15 research outputs found
Thermoresponsive ionic liquids and hydrogels for thermally driven forward osmosis water treatment systems
No full textForward osmosis (FO) is an alternative water treatment approach which relies on the osmotic force of concentrated solution, referred to as draw solution (DS), to extract water from relatively lower concentration solution. However, a lack of framework for designing FO DSs and their implementation in FO processes requiring DS regeneration has hindered FO development. This study proposes a framework for design of FO DSs especially thermally responsive DSs and their energetic assessment in FO water treatment process to mitigate high specific energy consumption (SEC). This work used multi-criteria analysis based on physicochemical characteristics of DS alone in contrast with earlier DS assessments to identify promising draw candidates and quantified desirable DS performance metrics. Promising thermally responsive DS were found to typically have osmotic density 40 kWh/m3 while achieving recovery ratio of >0.6 and containing residual DS of <15 wt.%. Thermally responsive hydrogels were found to minimally improve water quality of recovered water by reducing residual DS to ~10 wt.%. Therefore, a nanofiltration post-treatment process is recommended to produce potable quality water. The thermally responsive DS performance metrics and the developed modeling framework will aid in development of FO water treatment process prototypes that utilize low-grade thermal energy
Time Overrun in Pre-Construction Planning Phase of Construction Projects
No full textConstruction industry plays a significant role in fulfilling the major requirements of the human being. It is one of the major constituents of every developed country. Although the construction industry of both the developing and developed countries encompasses a major part of the economy, and millions of rupees are utilized every year on various kinds of construction projects. But, this industry is facing numerous hurdles in terms of its budget and timely completion. Construction projects generally consist of several phases like planning, designing, execution, and finishing. This research study aims to determine the significant factors of time overrun in pre-construction planning (PCP) phase of construction projects in Pakistan. Questionnaires were distributed by various means and responses of respondents were compiled and collected data were then analyzed through a statistical technique using SPSS version 24. Major causes of time overrun in pre-construction planning phase; which is an extremely important phase of construction projects, were revealed. The research conclusion will provide a pathway for stakeholders to pay attention to the mentioned causes to overcome the major issue of time overrun
Exploring Types of Waste Generated: A Study of Construction Industry of Pakistan
No full textThe construction sector is responsible for providing fundamental physical structure required for living and survival of human life. Increased development works have led in resulting the massive amount of waste generation in developing countries. Due to poor management system on sites, it has become more crucial and exerts several negative impacts on society and the environment. This Unused waste material has a negative impact on the ecosystem and needs a considerable amount of money for recycling, reusing and disposal of the waste. Like other developing countries Pakistan is spending a significant portion of its GDP on handling construction waste. Among the several other factors, the key contributes are highlighted in this study. This study is exploratory work investigating the types of construction waste generated on site and their relative impact of the project cost in construction projects of Pakistan. Through questionnaire the opinion of clients, consultant and constructor have been taken to identify the major types of waste having more impacts on cost and time. Through Average index, severity index and importance index, the probability of occurrence of waste through different materials, severity level of waste production by these materials, and the overall effect of all waste generating materials have been found respectively. Among the materials sand, concrete, tile is the most common materials, which are responsible for a waste generation while time and cost are the two most common non-physical waste generating factors
Exploring Types of Waste Generated: A Study of Construction Industry of Pakistan
Full text linkThe construction sector is responsible for providing fundamental physical structure required for living and survival of human life. Increased development works have led in resulting the massive amount of waste generation in developing countries. Due to poor management system on sites, it has become more crucial and exerts several negative impacts on society and the environment. This Unused waste material has a negative impact on the ecosystem and needs a considerable amount of money for recycling, reusing and disposal of the waste. Like other developing countries Pakistan is spending a significant portion of its GDP on handling construction waste. Among the several other factors, the key contributes are highlighted in this study. This study is exploratory work investigating the types of construction waste generated on site and their relative impact of the project cost in construction projects of Pakistan. Through questionnaire the opinion of clients, consultant and constructor have been taken to identify the major types of waste having more impacts on cost and time. Through Average index, severity index and importance index, the probability of occurrence of waste through different materials, severity level of waste production by these materials, and the overall effect of all waste generating materials have been found respectively. Among the materials sand, concrete, tile is the most common materials, which are responsible for a waste generation while time and cost are the two most common non-physical waste generating factors
