Experimental and Numerical Heat Transfer Analysis of an Air-Based Cavity-Receiver for Solar Trough Concentrators

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
R. Bader ◽  
A. Pedretti ◽  
A. Steinfeld
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Solar Power ◽  
Power Input ◽  
Heat Transfer Analysis ◽  
Heat Transfer Fluid ◽  
Inlet Temperature ◽  
Transfer Model ◽  
Outlet Temperature ◽  
Solar Receiver

We report on the field testing of a 42 m-long full-scale solar receiver prototype installed on a 9 m-aperture solar trough concentrator. The solar receiver consists of a cylindrical cavity containing a tubular absorber with air as the heat transfer fluid (HTF). Experimental results are used to validate a heat transfer model based on Monte Carlo ray-tracing and finite-volume techniques. Performance predictions obtained with the validated model yield the following results for the receiver. At summer solstice solar noon, with HTF inlet temperature of 120 °C and HTF outlet temperature in the range 250–450 °C, the receiver efficiency ranges from 45% to 29% for a solar power input of 280 kW. One third of the solar radiation incident on the receiver is lost by spillage at the aperture and reflection inside the cavity. Other heat losses are due to natural convection (9.9–9.7% of solar power input) and re-radiation (6.1–17.6%) through the cavity aperture and by natural convection from the cavity insulation (5.6–9.1%). The energy penalty associated with the HTF pumping work represents 0.6–24.4% of the power generated.

An Air-Based Cavity-Receiver for Solar Trough Concentrators

2010 ◽  
Author(s):  
Roman Bader ◽  
Maurizio Barbato ◽  
Andrea Pedretti ◽  
Aldo Steinfeld
Keyword(s):  
Heat Transfer ◽  
Solar Power ◽  
Power Input ◽  
Absorption Efficiency ◽  
Conservation Equation ◽  
Heat Transfer Fluid ◽  
Inlet Temperature ◽  
Transfer Model ◽  
Pumping Power ◽  
Power Requirement

A cylindrical cavity-receiver containing a tubular absorber that uses air as the heat transfer fluid is proposed for a novel solar trough concentrator design. A numerical heat transfer model is developed to determine the receiver’s absorption efficiency and pumping power requirement. The 2D steady-state energy conservation equation coupling radiation, convection and conduction heat transfer is formulated and solved numerically by finite-difference techniques. The Monte Carlo ray-tracing and radiosity methods are applied to establish the solar radiation distribution and radiative exchange within the receiver. Simulations were conducted for a 50 m-long and 9.5 m-wide collector section with 120°C air inlet temperature, and air mass flows in the range 0.1–1.2 kg/s. Outlet air temperatures ranged from 260 to 601 °C, and corresponding absorption efficiencies varied between 60 and 18%. Main heat losses integrated over the receiver length were due to reflection and spillage at the receiver’s windowed aperture, amounting to 13% and 9% of the solar power input, respectively. The pressure drop along the 50 m module was in the range 0.23 to 11.84 mbar, resulting in isentropic pumping power requirements of 6.45·10−4%–0.395% of the solar power input.

An Air-Based Cavity-Receiver for Solar Trough Concentrators

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Roman Bader ◽  
Maurizio Barbato ◽  
Andrea Pedretti ◽  
Aldo Steinfeld
Keyword(s):  
Heat Transfer ◽  
Solar Power ◽  
Power Input ◽  
Absorption Efficiency ◽  
Conservation Equation ◽  
Heat Transfer Fluid ◽  
Inlet Temperature ◽  
Transfer Model ◽  
Pumping Power ◽  
Power Requirement

