scholarly journals Estimation of convective heat losses from conical cavity receiver of solar parabolic dish collector under wind conditions and receiver orientations

2021 ◽  
Vol 313 ◽  
pp. 11001
Author(s):  
Abhinav Rajan ◽  
K. S. Reddy
Keyword(s):  
Wind Speed ◽  
Heat Loss ◽  
Convective Heat ◽  
Heat Losses ◽  
High Wind ◽  
Height Ratio ◽  
High Wind Speed ◽  
Conical Cavity ◽  
Parabolic Dish ◽  
Influential Parameters

The parabolic dish collector is one of the recognized concentrated solar power systems based on point focusing, which provides high-temperature heat, high concentration ratio, and low heat loss. This system consists of a parabolic reflector and a cavity receiver situated in the focus line. In this work, the conical cavity receiver with an aperture diameter of 0.5 m is considered for a 100 m2 parabolic reflector having a focal to diameter ratio of 0.48. Due to the complexity of flow and temperature profile, the estimation of convective heat loss is a difficult task in a cavity receiver. More heat losses are associated with high temperature obtained in the cavity receiver of the parabolic dish collector. Due to diverse wind effect, the convective heat losses ramp up, which significantly influences the thermal performance of the concentrating power system. The present work aims to investigate the heat losses due to convection from the conical cavity receiver. The numerical investigation was performed using ANSYS Fluent 20R1 to calculate the convective heat losses from the conical cavity receiver of varying diameter to height ratio for varying wind speed, receiver orientation in head-on, and back-on wind flow directions. The considered influential parameters are varying from 0.5 to 1.5 for diameter to height ratio (d/h), 0° to 90° for receiver orientation (γ), 0 to 10 m/s for wind speed (V). The heat losses are highest at 60° and 75° receiver orientation for d/h = 0.5 and d/h = 1-1.5, respectively, at high wind speed in head-on condition, whereas in back-on wind condition, 30° receiver orientation has more heat losses among all the d/h values at high wind speed. The heat loss at 90° receiver orientation is low for 4-10 m/s. The trends of heat loss curve at receiver orientations for given wind conditions are similar for velocity more than 2 m/s. The result reveals that the considered influential parameters have a remarkable effect on convective heat losses from the cavity receiver.

scholarly journals Numerical study of Flow patterns and performance of a coupled cavity-dish system under different focal lengths

2021 ◽  
Author(s):  
Muhammad Uzair ◽  
Mubashir Ali Siddiqui ◽  
Usman Allauddin
Keyword(s):  
Heat Loss ◽  
Convective Heat ◽  
Numerical Study ◽  
Focal Length ◽  
Heat Losses ◽  
Operating Conditions ◽  
Convective Heat Loss ◽  
Parabolic Dish ◽  
And Performance ◽  
Coupled Cavity

The effectiveness of the parabolic dish system (PDS) is greatly affected by the heat losses associated with high temperatures. The complexity of flow and temperature patterns in and around the cavity receiver makes it a challenging task to determine the convective heat loss from the cavity. Various studies have been carried out to determine the convection heat losses from isolated cavities of different shapes. In the presence of dish structure, the free stream wind may affect the stability of structure and the heat losses from the PDS. In this study, effect of focal length on the performance of the coupled cavity-dish system was analyzed using numerical simulations. The loading and the convective heat loss from the cavity were examined with three different cavity positions and different operating conditions in the presence of the dish. The results showed that the shallow dish experienced higher local air velocities near the cavity receiver than in the case of the deep dish. It was concluded that the heat loss is a stronger function of tilt angle rather than focal length, and in essence, the heat losses due to variation of this are negligible.

BEHAVIOR OF MECHANICALLY ANCHORED WATERPROOFING MEMBRANE EXPOSED IN HIGH WIND SPEED OF ACTUAL WIND

2006 ◽  
Vol 71 (610) ◽  
pp. 29-34 ◽  
Author(s):  
Hiroyuki MIYAUCHI ◽  
Nobuo KATO ◽  
Hirokazu ICHIKAWA ◽  
Takanori SASAKI ◽  
Kyoji TANAKA
Keyword(s):  
Wind Speed ◽  
High Wind ◽  
High Wind Speed ◽  
Waterproofing Membrane

Haul-out behaviour and densities of ringed seals (Phoca hispida) in the Barrow Strait area, N.W.T.

