Modelling and experimental study of latent heat thermal energy storage with encapsulated PCMs for solar thermal applications

Raul, Appasaheb; Jain, Mohit; Gaikwad, S.D.; Saha, Sandip K.

doi:10.1016/j.applthermaleng.2018.07.123

Cited by 124 publications

(36 citation statements)

References 53 publications

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“…In the single-layered PBTES, the capsule diameter and thickness are 34 and 2 mm ( Figure 4A), whereas in the two-layered PBTES, the capsule diameters are 30 and 20 mm with the capsule thickness of 2 mm ( Figure 4B). It can be observed that in the case of two-layered PBTES (Figure 3B), the PCM in the smaller capsule diameter at (13) to (15). Initially, the outlet temperature of HTF rises rapidly as the sensible heat transfer occurs between the solid PCM and the HTF.…”

Section: Validationmentioning

confidence: 97%

“…Over the past decade, comprehensive research work has been conducted on the packed bed latent heat thermal energy storage system (PBTES) employing spherical PCM capsules having the same diameter to examine the thermal performance by estimating the charging time and the first law efficiency . Xu et al provided an elaborate review of PCM along with thermal performance enhancement techniques suitable for TES for CSP plants.…”

Section: Introductionmentioning

confidence: 99%

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Exergetic and performance analyses of two‐layered packed bed latent heat thermal energy storage system

Saha

Das

2019

Int J Energy Res

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Summary In concentrating solar power (CSP) plant, a novel method involving the use of thermocline can be employed to augment the capability of the thermal energy storage system (TES). The rate of thermocline degradation can be reduced by packing encapsulated phase change material (PCM) in the TES. The thermal performance of the packed bed latent heat thermal energy storage system (PBTES) can be further enhanced by employing different diameters of PCM capsules arranged in multiple layers. In this paper, the thermal and exergetic performance of single‐layered and two‐layered PBTES is evaluated for varying mass flow rate, PCM capsule diameter and bed height of larger PCM capsules using a dynamic model based on simplified energy balance equations for PCM and heat transfer fluid (HTF). The single‐layered PBTES has a lower TES latent charging rate than the two‐layered PBTES. The charging efficiency and charging time of two‐layered PBTES are increased by 15.85% and 16.85%, respectively for reducing the HTF mass flow rate by 14.29%. A higher stratification number can be achieved by using a two‐layered PBTES instead of a single‐layered PBTES filled with the corresponding larger diameter PCM capsules. The second law efficiency of the two‐layered PBTES is found to be less than that of the single‐layered PBTES. A decrease in the bed height of larger PCM capsules decreases the exergetic efficiency of the two‐layered PBTES by 3.27%. The findings from this study can be used in further designing and optimising the multi‐layered PBTES.

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Section: Validationmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Exergetic and performance analyses of two‐layered packed bed latent heat thermal energy storage system

Saha

Das

2019

Int J Energy Res

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“…Raul et al conducted the numerical and experimental studies for evaluating the thermal characteristics of PCM and HTF. The authors evaluated the performance of the system under varying flow rates.…”

Section: Introductionmentioning

confidence: 99%

“…32 Paraffin is the most preferred storage media from all the PCMs because it exhibits high latent fusion energy, a wide range of temperatures, negligible supercoiling, chemically stable and easily available at a lower cost relative to other PCMs. [33][34][35][36] Raul et al 37 conducted the numerical and experimental studies for evaluating the thermal characteristics of PCM and HTF. The authors evaluated the performance of the system under varying flow rates.…”

