more swiftly at early times, suggesting that the proton fluxes >30 MeV might be accelerated particularly by the concurrent flares at early times for the two SEP events. For the GLE69 with source location at N12W58, both flare site and shock nose are well connected with the Earth at the earliest time. However, only the particles accelerated by the shock driven by eastern flank of the CME can propagate along the interplanetary magnetic field line to the Earth after the flare. For the GLE59 with source location at N22W07, only the particles accelerated by the shock driven by western flank of the associated CME can reach the Earth after the flare. Our results also show that there was slightly more than one hour during which the proton spectra for GLE69 are softer than that for GLE59 after the flares, suggesting that the shock driven by eastern flank of the CME associated with GLE69 is weaker than the shock driven by the western flank of the CME associated with GLE59. The results support that quasi-perpendicular shock has stronger potential in accelerating particles than the quasi-parallel shock. These results also suggest that only a small part of the shock driven by western flank of the CME associated with the GLE59 is quasi-perpendicular.
Dynamics of scrape-off layer filaments in detached conditions
Authors: Schwörer D. , Walkden N.R. , Dudson B.D. , Militello F. , Leggate H. , Turner M.M.
Published: April 2020

The here presented work studies the dynamics of filaments using 3D fluid simulations in the presence of detached background profiles. It was found that evolving the neutrals on the time-scale of the filament did not have a significant impact on the dynamics of the filament. In general a decreasing filament velocity with increasing plasma background density has been observed, with the exception of detachment onset, where a temporarily increase in radial velocity occurs. The decreasing trend with temporary increase was found for filaments around the critical size and larger, while smaller filaments where less affected by detachment. With detachment the critical filament size increased, as larger filaments were faster in detached conditions. This breaks the trend of attached conditions, where the critical size decreases with increasing density.
Energy infrastructure, NIMBYism, and public opinion: a systematic literature review of three decades of empirical survey literature
Authors: Carley Sanya , Konisky David M , Atiq Zoya , Land Nick
Published: April 2020

Public support is a key determinant of whether any energy project is developed in democratic countries. In recent decades, scholars have extensively examined levels of support and opposition to energy infrastructure, often with a focus on so-called Not-in-My-Backyard (NIMBY) sentiments. As the need for energy infrastructure grows, so does the need to extract insights and lessons from this literature. In this systematic literature review, we evaluate decades of research to identify important trends in topical focus, research findings, and research design. We find a disproportionate focus on wind energy, followed by solar, fossil fuels, and transmission, with most studies conducted in the United States or United Kingdom, and that individuals are more often supportive of energy projects than they are opposed. Scholars have examined the role of many factors in understanding attitudes toward energy infrastructure, and often find knowledge, trust, and positive perceptions about the benefits of projects to be positively correlated with support for projects, although with variation across energy types. NIMBY attitudes differ widely in approach and are often plagued by problematic research designs that limit inferences and the generalizability of findings. We provide a detailed discussion of these limitations and suggest areas in which the literature can expand.
The effect of gasoline-waste plastics oil blends on SI engine performance at high-speed rotation
Authors: Khairil  , Jihad Muhammad , Indra Riayatsyah Teuku Meurah , Bahri Samsul , Sofyan Sarwo Edhy , Jalaluddin
Published: April 2020

As well known that waste plastic could be considered a very serious environmental issue because of their disposal problems may affect human life. One of the solutions to solve the plastic waste problem is to convert the plastic waste become plastic oil. This research was aimed to study the effect of gasoline-waste plastics oil (WPO) blends on (SI) engine performance at high-speed rotation. In this experiment, the engine of Honda GP 160 H-SD was selected which has specification a single-cylinder spark ignition, power is 5.5 HP and output net 3600 rpm. The composition of gasoline-waste plastic oil blends was variated of about WPO-10, WPO-20 and WPO-30. WPO-10 means that the waste plastic oil was added in gasoline oil of about 10 % vol. The SI engine performance was elucidated such as engine power, specific fuel consumption and thermal efficiency. The experimental results show that increasing speed rotation from 1500 to 3000 rpm greatly increases engine output power and specific fuel consumption. Consequently, the thermal efficiency reduced by 21.1%. It is also found, the increasing of blending ratio to WPO-30 has dropped the SI engine power approximately by 10.3 %. As results the specific fuel consumption reduced by 17.4 % while thermal efficiency can be increased by 15.5 %.
Test of a modified small-scale biochar kiln
Authors: Petchaihan Lalita , Panyoyai Numpon , Khamdaeng Tipapon , Wongsiriamnuay Thanasit
Published: April 2020

