scholarly journals Nonuniform Heat Transfer Model and Performance of Molten Salt Cavity Receiver

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1001
Author(s):  
Jianfeng Lu ◽  
Yarong Wang ◽  
Jing Ding
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
Thermal Efficiency ◽  
Radiation Flux ◽  
Incident Radiation ◽  
Heat Transfer Model ◽  
Experimental Result ◽  
Transfer Model ◽  
Fluid Temperature ◽  
Primary Role

The temperature distribution and thermal efficiency of a molten salt cavity receiver are investigated by a nonuniform heat transfer model based on thermal resistance analysis. For the cavity receiver MSEE in Sandia National Laboratories, thermal efficiency in this experiment is about 87.5%, and the calculation value of 86.93–87.79% by a present nonuniform model fits very well with the experimental result. Different from the uniform heat transfer model, the receiver surface temperature in the nonuniform heat transfer model is remarkably higher than the backwall temperature. The incident radiation flux plays a primary role in thermal performance of cavity receiver, and thermal efficiency approaches to maximum under optimal incident radiation flux. In order to increase thermal efficiency, various methods are proposed and studied, including heat convection enhancement by an increase of flow velocity or the decrease of the tube diameter and number of tubes in the panel, and heat loss decline by a decrease of view factor, surface emissivity and insulation conductivity. According to calculation results by different modes of the nonuniform heat transfer model, the thermal efficiency of the cavity receiver is reduced by nonuniform heat transfer caused by variable fluid temperature or variable circumferential temperature, so thermal efficiency calculated by variable fluid temperature and variable circumferential temperature is lower than that calculated by average fluid temperature and bilateral uniform circumferential temperature for 0.86%.

Heat Transfer Modeling of Nanoparticle Packings on a Substrate

2018 ◽  
Author(s):  
Anil Yuksel ◽  
Edward T. Yu ◽  
Michael Cullinan ◽  
Jayathi Murthy
Keyword(s):  
Heat Transfer ◽  
Laser Power ◽  
Thermal Conductance ◽  
Heat Transfer Model ◽  
Experimental Result ◽  
Transfer Model ◽  
Heat Transfer Modeling ◽  
Interfacial Thermal Conductance ◽  
High Laser ◽  
Good Agreement

The temperature evolution of nanoparticle packings on a substrate under high laser power is investigated both experimentally and via numerical simulations. Numerical modeling of temperature distributions in copper nanoparticle packings on a glass substrate is performed and results are compared with experiment under 2.6 kW/cm2 laser power. A coupled electromagnetic-heat transfer model is implemented to understand the nanoparticle temperature distribution. Very good agreement between the coupled electromagnetic-heat transfer model and the experimental results is obtained by matching the interfacial thermal conductance, G, between the nanoparticles using the experimental result in the coupled electromagnetic-heat transfer model.

Heat Efficiency of Trough Solar Vacuum Receiver

2014 ◽  
Vol 521 ◽  
pp. 23-27
Author(s):  
Jun Ming Liang ◽  
Jian Feng Lu ◽  
Jing Ding ◽  
Jian Ping Yang
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Heat Loss ◽  
Wall Temperature ◽  
Radiation Flux ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Parabolic Trough ◽  
Heat Efficiency ◽  
Solar Radiation Flux

The heat loss and thermal performance of solar parabolic trough vacuum receiver were experimentally measured and analyzed by heat transfer model. According to the present experiments, the heat loss of solar parabolic trough vacuum receiver has good agreement with the heat loss of vacuum receiver from Solel company. As the wall temperature increase from 108°C to 158°C, the heat loss of solar parabolic trough vacuum receiver remarkably increases from 35 Wm-2to 57 Wm-2. The heat transfer model of parabolic trough solar receiver is then theoretically investigated due to the energy balances between the heat transfer fluid, absorber tube, glass envelope and surroundings. When solar radiation flux is constant, the heat efficiency of solar parabolic trough system decreases with the wall temperature and oil temperature. When solar radiation flux or solar concentration ratio increases, the heat efficiency of solar parabolic trough system increases.