Section: Introductionmentioning

confidence: 99%

Thermal performance of sensible and latent heat thermal energy storage systems

Suresh

Saini

2020

Int J Energy Res

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Summary The thermal energy storage is an essential subsystem for solar thermal energy systems. Few experimental studies are available to compare the performance of sensible and latent thermal energy storage systems for the same storage configurations. The comparison can provide guidance in selecting the storage system for particular solar thermal applications. The present work focuses on the experimental investigation of sensible and latent thermal storage systems with different mass flow rates. Concrete spheres and paraffin‐encapsulated metal capsules having a uniform diameter of 38 mm were taken as the packing elements and air as a heat transfer fluid for both the storage systems. The performance characteristics of both the storage systems have been evaluated in terms of charging time, instantaneous/cumulative energy absorption and energy storage under different flow rate conditions. Thermal mass, conductivity and flow rate has a substantial impact on temperature difference in the storage system. The charging time and energy storage capacity of the sensible thermal storage system was found to be lesser than the latent thermal storage system for all the flow rates. Based on the study, it is recommended that the latent thermal storage system is preferable for higher energy storage capacity, while for better charging and medium storage capacities sensible storage may be a good option.

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“…Some studies mainly focused on the use of thermal storage systems in solar thermal energy generation systems. Raul et al [6] conducted experiments on a single spherical capsule and a lab-scale setup to investigate melting, and analyzed the effect of capsule diameter and porosity on the LHTES (based latent heat thermal energy storage). The results showed that the energy stored and extraction are faster for a smaller capsule diameter and higher porosity.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Dispatching Electricity Market with Consideration of a Solar-Assisted Coal-Fired Power Generation System

Zhai

Feng

et al. 2019

Energies

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This study investigates the multi-objective optimization of load dispatch of a solar-assisted coal-fired power generation system. The improved environmental/economic load dispatch model considers coal consumption, NO x emissions, and power purchase cost. The singular weighted method is utilized to solve this multi-objective and multi-constraint optimization problem. A power system that includes five power generators, one of which is retrofitted to a solar-assisted coal-fired unit, is also analyzed. It can be concluded that the loads of solar-assisted coal-fired units are higher than the original coal-fired unit, and with the increase of solar radiation, the gap between the loads of two units also increases. In addition, after retrofitting, the coal consumption, the NO x emission, and power costs of units reduce by about 2.05%, 0.45%, and 0.14%, respectively. From the study on the on-grid power tariff, where the tariff drops from 16.29 cents/kWh to 3.26 cents/kWh, NO x emissions drop from 12.31 t to 11.28 t per day, a reduction of about 8.38%. The cost of purchasing electricity decreases from $ 2,982,161.8 to $ 2,020,505.0 per day, a decrease of 32.25%. Therefore, when both coal-fired units and solar-assisted coal-fired units exist in a region, the use of solar-assisted coal-fired power generation units should be prioritized.Energies 2019, 12, 1284 2 of 16 157(2) When the temperature of the feed water out of the oil-water heat exchanger is lower than 158 that of the original second heater but higher than that of the original third heater. The feed water 159 enters the second heater. This mode is shown in (b) position. 160(3) When the temperature of feed water out of the oil-water heat exchanger is lower than that of 161 the original first heater but higher than that of the original second heater. The feed water enters the 162 first heater. This mode is shown in (c) position. 163(4) When the temperature of feed water out of the oil-water heat exchanger is higher than that 164 of the original first heater. The feed water enters the boiler. This mode is shown in (d) position.165 3. Methodology 166Under certain constraints, multi-objective optimization aims to have more than one goal to 167 achieve an optimal solution. One of the easiest ways to obtain the optimal solution is called standard 168 quantization or the singular weighted method. A weight is assigned to each target. All the targets 169 with their own weights are positioned together, and then the problem is solved under the same 170 constraints of the original problem. The obtained solution is a solution to the original problem (called 171 the Pareto solution). The weight arrangement is constantly changed; hence, different optimal

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Modelling and experimental study of latent heat thermal energy storage with encapsulated PCMs for solar thermal applications

Cited by 124 publications

References 53 publications

Exergetic and performance analyses of two‐layered packed bed latent heat thermal energy storage system

Exergetic and performance analyses of two‐layered packed bed latent heat thermal energy storage system

Thermal performance of sensible and latent heat thermal energy storage systems

Optimization of Dispatching Electricity Market with Consideration of a Solar-Assisted Coal-Fired Power Generation System

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