The conventional kilns were used for biochar production, but it took more than 7-9 hours for processing, and its process temperature was not uniform because some of the material could be converted into biochar and used lots of heat source input resulting in low production efficiency. Then the objective of this research was to improve the biochar production by using modified biochar kiln by reducing the temperature distribution. A 50-liter kiln with a modified core was needed in this research. This core was heating source for the pyrolysis process. The heat source came from the combustion of biomass. The core pipe was core puncture diameter for releasing product gas between a process, and it was core puncture diameter in 3 sizes (i.e., 3.18 mm, 4.76 mm and 6.35 mm). Seven kilograms of corncob rice husk and longan peel were loaded in the biochar kiln using three kilograms of fuel. The physical and chemical properties of biochar were analyzed such as water content, pH, electrical conductivity (EC) using scanning electron microscope (SEM), and Energy-dispersive X-ray spectroscopy (EDX). The element and mineral compositions were also analyzed, including C, N, O, K, and P. It was found that most of the materials were converted into biochar at uniform temperature with the modified core. The temperature inside a kiln with the heat insulation the modified core was around 400-600°C better than the common core (100-700°C) and it took only 3 hours for the process. In terms of products obtained from pyrolysis condition, the average temperature positions inside the kiln were found to be 430 ± 583 °C, 271 ± 512 °C, and 189 ± 503 °C and consisted of biochar yield were found to be 45.7, 34. 3 and 31.4 wt.% for rice husk, corncob, and longan peel, respectively. Gas yields were found to be 68.6, 68.6, and 48.6 wt.% for longan peel, corncob, and rice husk, respectively Ash yields were found to be 10.0, 5.7, and 5.7 wt.%, for longan peel, corncob, and rice husk, respectively. The biochar properties from corncob rice husk and longan peel were beneficial, resulting in being useful for the soil amendment. It had suitable properties for improving the deteriorated soil structure conditions.
Effect of process conditions on properties of biochar from agricultural residues
Authors: Somparn Waranya , Panyoyai Numpon , Khamdaeng Tipapon , Tippayawong Nakorn , Tantikul Samerkhwan , Wongsiriamnuay Thanasit
Published: April 2020

In northern Thailand, there are a great amount of agricultural residues generated after the harvest, most of which are burned as a means of disposal, affecting the soil for agriculture, wild animals, as well as causing air pollution. One of the solutions that may be beneficial in terms of carbon credit is to turn these agricultural residues into biochar using slow pyrolysis. Biochar is widely accepted biologically derived matter with the ability to contain carbon, large amount of nutrients, adding biodiversity in soils. The attribute of biochar is varied depending on its production process. This research aims to study biochar production conditions and possible attributes with slow pyrolysis process under 100 ml/min nitrogen condition. Two types of agricultural residues including rice husk and corn cob were used, at the process temperature of 300-700 °C. The results indicated that when the temperature was increased, the produced biochar decreased, but different amounts of carbon, electrical conductivity, amounts of inorganic minerals (N, P, K, Mg, Ca, Fe), and alkalinity increased. This enabled the produced biochar to add more carbon to the soil when used, reduce acidity or alkalinity, as well as help the soil to contain more water and other required nutrients for plants better and become a home to microbe. More air ventilation was allowed in the soil, improving its quality.
Briquette production from rice husk by using screw compaction
Authors: Saneewongnaayuttaya Narongrit , Panyoyai Numpon , Khamdaeng Tipapon , Wongsiriamnuay Thanasit
Published: April 2020

Most of the agricultural residues have low density resulting in increasing the cost of storage and transportation. With the reduced volume by the compacting process, density and other properties are increased while the storage and transportation space and cost can be reduced. The effects of screw characteristics on the briquette qualities were measured. The process condition for producing fuel briquettes with screw extruders can be used as renewable energy in the industry. Rice husk was collected and its moisture content was reduced around 8-12%. A screw used as feeding and compacting with a length of 45 centimeters and 19 degrees of screw tip angle. The mold temperatures were around 300-400 degrees Celsius. Three lengths of the screw were tested. While the briquette properties were analyzed, such as density durability, an expansion length, heating value, and moisture content of fuel briquettes after the compression process. The experimental results showed that the suitable compression condition for agricultural materials was in the range of 45.9 cm screw length and mold temperature in the range of 330 - 360 degrees Celsius. The briquettes had a durability of 98.67%, a density of 0.846 g/cm3, expansion ratio of 1.1853 %, the heat value of 3813 cal / g, moisture content after compression of 1.9% w.b. and capacity of 112.8 kg/hr. Increasing the screw length improved the performance of compression, continuous working, and briquette fuel quality. Reducing the screw length required a higher mold temperature, leading to the failure of continuous working, defective machines due to extra burden and deteriorating quality of fuel briquettes.
A scheduling and planning algorithm for microalgal cultivation and harvesting for biofuel production
Authors: San Juan J L G , Mayol A P , Sybingco E , Ubando A T , Culaba A B , Chen W H , Chang J S
Published: April 2020

