A compact photovoltaic–thermal (PV/T) desalination system: Device development and performance optimization

Globally, about 10% of the world population does not have access to enough fresh water. In many hot-and-dry coastal regions and islands, the desalination of seawater might be the only practical option to have a fresh water supply. Therefore, low-cost desalination system is critical for freshwater demands. To address this issue, a desalination system consisting of solar photovoltaic (PV) and mechanical vapor compression subsystem is proposed in this study. The entire desalination system was modeled and designed to produce 10,000 m3 of fresh water per day at the coast of San Francisco, California. Key components such as water vapor compressor, solar PV panel, and three-stream heat recovery unit were designed, and their performances were analyzed. The effects of design variables and operating conditions on the system performance were investigated through a parametric study. Finally, an economic analysis was conducted and compared with current desalination technologies. The analysis results show that the specific power consumption of desalination system can reach 14.4 kWh/m3 when the evaporation temperature is 70°C. It is found that the evaporating temperature has a great influence on the heat pump system efficiency and evaporator design. The levelized cost of the proposed system is $0.76 per m3 of fresh water which is lower than current grid-powered vapor compression desalination system and other thermal desalination systems. The proposed solar PV driven desalination improves thermoeconomics of desalination system by applying low-lift operating condition to the vapor compression cycle so that it can contribute to solving the fresh water supply challenges.

An approach towards building robust neural networks models using multilayer perceptron through experimentation on different photovoltaic thermal systems

The development of a small-sized nuclear heat-only plant with maximized safety features dedicated to seawater thermal desalination was proposed to address both a serious water crisis and nuclear safety issues, which continue to be perennial problems. In this study, the feasibility of a dedicated nuclear heat-only desalination system for a target country was evaluated in comparison with a target nuclear thermal desalination system. First, the target country was selected, and its current energy and desalination status was investigated. The suitable nuclear desalination options for the target country were then selected. Finally, using corresponding analysis tools, performance and economic analyses were conducted for a dedicated nuclear heat-only desalination system and the target nuclear thermal desalination system. The results of the analyses indicate that operating the small-sized nuclear heat-only plant at low pressures coupled with a seawater thermal desalination plant will considerably improve both the safety and economy without a significant loss in desalination performance. In conclusion, the proposed dedicated nuclear heat-only desalination system is expected to have high potential for solving both problems.

Seawater desalination provides an effective means to address water scarcity intensified by global warming and rising demand. When powered by solar energy, it can supply freshwater with minimal CO 2 emissions. This study develops and compares two fully solar-powered desalination systems, using modeling and simulations, aimed at increasing the Recovery Ratio (RR) and valorizing brine from a Reverse Osmosis (RO) unit. Both systems integrate thermal and electrical energy storage and incorporate Membrane Distillation (MD) units operating in series with RO. System A uses photovoltaic (PV) panels and solar thermal (ST) collectors, while System B combines hybrid photovoltaic/thermal (PV/T) panels with ST collectors. Simulations are performed under real meteorological conditions over one year in Almería, Spain. No previous work has assessed the techno-economic performance of solar-powered hybrid desalination systems with energy storage for higher RRs, nor compared traditional and hybrid solar collectors through dynamic annual simulations. The RO–MD configuration enhances RR and freshwater production relative to RO alone. System A increases output by 9.22%, and System B by 8.60%. RR rises from 40.50% to 44.23% in System A and from 42.04% to 45.66% in System B. PV/T integration in System B further improves performance by preheating seawater, reducing specific energy consumption (SEC), and increasing PV efficiency. This results in an 8.93% production gain and a 3.24% RR increase over System A. Levelized Cost of Water (LCOW) values are 5.01 and 5.27 USD/m 3 for Systems B and A, respectively, higher than conventional water costs but lower than many reported for solar-powered desalination systems. • Placing MD plants in series with a RO unit enhances overall freshwater production and increases the RR. • The solar‑powered RO‑MD system with energy storage achieves a lower LCOW than other solar‑powered desalination options. • A hybrid PV/T collector in an RO‑MD system enables higher freshwater output than a standard PV collector. • A hybrid PV/T collector in an RO‑MD system yields a lower LCOW than a conventional photovoltaic collector.

Introducing a hybrid renewable energy system for production of power and fresh water using parabolic trough solar collectors and LNG cold energy recovery

Technoeconomic analysis of solar thermal desalination

The effects of dispatch strategy on electrical performance of amorphous silicon-based solar photovoltaic-thermal systems

