Pipe sizing of district cooling distribution network using implicit Colebrook-White equation

An implicit solution of Colebrook-White equation was used in calculating the friction factor for commercial steel pipes using Newton-Raphson method with Reynolds number ranging from 4.0×103 to 1.3×107. Initial value for iterative friction factor estimation was based on expanded form of Colebrook-White equation for larger values of Reynolds number with tolerance value of 1.0×10-8. Numerical results were compared with known explicit solutions and iterative procedure proposed by Lester in which, their mean difference, root-mean square deviation, mean relative error and correlation coefficient were evaluated. Correlation coefficients equal to unity and overall mean relative error of 4.821×10-8 were achieved for all fifteen (15) pipe cases with nominal diameters ranging from 100mmto 1,500mmwhen compared with iterative solution suggested by Lester. Student\u27s t-test for paired data was also used which yielded a calculated t-value of -5.406×10-4. Combining the piping network design criteria with the logical structure of friction factor calculation determines the pipe size of distribution network and defines the boundaries of chilled-water velocities at different pressure drop limits as a function of commercial steel pipe diameter according to ANSI B36.1

Risk Analysis of Power Supply in San Juan, Surigao City, Philippines Due to Extreme Floods

The power supply system and its network components, like any other lifeline, are at risk due to extreme floods. Although various adaptive measures by the power producer can reduce this risk, the infrastructure (demand side) connected to the substation are still at risk to extreme inundation primarily because of its elevation, thus rendering the adaptation measures inadequate. In this paper, the authors use geographic information technology to quantify the risk of power loss to the consumers and the ensuing economic loss to the power producer considering various extreme inundation events. These extreme flood events were based on hypothetical rainfall with return periods of 2, 5, 10, 25 and 50 years. Specifically, the authors developed a risk curve for the power supply system in barangay San Juan, Surigao City, Surigao Del Norte, Philippines. The study shows that the percentage of households vulnerable to extreme floods for each return period are 22, 91, 93, 94 and 96. This power outage translates to a potential money loss range from US 1800 to US 36,000 for the power provider. To reduce the risk the following adaptation measures can be adopted by the local government (a) improve the drainage system, (b) rehabilitate Surigao River and consider buffer zone / overflow structures, (c) proper zoning and relocation of flood residents to elevated areas and (d) install new transformers to isolate households that are frequently flooded so power outage is reduced during extreme events. © 2014 American Society of Civil Engineers

Perceptions and attitudes toward eco-toilet systems in rural areas: A case study in the Philippines

© 2018 by the authors. Death due to diseases from poor sanitation is a serious global issue and it has become one of the priorities of the United Nations\u27 Sustainable Development Goals (i.e., SDG6). This SDG6 aims to provide adequate improved sanitation facilities to over 2.3 billion people around the world who have no or limited access to sanitation, wherein more than two-thirds of these un-served people live in rural areas. One of the strategies for addressing this global issue is through emerging sustainable sanitation technologies such as the Eco-Toilet System (ETS), which uses small amounts of water or is even waterless and recovers nutrients from human waste thereby promoting water-energy conservation, improved sanitation and supplement nutrients essential to plant growth. Social acceptance, however, remains a key barrier in deploying the ETS. A social perception study on the use of the ETS was conducted in a rural community in Mulanay, Philippines. The researchers analyzed the proposed combined technology acceptance model and theory of planned behavior (C-TAM-TPB) using multiple linear regression and the Mann-Whitney U-test to evaluate the perceptions and attitudes of a rural community towards the use of the ETS. The results showed that more than 50% of the respondents are aware of the nutrient value of human excreta and believe that it is usable as fertilizer; however, less than 25% prefer to utilize it for food production. Results also indicate that the behavior of the users is driven by their attitude (β = 0.420, p-value \u3c 0.010). Moreover, the Mann-Whitney U-test results revealed that people who are knowledgeable of the nutrient value of human excreta and are willing to collect them have more positive attitude towards the ETS