A review of the water desalination systems integrated with renewable energy

Water and energy are indispensable entities for any flourishing life and civilization. The water and energy scarcities have emerged due to the dramatic growth in the population, standards of living, and the rapid development of the agricultural and industrial sectors. Desalination seems to be one of the most promising solutions to the water problem; however, it is an intensive energy process. The integration of the renewable energy into water desalination systems has become increasingly attractive due to the growing demand for the water and energy, and the reduction of the contributions to the carbon footprint. The intensive investigations on the conventional desalination systems, especially in the oil-rich countries have somewhat overshadowed the progress and implementation of the renewable energy desalination (RED) systems. The economic performance evaluation of the RED systems and its comparison with conventional systems is not conclusive due to many varying factors related to the level of technology, the source of energy availability, and the government subsidy. The small RED plants have a high capital cost, low efficiency and productivity which make RED systems uncompetitive with the conventional ones. However, the selection of the small RED plants for the remote arid areas with small water demands is viable due to the elimination of the high cost of the water transportation, and the connection to the electricity grid. The purpose of this paper is to review the technology, energy, and cost of the recent available desalination systems and their potential to be integrated with the renewable energy resources. This review suggests that the solar still distillation (SD) system, which is simply a natural evaporation-condensation process, is the most practical renewable desalination technique to be used in the remote arid areas; however, a further research is required to enhance their performance and to increase the productivities of these systems

Evaporation, seepage and water quality management in storage dams: a review of research methods

One of the most significant sources of water wastage in Australia is loss from small storage dams, either by seepage or evaporation. Over much of Australia, evaporative demand routinely exceeds precipitation. This paper outlines first, methodologies and measurement techniques to quantify the rate of evaporative loss from fresh water storages. These encompass high-accuracy water balance monitoring; determination of the validity of alternative estimation equations, in particular the FAO56 Penman- Monteith ETo methodology; and the commencement of CFD modeling to determine a 'dam factor' in relation to practical atmospheric measurement techniques. Second, because the application of chemical monolayers is the only feasible alternative to the high cost of physically covering the storages to retard evaporation, the use of cetyl alcohol-based monolayers is reviewed, and preliminary research on their degradation by photolytic action, by wind break-up and by microbial degradation reported. Similarly, preliminary research on monolayer visualisation techniques for field application is reported; and potential enhancement of monolayers by other chemicals and attendant water quality issues are considered

Internal Insulation of Historic Buildings: A Stochastic Approach to Life Cycle Costing Within RIBuild EU Project

The application of internal insulation is a widespread and effective solution for energy renovation of historic buildings.However, it entails quite high installation costs and a certain risk of failure due to moisture-related problems. A probabilistic risk assessment of both hygrothermal performance and life cycle costs can be used to address internal insulation issue, in order to support riskmanagement and decisionmaking. This paper presents the application of a probabilistic approach to Life Cycle Costing developed within the EU project RIBuild (Robust Internal Thermal Insulation of Historic Buildings), to five internal insulations solutions widely used in Italy. The method provides estimates of the range and likelihood of global costs and payback periods, also considering alternative energy and future economic scenarios. The impact of insulation systems service life on global costs is also addressed, in order to highlight the possible connection of the method to a stochastic estimation of insulation systems durability based on hygrothermal and damage assessments

Energy usage reduction in supermarket refrigerated food cabinets

Minimizing energy usage has always been a major aspect of the engineering design. Because of the increase in the expectations of the well-off population in the world for more comfort and convenience, the usage of energy has increased dramatically. A major usage of energy is in transport, air-conditioning, and refrigeration. The current changing of weather patterns, such as more frequent cyclones, floods, and extreme temperatures, which some believe is due to global warming and caused by our excessive usage of energy that releases greenhouse emissions, urges us to take a stand on reducing our energy usage and hence our carbon footprint. This entry will concentrate on how to reduce the energy usage in refrigerated food cabinets in supermarkets. It will present three phases in which attention to detail and usage of recent research findings can make a big difference. These are the design phase, the commissioning phase, and the maintenance phase. This entry also briefly presents some introductory information on the different commercial refrigeration systems and the basics of refrigeration

Cooling towers

Cooling is necessary to many industrial processes, such as power generation units; refrigeration and air conditioning plants; and the manufacturing, chemical, petrochemical, and petroleum industries. As recently as 20 years ago, cooling towers were more the exception than the rule in the industry because of their high operating cost and the large capital required for their construction. Due to the recent stringent environmental protections, cooling towers became more common. Cooling towers range in sizes and types. Wet, dry, and hybrid are the main types, and each type has many variations in design according to the way the fluids are moved through the system. Some of the advantages and disadvantages of these types, methods of determining their performance, and some terminology common to the cooling industry are presented in this entry

