scholarly journals Optimizing solar dish performance using analytical flux distribution in focal region

2020 ◽  
Vol 9 (1) ◽  
pp. 63-67
Author(s):  
Dany Iman Santoso ◽  
Bambang Antoko ◽  
Djatmiko Ichsani
Keyword(s):  
Heat Loss ◽  
Thermal Efficiency ◽  
Flux Distribution ◽  
Radiative Heat ◽  
Total Heat ◽  
Focal Region ◽  
Radiative Heat Loss ◽  
Total Heat Loss ◽  
Image Characteristics ◽  
Parabolic Dish

In this paper, thermal performance analysis of 4 m2 solar dish collector is presented.The focal image characteristics of the solar dish are determined to propose the suitable design of a receiver. A flat plate was used for the receiver to measure flux distribution in the focal region. The measurement had been done in the midday. Intercept factor based on this distribution had been calculated and was obtained to calculate thermal efficiency after total heat loss was described. From the experiment, total heat loss was formed by conductive and radiative in the receiver. The results showed that the increase in total heat loss followed the increase in receiver temperature and it caused a decrease in thermal efficiency. On the peak of the measurement or in midday, receiver temperature can achieve 138°C and it gave around 1200-Watt heat loss and it was dominated by radiative heat loss for around 80%. The thermal efficiency of the system due to flux distribution measurement in the focal region was above 70% and it was classified as high average but we needed to cover this flux up so it did not lose a lot of heat. Cavity aperture would keep around 20% total heat loss and it minimized radiative heat loss from the flux. The design of cavity aperture was the next discussion to insulate thermal heat reflection of the parabolic dish system from high radiative heat loss.©2020. CBIORE-IJRED. All rights reserved

scholarly journals Effects of Absorber Emissivity on Thermal Performance of a Solar Cavity Receiver

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Jiabin Fang ◽  
Nan Tu ◽  
Jinjia Wei
Keyword(s):  
Heat Loss ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Radiative Heat ◽  
Slight Effect ◽  
Radiative Heat Loss ◽  
Total Heat Loss ◽  
Convective Heat Loss ◽  
Performance Curves ◽  
Variation Tendency

Solar cavity receiver is a key component to realize the light-heat conversion in tower-type solar power system. It usually has an aperture for concentrated sunlight coming in, and the heat loss is unavoidable because of this aperture. Generally, in order to improve the thermal efficiency, a layer of coating having high absorptivity for sunlight would be covered on the surface of the absorber tubes inside the cavity receiver. As a result, it is necessary to investigate the effects of the emissivity of absorber tubes on the thermal performance of the receiver. In the present work, the thermal performances of the receiver with different absorber emissivity were numerically simulated. The results showed that the thermal efficiency increases and the total heat loss decreases with increasing emissivity of absorber tubes. However, the thermal efficiency increases by only 1.6% when the emissivity of tubes varies from 0.2 to 0.8. Therefore, the change of absorber emissivity has slight effect on the thermal performance of the receiver. The reason for variation tendency of performance curves was also carefully analyzed. It was found that the temperature reduction of the cavity walls causes the decrease of the radiative heat loss and the convective heat loss.

scholarly journals Heat loss analysis of three coil cylindrical solar cavity receiver of parabolic dish for process heat

2019 ◽  
Vol 23 (Suppl. 4) ◽  
pp. 1301-1310
Author(s):  
Ramola Sinha ◽  
Nitin Gulhane ◽  
Jan Taler ◽  
Pawel Oclon
Keyword(s):  
Cost Effectiveness ◽  
Heat Loss ◽  
Total Heat ◽  
Fluid Temperature ◽  
Total Heat Loss ◽  
Wall Area ◽  
Single Coil ◽  
Receiver System ◽  
Parabolic Dish ◽  
Process Heat

The share of solar thermal energy for process heat at sub cooled temperature is estimated about 30% of the total demand. The assessment of heat loss from tubular receiver used for the process heat is necessary to improve the thermal efficiency and consequently the cost effectiveness of the parabolic dish receiver system. The study considers a modified three coil solar cavity receiver of wall area three times (approximately) as compared to the existing single coil receiver and experimentally investigates the effect of increases in cavity inner wall area, fluid inlet temperature (50-75?C), and cavity inclination angle (? = 0-90?) on the combined (total) heat loss from receiver under no wind condition. This paper also develops an analytical model to estimate the different mode of heat losses from the downward facing receiver. In the mean fluid temperature range of 50?C to 70?C, the total heat loss from three coil receiver is reduced up to 40.98% at 90? and 20% at 0? inclination, as compared to single coil receiver. The analytical modeling estimates very low heat loss from conduction (1-3%) and radiation (2-8%) and high heat loss from convection (97-89%). The heat loss by natural convection decreases sharply with increase in cavity inclination, while the heat loss by radiation and conduction increases slowly with inclination. A three coil cavity receiver might be considered in the design to reduce heat loss from parabolic dish receiver system to improve the thermal performance and cost effectiveness.

scholarly journals The Wind Test on Heat Loss from Three Coil Cavity Receiver for a Parabolic Dish Collector

