Development of high temperature phase-change-material storages

Laing, Doerte; Bauer, Thomas; Breidenbach, Nils; Hachmann, Bernd; Johnson, Maike

doi:10.1016/j.apenergy.2012.11.063

Cited by 142 publications

(64 citation statements)

References 10 publications

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“…Though, this cost estimation was useful to compare the feasibility of the three selected alloys. The analysis was also done for NaNO 3 and Mg 49 Zn 51 as PCM for comparison. Results are shown in Table 4 …”

Section: Resultsmentioning

confidence: 99%

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Novel metallic alloys as phase change materials for heat storage in direct steam generation applications

Nieto-Maestre

Iparraguirre-Torres

Velasco

et al. 2016

AIP Conference Proceedings

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Abstract. Concentrating Solar Power (CSP) is one of the key electricity production renewable energy technologies with a clear distinguishing advantage: the possibility to store the heat generated during the sunny periods, turning it into a dispatchable technology. Current CSP Plants use an intermediate Heat Transfer Fluid (HTF), thermal oil or inorganic salt, to transfer heat from the Solar Field (SF) either to the heat exchanger (HX) unit to produce high pressure steam that can be leaded to a turbine for electricity production, or to the Thermal Energy Storage (TES) system. In recent years, a novel CSP technology is attracting great interest: Direct Steam Generation (DSG). The direct use of water/steam as HTF would lead to lower investment costs for CSP Plants by the suppression of the HX unit. Moreover, water is more environmentally friendly than thermal oils or salts, not flammable and compatible with container materials (pipes, tanks). However, this technology also has some important challenges, being one of the major the need for optimized TES systems. In DSG, from the exergy point of view, optimized TES systems based on two sensible heat TES systems (for preheating of water and superheating vapour) and a latent heat TES system for the evaporation of water (around the 70% of energy) is the preferred solution. This concept has been extensively tested [1, 2, 3] using mainly NaNO 3 as latent heat storage medium. Its interesting melting temperature (T m ) of 306ºC, considering a driving temperature difference of 10ºC, means TES charging steam conditions of 107 bar at 316ºC and discharging conditions of 81bar at 296ºC. The average value for the heat of fusion (ΔH f ) of NaNO 3 from literature data is 178 J/g [4]. The main disadvantage of inorganic salts is their very low thermal conductivity (0.5 W/m.K) requiring sophisticated heat exchanging designs. The use of high thermal conductivity eutectic metal alloys has been recently proposed [5,6,7] as a feasible alternative. T m s of these proposed eutectic alloys are too high for currently available DSG solar fields, for instance the Mg 49 -Zn 51 alloy melts at 342ºC requiring saturated steam pressures above 160 bar to charge the TES unit. Being aware of this, novel eutectic metallic alloys have been designed reducing the T m s to the range between 285ºC and 330ºC (79bar and 145bar of charging steam pressure respectively) with ΔH f s between 150 and 170 J/g, and thus achieving metallic Phase Change Materials (PCM) suitable for the available DSG technologies.

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Section: Resultsmentioning

confidence: 99%

“…Inorganic salts as sodium nitrate (melts at 306ºC) ( [1], [2], [3]) and metallic alloys as Mg 49 Zn 51 (melts at 342ºC) ( [5], [6], [7]) have been extensively studied. Suitable PCMs for DSG should have a phase transition temperature about 10ºC below the produced vapour temperature in the SF.…”

Section: Introductionmentioning

confidence: 99%

Novel metallic alloys as phase change materials for heat storage in direct steam generation applications

Nieto-Maestre

Iparraguirre-Torres

Velasco

et al. 2016

AIP Conference Proceedings

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“…However, the most discussed storage materials for LHTES are salts and their eutectics. These materials are characterized by the low heat conductivity [2][3][4]. A widely used method to overcome this heat transport limitation in LHTES is to increase the specific surface of the heat exchanger tubes.…”

Section: Introductionmentioning

confidence: 99%

Transient Numerical Simulation of the Melting and Solidification Behavior of NaNO3 Using a Wire Matrix for Enhancing the Heat Transfer

2016

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Abstract:The paper presents the results of a transient numerical investigation of the melting and solidification process of sodium nitrate (NaNO 3 ), which is used as phase change material. For enhancing the heat transfer to the sodium nitrate an aluminum wire matrix is used. The numerical simulation of the melting and solidification process was done with the enthalpy-porosity approach. The numerical analysis of the melting process has shown that apart from the first period of the charging process, where heat conduction is the main heat transfer mechanism, natural convection is the dominant heat transfer mechanism. The numerical investigation of the solidification process has shown that the dominant heat transfer mechanism is heat conduction. Based on the numerical results, the discharging process has been slower than the charging process. The performance of the charged and discharged power has shown that the wire matrix is an alternative method to enhance the heat transfer into the phase change material.

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“…This storage system was designed to produce higher steam parameters and therefore result in a better cycle efficiency in the power block and therefore lower electricity generating costs, as compared to systems using thermal oil as the heat transfer fluid. For the production of saturated steam, PCM storages for storing energy from pressurized steam up to 350 °C and 150 bar have been studied, developed and tested [4][5][6]. For this maximum temperature, a viable option for coping with the very low thermal conductivities of the phase change materials is to increase the heat transfer area with aluminum fins.…”

Section: Introductionmentioning

confidence: 99%

Experimental analysis of the performance of optimized fin structures in a latent heat energy storage test rig

Johnson¹,

Hübner²,

Reichmann³

et al. 2017

AIP Conference Proceedings

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Numerical analysis of fluid flow and heat transfer during melting inside a cylindrical container for thermal energy storage system AIP Conference Proceedings 1850, 080006 (2017) Abstract. Energy storage systems are a key technology for developing a more sustainable energy supply system and lowering overall CO 2 emissions. Among the variety of storage technologies, high temperature phase change material (PCM) storage is a promising option with a wide range of applications. PCM storages using an extended finned tube storage concept have been designed and techno-economically optimized for solar thermal power plant operations. These finned tube components were experimentally tested in order to validate the optimized design and simulation models used. Analysis of the charging and discharging characteristics of the storage at the pilot scale gives insight into the heat distribution both axially as well as radially in the storage material, thereby allowing for a realistic validation of the design. The design was optimized for discharging of the storage, as this is the more critical operation mode in power plant applications. The data show good agreement between the model and the experiments for discharging.

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Development of high temperature phase-change-material storages

Cited by 142 publications

References 10 publications

Novel metallic alloys as phase change materials for heat storage in direct steam generation applications

Novel metallic alloys as phase change materials for heat storage in direct steam generation applications

Transient Numerical Simulation of the Melting and Solidification Behavior of NaNO3 Using a Wire Matrix for Enhancing the Heat Transfer

Experimental analysis of the performance of optimized fin structures in a latent heat energy storage test rig

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