Structure of Optimal Transport Networks Subject to a Global Constraint

The structure of pipe networks minimizing the total energy dissipation rate is studied analytically. Among all the possible pipe networks that can be built with a given total pipe volume (or pipe lateral surface area), the network which minimizes the dissipation rate is shown to be loopless. Furthermore, such an optimal network is shown to contain at most N-2 nodes in addition to the N sources plus sinks that it connects. These results are valid whether the possible locations for the additional nodes are chosen freely or from a set of nodes (such as points of a grid). Applications of these results to various physical situations and to the efficient computation of optimal pipe networks are also discussed

Superstructure optimisation of a water minimisation network with a embedded multicontaminant electrodialysis model

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering, 2016The water-energy nexus considers the relationship between water and energy resources. Increases in environmental degradation and social pressures in recent years have necessitated the development of manufacturing processes that are conservative with respect to both these resources, while maintaining financial viability. This can be achieved by process integration (PI); a holistic approach to design which emphasises the unity of processes. Within the realm of PI, water network synthesis (WNS) explores avenues for reuse, recycle and regeneration of effluent in order to minimise freshwater consumption and wastewater production. When regeneration is required, membrane-based treatment processes may be employed. These processes are energy intensive and result in a trade-off between water and energy minimisation, thus creating an avenue for optimisation. Previous work in WNS employed a black box approach to represent regenerators in water minimisation problems. However, this misrepresents the cost of regeneration and underestimates the energy requirements of a system. The aim of the research presented in this dissertation is to develop an integrated water regeneration network synthesis model to simultaneously minimise water and energy in a water network. A novel MINLP model for the design of an electrodialysis (ED) unit that is capable of treating a binary mixture of simple salts was developed from first principles. This ED model was embedded into a water network superstructure optimisation model, where the objective was to minimise freshwater and energy consumption, wastewater productions, and associated costs. The model was applied to a pulp and paper case study, considering several scenarios. Global optimisation of the integrated water network and ED design model, with variable contaminant removal ratios, was found to yield the best results. A total of 38% savings in freshwater, 68% reduction in wastewater production and 55% overall cost reduction were observed when compared with the original design. This model also led to a 80% reduction in regeneration (energy) cost.GS201

Cost Minimization Model of Gas Transmission Line for Indonesian SIJ Pipeline Network

Optimization of Indonesian SIJ gas pipeline network is being discussed here. Optimum pipe diameters together with the corresponding pressure distribution are obtained from minimization of total cost function consisting of investment and operating costs and subjects to some physical (Panhandle A and Panhandle B equations) constraints. Iteration technique based on Generalized Steepest-Descent and fourth order Runge-Kutta method are used here. The resulting diameters from this continuous optimization are then rounded to the closest available discrete sizes. We have also calculated toll fee along each segment and safety factor of the network by determining the pipe wall thickness, using ANSI B31.8 standard. Sensitivity analysis of toll fee for variation of flow rates is shown here. The result will gives the diameter and compressor size and compressor location that feasible to use for the SIJ pipeline project. The Result also indicates that the east route cost relatively less expensive than the west cost

Cost Minimization Model of Gas Transmission Line for Indonesian SIJ Pipeline Network

Optimization of Indonesian SIJ gas pipeline network is being discussed here. Optimum pipe diameters together with the corresponding pressure distribution are obtained from minimization of total cost function consisting of investment and operating costs and subjects to some physical (Panhandle A and Panhandle B equations) constraints. Iteration technique based on Generalized Steepest-Descent and fourth order Runge-Kutta method are used here. The resulting diameters from this continuous optimization are then rounded to the closest available discrete sizes. We have also calculated toll fee along each segment and safety factor of the network by determining the pipe wall thickness, using ANSI B31.8 standard. Sensitivity analysis of toll fee for variation of flow rates is shown here. The result will gives the diameter and compressor size and compressor location that feasible to use for the SIJ pipeline project. The Result also indicates that the east route cost relatively less expensive than the west cost

