Large-scale Heat Exchanger Research Articles

Research on large-scale microchannel heat exchangers in domestic heat pump air conditioning applications

Research on large-scale microchannel heat exchangers in domestic heat pump air conditioning applications

A novel optimization framework integrating multiple initialization, automatic topologization and MINLP reduction to accelerate large-scale heat exchanger network synthesis

Ensuring the solution feasibility and achieving an acceptable solution time for the non-deterministic polynomial-time hard (NP-hard) problem of heat exchanger network (HEN) synthesis is still challenging. In this study, we developed a novel optimization framework for efficiently solving large-scale HEN synthesis problems to obtain near global optimal solutions, simultaneously addressing the solution's infeasibility and time. The optimization framework consists of a multiple initial HEN design model (M-INI model), a new distance-based auto structure transformer (A-STR transformer), and a reduced non-linear programming model (R-NLP model). The M-INI model generates various HEN designs based on pinch analysis by varying the minimum approach temperature and the modes of stream splitting and mixing. The A-STR transformer is first proposed to automatically convert various HEN designs into associated superstructure-based topologies as multiple initial starting points for accelerating the solution of the R-NLP model. A strategy for approximating the temperature difference calculation is further applied to reduce the computational loads. Four case studies were conducted using the proposed method to minimize the total annual cost (TAC). The solutions of general cases 1 and 2 are almost equal to the best results in the literature, while the solution time is reduced by 98.7 % and 99.8 %, respectively, which demonstrates the performance of the proposed method. Especially, the method was applied to two practical industrial HEN cases: a large-scale low-grade heat recovery system and a crude distillation unit. The results of large-scale case 3 show that the optimal solution near the global optimal solution only requires 251.7 s. Case 4 includes pre-splitting in scenario A and free splitting in scenario B. Compared to scenario A, the TAC and solution time in scenario B were reduced by 33.9 % and 93.1 %, indicating that the pre-splitting strategy excludes the optimal from the search space. The proposed novel optimization framework demonstrates the efficiency and applicability of handling large-scale HEN synthesis problems. It can also guide engineers in the design of a large-scale HEN with lower costs and effort.

Failure analysis and preventative measures on cracking of tube-to-tubesheet joints of the large-scale heat exchanger

A large-scale heat exchanger in an EO/EG plant suffered a severe leakage failure after 3 years of service, and numerous fractures and cracks were found in the tube-to-tubesheet joints. A series of failure investigations, including macroscopic and microscopic inspection, physicochemical analysis, metallographic examination, and stress analysis, have been used to clarify the causes of cracking of tube-to-tubesheet joints. The macroscopic inspection revealed that the cracking of the joints occurred on the tube inlet side, and the fracture exhibited circumferential cracking. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) presented that the fracture is a mixture of transgranular and intergranular cracking (predominantly intergranular), and the surface of the fracture is covered by corrosion products with chlorine, oxygen, and copper content. Furthermore, the stress analysis concluded that the joints were subjected to residual stresses, tensile stresses, and thermal stresses. Therefore, the cracking of the tube-to-tubesheet joints was caused by stress corrosion cracking (SCC), which originated from crevice corrosion and intergranular corrosion. Then, the corrosion mechanism involved in this failure was discussed in detail, and corresponding preventive measures were proposed. Achievements in this paper may supplement the failure database of tube-to-tubesheet joints in large-scale heat exchangers and reduce similar failures through engineering practices.

A penalty-free hybrid algorithm framework based on feasible stream matching principle for large-scale heat exchanger networks synthesis

