scholarly journals Development and Evaluation of an Improved Apparatus for Measuring the Emissivity at High Temperatures

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6252
Author(s):  
Mariacarla Arduini ◽  
Jochen Manara ◽  
Thomas Stark ◽  
Hans-Peter Ebert ◽  
Jürgen Hartmann
Keyword(s):  
Heat Transfer ◽  
Measurement Procedure ◽  
Heat Transfer Fluid ◽  
Vacuum Vessel ◽  
Heating Unit ◽  
Warm Up ◽  
Measurement Results ◽  
Emissivity Measurement ◽  
Ftir Spectrometer ◽  
Directional Emissivity

An improved apparatus for measuring the spectral directional emissivity in the wavelength range between 1 µm and 20 µm at temperatures up to 2400 K is presented in this paper. As a heating unit an inductor is used to warm up the specimen, as well as the blackbody reference to the specified temperatures. The heating unit is placed in a double-walled vacuum vessel. A defined temperature, as well as a homogenous temperature distribution of the whole surrounding is ensured by a heat transfer fluid flowing through the gap of the double-walled vessel. Additionally, the surrounding is coated with a high-emitting paint and serves as blackbody-like surrounding to ensure defined boundary conditions. For measuring the spectral directional emissivity at different emission angles, a movable mirror is installed in front of the specimen, which can be adjusted by a rotatable arrangement guiding the emitted radiation into the attached FTIR-spectrometer. The setup of the emissivity measurement apparatus (EMMA) and the measurement procedure are introduced, and the derived measurement results are presented. For evaluating the apparatus, measurements were performed on different materials. The determined emissivities agree well with values published in literature within the derived relative uncertainties below 4% for most wavelengths.

Doping Solar Field Heat Transfer Fluid With Nanoparticles

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Mohammad Abutayeh ◽  
Yacine Addad ◽  
Eiyad Abu-Nada ◽  
Anas Alazzam
Keyword(s):  
Heat Transfer ◽  
Power Generation ◽  
Solar Power ◽  
Thermal Power ◽  
Heat Transfer Fluid ◽  
Warm Up ◽  
Different Seasons ◽  
Solar Field ◽  
Thermo Physical Properties ◽  
Solar Thermal Power Generation

A previously developed model of a concentrating solar power plant has been modified to accommodate doping the heat transfer fluid (HTF) with nanoparticles. The model with its unalloyed HTF has been validated with actual operating data beforehand. The thermo-physical properties of the HTF were modified to account for the nanoparticle doping. The nanoparticle content in the HTF was then varied to evaluate its influence on solar power generation. The model was run to simulate plant operation on four different days representing the four different seasons. As the nanoparticle concentration was increased, heat losses were slightly reduced, transient warm up heat was increased, transient cool down heat was reduced, and the overall impact on power generation was trivial. Doping HTFs with nanoparticles does not seem promising for solar thermal power generation from a performance perspective. Moreover, doping HTFs with nanoparticles involves many other operational challenges such as sedimentation and abrasion.

Doping Solar Field Heat Transfer Fluid With Nano–Particles

2017 ◽  
Author(s):  
Mohammad Abutayeh ◽  
Yacine Addad ◽  
Anas Alazzam
Keyword(s):  
Heat Transfer ◽  
Power Generation ◽  
Solar Power ◽  
Thermal Power ◽  
Nano Particles ◽  
Heat Transfer Fluid ◽  
Nano Particle ◽  
Warm Up ◽  
Heat Transfer Fluids ◽  
Different Seasons

A previously–developed model of a concentrating solar power plant has been modified to accommodate doping the heat transfer fluid with nano–particles. The model with its unalloyed heat transfer fluid has been validated with actual operating data beforehand. The thermo–physical properties of the heat transfer fluid were modified to account for the nano–particle doping. The nano–particle content in the heat transfer fluid was then varied to evaluate its influence on solar power generation. The model was run to simulate plant operation on four different days representing the four different seasons. As the nano–particle concentration was increased, heat losses were slightly reduced, transient warm up heat was increased, transient cool down heat was reduced, and the overall impact on power generation was trivial. Doping heat transfer fluids with nano–particles does not seem promising for solar thermal power generation from a performance perspective. Moreover, doping heat transfer fluids with nano–particles involves many other operational challenges such as sedimentation and abrasion.

