Showing papers by "Shankar Narayanan published in 2017"
TL;DR: The design and demonstration of a device based on a porous metal-organic framework that captures water from the atmosphere at ambient conditions by using low-grade heat from natural sunlight at a flux of less than 1 sun (1 kilowatt per square meter).
Abstract: Atmospheric water is a resource equivalent to ~10% of all fresh water in lakes on Earth. However, an efficient process for capturing and delivering water from air, especially at low humidity levels (down to 20%), has not been developed. We report the design and demonstration of a device based on a porous metal-organic framework {MOF-801, [Zr6O4(OH)4(fumarate)6]} that captures water from the atmosphere at ambient conditions by using low-grade heat from natural sunlight at a flux of less than 1 sun (1 kilowatt per square meter). This device is capable of harvesting 2.8 liters of water per kilogram of MOF daily at relative humidity levels as low as 20% and requires no additional input of energy.
1,041 citations
TL;DR: In this article, a PCM nanocomposite, consisting of a mixture of two organic PCMs (referred to as eutectic gel PCM) and minimal amount (0.5) of nanographite (NG) as a supporting material, was prepared.
55 citations
TL;DR: In this article, the authors demonstrate the concept of a thermophysical battery, which operates by storing thermal energy and subsequently releasing it to provide heating and cooling on demand, taking advantage of the adsorption-desorption and evaporation-condensation mechanisms.
51 citations
TL;DR: In this article, phase change materials can provide large heat storage density with low volume, but their low thermal conductivity limits their heat transfer capabilities, since carbonaceous nanoparticles have a go...
Abstract: Phase change materials can provide large heat storage density with low volume. But their low thermal conductivity limits their heat transfer capabilities. Since carbonaceous nanoparticles have a go...
20 citations
01 Jan 2017
TL;DR: A review of current experimental studies on variations in thermophysical properties of phase change material (PCM) due to dispersion of highly-conductive nanoparticles, coined as nanoparticle-enhanced PCMs (NePCMs), is presented in this article.
Abstract: A review of current experimental studies on variations in thermophysical properties of phase change material (PCM) due to dispersion of highly-conductive nanoparticles , coined as nanoparticle-enhanced PCMs (NePCMs), is presented in this article. The NePCMs may be considered as a solution to improve latent heat thermal energy storage performance. Thermophysical properties such as thermal conductivity, latent heat, viscosity and super cooling of PCMs could be changed for different physical properties of dispersed nanoparticle such as size, shape, concentration and surface properties. The present review focuses on the studies that describe the effect of addition of nanoparticles on the thermophysical properties of PCM with the help of available explanations in the literature.
18 citations
Patent•
30 Nov 2017TL;DR: In this article, a water-harvesting method and system can include vapor adsorption using a porous metal-organic framework in ambient air with low relative humidity, typical of the levels found in most dry regions of the world.
Abstract: A water-harvesting system can operate with a material that can take up and release water with minimum energy requirements and powered by low-grade energy sources, such as sunlight, in order to potentially allow its deployment into households, especially those located in sunny regions. A water-harvesting method and system can include vapor adsorption using a porous metal-organic framework. In certain embodiments, the porous metal-organic framework can include metal-organic framework in ambient air with low relative humidity, typical of the levels found in most dry regions of the world.
16 citations
TL;DR: Using heat transfer and thermodynamics principles, this work shows how Bui et al.
Abstract: The Comment by Meunier states that the process we described in our report cannot deliver the claimed amount of liquid water in an arid climate. This statement is not valid because the parameters presented in our study were inappropriately combined to draw misguided conclusions.
13 citations
01 May 2017
TL;DR: In this paper, a biporous membrane based thermal management solution for ultra-high heat flux dissipation from high performance integrated circuits is presented, which utilizes thermally-connected, mechanically-supported, high capillarity membranes that maximize thin film evaporation and high permeability liquid supply channels that minimize viscous pressure losses.
Abstract: We investigated the evaporative cooling performance of a nanoporous membrane based thermal management solution designed for ultra-high heat flux dissipation from high performance integrated circuits. The biporous evaporation device utilizes thermally-connected, mechanically-supported, high capillarity membranes that maximize thin film evaporation and high permeability liquid supply channels that minimize viscous pressure losses. The 600 nm thick membrane was created on a silicon on insulator (SOI) wafer, fusion-bonded to a separate wafer with larger liquid channels. Overall device performance arising from non-uniform heating and evaporation of methanol was captured experimentally. Heat fluxes up to 412 W/cm2 over an area of 0.4×5 mm, at a temperature rise of 24.1 K from the heated substrate to ambient vapor, were obtained. These results are in good agreement with a high-fidelity coupled fluid convection and solid conduction compact model that incorporates non-equilibrium and sub-continuum effects at the liquid-vapor interface. This work provides a proof-of-concept demonstration of our biporous evaporation device. Simulations of the validated model at optimized operating conditions and with improved working fluids, predict heat dissipation in excess of 1 kW/cm2 with a device temperature rise under 30 K, for this scalable cooling approach.
7 citations