Mehdi Mortazavi
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​Multiscale Thermal Fluids Laboratory (MTFL)

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ASME Journal of Fuel Cell Science and Technology
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About MTFL
​In MTFL, we focus on thermo-fluids problems over a wide range of applications. Capillary-scale multiphase flow, transport phenomena in porous media, droplet dynamics, and evaluating hydrodynamic and thermal performance of additively manufactured heat exchangers, heat sinks, and flow channels are some of the research topics that we are currently working on. Undergraduate and graduate students are trained and supervised to conduct research activities in this lab.

 

 
Research
Transport phenomena in proton exchange membrane (PEM) fuel cell
Liquid water transport in PEM fuel cell flow channels has been studied in an ex-situ setup. Particularly, liquid water droplet detachment from the surface of the gas diffusion layer (GDL) has been investigated under different gas flow rates and different PTFE content in GDL. Air and hydrogen gases were supplied in flow channel to represent liquid water droplet detachment in cathode and anode of the PEM fuel cell, respectively.

​Click here to read the journal article.
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Capillary-scale water transport through porous media
Water transport through porous media of PEM fuel cell is a capillary-scale transport phenomena that has been investigated. Liquid water breakthrough pressures have been measured for GDLs with different thicknesses and different PTFE contents. Liquid water pressure signature through porous layer has been studied in details.

​Click here to read the journal article.
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In-plane microstructure of PEM fuel cell porous media
SEM images were taken from surface of GDL samples and were analyzed through image processing techniques. Important information such as pore roundness distribution, pore roundness distribution, and mean pore diameter were calculated. The data obtained in this study can be utilized in modeling water transport through the porous structure of GDL. It was observed that the mean pore diameter of Toray carbon paper does not change with its thickness and PTFE content. Mean pore diameter for Toray carbon papers was calculated to be around 26µm, regardless of their thicknesses and PTFE content. Finally, the heterogeneous in-plane PTFE distribution on the GDL surface was observed to have no effect on the mean pore diameter of GDLs.

​Click here to read the journal article.
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Liquid-gas two-phase flow pressure drop in mini/micro-channels
Liquid-gas two-phase flow pressure drop has extensively reviewed prior to designing experimental setup. The literature review focus was on two-phase flow in PEM fuel cell flow channels. However, two-phase flow models for general applications (conventional channels) were also included in this study. Conducting this comprehensive study helped defining shortcomings on models that had been proposed for the application of PEM fuel cell. This study built the foundation for future research on the topic of capillary-scale two-phase flow in mini/micro-channels.

​Click here to read the journal article.

Capillary scale two-phase flow pressure drop in minichannels
Liquid-gas two-phase flow pressure drops in minichannels (2mmx1mm) were measured and compared to various two-phase flow pressure drop models proposed for minichannels. Both the separated flow model and homogenous equilibrium model were evaluated. Results showed that the former outperforms the latter in predicting the two-phase flow pressure drop in PEM fuel cell flow channels. Among the correlations evaluated in the separated flow model,  the model proposed by Mishima and Hibiki demonstrated strongest prediction capability for the flow condition of this study. 

Click here to read the journal article.

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Energy conversion and storage
​In this study, a new finned piston compressor that is characterized by increased heat transfer area and coefficient has been designed, analyzed, manufactured and experimentally tested. Results show that the heat transfer along one cycle has increased in the finned compressor by 32 times compared to a classic piston compressor. In addition, although the volumetric efficiency decreased slightly in the finned compressor (8%), the exergetic efficiency was observed to increase from 55.1% in a classic piston to 78.4% in the finned piston.

