Research
Dr. Moreno’s lab at Missouri State University explores techniques for the capture and storage of energy. The research encompasses primarily concepts from an engineering perspective, but also welcomes perspectives from related science fields. Dr. Moreno has worked with engineering students in the cooperative engineering program between Missouri State and Missouri S&T, as well as undergraduate and graduate students from the Physics, Astronomy, and Materials Science (PAMS) department at MSU. Below are some of the research projects that Dr. Moreno and his research students have either worked on or plan to work on:
As the world progresses toward renewable energy sources, such as solar, the energy harnessed will need to be stored effectively when it is not always naturally available. This can be especially useful in desert climates with large daily temperature swings [1,2]. However, while heat cannot be easily converted, it can be stored and effectively distributed to provide heating in commercial or residential spaces where needed. A lab-scale test stand has been developed to evaluate the capabilities of liquid water for thermal energy storage (i.e. through sources such as solar), its long-term storage, and ultimately, its use for commercial applications in heating.
Thermal Energy Storage/Conversion: (Heat Transfer)
Thermal energy storage/dissipation:
Preliminary experiments have evaluated the retention of heat and mass in a liquid water beaker using the three main modes of heat transfer (Fig. 1): conduction, convection, and radiation [3]. The purpose of the experiments was to determine the effect of heating mode on the ability to retain heated water during cooling, and the ramifications of each when operating energy storage systems. Initially, the project was developed for outreach and educational purposes, connecting relevant heat transfer concepts with real-world applications. Insulation will be added to the system to better retain the captured heat, and the water will be circulated at various pumping speeds to evaluate the system’s ability to transport the liquid water once stored.
The project is now being further developed to examine the ability to store and dissipate energy through an expandable container (Fig. 2). Here, the liquid/vapor phase change of water will be leveraged alongside the container's increased surface area to increase the rate of heat dissipation to the environment. This study incorporates more advanced two-phase heat transfer concepts with future design modifications (i.e. finned surfaces) that can enhance the heat dissipation within the expandable container. This has applications in thermal management for battery systems, where the liquid/vapor transition contains much more latent energy than traditional solid/liquid and the volume expansion can be used for further heat dissipation (Fig. 3).
Fig. 1. Configuration of experimental setup with different heat transfer modes, (A) Conduction Experimental Setup, 80°C, 120°C, and 150°C Set Points, (B) Convection Experimental Setup 15W – 30W DC Power Used, (C) Radiation Experimental Setup Lamp Distances Varied
Fig. 2. Demonstration of setup with two-phase heat transfer in an expandable container.
Fig. 3. Final Chamber Setup for liquid-vapor piston.
Heat exchanger design for indoor thermal management:
Beyond the capture/retention of thermal energy, the transport and distribution of this energy is crucial. An application of TES is in residences and other high-occupancy buildings, where daily temperature fluctuations enable capture of heat in warmer times of day and then later release to provide warmth during colder times. Heat exchangers can be used in TES systems [4], with many examples focusing on optimizing heat exchanger design. Heat exchangers that mix preheated water with air (Fig. 4) can serve as a simpler, more useful means of thermal energy transfer without requiring additional chemicals or materials.
This study focused on a heat exchanger modification for a concentric double-pipe configuration. Enhancements to the heat exchanger design can also be made to examine improvements in the heat exchanger’s performance. Both modifications of the fins and spring coils (Fig. 5) are expected to improve heat transfer rates performance due to the added surface contact and enhanced fluid motion. The modifications are applied directly to the inner pipe of the heat exchanger – the outer surface includes fins to increase the contact area between the two fluids, while the inner surface includes spring-like coils to enhance mixing and subsequent heat transfer further. This heat exchanger (Fig. 6) has been built and developed previously, with preliminary results indicating improved performance when the finned design is used, but not with the finned/spring configuration under the lower flow rates tested [5].
Presently, the heat exchanger is now being modified to provide additional power to vaporize the liquid water. This will enable studies for two-phase flow as vapor condenses to liquid upon heating the air, and effects of the vapor-liquid condensation under different geometric configurations in the heat exchanger.
Fig. 4. Depiction of heat exchanger facility as built in the lab.