Utilization of nanotechnologies in condensation has been recognized as one opportunity to improve the efficiency of large-scale thermal power and desalination systems. High-performance and stable dropwise condensation in widely-used copper heat exchangers is appealing for energy and water industries. In this work, a scalable and low-cost nanofabrication approach was developed to fabricate superhydrophobic copper oxide (CuO) nanoneedle surfaces to promote dropwise condensation and even jumping-droplet condensation. By conducting systematic surface characterization and in situ environmental scanning electron microscope (ESEM) condensation experiments, we were able to probe the microscopic formation physics of droplets on irregular nanostructured surfaces. At the early stages of condensation process, the interfacial surface tensions at the edge of CuO nanoneedles were found to influence both the local energy barriers for microdroplet growth and the advancing contact angles when droplets undergo depinning. Local surface roughness also has a significant impact on the volume of the condensate within the nanostructures and overall heat transfer from the vapor to substrate. Both our theoretical analysis and in situ ESEM experiments have revealed that the liquid condensate within the nanostructures determines the amount of the work of adhesion and kinetic energy associated with droplet coalescence and jumping. Local and global droplet growth models were also proposed to predict how the microdroplet morphology within nanostructures affects the heat transfer performance of early-stage condensation. Our quantitative analysis of microdroplet formation and growth within irregular nanostructures provides the insight to guide the anodization-based nanofabrication for enhancing dropwise and jumping-droplet condensation performance.

The key step for using nanoparticles for heat transfer applications is to prepare nanofluids, either through the one-step or two-step method. Among applications of nanofluids in heat transfer are to use them as working fluid for hybrid photovoltaic thermal (PV/T) systems. PV/T systems combine photovoltaic modules and solar thermal collectors to produce hot water and electricity simultaneously. This chapter presents classifications of PV/T systems, principles, and performance. Moreover, detailed introduction to nano-material is used for PV/T systems and related parameters such as volume fraction (%) and mass flow rate. Furthermore, the chapter provides a case study of three different PV/T systems which are nanofluid and nano-phase change material (nano-PCM)-based PV/T, a water-based PV/T with a PCM tank, and water-based PV/T with water tank. The findings show an overall improvement in thermo-physical properties as nanoparticles are added to base fluid (water) and phase change material (PCM). Moreover, the highest performance is attributed to the nanofluid and nano-PCM-based PV/T system.

Development and applications of photovoltaic–thermal systems: A review

Solar energy is a renewable energy that can produce heat via a thermal system and generate electricity via a photovoltaic (PV) module. A photovoltaic-thermal (PVT) collector is a system that has a PV module combined with a thermal collector system. The PVT collector is a popular technology for harvesting solar energy. A PVT collector can generate both electrical and thermal energies simultaneously. The study aims to validate the PV and outlet temperature for various mass flow rates and solar radiation. To develop a predictive model, a steady-state energy analysis of a PVT air collector was performed. An energy balance equation was solved using the matrix inversion method. The theoretical model was developed and validated against the experimental results, which have a similar trend and are consistent with the experimental results. On the other hand, the validated model was used to study the performances of PVT air collectors using exergy analysis for the mass flow rate ranging from 0.007 kg/s to 0.07 kg/s and solar radiation ranging from 385 W/m2 to 820 W/m2. The result from the mathematical model was found to be consistent with the experimental data with an accuracy of about 95 %. The average PVT exergy efficiency was found to be 12.7 % and 12.0 % for the theoretical and experimental studies, respectively.

High-performance desalination systems from natural luffa vine: A simple, efficient and environmentally friendly solution for bio-based solar evaporators

Development of a two-fluid model for predicting phase-changing flows inside thermal vapor compressors used in thermal desalination systems

Livestock farms are a major contributor to CO2 emissions. The use of renewable energy sources (RES) is an important step to mitigate emissions from farms. This paper develops and evaluates a market-integrated, cost-effective, and case-sensitive RES solution for livestock farms. For this purpose, the dairy farm at LVAT-ATB in Germany; which includes three barns for milk production with a total area of 3950 m2, was considered. A solar PVT system is designed to most effectively use the heat recovery of the milk coolers and to use the thermal heat from the PVT system to lift the inlet temperature of an electric boiler (E-boiler) and reduce grid electricity consumption. The performance and monthly thermal output of the designed PVT system are evaluated using two different PVT collectors; Solarus (concentrated) and Dual Sun (flat plate). A preliminary analysis was performed to determine the PVT collector most suitable for the livestock farm here studied. The DualSun collector generated a higher electricity output than the Solarus C-PVT, however, the C-PVT was able to reach higher temperatures. Since the LVAT-ATB farm site included an existing heat recovery system, the integration point was carefully defined and a semi-automated system was incorporated to (1) use the heat from the heat recovery system as the inlet heat for the PVT system and (2), to use the PVT buffer tank as additional storage to store excess heat from the heat recovery system. Using this approach, a maximum amount of thermal energy can be stored. The PVT system would further raise the temperature from the heat recovery system and thus minimize the electricity consumption of the E-boiler. Furthermore, a draft layout of all the components and outdoor enclosure was presented. 24 Solarus PVT collectors running at mean temperature of 45 °C meet 16% of the annual hot water demand of the dairy farm by direct solar heat and this number of PVTs can supply up to 38% of hot water demand in summer months. The payback period for this system is less than 6 years and annual electrical energy utilization ratio and highest solar thermal fraction are 9.7 and 51.9%, respectively. Furthermore, 24 PVTs on an annual basis, generate slightly more than 4,200 kWh of electricity that can be used to offset electricity consumed by electric boilers in the LVAT farm.

Experimental and numerical investigation of a novel photovoltaic thermal (PV/T) collector with the energy and exergy analysis