Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session S21: Energy-related Thermal Phenomena |
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Sponsoring Units: GERA Chair: Sarbajit Banerjee, Texas A&M University Room: 302 |
Thursday, March 5, 2020 11:15AM - 11:27AM |
S21.00001: Towards high power density, high efficiency thermophotovoltaic energy conversion system in the near field Rohith Mittapally, Linxiao Zhu, Anthony Fiorino, Dakotah Thompson, Edgar Meyhofer, Pramod Reddy Solid-state energy conversion holds promise for efficient extraction of electricity from different heat sources like solar and industrial waste heat. In particular, thermophotovoltaic (TPV) system involves a hot emitter radiating photons that excite electron hole pairs in a photovoltaic (PV) cell. Most TPV architectures in the far-field demonstrate very low power densities. Several theoretical proposals have shown that dramatic enhancement in power density can be achieved by reducing the gap to tens of nanometers where evanescent waves start contributing to power transfer. However, such demonstrations have been elusive due to the challenge of maintaining nano separations between a hot emitter (~1000 K) and a cold cell (~300 K). Here, we will first describe how high resolution calorimetry and custom-built nano-positioning platform have made possible, the first demonstration of ~40 fold increase in the power output, compared to far field, when the gap between the PV cell and thermal emitter at 650 K is reduced from ~10 µm to 60 nm. Further, we will describe ongoing efforts to achieve increases in both power output and efficiencies by engineering emitters that can reach high temperatures. |
Thursday, March 5, 2020 11:27AM - 11:39AM |
S21.00002: Highly Efficient Solar Steam Generation by Glassy Carbon Foam Coated with Two-Dimensional Metal Chalcogenides Zeeshan Tahir, Sungdo Kim, Farman Ullah, Joon I Jang, Yong Soo Kim Steam generation by ecofriendly solar energy has immense potential in terms of low-cost power generation, desalination, sanitization and wastewater treatment. Herein, highly efficient steam generation in a bilayer solar steam generator (BSSG) is demonstrated which is comprised of a large-area SnSe-SnSe2 layer deposited on glassy carbon foam (CF). Both CF and SnSe-SnSe2 possess high photothermal conversion capabilities and low thermal conductivities. The combined bilayer system cumulatively converts input solar light into heat through phonon-assisted transitions in the indirect-bandgap SnSe-SnSe2 layer, together with trapping of sunlight via multiple scattering due to the porous morphology of the CF. This synergistic effect leads to efficient broadband solar absorption. Moreover, the low out-of-plane thermal conductivities of SnSe-SnSe2 and CF confine the generated heat at the evaporation surface, resulting in a significant reduction of heat losses. Additionally, the hydrophilic nature of the acid-treated CF offers effective water transport via capillary action, required for efficient solar steam generation in a floating form. A high evaporation rate (1.28 kgm-2h-1) and efficiency (84.1%) are acquired under one sun irradiation. |
Thursday, March 5, 2020 11:39AM - 11:51AM |
S21.00003: Highly Efficient TiO2 Nanorods@CF based Solar Steam Generator Sungdo Kim, Zeeshan Tahir, Anh Nguyen, Jongwoo Park, Yong Soo Kim Harvesting solar energy via steam generation is an efficient way for brine and sewage water treatment. Directly bulk water heating with natural light yields low evaporation rates, owing to immense heat losses and its high heat capacity of water. Herein, we report styrofoam supported solar steam generator (SSG) comprised of glassy carbon foam (CF) covered with TiO2 nanorods (TNRs). It shows a record high evaporation rate of 3.14 kgm-2h-1 under one sun irradiation. Such a high evaporation rate is mainly attributed to the synergetic effect of significant heat localization and reduction in enthalpy. Employing a low thermal conductivity, styrofoam naturally isolates the bulk water yielding an enhanced localization of heat. Concurrently, rapid water transport to SSG is ensured via a 2D air-laid paper as a wicking material. Moreover, the water molecules adsorbed in the form of clusters to the edges and tips of TNRs are more likely evaporate as clusters and thereby effectively reducing the enthalpy. Besides, the SSG offers broadband solar absorption displaying excellent photothermal conversion capability. Finally the facile method, low cost and longevity make our SSG a good candidate for application on a large scale. |
Thursday, March 5, 2020 11:51AM - 12:03PM |
S21.00004: Continuum Model of Underground Thermal Energy Storage Applied to Efficiency Optimization Anders Carlsson A major obstacle to extensive deployment of renewable energy sources is their seasonal intermittency. Borehole thermal energy storage (BTES) is an inexpensive technology that can mitigate this intermittency. Hot water is pumped from the center to the edge of an array of boreholes to heat it in the summer, and heat is discharged in winter by reversing the process. Mathematical modeling is key to efficiency improvement. I develop an approach to modeling BTES that is simpler than existing approaches that use either embedded symmetrized borehole temperature fields or explicit simulation of the full 3d geometry. This approach focuses on the average radial flow of water, and develops coupled 1d reaction-diffusion equations for the water and soil temperatures. These are supplemented by a time-dependent heat-transfer coefficient. With two adjustable parameters, the model fits four-year temperature data at 10-minute intervals from the Drake Landing Solar Community closely. I use the model to explore possible modifications to the charging and discharging strategies. A strategy in which heated water is discharged at variable distances can increase the efficiency by over 20% in some cases. |
