scholarly journals Radiation of Heat in an Insulating Vacuum Layer

2017 ◽  
Vol 69 (1) ◽  
pp. 87-100
Author(s):  
Mária Minárová
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Heat Exchange ◽  
Heat Storage ◽  
Storage System ◽  
Heat Accumulation ◽  
Insulating Layer ◽  
System A ◽  
Set Up ◽  
Heat Transfer By Radiation

Abstract The paper is motivated by the previous research concerning the heat transfer in a heat accumulation device. The device had been explored, built up and tested with the aim of utilization of cheap solar energy and its storage. In this heat storage system, a vacuum-like gap between two concentric containers acts as an insulating layer, radiation being the predominant heat transfer type in the gap. The better knowledge and understanding of the heat exchange by radiation, the more effectiveness of the insulation of the layer can be reached. Heat transfer by radiation is explored in the paper, mathematical model is set up, the algorithm of non-linear transient computation is introduced, and some illustrative results of this computation are performed.

Solid Media Thermal Storage Development and Analysis of Modular Storage Operation Concepts for Parabolic Trough Power Plants

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Doerte Laing ◽  
Wolf-Dieter Steinmann ◽  
Michael Fiß ◽  
Rainer Tamme ◽  
Thomas Brand ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Power Plants ◽  
Heat Storage ◽  
Storage Systems ◽  
Storage System ◽  
Sensible Heat ◽  
Economic Optimization ◽  
Parabolic Trough ◽  
Solid Media ◽  
Exergetic Analysis

Cost-effective integrated storage systems are important components for the accelerated market penetration of solarthermal power plants. Besides extended utilization of the power block, the main benefits of storage systems are improved efficiency of components, and facilitated integration into the electrical grids. For parabolic trough power plants using synthetic oil as the heat transfer medium, the application of solid media sensible heat storage is an attractive option in terms of investment and maintenance costs. For commercial oil trough technology, a solid media sensible heat storage system was developed and tested. One focus of the project was the cost reduction of the heat exchanger; the second focus lies in the energetic and exergetic analysis of modular storage operation concepts, including a cost assessment of these concepts. The results show that technically there are various interesting ways to improve storage performance. However, these efforts do not improve the economical aspect. Therefore, the tube register with straight parallel tubes without additional structures to enhance heat transfer has been identified as the best option concerning manufacturing aspects and investment costs. The results of the energetic and exergetic analysis of modular storage integration and operation concepts show a significant potential for economic optimization. An increase of more than 100% in storage capacity or a reduction of more than a factor of 2 in storage size and therefore investment cost for the storage system was calculated. A complete economical analysis, including the additional costs for this concept on the solar field piping and control, still has to be performed.

scholarly journals Effective Separation of a Water in Oil Emulsion from a Direct Contact Latent Heat Storage System

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2264 ◽  
Author(s):  
Sebastian Ammann ◽  
Andreas Ammann ◽  
Rebecca Ravotti ◽  
Ludger Fischer ◽  
Anastasia Stamatiou ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Latent Heat ◽  
Direct Contact ◽  
Heat Storage ◽  
Storage System ◽  
Heat Transfer Fluid ◽  
Storage Unit ◽  
Latent Heat Storage ◽  
Oil Emulsion ◽  
Water In Oil Emulsion

The problem of emulsification between Phase Change Material (PCM) and Heat Transfer Fluid (HTF) in direct contact latent heat storage systems has been reported in various studies. This issue causes the PCM to flow out of the storage tank and crystallize at unwanted locations and thus presents a major limitation for the proper operation of such systems. These anomalies become more pronounced when high HTF flow rates are employed with the aim to achieve fast heat transfer rates. The goal of this paper is to find a method which will enable the fast separation of the formed emulsion and thus the uninterrupted operation of the storage unit. In this study, three separation methods were examined and the use of superhydrophobic filters was chosen as the best candidate for the demulsification of the PCM and HTF mixtures. The filter was produced by processing of a melamine sponge with different superhydrophobic adhesives and was tested with emulsions closely resembling the ones formed in a real direct contact setup. The superhydrophobic filter obtained, was able to separate the emulsions effectively while presenting a very high permeability (up to 1,194,980 kg h−1 m−2 bar−1). This is the first time the use of a superhydrophobic sponge has been investigated in the context of demulsification in direct contact latent heat storage.

Analysis on unsteady heat transfer and fluid flow through sensible heat storage system

2021 ◽  
Author(s):  
Sasikumar C ◽  
Sundaresan R ◽  
Rajaganapthy C ◽  
Nagaraj M ◽  
Radha Krishnan Beemaraj
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Storage ◽  
Storage System ◽  
Sensible Heat ◽  
Unsteady Heat Transfer ◽  
Flow Through

scholarly journals Optimizing air velocity for the underfloor forced ventilation to protect a refrigerated warehouse from frost heaving

2018 ◽  
Vol 38 (3) ◽  
pp. 321-327
Author(s):  
Jingfu Jia ◽  
Manjin Hao ◽  
Jianhua Zhao
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Frost Heave ◽  
Forced Ventilation ◽  
Air Velocity ◽  
Set Up

Forced or natural ventilation is the most common measure of frost heave protection for refrigerated warehouse floor. To optimize air velocity for the underfloor forced ventilation system of refrigerated warehouse, a steady state three-dimensional mathematical model of heat transfer is set up in this paper. The temperature fields of this system are simulated and calculated by CFD software PHOENICS under different air velocity, 1.5m/s, 2.5m/s or 3.5m/s. The results show that the optimized air velocity is 1.5m/s when the tube spacing is 1.5m.

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