Numerical models of solar distillation device: present and previous

In this paper, a detailed comparison of a few numerical models (with and without considering humid air properties) for the estimation of water production from a solar water distillation device is investigated. An extensive laboratory production experiments were executed under fifteen sets of external conditions to find the properties of evaporation and condensation coefficients to incorporate with the present evaporation and condensation models (two unique and independent theoretical models), respectively. The calculation accuracy of the evaporation flux computed by two evaporation models (present and previous), Dunkle's and Ueda's model, and of the hourly condensation flux estimated by two condensation models (present and previous) was examined using the field experimental results. It was found that the previous evaporation and condensation models using empirical relationships extremely overestimated and underestimated the observed production flux, respectively. The evaporation flux calculated by the conventional models of Dunkle and Ueda notably underestimated and overestimated the observed values, respectively. Finally, it is revealed that the present models have the smallest deviation between the calculated and the observed values among these six models and can predict the daily production flux

Editorial: urban nature-based solutions and green infrastructure as strategies for climate change adaptation

info:eu-repo/semantics/publishedVersio

Evaporation Phenomenon Inside a Solar Still: From Water Surface to Humid Air

This demonstration illustrates how the water cycle helps to purify water. Students are introduced to the key terms, which are evaporation and condensation. They discover that evaporation is defined as the process through which a liquid becomes a vapor, while condensation is simply the reverse. Students also learn that in the case of water, the main mechanisms for evaporation and condensation are heating and cooling, respectively. Educational levels: Intermediate elementary, Primary elementary

Artificial mixing of lake water by bubble plume and effects of bubbling operations on algal bloom

In order to develop a method of predicting and assessing lake eutrophication, which is a serious environmental problem, and to propose effective measures for improvement of water quality, this paper presents a composite model of the mixing of lake water by air bubble plume and lake phytoplankton model. The equations of heat aid mass transfer in the lake were solved together with equations governing physical and biological processes under real atmospheric conditions coupled with an integrated model of bubble plume. The verification of the model was conducted using data of Lake Calhoun (USA). Using the developed model, numerical experiments were carried out far an imaginary lake in the Hiroshima region of Japan with different gas flow rates of bubble plume, different numbers of bubble ports, different starting dates of bubbler and different bubbler depths. The optimization of the improvement of water quality in the lake can be obtained by using the appropriate gas flow rate and number of bubble ports, and applying it at an appropriate period of the year

Prototype Experiments Assessing Arsenic and Iron Removal Efficiencies through Adsorption Using Natural Skye Sand

Based on earlier batch and column experimental results, it was established that Skye sand is suitable for removing arsenic from water through adsorption. As a real-size prototype may not always replicate results from batch and column experiments, this paper presents experimental results on arsenic removal through a prototype arsenic filter using the same Skye sand used in the batch and column experiments. As arsenic-contaminated water is often associated with a high concentration of iron, which causes blockage of the filter system, this study also investigates the removal of iron from the water through the same filter media. First, several physical properties of the Skye sand were established through XRF, XRD, SEM and EDX analyses. Then, a real-size prototype was made based on an earlier design of a similar filter made of iron oxide-coated sand (IOCS). It was found that the current filter is capable of removing arsenic consistently to a level below the detection limit (0.05 µg/L) for a considerable period (up to 150 bed volumes). Additionally, the same filter is capable of removing iron to a level below the WHO-acceptable limit (0.3 mg/L). Analytical calculation suggests that the current prototype filter with Skye sand can produce arsenic-free water continuously for 600 days (100 L per day) with a feed arsenic concentration of 500 µg/L

Improved continuing losses estimation using initial loss-continuing loss model for medium sized rural catchments

