Global sensitivity analysis of borehole thermal energy storage efficiency on the heat exchanger arrangement

2018 ◽  
Vol 166 ◽  
pp. 106-119 ◽  
Author(s):  
Jerzy Wołoszyn
Keyword(s):  
Sensitivity Analysis ◽  
Energy Storage ◽  
Heat Exchanger ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Global Sensitivity Analysis ◽  
Storage Efficiency ◽  
Global Sensitivity ◽  
Energy Storage Efficiency

scholarly journals Si3N4 nanofelts/paraffin composites as novel thermal energy storage architecture

2020 ◽  
Vol 56 (2) ◽  
pp. 1537-1550
Author(s):  
Francesco Valentini ◽  
Andrea Dorigato ◽  
Alessandro Pegoretti ◽  
Michele Tomasi ◽  
Gian D. Sorarù ◽  
...  
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Composite Structures ◽  
Liquid Paraffin ◽  
Stored Energy ◽  
Storage Efficiency ◽  
Novel Material ◽  
Energy Storage Efficiency ◽  
Change Material

Abstract The environmental problems associated with global warming are urging the development of novel systems to manage and reduce the energy consumption. An attractive route to improve the energy efficiency of civil buildings is to store the thermal energy thanks, during heating, to the phase transition of a phase-change material (as paraffin) from the solid to the liquid state and vice versa. The stored energy can be then released under cooling. Herein, we developed a novel material (nanofelt) constituted by Si3N4 nanobelts able to absorb huge amounts of liquid paraffin in the molten state and to act as an efficient shape stabilizer. The nanofelt manufacturing technology is very simple and easy to be scaled-up. The effect of the Si3N4 nanofelts density and microstructure on the paraffin sorption and leakage and on the thermal properties of the resulting composite structures is investigated. It is shown that the produced Si3N4/paraffin composites are able to retain enormous fractions of paraffin (up to 70 wt%) after 44 day of desorption test on absorbent paper towel. The thermal energy storage efficiency measured through calorimetric tests is as high as 77.4% in heating and 80.1% in cooling.

Comprehensive Parametric Analysis and Sensitivity Study of Latent Heat Thermal Energy Storage System in Concentrated Solar Power Plants

2018 ◽  
Author(s):  
Hermes Chirino ◽  
Ben Xu
Keyword(s):  
Energy Storage ◽  
Latent Heat ◽  
Parameter Space ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Parametric Analysis ◽  
Sensitivity Study ◽  
Storage Efficiency ◽  
Concentrated Solar Power ◽  
Energy Storage Efficiency

Compared to Solar Photovoltaics (PV), Concentrated Solar Power (CSP) can store the excess solar thermal energy, extend the power generation at night and cloudy days, and levelize the mismatch between energy demand and supply. To make CSP competitive, Thermal Energy Storage (TES) system filled with phase change material (PCM) is a promising indirect energy storage technique, compared to the TES system using concrete or river rocks. It is of great interests to solar thermal community to apply the latent heat thermal energy storage (LHTES) system for large scale CSP application, because PCMs can store more thermal energy due to the latent heat during the melting/freezing process. Therefore, a comprehensive parametric analysis of LHTES system is necessary in order to improve its systematic performance, since LHTES system has a relatively low energy storage efficiency compared to TES systems using sensible materials. In this study, an 11-dimensionless-parameter space of LHTES system was developed, by considering only the technical constraints (materials properties and operation parameters), instead of economic constraints. Then the parametric analysis was performed based on a 1D enthalpy-based transient model, and the energy storage efficiency was used as the objective function to minimize the number of variables in the parameter space. It was found that Stanton number (St), PCM radius (r), and void fraction (ε) are the three most important ones. The sensitivity study was conducted then based on the three dimensionless-parameter space which will significantly influence the system performance. The results of this study make LHTES system competitive with TES system using sensible materials in terms of energy storage efficiency.

scholarly journals Operational Performance and Load Flexibility Analysis of Japanese Zero Energy House

2021 ◽  
Vol 18 (13) ◽  
pp. 6782
Author(s):  
Xiaoyi Zhang ◽  
Weijun Gao ◽  
Yanxue Li ◽  
Zixuan Wang ◽  
Yoshiaki Ushifusa ◽  
...  
Keyword(s):  
Energy Storage ◽  
Heat Loss ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Heat Energy ◽  
Storage Efficiency ◽  
Zero Energy ◽  
Indoor Temperature ◽  
Energy Storage Efficiency ◽  
Pv Generation

ZEHs (Zero Energy House) featuring energy-efficient designs and on-site renewable integration are being widely developed. This study introduced Japanese ZEHs with well-insulated thermal envelopes and investigated their detailed operational performances through on-site measurements and simulation models. Measurement data show that ZEHs effectively damped the variation of indoor air temperature compared to conventional houses, presenting great ability to retain inside heat energy, and are expected to potentially deliver energy flexibility as a virtual thermal energy storage medium. We developed a simplified thermal resistance–capacitance model for a house heating system; response behaviors were simulated under various scenarios. Results compared the variations of indoor temperature profiles and revealed the dependence of load flexibility on the building’s overall heat loss performance. We observed that overall heat loss rate played a crucial role in building heat energy storage efficiency; a well-insulated house shortened the heat-up time with less energy input, and extended the delayed period of indoor temperature under intermittent heating supply; a high set-point operative temperature and a low ambient temperature led to lower virtual thermal energy storage efficiency. The preheating strategy was simulated as an effective load-shifting approach in consuming surplus PV generation; approximately 50% of consumed PV generation could be shifted to replace grid import electricity for room heating during the occupied period.

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