Click here to read the journal article.
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Enhanced water removal from PEM fuel cell flow channels
​In this study, an enhanced liquid water removal scheme from an ex-situ PEM fuel cell flow channel is investigated by superimposing acoustic pressure waves on air flow prior to entering into the flow channel. Acoustic pressure waves at different frequencies were superimposed on air flow and water accumulation as well as liquid-gas two-phase flow pressure drop were evaluated during experiments. Acoustic pressure waves in the form of sine functions and at different frequencies between 20 and 120 Hz were superimposed on air flow. The lowest water accumulation within the flow channel was obtained when acoustic pressure waves were superimposed at 80 Hz. This frequency is close to natural frequency of water droplets at the size of droplets formed within the flow channel and therefore, it is speculated that droplets are expelled due to resonance. 
In addition, water removal for three different superimposition schemes were evaluated in this study; (i) continuous superimposition, (ii) pulsating on and off, and (iii) on demand. The on demand superimposition represents superimposing acoustic pressure waves when speaker was generally off and was turned on once a droplet was formed within the flow channel. Comparing speaker energy for different modes indicates that the latter is the most efficient superimposition scheme with respect to energy used in speaker to expel the same amount of water content.


Click here to read the journal article.
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This video shows water removal from the flow channel of the test section. Three separate experiments were conducted to study the effect of superimposing acoustic pressure wave on water removal from the surface of the flow channel. The flow channel on left belongs to an experiment with no acoustic pressure wave being superimposed on air. The middle flow channel is when the acoustic pressure wave is applied with a pulsating mode (the speaker was on for 10 s and was off for 10 s). The flow channel on right belongs to an experiment when the speaker was continuously on. This video shows that superimposing acoustic pressure wave can expel water from the flow channel due to resonance that occurs at frequency close to natural frequency of water droplets (compare water content at the end of the video).

Drainage phase diagram in PEM fuel cell porous layer under compression
​In this study, the drainage phase diagram of the PEM fuel cell porous layer, GDL, was investigated at different compressions. The stable displacement, capillary fingering, and viscous fingering flow regimes were evaluated in carbon paper and carbon cloth samples at four different compressions. While only capillary fingering is the subject of PEM fuel cell, obtaining data for the stable displacement and viscous fingering flow regimes can be beneficial for validating pore network models. In this study, liquid water or air percolation within the plane of the GDL was visualized with a CCD camera while the percolation pressure was measured with a pressure transducer. Images were analyzed to obtain the nondimensional wetted area which was defined as the area occupied by the wetting fluid to the GDL sample area.

​Click here to read the journal article.
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Applications of machine learning in PEM fuel cell two-phase flow
In this study a novel application of machine learning to quantify the liquid water accumulation in PEM fuel cell flow channel is introduced. To correlate liquid water distribution with a two-phase flow pressure drop, this work trains various machine learning models using images of water slugs in a flow channel to predict the pressure drop range. Images of two-phase flow were post-processed and used as input data to three machine learning models: Logistic Regression, Support Vector Machine and Artificial Neural Networks (ANN) to classify the images into three pressure classes: (i) pressure drop less than 15 Pa, (ii) pressure drop between 15 and 30 Pa, and (iii) pressure drop greater than 30 Pa. The performance comparison of machine learning models is reported using the confusion matrices and classification accuracy. ANN performed best for this application and resulted in 95% accuracy on both train and test datasets. This approach can be utilized to predict the pressure drop values in the flow channels of PEM fuel cells based on liquid water content distribution along the channel.

Click here for the journal article.

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Force scaling comparison of two-phase flow in PEM fuel cells compression
In this study, the governing forces on the liquid-gas two-phase flow in PEM fuel cell flow channels are compared analytically. The study compares the magnitude of the forces experienced by liquid water residing in the flow channel. In the analytical model, a 20-cm-long flow channel was analyzed and the forces were compared in the stream-wise direction of the channel. Results indicated the dominance of the surface tension forces over other forces applied in the channel. In fact the surface tension forces were observed to be three orders of magnitude greater than the gravitational effects, the second largest force scale for a droplet diameter of 0.1 mm. However, for larger droplets this difference becomes smaller.

