Sustainable Thermal Systems Laboratory (STSL)

This is an unusual, personal post.?I pay tribute to my friend Reinhard Radermacher, to celebrate his life and legacy.?So vast was his reach in the professional community that many will write similar messages.?I had known of Reinhard since my student days in the 1980s, and started interacting with him in the early 1990s as I was aspiring to join academe.?As a young researcher, I was always eager to attend his presentations on sorption heat pumps.?Along with Felix Ziegler, he was a student of the father of sorption heat pumps, Georg Alefeld, at Technical University of Munich.?Over the decades, we developed a friendship, and have been part of a small fraternity of about a dozen researchers from the US, Germany, China, Japan, Korea, Spain, Italy, France, the UK and other countries interested in furthering the science and application of sorption heat pumps.?Informal moments exchanged in the hallways and at lunches and at conferences (and the interminable ASHRAE Absorption Technical Committee meetings) are my most treasured memories with Reinhard.?He was always attentive, always “on.”?A mere mention of an idea I was kicking around would make him recognize its importance or otherwise, and he would engage in a lucid discussion and share with me all he knew about related developments from decades ago.?His book on absorption cycles was the veritable atlas of every conceivable cycle for heat pumping.?He always encouraged the ideas of anyone he encountered with genuine enthusiasm.?In the larger HVAC&R community, it is difficult to imagine anyone who has not come across his contributions.?He was a constant fixture at ASHRAE and International Institute of Refrigeration meetings, spearheading initiatives at both entities, including as Editor of the ASHRAE Research journal.?I was proud to have been invited by him to serve as associate editor, and in 2005, we also jointly hosted the International Sorption Heat Pump conference.?I could very well have been his colleague, when I received an offer to join the University of Maryland in 2002, but fate brought me here.?As founder and director of the Center for Environmental Energy Engineering , he impacted the lives of many students and colleagues, and was one of the true exponents of translating scientific insights into practical systems through his connections with industry.?Many of his students have become leaders in the field.?In fact, he interacted with many of my students and even my son Vivek Garimella just two weeks ago at the Gordon Research Conferences in Pomona, CA, conveying with that characteristic enthusiasm the importance our work to them!?A giving person throughout his career, he leaves behind an unmatched legacy.?It is hard to think of him in the past tense, but his contributions will live on for decades to come, through the students and colleagues he inspired.?My sincere condolences to his family and to the larger community of friends he leaves behind.?Farewell, Reinhard! #heatpump, #absorption, #HVAC

Prof. Srinivas Garimella is the Hightower Chair in Engineering and Director of the Sustainable Thermal Systems Laboratory at Georgia Institute of Technology. He has held prior positions as Research Scientist at Battelle Memorial Institute, Senior Engineer at General Motors Corp., and Associate Professor at Western Michigan University and Iowa State University. He conducts research in the areas of microscale phase change heat and mass transfer, vapor compression and sorption heat pumps, and heat recovery, upgrade and storage. He is a Fellow of the ASME and of ASHRAE. He is Editor of the Int. J. Air-conditioning and Refrigeration, and past Associate Editor of the ASME J. Heat Transfer and ASME J Energy Resources Technology, and of the ASHRAE SBTE Journal. He is Past Chair of the Advanced Energy Systems Division of ASME and was on the ASHRAE Research Administration Committee. He held the William and Virginia Binger Associate Professorship of Mechanical Engineering at ISU.

The Sustainable Thermal Systems Laboratory (STSL) family was out in full force at the Gordon Research Seminar (GRS) and Gordon Research Conference (GRC) on Micro and Nanoscale Phase Change Phenomena in Pomona, CA.?From left to right, PhD student Raj Agarwal gave a talk and presented a poster on ‘A Novel Two-Phase Flow Regime Identification Model using Pressure-Drop and Acoustic Measurements,’ and will co-chair the next GRS in 2027.?Alumna Allison Mahvi, now Assistant Professor at the University of Wisconsin-Madison, and alumnus Brian Fronk, now Associate Professor at Penn State University, gave talks on ‘Wave Characteristics and Dryout Behavior in Thin Annular Refrigerant Films’ and ‘Mixtures and Natural Working Fluids: Thermal Transport Challenges of Low GWP and PFAS Free Candidates,’ respectively.?Alumnus Matthew Hughes, now a research scientist at Massachusetts Institute of Technology, gave a talk on ‘The Art and Science of Tuning Multiphase Flow and Heat Transfer with Low and High-Frequency Sound.’?Alumnus Bachir El Fil, now back at Georgia Institute of Technology as Assistant Professor, presented a poster on ‘Hydrogel-based high energy density thermal energy storage.’?Vivek Garimella, now a PhD student at University of Illinois Urbana-Champaign, co-chaired the GRS and presented a poster on ‘Analysis of Microscale Phenomena of Electrostatic Oil-Refrigerant Separation.’?Sarah Chen, past undergraduate research assistant at STSL and now PhD student at University of California, Berkeley, presented a poster on ‘Low cost evaporative cooling enhancement via heat and mass transfer optimization in a perforated reflective foil and airgap configuration.’?It is a pleasure to be associated with such bright young scientists and research leaders.

