ADABATIC TWO-PHASE FLOW IN VERTICAL RECTANGULAR TEST SECTION

Vikrant Chalgeri,Tae Hyeon Kim(김태현),Ji Hwan Jeong(정지환) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.5

Adsorption performance of standard biochar materials against volatile organic compounds in air: A case study using benzene and methyl ethyl ketone

Vikrant, Kumar,Kim, Ki-Hyun,Peng, Wanxi,Ge, Shengbo,Sik Ok, Yong Elsevier 2020 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.387 No.-

<P><B>Abstract</B></P> <P>Recently, biochars have been proposed as highly efficient and low-cost media for the adsorptive removal of various hazardous compounds. However, there is a dearth of literature focusing on adsorption performance of biochars against gaseous volatile organic compounds (VOCs). In light of this limitation, the adsorption performances of 12 standard biochars made of six different raw materials (i.e., <I>Miscanthus</I> straw pellets, oil seed rape straw pellets, rice husk, sewage sludge, soft wood pellets, and wheat straw pellets) at two pyrolysis temperature conditions (i.e., 550 °C and 700 °C) were investigated against two model gaseous VOCs (i.e., benzene and methyl ethyl ketone (MEK)) at 1 Pa each. The breakthrough volume (BTV) and partition coefficient (PC) of benzene at 10% BTV, when measured for all these biochars, varied from 1.4 to 10 L atm g<SUP>−1</SUP> and 6.E-04 to 1.4E-02 mol kg<SUP>−1</SUP> Pa<SUP>−1</SUP>, respectively. Similarly, their counterpart values for MEK were 1.8 to 40 L atm g<SUP>−1</SUP> and 1.E-03 to 2.E-03 mol kg<SUP>−1</SUP> Pa<SUP>−1</SUP>, respectively. The largest adsorption capacity values for benzene (2.9 mg g<SUP>−1</SUP>) and MEK (43 mg g<SUP>−1</SUP>) were observed from the soft wood pellet biochar prepared at 700 °C (SWP700) and rice husk biochar prepared at 550 °C (RH550), respectively. The results indicate that most biochars adsorbed MEK preferentially over benzene. The adsorption of MEK appeared to be primarily influenced by surface features and composition of each specific biochar, while that of benzene was proportionate to their surface area. Overall, the results of this investigation are expected to help establish technical standards for effective removal of gaseous VOCs by biochars.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Biochar is a carbon-based material that can be utilized as an adsorbent. </LI> <LI> 12 standard biochars were analyzed for the capture of gaseous benzene and MEK. </LI> <LI> Rice husk biochar prepared at 550 °C showed the highest capacity of 43 mg g<SUP>−1</SUP> for MEK. </LI> <LI> Soft wood pellet biochar prepared at 700 °C showed the best performance for benzene. </LI> <LI> Most of the analyzed biochars preferably adsorbed MEK as compared to benzene. </LI> </UL> </P>

Flow Regime Transition Criteria for Vertical Downward Two-Phase Flow in Rectangular Channel

Vikrant Siddharudh Chalgeri,Ji Hwan Jeong 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12

A novel approach for prediction of surface roughness in turning of EN353 steel by RVR-PSO using selected features of VMD along with cutting parameters

Vikrant Guleria,Vivek Kumar,Pradeep K. Singh 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.6

The abrupt changes in tool-workpiece interaction during machining process induce variation in the surface quality of work material. These interactions include built-up edge formation and their break-off, environmental conditions (use of coolant, rise of temperature etc.), material imperfections, improper structural fitness of machine & tool components, etc. This study presents prediction of surface roughness in turning of EN353 steel implementing the variational mode decomposition (VMD) for processing the vibration data, followed by estimation of the surface roughness using the relevance vector regression (RVR) optimized by particle swarm optimization (PSO). The raw vibration data has been decomposed in five discrete sets of frequency components known as variational mode functions (VMFs). A set of twenty-one statistical features in each three axes have been extracted for raw data and each VMF. The RVR has been trained using these 21×3 = 63 features and 3 cutting parameters – cutting speed, feed depth of cut. The RVR has also been trained separately using top 5 features selected through RreliefF algorithm. The optimal decomposition level has been determined to minimize the noise and predict the surface finish accurately. The results obtained in 1st VMF (high frequency, low amplitude) using its top 5 features for prediction have been found to be reliable with higher prediction accuracy.