The Exchange Value Embedded In A Transport System

This paper shows that a well designed transport system has an embedded exchange value by serving as a market for potential exchange between consumers. Under suitable conditions, one can improve the welfare of consumers in the system simply by allowing some exchange of goods between consumers during transportation without incurring additional transportation costs. We propose an explicit valuation formula to measure this exchange value for a given compatible transport system. This value is always nonnegative and bounded from above. Criteria based on transport structures, preferences and prices are provided to determine the existence of a positive exchange value. Finally, we study a new optimal transport problem with an objective taking into account of both transportation cost and exchange value.Comment: 20 pages, 6 figure

Synthesis and Design Strategies for the Development of Macroscopic Interplant Water Networks in Industrial Zones

Increased water scarcity problems, coupled with the immense scale of water-intensive industrial activities in the region demands for the development of optimal water reuse and recycling strategies in industrial cities. Hence, industrial water and wastewater management is a key research priority. As a result, several necessary aspects that have not been addressed previously in water integration methods have been considered in this work, by developing and implementing a framework which allows for improved applications of macroscopic water integration in complex industrial regions. The main components relevant to the planning of cost-effective water networks in a devised city plan have been captured with a focus on identifying cost-effective water allocations within an industrial city. Detailed information associated with water-using and water-consuming entities have been captured, using both flowrate and contamination information as well as site location information. Hence, a spatial representation that is capable of capturing an industrial city arrangement, has been developed to assist in water network design, an aspect which has often been overlooked in existing methods. Moreover, the presence of a number of different options during the selection process of appropriate treatment technologies, as well as the efficient placement of corresponding treatment facilities, have also been considered. In addition to the above aspects, two different pipeline merging representations that are capable of identifying cost-effective opportunities have also been captured in this work. Both approaches allow for the screening of less complex pipeline networks, by assembling together commonly existing pipe sections, in the course of determining optimal water networks. All methods were implemented and demonstrated using several industrial city layout scenarios, and each method was able to identify a number of optimal synergies

An Integrated Network Architecture for a High Speed Distributed Multimedia System.

Computer communication demands for higher bandwidth and smaller delays are increasing rapidly as the march into the twenty-first century gains momentum. These demands are generated by visualization applications which model complex real time phenomena in visual form, electronic document imaging and manipulation, concurrent engineering, on-line databases and multimedia applications which integrate audio, video and data. The convergence of the computer and video worlds is leading to the emergence of a distributed multimedia environment. This research investigates an integrated approach in the design of a high speed computer-video local area network for a distributed multimedia environment. The initial step in providing multimedia services over computer networks is to ensure bandwidth availability for these services. The bandwidth needs based on traffic generated in a distributed multimedia environment is computationally characterized by a model. This model is applied to the real-time problem of designing a backbone for a distributed multimedia environment at the NASA Classroom of the Future Program. The network incorporates legacy LANs and the latest high speed switching technologies. Performance studies have been conducted with different network topologies for various multimedia application scenarios to establish benchmarks for the operation of the network. In these performance studies it has been observed that network topologies play an important role in ensuring that sufficient bandwidth is available for multimedia traffic. After the implementation of the network and the performance studies, it was found that for true quality of service guarantees, some modifications will have to be made in the multimedia operating systems used in client workstations. These modifications would gather knowledge of the channel between source and destination and reserve resources for multimedia communication based on specified requirements. A scheme for reserving resources in a network consisting legacy LAN and ATM is presented to guarantee quality of service for multimedia applications

All season heat pipe system.

