scholarly journals Comparison of Properties of Various Heat Storage Fluids used with Evacuated Tube of Solar Water Heater

2014 ◽  
Vol 11 (1) ◽  
pp. 111-115
Author(s):  
Baghdad Science Journal
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Heat Storage ◽  
Power Level ◽  
Heat Transfer Fluid ◽  
Solar Thermal Energy ◽  
Storage Material ◽  
Water Heater ◽  
Evacuated Tube ◽  
Better Than

The aim of this work was to capture solar radiation and convert it into solar thermal energy by using a storage material and the heat transfer fluid like oil and water and comparison between them, we used the evacuated tube as a receiver for solar radiation, The results showed that the oil better than water as storage material and the heat transfer fluid and the effective thermal conductivity material and good for power level, rates and durations of charge and discharge cycles.

Parametric and Thermal Management Optimization of a Steel Slag Based Packed Bed Heat Storage

2015 ◽  
Author(s):  
Iñigo Ortega-Fernández ◽  
Antoni Gil ◽  
Abdessamad Faik ◽  
Javier Rodríguez-Aseguinolaza ◽  
Bruno D’Aguanno
Keyword(s):  
Heat Transfer ◽  
Thermal Management ◽  
Heat Storage ◽  
Fluid Dynamic ◽  
Steel Slag ◽  
Packed Bed ◽  
Heat Transfer Fluid ◽  
Storage Material ◽  
Storage Unit ◽  
Heat Storage Material

In this work steel slag, one of the main by-products of the steelmaking industry, is proposed as a competitive and effective heat storage material. The implemented storage design suggested for this material is a solid packed bed arrangement based in the temperature stratification (thermocline) phenomena. In particular, two different solutions based on different storage tank geometries, cylindrical and conical, have been modeled by using computational fluid dynamic (CFD) methods. In addition, both geometries have been simulated under two different operation modes as a function of the used heat transfer fluid: solar salt and air. This selection permitted to investigate the operation of the proposed storage for current CSP technologies which make use of molten salt as storage/heat transfer fluid and also the analysis of the system when the operation parameters are potentially associated to new generation CSP plants at higher temperatures, above 600 °C. The comparison between the simulated systems has allowed to determine the influence of the driving parameters on the proposed storage solution, such as the operation temperature range, nature of the heat transfer fluid or geometrical implications. The thermal management of the storage unit has also been shown during a transient operation up to a reproducible behavior. Overall, the selected parameters for the presented modeling analysis have revealed the high potential of steel slag as heat storage material and the suitability and flexibility of the implemented packed bed solution.

scholarly journals Experimental Investigation of a Medium Temperature Single-Phase Thermosyphon in an Evacuated Tube Receiver Coupled With Compound Parabolic Concentrator

2021 ◽  
Vol 9 ◽  
Author(s):  
Javed Akhter ◽  
S. I. Gilani ◽  
Hussain H. Al-Kayiem ◽  
Mubbashar Mehmood ◽  
Muzaffar Ali ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Energy ◽  
Single Phase ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Outlet Temperature ◽  
Solar Thermal Energy ◽  
Medium Temperature ◽  
Temperature Range ◽  
Evacuated Tube

The integration of evacuated tube receivers with non-imaging compound parabolic concentrators (CPCs) operating in thermosyphon mode provides the opportunity to deliver solar thermal energy in the medium temperature range that is suitable for many industrial applications. However, the performance of single-phase thermosyphon in the medium temperature range has not been comprehensively investigated. This paper presents the design, development, and performance evaluation of a single-phase thermosyphon in an evacuated tube receiver integrated with a modified CPC solar collector. The thermohydraulic performance of the developed system is evaluated in the tropical climate using Therminol-55 oil as heat transfer fluid. The results demonstrate that the maximum outlet temperature reached over 120°C using thermal oil as heat transfer fluid while it remained at 100°C in case of water. The zero-loss thermal efficiency reached up to 70% on a clear sky day. Comparing the thermal performance of the developed CPC collector with an existing model of a non-concentrating collector showed much improvement at elevated temperatures. This indicates that this system can effectively operate in tropical weather conditions to provide sustainable solar thermal energy in the medium temperature range.

scholarly journals Modification of a Solar Thermal Collector to Promote Heat Transfer inside an Evacuated Tube Solar Thermal Absorber

2021 ◽  
Vol 11 (9) ◽  
pp. 4100
Author(s):  
Rasa Supankanok ◽  
Sukanpirom Sriwong ◽  
Phisan Ponpo ◽  
Wei Wu ◽  
Walairat Chandra-ambhorn ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Small Scale ◽  
Medium Temperature ◽  
Change Behavior ◽  
Set Up ◽  
Evacuated Tube ◽  
Heating Medium