Flow Regime Transition Criteria for Vertical Downward Two-Phase Flow in Rectangular Channel

Vikrant Siddharudh Chalgeri,정지환 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.2

Narrow rectangular channels are employed in nuclear research reactors that use plate-type nuclear fuels,high heat-flux compact heat exchangers, and high-performance micro-electronics cooling systems. Twophase flow in narrow rectangular channels is important, and it needs to be better understood because itis considerably different than that in round tubes. In this study, mechanistic models were developed forthe flow regime transition criteria for various flow regimes in co-current air-water two-phase flow forvertical downward flow inside a narrow rectangular channel. The newly developed criteria werecompared to a flow regime map of downward air-water two-phase flow inside a narrow rectangularchannel with a 2.35-mm gap width under ambient temperature and pressure conditions. Overall, theproposed model showed good agreement with the experimental dat

Metal-organic framework (MOF)-based advanced sensing platforms for the detection of hydrogen sulfide

Vikrant, Kumar,Kumar, Vanish,Ok, Yong Sik,Kim, Ki-Hyun,Deep, Akash Elsevier 2018 Trends in analytical chemistry Vol.105 No.-

<P><B>Abstract</B></P> <P>Hydrogen sulfide (H<SUB>2</SUB>S) is and a colorless, corrosive, flammable, and toxic gas with a characteristic rotten egg smell. Although its detection can be conducted by conventional methods (like gas chromatography), highly effective and sensitive detection of H<SUB>2</SUB>S has been realized with the usage of various nanomaterials (e.g., carbon nanostructures, metal nanoparticles, metal oxide nanoparticles, and quantum dots). Metal-organic frameworks (MOFs), as employed for such applications either in their pristine or modified forms, have been recognized as the effective media for sensing of H<SUB>2</SUB>S due to synergistic effects in addition to their well-known merits (e.g., the large specific surface). This review has been organized to describe the potential applicability of MOF-based sensing against H<SUB>2</SUB>S through comparative evaluation of their capability against other materials or tools. We also discuss the present obstacles and outline the future scope of research on MOF-based sensing tools.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The monitoring and control of inordinately odorous gases like hydrogen sulfide, H<SUB>2</SUB>S is important. </LI> <LI> Conventional methods of H<SUB>2</SUB>S suffer from many demerits such as the need for complex instruments. </LI> <LI> Metal-organic frameworks (MOFs) and hybrids/composites have high sensing potential for H<SUB>2</SUB>S. </LI> <LI> This review highlights recent advances and factors associated with the sensing of H<SUB>2</SUB>S by MOFs. </LI> <LI> Our discussion attempts to uncover the present obstacles and challenges in this field of research. </LI> </UL> </P>

Engineered/designer biochar for the removal of phosphate in water and wastewater

Vikrant, Kumar,Kim, Ki-Hyun,Ok, Yong Sik,Tsang, Daniel C.W.,Tsang, Yiu Fai,Giri, Balendu Shekhar,Singh, Ram Sharan Elsevier 2018 Science of the Total Environment Vol.616 No.-