2019 ◽  
Vol 128 ◽  
pp. 01006 ◽  
Author(s):  
Ramola Sinha ◽  
Nitin P. Gulhane ◽  
Paweł Ocłoń ◽  
Jan Taler ◽  
Rahimi Gorji
Keyword(s):  
Heat Loss ◽  
Total Heat ◽  
Inlet Temperature ◽  
Fluid Temperature ◽  
Wind Condition ◽  
Horizontal Position ◽  
Total Heat Loss ◽  
Maximum Heat ◽  
Mean Temperature ◽  
Parabolic Dish

The heat loss from cavity receiver in parabolic dish system determines the efficiency and cost effectiveness of the system. A modified three coil solar cavity receiver of inner wall area approximately three times of single coil receiver, is experimentally investigated to study the effect of fluid inlet temperature (Tfi=50°C to 75 °C) and cavity inclination angle (θ = 0° to 90°) on the heat loss from receiver under wind condition for head on wind and side on wind velocity at 3 m/s. Overall it was found that the natural and forced convection total heat loss increases with increase in mean fluid temperature. The combined heat loss decreases sharply with the increase in cavity inclination and observed to be maximum for horizontal position of receiver and minimum with the receiver facing vertically downward for all investigations. The maximum heat lossin wind test (V=3m/s) is 1045 W at θ=0° cavity inclination at mean fluid temperature 68 °C and minimum at 173 W θ=90° at 53°C. Total heat loss from the receiver under wind condition (V=3m/s) is up to 25% higher(1.25 times at 0° inclination) than without wind at mean fluid temperature ~70°C and minimum 19.64 % (1.2 times at 90° inclination) in mean temperature ~50 °C . In horizontal position of the receiver (θ=0°), the totalheat loss by head on wind is about 1.23 times (18% higher ) as compared to side on wind (at fluid mean temperature ~ 70°C). For receiver facing downward (θ=90°), for head-on wind, total heat loss is approximately the same as that for side-on wind.

Effect of radiative heat loss on steady hypersonic flow past a blunt body

1967 ◽  
Vol 29 (3) ◽  
pp. 485-494 ◽  
Author(s):  
M. I. G. Bloor
Keyword(s):  
Numerical Solution ◽  
Heat Loss ◽  
Blunt Body ◽  
Radiative Heat ◽  
Constant Density ◽  
Axially Symmetric ◽  
Radiative Heat Loss ◽  
Stagnation Region ◽  
Expansion Procedure ◽  
Axis Of Symmetry

Using the grey gas approximation, the effect of radiative heat loss on axially symmetric flows is studied. Using an expansion procedure about the axis of symmetry, a numerical solution for the stagnation region is found taking the shock to be spherical. The results of this calculation are compared with the results of Lighthill's non-radiative constant density solution.

scholarly journals Analysis of MHD Forced Convective Flow of Variable Fluid Properties over a Saturated Porous Medium with Thermal Radiation Effect

2016 ◽  
Vol 9 ◽  
pp. 47-65 ◽  
Author(s):  
Kolawole Sunday Adegbie ◽  
Adeyemi Isaiah Fagbade
Keyword(s):  
Porous Medium ◽  
Heat Loss ◽  
Convective Flow ◽  
Radiative Heat ◽  
Saturated Porous Medium ◽  
Fluid Velocity ◽  
Radiative Heat Loss ◽  
Variable Fluid Properties ◽  
Fluid Properties ◽  
Forced Convective Flow

The present paper addresses the problem of MHD forced convective flow in a fluid saturated porous medium with Brinkman-Forchheimer model, which is an important physical phenomena in engineering applications. The paper extends the previous models to account for effects of variable fluid properties on the forced convective flow through a porous medium in the presence of radiative heat loss using bivariate spectral relaxation method (BSRM). The dynamic viscosity and thermal conductivity of the newtonian fluid are assumed to vary linearly respectively, with temperature whereas the contribution of thermal radiative heat loss is based on Rosseland diffussion approximation. The flow model is described and expressed in form of a highly coupled nonlinear system of partial differential equations. The method of solution BSRM as proposed by Motsa [25] seeks to decouple the original system of PDEs to form a sequence of equations that can be solved in a computationally efficient manner. BSRM is an approach that applies spectral collocation independently in all underlying independent variable is executed to obtain approximate solutions of the problem. The proposed algorithm is supposed to be a very accurate, convergent and very effective in generating numerical results. The results obtained show a significant effects of the flow control parameters on the fluid velocity and temperature respectively. Consequently, the wall shear stress and local heat transfer rate of the present paper are compared with the available results in literatures. Remarkable impacts and a good agreement are found.

Cavity receiver thermal performance analysis based on total heat loss coefficient and efficiency factor

2018 ◽  
Vol 42 (6) ◽  
pp. 2284-2289 ◽  
Author(s):  
Qiangqiang Zhang ◽  
Xin Li ◽  
Zhifeng Wang ◽  
Zhi Li ◽  
Hong Liu ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Heat Loss ◽  
Thermal Performance ◽  
Efficiency Factor ◽  
Loss Coefficient ◽  
Total Heat ◽  
Total Heat Loss
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