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Pyroelectric waste heat energy harvesting using the Olsen cycle on Pb(Zr, Ti)O <sub/>3</sub> -Pb(Ni, Nb)O <sub/>3</sub> ceramics
摘要： This paper is concerned with direct energy conversion of waste heat into electrical energy by performing the Olsen cycle on lead nickel niobate zirconate titanate (PNNZT) pyroelectric ceramics undergoing a relaxor-ferroelectric phase transition. First, isothermal bipolar displacement vs. electric field hysteresis loops were measured for different temperatures and electric field spans. The Curie temperature varied between 150 °C and 240 °C as the electric field increased from zero up to 3 MV/m. The energy and power densities of the Olsen cycle on PNNZT were measured by cycling the specimens over a wide range of temperatures, electric fields, and frequencies. A maximum energy density of 1417 J/L/cycle was recorded with 200 μm thick PNNZT cycled at 0.033 Hz between temperatures 20 °C and 240 °C and electric fields 0.3 MV/m and 9.0 MV/m. To the best of our knowledge, this is the largest energy density ever obtained experimentally for any pyroelectric material. In addition, a maximum power density of 78 W/L was measured by cycling the material temperature between 20 °C and 220 °C and applying the electric field between 0.3 MV/m and 9.0 MV/m at 0.09 Hz.
关键词： waste heat,pyroelectric,Olsen cycle,energy harvesting,PNNZT
更新于2025-09-23 15:21:21
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Thermophotovoltaic applications in waste heat recovery systems: example of GaSb cell
摘要： In this study, it is aimed at evaluating real data in high temperature GaSb cell thermophotovoltaic (TPV) systems. The TPV systems are considered as an alternative energy source in terms of efficient use of waste heat, cost and efficiency. The TPV system can be defined as a system that converts waste heat energy emitted from heat sources into electrical energy at high temperature. In this context, efficiency and parameters of TPV GaSb cells have been determined in laboratory conditions. The conversion of the high temperature applied to the cell to electrical energy has been investigated by selecting the GaSb photovoltaic cell as the cell type. According to the analysis have been done so far, TPV high-temperature real graphics have been obtained using GaSb cell. The temperature parameters used are, namely, cell temperature and source temperature. With these graphs, energy efficiency, fill factor, effect of open-circuit voltage and short-circuit current values have been determined. While the efficiency value of the GaSb TPV cell systems was calculated, the radiation source temperature values have been taken in increments of 300 K between 1300 and 3100 K. In this analysis, the optimum energy conversion efficiency values of GaSb solar cell structure have been detected to be 21.57%. Opinions about the feasibility, efficiency and development of thermophotovoltaic energy conversion systems are stated, and suggestions are presented.
关键词： electricity generation,GaSb cell,waste heat,thermophotovoltaic,real data,photovoltaic cell
更新于2025-09-23 15:21:01
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High efficient nanostructured PbSe0.5Te0.5 exhibiting broad figure-of-merit plateau
摘要： To have a very good energy conversion efficiency, thermoelectric (TE) material should exhibit higher figure-of-merit (ZT) for broad range of temperatures. In that direction, n-type PbTe0.5Se0.5 material with enhanced and temperature insensitive figure-of-merit was developed through nanostructured approach. A temperature insensitive ZT of 0.7 was observed from 400 K to 600 K. The enhanced and stable ZT over a wide temperature range was ascribed to the presence of various types of nanostructures that facilitated scattering of mid and long wavelength phonons, keeping the thermal conductivity low in addition to scattering low energy charge carriers elevating the Seebeck coefficient (-380 m VK-1 at 600 K). Most thermoelectric n-type materials such as PbQ (Q = Te, Se) materials exhibits very low ZT at room temperature which hampers the overall conversation efficiency. However, the developed material exhibits highest ZT at room temperature among PbQ (Q = Te,Se) materials that enables this material to be used in wearable thermoelectric applications. In this study, newly introduced technique was adopted to calculate TE conversion efficiency, which addresses overestimations of conventional efficiency calculations. The developed material showed power generation efficiency higher than many state-of-the-art TE n-type materials in 300 K-600 K range making it a competitive material for waste heat recovery applications.
关键词： waste heat recovery,engineering figure-of-merit,sustainable energy,TE power generation efficiency,nanoprecipitates,lead selenides
更新于2025-09-19 17:15:36
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Theoretical Analysis of Hybrid Dense-Array Concentrator Photovoltaic and Stirling Engine System
摘要： In this paper, we analyse the performance of newly proposed hybrid dense-array concentrator photovoltaic (CPV) and gamma type low temperature differential (LTD) Stirling engine. Schmidt Analysis was applied to compute the performance of LTD Stirling engine while computational fluid dynamic was employed to simulate the heat transfer in the CPV receiver. The simulated result was subsequently used to determine the power conversion efficiency of the hybrid system. Three major parameters have been considered to optimize the overall system performance including water inlet temperature, water flow rate, and CPV surface temperature. In our theoretical analysis, the highest efficiency of the hybrid system ranging 37.8 - 38.0 % can be achieved at water inlet temperature of 90°C. It has shown significant improvement by producing 10.1 -10.7 % extra energy as compared to the efficiency of CPV system without waste heat recovery.
关键词： waste heat recovery,low temperature differential Stirling engine,Concentrator photovoltaic,conversion efficiency,Schmidt analysis,non-imaging dish concentrator
更新于2025-09-12 10:27:22
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Advancing photovoltaics and thermophotovoltaics with supradegeneracy
摘要： An ongoing challenge facing photovoltaics (PV) and thermophotovoltaics (TPV) is to improve the relatively poor efficiency with which they convert blackbody radiation into electricity. Analysis indicates that a recently proposed phenomenon from statistical mechanics – supradegeneracy – might boost this efficiency and increase system power densities. Supradegeneracy might also expand the palette of attractive PV/TPV materials, allow lower operating temperatures for TPVs, and thereby increase their robustness, reliability, and lifespan. Laboratory tests of the supradegeneracy concept have begun.
关键词： Photovoltaics,Second law of thermodynamics,Thermophotovoltaics,Waste heat,Supradegeneracy
更新于2025-09-12 10:27:22
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A Review of Advances in Thermophotovoltaics for Power Generation and Waste Heat Harvesting
摘要： The vast majority of power generation in the United States today is produced through the same processes as it was in the late-1800s: heat is applied to water to generate steam, which turns a turbine, which turns a generator, generating electrical power. Researchers today are developing solid-state power generation processes that are more befitting the 21st-century. Thermophotovoltaic (TPV) cells directly convert radiated thermal energy into electrical power, through a process similar to how traditional photovoltaics work. These TPV generators, however, include additional system components that solar cells do not incorporate. These components, selective-emitters and filters, shape the way the radiated heat is transferred into the TPV cell for conversion and are critical for its efficiency. Here, we present a review of work performed to improve the components in these systems. These improvements will help enable TPV generators to be used with nearly any thermal source for both primary power generation and waste heat harvesting.
关键词： Power Generation,Thermophotovoltaics,Waste Heat Harvesting,Selective-emitters,Filters
更新于2025-09-11 14:15:04