Three undergraduate ME students were involved in this research study. Click here to learn more about this study.
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Two-phase flow pressure drop in PEM fuel cell flow channel bends
In this study, liquid-gas two-phase flow pressure drop across PEM fuel cells flow channel bends was studied. Experimental data were compared to some of the existing models that have been developed to predict the pressure drop across bends for larger channels. Results showed that existing models cannot properly predict the pressure drop in PEM fuel cell bends. A two-phase flow pressure drop model is developed based on the separate flow model. Results demonstrated that the new model can properly predict the pressure drop with a high accuracy.

Click here to learn more about this study.
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Additively manufactured metallic heat exchanger
In this study, the hydrodynamic and thermal performance of additively manufactured heat exchangers were evaluated. Three manifold-microchannel heat exchangers were additively manufactured from stainless steel and tested experimentally. The overall size of the three heat exchangers was identical but their interior designs were slightly different. One of the benefits of AM technology is the integration of different components into one component. This is beneficial in heat exchanger as it eliminates thermal contact resistance in gaps. This study started as a senior design by Riccardo Clemente as a requirement of his BS degree in Mechanical Engineering and resulted in one journal paper and two peer-reviewed conference papers. 

Click here to learn more about this study.
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Gallery
Here are some photos from the experimental setups that I have developed along with some videos.
This video shows a liquid water droplet sitting on the surface of the gas flow channel. Air is supplied in the channel and flows from left to right. Around 5 seconds into the video, acoustic pressure waves are superimposed on core gas flow at a frequency of 20 Hz. Acoustic pressure waves induce inertial forces in the droplet which deform the droplet in a rocking motion pattern. After one complete rocking motion cycle, the droplet detaches from the surface of the channel. The footage is captured by a high-speed camera at Multiscale Thermal Fluids Laboratory at Western New England University, located in Springfield, MA. The video is slowed down for 200x. This research was funded by NSF (CBET 2018150).
This video shows a water droplet sitting on the surface of the gas flow channel when air is supplied in the channel (from left to right) with a superficial velocity of 10.76 m/s. The video shows that the droplet undergoes an oscillatory trend in this condition. No external excitation (such as acoustic pressure waves) is superimposed on the core gas flow. This video is 10X slowed down. This research was funded by NSF (CBET 2018150).
 
​Members (current and former)
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Sungyong Jung (WNE)
Dr. Jung was a visiting scholar who completed his sabbatical at MTFL (at WNE) during AY 2021-22. During his visit, Dr. Jung studied  water percolation within fresh and used GDL samples. The goal of the project was to validate a former scaling model that characterizes this transport phenomena. Dr. Jung also studied droplet dynamics in shearing gas flows. 

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Alexandra Renzetti (WNE)
Alexandra was an undergraduate student who studied water percolation in the plane of the gas diffusion layer when it is exposed to sub-zero conditions. She collaborated with Olivia to design and fabricate a setup that allowed them to visualize water percolation in this condition. In their setup, the porous layer was in contact with a sub-zero cold plate. Liquid water was injected to the porous layer while a CCD camera visualized water percolation and freezing within the layer.

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Taylor Pedley (WNE)
Taylor participated in an undergraduate research project to study liquid-gas two-phase flow pressure drop in minichannels of PEM fuel cells. In that study, a theoretical approach was taken to compare the frictional and accelerational pressure drops in PEM fuel cell flow channels. Her study was documented as an IEEE ITherm conference paper.  Click here to learn more about her project.  In addition, she studied droplet dynamics in shearing gas flow of PEM fuel cell flow channels. She conducted this study for the two conditions of with and without acoustic pressure waves superimposition. Click here and here to learn more about these studies.

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Ian Bennett (WNE)
Ian, an ME undergraduate student, studied surface roughness in additively manufactured flow channels. This was done by measuring the pressure drop at different flow rates as well as acoustically sensing the noise from the gas flow in the channel. The ultimate goal of the project was to use the pressure drop data along with the acoustic signal from the flow channel in a machine learning algorithm to predict the surface roughness based on either of these two parameters. Click here to learn more about Ian's project.

