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.

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

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

scholarly journals Fitness-related differences in the rate of whole-body total heat loss in exercising young healthy women are heat-load dependent

2018 ◽  
Vol 103 (3) ◽  
pp. 312-317 ◽  
Author(s):  
Dallon T. Lamarche ◽  
Sean R. Notley ◽  
Martin P. Poirier ◽  
Glen P. Kenny
Keyword(s):  
Heat Loss ◽  
Heat Load ◽  
Total Heat ◽  
Whole Body ◽  
Total Heat Loss ◽  
Healthy Women

A Comparative Numerical Study on Conjugate Natural Convection From Vertical Hollow Cylinder With Finite Thickness Placed on Ground and in Air

2020 ◽  
Vol 13 (2) ◽  
Author(s):  
Manoj Kumar Dash ◽  
Sukanta Kumar Dash
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Heat Loss ◽  
Hollow Cylinder ◽  
Average Nusselt Number ◽  
Total Heat ◽  
Outer Diameter ◽  
Thermal Plume ◽  
Total Heat Loss

Abstract The present work reports a comparative analysis of natural convection heat transfer from a thick hollow vertical cylinder either placed on the ground or suspended in the air. The numerical simulations have been performed by varying the cylinder length to its outer diameter (L/Do) in the range of 0.2–20, the thickness ratio (Di/Do) in a range of 0.5–0.9, and Rayleigh number (Ra) from 104 to 108. The flow and heat transfer characteristics have been delineated precisely with the presentation of the thermal plume and flow field in the vicinity of the cylinder. The variation of average Nusselt number (Nu), local Nu, and contribution to total heat loss from different surfaces with the pertinent parameters have been elucidated graphically. The average Nu is always more for the cylinder in the air compared with the case when it is on the ground. However, the difference between the Nu for these two cases diminishes, as the L/Do increases. It has also been found that the contribution to total heat loss from the inner surface of the hollow cylinder suspended in air increases with L/Do, attains a peak, and decreases sharply. Cooling time curves for the cylinder placed in air or on the ground have been described precisely. Finally, a correlation for the average Nusselt number as a function of all the pertinent parameters has been proposed that can be useful for industrial and academic purposes.

scholarly journals Self-reported physical activity level does not alter whole-body total heat loss independently of aerobic fitness in young adults during exercise in the heat

2019 ◽  
Vol 44 (1) ◽  
pp. 99-102 ◽  
Author(s):  
Dallon T. Lamarche ◽  
Sean R. Notley ◽  
Martin P. Poirier ◽  
Glen P. Kenny
Keyword(s):  
Physical Activity ◽  
Young Adults ◽  
Oxygen Consumption ◽  
Heat Loss ◽  
Aerobic Fitness ◽  
Total Heat ◽  
Activity Level ◽  
Peak Oxygen Consumption ◽  
Whole Body ◽  
Total Heat Loss

We evaluated whether self-reported physical activity (PA) level modulates whole-body total heat loss (WB-THL) as assessed using direct calorimetry in 10 young adults (aged 22 ± 3 years) matched for rate of peak oxygen consumption (an index for aerobic fitness), but of low and high self-reported PA, during 3 incremental cycling bouts (∼39%, 52%, and 64% peak oxygen consumption) in the heat (40 °C). We showed that level of self-reported PA does not appear to influence WB-THL independently of peak oxygen consumption.

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