A cylindrical cavity-receiver containing a tubular absorber that uses air as the heat transfer fluid is proposed for a novel solar trough concentrator design. A numerical heat transfer model is developed to determine the receiver’s absorption efficiency and pumping power requirement. The 2D steady-state energy conservation equation coupling radiation, convection, and conduction heat transfer is formulated and solved numerically by finite volume techniques. The Monte Carlo ray-tracing and radiosity methods are applied to establish the solar radiation distribution and radiative exchange within the receiver. Simulations were conducted for a 50 m-long and 9.5 m-wide collector section with 120°C air inlet temperature, and air mass flows in the range 0.1–1.2 kg/s. Outlet air temperatures ranged from 260°C to 601°C, and corresponding absorption efficiencies varied between 60% and 18%. Main heat losses integrated over the receiver length were due to reflection and spillage at the receiver’s windowed aperture, amounting to 13% and 9% of the solar power input, respectively. The pressure drop along the 50 m module was in the range 0.23–11.84 mbars, resulting in isentropic pumping power requirements of 6.45×10−4−0.395% of the solar power input.

Heat Pipe Solar Receivers for Concentrating Solar Power (CSP) Plants

2013 ◽  
Author(s):  
Yiding Cao
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Solar Power ◽  
High Heat ◽  
Solar Flux ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Efficient Operation ◽  
High Heat Transfer ◽  
Solar Receiver

This paper introduces separate-type heat pipe (STHP) based solar receiver systems that enable more efficient operation of concentrated solar power plants without relying on a heat transfer fluid. The solar receiver system may consist of a number of STHP modules that receive concentrated solar flux from a solar collector system, spread the high concentrated solar flux to a low heat flux level, and effectively transfer the received heat to the working fluid of a heat engine to enable a higher working temperature and higher plant efficiency. In general, the introduced STHP solar receiver has characteristics of high heat transfer capacity, high heat transfer coefficient in the evaporator to handle a high concentrated solar flux, non-condensable gas release mechanism, and lower costs. The STHP receiver in a solar plant may also integrate the hot/cold tank based thermal energy storage system without using a heat transfer fluid.

A 50 kW Fluidized Bed High Temperature Solar Receiver: Heat Transfer Analysis

1988 ◽  
Vol 110 (4) ◽  
pp. 313-320 ◽  
Author(s):  
G. Flamant ◽  
D. Gauthier ◽  
C. Boudhari ◽  
Y. Flitris
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Large Diameter ◽  
Pilot Scale ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
Front Wall ◽  
Measured Efficiency ◽  
The Mean ◽  
Solar Receiver

A theoretical and experimental investigation of a pilot scale solar fluidized bed receiver is presented. Large diameter alumina particles were used. Experimental data with the bed in the temperature range of 550° C to 915° C (wall 740° C–1035° C) are compared with a simple model based on one parameter: the mean front wall temperature. At 950° C, the predicted efficiency is 73 percent and the measured efficiency is about 65 percent. In addition, unsteady behavior of the receiver is described by a simple heat transfer model.

scholarly journals Heat Transfer Performance of Fruit Juice in a Heat Exchanger Tube Using Numerical Simulations

2020 ◽  
Vol 10 (2) ◽  
pp. 648
Author(s):  
Juan Ignacio Córcoles ◽  
Ernesto Marín-Alarcón ◽  
Jose Antonio Almendros-Ibáñez
Keyword(s):  
Heat Transfer ◽  
Activation Energy ◽  
Newtonian Fluid ◽  
Food Industry ◽  
Fruit Juice ◽  
Heat Transfer Process ◽  
Heat Transfer Fluid ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
The Difference

Enhancing heat transfer rates in heat exchangers is essential in many applications, such as in the food industry. Most fluids used in the food industry are non-Newtonian, whose viscosity is not uniform, and depends on the shear rate and temperature gradient. This is important in the selection of equipment and type of processing. The aim of this work was to numerically simulate, with a non-Newtonian fluid in laminar regime, the heat transfer process in a tube with a curved elbow. The numerical model was validated with published correlations using water as heat transfer fluid. A commercially available fruit juice was used as a non-Newtonian fluid. Its rheological properties were measured using a Modular Compact Rheometer, as well as the activation energy. The difference between outlet temperature and inlet temperature was higher for the laminar simulation (approximately 4 °C) than for the turbulent one (approximately 0.7 °C). The highest dynamic viscosity values were found at the centre of the pipe (between 0.05 and 0.09 Pa·s), with the lowest values at the wall (0.0076 Pa·s). This behaviour is explained by the pseudoplastic condition of the fruit juice. The activation energy did not yield high values, showing a moderate viscosity variation with the temperature change.