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Colin Murchie (WNE)
Colin was an ME undergraduate student who studied dynamics of water droplet under the influence of the shear force from the core gas flow. Colin collaborated with Cade Watkins on this project and was responsible to visualize the droplet deformation with high speed imaging. The images were then analyzed to obtain the advancing and receding contact angles. In their setup, they also measured the pressure drop across the droplet. 

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 John Young (WNE)
John, an undergraduate ME student, studied water percolation in used GDLs for different flow regimes of capillary fingering, stable displacement, and viscous fingering. In his experimental setup, the GDL sample was sandwiched between two polycarbonate plates and water was injected to the surface of the GDL. A DSLR camera which was mounted on a microscope visualized the percolation of water in the GDL. A pressure transducer also measured the pressure of water in the injection capillary. 

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 Morgan Schrader (WNE)
Morgan was a senior ME student who conducted research on forces applied on a droplet within the flow channel of a PEM fuel cell. In their analytical study, the five forces of surface tension, gravity, pressure drop, inertia, and shear force from the core gas flow were analyzed along the flow channel. Built into this analysis was the gas flow properties which were changing along the channel because of the electrochemical reactions. Their calculations demonstrated that the surface tension effects are the dominant force within the flow channel. Such effects were obtained to be orders of magnitude greater than the gravitational effects, the second largest force scale in the channel. Click here to learn more about Morgan's project. 

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 Michael Doyle (WNE)
Mike studied water transport phenomena in PEM fuel cell flow channels by analyzing the forces applied on water droplet in the flow channel. Mike's project was in collaboration with Elias and Morgan. One of the parameters that they considered in their study was the droplet size. Their study concluded that the surface tension effect is the dominant force in the flow channel. Also, they demonstrated through analytical calculation that for droplets with diameters around 0.1 mm, the inertia effects cannot overcome the surface tension effects even for a cathode stoichiometric ratio as high as 20. Click here to learn more about their study. 

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 Nathan Ferreira (WNE)
Nate characterized surface roughness features in additively manufactured flow channels. His responsibilities included data acquisition of flow rate and pressure drop as well as acoustic emission when air was supplied into the channel. The goal of his project was to obtain those parameters for different air flow rates within the flow channels and calculate the friction factor based on the pressure drop data. Nate graduated in May 2020.

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 Derek Maccini (WNE)
Derek studied air pressure drop through corrugated heat exchangers. He designed and fabricated multiple heat exchangers with different number of pins and measured air pressure drop through them. The corrugated fins were fabricated based on the gear mechanism that he designed and fabricated by 3D printing. Derek completed his degree in May 2020.

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 Riccardo Clemente (WNE)
Riccardo was a member of MTFL for almost two years during his junior and senior years. He completed his BS in Fall 2019. His senior design project was to design, fabricate, and assemble an experimental setup that tests manifold-microchannel heat exchangers. Riccardo's focus was on the air flow loop. Riccardo is currently working on his PhD in Engineering Management in the Department of Industrial Engineering at WNE. Riccardo presented their undergraduate research project in IEEE 2019 ITherm conference in Las Vegas, NV, and their paper was selected as a featured paper in the session in the same conference. Click here to watch his project on youtube. Also, click here to read his ASME paper and here to read his IEEE paper.

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William Yammen (WNE)
William was an undergraduate student in ME and completed his BS in Spring 2019. He  collaborated with Riccardo and Nathan on the additively manufactured manifold-microchannel heat exchanger project. His focus was on data acquisition system that measured and records temperatures and pressures of air and water flows. William presented their undergraduate research project through a poster in IEEE 2019 ITherm conference in Las Vegas, NV. He also received travel grant from IEEE ITherm conference to present their work as a poster. Click here to watch his project on youtube. ​Also, click here to read his ASME paper and here to read his IEEE paper.