Our energy choices impact the earth’s natural systems and climate. As this becomes increasingly important, the need for decreasing our energy usage is essential. Conventional passive solar systems can significantly reduce the heating load. Similarly, passive ambient energy systems, such as ventilation and sky radiation, can reduce cooling loads. However, the integration of passive heating and cooling systems in the same building and the benefits of actively controlling these otherwise passive systems to maximize annual energy savings has largely been unexplored. This study first evaluates the building cooling capacity of sky radiation, which was previously identified to have the greatest cooling potential among common ambient sources for climates across the U.S., and the design parameters of the system. Next, the study develops and varies the control strategies of a passive heating and cooling system with the objective of maximizing annual energy and cost savings. The systems were simulated with thermal networks using Matrix Laboratory (MATLAB), a computer software package. Nodal temperatures were simultaneously solved as functions of time using Typical Meteorological Year (TMY3) weather data. Auxiliary heating and cooling were added as needed to limit room temperature to a maximum of 23.9 ˚C and minimum of 18.3 ˚C. Results were compared to a Louisville baseline with LRR = 10 W/m2K, horizontal radiator and one cover, which provided an annual sky fraction (fraction of cooling load provided by sky radiation) of 0.855. A decrease to 0.852 was found for an increase in radiator slope to 20˚, and a drop to 0.832 for 53˚ slope (latitude + 15˚, a typical slope for solar heating). These drops were associated with increases in average radiator temperature by 0.73˚C for 20˚ and 1.99˚C for 53˚. A 30% decrease in storage capacity caused a decrease in sky fraction to 0.843. LRR and thermal storage capacity had strong effects on performance. Radiator slope had a surprisingly small impact, considering that the view factor to the sky at 53˚ tilt is less than 0.5. Chapter 3 expanded on and analyzed the design of the windscreen for the sky radiator used for cooling as well as the effects of implementing the heat pipe augmented sky radiator to varying climates. When applying a windscreen of polyethylene, which is mostly transparent to long-wave radiation, a drawback of polyethylene is its susceptibility to degradations of the optical properties. Sky fractions of 100% were possible in cities with small cooling loads (Rock Springs, Seattle, San Diego and Denver). Sky fractions of over 50% were achieved in New Orleans and Houston and over 40% in Miami. A second study examined the degradation of polyethylene cover material. Louisville and two challenging climates (Miami and New Orleans) were simulated. In the Louisville, Miami and New Orleans climate, performance was reduced by 2.7%, 14.1% and 9.0% respectively, due to degradation of the cover’s material. Chapter 4 explores the combination of a solar heating heat pipe system and sky radiation heat pipe cooling system. Two configurations were modeled in the Louisville, KY climate. The first system configuration, called a Separate System (SS), consists of a sky radiator and thermal mass that are separate from a solar heat pipe system and its thermal mass. The second system configuration, called a Combined System (CS), utilizes a shared thermal mass between the solar absorber and sky radiator. The control strategies simulated included: Seasonal, Ambient, Room and Matrix. The highest fraction of energy supplied by ambient sources for the SS was 0.707 with Matrix control, while for the CS, the highest fraction (0.704) was with Matrix temperature control with switchable attributes for heating and cooling. In Chapter 5, the two configurations in Chapter 4 were simulated with additional active control approaches. The four control strategies in Chapter 5 included variables: ambient temperature (current and forecasted), indoor air temperature, calculated auxiliary load and heating/cooling (current and forecasted) load. The highest ambient energy fractions (fraction of the total annual load served by the system) of the configurations using a SS for Louisville were 0.710, 0.708, 0.715 and 0.712 respectively. With an estimated cost savings of $49-$54/m2 USD for the Louisville baseline climate using a SS. The ambient energy fraction only decreased by 1% for the CS (AUX-24HR ambient energy fraction of 0.709)

Generic sensor network architecture for wireless automation (GENSEN)

fi=vertaisarvioimaton|en=nonPeerReviewed

Application of Computational Fluid Dynamics Methods to Improve Thermal Hydraulic Code Analysis

A computational fluid dynamics code is used to model the primary natural circulation loop of a proposed small modular reactor for comparison to experimental data and best-estimate thermal-hydraulic code results. Recent advances in computational fluid dynamics code modeling capabilities make them attractive alternatives to the current conservative approach of coupled best-estimate thermal hydraulic codes and uncertainty evaluations. The results from a computational fluid dynamics analysis are benchmarked against the experimental test results of a 1:3 length, 1:254 volume, full pressure and full temperature scale small modular reactor during steady-state power operations and during a depressurization transient. A comparative evaluation of the experimental data, the thermal hydraulic code results and the computational fluid dynamics code results provides an opportunity to validate the best-estimate thermal hydraulic code\u27s treatment of a natural circulation loop and provide insights into expanded use of the computational fluid dynamics code in future designs and operations. Additionally, a sensitivity analysis is conducted to determine those physical phenomena most impactful on operations of the proposed reactor\u27s natural circulation loop. The combination of the comparative evaluation and sensitivity analysis provides the resources for increased confidence in model developments for natural circulation loops and provides for reliability improvements of the thermal hydraulic code