Fig. 5. Inner pipe configurations for heat exchanger designs developed. (A) Straight pipe, (B) Straight pipe with fins, (C) straight pipe with fins and spring.
Fig. 6. Heat exchanger setup for single-phase liquid water flow with air.
Heat transfer – educational research development:
As technology progresses, engineering students must develop competency in computational problem-solving skills to succeed in their future careers [6]. Numerical modeling for complex problems can be applied across multiple courses, but it is also important that fundamentals to understand the equations trends shown are retained. It is challenging to effectively encompass both key theoretical concepts and the more practical numerical modeling in the limited amount of time that can be spent on an undergraduate course [7-8]. Some institutions have implemented advanced software techniques including computational fluid dynamics (CFD) into their curricula [9]. However, there is a wide range of software available for CFD modeling, which can limit the value if only one type of software is focused on.
Previously, our group developed a numerical heat transfer model in MATLAB [10] that focused on laminar flow and successfully integrated with theory. For laminar flow, the correlations relating convective heat transfer to that of pure conduction were well known and confirmed in the model as an initial validation (Fig. 7). Other examples include incorporation of heat generation, through means such as chemical reactions or viscous dissipation, and a more realistic external convective condition to demonstrate the heating or cooling of the pipe when exposed to ambient air or another medium at a single temperature.
Fig. 7. Illustration of grid setup.
The studies have also been expanded to demonstrate flow in parallel and counter flow double pipe heat exchangers (Fig. 8) [11], again enforcing another connection seen in the thermal sciences courses. While the current fundamental study is limited to laminar flow with this simple geometry, it nonetheless serves as a reliable, illustrative tool to bridge the gap between numerical equations, advanced CFD modeling, and expected values in experimental setups.
Fig. 8. Concentric counter flow heat exchanger temperature contour.
Electrochemical Energy Storage/Conversion: (Batteries & Related Technologies):
Li-ion Battery:
While lithium-ion (Li-ion) batteries remain ubiquitous due to their high energy density and high discharge rates, safety and cycling life challenges must be addressed to enable greater system scale-up, such as in electric vehicles [12]. Aging is another challenge in Li-ion batteries for large-scale applications. This aging is largely affected by a multitude of factors, including temperature, size, chemical composition, voltage cutoff, and depth of discharge.
Experimentally, the Moreno Lab is constructing smaller-scale Li-ion batteries in coin cells (Fig. 4) and studying their characteristics to determine long-term performance. Computational models have being developed to predict changes in performance on scale-up, considering equivalent electrical circuits to simulate cycling, and energy balance to account for temperature changes [13]. Electrochemical impedance spectroscopy (EIS) testing can be used to best fit experimental parameters to the model, using equivalent circuits (Fig. 9). Variations in temperature, particularly for colder environments and extraterrestrial applications, are also being tested. Dr. Moreno’s lab employs several refrigerators and freezers of different temperature ranges, which can be used for a wide range of purposes from low-temperature electrochemical studies to relevant class demonstrations in thermodynamics.
Fig. 9. (A) Traditional Li-ion battery circuit. (B) Equivalent circuit to be used for comparison to EIS studies and modeling.
Fig. 10. Refrigerators in Dr. Moreno’s lab.
Ni-Zn Battery:
Fig. 11. Diagram of the experimental setup used to measure the composition of the cell's gassing.
Nickel-zinc batteries have shown to be a promising alternative to lithium-ion batteries, possessing a long cycle life, safer materials, and can maintain a strong discharge current. The Moreno Lab is studying the cycling characteristics of nickel-zinc batteries, and also characterizing the formation of different gaseous products in the system via mass spectroscopy (Fig. 11). This research is being done in collaboration with Aesir Technologies, Inc., situated in Joplin, Missouri. The initial gas evolution-based research has been developed experimentally (Fig. 12) as well as computationally and published in the Journal of Power Sources [14]. The next phase of the project will merge these studies with continued research in Dr. Moreno’s lab on battery studies, with lower temperatures for extraterrestrial applications as well as expansion to a flowable cell to examine influence of different electrolytes, and over a larger area and with varying temperatures.
