Performance of a Pebble Bed Thermal Storage Integrated with Concentrating Parabolic Solar Collector for Cooking

Cooking using biomass, which is commonly practiced in developing countries, causes rampant deforestation and exposure to emission. Hence, utilization of solar energy for cooking is a green solution. As solar radiation is not available at every hour of the day, thermal storage is essential for availing thermal energy at required time of use. Therefore, this work investigates the efficiency of solar cooker with parabolic concentrating collector integrated with thermal storage using 1D finite difference computational model. A cook stove on packed pebble bed thermal storage having 0.3 m diameter and 0.9 m height and a storage capacity of 40.1 MJ of energy during a clear day and 12.85 MJ energy was simulated for charging and discharging (cooking), under Addis Ababa climatic condition for days, with highest and lowest solar irradiance and thermal storage efficiency of 66.7%, cooker thermal efficiency of 45% during discharging of heat by forced convection, and 41% during discharging of heat by conduction, were obtained for the day with the highest solar irradiance. The overall efficiency of the cook stove with thermal storage was 30% and 22% for discharging by forced convection and conduction, respectively. For the day with lowest beam solar irradiance, the storage, thermal and overall efficiencies were 70.9%, 31.1% and 22.0%, respectively. Hence, it can be concluded that solar concentrating cookers with thermal storage can have an overall cooking efficiency between 22% and 30% on a clear sky day when the Sun is overhead in tropical areas.

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ANALYSIS OF THE IMPACT OF U-SHAPED STRUCTURE FOR HEADS OF LOOP THERMOSYPHON SOLAR WATER HEATER ON THERMAL STORAGE EFFICIENCY

Journal of Enhanced Heat Transfer ◽

10.1615/jenhheattransf.2017015985 ◽

2016 ◽

Vol 23 (3) ◽

pp. 175-195

Author(s):

Chien Huang ◽

Wei-Keng Lin ◽

Sung-Ren Wang

Keyword(s):

Thermal Storage ◽

Solar Water Heater ◽

Storage Efficiency ◽

Water Heater ◽

Solar Water ◽

The Impact

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Utility-Scale PV-Battery versus CSP-Thermal Storage in Morocco: Storage and Cost Effect under Penetration Scenarios

Energies ◽

10.3390/en14154675 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4675

Author(s):

Ayat-allah Bouramdane ◽

Alexis Tantet ◽

Philippe Drobinski

Keyword(s):

Storage Capacity ◽

Low Cost ◽

Thermal Storage ◽

Solar Pv ◽

Storage Duration ◽

Maximum Cost ◽

Pv Inverter ◽

The Mean ◽

Mean Variance Portfolio ◽

Utility Scale

In this study, we examine how Battery Storage (BES) and Thermal Storage (TES) combined with solar Photovoltaic (PV) and Concentrated Solar Power (CSP) technologies with an increased storage duration and rental cost together with diversification would influence the Moroccan mix and to what extent the variability (i.e., adequacy risk) can be reduced; this is done using recent (2013) cost data and under various penetration scenarios. To do this, we use MERRA-2 climate reanalysis to simulate hourly demand and capacity factors (CFs) of wind, solar PV and CSP without and with increasing storage capabilities—as defined by the CSP Solar Multiple (SM) and PV Inverter Loading Ratio (ILR). We adjust these time series to observations for the four Moroccan electrical zones over the year 2018. Our objective is to maximize the renewable (RE) penetration and minimize the imbalances between RE production and consumption considering three optimization strategies. We analyze mixes along Pareto fronts using the Mean-Variance Portfolio approach—implemented in the E4CLIM model—in which we add a maximum-cost constraint to take into account the different rental costs of wind, PV and CSP. We propose a method to calculate the rental cost of storage and production technologies taking into account the constraints on storage associated with the increase of SM and ILR in the added PV-BES and CSP-TES modules, keeping the mean solar CFs fixed. We perform some load bands-reduction diagnostics to assess the reliability benefits provided by each RE technology. We find that, at low penetrations, the maximum-cost budget is not reached because a small capacity is needed. The higher the ILR for PV, the larger the share of PV in the mix compared to wind and CSP without storage is removed completely. Between PV-BES and CSP-TES, the latter is preferred as it has larger storage capacity and thus stronger impact in reducing the adequacy risk. As additional BES are installed, more than TES, PV-BES is favored. At high penetrations, optimal mixes are impacted by cost, the more so as CSP (resp., PV) with high SM (resp., ILR) are installed. Wind is preferably installed due to its high mean CF compared to cost, followed by either PV-BES or CSP/CSP-TES. Scenarios without or with medium storage capacity favor CSP/CSP-TES, while high storage duration scenarios are dominated by low-cost PV-BES. However, scenarios ignoring the storage cost and constraints provide more weight to PV-BES whatever the penetration level. We also show that significant reduction of RE variability can only be achieved through geographical diversification. Technological complementarity may only help to reduce the variance when PV and CSP are both installed without or with a small amount of storage. However, the diversification effect is slightly smaller when the SM and ILR are increased and the covariances are reduced as well since mixes become less diversified.