Thursday, March 5, 2020 12:03PM - 12:15PM |
S21.00005: Rattling-Induced Ultralow Lattice Thermal Conductivity in Simple Systems Rinkle Juneja, Abhishek Singh Rattling motion is one of the significant phenomena for achieving notable reduction in the thermal conductivity in complex crystal systems. To carry forward the advantages of rattling to simple crystal systems, we explored it in simpler cubic compounds AgIn5S8 and CuIn5S8. The weak and anisotropic bonding of Ag and Cu with the neighboring In and S causes the rattling motion, which result in very shallow anharmonic potential well for the rattlers Ag and Cu. The phonon spectra of these compounds have multiple avoided crossing of optical and acoustic modes, which are a signature of rattling motion. This leads to ultralow thermal conductivity. Even though Ag atoms contribute to the valence band states, the rattler modes of Ag do not scatter carriers significantly, leaving the electronic transport virtually unaffected. A combination of favorable thermal and electronic transport results in unprecedented figure of merit of 2.2 in p-doped AgIn5S8 at 1000 K. The proposed idea of having rattlers in simpler systems can be extended to a wider class of materials, which would accelerate the development of thermoelectric modules for waste energy harvesting. |
Thursday, March 5, 2020 12:15PM - 12:27PM |
S21.00006: On photon thermal Hall effect and persistent heat current in radiative heat transfer Cheng Guo, Yu Guo, Shanhui Fan We study the photon thermal Hall effect and the persistent heat current in radiative heat transfer. We show that the photon thermal Hall effect is not a uniquely nonreciprocal effect; it can arise in some reciprocal systems with broken mirror symmetry. This is in contrast with the persistent heat current, which is a uniquely non-reciprocal effect that can not exist in any reciprocal system. Nevertheless, for a specific class of systems with C4 rotational symmetry, we note that the photon thermal Hall effect is uniquely nonreciprocal, and moreover there is a direct connection between the persistent heat current and the photon thermal Hall effect. In the near-equilibrium regime, the magnitude of the photon thermal Hall effect is proportional to the temperature derivative of the persistent heat current in such systems. Therefore, the persistent heat current as predicted for the equilibrium situation can be probed by the photon thermal Hall effect away from equilibrium. |
Thursday, March 5, 2020 12:27PM - 12:39PM |
S21.00007: Self-sustaining Thermophotonic Circuits Bo Zhao, Siddharth Buddhiraju, Parthiban Santhanam, Kaifeng Chen, Shanhui Fan Photons represent one of the most important heat carriers. The ability to convert photon heat flow to electricity is therefore of substantial importance for renewable energy applications. However, photon-based systems that convert heat to electricity, including thermophotovoltaic systems where photons are generated from passive thermal emitters, have long been limited by low power density. This limitation persists even with near-field enhancement techniques. Thermophotonic systems, which utilize active photon emitters such as light-emitting diodes, have the potential to significantly further enhance the power density. However, this potential has not been realized in practice, due in part to the fundamental difficulty in thermodynamics of designing a self-sustaining circuit that enables steady-state power generation. Here, we overcome such difficulty by introducing a configuration where the light-emitting diodes are connected in series, and thus multiple photons can be generated from a single injected electron. As a result, we propose a self-sustaining thermophotonic circuit where the steady-state power density can exceed thermophotovoltaic systems by many orders of magnitude. This work points to possibilities for constructing heat engines with light as the working medium. |
Thursday, March 5, 2020 12:39PM - 12:51PM |
S21.00008: Demonstration of thermal energy conversion though radiating optical rectennas for night harvesting applications Amina Belkadi, Garret Moddel Night harvesting, where heat is harvested from the temperature difference between Earth and deep space, promises clean energy when sunlight is not available. The low efficiency of available thermal-to-electrical energy conversion technologies has been the largest barrier in the commercial pursuit of this technology. We present a new approach using radiating optical rectennas – femtosecond-fast metal-insulator-metal (MIM) diodes and micron-scale antennas – to overcome the limitations of low efficiency for low temperature differences (< 100 °C). We experimentally demonstrate the basic principle of thermal-to-electrical energy conversion using a Ni-NiO-Al2O3-Cr-Au MIM diode-based optical rectenna, with a transmission line compensation structure to enhance the coupling efficiency between antenna and diode at terahertz frequencies. For a temperature gradient of 80° C, the device generates an open circuit voltage of 300 mV, corresponding to a power of at least 93 mW/m2. Under practical operating conditions, this technology has the potential to exceed similar technologies exploiting radiative cooling. |
Thursday, March 5, 2020 12:51PM - 1:03PM |