Congratulations to Ryan Giometti! We are pleased to announce the successful completion of the requirements of a Master’s degree in Mechanical Engineering by Ryan. He joined STSL in Spring 2023 after receiving a BS in Mechanical Engineering from Georgia Institute of Technology. For his Master’s, Ryan worked on the design of compact condensers enabled by additive manufacturing. He developed a genetic algorithm to optimize the size, number, and spacing of tubes throughout a condenser to adapt to the changing heat transfer coefficient and pressure drop during condensation, which yielded a condenser ~75% smaller than one manufactured using conventional methods under the same operating conditions. Thank you to West Coast Solutions and ELEMENTUM 3D for partnering on this project and to the Office of Naval Research for partial funding of this effort. Ryan now heads to Astranis Space Technologies in San Francisco to design and test thermal systems for the world’s most advanced high-orbit satellites. We wish him the best of luck on this journey. #Congratulations #Masters #STSL George W. Woodruff School of Mechanical Engineering

It was fun to present our progress on our project with my colleague Dr. Akanksha Menon, Ph.D., “Design and Integration of Thermochemical Energy Storage (TCES) into Buildings for Load Shedding/Shifting,” at the U.S. Department of Energy (DOE) Building Technologies Office Peer Review?in Arlington, Virginia, Oct 21-24, 2024.?Our poster was well received, leading to discussions with a variety of stake holders.?A special bonus was to be presenting our progress along with Sustainable Thermal Systems Laboratory (STSL) alumni, Dr. Allison Mahvi?at the University of Wisconsin-Madison, and Dr. Bachir El Fil?who recently joined our faculty at Georgia Institute of Technology, both of whom were presenting their own project updates.?Yet another source of pride was to see that Dr. Alex Rattner, another alumnus from Sustainable Thermal Systems Laboratory (STSL), now on the faculty at Penn State University, was one of the reviewers at this peer review program.?As an educator, there is no better joy than to see your own students as your colleagues and also as your evaluators! #PeerReview #ThermoChemicalEnergyStorage #HeatPump #LoadShifting #Decarbonization

Our paper, “Enhancement of air-side heat transfer in crossflow heat exchangers using auto-fluttering reeds,” recently appeared in the Applied Thermal Engineering Journal. This study investigates the use of autofluttering reeds for the enhancement of air-side heat transfer.?Heat transfer experiments were conducted on an air-cooled heat exchanger representative of those used in the process, HVAC and power plant industries equipped with a set of 1440 rectangular Mylar reeds installed in the air-side channels. Nusselt number and friction factor were measured for flow rates corresponding to air-side Reynolds numbers from 1200< Re < 3400. Heat transfer enhancement up to 60% was observed with a maximum friction factor penalty of 200%. Geometric optimization of the reeds and fin channels could yield additional heat transfer enhancement. This technique offers the possibility of decreasing the size of air-coupled heat exchangers used in a variety of industries. Read more in detail below. #heattransfer #air #enhancement Roland Crystal Srinivas Garimella George W. Woodruff School of Mechanical Engineering. https://lnkd.in/etu-2RUn

Our paper, “Investigation of a novel combined ab- and ad- sorption based thermal energy storage and upgrade system,” recently appeared in the Applied Thermal Engineering Journal. We have designed a sorption-based cycle that combines energy storage and energy upgrade for the purpose of long-term, low-grade heat storage.?A transient model that simulates the charging, storage, and discharge phases was developed to model the underlying ab- and ad- sorption processes. In the representative application under consideration, this cycle couples absorption and adsorption to store this low-grade heat and discharge it at a temperature of 62°C. Discharge temperatures achieved in this work for such long-term energy storage are much higher than those reported in the literature using other storage systems. Long-term energy storage is a key component to decarbonization of building heating, and this cycle demonstrates energy storage densities from 71 to 185 kJ kg-1, depending on the operating conditions under consideration. Read more in detail below. #adsorption #absorption #energystorage Allannah Duffy Srinivas Garimella George W. Woodruff School of Mechanical Engineering https://lnkd.in/e_YKZpkD

Our paper, ‘Modeling steam generation in the free-falling zone in direct-chill casting of aluminum’, is now published in Applied Thermal Engineering! We have developed two coupled models, one of which simulates the solidification and cooling of a representative aluminum 28.8 ton ingot, modeling the transient conduction, aluminum solidification, and water evaporation from the cooling water to predict steam generation. The second model uses the results from the ingot model to describe an entire casting plant as it operates throughout the day. Annual water losses due to evaporation in aluminum casting plants are thereby quantified and validated using actual plant data. The findings show that over 1.5 billion kilograms of water could be saved every year by reclaiming steam from the process, pointing out avenues for significant improvements in energy and water conservation in such casting plants across the world. Read more in detail below! Thank you to Novelis for collaborating on this project with us. #HeatTransfer #Aluminum #WaterRecovery Jacob Tjards Srinivas Garimella George W. Woodruff School of Mechanical Engineering https://lnkd.in/gYGMmVSN

STSL PhD student Jacob Tjards and STSL alumnus Dr. Matthew Hughes attended the 18TH UK Heat Transfer Conference, (https://lnkd.in/gdZycF8c), September 9th – 11th at the University of Birmingham, UK. This conference, which is held every two years under the UK National Heat Transfer Committee, is a key platform for the local and international heat transfer community to convene, share ongoing research, and discuss the latest advancements in the field. Jacob Tjards’ presentation, “Radio Frequency Calcination of Gypsum for Sustainable Wallboard Production”, co-authored by Kristian Lockyear and Dr. Srinivas Garimella, presented experimental results and a model of electromagnetic heating of gypsum for the production of wallboard. The results were used to predict the reduction of energy consumption and emissions by replacing conventional gas-fired ovens with electromagnetic heating driven by electricity. This volumetric heating results in uniform calcination and particle size distribution, significant energy savings, and water savings in the subsequent processing.?Matthew Hughes delivered a presentation entitled "The Broad Reach of Heat Pumps to Decarbonize Numerous End Uses," co-authored by Dr. Srinivas Garimella. Both presentations were well-received by the audience. #Congratulations #UKHTC2024 #HeatTransfer #EMHeating #HeatPumps #STSL