Microalgae is highlighted as the most feasible bioenergy feedstock because it can produce high amounts of lipids, carbohydrates, and hydrogen, which are necessary compounds for the production of various biofuels, while only requiring minimal water and land due to high photosynthetic efficiency. However, there are technical limitations that negatively influence the mass production of biofuel from algae, making it economically infeasible on a commercial scale. One of these bottlenecks exist in its cultivation. The cultivation method and system are critical in determining the amount and quality of biofuel that may be generated from the microalgae. Additionally, the peak biomass concentration, and productivities for the different compounds and nutrients within microalgae do not occur at the same time. Hence, this work proposes a planning tool for microalgae cultivation systems that incorporates species selection, and cultivation and harvesting approach selection and scheduling, while balancing the minimization of environmental impact and maximization of profit realized. The capabilities of the proposed decision support model is demonstrated through a hypothetical case study. Scenario analyses is likewise conducted to establish an understanding of system behavior and performance over time and under various conditions. The results of the computational experiments show the tools capabilities in simultaneously considering algae growth rates and compound productivities in decision making, for instance biomass species that is able to generate the most of a certain high value fuel is prioritized in cultivation and harvesting.
Developing an artificial neural network model for predicting the growth of Chlorella sorokiniana in a photobioreactor
Authors: Magdaong J B , Culaba A B , Ubando A T , Chang J S , Chen W H
Published: April 2020

Microalgae have been long considered as a potential source of biofuel. Species such as Chlorella sorokiniana can store large amounts of carbohydrates and lipids which can be used to produce biofuels. This paper demonstrates a method for developing an artificial neural network model which can predict C. sorokiniana growth in a photobioreactor. The data used for training the model came from cultivation experiments conducted at the National Cheng Kung University in Taiwan. A feedforward backpropagation ANN model with three inputs (i.e. aeration rate, biomass concentration, and nitrate concentration) and two targets (i.e. biomass concentration and nitrate concentration after 24 hours) was used for this study. Using MATLAB, multiple configurations of this ANN model were created and tested by varying the number of neurons and hidden layers and the training algorithm. Models were initially assessed in terms of their mean square error (MSE) and training performance plots. The models were then further assessed based on their simulation capabilities. After setting the initial biomass and nitrate concentration and aeration profile, the model can already predict the daily biomass and nitrate concentration of C. sorokiniana for the whole cultivation period. The final model selected has one (1) hidden layer and four (4) hidden neurons and it was trained using the Bayesian regularization backpropagation algorithm. For the final selected model, the calculated mean absolute percentage error (MAPE) for the predicted daily biomass and nitrate concentration were all below 7.59% and 3.68% respectively. Thus, the simulation results showed that the final model can accurately predict C. sorokiniana growth at varying aeration profiles. For future studies, this model can be used to determine the aeration profile that can maximize C. sorokiniana growth in a photobioreactor while minimizing aeration costs.
Kinetic modelling study of cyclo-alkane oxidation for transportation fuels
Authors: Tan Johnin , Poon Hiew Mun , Saw Lip Huat
Published: April 2020

Cyclo-alkanes are the major constituents of hydrocarbons in market fuels such as petrol, diesel, and aviation fuels. Diesel fuels derived from bituminous sands have up to 30 % of cyclo-alkanes. Besides that, cyclo-alkanes play a vital role in soot formation as they yield aromatic compounds through dehydrogenation. Thus, it is crucial to include cyclo-alkanes in the formulation of multi-component diesel surrogate fuel models. As a consequence, better prediction in the combustion and emission simulations can be achieved. In this study, a reduced cyclo-alkane kinetic model, namely methyl-cyclohexane (MCH) is developed for diesel engine applications. Here, the detailed MCH model with 1,540 species is served as the base model. The reduced MCH model is derived by performing mechanism reduction using five-stage reduction scheme. Accordingly, a reduced MCH model with 86 species is obtained after the reduction procedures. A 94% reduction in the mechanism size has been successfully achieved. Next, the reduced MCH model is validated against the detailed model with respect to ignition delay (ID) timings in zero-dimensional (0-D) simulations. Computed results by the reduced MCH model are in close agreement with the detailed model, with maximum deviation recorded at 33%. The reduced MCH model developed is ready to be used to represent cyclo-alkanes in multi-component diesel surrogate fuel models.
An energy analysis on the production of torrefied microalgal biomass
Authors: Rivera D R T , Culaba A B , Ubando A T , Chen W H , Chang J S
Published: April 2020

