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Mahmoud M. El-halwagi - One of the best experts on this subject based on the ideXlab platform.

  • Multi-scenario model for optimal design of seawater air-conditioning systems under demand uncertainty
    Journal of Cleaner Production, 2019
    Co-Authors: Ilse María Hernández-romero, Mahmoud M. El-halwagi, Rajib Mukherjee, Medardo Serna-gonzález, Luis Fabián Fuentes-cortés, Fabricio Nápoles-rivera
    Abstract:

    Abstract Seawater air conditioning (SWAC) systems use deep seawater as a Cooling Utility. SWAC systems are receiving increasing attention as an integral component of sustainable Cooling units of lodging complexes because of the availability of seawater, the substitution of chemicals refrigerants, low achievable temperature, low environmental impact, and large potential savings in energy consumption compared to conventional air-conditioning systems. The design of these systems depends mainly on the energy demand of each hotel in each month; however, there is uncertainty in this variable, since it depends on the season of the year, being lower in months of low occupancy and higher in months of high tourist occupancy. This paper presents a multi-objective optimization with a probabilistic formulation approach for designing these systems under seasonal energy demand uncertainty. The model seeks to meet the demands of air conditioning in hotels using deep seawater considering technical aspects and seeks to minimize the total annual cost while minimizing emissions of greenhouse gases. The results show the importance of accounting uncertainty in the design of these systems.

  • Optimal design of air-conditioning systems using deep seawater
    Clean Technologies and Environmental Policy, 2018
    Co-Authors: Ilse María Hernández-romero, Fabricio Nápoles-rivera, Rajib Mukherjee, Medardo Serna-gonzález, Mahmoud M. El-halwagi
    Abstract:

    This paper presents a multi-objective mixed integer linear programming problem for the optimization of seawater air-conditioning systems using deep seawater as a Cooling Utility. The optimization formulation was developed including the technical, economic and environmental aspects of the problem. The model is used to define the optimal scheduling of deep seawater use and electricity needed to satisfy the air-conditioning requirements in a group of hotels. It also addresses the optimal planning for biocide, neutralization chemical dosing and mechanical maintenance required to maintain optimal operation conditions in the system. The proposed model is applied to a case study in Mexico. Results show the trade-offs between economic and environmental aspects. Optimal solutions compensating economic and environmental objectives are identified through a Pareto front.

  • Mathematical Techniques for the Synthesis of Heat-Exchange Networks
    Sustainable Design Through Process Integration, 2017
    Co-Authors: Mahmoud M. El-halwagi
    Abstract:

    Chapter 7, Heat Integration, provided graphical and algebraic procedures for the synthesis of heat-exchange networks (HENs). This chapter presents a mathematical-programming approach to the synthesis of HENs. First, the HEN formulation will be presented and solved to attain minimum heating and Cooling Utility cost and selecting the optimum utilities. Next, a formulation is presented to synthesize a network of heat exchangers that can meet the minimum Utility targets. The optimization formulations in this chapter are based on the transshipment formulation of Papoulias and Grossmann. Numerous other methods have been developed for the synthesis of HENs. These methods have been reviewed by Smith, Luo et al., Klemes and Kravanja, Klemes, Noureldin, Rossiter, Majozi, Kemp, Ponce-Ortega et al., Al-Thubaiti et al., Furman and Sahinidis, Shenoy, Linnhoff, and Gundersen and Naess.

  • Simultaneous synthesis of Utility system and heat exchanger network incorporating steam condensate and boiler feedwater
    Energy, 2016
    Co-Authors: Xianglong Luo, Jos?? Mar??a Ponce-Ortega, Xiaojian Huang, Mahmoud M. El-halwagi, Ying Chen
    Abstract:

    A heat exchanger network (HEN) is an important part in processing plants used to recover heat from process streams. A Utility system supplies heating and Cooling utilities and introduces additional hot and cold streams for the processes. The HEN and Utility system (e.g., Rankine cycle-based cogeneration system) are closely interconnected primarily through steam, steam condensate leaving the turbines, and process surplus heat. The recovery of the sensible heat from the steam condensate and process surplus heat through an integration technique may contribute significantly to the reduction of the heating and Cooling Utility consumption in the heat exchanger network as well as in the primary energy consumption in the Utility system. In this paper, a systematic methodology for the simultaneous synthesis and design of a Utility system and HEN is proposed. The heat recovery from the steam condensate and boiler feedwater preheating are integrated into the HEN synthesis together with the design optimization of a Rankine cycle-based Utility system. In addition to the simultaneous design of the Utility and heat-recovery systems, the optimization variables include the steam condensate target temperature, the steam level for process heating, the energy demand for the Utility system, the returning temperature of the steam condensate, and the final temperature of the boiler feed water. The total site HEN is composed of several interlinked sub-HENs. A model for the new hot Utility-process cold stream HEN is formulated together with the hot -cold process streams of the HEN. The linking constraints between sub-HENs and the Utility system are formulated. Several case studies are elaborated to demonstrate the effectiveness and applicability of the proposed methodology. Compared with the former design methods without integrating steam condensate sensible heat and boiler feedwater preheating, meaningful economic benefits can be achieved by applying the proposed framework.

