scholarly journals Thermo-convective Study of a Shell and Tube Thermal Energy Storage Unit

Author(s):  
Abderrahmane Elmeriah ◽  
Driss Nehari ◽  
Mohamed Aichouni

In this paper, we have studied numerically thermo-convective characteristics between a heat transfer fluid (HTF) and phase change material (PCM) in shell and tube thermal energy storage (TES) unit. The paraffin wax is considered as a PCM, filled in a shell which is thermally isolated with the external environment, while the water plays a role of a HTF and flows inside the tube at the moment of charging and discharging cycle. The heat transfer between HTF and PCM is performed by conduction and forced convection, this transfer allows to change the physical state of PCM solid-liquid to obtain a quantity of storable heat in order to create a thermal battery. Enthalpy formulation is used to analyze the heat transfer during melting and solidification process. A good agreement was found between our numerical predictions and the results of the literature. On the other hand, we have investigated the effect of geometrical parameters (tube length and shell diameter) and Reynolds number on the charging and discharging cycles. The obtained results reveal that the tube length and the shell diameter are the most influential parameters on the time of storage system. Similarly, the Reynolds number has much impact on the HTF outlet temperature and the time of solidification and melting process. Furthermore, we have proposed a new thermal storage unit containing the Paraffin wax and RT60 that it gives us a good rate and time of storage compared to the first unit that has only the paraffin wax.

2016 ◽  
Vol 64 (2) ◽  
pp. 401-408
Author(s):  
J. Karwacki ◽  
K. Bogucka-Bykuć ◽  
W. Włosiński ◽  
S. Bykuć

Abstract This paper presents an experimental study performed with the general aim of defining procedures for calculation and optimization of shell-and-tube latent thermal energy storage unit with metals or metal alloys as PCMs. The experimental study is focused on receiving the exact information about heat transfer between heat transfer fluid (HTF) and phase change material (PCM) during energy accumulation process. Therefore, simple geometry of heat transfer area was selected. Two configurations of shell-and-tube thermal energy storage (TES) units were investigated. The paper also highlights the emerging trend (reflected in the literature) with respect to the investigation of metal PCM-based heat storage units in recent years and shortly presents unique properties and application features of this relatively new class of PCMs.


2016 ◽  
Author(s):  
Mitchell Shinn ◽  
Karthik Nithyanandam ◽  
Amey Barde ◽  
Richard Wirz

Currently, concentrated solar power (CSP) plants utilize thermal energy storage (TES) in order to store excess energy so that it can later be dispatched during periods of intermittency or during times of high energy demand. Elemental sulfur is a promising candidate storage fluid for high temperature TES systems due to its high thermal mass, moderate vapor pressure, high thermal stability, and low cost. The objective of this paper is to investigate the behavior of encapsulated sulfur in a shell and tube configuration. An experimentally validated, transient, two-dimensional numerical model of the shell and tube TES system is presented. Initial results from both experimental and numerical analysis show high heat transfer performance of sulfur. The numerical model is then used to analyze the dynamic response of the elemental sulfur based TES system for multiple charging and discharging cycles. A sensitivity analysis is performed to analyze the effect of geometry (system length), cutoff temperature, and heat transfer fluid on the overall utilization of energy stored within this system. Overall, this paper demonstrates a systematic parametric study of a novel low cost, high performance TES system based on elemental sulfur as the storage fluid that can be utilized for different high temperature applications.


2015 ◽  
Vol 766-767 ◽  
pp. 457-462 ◽  
Author(s):  
N. Beemkumar ◽  
A. Karthikeyan

An experimental study is conducted to investigate heat transfer enhancement in Thermal Energy Storage system (TES) with paraffin wax as a Phase Change Material (PCM). Therminol 66 is used as a heat transfer fluid (HTF) to carry the heat throughout circuit. The PCM is encapsulated in spherical shells which is stored in the storage tank. The work includes study of heat transfer rates between HTF and PCM with different encapsulation materials namely Copper, Aluminium and Brass. A series of experiments were conducted to investigate the time required and heat transfer rates of HTF during the processes of charging and discharging of the PCM. Experimentally, Copper was found to have the maximum heat transfer rate and Brass was found to have the least cost/kW of energy stored. In discharging process, the cumulative heat gained by HTF from the brass encapsulated PCM is higher (1419.8 kJ) than aluminium (1199.96 kJ) and copper (815.24 kJ). Thus it can be concluded the brass is the most economical encapsulating material for enhancing the heat transfer in a thermal storage system than copper. The heat transfer from the HTF to PCM occurs in copper are 4.9% faster when compared to Brass and 2.3% faster than Aluminum encapsulation. On the other hand, The cost per kW energy transfer from the different encapsulated materials proves that the brass is cost effective during both charging and discharging process.


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