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Joseph Connors (WNE)
Joseph was an undergraduate student in ME and graduated in Spring 2019. He collaborated with Cory to study the effects of gas diffusion layer (GDL) compression on water percolation in the plane of the GDL. For this purpose, they designed, fabricated, and assembled the experimental setup. Joseph and Cory co-authored a conference paper for ASME 2020 ICNMM conference. Click here to watch his project on youtube. Also, click here to learn more about Joseph's project.

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Emily Lake (WNE)
Emily is an undergraduate ME student who is doing research on the acoustic pressure wave superimposed (APWS) fuel cell project. Emily has designed an APWS PEM fuel cell for lab testing. Emily's research project is funded by Massachusetts Clean Energy Center.

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Dominic Myren (WNE)
Dominic was a MS student who performed research on droplet dynamics in a shear gas flow. Dominic developed a MATLAB code that could analyze high speed images of water droplet when exposed to a shear gas flow with and without acoustic pressure waves superimposition. 

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Olivia Calnan (WNE)
Olivia was an undergraduate student who studied liquid-gas two-phase flow in porous structure of PEM fuel cells. In  a collaboration with Alexandra, they designed and fabricated a setup that allowed them to visualize liquid water percolation within the plane of the gas diffusion layer samples when they were in contact with a sub-zero cold plate.  The objective of their study was to identify water freezing patterns in gas diffusion layers.

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Sam Draper (WNE)
Sam, an ME undergraduate student, collaborated with Ian to characterize surface roughness in additively manufactured flow channels. For this purpose, they measured the pressure drop in flow channels for different gas flow rates. The flow channels had various cross sectional geometries and were built into the metallic coupons by additive manufactured. Channels had equal cross sectional area but were in different patterns. The coupons were manufactured by Advanced Manufacturing LLC in East Hartford, CT.

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Matthew Whinery (WNE)
Matt was an undergraduate student and collaborated with John Young and Kyle Champlain to study water percolation in used GDLs. Matt was responsible to design a mechanism that ensures a uniform compression across the plane of the GDL. In addition, he was responsible for implementing instrumentation to quantify GDL compression. 

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Rebecca Shannon (WNE)
Rebecca was an undergraduate student and her research was on liquid-gas two-phase flow pressure drop in PEM fuel cell flow channel bends. The pressure drop in cathode and anode flow channel bends were investigated in experiments with air-water and hydrogen-water, respectively. A former model which was developed to predict the two-phase flow pressure drop across the 90˚ bend in large channels was retrofitted for the application of PEM fuel cell flow channel bends. Rebecca was also involved with a project to study water percolation in the porous structure of PEM fuel cells. Click here and here to learn more about Rebecca's projects. 

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Cade Watkins (WNE)
Cade was an undergraduate student and collaborated with Colin to study droplet dynamics under the influence of shear flows when they are superimposed with acoustic pressure waves. Colin designed a transparent test section that allowed him to visualize the droplet from a side-view angle. The experimental setup featured a back light to illuminate the droplet as well as a high speed camera on the opposite side of the test section. Their setup can be described as a "high-speed dynamic goniometer".

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Kyle Champlain (WNE)
Kyle, an ME undergraduate student, collaborated with John Young to study water percolation in the plane of the gas diffusion layer in PEM fuel cells. Kyle was responsible for imaging and analyzing images of water percolation. The study was similar to a recent work which was published by Mortazavi et al. (Journal of Power Sources Advances, 2020) with two exceptions: (1) the percolation of water in used GDLs (rather than new GDLs) was to be investigated, and (2) a smaller field of view was considered. The latter was achieved by imaging the percolation with a microscope.  ​

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John Shahpazian (WNE)
John studied the surface roughness features on additively manufactured flow channels by measuring pressure drop along the channel and obtaining the friction factor at different  air flow rates. John has designed multiple test coupons which were additively manufactured with stainless steel by CCAT (www.ccat.us). John completed his BS in ME in May 2020.

