scholarly journals Experimental investigation of the effect of temperature differentials on hydraulic performance and flow pattern of a sediment retention pond

2018 ◽  
Vol 77 (12) ◽  
pp. 2896-2906 ◽  
Author(s):  
Ehsan Hendi ◽  
Asaad Y. Shamseldin ◽  
Bruce W. Melville ◽  
Stuart E. Norris
Keyword(s):  
Residence Time ◽  
Hydraulic Performance ◽  
Effect Of Temperature ◽  
Sediment Retention ◽  
Small Temperature ◽  
Thermally Induced ◽  
Retention Pond ◽  
Retention Ponds ◽  
Sediment Retention Ponds ◽  
Counter Current

Abstract Existing studies on sediment retention ponds (SRPs) have examined the effects of pond layout, inlet and outlet geometry and the installation of baffles on the performance of the SRPs. However, the effects of a temperature difference between the ambient water in the pond and the inflow are often neglected, and the buoyancy forces arising from these differences in temperature can potentially change the flow in the pond and hence its hydraulic performance. This study has experimentally evaluated the effect of these temperature differences on the flow field and residence time in a retention pond for a range of temperature differences. As expected a cold inflow sinks to the bottom of the pond while a hot inflow remains at the surface, but in both cases the inflow flows more rapidly towards the outlet than is the case for isothermal inflow. A counter-current was observed at the bottom or the surface of the pond for colder or hotter influents, respectively. These thermally induced flows significantly reduced the residence time of the pond, reducing the hydraulic performance of the pond and causing severe short-circuiting. The results have also shown that the temperature differences in the pond decrease with time, yet small temperature differences persist with the pond remaining thermally stratified.

scholarly journals Effect of baffles on the hydraulic performance of sediment retention ponds

2016 ◽  
Vol 75 (9) ◽  
pp. 1991-1996
Author(s):  
Sher Khan ◽  
Bruce W. Melville ◽  
Mudasser Muneer Khan ◽  
Muhammad Shoaib ◽  
Asaad Shamseldin
Keyword(s):  
Physical Model ◽  
Residence Time ◽  
Hydraulic Performance ◽  
Large Area ◽  
Sediment Retention ◽  
Retention Pond ◽  
Retention Ponds ◽  
Sediment Retention Ponds

An investigation of the effect of baffles on retention pond performance using a physical model of an existing sediment retention pond is presented. Analysis of residence time (RTD curves) was used to compare the hydraulic performance of different arrangements of baffles in the pond. Five different arrangements for the design of baffles were studied. The results show that placing a single baffle to deflect the influent to a sediment retention pond does not improve pond performance; rather, it stimulates short-circuiting. This is contradictory to the literature and is considered to be a consequence of the model pond incorporating sloping walls, which is a novel aspect of this study. Most of the previous studies have neglected the effects of battered walls. Conversely, the inclusion of more than two baffles was found to increase the hydraulic performance. The results reported here are limited to small and narrow ponds where a large portion of the pond is batter (i.e. made up of sloping walls). For large area ponds, batter effects may be negligible and are likely to be different from those reported here.

Evaluation of hydraulic performance indices for retention ponds

2015 ◽  
Vol 72 (1) ◽  
pp. 10-21 ◽  
Author(s):  
Arash Farjood ◽  
Bruce W. Melville ◽  
Asaad Y. Shamseldin ◽  
Keith N. Adams ◽  
Sher Khan
Keyword(s):  
Hydraulic Performance ◽  
Hydraulic Efficiency ◽  
Hydraulic Analysis ◽  
Performance Indices ◽  
Sediment Retention ◽  
Retention Pond ◽  
Retention Ponds ◽  
Sediment Retention Ponds ◽  
Moment Index ◽  
Selection Of

Abstract Comprehensive hydraulic analysis of sediment retention ponds is commonly achieved through interpretation of residence time distribution and derivation of indices associated with short-circuiting and mixing. However, the availability of various indices indicates the need for careful selection of the most appropriate indices. This study compares some of the commonly used hydraulic performance indices, together with a new short-circuiting index, τ5, for five different flow regimes in a model sediment retention pond. The results show that τ5 was the best measure for short-circuiting. Among the mixing indices, only the Morril index correctly represented the physical behaviour of the experiments. In addition, two hydraulic efficiency indices, λ and a moment index (MI) were assessed and showed a good correlation with the short-circuiting and mixing indices, but MI was more reproducible than λ. Based on these results, this study recommends using τ5, Morril index and MI for analysis of hydraulic performance in sediment retention ponds.