  • Integration of Thermal Membrane Distillation Networks with Processing Facilities
    Industrial & Engineering Chemistry Research, 2013
    Co-Authors: Nesreen A. Elsayed, Maria A. Barrufet, Mahmoud M. El-halwagi
    Abstract:

    Thermal membrane distillation (TMD) is an emerging technology which is gaining an increasing level of interest in the area of high-purity separation especially in water treatment. It is driven primarily by heat which creates a vapor-pressure difference across a porous hydrophobic membrane. The integration of TMD with industrial processes offers several advantages. Excess low-level heat from the process can be used to drive TMD. This transfer of heat also reduces the Cooling Utility load for the process. Therefore, dual heat-reduction benefits accrue as a result of this heat integration. Additionally, process wastewater and Utility water may be treated using TMD then recycle or reused in the process or sold to external users. This paper introduces a process integration framework from the thermal coupling of TMD networks and industrial processes. First, a three-parameter model is developed to quantify the water flux through the membranes as a function of heat and temperature. The model is validated using ex...

Guilian Liu - One of the best experts on this subject based on the ideXlab platform.

  • Energy recovery enhancement of heat exchanger network by mixing and azeotrope formation
    Chemical Engineering Science, 2020
    Co-Authors: Di Zhang, Huifeng Sun, Guilian Liu
    Abstract:

    Abstract Mixing two streams with different components and/or compositions could enhance heat recovery if they contain azeotrope-forming components. This study investigates the integration of Heat Exchanger Network (HEN) considering mixing and azeotrope formation. Two cold streams are mixed to form a minimum azeotropic mixture and vaporised. Variations in heat capacity flowrate, net heat flow, and Grand Composite Curve are analysed, and their quantitative relations and Utility consumption are deduced. Principles behind mixing and azeotrope formation are clarified to enhance energy recovery. A styrene production process is studied using the proposed method. With steam condensate mixed with ethylbenzene and vaporised at the azeotropic composition, the minimum heating and Cooling Utility consumption can be reduced by 22.87% and 13.88%.

  • Integration of heat exchanger network considering the pressure variation of distillation column
    Applied Thermal Engineering, 2017
    Co-Authors: Di Zhang, Guilian Liu
    Abstract:

    Abstract The pressure variation of distillation column causes the temperature variation of some sinks or sources of the Heat Exchanger Network (HEN). A graphical method is proposed to analyze this problem, with the inflection point of composite curve shifted. Rules are proposed for identifying the minimum heating and Cooling Utility without plotting the composite curves, as well as the variation of the pinch. The proposed method can be applied to design and retrofit industrial processes.

  • Integration of Heat Exchanger Network Considering the Influence of the Reactor
    Chemical engineering transactions, 2016
    Co-Authors: Di Zhang, Guilian Liu
    Abstract:

    Integrating the Heat Exchanger Network (HEN) by Pinch Technology is an efficient method to decrease energy consumption. In a HEN, some source and sink streams, and their heating and Cooling duties are dictated by the reactor. Hence, the reactor design affects the integration of HEN. There is the possibility to reduce the Utility further by adjusting the reactor design parameters. To achieve this, it is necessary to consider the influence of reactor on the HEN integration. In this work, a graphical method is proposed to analyze the effect of the reactor’s uncertainty of VGO hydrotreating process. Since the variation of the reactor parameters affects the inlet and outlet streams’ target and/or supply temperature, the temperature variation of the corresponding source and sink is accommodated by shifting the corresponding inflection point of the composite curve. Correspondingly, the part of the composite curve below or above the inflection point is shifted to target the heating and/or Cooling Utility. When the operating parameter of the reactor changes, whether the pinch will change or not can be identified by the proposed method, as well as the minimum heating and Cooling utilities.

Jiří Jaromír Klemeš - One of the best experts on this subject based on the ideXlab platform.

  • Centralised Utility system planning for a Total Site Heat Integration network
    Computers & Chemical Engineering, 2013
    Co-Authors: Peng Yen Liew, Sharifah Rafidah Wan Alwi, Petar Sabev Varbanov, Zainuddin Abdul Manan, Jiří Jaromír Klemeš
    Abstract:

    Total Site Heat Integration (TSHI) is a technique of exchanging heat among multiple processes via a centralised Utility system. An analysis of the integrated multiple processes, also known as the Total Site (TS) system sensitivity, is needed to characterise the effects of a plant maintenance shutdown, to determine the operational changes needed for the Utility production and to plan mitigation actions. This paper presents an improved Total Site Sensitivity Table (TSST) to be used as a systematic tool for this purpose. The TSST can be used to consider various ‘what if’ scenarios. This tool can be used to determine the optimum size of a Utility generation system, to design the backup generators and piping needed in the system and to assess the external utilities that might need to be bought and stored. The methodology is demonstrated by using an Illustrated Case Study consisting of three processes. During the TS normal operation, the Total Site Problem Table Algorithm (TS-PTA) shows that the system requires 1065 kW of High Pressure Steam and 645.5 kW of Medium Pressure Steam as the heating Utility, while for the Cooling Utility, 553.5 kW of Low Pressure Steam and 3085 kW of Cooling water are required. The results of the modified TSST proposed that a boiler and a Cooling tower with the system design requiring a maximum capacity of 2.172 MW of steam and 4.1865 MW of Cooling water are needed to ensure an operational flexibility between the three integrated processes.