Evacuated-tube solar collector (ETSC) is developed to achieve high heating medium temperature. Heat transfer fluid contained inside a copper heat pipe directly affects the heating medium temperature. A 10 mol% of ethylene-glycol in water is the heat transfer fluid in this system. The purpose of this study is to modify inner structure of the evacuated tube for promoting heat transfer through aluminum fin to the copper heat pipe by inserting stainless-steel scrubbers in the evacuated tube to increase heat conduction surface area. The experiment is set up to measure the temperature of heat transfer fluid at a heat pipe tip which is a heat exchange area between heat transfer fluid and heating medium. The vapor/ liquid equilibrium (VLE) theory is applied to investigate phase change behavior of the heat transfer fluid. Mathematical model validated with 6 experimental results is set up to investigate the performance of ETSC system and evaluate the feasibility of applying the modified ETSC in small-scale industries. The results indicate that the average temperature of heat transfer fluid in a modified tube increased to 160.32 °C which is higher than a standard tube by approximately 22 °C leading to the increase in its efficiency by 34.96%.

scholarly journals Comparative Modeling of a Parabolic Trough Collectors Solar Power Plant with MARS Models

Energies ◽  
2017 ◽  
Vol 11 (1) ◽  
pp. 37 ◽  
Author(s):  
Jose Rogada ◽  
Lourdes Barcia ◽  
Juan Martinez ◽  
Mario Menendez ◽  
Francisco de Cos Juez
Keyword(s):  
Heat Transfer ◽  
Water Vapor ◽  
Power Plant ◽  
Solar Radiation ◽  
Thermal Energy ◽  
Power Plants ◽  
Solar Power ◽  
Rankine Cycle ◽  
Heat Transfer Fluid ◽  
Solar Field

Power plants producing energy through solar fields use a heat transfer fluid that lends itself to be influenced and changed by different variables. In solar power plants, a heat transfer fluid (HTF) is used to transfer the thermal energy of solar radiation through parabolic collectors to a water vapor Rankine cycle. In this way, a turbine is driven that produces electricity when coupled to an electric generator. These plants have a heat transfer system that converts the solar radiation into heat through a HTF, and transfers that thermal energy to the water vapor heat exchangers. The best possible performance in the Rankine cycle, and therefore in the thermal plant, is obtained when the HTF reaches its maximum temperature when leaving the solar field (SF). In addition, it is necessary that the HTF does not exceed its own maximum operating temperature, above which it degrades. The optimum temperature of the HTF is difficult to obtain, since the working conditions of the plant can change abruptly from moment to moment. Guaranteeing that this HTF operates at its optimal temperature to produce electricity through a Rankine cycle is a priority. The oil flowing through the solar field has the disadvantage of having a thermal limit. Therefore, this research focuses on trying to make sure that this fluid comes out of the solar field with the highest possible temperature. Modeling using data mining is revealed as an important tool for forecasting the performance of this kind of power plant. The purpose of this document is to provide a model that can be used to optimize the temperature control of the fluid without interfering with the normal operation of the plant. The results obtained with this model should be necessarily contrasted with those obtained in a real plant. Initially, we compare the PID (proportional–integral–derivative) models used in previous studies for the optimization of this type of plant with modeling using the multivariate adaptive regression splines (MARS) model.

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.

Optimizing an Active Solar still for Sea Water Desalination

2014 ◽  
Vol 1051 ◽  
pp. 985-991
Author(s):  
Osman Ali Hamadou ◽  
Khamlichi Abdellatif
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Sea Water ◽  
Saline Water ◽  
Phase Changes ◽  
Water Desalination ◽  
Heat Transfer Fluid ◽  
Water Yield ◽  
Inlet Temperature ◽  
Glass Cover

Sea water desalination through solar radiation distillation process can achieve low cost and sustainable fresh water for remote dry areas. In conventional passive solar stills, the solar radiation passes through the transparent cover and supplies heat to sea water with limited back reflection. The evaporative heat transfer between the water surface and the glass cover produces the distillate by means of film type condensation at the inner surface of the glass cover. In order to enhance evaporation/condensation phase changes, active solar stills were introduced. In these last, saline water is circulated and put in contact with a heat source which supplies heat to the saline water. With this extra energy, the distillate productivity is increased. In this work, heat supply is assumed to be controlled such that the temperature at the inlet of the still can be adjusted through regulation of the circulating heat transfer fluid rate. Using a modelling based on uniform temperature in each still component, a set of ordinary differential equations was derived. The input variables comprised heat transfer fluid rate, inlet temperature as well as sea water rate and basin depth. Extensive parametric studies were performed after that and optimization of the distilled water yield and rate was discussed.

scholarly journals Modeling and Characteristic Analysis of a Solar Parabolic Trough System: Thermal Oil as the Heat Transfer Fluid

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Zhai Rongrong ◽  
Yang Yongping ◽  
Yan Qin ◽  
Zhu Yong
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Working Condition ◽  
Heat Transfer Fluid ◽  
System Dynamic Model ◽  
Parabolic Trough ◽  
Characteristic Analysis ◽  
Collector System ◽  
Typical Summer ◽  
Thermal Oil

The thermal oil is applied as the heat transfer fluid in a solar parabolic trough collector system. Firstly, the system dynamic model was established and validated by the real operating data in typical summer and spring days in references. Secondly, the alteration characteristics of different solar radiation, inlet water temperature and flow rate, and collectors’ area and length are analyzed and compared with the normal working condition. The model can be used for studying, system designing, and better understanding of the performance of parabolic trough systems.

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