<P><B>Abstract</B></P> <P>During the past decade, biochar has attracted immense scientific interest for agricultural and environmental applications. A broad range of biochars with advantageous properties (e.g., high surface area, flexible architecture, and high porosity) has been developed for pollution abatement. Nevertheless, biochar suffers from certain drawbacks (e.g., limited sorption capacity for anions and poor mechanical properties) that limit their practical applicability. This review focuses on recent advancements in biochar technology, especially with respect to its technical aspects, the variables associated with removing phosphates from water, and the challenges for such abatement. The attention paid to the specific remediation of phosphate from water using biochar is limited (n=1114 – Scopus) compared to the application of biochar to other common water pollutants (n=3998 – Scopus). The subject warrants immediate rigorous research because of the undesirable effects of excess phosphate in water bodies. This review will thus facilitate the construction of a roadmap for further developments and the expansion of this challenging area of research.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The control of excess aqueous phosphate is a crucial task in environmental management. </LI> <LI> Elevated levels of phosphate in water systems can increase the costs of water treatment. </LI> <LI> The easy fabrication and structural flexibility of biochars ensure the efficient removal of P. </LI> <LI> We propose various options to apply biochars in the area of phosphate sorption and separation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Evaluation of Indian Mustard Genotypes to Heat Stress in Irrigated Environment - Seed Yield Stability and Physiological Model

Vikrant Singh,CRam Bhajan 한국작물학회 2016 Journal of crop science and biotechnology Vol.19 No.5

Indian mustard is mostly targeted for commercial cultivation as an early-sown or late-sown crop with the expectation of higher seed yield and oil content. With this lacuna, 45 genotypes were analyzed for yield traits by growing them as early, timely, and late-sown crops over 2 years in Pantnagar, India. The results of the ‘Eberhart and Russell Model’ and ‘GGE Biplot’ analyses were in accordance to each other but Eberhart and Russell’s model was more appropriate for judging the genotype(s) to environment specificity/adaptation while GGE Biplot was the best approach to evaluate the concerned environments for their discriminating power to genotypes. Inverse and counteracting relationships were observed among model parameters, i.e., crop growth rate (C), partitioning coefficient (P), and duration of reproductive phase (Dr) with seed yield and oil content. Seed yield was positively (P ≤ 0.01) related to all related traits except Dr, while oil content was positively (P ≤ 0.01) related to only Dr. Both C and P contributed to final yields, but P had a greater contribution particularly under terminal heat stress.

Graphene materials as a superior platform for advanced sensing strategies against gaseous ammonia

Vikrant, Kumar,Kumar, Vanish,Kim, Ki-Hyun The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.45

<P>Ammonia (NH3) is an uncolored, toxic, corrosive, and reactive gas with a characteristic pungent stench. To date, quantitative analysis of NH3 concentrations have been made using conventional techniques (<I>e.g.</I>, ion chromatography). In light of the complications involved in such applications, efforts have been made to develop detection methods of NH3 that are more sensitive and selective. In this respect, graphene-based gas sensors have attracted widespread attention because of graphene's distinctive electrical characteristics (<I>e.g.</I>, low electrical signal noise and great mobility) and large surface area. This review article was designed to evaluate the potential usage of graphene-based gas sensors for effective detection of NH3. We aim to understand the recent advances in this challenging area of research by critically analyzing various experiments and comprehending their practical implications. This review critically compares the performance of graphene-based NH3 sensors with those of other nanomaterials for a broader understanding of the field. Also, we summarize the future prospects for advancement of graphene technology for NH3 sensing.</P>

Metal-organic frameworks (MOFs): potential and challenges for capture and abatement of ammonia

Vikrant, K.,Kumar, V.,Kim, K. H.,Kukkar, D. Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.44

<P>Metal-organic frameworks (MOFs) have potential as air quality treatment media for various gaseous pollutants (e.g., ammonia) through diverse mechanisms (capture and catalytic degradation). A broad range of MOFs have been developed with numerous advantageous properties (e.g., high surface area, high degree of porosity, intrinsically tunable chemical structure, flexible architecture, and multifunctional properties) to meet strict air quality metrics. Nevertheless, the practical use of these novel materials has also been restricted due to certain drawbacks including high fabrication costs, poor selectivity, low capacity, and difficulties in recycling/regeneration. This review was organized to highlight the recent advancements in MOF technology for the mitigation of ammonia. The article aims to expand the use of MOFs in air quality treatments by identifying the research gaps in associated fields.</P>