Investigating the effect of using nanofluids on the performance of a double-effect absorption refrigeration cycle combined with a solar collector

2019 ◽  
Vol 234 (7) ◽  
pp. 981-993 ◽  
Author(s):  
Mohamad Aramesh ◽  
Fathollah Pourfayaz ◽  
Mehdi Haghir ◽  
Alibakhsh Kasaeian ◽  
Mohammad H Ahmadi
Keyword(s):  
Heat Transfer ◽  
Ag Nanoparticles ◽  
Pure Water ◽  
Double Effect ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Refrigeration Cycle ◽  
Outlet Temperature ◽  
Absorption Refrigeration

In this article, the performance of a double-effect LiBr-H2O absorption refrigeration cycle is studied and is improved by applying solar energy and utilizing nanofluids. A trough collector is used to preheat the working fluid before entering the generator of the cycle. In addition, four different nanofluids are considered as the heat transfer fluid of the collector: Al2O3, Ag, Cu, and CuO. The effects of using nanofluids on the outlet temperature of the heat transfer fluid, the temperature of the working fluid entering the generator, the heat produced by the generator, and COP of the cycle are studied. Different concentrations of the nanoparticles from 0 to 2.5% are considered for the nanofluids. The results indicate that in all the concentrations, Ag nanoparticles will have a better performance comparing to the other types. Furthermore, it was concluded that the higher concentrations of the nanoparticles and along with it the higher inlet temperature of the generator will decrease the generator heat production rate up to 4%. Moreover, considering the constant cooling capacity of the cycle, usage of the Ag nanoparticles in the concentration of 2.5% increases the value of COP up to 3.9%, with respect to the pure water.

scholarly journals Study on Outlet Temperature Control of External Receiver for Solar Power Tower

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 340
Author(s):  
Qiang Zhang ◽  
Kaijun Jiang ◽  
Yanqiang Kong ◽  
Jiangbo Wu ◽  
Xiaoze Du
Keyword(s):  
Temperature Control ◽  
Control Strategy ◽  
Solar Power ◽  
Heat Transfer Fluid ◽  
Weather Data ◽  
Unstable State ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
Power Load ◽  
Solar Power Tower

Due to the change of direct normal irradiance (DNI) and the change of output power load, the receiver of the solar tower is in an unstable state in the actual operation. In this paper, a 100 MW external cylindric receiver is designed and modelled. The dynamic and comprehensive model is established for the receiver, including the thermal and mechanical equations. The temperature control strategy is applied to the receiver model. The validity of the control strategy is verified by disturbance experiments, including DNI, the inlet temperature of the heat transfer fluid (HTF), and the weather data on a cloudy day. The response characteristics of the receiver are demonstrated. Its thermal lag characteristics and restraining effect on the fluctuating environment are revealed. The dangerous occasion of the receiver during operation are detected, including the overheat of the local panel, and the dissociation point of the molten salt. Both the robustness and the deficiency of the control strategy of the receiver are pointed out. The research results will contribute to the control strategy formulation of the SPT (solar power tower) station.

Conceptual design of porous volumetric solar receiver using molten salt as heat transfer fluid

2021 ◽  
Vol 301 ◽  
pp. 117400
Author(s):  
Shen Du ◽  
Ming-Jia Li ◽  
Ya-Ling He ◽  
Sheng Shen
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
Conceptual Design ◽  
Heat Transfer Fluid ◽  
Solar Receiver
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