Fig. 12. (A) Cell voltage and current during 5 cycles at a rate of C/3. (B) Cell voltage and H2/O2 partial pressure during the same test.
Electrochemical CO2 capture/utilization:
CO2 emissions can be decreased via carbon capture and subsequently conversion to a range of value-added fuel products - essentially, the inverse of combustion. Value-added products include carbon monoxide, methanol, formic acid, and hydrogen, among other higher-order carbon products. The exact formation of fuel products can get complicated, and electrochemical methods enable selectivity based on the catalyst used (Fig. 1B). Additionally, traditional CO2 conversion processes employ high temperatures and pressures, reducing cost/manufacturing concerns with an electrochemical process [15]. While operating an electrochemical system for CO2 conversion does not require elevated temperatures or pressures, studies have shown that conditions slightly above ambient can yield more favorable results [16].
Fig. 13. In-house H-cell batch reactor with components labelled.
Fig. 14. (A) Schematic of batch cell. (B) Illustration of process used in dual-cell flow reactor, decoupling reduction and production processes.
Higher pressures can increase the solubility of CO2 in an aqueous solution, provided the system built can handle higher pressures and the increased solubility does not significantly alter the solution pH. While CO2 solubility decreases at higher temperatures, other factors such as the diffusion coefficient and conductivity can enhance performance. The Moreno lab is presently studying the effects of increased temperatures and pressures for electrochemical CO2 conversion, using an in-house H-cell (Fig. 13), and later scaling up to a flowable system for increased fuel production.
The conversion of CO2 to formate with an enzymatic catalyst (Fig. 14) has also been studied extensively via Dr. Moreno’s previous work. Building on that, a more expansive study was developed computationally, exploring a larger number of parameters within the system and over wider ranges (Fig. 15). This work has been published in the Journal of CO2 Utilization [17] and has also been released via Missouri State CNAS Blog: https://blogs.missouristate.edu/cnas-newswatch/2024/07/26/optimizing-electrochemical-conversion-of-co2/
Fig. 15. Dual sweep of charge carrier concentration and applied voltage in the flow cell. (A) Formate production rate, (B) efficiency. Default conditions are CK = 0.1 M, T = 20 °C, and P = 5 bar.
Thermodynamic applications for water desalination:
In thermodynamics, it is well-known that input work is required to maintain a space as hot or cold (refrigeration). Desalination can be thought a mixing or "blue" analog to this, to maintain a purified stream against a natural concentration gradient. The inverse process of mixing high and low concentration water streams to extract "blue" energy may serve as a viable alternative to wind/solar in regions where such salinity gradients are naturally available. This energy from mixing can be thought of as analogous to a heat engine.
Analogous thermodynamic terms can be developed for electrosorption-based cycles to improve cycle efficiency based on different cycle operations. By using cycles under operations analogous to Carnot-like operation in a blue refrigeration (desalination) cycle, theoretical efficiency can be boosted from 9% to almost 35% [18]. Conversely, for the reverse mixing process, several different analogies for different heat cycles (such as Carnot and Stirling) can be developed, showing performance changes based on cycle operation [19].
For real electrodes constructed and tested experimentally (Fig. 16), the thermodynamic limits can be understood by examining the adsorption characteristics of the electrodes (including properties such as enthalpy and entropy). Thermodynamic adsorption isotherms for desalination have been published experimentally [20], but these require many individual experiments varying both concentrations and temperatures. The theory involved in electrochemical adsorption isotherms could be of interest to a diverse range of disciplines. While this has been done previously for traditional CDI (Fig. 17) [21], currently we aim to use flow electrode CDI to investigate its own adsorption limits and the extent to which its adsorption and continued cycling can be optimized.
Fig. 16. Experimental setup for the CDI cell, enabling varying temperatures via heating elements.
Fig. 17. Maximum removal per cycle vs concentration at varying temperatures.
References:
1. Dell RM, Rand DAJ. Energy storage—a key technology for global energy sustainability. Journal of power sources. 2001;100(1-2):2-17.
