Shankar Narasimhan S

Ensuring adequate supply of clean drinking water and electricity in several parts of the world continues to be a formidable challenge. In coastal areas facing this problem, desalination of sea water using Reverse Osmosis (RO) driven by solar power without batteries can be an appropriate technological solution. Variability in incident solar power is a significant operational issue. The focus of this work is optimal operation and control of the RO plant with guaranteed water purity. A steady state model is developed and validated using 'ROSA', a black-box software programme commonly used for simulating RO plants. Analysis of the optimal solution reveals that the feasible space (of available power) consists of two regions where different set of constraints are active. In one region salt concentration constraint is active and in another, the pressure constraint is active. Hence the optimal operation strategy can be implemented by active constraint control. © 2012 Elsevier B.V.

Optimal operation of municipal Water Distribution Networks (WDNs) is based on optimizing one or more performance metrics while meeting consumer demands and satisfying supply side and storage constraints. This can be achieved by implementing advanced control schemes such as Model Predictive Control (MPC). With the alarming decrease in fresh water supplies, the primary focus of online control strategies should be to conserve water. A novel control strategy that can handle both water sufficient and deficient cases is proposed for WDNs with storage facilities. Performance of the developed model based online control strategy is tested by numerical simulations of an illustrative WDN. © 2012 Elsevier B.V.

Seaborne trade in LPG or its constituents (liquid propane and butane) has been growing substantially and is projected to rise to 70 Mt by 2012. Loading LPG onto ship tankers, transporting and unloading LPG from tankers to inland terminals are time and energy intensive operations. The purpose of this study is to arrive at an optimal sequence of flow rates when unloading a given amount of LPG from the ship tanker to the inland storage tank. A distributed dynamic model accounting for heat transfer and fluid flow is developed. This model is used in a simulation based optimization framework to determine the optimal unloading sequence that minimizes material, demurrage and energy costs. © 2011 Elsevier B.V.

With the demand for water increasing rapidly, optimal operation of Water Distribution Networks (WDNs) is necessary to provide consumers with the maximum amount of water possible in an equitable manner. This paper presents the outcomes of an experimental investigation of supply policies implementable on rural WDNs. Tests conducted on a fully automated lab scale network, configured to represent rural WDNs, shows significant variations in supply time with the operational policy followed. Further, a systematic set of experiments are carried out to determine the flow rates in different network configurations and this data is later used to formulate a linear programming problem that identifies an optimal operational policy for the system.