Joel Songok - Academia.edu (original) (raw)

Papers by Joel Songok

International Paper and Coating Chemistry Symposium, 2012

While drying of paper and paper coatings is expensive, with significant energy requirements, the ... more While drying of paper and paper coatings is expensive, with significant energy requirements, the rate controlling mechanisms are not currently fully understood. Two two-dimensional models are used as a first approximation to predict the heat transfer during hot air drying and to evaluate the role of various parameters on the drying rates of porous coatings. The models help determine the structural limiting factors during the drying process, while applying for the first time the recently known values of coating thermal diffusivity. The results indicate that the thermal conductivity of the coating structure is not the controlling factor, but the drying rate is rather determined by the thermal transfer process at the structure surface. This underlines the need for ensuring an efficient thermal transfer from hot air to coating surface during drying, before considering further measures to increase the thermal conductivity of porous coatings.

Waste Management, 2021

This paper presents a multi-objective optimization (MOO) of waste-to-energy (WtE) to investigate ... more This paper presents a multi-objective optimization (MOO) of waste-to-energy (WtE) to investigate optimized solutions for thermal, economic, and environmental objectives. These objectives are represented by net efficiency, total cost in treating waste, and environmental impact. Integration of the environmental objective is conducted using life cycle assessment (LCA) with endpoint single score method covering direct combustion, reagent production and infrastructure, ash management, and energy recovery. Initial net efficiency of the plant was 16.27% whereas the cost and environmental impacts were 75.63 €/ton-waste and -1.21 × 108 Pt/ton-waste, respectively. A non-dominated sorting genetic algorithm (NSGA-II) is applied to maximize efficiency, minimize cost, and minimize environmental impact. Highest improvement for single objective is about 13.4%, 10.3%, and 14.8% for thermal, economic, and environmental, respectively. These improvements cannot be made at once since the objectives are conflicting. These findings highlight the significance role of decision makers in assigning weight to each objective function to obtain the optimal solution. The study also reveals different influence among decision variable, waste input, and marginal energy sources. Finally, this paper underlines the versatility of using MOO to improve WtE performance regarding the thermal, economic, and environmental aspects without requiring additional investment.

ACS Applied Materials & Interfaces, 2016

Paper-based microfluidic devices have received considerable interest due to their benefits with r... more Paper-based microfluidic devices have received considerable interest due to their benefits with regards to low manufacturing costs, simplicity and the wide scope of applications. However, limitations including sample retention in paper matrix and evaporation as well as low liquid flow rates have often been overlooked. This paper presents a paper-based capillary-driven flow system that speeds up flow rates by utilizing narrow gap geometry between two parallel surfaces separated by a spacer. The top surface is hydrophobic while the bottom surface is a hydrophobic paper substrate with a microfluidic channel defined by a hydrophilic pathway, leaving sides of the channel open to air. The liquid flows on the hydrophilic path in the gap without spreading onto the hydrophobic regions. The closed channel flow system showed higher spreading distances and accelerated liquid flow. An average flow rate increase of 200% and 100% was obtained for the nanoparticle coated paperboard and the blotting papers used, respectively. Fast liquid delivery to detection zones or reaction implies rapid results from analytical devices. In addition, liquid drying and evaporation can be reduced in the proposed closed channel system.

Journal of Micromechanics and Microengineering, 2017

Paper-based microfluidics is an emerging field focused on creating inexpensive devices, with simp... more Paper-based microfluidics is an emerging field focused on creating inexpensive devices, with simple fabrication methods for applications in various fields including healthcare, environmental monitoring and veterinary medicine. Understanding the flow of liquid is important in achieving consistent operation of the devices. This paper proposes capillary models to predict flow in paper-based microfluidic channels, which include a flow accelerating hydrophobic top cover. The models, which consider both non-absorbing and absorbing substrates, are in good agreement with the experimental results.