2. Sarbu I, Sebarchievici C. A comprehensive review of thermal energy storage. Sustainability. 2018;10(1):191.
3. Moreno D, Reeves J, Simpson S, Wijahat A. A Lab-Scale Test Stand for Evaluating Thermal Energy Storage Using Different Modes of Heat Transfer. InASME International Mechanical Engineering Congress and Exposition 2025 Nov 16 (Vol. 89381, p. V007T10A036). American Society of Mechanical Engineers.
4. Agyenim F, Eames P, Smyth M. A comparison of heat transfer enhancement in a medium temperature thermal energy storage heat exchanger using fins. Solar Energy. 2009;83(9):1509-20.
5. Steel D, Moreno D. Optimizing Heat Transfer in a Modular Concentric Tube Heat Exchanger for Renewable Energy Applications. InASME International Mechanical Engineering Congress and Exposition 2025 Nov 16 (Vol. 89398, p. V008T12A010). American Society of Mechanical Engineers.
6. Swart J, editor Theory versus practical in a curriculum for engineering students—A case study. AFRICON 2009; 2009: IEEE.
7. Andriychuk M. Numerical Simulation: From Theory to Industry: BoD–Books on Demand; 2012.
8. Hughes AJ, Merrill C. Solving Concurrent and Nonconcurrent Coplanar Force Systems: Balancing Theory and Practice in the Technology and Engineering Education Classroom. Technology and Engineering Teacher. 2020;80(1):16.
9. Mokhtar W, editor Project-based learning (PBL): an effective tool to teach an undergraduate CFD course. 2011 ASEE Annual Conference & Exposition; 2011.
10. Simpson S, Moreno DA. Development of an enhanced heat transfer model of laminar pipe flow for pedagogical and research purposes. In2024 ASEE Midwest Section Conference 2024 Sep 10.
11. Simpson S, Moreno D. Numerical Pipe Flow Model to Demonstrate Laminar Flow in Concentric Double-Pipe Heat Exchangers. InHeat Transfer Summer Conference 2025 Jul 8 (Vol. 88988, p. V001T11A007). American Society of Mechanical Engineers.
12. Alyakhni A, Boulon L, Vinassa JM, Briat O. A comprehensive review on energy management strategies for electric vehicles considering degradation using aging models. IEEE Access. 2021 Oct 15;9:143922-40.
13. Moreno D, Rapp EB, Shortt J, Drecker M, Ellis R. Integrating Modeling and Experimental Results for Li-Ion Batteries at Cold Temperatures for Experimental Applications. InSMT 2025.
14. Moreno D, Landgraf N, Cornelison D. Evaluation and mitigation of H2 and O2 evolution in Ni-Zn battery. Journal of Power Sources. 2026 Apr 30;672:239663.
15. Moreno D, Omosebi A, Jeon BW, Abad K, Kim YH, Thompson J, Liu K. Electrochemical CO2 conversion to formic acid using engineered enzymatic catalysts in a batch reactor. Journal of CO2 Utilization. 2023 Apr 1;70:102441.
16. Lin R, Guo J, Li X, Patel P, Seifitokaldani A. Electrochemical reactors for CO2 conversion. Catalysts. 2020 Apr 26;10(5):473.
17. Moreno D. Theoretical performance optimization of enzymatic electrochemical CO2 reduction to formate: Voltage, concentration, temperature, pressure, and flow rate. Journal of CO2 Utilization. 2024 May 1;83:102805.
18. Moreno D, Hatzell MC. Constant chemical potential cycles for capacitive deionization. Physical Chemistry Chemical Physics. 2019;21(44):24512-7.
19. Moreno D, Hatzell MC. Using Thermodynamics Principles to Optimize Performance of Capacitive Mixing Cycles for Salinity Gradient Energy Generation. InASME Power Conference 2019 Jul 15 (Vol. 59100, p. V001T12A007). American Society of Mechanical Engineers.
20. Mossad M, Zou L. Evaluation of the salt removal efficiency of capacitive deionisation: Kinetics, isotherms and thermodynamics. Chemical engineering journal. 2013 May 1;223:704-13.
21. Moreno D, Nelson H, Cary G, Parker D, Skaggs P. Thermodynamic Evaluation of Electrode Storage for Capacitive Deionization. ACS omega. 2025 Mar 4;10(10):10139-51.