  • Water Integration for Recycling and Recovery in Process Industry
    Security of Industrial Water Supply and Management, 2011
    Co-Authors: Jiří Jaromír Klemeš, Loong Lam, Dominic C.y. Foo
    Abstract:

    Water is widely used in the process industries as an important raw material. It is also frequently used in the heating and Cooling Utility systems. Strict requirements for the products quality and the associated safety issues in manufacturing contribute to large amounts of high-quality water being consumed by the process industry. Environmental regulations as well as the growing human population with improved quality of life have led to the growing demand of good quality water. These changes have increased the need for improved water management and wastewater minimisation. The adoption of water minimisation techniques can effectively reduce both the fresh water demand and subsequently the effluent generation in the process industry. This results in the reduced cost for fresh water acquisition and effluent treatment. This paper presents a graphical water integration method based on Water Pinch Analysis. This method locates various network targets prior to detailed design. A case study is given to demonstrate how to synthesise a water network for maximum water recovery with this method.

Di Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Energy recovery enhancement of heat exchanger network by mixing and azeotrope formation
    Chemical Engineering Science, 2020
    Co-Authors: Di Zhang, Huifeng Sun, Guilian Liu
    Abstract:

    Abstract Mixing two streams with different components and/or compositions could enhance heat recovery if they contain azeotrope-forming components. This study investigates the integration of Heat Exchanger Network (HEN) considering mixing and azeotrope formation. Two cold streams are mixed to form a minimum azeotropic mixture and vaporised. Variations in heat capacity flowrate, net heat flow, and Grand Composite Curve are analysed, and their quantitative relations and Utility consumption are deduced. Principles behind mixing and azeotrope formation are clarified to enhance energy recovery. A styrene production process is studied using the proposed method. With steam condensate mixed with ethylbenzene and vaporised at the azeotropic composition, the minimum heating and Cooling Utility consumption can be reduced by 22.87% and 13.88%.

  • Integration of heat exchanger network considering the pressure variation of distillation column
    Applied Thermal Engineering, 2017
    Co-Authors: Di Zhang, Guilian Liu
    Abstract:

    Abstract The pressure variation of distillation column causes the temperature variation of some sinks or sources of the Heat Exchanger Network (HEN). A graphical method is proposed to analyze this problem, with the inflection point of composite curve shifted. Rules are proposed for identifying the minimum heating and Cooling Utility without plotting the composite curves, as well as the variation of the pinch. The proposed method can be applied to design and retrofit industrial processes.

  • Integration of Heat Exchanger Network Considering the Influence of the Reactor
    Chemical engineering transactions, 2016
    Co-Authors: Di Zhang, Guilian Liu
    Abstract:

    Integrating the Heat Exchanger Network (HEN) by Pinch Technology is an efficient method to decrease energy consumption. In a HEN, some source and sink streams, and their heating and Cooling duties are dictated by the reactor. Hence, the reactor design affects the integration of HEN. There is the possibility to reduce the Utility further by adjusting the reactor design parameters. To achieve this, it is necessary to consider the influence of reactor on the HEN integration. In this work, a graphical method is proposed to analyze the effect of the reactor’s uncertainty of VGO hydrotreating process. Since the variation of the reactor parameters affects the inlet and outlet streams’ target and/or supply temperature, the temperature variation of the corresponding source and sink is accommodated by shifting the corresponding inflection point of the composite curve. Correspondingly, the part of the composite curve below or above the inflection point is shifted to target the heating and/or Cooling Utility. When the operating parameter of the reactor changes, whether the pinch will change or not can be identified by the proposed method, as well as the minimum heating and Cooling utilities.

Nesreen A. Elsayed - One of the best experts on this subject based on the ideXlab platform.

  • Integration of Thermal Membrane Distillation Networks with Processing Facilities
    Industrial & Engineering Chemistry Research, 2013
    Co-Authors: Nesreen A. Elsayed, Maria A. Barrufet, Mahmoud M. El-halwagi
    Abstract:

    Thermal membrane distillation (TMD) is an emerging technology which is gaining an increasing level of interest in the area of high-purity separation especially in water treatment. It is driven primarily by heat which creates a vapor-pressure difference across a porous hydrophobic membrane. The integration of TMD with industrial processes offers several advantages. Excess low-level heat from the process can be used to drive TMD. This transfer of heat also reduces the Cooling Utility load for the process. Therefore, dual heat-reduction benefits accrue as a result of this heat integration. Additionally, process wastewater and Utility water may be treated using TMD then recycle or reused in the process or sold to external users. This paper introduces a process integration framework from the thermal coupling of TMD networks and industrial processes. First, a three-parameter model is developed to quantify the water flux through the membranes as a function of heat and temperature. The model is validated using ex...