Problem statement: The rainfall based design flood estimation techniques are commonly adopted in hydrological design and require a number of inputs including information on soil loss characteristics. Approach: A conceptual loss model known as the ‘Initial Loss-Continuing Loss (ILCL) model’ is widely used in Australia. Results: The Initial Loss (IL) occurs at the beginning of the rainfall event, prior to the commencement of surface runoff and the Continuing Loss (CL) is the average rate of loss throughout the remainder of the storm. The currently recommended design loss values depicted in “Australian Rainfall and Runoff Vol. 1” for Queensland (Australia) has some basic limitations. This study investigated how more accurate CL values can be estimated and derived for medium sized tropical Queensland catchments using long term rainfall and streamflow data. Accuracy in CL estimation has got significant implications in the estimation of design floods. Conclusion/Recommendations: The results showed that CL value is not fixed and constant through out the duration of the storm but the CL value decays with the duration of the storm

Use of Teleconnections to Predict Western Australian Seasonal Rainfall Using ARIMAX Model

Increased demand for engineering propositions to forecast rainfall events in an area or region has resulted in developing different rainfall prediction models. Interestingly, rainfall is a very complicated natural system that requires consideration of various attributes. However, regardless of the predictability performance, easy to use models have always been welcomed over the complex and ambiguous alternatives. This study presents the development of Auto–Regressive Integrated Moving Average models with exogenous input (ARIMAX) to forecast autumn rainfall in the South West Division (SWD) of Western Australia (WA). Climate drivers such as Indian Ocean Dipole (IOD) and El Nino Southern Oscillation (ENSO) were used as predictors. Eight rainfall stations with 100 years of continuous data from two coastal regions (south coast and north coast) were selected. In the south coast region, Albany (0,1,1) with exogenous input DMIOct–Nino3Nov, and Northampton (0,1,1) with exogenous input DMIJan–Nino3Nov were able to forecast autumn rainfall 4 months and 2 months in advance, respectively. Statistical performance of the ARIMAX model was compared with the multiple linear regression (MLR) model, where for calibration and validation periods, the ARIMAX model showed significantly higher correlations (0.60 and 0.80, respectively), compared to the MLR model (0.44 and 0.49, respectively). It was evident that the ARIMAX model can predict rainfall up to 4 months in advance, while the MLR has shown strict limitation of prediction up to 1 month in advance. For WA, the developed ARIMAX model can help to overcome the difficulty in seasonal rainfall prediction as well as its application can make an invaluable contribution to stakeholders’ economic preparedness plans

Daily water balance modeling for investigating effectiveness of stormwater harvesting for golf course

As an alternative water source, feasibility of collection and reuse of stormwater has been investigated for golf course irrigation in Western Sydney area. In order to visualize effectiveness of proposed stormwater harvesting, a numerical modelling and investigation was carried out using a daily water balance model. From historical data for the area, three calendar years were chosen as a dry year (1st decile), average year (5th decile) and wet year (9th decile). Mathematical model considered actual rainfall and contributing catchment area. Evaporation from water surface, evapo-transpiration and infiltration are considered as losses. Calculated runoff was routed through an existing pond/storage. Once pond became full, subsequent runoffs from the upstream catchments were lost from water storages through overflow. Water demand was calculated throughout the year, considering water requirements for existing grass types as well as number of rainy days. Through model simulation, cumulative water demands, available water volumes and water supply deficits were calculated for three different climatic conditions (ie. dry, average and wet) under different storage volumes and contributing catchment areas. It was found that none of the modeled scenarios were able to achieve a secure supply for golf course watering. If water is taken only from harvested storage, even in wet year there will be water supply deficit. However, if the pond storage volume is increased, stored stormwater would be able to meet some portion of irrigation water demand in average years and wet years. However, there would be virtually no demand met in a dry year. If storage volume is increased continually, at one stage increased storage volume will not provide any extra benefit due to lack of inflow from catchment. If catchment area is increased, although available water for irrigation will be increased, however water supply deficit will also increase due to increased area of golf course, which has to be irrigated also. With increased catchment area, in wet year available water is decreasing. This is because with the increased catchment area water demand increased, however stored water was not enough due to limited storage volume