Torrefaction is a process for upgrading raw biomass into an energy-dense fuel. In this study, an energy analysis was conducted to assess the energy consumption in the production of torrefied microalgal biomass. The functional unit of one kilogram torrefied biomass and a system boundary of cradle-to-gate was used. This includes the life cycle stages of cultivation, harvesting, drying, and torrefaction. To include the varying method for the upstream processes, four different scenarios of torrefied biomass production are considered. The result of the analysis revealed that across all four scenarios, the torrefaction stage had a minimal contribution of 1-20% as compared with other life cycle stages. However, even with very optimistic assumptions among all scenarios, the result of the study shows a large energy deficit on the system due to the high energy consumption involved in the cultivation method and even in the drying process. To minimize energy consumption during the cultivation stage, solar lighting was highly recommended. The use of a solar-assisted drying was also advisable to lessen the energy consumption for the drying stage.
On the possibilities to reduce compression ignition engine emissions by controlling the reactivity of diesel-biofuel mixtures
Authors: Miron Lucian , Racovitza Alexandru , Chiriac Radu
Published: April 2020

In most European countries the use of different biodiesel fuels has been proved to be a sustainable method to reduce the pollutant emissions of the operating Diesel engines. An in-debt analysis of combustion characteristics is necessary to give a detailed perspective on the advantages of biodiesel use in compression ignition engines. Among all the essential parameters characterizing the compression ignition engine operation, the ignition delay is the most difficult to be estimated. This parameter offers the possibility to have more control over the combustion process inside the cylinder. This gives the ability to better quantify and ultimately to decrease the pollutant emission for this type of engine. An experimental study has been conducted on a tractor Diesel engine using different biofuel mixtures with 7% and 20% volumetric fractions of fatty acid methyl esters in Diesel fuel. No modifications were made to the fuel injection system in order to have a better image of the direct impact of biodiesel fuel on performance and emissions of the engine. The obtained results showed some reductions of total unburned hydrocarbons and nitrogen oxide emissions over the entire engine speed domain for both tested biodiesel fuels. The estimation of the ignition delay was experimentally carried out and correlated with the properties of the biodiesel fuel; a proper control of the combustion process by fuel reactivity ensured thus the mitigation of carbon monoxide, carbon dioxide and smoke. The link between the experimentally determined ignition delay, mainly it’s reduction, and fuel reactivity is what the present work tries to analyse. A better evaluation of the ignition delay parameter, shorter when using biodiesel mixtures, should lead to better control of combustion and further lowering the exhaust pollutant emissions, without major impact on engine performance. An in-debt analysis of the combustion process starting from the injection characteristics correlated with the fuel reactivity is necessary for shortening the ignition delay and reducing carbon dioxide emissions.
The effect of heat storage to properties and energy recovery of pyrolysis products from agricultural waste
Authors: Chaiwong K , Wichan N , Kuimalee S , Thawonngamyingsakul C
Published: April 2020

The pyrolysis process is the conversion of a biomass into biofuel but the process requires a high amount of external heat in order to increase the temperature of raw material which affects the production costs and energy efficiency. The effect of heat storage to control a temperature on the shell of pyrolysis reactor for the properties and energy recovery of pyrolysis products were considered in this study. Agricultural waste drop tube pyrolysis reactor that was designed into double layer shell wall to contain ceramic bead for heat storage. The parametric test of this study as temperature (350 °C – 550 °C), and biomass type (corncob, coffee grounds and coffee husk) were investigated. This result showed that, the heating rate of the reactor when starting to the setting temperature of the comparison testing (CT) was lower than that of the heat storage testing (HT). It indicated that the energy input for the reactor in case of HT was lower than that from CT. The yield of bio-oil and bio-char of the HT were lower than that of the CT in the same pyrolytic temperature. When increasing temperature for 350 °C to 550 °C effected to decreasing the yield of bio-char while the maximum yield of bio-oil found in the temperature of 450 °C. The heating value of pyrolysis products were increased in the higher temperature. The bio-fuel products from corncob had the higher heating value (HHV) and the energy recovery higher than that from another biomass.
Modelling and simulation of a biomass-based integrated gasification combined cycle with carbon capture: comparison between monoethanolamine and potassium carbonate
Authors: Ghiat Ikhlas , AlNouss Ahmed , Mckay Gordon , Al-Ansari Tareq
Published: April 2020