In this work, a penalty-free hybrid stochastic-deterministic algorithm framework is proposed for large-scale heat exchanger networks (HENs) synthesis (HENS), formulated as a computationally-hard mixed-integer nonlinear programming (MINLP) problem. In the outer level, an improved genetic algorithm (GA) is developed to optimize process stream matches represented by integer variables whose values are generated by a unique heat exchanger vector. Unlike previous researches, the improved GA does not rely on any penalty terms, because we propose a feasible stream matching principle to exclude all infeasible process stream matches and only feasible matches are considered in optimization process. In the inner level, a reduced-size MINLP model is solved using deterministic methods to minimize total annualized costs (TACs), which are then used to evaluate the fitness of candidate HENs. Through this way, the proposed framework combines deterministic and stochastic methods to enhance optimization efficiency and global search capability. Illustrative tests on six benchmark cases demonstrate that the framework can efficiently achieve lower-cost solutions compared to deterministic, stochastic, or hybrid methods. The results show a decrease in TAC for all six cases and a reduction in solution time ranging from 11.1% to 97.2%. Importantly, the proposed framework can be extended to solve MINLP problems in other process networks.

Lightweight Reseach of Tube Sheet for Spiral Wound Heat Exchanger Based on ANSYS

Abstract Tube sheet is the key pressure-bearing part in the spiral wound heat exchanger, and the high-strength and light-weight tube sheet structure is of great engineering significance for the development of a large-scale heat exchanger. In order to further realize the lightweight of the spiral-wound heat exchanger, this paper analyzes the influence of the thickness of the heat exchanger tube sheet on its strength based on the Ansys software and proposes the optimization design method of the tube sheet based on the strength safety factor F, which solves the problem that the software cannot take the stress linearization result as the state variable in the optimization calculation. The optimization results show that the thickness of the tube sheet is reduced by 40%. At this time, the stress strength at the connection between the tube sheet and the head and the center of the tube sheet first exceeds the design bearing capacity, indicating that the strength conditions of the two places are the controlling factors of the thickness. The results are important for the lightweight design of heat exchanger tube plate and material saving.

Environmental compatibility and economic feasibility of ground source heat pumps in tropical Asia regarding lifecycle aspects: A case study in Bangkok, Thailand

Ground source heat pumps (GSHPs) in tropical regions require a large-scale ground heat exchanger (GHE) owing to the excessive cooling load and high subsurface temperatures, resulting in increased initial costs and greenhouse gas (GHG) emissions in all phases, excluding the operation phase. However, investigations of the compatibility of GSHPs in tropical regions have been limited to evaluations based on energy consumption in the operation phase, leading to a lack of clarity regarding the contribution of increased initial cost and GHG emissions to the environmental compatibility and economic feasibility based on lifecycle aspects. Thus, this study aimed to evaluate the GHG emissions over the entire life cycle and the cost payback time of a 20-kW capacity GSHP in Bangkok, Thailand, designed with a predicted 50-year heat sink temperature. The results confirmed that the required scale of GHEs is twice as large in tropical regions as in mid‒high latitude regions; nevertheless, the energy-saving of the GSHP resulted in an 8.8 % reduction in GHG emissions over the entire life cycle compared to an air source heat pump. However, the capital investment cannot be recovered within the lifetime of the GSHP, requiring incentives and cost reduction due to the growth of the GSHP market.

Operational strategies to alleviate thermal impacts of the large-scale borehole heat exchanger array in Beijing Daxing Airport

Large-scale ground source heat pump (GSHP) systems are increasingly used for space heating and cooling. In comparison with smaller ones, large GSHP systems are often coupled with much more borehole heat exchangers (BHEs). Because of the intense thermal interactions between BHEs, they are more susceptible to significant ground temperature changes. Meanwhile, they possess the advantage that their operational strategies can be applied with a high degree of freedom, which presents chances to alleviate intense thermal interactions. In this study, we used a new performance indicator to access the effectiveness of GSHP operational strategies on alleviating thermal anomalies. The Daxing Airport GSHP system, contains 10,497 BHEs and is the largest in the world; therefore, it was selected as the test case for performance enhancement through operational strategies. We established a 2D model to predict ground temperature changes during the 50-year operation of the BHEs. First, it was revealed that the most severe thermal anomalies in the study area mainly occurred both within and between the BHE arrays, which should be mitigated. To alleviate the thermal anomalies caused by the thermal interactions of BHEs, operational strategies were applied by adjusting the cooling/heating starting sequence, setting time-dependent thermal loads, and reallocating thermal loads according to the position of the BHEs. Our study demonstrates that only the operation strategy that adjusts the cooling/heating starting sequence is beneficial for different BHE layouts, while the operational strategy that reallocates the thermal loads depending on BHEs position may be only effective for specific BHE layouts. In addition, our new performance indicator can be used to evaluate the effectiveness of the operational strategies and determine the spacing of adjacent BHE arrays. Therefore, it benefits the operation management of BHE array and design of BHE layout, and further guarantees the sustainable operation of the GSHP system.