1979 ◽  
Vol 57 (10) ◽  
pp. 1985-1997 ◽  
Author(s):  
Kerwin J. Finley
Keyword(s):  
Wind Speed ◽  
Early Morning ◽  
Maximum Density ◽  
Stable Population ◽  
The Sun ◽  
High Wind ◽  
Phoca Hispida ◽  
High Wind Speed ◽  
Ringed Seals ◽  
Calm Weather

Numbers of ringed seals hauled out on the ice began to increase in early June. Numbers on the ice were highest from 0900 to 1500 hours Central Standard Time and lowest (average 40–50% of peak) in early morning. Seals commonly remained on the ice for several hours, and occasionally (during calm weather) for > 48 h. Numbers on the ice were reduced on windy days and possibly also on unusually warm, bright and calm days. Seals tended to face away from the wind (particularly with high wind speed) and oriented broadside to the sun. Seals usually occurred singly (60–70% of all groups) at their holes.Numbers of seals hauled out at Freemans Cove remained relatively constant during June (maximum density 4.86/km2), whereas at Aston Bay numbers increased dramatically to a maximum density of 10.44/km2 in late June. The increase was thought to be due to an influx of seals abandoning unstable ice. The density of seal holes at Freemans Cove (5.92/km2) was much higher than at Aston Bay (2.73/km2). The ratio of holes to the maximum numbers of seals (1.12:1) at Freemans Cove represents a first estimate of this relationship in an apparently stable population.

scholarly journals Evaluation of the AMPS Boundary Layer Simulations on the Ross Ice Shelf, Antarctica, with Unmanned Aircraft Observations

2017 ◽  
Vol 56 (8) ◽  
pp. 2239-2258 ◽  
Author(s):  
Jonathan D. Wille ◽  
David H. Bromwich ◽  
John J. Cassano ◽  
Melissa A. Nigro ◽  
Marian E. Mateling ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Relative Humidity ◽  
High Wind ◽  
Ice Shelf ◽  
High Wind Speed ◽  
Near Surface ◽  
Ross Ice Shelf ◽  
Low Cloud ◽  
The Antarctic

AbstractAccurately predicting moisture and stability in the Antarctic planetary boundary layer (PBL) is essential for low-cloud forecasts, especially when Antarctic forecasters often use relative humidity as a proxy for cloud cover. These forecasters typically rely on the Antarctic Mesoscale Prediction System (AMPS) Polar Weather Research and Forecasting (Polar WRF) Model for high-resolution forecasts. To complement the PBL observations from the 30-m Alexander Tall Tower! (ATT) on the Ross Ice Shelf as discussed in a recent paper by Wille and coworkers, a field campaign was conducted at the ATT site from 13 to 26 January 2014 using Small Unmanned Meteorological Observer (SUMO) aerial systems to collect PBL data. The 3-km-resolution AMPS forecast output is combined with the global European Centre for Medium-Range Weather Forecasts interim reanalysis (ERAI), SUMO flights, and ATT data to describe atmospheric conditions on the Ross Ice Shelf. The SUMO comparison showed that AMPS had an average 2–3 m s−1 high wind speed bias from the near surface to 600 m, which led to excessive mechanical mixing and reduced stability in the PBL. As discussed in previous Polar WRF studies, the Mellor–Yamada–Janjić PBL scheme is likely responsible for the high wind speed bias. The SUMO comparison also showed a near-surface 10–15-percentage-point dry relative humidity bias in AMPS that increased to a 25–30-percentage-point deficit from 200 to 400 m above the surface. A large dry bias at these critical heights for aircraft operations implies poor AMPS low-cloud forecasts. The ERAI showed that the katabatic flow from the Transantarctic Mountains is unrealistically dry in AMPS.

Research on Low-Wind-Speed Wind Power

2013 ◽  
Vol 448-453 ◽  
pp. 1811-1814
Author(s):  
Hai Hui Song ◽  
Jian Jun Wang ◽  
Zhi Hua Hu ◽  
Jin Zhou
Keyword(s):  
Wind Speed ◽  
Wind Power ◽  
Research Development ◽  
High Wind ◽  
Power Development ◽  
High Wind Speed ◽  
Low Wind Speed ◽  
Key Technologies ◽  
Wind Power Development

For high-wind-speed wind power development and problems, propose development and application of low-wind-speed wind power (LWSP). Analysis of the characteristics of LWSP , advantages and necessity of development and application of it. Research the key technologies of LWSP development. It ultimately lay the foundation for research, development and application of LWSP technologies.

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