Exergy-Based Design and Analysis of Heat Exchanger Networks

Exergy analysis of multiple heat exchanger networks: An approach based on the irreversibility distribution ratio

Chapter 10 Pinch point analysis

Optimal assignment of multiple utilities in heat exchange networks

Styrene is an organic compound used for the synthesis of polymers, co-polymers, and rubber. Generally, the reaction to form styrene comes from the dehydrogenation of ethylbenzene. This reaction occurs when the compound is in the vapor phase and is endothermic. One of the technologies for ethylbenzene dehydrogenation is Lummus/UOP Smart SM. This technology uses oxygen to heat the reaction and makes the hydrogen disappear, so the reacting reaches the highest ethylbenzene conversion. The focus of this research was pinch analysis on Lummus/UOP Smart SM. The first step in pinch analysis is data extraction. An alternative is to perform pinch analysis with a composite curve, problem table, shifted composite curve, and grand composite curve. Then is continued to create a design Heat Exchanger Network (HEN). The application of pinch analysis to evaluate heating duty, cooling duty, Maximum Energy Recovery (MER), and determine the exact HEN for optimal energy. In this research, the integration of the process showed not optimal results, especially in cooling duty, because the energy recovery was obtained small, and for heating duty saved about 14%.

Ventilation heat loss is one of the most important factors contributing to energy performance of greenhouses. This paper suggests a systematic method based on dynamic pinch analysis (PA) to design an integrated heating, cooling, and ventilation system that uses ventilation waste heat in a cost-effective and energy efficient way. A heat recovery system including an air handling unit, borehole thermal storage, and a heat pump is proposed to investigate all heat integration scenarios for an entire year. In the first step, the heat integration scenarios are reduced to a few typical days using a clustering technique. Then, a generic methodology for designing a heat exchanger network (HEN) for a dynamic system, ensuring both direct and indirect heat recovery, is presented and a set of HENs are designed according to the conditions of typical days. Afterwards, the best HEN design is selected among all design alternatives using a techno-economic analysis. The whole procedure is applied to a commercial greenhouse and the best HEN configuration and required equipment sizes are calculated. It is shown that the best-performing design for the greenhouse under study produces primary energy savings of 57%, resulting in the shortest payback period of 9.5 years among all design alternatives.

Coupling Refrigeration System Synthesis and Heat Exchanger Network Design

Improved optimization strategies for automated heat exchanger network synthesis through physical insights

A combined numerical and visualization tool for utility targeting and heat exchanger network retrofitting

Work and heat integration: An emerging research area

Targeting the maximum heat recovery for systems with heat losses and heat gains

The integration of expanders into heat exchanger networks (HENs) is a complex task since both heat and work are involved. In addition, the role of streams (as hot or cold), the utility demand, and the location of pinch points may change. With certain well‐defined conditions, four theorems are proposed for the integration of expanders into HENs above ambient temperature with the objective of minimizing exergy consumption. A straightforward graphical methodology for above ambient HENs design including expanders is developed on the basis of Grand Composite Curves (GCCs). It is concluded that to achieve a design with minimum exergy consumption, stream splitting may be applied and expansion should be done at pinch temperatures, hot utility temperature, or ambient temperature. In the majority of cases, however, and in line with the concept of Appropriate Placement from Pinch Analysis, expansion at pinch temperatures gives the minimum exergy consumption. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3404–3422, 2015

A novel Heat Exchanger Network Bridge Retrofit method using the Modified Energy Transfer Diagram

Fouling and aging are the main causes for the degradation of heat exchanger performance from a well-behaved heat-transfer performance. They result in extra capital and energy costs for heat exchanger networks (HENs) to compensate for the gap in target temperatures. To reduce the negative effect of deposition, this paper presents a novel methodology for managing the cleaning schedule problem in the design of HENs. The method consists of three steps. First, obtain an original HEN using pseudotemperature enthalpy diagram approach. Then, simplify the structure of the original HEN through loop-breaking and small size unit eliminating strategies. Finally, optimize heat-transfer areas and cleaning schedules by considering the growth of deposits via a mixed integer nonlinear programming model. Therefore, the model is capable of weighing the capital cost for exchangers and the operation cost for both utility consumption and cleaning activities. In this study, two off-line cleaning alternatives with distinct cleaning efficiencies are provided for deposition removal; therefore, the problem of which method should be selected for each exchanger will also be investigated in the model. At the end of the study, an illustrative example is presented to demonstrate the proposed method. The results have indicated the potential for cost savings when good cleaning schedules are planned with the design of HENs.

Heat Exchanger Network Design Considering Inherent Safety

Improving energy efficiency in a complex natural gas refinery using combined pinch and advanced exergy analyses