Numerical simulation of open refrigerated display cabinets

Open refrigerated display cabinets are becoming more widespread since they are believed to enhance sales by providing easy access to the chilled products. Air curtains are used as a barrier between the warm ambient air and the chilled compartment of the fridge. The effectiveness of the air curtain depends on many parameters. The objective of this work is to study the effect of jet velocity, turbulence intensity and temperature on the performance of a commercial refrigerated display cabinet aiming at minimizing energy usage. A 2-D numerical model suing double precision was solved using the computational software 'Fluent' that include the full buoyancy effect and radiation between surfaces. Results include temperature variations, estimation of the entrainment of air into the fridge and heat exchanged with the ambient air in the room. The numerical results indicate that jets with lower velocities at colder temperature enhance the efficiency of the open fridge. A reduction of 19.5 percent in the air entrainment and 23 percent in the heat gain was observed in comparison with the current setting. Temperature measurements and flow visualization using smoke were conducted to validate the numerical simulation

Numerical modelling of air temperature and velocity in a forced ventilation piggery

Pigs are subjected to intensive environment control and management for higher productivity due to their sensitivity to climatic variation, which affects their growth. The aim of the current work is to numerically model the air speed and temperature in a forced ventilation piggery to achieve optimum environmental control. This work can also help to identify problems in the design of piggeries and offer suggestions for improvements. A steady two-dimensional numerical model including the effect of buoyancy, turbulence and heat generated by the pigs was solved using the computational fluid dynamics software Fluent, using the integral volume method. Air speed and temperature inside the piggery and at the pigs’ level were predicted for three different locations of ventilation opening, inlet velocities in the range (0.3 - 7 m/s), insulation or no insulation in the external walls, and for 5 °C and 32 °C ambient temperatures

Optimization of the ventilation system for a forced ventilation piggery

Pigs are subjected to intensive environment control and management in order to achieve higher productivity. This is due to their sensitivity to climatic variation, which strongly affects their growth. This paper reports the design optimization of a forced ventilation piggery using computational fl uid dynamics. This numerical investigation determined the effect of varying the number of ventilation openings and their location on the air fl ow pattern, speed, temperature, power needed, ability to remove heat and residence time. The effect of varying the ventilation rate in a range (0.05 – 0.8 m3/s), and ambient temperatures of 5°C and 32°C was also investigated. The modeled piggery has dimensions 40 m × 15 m × 2.6 m, with central walkway and gable roof with the apex at 3.9 m and is a common design in Australia. A steady-state two-dimensional numerical model based on the integral volume method, including the effects of buoyancy and heat generated by the pigs, was solved using the computational fl uid dynamics software “Fluent.” Four designs were investigated and an optimum design, which facilitates better ventilation of the majority of the room, has been identifi ed. In summer, an inlet velocity has been recommended which achieves optimum environment inside the piggery meeting the pigs’ thermal comfort criteria with minimum power usage. During winter it became obvious that heating has to be used in all designs to be able to meet the pigs’ thermal comfort criteria

Numerical modelling of air temperature and velocity in a forced and free ventilation piggery

Pigs are subjected to intensive environment control and management for higher productivity due to their sensitivity to climatic variation, which affects their growth. The aim of the current work is to numerically model the air speed and temperature in forced and free ventilation piggeries to achieve optimum environmental control. A steady twodimensional numerical model including the effect of buoyancy, turbulence and heat generated by the pigs was solved using the computational fluid dynamics software Fluent, which is based on the integral volume method. In the forced ventilation case, air speed and temperature inside the piggery and at the pigs' level were predicted for three different locations of ventilation opening, variable air inlet velocities (in the range 0.3 mls - 7 mls), and insulated or non insulated external walls, for ambient temperatures of 5°c and 32°C. In the free ventilation case, temperature and air speed at the pig's level were predicted for a particular wind speed and direction, and some variations in the design. These variations were adding louvers in the air opening, lowering the outer wall of the piggery and changing the type of pen fence used. These results helped to identify problems in the design and offer suggestions for improvements

Inertisation of highwall mining to control methane concentrations at the Moura mine

Methane, a highly explosive gas, which is released during coal mining, presents an imminent problem when mixed with oxygen in regard to maintaining safe working conditions. The Moura Mine's previous highwall coal mining operation in Central Queensland identified that production rates and penetration depths of mining equipment has been restricted for mines with high methane concentrations in comparison to regions with lower methane concentrations. A number of inert gases have been identified to inertise the highwall drive, including Carbon Dioxide, Nitrogen and Boiler Gas, which is a combination of carbon dioxide, oxygen and nitrogen. The objective of this paper is to determine which of these gases is the most effective in improving the mine's efficiency with regard to safety and production rates at a chosen penetration depth of 300m. A 2D, steady, non-reacting species transport model of the highwall drive was used to obtain methane and oxygen concentrations using CFD software (Fluent). Results indicate that applying the inert gases at high angles is more effective in minimising the methane/oxygen concentrations within the drive than at lower angles. Carbon Dioxide was the most effective when applied at a 60 degree angle, followed closely by Nitrogen, while Boiler Gas came last