There are global efforts to reduce the impacts from climate change by limiting increases in temperature to 1.5 °C until 2030, and achieve carbon neutrality by 2050. Thus, it is necessary to design new neutral processes and systems that can meet the varying and growing demands of the population in terms of energy, water and food. One of the main carbon emitters and contributors to climate change is the energy industry, which primarily uses oil and natural gas as an energy source. Fortunately, alternative resources are available such as renewable energies that assemble various environmental and economic benefits. However, more work is necessitated to efficiently utilise these resources by designing, analysing, and optimising existing and new renewable energy-based processes. Therefore, this study proposes a net negative carbon emissions energy system that utilises waste biomass as a feedstock. A biomass based integrated gasification combined cycle combined with a post combustion carbon capture unit by means of chemical absorption is designed and analysed. Two different chemical solvents are used for comparison: Monoethanolamine (MEA) and potassium carbonate. The proposed integrated system is modelled and simulated in Aspen Plus software, and is analysed thermodynamically in terms of energy and exergy efficiencies. A sensitivity analysis is also conducted to assess the effect of varying operating conditions such as flowrate, and temperature of the lean solvent, and the pressure inside the stripper. At design conditions with 80% carbon capture, the system generates 419 kW of electricity and operates at -0.32 kg/kWh of CO2 for both the potassium carbonate and MEA systems.
Numerical simulation of thermal stratification and air quality in an underfloor air distribution system (UFAD)
Authors: Lopez Neil Stephen , Galeos Selena Kay , Calderon Brian Raphael , Dominguez David Roy , Uy Bryan Joseph , Iyengar Rupesh
Published: April 2020

The penetration of underfloor air distribution systems (UFAD) in residential and commercial air conditioning has been rather slow. The most notable applications would be on data centers, where thermal stratification requirements are more demanding. The present study supports and strengthens recent work in the design and development of UFAD systems, by augmenting literature on proper vent positioning and design. In UFAD systems where thermal stratification is more pronounced, significant energy savings may be achieved through proper positioning of supply and return vents. Using a validated numerical simulation model in ANSYS CFX, four UFAD vent layouts are investigated with regards to their implications on thermal stratification and indoor air quality. Results show that not only ventilation layout, but also vent type selection can significantly affect the performance of a UFAD system. Spreading multiple, smaller supply diffusers is preferable than having large supply diffusers on the perimeter of the rooms, both from a temperature distribution and indoor air quality perspective. Notably, air flow is significantly poor in the perimeter layout, causing warmer temperature at the center of the room.
Performance evaluation of a direct evaporative cooling system with hollow fiber-based heat exchanger
Authors: Yan Weichao , Cui Xin , Yang Xiaohu , Jin Liwen , Meng Xiangzhao
Published: April 2020

Direct evaporative cooling systems usually involve the process of spraying water, which may form the drift of water droplets. In addition, the use of circulating water can also lead to the growth of bacteria and molding on the surface of the packing material, affecting the indoor air quality. To address these issues, this paper intends to propose an evaporative cooling method incorporated with hollow fiber membranes. The selective permeation membrane technology allows the membrane module to isolate air from water, which selectively allows only water vapor to pass through, preventing the droplets from entraining bacteria into the air. A mathematical model has been developed to theoretically investigate the heat and moisture transfer between water and air in a hollow fiber membrane-based evaporative cooling module. The governing equations for the pre-cooling IEHX were established and then solved by employing the COMSOL Multiphysics platform. This study validated the model by comparing its outlet air dry bulb temperature and relative humidity against experimental data acquired from literature sources. The numerical model showed good agreement with the experimental findings with maximum discrepancy of 7.0%. The validated model was employed to investigate the influences of the inlet air velocity, inlet air dry-bulb temperature, inlet air relative humidity and geometric parameters on the cooling effect of the evaporative cooling module. Simulation results indicated that the outlet air temperature is greatly affected by the relative humidity of the inlet air under constant inlet air temperature conditions. A higher inlet air relative humidity will result in a higher outlet air dry bulb temperature. In addition, the cooling effectiveness was reduced for a higher inlet air velocity. The design of the hollow fiber membrane-based evaporative cooling module was optimized based on the simulation study.
Convective heat transfer study on the spiral finned tube heat exchanger under various fin pitch arrangements
Authors: Syuhada Ahmad , Afandi Dedi , Sofyan Sarwo Edhy
Published: April 2020