Microfluidics and Nanofluidics, 2016

This paper describes two methods for controlling capillary-driven liquid flow on microfluidic cha... more This paper describes two methods for controlling capillary-driven liquid flow on microfluidic channels. Unlike flow driven by external forces, capillary-driven flow is dominated by interfacial phenomena and, therefore, is sensitive to the channel geometry and chemical composition (surface energy) along the channel. The first method to control fluid flow is based on altering surface energy along the channel through regulation of UV irradiation time, which enables adjusting the contact angle along the fluid path. The slowing down (delay) of the liquid flow depends on the stripe length and its position in the channel. Using this technique, we generated flow delays spanning from a second to over 3 min. In the second approach, we manipulated the flow velocity by introducing contractions and expansions in the channel. The methods used herein are inexpensive and can be incorporated to the microfluidic channel fabrication step. They are capable of controlling liquid flow with precise time delays without introducing the foreign matter in the fluidic device.

The European Physical Journal E, 2016

Greenhouse Gases: Science and Technology, 2011

The years ahead will show whether CO 2 mineral sequestration can be developed to a unit scale of ... more The years ahead will show whether CO 2 mineral sequestration can be developed to a unit scale of the order of 1 Mt/a CO 2 storage around the year 2020, offering additional large-scale carbon capture and sequestration (CCS) capacity besides underground CO 2 sequestration. Motivated by the slow deployment of large-scale underground storage of CO 2 or simply the availability of large amounts of suitable minerals, progress on mineral sequestration is being steadily made and reported by an increasing number of research teams and projects worldwide. Other well-documented advantages of the method are that it offers leakage-free CO 2 fi xation that does not require post-storage monitoring and an overwhelmingly large capacity is offered by mineral resources available worldwide, besides the feature that the chemical conversion releases signifi cant amounts of heat. As recognized more recently, it also offers the possibility to operate with a CO 2-containing gas directly, removing the expensive CO 2 separation step from the CCS process chain. Moreover, the solid products can be used in applications ranging from land reclamation to iron-and steelmaking. With the technology overview given in the Intergovernmental Panel on Climate Change (IPCC) Special Report on CCS (2005) as a reference point, the method is reviewed and its capacity, weaknesses, and strengths are reassessed. The state-of-the-art after twenty years of R&D work as refl ected by ongoing development work inside and outside laboratories is summarized, illustrating the future prospects of CO 2 mineralization within a portfolio of CCS technologies under development worldwide. Current developments include an increasing number of patents and patent applications and a trend toward scale-up and demonstration.

ACS Applied Materials & Interfaces, 2014

Journal of Colloid and Interface Science, 2014

Mechanisms controlling short time water absorption and the effect of temperature on water absorpt... more Mechanisms controlling short time water absorption and the effect of temperature on water absorption into paper were investigated by analyzing previously published data. A dynamic contact angle effect caused by contact line friction explained the liquid uptake dynamics at short times. The water absorption rate increase with temperature is suggested to be controlled by the molecular processes occurring in front of the advancing liquid front. The increase in the non-equilibrium vapor pressure at air-liquid interface leads to higher water molecule adsorption onto fibers and associated lowering of the solid-gas interfacial tension, thereby increasing the wetting velocity and water absorption. The classical Lucas-Washburn equation was found to be inadequate for predicting water absorption into paper both at short times and as a function of temperature.

Industrial & Engineering Chemistry Research, 2012

ABSTRACT The influence of the coating composition of a porous paper coating on the evaporation ra... more ABSTRACT The influence of the coating composition of a porous paper coating on the evaporation rate of water contained in the sample has been studied experimentally. For low-content latex samples, drying was found to be mainly controlled by capillarity, perhaps also in the form of thin film pore surface feature/wall wetting, which drew water from the connected pores to the drying surface or near the surface. This led to a lengthy constant drying rate period (CDRP) where nearly 70% of the saturated water was evaporated. High-content latex samples, characterized by low porosity and permeability showed shorter CDRP and lengthy falling drying rate period. The drying rate curve varied linearly with time in the CDRP and with the square root of time in the falling rate period, indicating a diffusive controlled mechanism. Low latex content samples took less time to dry, which can be inferred to mean they require less drying energy.