The effect of different baffles on hydraulic performance of a sediment retention pond

2015 ◽  
Vol 81 ◽  
pp. 228-232 ◽  
Author(s):  
Arash Farjood ◽  
Bruce W. Melville ◽  
Asaad Y. Shamseldin
Keyword(s):  
Hydraulic Performance ◽  
Sediment Retention ◽  
Retention Pond

scholarly journals Hydraulic investigation of the impact of retrofitting floating treatment wetlands in retention ponds

2019 ◽  
Vol 80 (8) ◽  
pp. 1476-1484 ◽  
Author(s):  
Sher Khan ◽  
Muhammad Shoaib ◽  
Mudasser Muneer Khan ◽  
Bruce W. Melville ◽  
Asaad Y. Shamseldin
Keyword(s):  
Root Length ◽  
Longitudinal Axis ◽  
Hydraulic Performance ◽  
Treatment Wetlands ◽  
Experimental Investigations ◽  
Retention Pond ◽  
Retention Ponds ◽  
Floating Treatment Wetlands ◽  
The Impact ◽  
Stormwater Retention

Abstract This paper describes the laboratory experimental investigations undertaken to analyse the influence of floating treatment wetlands (FTWs) on the hydraulic performance of a stormwater retention pond. Two experimental series were conducted, each focussed on investigating the influence of placing an FTW in a pond with firstly the inflow entering the retention pond from an inlet positioned 0.25 m offset from the longitudinal axis of the pond, and secondly the inlet positioned at the longitudinal axis of the pond. For both series of experiments, tests were undertaken at 1 l/s and 1.5 l/s, and with and without an artificial FTW installed. This study is the first to investigate the hydraulic impact of FTWs and their root systems on the performance of stormwater retention ponds. The results presented in this study suggest that FTWs are a viable method to minimise hydraulic inefficiencies, thereby increasing retention time and optimising hydraulic performance of stormwater retention ponds. The results highlight the importance of plant root characteristics. The optimal arrangement of root length is LR/DP = 0.5, where LR = root length and DP = pond depth. The results also indicate that the spatial variability of vegetation has a significant impact on the hydraulic performance of the pond.

Retrofitting a stormwater retention pond using a deflector island

2011 ◽  
Vol 63 (12) ◽  
pp. 2867-2872 ◽  
Author(s):  
S. Khan ◽  
B. W. Melville ◽  
A. Y. Shamseldin
Keyword(s):  
Physical Model ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Stormwater Runoff ◽  
Sediment Removal ◽  
Retention Pond ◽  
Retention Ponds ◽  
Runoff Analysis ◽  
Stormwater Retention

Stormwater retention ponds are one of the principal methods to treat stormwater runoff. Analysis of residence time distribution (RTD) curves can be used to evaluate the capability of these ponds for sediment removal. Deflector islands have been suggested as a means of improving the performance of retention ponds, due to their diffusing the inlet jet. In this study, the effect of an island on retention pond performance was investigated using a physical model of an existing stormwater retention pond. The physical model is a trapezoidal pond having top dimensions 4.1 × 1.5 × 0.23 m and side slopes of 2:1 (h:v). Three different arrangements were studied. The results show that placing an island to deflect the influent to a stormwater retention pond does not improve pond performance, rather it stimulates short-circuiting. This unexpected behaviour, in relation to previous studies, is considered to be a consequence of the model pond incorporating sloping walls; which is a novel aspect of this paper.

scholarly journals Torrefaction of Napier Grass and Oil Palm Petiole Waste Using Drop-type Pyrolysis Reactor

2021 ◽  
Author(s):  
Syazmi Zul Arif Hakimi Saadon ◽  
Noridah Osman ◽  
Moviin Damodaran ◽  
Shan En Liew
Keyword(s):  
Residence Time ◽  
Oil Palm ◽  
Waste Product ◽  
Calorific Value ◽  
Napier Grass ◽  
Effect Of Temperature ◽  
Energy Yield ◽  
Pyrolysis Reactor ◽  
Parameter Ranges ◽  
Two Parameters

Abstract Interest in torrefaction has improved along the recent years and it has been studied extensively as a mean of preparing solid fuels. Biomass to be considered as a renewable source of energy must endeavor improvement continuously and where it is more sustainable going forward in which can come from waste product, wild and cultivated plant. The aim of this study is to investigate the effect of temperature and residence time of wild Napier grass and Oil palm petiole from waste. The torrefied samples were derived by pyrolysis reactor mimicking torrefaction procedure. The temperature parameter ranges between 220 and 300 ℃ while residence time parameter is from 10 minutes to 50 minutes of reaction. It was found that as temperature and time increasing, moisture content and amount of O and H atoms decreases as well as both mass and energy yield, but calorific value and the energy density increase along with both two parameters. Between the two parameters, the temperature variation shows more significant changes to the torrefied samples as compared time. The optimized temperature and time are found to be 260 ℃ and 30 minutes, respectively. Remarkably, the usage of pyrolyzer as torrefaction reaction has proved to be a good option since they share similar characteristics while can also produce product with similar properties reflecting torrefaction process.

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