Tube-type compact heat exchangers are one of the most commonly used heat exchangers in the industry. Compact heat exchangers are known for their large surface area to volume ratios allowing more optimal heat transfer rate. This study examines both the coefficient and the rate of convective heat transfer on the outer surface of a tube-type compact heat exchanger. The heat exchanger was configured in the sharp turns and spiral fin which is varied in pitch. The Fin pitches were 1 cm, 2 cm, 3 cm, 5 cm, and 7 cm. The length of the heat exchanger pass was 30 cm with a turn length was 8.2 cm and the total length of the heat exchanger was 6 m. Heat exchangers were made using galvanized pipes with an inside diameter (Di) 20 mm and an outside diameter (Do) of 22 mm, fins are made using aluminium with a thickness of 0.3 mm. Water was maintained at a constant temperature of 80 °C and circulated into the heat exchanger with a flow rate of 0.4 L/s. The air was blown using a fan with varying speeds of 2.4 m/s, 2.8 m/s and 3.4 m/s (the ambient air temperature was 28 °C). The results showed that the highest convection heat transfer coefficient and heat transfer rate occurred in the heat exchanger with a fin pitch of 2 cm, because the turbulence was more optimal and fewer airflow losses. In the heat exchanger with a fin pitch of 3 cm, 5 cm and 7 cm has a large gap between the fins so that turbulence is not optimal while in the heat exchanger with a fin pitch of 1 cm the gap between the fins is too small so that it inhibits the rate of airflow.
Equipment load detection using deep learning for building energy management
Authors: Wei S , Tien P W , Calautit J K , Boukhanouf R , Wu Y
Published: April 2020

The present work will develop a learning-based approach for a demand-driven control system which can automatically adjust the Heating, Ventilation and Air Conditioning (HVAC) setpoints and supply conditions in terms of the actual requirements of the conditioned space. Internal heat gains from typical office equipment, such as computers, printers and kettle will be the focus of this paper. Due to its irregular use during scheduled heating or cooling service periods, an opportunity is offered to reduce unnecessary energy demands of HVAC systems related to the actual use of the equipment and its heat gains, i.e. over- and under-utilization of equipment indicate whether interior spaces are required to be conditioned or not. The work will be using deep learning enabled cameras which can locally run trained algorithms to analyse and take action based on how equipment is utilised in a space. This proposed strategy automatically responds to the equipment usage for optimising energy consumption and indoor conditions. The work will compare the performance of the developed approach with a conventional approach such as the use of static heating or cooling profiles. To highlight its capabilities, the approach is applied to detect the equipment usage in a real open plan office and the output (i.e. deep learning profile) is used as input for a building energy simulation model. The initial results showed that while maintaining thermal comfort levels, up to 19% reduction of the annual energy consumption can be achieved by employing the proposed strategy in comparison to conventionally-scheduled HVAC systems, while only focusing on three types of equipment.
Prediction and optimization of indoor thermal environment and energy consumption based on artificial neural network
Authors: Zhao Yan , Qian Siru , Jing Chengjun
Published: April 2020

Commercial software and simulation tools frequently used by researchers in predicting indoor thermal condition and energy consumption of a green building can ensure high precision, however, the computational process are usually time-consuming and cannot clearly and directly give suggestions for a ‘greener’ design. This paper aimed to develop a novel model based on artificial neural network (ANN) to speed up the simulation and provide optimal design solutions. Training and testing data representing design scenarios of different insulation thickness, shading coefficient, ventilation rate and their corresponding Annual Energy Demand (AED) and Uncomfortable Degree Hours (UDH) value were obtained from a numerical analysis model at first. The deduced ANN model was tested and validated, showing very high accuracy as a predictor for broad range of inputs. Relationship between design parameters and outputs were analysed and presented intuitively. The ANN results directly offered suggestions of minimizing AED and UDH, the optimum solution was to reduce ventilation and increase insulation to the limit, and reduce shading coefficient form base-case 0.5 to approximately 0.2. UDH could be lessened by 4% and AED could be reduced by nearly 29% compared to the base case design in this way.
Study on the influence of different surface colors on energy consumption of mall in hot summer and cold winter areas
Authors: Qian Siru , Long Enshen , Guo Shurui , Zhang Ying , Zhao Yan
Published: April 2020

