Dr Aditya Putranto

Senior Lecturer
School of Engineering

aditya.putranto1@monash.edu
+603 5515 9786
Room 5-4-47
ORCID

Personal statement

Dr Aditya Putranto is currently Senior Lecturer in Chemical Engineering at Monash University Malaysia. He has 15 year research and teaching experience internationally, including in UK, Australia, China and Indonesia. Previously, he was Lecturer in Chemical Engineering at Queen's University Belfast UK. He was also Research Fellow at Monash University Australia. He obtained his Bachelor of Chemical Engineering from Bandung Institute Technology Indonesia where he was awarded "the highest GPA". Subsequently, he obtained Master of Chemical Engineering from Bandung Institute of Technology Indonesia (with GPA of 4 out of 4) and Master of Science in Food Engineering from University of New South Wales Australia (High Distinction). Following his PhD study at Monash University Australia, his PhD was conferred in 2013. Due to his excellence in PhD and high quality thesis, he was awarded "Mollie Holman Medal" by Vice Chancellor Monash University. This medal is only presented to one receipient per year in each faculty. In terms of teaching, he has experience of teaching all core units in chemical engineering as well as units related to modeling/simulation. His teaching quality has been evidenced by Outstanding score of Teaching Evaluation Questionnaire. He is currently Fellow of Higher Education Academy UK. His teaching style focuses on realising the abstract concepts by making use of examples and case-studies as well as establishing simulation to aid the students' understanding. He has further developed and implemented "Design-based learning" to help students integrate the concepts to produce processes and products. He has also experience in curriculum development by improving course content, innovating the delivery method and developing student-centred assessment. As for research, his experience and expertise lies in drying technology, food engineering and transport phenomena. To date, he has published one book (published by Cambridge University Press United Kingdom), three book chapters and 46 Scopus - peer reviewed journal papers. He published in hard-core chemical and food engineering journals including AIChE Journal, Chemical Engineering Science, Chemical Engineering Research and Design, Chemical Engineering Processing: Process Intensification, Industrial Engineering Chemistry Research, Journal of Food Engineering, Food Research International, Food and Bioproducts Processing and Drying Technology. He has published three journal papers in AIChE Journal and one of them has been highlighted as "the Hottest Paper" by Wiley. As a recognition of his research excellence, he has been awarded with "Young Drying Scientist Award", "Outstanding Drying Book Award", "the Best Paper". His research has also been presented as keynote speech at International Drying Symposium as well as Asia Pacific Drying Conference. He is currently Associate Editor of International Journal of Food Engineering. He also has been invited as external examiner of HDR (higher degree research) theses by UNSW, Curtin University and Queensland University of Technology as well as serving as peer-reviewer of reputable journals.

Academic degrees

  • PhD in Chemical Engineering (awarded Mollie Holman Medal for the best PhD thesis), Monash University Australia, 2013
  • MSc in Food Engineering, UNSW Australia, 2007
  • Master in Chemical Engineering, Bandung Institute of Technology, 2004
  • Bachelor of Chemical Engineering, Bandung Institute of Technology, 2003

Professional affiliations

Member of International Professional Bodies

  • Higher Education Academy UK, Fellow

Research Interests

  • Drying Technology
  • Food Engineering
  • Transport Phenomena
  • Process Modeling and Simulation

Research Projects

Title: Intensified drying processes of fruits and vegetables: application of microwave-drying, ultrasonic-

assisted drying, infrared-heating drying

Process intensification is commonly implemented in engineering practice to result in higher energy efficiency. In this study, the applicability of reaction engineering approach (REA) to model several process intensification schemes of drying is assessed. The REA was employed to model microwave, ultrasonic-assisted and infrared-heating drying. For microwave and infrared-heating drying, a new formulation of equilibrium activation energy was introduced. In all schemes, the relative activation energy, generated from one accurate convective drying run, was coupled with the equilibrium activation energy to yield the activation energy. Combined with the suitable heat balance, the REA is accurate to model these enhanced drying processes. Benchmarks against diffusion-based model showed that the REA yielded a closer agreement toward the experimental data. While the REA is accurate, the REA is very efficient in generating the drying parameters. The REA-based model is readily applied in industrial settings as a basis for fine-tuning the process to manufacture the products with the desirable quality.

