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• Techniques for heat integrated water allocation network synthesis are reviewed. • Pinch analysis, mathematical programming, and hybrid approaches are compared. • The research progress is highlighted through a case study. • Significant contributions are emphasized and future directions are provided. Heat integrated water allocation networks (HIWANs) were developed to conserve energy and water in the process industry using heat exchangers, and in some cases with water regeneration units. This paper addresses the challenges in optimizing HIWANs posed by the interactions between the water, energy, regeneration units, and heat exchangers. The optimization strategies are classified based on the adopted ideologies, and the progress in each category is discussed. A case study is examined to highlight the effect of adopting various strategies on the optimal solution. It is observed that the research progresses from the conservation of resources and operating costs to the inclusion of investment costs. More recent papers include studies that capture the trade-offs between freshwater, regeneration, utilities, and heat exchangers. The analysis of publications in different conferences and peer-reviewed journals is performed. After a detailed review of the existing work, some areas of improvement and new research perspectives are identified. [ABSTRACT FROM AUTHOR]

Energy and water resources are conserved simultaneously by optimizing heat integrated water conservation networks using numerical optimization or Pinch Analysis tools. Although numerical optimization provides a general framework, it does not impart physical insights into the problem. In contrast, Pinch Analysis tools enhance the visualization but cannot handle complexities. This paper combines the benefits of Pinch Analysis with numerical optimization to develop an algorithm to minimize the total annualized cost through a hybrid approach. The proposed algorithm comprises two linear programming models, minimizing the water and thermal energy requirement. A novel heuristic is proposed in this paper to incorporate non-isothermal mixing within a linear programming framework. Once the non-isothermal mixing streams are identified, the thermal energy consumption, heat exchanger area, and the number of heat exchanger units are minimized through Pinch Analysis. The proposed algorithm targets water, thermal energy, and heat exchanger requirements ahead of the system's design. The efficacy of the proposed algorithm is illustrated through two examples from the literature. The proposed algorithm provides results that are either superior to (e.g., 18% reduction in total annualized costs) or at par with the numerical optimization techniques, which require models with integer variables and non-linearities to be solved. [Display omitted] • A hybrid solution strategy is proposed for heat integrated water conservation network. • The proposed approach combines linear programming with Pinch Analysis. • Heuristic-based linear programming incorporates non-isothermal mixing. • The proposed algorithm targets the total annualized cost ahead of the design. [ABSTRACT FROM AUTHOR]

To address climate change issues and achieve sustainable industrial developments, process industries aim to conserved water and energy, two utmost essential resources. In the optimal design of thermally integrated water conservation networks, energy and water are conserved simultaneously. In the literature, various methods were proposed to identify a single optimal solution. However, to consider factors such as space constraints, topological constraints, uncertainties associated with the cost of the utilities, availability of water and energy, etc., all the potentially optimal solutions should be explored. In this paper, these optimal configurations are identified by portraying the trade-offs between the water and the energy requirements by extending the bi-objective Pinch Analysis framework. The interactions between the freshwater and the thermal utility requirements in a heat integrated water conservation network are established through the Pareto-optimal front. Four illustrative examples from the literature are solved and compared to exhibit the efficacy of the developed method. In one example, an increase in water consumption by 3% reduced the energy requirements by 30% and eliminated the need for a cooling tower. However, such a solution may not be preferred in regions of water scarcity, and other options can be explored through the Pareto-optimal front. The proposed algorithm is computationally efficient in representing potential trade-offs between energy and water requirements in thermally integrated water conservation networks. [Display omitted] • Proposed method simultaneously optimizes freshwater and hot utility requirements. • Efficient solutions of the bi-objective problem are depicted on the Pareto front. • Bi-objective Pinch Analysis is applied to identify efficient solutions. • Efficacy of the proposed method is established through examples from the literature. [ABSTRACT FROM AUTHOR]