China’s energy consumption of building operation is increasing year by year. The characteristic of building envelope is an important factor affecting energy consumption, including color and material. This paper based on the analysis of the relationship between the heat balance of the enclosure structure and the solar radiation, the micro effects of different color on the daily and hourly air conditioning energy consumption of the building are studied, and the energy saving mechanism is further divided Analysis. We found that: through the simulation calculation, the cooling load accounts for a large proportion in the hypermarket, and the number of days with cooling demand accounts for 361 days., the cooling energy consumption from May to October accounts for 100% of the total energy consumption. When the color of the coating applied on the building surface is from deep to shallow, with the increase of daily cooling consumption, the larger the number of points in the energy saving of air conditioning, the more significant the energy saving effect. The change of paint color mainly affects the energy saving rate of air conditioning when there is solar radiation in the supermarket. From the micro dimension, with the increase of solar radiation, the trend of absolute energy saving and relative energy saving effect of building air conditioning cooling load is the same.
Forced convection boiling heat transfer inside helically-coiled heat exchanger
Authors: Haryoko Luthfi A F , Kurnia Jundika C , Sasmito Agus P
Published: April 2020

For decades, forced convection boiling heat transfer has been considered as one of the most efficient type in the heat transfer mechanism. It has been widely utilized in heat transfer equipment of various industries. Meanwhile, helically-coiled heat exchanger has been commonly utilized in numerous industrial applications. Thus, there is an interest to utilize forced convection boiling heat transfer in helically-coiled heat exchanger. Boiling phenomenon inside helically-coiled tube is more complex as compared to the straight tube due to the secondary flow induced by centrifugal force. This study investigates flow boiling heat transfer performance of water-vapor inside helically-coiled tube by using computational fluid dynamic approach. A Eulerian-Eulerian two-fluid model is used to capture interphase exchange forces and heat transfer between liquid and vapor phase. Wall boiling model is adopted to take into account the boiling condition in the vicinity of the wall. The developed model is then validated against the previously published experimental data. Good agreement for the outlet vapor quality and pressure drop between numerical study and experimental measured value is achieved. The result reveals that the boiling starts at the inner wall of the tube (φ=450°) due to the presence of secondary flow induced by coil curvature. The relationship between HTC and vapor quality along the helically-coiled tube are discussed and evaluated. This study serves as a guideline for future study on forced convection boiling heat transfer in the helically-coiled tube.
Solar decathlon Europe 2019: The resilient nest as a solar powered and energy efficiency rooftop house for urban density
Authors: Chanto Kasan , Mahasuwanchai Peerasit , Eakintumas Warawit , Lairat Choophong , Thavornsettawat Nutkitti , Tanthanawiwat Kittipat , Wongthavornman Kunnapat , Pulngern Tawich , Chayavanich Nattavut , Wiputthanupong Wilaiwan , Pansuwan Waraluk
Published: April 2020

This paper presents the design concept, and monitoring results of the Resilient Nest which was participated in the Solar Decathlon Europe 2019 competition. The Resilient Nest has been designed as a lightweight rooftop house which can be placed on top of a row house in Bangkok, Thailand to respond an increased urban density. This additional rooftop house does not only increase the living space on an existing building, but it also ensures that the existing building become more viable, comfortable and eco-friendly. A solar energy, both electrical energy from photovoltaic panel and thermal energy from solar collector which are renewable energy, can accommodate the Resilient Nest rooftop as well as the existing building. The monitored results during 10 days competition results showed that the energy balance of the Resilient Nest was net positive of 171.81 kWh which was the highest value compared to other 9 competitors. The Resilient Nest generated 277.78 kWh as the first runner-up for the Energy generation. The power consumption for the HVAC system of the Resilient Nest during 10 days was only 37.65 kWh. Comparing to the suitable air conditioned house recommended by the Government Public Relations Department of Thailand, the Resilient Nest consumed over 14 times less energy because of its high performance thermal insulation, heat recovery system and solar thermal system. The low HVAC power consumption gave high performance for indoor comfort. As a result, the Resilient Nest won a second place in Comfort conditions contest.
Embodied energy and life-cycle greenhouse gas of conventional and the resilient nest house
Authors: Tanthanawiwat Kittipat , Chanto Kasan
Published: April 2020