S21.00009: Relaxor-ferroelectrics: An efficient material for waste-heat harvesting Amrit Sharma, Makhes K Behera, Sangram K Pradhan, Carl E Bonner, Messaoud Bahoura The need for efficient energy utilization is driving research to harvest waste-heat, which is ubiquitous, abundant, and free. Thermal energy harvesting for low power electronic devices using ferroelectric materials is one of the emerging areas of research because they possess spontaneous polarization and exhibit excellent pyroelectric coefficients. These materials are unique as they only sense time-dependent temperature change to generate electric power. We have grown lead-free BaZr0.2Ti0.8O3 (BZT)/Ba0.7Ca0.3TiO3 (BCT) multilayer heterostructures on SrRuO3 (SRO) buffered SrTiO3 (STO) single crystal substrates by optimized pulsed laser deposition (PLD) technique. We have developed a device with a capacitive structure of 200 nm thick BZT/BCT multilayer heterostructures sandwiched between platinum top and SRO bottom electrodes. The device demonstrates excellent pyroelectric current of ~600 nA in response to temperature fluctuation of 11 K using a laser diode of wavelength 850 nm with a repetition rate of 0.1 Hz and power 150 mW. Our findings suggest that the relaxor-ferroelectric thin film may be competitive with thermoelectric materials for low-grade thermal harvesting. |
Thursday, March 5, 2020 1:03PM - 1:15PM |
S21.00010: Inorganic Multilayer Emitter for Passive Daytime Radiative Cooling Dongwoo Chae, Pil-Hoon Jung, Soomin Son, Yuting Liu, Heon Lee Passive radiative cooling has been actively researched to compromise problems of active cooling. Passive radiative cooling refers to the cooling of a surface using optical properties without the supply of electricity from the external. In this study, Ag/Al2O3/Si3N4/SiO2 multilayer structure was suggested and optimized by Particle Swarm Optimization (PSO). The multilayer was fabricated by E-beam evaporation and PECVD. Fabricated multilayer also has excellent radative cooling properties with just three IR emissive layers of Al2O3, Si3N4, and SiO2. In addition, since Al2O3, Si3N4, and SiO2 is generally used as passivation layer, it has higher durability compared to polymer-based radiative cooler. The cooling temperature of the multilayer was measured using self-customized external cooling temperature measurement system. The cooling performance was calculated based on the optical properties of the multilayer using self-developed MATLAB tool. In Seoul which is mid-latitude and have relatively humid climate, the multilayer had cooling temperature of around 8oC during the daytime. And the calculated net cooling power and cooling temperature of the multilayer resonator was 66.0W/m2 and 7.64oC respectively at T = 300K |
Thursday, March 5, 2020 1:15PM - 1:27PM |
S21.00011: Low-temperature heat conduction in the Metal-Organic Framework Perovskite [C(NH$_2$)$_3$]Ni(HCOO)$_3$ Dharmendra Shukla, Thomas M. Carlino, Amy M. Scott, Joshua Cohn We report thermal conductivity ($\kappa$) measurements on single crystals of the metal-organic framework perovskite compound [C(NH$_2$)$_3$]Ni(HCOO)$_3$ in the temperature range 5K~$\le T\le$~300K. Measurements with heat flow along different crystallographic directions and under applied electric field will be presented and compared to $\kappa$ measurements on the closely related compounds$^a$ [C(NH$_2$)$_3$]X(HCOO)$_3$ (X=Zn, Cu).Thermal hysteresis, observed in the range 80K~$\leq T\le$~300K, will also be discussed. |
Thursday, March 5, 2020 1:27PM - 1:39PM |
S21.00012: Radiative Cooling Under an Urban Glow and a Narrow View of the Sky Jyotirmoy Mandal, Aaswath Raman Passive radiative cooling (PRC) of objects involves radiative heat loss into the cold outer space through the long wavelength infrared (LWIR) atmospheric transmission window. Due to its passive operation and net cooling effect, it is a promising alternative or complement to electrical cooling.1-2 For efficient PRC of objects, an unimpeded view of the sky is ideal. However, the view of the sky is often limited - for instance, the walls of buildings have > 50% of their field of view subtended by the earth, while low-lying roofs are overshadowed by taller buildings. Moreover, objects on earth become heat sources under sunlight. Therefore, buildings with hot terrestrial objects in view experience reduced cooling or even heating. |
Thursday, March 5, 2020 1:39PM - 1:51PM |
S21.00013: Neutron studies of the structure and dynamics of barocaloric Ammonium Sulfate Helen Walker, Bernet Meijer, Guanqun Cai, Shurong Yuan, Franz Demmel, Helen Playford, Anthony Phillips Conventional vapour-compression refrigeration relies on refrigerants that contribute both to global warming and ozone depletion. Barocaloric materials, in which a large isothermal entropy change is associated with a pressure-induced phase transition, offer an eco-friendly alternative. |
Thursday, March 5, 2020 1:51PM - 2:03PM |
S21.00014: A new source of thermal power Millicent Gikunda, Paul M Thibado Due to an increasing need to produce self-charging, portable, implantable and wireless electronics with extended lifespans, development of energy harvesting systems is becoming increasingly important. Much emphasis has been placed on scavenging for vibrational energy as an alternative power source. A recent notable breakthrough is the discovery that when relaxed, sheets of freestanding graphene exhibit a rippled morphology, in which adjacent regions alternate between concave and convex curvature. These ripples form due to self-compression. |
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