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 Ashley Scott (WNE)
Ashley collaborated with John and Nate to characterize surface roughness features of additively manufactured flow channels. Ashley's focus was on measuring single phase frictional pressure drop along channels with various cross-sectional geometries and at the same hydraulic diameters. The channels were contained in coupons which were additively manufactured from stainless steel and by DMLS method. Ashley completed her degree in May 2020. Click here to learn more about Ashley's project.

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 Elias Rizk (WNE)
Elias studied forces applied on a droplet within the flow channel of a PEM fuel cell. Elias calculated the properties of supplied air along the channel as the electrochemical reactions occur. The two main properties he analyzed were air density and viscosity as the oxygen component was consumed along the channel. Elias collaborated with Morgan Schrader and Mike Doyle on this study. Click here to learn more about their project.

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 Nathan Piascik (WNE)
Nate was a member of MTFL during his junior and senior years in ME program at WNE and graduated in Fall 2019. Nate collaborated with Riccardo and William to fabricate the manifold-microchannel heat exchanger test setup. Nate's responsibility was to complete the chilled water loop to decrease air flow temperature. As a part of his senior design, he tested different copper coil configuration for this purpose. ​Click here to watch his project on youtube. Also, click here to read his ASME paper and here to read his IEEE paper.

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Cory Arden (WNE)
Cory completed his BS in Spring 2019. He studied the effects of gas diffusion layer (GDL) compression on water percolation in the plane of the GDL. For this purpose, he designed, fabricated, and assembled the experimental setup. Cory was also trained on PTFE treating GDL samples. Cory's project is published as a conference paper in the ASME 2020 ICNMM conference (Orlando, FL, summer 2020). Click here to watch his project. Also, click here to learn more about Cory's project.

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Logan LaCroix (WNE)
Logan was an undergraduate student in ME and graduated in Spring 2019. His project was to optimize the fin drop mechanism in baseboard manufacturing process. Logan's project was sponsored by Mestek Inc. Click here to watch his project on youtube.

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Thomas DeMonte (WNE)
Tom completed his undergraduate degree in ME in spring 2018. He collaborated with Brett Sherman on his senior design project. In their project, they designed and fabricated an experimental setup to study water percolation within the porous structure of PEM fuel cells (gas diffusion layer). Their goal was to identify the effect of porous layer compression on water percolation in the plane of the GDL. Click here to watch his project.

Other WNE Alumni​
  • Brett Sherman - B.S. Mechanical Engineering, 2018
  • Abdulrahman Alfaifi - B.S. Mechanical Engineering, 2018
  • Abdulmajeed Aziz - B.S. Mechanical Engineering, 2018
  • Luke Gonyea - B.S. Mechanical Engineering, 2018
  • Thomas Kozak - B.S. Mechanical Engineering, 2018
  • Edward Nemchinsky - B.S. Mechanical Engineering, 2018
  • Mohammad Salem - B.S. Mechanical Engineering, 2018
  • Maxwell Holz - B.S. Mechanical Engineering, 2017
  • Ian Fay - M.S. Mechanical Engineering, 2017
  • Mathew Basile - B.S. Mechanical Engineering, 2017
  • Kyle Barrett - B.S. Mechanical Engineering, 2017
  • Max Magid - B.S. Mechanical Engineering, 2017
  • Luke Allison - B.S. Mechanical Engineering, 2017
  • Alan Hess - B.S. Mechanical Engineering, 2017
  • Nicholas Walp - B.S. Mechanical Engineering, 2017
  • Yuriy Belyy - B.S. Mechanical Engineering, 2017

 
Opening
We always look for strongly motivated students who are interested in conducting research in the area of multiphase flow, capillary-scale transport phenomena,  and heat transfer. Applicants are encouraged to contact Mehdi Mortazavi (mmortazavi@wpi.edu) for further information.
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