Joule-Thomson Effect on Heat Transfer in CO2 Injection Wellbore

2013 ◽  
Vol 734-737 ◽  
pp. 1411-1414
Author(s):  
Yi Zhang ◽  
Cheng Hu ◽  
Yong Chen Song
Keyword(s):  
Heat Transfer ◽  
Fluid Pressure ◽  
Pressure Rise ◽  
Injection Pressure ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Fluid Temperature ◽  
Thomson Effect ◽  
Injection Temperature ◽  
Thomson Coefficient

Ramey model is a classical wellbore heat transfer model. However Ramey model did not consider Joule-Thomson effect. In this paper, Ramey model is improved by considering Joule-Thomson effect. The results show that Joule-Thomson effect will cause fluid temperature higher due to a positive Joule-Thomson coefficient and pressure rise. Injection temperature has little effect on fluid temperature. Fluid pressure is influenced by fluid viscidity. Higher injection pressure leads to faster pressure increasing speed.

Solving Military Vehicle Transient Heat Load Issues Using Phase Change Materials

2015 ◽  
Author(s):  
Johnathon P. Putrus ◽  
Stanley T. Jones ◽  
Badih A. Jawad ◽  
Giscard Kfoury ◽  
Selin Arslan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Phase Change Materials ◽  
Cooling System ◽  
Heat Transfer Model ◽  
Heat Of Fusion ◽  
Transfer Model ◽  
Fluid Temperature ◽  
Tractive Effort

Thermal management systems (TMS) of armored ground vehicle designs are often incapable of sustained heat rejection during high tractive effort conditions and ambient conditions. Latent heat energy storage systems that utilize Phase Change Materials (PCMs) present an effective way of storing thermal energy and offer key advantages such as high-energy storage density, high heat of fusion values, and greater stability in temperature control. Military vehicles frequently undergo high-transient thermal loads and often do not provide adequate cooling for powertrain subsystems. This work outlines an approach to temporarily store excess heat generated by the transmission during high tractive effort situations through the use of a passive PCM retrofit thereby extending the operating time, reducing temperature transients, and limiting overheating. A numerical heat transfer model has been developed based on a conceptual vehicle transmission TMS. The model predicts the transmission fluid temperature response with and without a PCM retrofit. The developed model captures the physics of the phase change processes to predict the transient heat absorption and rejection processes. It will be used to evaluate the effectiveness of proposed candidate implementations and provide input for TMS evaluations. Parametric studies of the heat transfer model have been conducted to establish desirable structural morphologies and PCM thermophysical properties. Key parameters include surface structural characteristics, conduction enhancing material, surface area, and PCM properties such as melt temperature, heat of fusion, and thermal conductivity. To demonstrate proof-of-concept, a passive PCM enclosure has been designed to be integrated between a transmission bell housing and torque converter. This PCM-augmented module will temporarily strategically absorb and release heat from the system at a controlled rate. This allows surging fluid temperatures to be clamped below the maximum effective fluid temperature rating thereby increasing component life, reliability, and performance. This work outlines cooling system boundary conditions, mobility/thermal loads, model details, enclosure design characteristics, potential PCM candidates, design considerations, performance data, cooling system impacts, conclusions, and potential future work.

Theoretical Post-Dryout Heat Transfer Model

2018 ◽  
Vol 1 (1) ◽  
pp. 142-150
Author(s):  
Murat Tunc ◽  
Ayse Nur Esen ◽  
Doruk Sen ◽  
Ahmet Karakas
Keyword(s):  
Heat Transfer ◽  
Droplet Diameter ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Operating Pressure ◽  
Vertical Pipe ◽  
Two Phase ◽  
Experimental Values ◽  
Reactor Operating ◽  
Coolant System

A theoretical post-dryout heat transfer model is developed for two-phase dispersed flow, one-dimensional vertical pipe in a post-CHF regime. Because of the presence of average droplet diameter lower bound in a two-phase sparse flow. Droplet diameter is also calculated. Obtained results are compared with experimental values. Experimental data is used two-phase flow steam-water in VVER-1200, reactor coolant system, reactor operating pressure is 16.2 MPa. On heater rod surface, dryout was detected as a result of jumping increase of the heater rod surface temperature. Results obtained display lower droplet dimensions than the experimentally obtained values.

An Engine Heat Transfer Model for Comprehensive Thermal Simulations

2006 ◽  
Author(s):  
Filip Kitanoski ◽  
Wolfgang Puntigam ◽  
Martin Kozek ◽  
Josef Hager
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Thermal Simulations

Developing a CFD heat transfer model for applying high expansion foam in an LNG spill

2021 ◽  
Vol 71 ◽  
pp. 104456
Author(s):  
Zhuoran Zhang ◽  
Pratik Krishnan ◽  
Zeren Jiao ◽  
M. Sam Mannan ◽  
Qingsheng Wang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Expansion Foam
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