Energy performance of GCC-specification LCC optimized dedicated outdoor air system configurations coupled to an air-cooled outdoor unit
Full text linkDirect expansion (DX) dedicated outdoor air system is shown to be a cost-effective energy efficient complement to ductless variable refrigerant flow and radiant cooling systems by providing conditioned ventilation air at the required set point temperature and relative humidity in an energy efficient manner. We compare five balanced flow dedicated outdoor air system configurations under typical office/lab ventilation loads coupled to an air-cooled outdoor unit for 24 Gulf Cooperation Council (GCC) locations representing GCC climates. All configurations use an enthalpy recovery wheel (ERW) to remove heat and moisture from intake air—before it reaches the active DX dehumidification element—by passive heat and mass transfer to the exhaust stream. It is found that of two run-around heat exchanger configurations, using a rotary heat wheel across the evaporator is a more efficient configuration than placing the heat wheel (HW) between the supply and return air streams. Furthermore, adding a subcooling coil for reheat in parallel to the HW results in higher efficiency than adding the coil in series with the HW. The Life cycle cost optimized ERW and HW effectiveness for the configuration with HW between supply and return air was found to be 0.86 while the ranges for run-around HW configurations with subcooling/reheat were found to be 0.8–0.85 for ERW and 0.74-0.82 for HW in GCC climates with significant dehumidification loads. Thus, the evaporator run-around HW reduces the volume, mass and cost of the DOAS unit while providing higher overall efficiency
Exploring the role of building information modeling in construction safety through science mapping
No full textOptimizing Energy Use, Cost and Carbon Emission through Building Information Modelling and a Sustainability Approach: A Case-Study of a Hospital Building
No full textThe construction industry (CI) has a significant impact on the environment and on climate change due to the emission of greenhouse gases like carbon dioxide. Globally accepted Sustainable Development Goals (SDG), specifically SDG 7 (Access to Affordable, Reliable, Sustainable and Modern Energy for All), SDG 9 (Industry, Innovation and Infrastructure), and SDG 11 (Sustainable Cities and Communities) stress the responsible utilization of energy in various industries, including construction. The CI uses almost half of the world’s produced energy. Therefore, this research presents insights into the efficient use of energy in the building sector and shows how energy efficiency can be achieved by altering different parameters and components like orientation, materials, glazing, and HVAC systems through a case study of a hospital building in Green Building Studio (GBS). This paper also aims to use the Building Information Modelling (BIM) approach to make environmentally sustainable decisions to reduce energy waste in projects. Initially, beneficial factors of BIM on green buildings were identified in the literature and later ranked, based on expert opinions collected using a set of questionnaires. Average Index was used for data analysis. The identified benefits were validated by conducting energy analyses on a hospital model through 3D BIM. It was concluded that a substantial share of energy cost, carbon dioxide (CO2), and electricity can be saved using this approach. It was determined that a quick and sustainable design process, improved energy efficiency, enhanced building performance, and provision of better design alternatives are the key benefits of the adoption of BIM by such projects. A Cronbach’s alpha value of 0.822 was obtained, which further validates the results. The proposed approach may lead future structures to be sustainable and enriches the culture of energy-efficient green buildings
Flux Performance Modeling of Forward Osmosis Draw Solutions in the Absence of Mass Diffusivity Data
No full textA forward osmosis (FO) flux modeling approach is presented
to enable
existing models to be used when the mass diffusivity is not known,
and the mass transfer resistance for the flow channel geometry is
uncharacterized. The proposed method only requires knowledge of common
physicochemical properties such as density, viscosity, and osmotic
pressure, along with the flow conditions (e.g., Reynolds number) in
the FO module, which are much easier to obtain than mass diffusivity.
The proposed method was found to predict water fluxes to within 20%
root-mean-squared percentage error over a wide range of draw solution
concentrations for inorganic and organic salts. It was also found
that the proposed approach estimation accuracy is sensitive to specific
reverse salt flux variation with the draw concentration of the flux
training data. The proposed first-principles modeling procedure is
expected to be useful for researchers to estimate FO flux performance
for novel draw compounds and uncharacterized flow channels