Title: Numerical simulation of mono-disperse droplet spray dryer: Coupling distinctively different sized chambers

The discrete phase model (DPM) has been widely used in CFD simulations to track discrete particles or droplets in a continuum fluid filed. This powerful technique, however, may face tremendous difficulty in tracking droplets flying through chambers with significantly different sizes. In such cases, it becomes very challenging to develop effective mesh for the big and small chambers together with the transition zone that can ensure solution convergence within reasonable computational time. In this work, a systematic method is introduced to tackle this problem. This method allows simulation of different sized chambers separately to avoid the meshing difficulty. A unique coupling approach offers smooth transition of droplets from one chamber to the other with rigorous conservation of their mass, energy and momentum. The effectiveness of the method is demonstrated through the simulation of skim milk droplet drying in a mono-disperse droplet spray dryer (MDSD), where droplets must pass through a small dispersion chamber before entering the main big drying chamber. For the first time, droplet drying process from exiting nozzle to the arrival at the dryer outlet can be simulated. The new model can be used in the future to optimize the spray drying process.

Title: Solute migration during drying of dairy droplets

Surface composition of dairy powders plays an important role in determining the functionality. However, the surface composition may be different from the bulk composition because of component migration during drying. In this study, a comprehensive mathematical model has been developed to describe the phenomena. To the best of our knowledge, it is the first mathematical model which predicts the dynamics of surface composition during drying. The model consists of a set of equations of conservation of mass of water, lactose, protein, and fat as well as conservation of heat and momentum in which the effects of diffusion induced material migration and surface activity are incorporated. This model is applicable to describe the kinetics of surface composition of dairy droplets during drying. It suggests that both diffusion and protein surface activity govern the component segregation during drying. The study indicates that the model implementing the measured initial surface composition as the initial conditions generates more realistic profiles than the one using the bulk composition. The modeling confirms that the difference between the surface and bulk composition that occurs prior to drying is not primarily governed by diffusion, but the emulsion's atomization behavior seems to play an essential role in the overrepresentation of fat.

Title: Energy-saving combination of nitrogen production, ammonia synthesis and power generation

A novel integration of N2 production, NH3 synthesis, and power generation systems is designed to efficiently convert H2 to NH3. The integrated system employs the principles of exergy recovery and process integration to achieve high energy efficiency. The high-purity N2 output by the N2 production module is reacted with H2 in an NH3 synthesis module to produce NH3. In addition, O2-rich gas, which is a by-product, is utilized as an oxidant in the power-generation module. A single column is adopted in the N2 production module, and the feed stream is split into two and fed to the middle and bottom of the column. In our tests with the N2 production module, the two operating parameters of bottom-feed ratio and refed-stream ratio were evaluated in terms of the energy consumed, N2 purity, and O2 molar fraction in O2-rich gas. Compared with previous studies on N2 production systems, our N2 production module can reduce energy consumption by about 43% (3.27 MW compared with 5.76 MW to produce 1 tmol-N2 h−1). In the NH3 synthesis and power generation module, the two operating parameters of conversion rate per pass and purged-stream ratio are also evaluated. The calculation results show that a high conversion rate per pass and low purged-stream ratio increase the total energy efficiency, which includes NH3 production efficiency and power generation efficiency. The highest total energy efficiency that can be achieved by the integrated system is 66.92%, which includes a NH3-production efficiency of 66.69% and a net power generation efficiency of 0.23%.

Title: Drying and denaturation kinetics of beta-lactoglobulin during drying

Beta-Lactoglobulin (β-Lg) is the major fraction of whey protein that comprises more than 65%. Therefore, denaturation of β-Lg during drying can affect the protein functionality where the whey protein is used as an ingredient in food products. This study was carried out to understand the drying and denaturation kinetics of β-Lg during the drying process. A convective drying environment was used to predict the moisture content and temperature kinetics of the drying droplets of β-Lg using Reaction Engineering Approach (REA) models. The predicted values were then coupled with the first order reaction equation to determine the denaturation kinetics. Single droplets of β-Lg (10% w/v; 1.5 ± 0.1 mm initial diameter) were dried at two different temperatures (65 °C and 80 °C) at a constant air velocity (0.5 m/s) for 10 min. The real time denaturation of β-Lg protein was quantified at different drying stages using a reversed phase HPLC. These experimental data from single droplet drier, and HPLC were used to validate the model predictions. The REA model predictions fitted well with the experimental data for moisture-time (±5.70% error) and temperature-time (±3.50% error) profiles. Similarly, the first order kinetics model was also able to predict the denaturation kinetics of β-Lg protein with an average error of 6.00%. The conformation study by FTIR observed that the drying stress increased the secondary structural properties random coil and β-sheet which was compensated by uncoiling of α-helix and transformation of β-turn into β-sheet. The morphology study found that initially β-Lg droplet showed flexible nature but formed firm skin with increasing drying time.