This study performs the comparative assessment of the initial embodied energy and life-cycle greenhouse gas (GHG) emission between Thailand’s conventional reinforced concrete (RC) house and the Resilient Nest house which was designed and constructed for the Solar Decathlon Europe 2019 competition. The Resilient Nest is a prototype for the sustainable house and an alternative building in perspectives of renewable-energy, green building, energy efficient, and net-zero waste house. This house was designed and constructed by KMUTT team with an integration design of cosy house and the green economic system concept which have become a major concern nowadays for mitigating the environmental impacts due to an urban development. The environmental sustainability performance was investigated. All the materials used for convectional and the Resilient Nest houses as well as the energy used for the construction, were evaluated to illustrate the embodied energy (MJ) and GHG emission (kgCO2eq). As per square meter of the usable space of the house, the results show that the Resilient Nest house has embodied energy of 2,302.2 MJ/m2 and life-cycle greenhouse gas is about 122.22 kgCO2eq. Whereas, the conventional house is illustrated the consequences of embodied energy of 1,400 to 3,580 MJ/m2 and 300 – 4,625 kgCO2eq per square meter. The Resilient Nest house clearly proofs the minimizing environmental impact than the conventional house. The designation of materials was considered as an important parameter. In addition, as the whole life-cycle, the higher impact from the initial phase would be minimized and compensated during the service phase. To enhance the ultimate goal of the Resilient Nest house, recommendations for further improvement of the prototype house have been discussed.
Numerical simulation of single-sided natural ventilation: Impacts of balconies opening and depth scale on indoor environment
Authors: Izadyar Nima , Miller Wendy , Rismanchi Behzad , Garcia-Hansen Veronica
Published: April 2020

Heating Ventilation and Air Conditioning (HVAC), including, Mechanical ventilation (MV) in the building sector accounts for around 40% of electricity consumption and a large percentage of Greenhouse Gas (GHG) emissions. Natural ventilation (NV), as an alternative method, assist in decreasing energy consumption as well as harmful emissions. Balconies, a common architectural element in high rise residential buildings, could enhance NV and reduce reliance on mechanical ventilation in cooling dominant climates. Indoor air velocity and distribution, IAV and IAD, due to NV is less predictable than MV, and the impacts of balcony geometry on IAV and IAD profile have not yet been classified. This study, focusing on single-sided ventilation apartments, seeks to determine to what extent balcony depth and door opening area impacts on the indoor environment of the attached living area. For this, 3D – steady-state Computational Fluid Dynamics (CFD) simulations were conducted using ANSYS Fluent. The simulation results were validated against measured data in a full-scale experimental study in a residential building in subtropical Brisbane, Australia. Five different openings and nine depth scenarios were modelled, with results showing variances in indoor mean air velocity and temperature. The outcomes reveal the impacts of opening and depth scales on IAD profile, as well as IAV and temperature magnitude at the attached indoor area. Although the defined scenarios could not reach a firm conclusion, the findings of simulation reject the shallowest balcony scenario (depth less than 2 m) due to weak IAD. Besides, the results show that a small opening could lead to an acceptable IAV at the attached indoor area. Results also suggest that further research on the indoor distribution of temperature and air velocity, consequently neutrality based on thermal comfort model, may provide further clarity on the effect of geometric factors on occupant comfort through NV.
Price allocation of transmission line usage in open access system using mega volt ampere kilometer and mega volt ampere cost method for integrated Nepal power system
Authors: Acharya Prannab , Shrestha Namrata Tusuju , Mishra Brajesh , Zareipour Hamidreza , Shrestha Pramish
Published: April 2020

The price allocation of transmission line usage for an open access system considering Integrated Nepal Power System (INPS) has been discussed in this paper using the MVA (mega volt ampere) - KM (kilometer) and MVA cost method. The price allocation has been compared for INPS (Integrated Nepal Power System) and IEEE 14 bus system. The transmission line costs in IEEE 14 bus system is based on average construction and operation cost whereas, the costs in the INPS is an actual cost of the present transmission system. The price has been first calculated for different bus with reference to slack bus and for different bilateral and multilateral transactions, using MW KM - MW cost and MVA KM - MVA cost methods. The active and apparent powers for the base case and transaction cases have been calculated using Newton Raphson Method. The prices from MVA KM - MVA cost method are higher than MW KM - MW cost method for both bilateral transaction and multi-lateral transaction indicating more reactive power support in addition to the real power loading due to transactions in the system. The result shows that MVA KM - MVA cost method requires incentives for reactive power support to the system such as INPS.