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A one-parameter family of clear-sky solar irradiance models adapted for different aerosol types

Journal of Renewable and Sustainable Energy ◽

10.1063/5.0038619 ◽

2021 ◽

Vol 13 (2) ◽

pp. 023701

Author(s):

Robert Blaga ◽

Delia Calinoiu ◽

Marius Paulescu

Keyword(s):

Solar Irradiance ◽

Parameter Family ◽

Clear Sky ◽

Aerosol Types

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A Numerical Model of In-Channel Pebble Bed Thermal Storage for a Solar Chimney

Volume 6: Energy, Parts A and B ◽

10.1115/imece2012-88356 ◽

2012 ◽

Author(s):

Brandon Schulte ◽

O. A. Plumb

Keyword(s):

Numerical Model ◽

Present Model ◽

Thermal Storage ◽

Implicit Time ◽

Heat Transfer Characteristics ◽

Solar Chimney ◽

Pebble Bed ◽

One Dimensional ◽

Time Stepping ◽

Daily Energy

In this study, solar chimney performance is numerically modeled. Previously published models have considered water bags and natural earth as means to store daytime thermal energy for nighttime operation of the system. The present model considers in-channel pebble bed thermal storage. A one-dimensional, implicit time stepping numerical model is developed to predict solar chimney performance throughout a 24 hour period. The model is partially verified with available experimental data. The daily energy, daily efficiency and heat transfer characteristics of the solar chimney with pebble bed thermal storage are summarized. The numerical simulation showed that by introducing a pebble bed, nightly exit velocities reach 40% of the peak daytime velocity. However, the daily kinetic energy delivered by a solar chimney with pebble bed thermal storage is much less than a traditional solar chimney, suggesting pebble bed thermal storage is more practicable in building heating applications as opposed to power generation.

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Albedo and estimates of net radiation for green beans under polyethylene cover and field conditions

Pesquisa Agropecuária Brasileira ◽

10.1590/s0100-204x1999001000002 ◽

1999 ◽

Vol 34 (10) ◽

pp. 1763-1774 ◽

Cited By ~ 1

Author(s):

José Leonaldo de Souza ◽

João Francisco Escobedo ◽

Maria Terezinha Trovareli Tornero

Keyword(s):

Solar Irradiance ◽

Field Conditions ◽

Net Radiation ◽

Phaseolus Vulgaris L ◽

Green Beans ◽

Phenological Stages ◽

Independent Variables ◽

Clear Sky ◽

Solar Elevation ◽

Global Irradiance

This paper describes the albedo (r) and estimates of net radiation and global solar irradiance for green beans crop (Phaseolus vulgaris L.), cultivated in greenhouse with cover of polyethylene and field conditions, in Botucatu, SP, Brazil (22º 54' S; 48º 27' W; 850 m). The solar global irradiance (Rg) and solar reflected radiation (Rr) were used to estimate the albedo through the ratio between Rr and Rg. The diurnal curves of albedo were obtained for days with clear sky and partially cloudy conditions, for different phenological stages of the crop. The albedo ranged with the solar elevation, the environment and the phenological stages. The cloudiness range have almost no influence on the albedo diurnal amount. The estimation of radiation were made by linear regression, using the global solar irradiance (Rg) and net short-waves radiation (Rc) as independent variables. All estimates of radiation showed better adjustment for specific phenological periods compared to the entire crop growing cycle. The net radiation in the greenhouse has been estimated by the global solar irradiance measured at field conditions.

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Thermal Storage of Nitrate Salts as Phase Change Materials (PCMs)

Materials ◽

10.3390/ma14237223 ◽

2021 ◽

Vol 14 (23) ◽

pp. 7223

Author(s):

Marco A. Orozco ◽

Karen Acurio ◽

Francis Vásquez-Aza ◽

Javier Martínez-Gómez ◽

Andres Chico-Proano

Keyword(s):

Energy Storage ◽

Phase Change ◽

Sodium Nitrite ◽

Phase Change Materials ◽

Storage Capacity ◽

Thermal Storage ◽

Potassium Nitrate ◽

Ternary Mixtures ◽

Scanning Calorimetry ◽

Nitrate Salts

This study presents the energy storage potential of nitrate salts for specific applications in energy systems that use renewable resources. For this, the thermal, chemical, and morphological characterization of 11 samples of nitrate salts as phase change materials (PCM) was conducted. Specifically, sodium nitrate (NaNO3), sodium nitrite (NaNO2), and potassium nitrate (KNO3) were considered as base materials; and various binary and ternary mixtures were evaluated. For the evaluation of the materials, differential Fourier transform infrared spectroscopy (FTIR), scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) to identify the temperature and enthalpy of phase change, thermal stability, microstructure, and the identification of functional groups were applied. Among the relevant results, sodium nitrite presented the highest phase change enthalpy of 220.7 J/g, and the mixture of 50% NaNO3 and 50% NaNO2 presented an enthalpy of 185.6 J/g with a phase change start and end temperature of 228.4 and 238.6 °C, respectively. This result indicates that sodium nitrite mixtures allow the thermal storage capacity of PCMs to increase. In conclusion, these materials are suitable for medium and high-temperature thermal energy storage systems due to their thermal and chemical stability, and high thermal storage capacity.

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A high energy density azobenzene/graphene hybrid: a nano-templated platform for solar thermal storage

Journal of Materials Chemistry A ◽

10.1039/c5ta01263e ◽

2015 ◽

Vol 3 (22) ◽

pp. 11787-11795 ◽

Cited By ~ 55

Author(s):

Wen Luo ◽

Yiyu Feng ◽

Chen Cao ◽

Man Li ◽

Enzuo Liu ◽

...

Keyword(s):

Energy Density ◽

Storage Capacity ◽

Thermal Storage ◽

High Energy ◽

Solar Thermal ◽

High Energy Density

A high functionalization density and inter-planar bundling interaction remarkably improve both the storage capacity and lifetime of solar thermal fuels using an azobenzene/graphene nano-template.

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