Title: Multiphase heat mass transfer analysis for intermittent drying

Several schemes of energy minimization of drying process including intermittent drying have been attempted. Intermittent drying is conducted by applying different heat inputs in each drying period. An effective and physically meaningful drying model is useful for process design and product technology. The lumped reaction engineering approach (L-REA) has been shown previously to be accurate to model the intermittent drying In L-REA, the REA (reaction engineering approach) is used to describe the global drying rate. In this study, the REA is used to model the local evaporation/condensation rate and combined with the mechanistic drying models to yield the spatial reaction engineering approach (S-REA), a non-equilibrium multiphase drying model. The accuracy of the S-REA to model the intermittent drying under time-varying drying air temperature is evaluated here. In order to incorporate the effect of time-varying drying air temperature, the equilibrium activation energy and boundary condition of heat balance implement the corresponding drying settings in each drying period. The results of modeling using the S-REA match well with the experimental data. The S-REA can yield the spatial profiles of moisture content, concentration of water vapor, temperature and local evaporation/condensation rate so that better understanding of transport phenomena of intermittent drying can be obtained. It is argued here that the REA can describe the local evaporation rate under time-varying external conditions well. The S-REA is an effective non-equilibrium multiphase approach for modeling of intermittent drying process.

Title: Self-heating of combustible materials during heat-mass transfer processes

During composting, self-heating may occur due to the exothermicities of the chemical and biological reactions. An accurate model for predicting maximum temperature is useful in predicting whether the phenomena would occur and to what extent it would have undergone. Elevated temperatures would lead to undesirable situations such as the release of large amount of toxic gases or sometimes would even lead to spontaneous combustion. In this paper, we report a new model for predicting the profiles of temperature, concentration of oxygen, moisture content and concentration of water vapor during composting. The model, which consists of a set of equations of conservation of heat and mass transfer as well as biological heating term, employs the reaction engineering approach (REA) framework to describe the local evaporation/condensation rate quantitatively. A good agreement between the predicted and experimental data of temperature during composting of sewage sludge is observed. The modeling indicates that the maximum temperature is achieved after some 46 weeks of composting. Following this period, the temperature decreases in line with a significant decrease in moisture content and a tremendous increase in concentration of water vapor, indicating the massive cooling effect due to water evaporation. The spatial profiles indicate that the maximum temperature is approximately located at the middle-bottom of the compost piles. Towards the upper surface of the piles, the moisture content and concentration of water vapor decreases due to the moisture transfer to the surrounding. The newly proposed model can be used as reliable simulation tool to explore several geometry configurations and operating conditions for avoiding elevated temperature build-up and self-heating during industrial composting.

Education

Units taught

ENG1060 - Computing for Engineers

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International grants

  • Innovative drying process for high quality food products, Aditya Putranto, 2017-2019, Royal Society UK
  • Modeling of multiphase heat mass transfer process using reaction engineering approachAditya Putranto, Aug 2017 - 2018, Queen's University Belfast
  • Production of biomass-based adsorbents for removal of contaminantsAditya Putranto, 2014-2016, International Toray Science and Foundation

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International Award/Recognition/Exhibition/Stewardship

  • Outstanding Drying Book Award, Asia Pacific Drying Conference 2017
  • Young Drying Scientist, Asia Pacific Drying Conference 2015
  • The Hottest Paper for paper published in AIChE Journal, WIley
  • The Best Paper, International Conference on Food Properties 2014
  • Paper made as keynote speech, International Drying Symposium 2014
  • Paper made as keynote speech, Asia Pacific Drying Conference 2017
  • Associate Editor, International Journal of Food Engineering, 2013 - now