Engineering topics

Cath, Tzahi

Publications and source records attributed to Cath, Tzahi.

7 records

DOE OSTI2024

Energy Where it Matters: Delivering Heat to the Membrane/Water Interface for Enhanced Thermal Desalination

The overall goal of the project is the development of a solar-driven membrane distillation (MD) process that can treat high salinity brines (>100 g/L) at a cost below $1.5/m3. The process relies on thermally and electrically conducting MD membranes that deliver solar heat directly to the membrane surface and prevent membrane fouling through the application of electrical potentials to the membrane surface.

14 SOLAR ENERGY↗

DOE OSTI2022

Black-box optimization of a closed-circuit reverse osmosis system for desalination through extremum seeking control

We study the minimization of the cost function of a closed-circuit desalination reverse osmosis (CCRO) system, which is used for producing drinking water. The cost function is a trade-off between the specific energy consumption and the specific brine management cost. The extremum-seeking controller (ESC) manipulates the critical electric conductivity of the brine to minimize the cost function. Experiments were designed in which the composition of the feed salinity is increased to test the controller’s ability to converge to a new optimum. The ESC was able to shift the critical conductivity to a new optimum, which resulted in a 9% improvement in the cost function.

Chowdhury, Dhruba↗

DOE OSTI2021

National Alliance for Water Innovation (NAWI) Master Technology Roadmap

The National Alliance for Water Innovation (NAWI) is a research consortium formed to accelerate transformative research in desalination and treatment to lower the cost and energy required to produce clean water from nontraditional water sources and realize a circular water economy. Prior to developing this master roadmap, a team of NAWI researchers and water professionals engaged in a detailed process of evaluating water uses, state-of-the-art technologies, emerging technologies and existing uses of desalination and advanced water technologies within five major water user categories in the United States. The resulting Water User Sector Roadmaps were complemented by a Baseline Analysis of a suite of representative treatment systems conducted by NAWI researchers working in collaboration with the hub’s Industrial Partners. This Master Roadmap, which synthesizes the findings from these different efforts as well as feedback from members of NAWI’s Research Advisory Council, serves as the basis for identifying NAWI’s research Areas of Interest (AOIs).

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2020

Mineral Scale Prevention on Electrically Conducting Membrane Distillation Membranes Using Induced Electrophoretic Mixing

The growth of mineral crystals on surfaces is a challenge across multiple industrial processes. Membrane-based desalination processes, in particular, are plagued by crystal growth (known as scaling), which restricts the flow of water through the membrane, can cause membrane wetting in membrane distillation, and can lead to the physical destruction of the membrane material. Scaling occurs when supersaturated conditions develop along the membrane surface due to the passage of water through the membrane, a process known as concentration polarization. To reduce scaling, concentration polarization is minimized by encouraging turbulent conditions and by reducing the amount of water recovered from the saline feed. In addition, antiscaling chemicals can be used to reduce the availability of cations. Here, we report on an energy-efficient electrophoretic mixing method capable of nearly eliminating CaSO4 and silicate scaling on electrically conducting membrane distillation (ECMD) membranes. The ECMD membrane material is composed of a percolating layer of carbon nanotubes deposited on porous polypropylene support and cross-linked by poly(vinyl alcohol). The application of low alternating potentials (2 Vpp,1Hz) had a dramatic impact on scale formation, with the impact highly dependent on the frequency of the applied signal, and in the case of silicate, on the pH of the solution.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2018

Multi-configuration Membrane Distillation Model (MCMD)

Many membrane distillation models have been created to simulate the heat and mass exchange process involved but most of the literature only validates models to a couple of cases with minor configuration changes. Tools are needed that allow tradeoffs between many configurations. The multiconfiguration membrane distillation model handles many configurations. This report introduces membrane distillation, provides theory, and presents the work to verify and validate the model against experimental data from Colorado School of Mines and a lower resolution model created at the National Renewable Energy Laboratory. Though more data analysis and testing are needed, an initial look at the model to experimental comparisons indicates that the model correlates to the data well but that design comparisons are likely to be incorrect across a broad range of configurations. More accurate quantification of heat and mass transfer through computational fluid mechanics is suggested.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2018

Membrane Specifications for Multi-Configuration Membrane Distillation Model

The data includes the membrane properties and specifications used for multi-configuration membrane distillation desalination. In this study, membranes from CLARCOR, 3M, and Aquastill are tested in counter-current, co-current and air-gap configurations at Colorado School of Mines (CSM), Advanced Water technology Center ( Aqwatech) laboratories. In the data sheets: The "theoretical" worksheet, contains steady-state values of the experimental runs and also provides several calculated values. The "Specifications" worksheet contains the inputs to the experiment. The "Data" spreadsheet contains the entire set of data and the rest of the sheets "20-40", "20-45", ...etc., contain individual portions of the data with variation of feed temperatures.

15 GEOTHERMAL ENERGY↗

DOE OSTI2017

Desalination of Impaired Water Using Geothermal Energy

Membrane distillation (MD) and nanofiltration (NF) are explored as a means to provide high quality water for on-site use at the Tuscarora geothermal power plant in northern Nevada. The plant uses a wet cooling tower, but decreasing flow from the wells providing makeup water necessitates exploration for alternative water or alternative cooling sources. Scenarios are explored to extend cooling water by (1) extracting fresh water from the geothermal brine, (2) upgrading the makeup-water quality to allow for increased cycles of concentration in the cooling tower, or (3) recovering water from the cooling tower blowdown. The preliminary cost analysis indicates that applying NF to extract water from the injection brine is the most attractive option of the scenarios examined. This approach may be useful for other plants as well. The estimated cost for the NF treatment of the injection brine ranges from $0.63/m3 to $0.45/m3 and provides a reduction in the current makeup well flows of 35% to 71%. Savings from the reduction in makeup well pumping and chemical treatment do not fully offset the estimated cost of the proposed treatment systems; the site will have to weigh the cost of these water treatment options versus alternatives in light of the diminishing flows from the existing cooling-water wells. Testing is planned to quantify the performance of the proposed NF and MD technologies and help refine the estimated system costs.

15 GEOTHERMAL ENERGY↗