scholarly journals Design Optimization of a Hybrid Steam-PCM Thermal Energy Storage for Industrial Applications

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 898 ◽  
Author(s):  
René Hofmann ◽  
Sabrina Dusek ◽  
Stephan Gruber ◽  
Gerwin Drexler-Schmid

The efficiency of industrial processes can be increased by balancing steam production and consumption with a Ruths steam storage system. The capacity of this storage type depends strongly on the volume; therefore, a hybrid storage concept was developed, which combines a Ruths steam storage with phase change material. The high storage capacity of phase change material can be very advantageous, but the low thermal conductivity of this material is a limiting factor. On the contrary, Ruths steam storages have fast reaction times, meaning that the hybrid storage concept should make use of the advantages and compensate for the disadvantages of both storage types. To answer the question on whether this hybrid storage concept is economically feasible, a non-linear design optimization tool for a hybrid storage system is presented. From a preliminary approximation, the results show that the costs of hybrid storage can be reduced, in comparison to a Ruths steam storage with the same storage capacity. Furthermore, a possible hybrid storage design for a real industrial implementation is discussed. Based on further analyses, it was shown that under certain conditions, the retrofitting of a conventional Ruths steam storage to a hybrid storage can be advantageous and cost-effective, compared to an additional Ruths steam storage.

2018 ◽  
Vol 22 (5) ◽  
pp. 2235-2242 ◽  
Author(s):  
Sabrina Dusek ◽  
Rene Hofmann

The efficiency of many industrial processes, applying steam as heat transfer medium, can be increased by integrating Ruths steam accumulator. This component makes it possible to store surplus steam for consumption at later time, whereby high loading and unloading rates can be realized with this storage type. For improving this storage type in terms of storage capacity and application range a hybrid storage approach is presented. The concept combines a Ruths steam storage with phase change material and electrical heating elements. For a first analysis of the interaction between the Ruths steam accumulator and the phase change material, which surrounds the steam storage vessel, a dynamic model was created. Also, an example which consist of a charging, storing, and discharging phase is presented. The simulation results show a positive impact in terms of storage capacity. Therefore, the hybrid storage concept is a promising approach for integration in industrial processes.


Author(s):  
Tonny Tabassum Mainul Hasan ◽  
Latifa Begum

This study reports on the unsteady two-dimensional numerical investigations of melting of a paraffin wax (phase change material, PCM) which melts over a temperature range of 8.7oC. The PCM is placed inside a circular concentric horizontal-finned annulus for the storage of thermal energy. The inner tube is fitted with three radially diverging longitudinal fins strategically placed near the bottom part of the annulus to accelerate the melting process there. The developed CFD code used in Tabassum et al., 2018 is extended to incorporate the presence of fins. The numerical results show that the average Nusselt number over the inner tube surface, the total melt fraction, the total stored energy all increased at every time instant in the finned annulus compared to the annulus without fins. This is due to the fact that in the finned annulus, the fins at the lower part of the annulus promotes buoyancy-driven convection as opposed to the slow conduction melting that prevails at the bottom part of the plain annulus. Fins with two different heights have been considered. It is found that by extending the height of the fin to 50% of the annular gap about 33.05% more energy could be stored compared to the bare annulus at the melting time of 82.37 min for the identical operating conditions. The effects of fins with different heights on the temperature and streamfunction distributions are found to be different. The present study can provide some useful guidelines for achieving a better thermal energy storage system.


Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1619
Author(s):  
Mohammad Ghalambaz ◽  
Hayder I. Mohammed ◽  
Jasim M. Mahdi ◽  
Amir Hossein Eisapour ◽  
Obai Younis ◽  
...  

A twisted-fin array as an innovative structure for intensifying the charging response of a phase-change material (PCM) within a shell-and-tube storage system is introduced in this work. A three-dimensional model describing the thermal management with charging phase change process in PCM was developed and numerically analyzed by the enthalpy-porosity method using commercial CFD software. Efficacy of the proposed structure of fins for performing better heat communication between the active heating surface and the adjacent layers of PCM was verified via comparing with conventional longitudinal fins within the same design limitations of fin material and volume usage. Optimization of the fin geometric parameters including the pitch, number, thickness, and the height of the twisted fins for superior performance of the proposed fin structure, was also introduced via the Taguchi method. The results show that a faster charging rate, higher storage rate, and better uniformity in temperature distribution could be achieved in the PCMs with Twisted fins. Based on the design of twisted fins, it was found that the energy charging time could be reduced by up to 42%, and the energy storage rate could be enhanced up to 63% compared to the reference case of straight longitudinal fins within the same PCM mass limitations.


Author(s):  
Dominic Groulx ◽  
Wilson Ogoh

One way of storing thermal energy is through the use of latent heat energy storage systems. One such system, composed of a cylindrical container filled with paraffin wax, through which a copper pipe carrying hot water is inserted, is presented in this paper. It is shown that the physical processes encountered in the flow of water, the heat transfer by conduction and convection, and the phase change behavior of the phase change material can be modeled numerically using the finite element method. Only charging (melting) is treated in this paper. The appearance and the behavior of the melting front can be simulated by modifying the specific heat of the PCM to account for the increased amount of energy, in the form of latent heat of fusion, needed to melt the PCM over its melting temperature range. The effects of adding fins to the system are also studied, as well as the effects of the water inlet velocity.


2021 ◽  
Vol 16 (1) ◽  
pp. 032-041
Author(s):  
Pradeep N ◽  
Somesh Subramanian S

Thermal energy storage through phase change material has been used for wide applications in the field of air conditioning and refrigeration. The specific use of this thermal storage has been for energy storage during low demand and release of this energy during peak loads with potential to provide energy savings due to this. The principle of latent heat storage using phase change materials (PCMs) can be incorporated into a thermal storage system suitable for using deep freezers. The evaporator is covered with another box which has storage capacity or passage through phase change material. The results revealed that the performance is increased from 3.2 to 3.5 by using PCM.


Sign in / Sign up

Export Citation Format

Share Document