Experimental Study on Thermal Characteristics of Finned Coil LHSU Using Paraffin as Phase Change Material

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Guansheng Chen ◽  
Nanshuo Li ◽  
Huanhuan Xiang ◽  
Fan Li
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Phase Change ◽  
Phase Change Material ◽  
Water Flow ◽  
Water Flow Rate ◽  
Thermal Characteristics ◽  
Heat Transfer Fluid ◽  
Latent Heat Storage ◽  
Change Material

It is well known that attaching fins on the tubes surfaces can enhance the heat transfer into and out from the phase change materials (PCMs). This paper presents the results of an experimental study on the thermal characteristics of finned coil latent heat storage unit (LHSU) using paraffin as the phase change material (PCM). The paraffin LHSU is a rectangular cube consists of continuous horizontal multibended tubes attached vertical fins at the pitches of 2.5, 5.0, and 7.5 mm that creates the heat transfer surface. The shell side along with the space around the tubes and fins is filled with the material RT54 allocated to store energy of water, which flows inside the tubes as heat transfer fluid (HTF). The measurement is carried out under four different water flow rates: 1.01, 1.30, 1.50, and 1.70 L/min in the charging and discharging process, respectively. The temperature of paraffin and water, charging and discharging wattage, and heat transfer coefficient are plotted in relation to the working time and water flow rate.

scholarly journals Numerical Evaluation of a HVAC System Based on a High-Performance Heat Transfer Fluid

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3298
Author(s):  
Gianpiero Colangelo ◽  
Brenda Raho ◽  
Marco Milanese ◽  
Arturo de Risi
Keyword(s):  
Heat Transfer ◽  
High Performance ◽  
Cooling System ◽  
Electrical Energy ◽  
Simulation Software ◽  
Heat Transfer Fluid ◽  
Hvac System ◽  
Dynamic Simulations ◽  
Heating And Cooling ◽  
The University

Nanofluids have great potential to improve the heat transfer properties of liquids, as demonstrated by recent studies. This paper presents a novel idea of utilizing nanofluid. It analyzes the performance of a HVAC (Heating Ventilation Air Conditioning) system using a high-performance heat transfer fluid (water-glycol nanofluid with nanoparticles of Al2O3), in the university campus of Lecce, Italy. The work describes the dynamic model of the building and its heating and cooling system, realized through the simulation software TRNSYS 17. The use of heat transfer fluid inseminated by nanoparticles in a real HVAC system is an innovative application that is difficult to find in the scientific literature so far. This work focuses on comparing the efficiency of the system working with a traditional water-glycol mixture with the same system that uses Al2O3-nanofluid. The results obtained by means of the dynamic simulations have confirmed what theoretically assumed, indicating the working conditions of the HVAC system that lead to lower operating costs and higher COP and EER, guaranteeing the optimal conditions of thermo-hygrometric comfort inside the building. Finally, the results showed that the use of a nanofluid based on water-glycol mixture and alumina increases the efficiency about 10% and at the same time reduces the electrical energy consumption of the HVAC system.

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 Numerical Simulation of the Impact of the Heat Source Position on Melting of a Nano-Enhanced Phase Change Material

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1425
Author(s):  
Tarek Bouzennada ◽  
Farid Mechighel ◽  
Kaouther Ghachem ◽  
Lioua Kolsi
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Numerical Study ◽  
Melting Rate ◽  
Heat Transfer Fluid ◽  
Commercial Code ◽  
Tube Position ◽  
The Impact ◽  
Change Material

A 2D-symmetric numerical study of a new design of Nano-Enhanced Phase change material (NEPCM)-filled enclosure is presented in this paper. The enclosure is equipped with an inner tube allowing the circulation of the heat transfer fluid (HTF); n-Octadecane is chosen as phase change material (PCM). Comsol-Multiphysics commercial code was used to solve the governing equations. This study has been performed to examine the heat distribution and melting rate under the influence of the inner-tube position and the concentration of the nanoparticles dispersed in the PCM. The inner tube was located at three different vertical positions and the nanoparticle concentration was varied from 0 to 0.06. The results revealed that both heat transfer/melting rates are improved when the inner tube is located at the bottom region of the enclosure and by increasing the concentration of the nanoparticles. The addition of the nanoparticles enhances the heat transfer due to the considerable increase in conductivity. On the other hand, by placing the tube in the bottom area of the enclosure, the liquid PCM gets a wider space, allowing the intensification of the natural convection.

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