Study on the deposition migration and heat transfer characteristics in the reactor core based on OpenFOAM

Corrosion deposition in heat exchangers may lead to a reduction in heat transfer efficiency, and even can affect equipment operational safety. Traditional CFD deposition heat transfer analysis methods are limited by model size, making it difficult to obtain global, long-term deposition heat transfer characteristics for complex heat exchange equipment. In this paper, a corrosion product deposition prediction and heat transfer model based on sub-channel analysis is proposed. By integrating it into the nuclear reactor core thermal–hydraulic characteristics analysis code CorTAF, which is developed on the OpenFOAM platform, the corrosion deposition and heat transfer calculation for the entire reactor is achieved. A numerical simulation of the deposition and heat transfer of the AP1000 reactor core during a 300-day operation is conducted. The calculation results clearly show the distribution of corrosion products in the reactor core and the temperature changes of the fuel cladding with the deposition days: the maximum deposition thickness on the core cladding surface is 38.3 μm, and the highest temperature increase is 11.0 K. The deposition and cladding temperature rise distribution is not linear with operation time but is closely related to the core power distribution. The modeling method successfully obtains the corrosion deposition and heat transfer characteristics of the entire reactor core, and has potential implications for the prediction of corrosion deposition distribution and thermal effect calculations in other large-scale heat exchange equipment.

Thermal degradation study of cotton waste pulp-based cellulose nanocrystals

Researchers are interested in cellulose nanoparticles because they are eco-friendly biomaterials with a wide range of industrial and residential applications. The purpose of this investigation is to identify the thermal degradation parameters of the isolated crystalline cellulose nanoparticles from high-quality cotton pulp in order to identify their potential as heat transfer media in large-scale heat exchange applications. A thermal parametric investigation of the nano particle sample was carried out using a variety of methods, including X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), Thermo gravimetric analysis (TGA), and Differential Scanning Calorimetry (DSC). The isolated nanoparticles have the shape of cellulose nanocrystals (CNC). An FCC lattice structure with a maximum crystallinity index of about 52% was discovered by XRD investigation. The maximum temperature of thermal deterioration was indicated by TGA data to be around 361 °C. The nano particle sample's thermal degradation temperatures and specific heat values were detailed by DSC analysis.

Modelling and prediction on the modal and harmonic response of helix tube in large-scale spiral-wound heat exchangers

Spiral-wound heat exchangers (SWHEs) have been widely used in chemical production processes. As the equipment becomes larger, the SWHEs start facing the problem of failure caused by the flow-induced vibration (FIV) phenomenon. To assure the safety and reliability of the SWHEs, it is important to understand clearly the natural modes of spirally wound coils in different sizes and their response under external excitation. Therefore, a 3D model of the helix tube is established and the helix tubes are fully investigated. The effects of different geometrical parameters on the frequency and vibration amplitude of the helix tubes are performed at each mode, by using the finite element (FE) method. Then, the vibration amplitude analysis of the helix tube under harmonic excitation is carried out, and the dangerous frequency band of the equipment under different geometrical parameters is obtained, which is mainly around 10 Hz to 40 Hz in current domain. Moreover, sensitivity analysis is presented to have a more in-depth investigation into the effects of vibration deformation and frequency, which shows that the biggest influence factor is the helix angle. Finally, machine learning is used to predict dangerous frequency, then case studies are presented to verify the validity of the regression method in which the random forest (RF) model and extreme gradient boosting (XGBoost) have the smallest error, less than 10%. The results are very important for designing SWHEs on large scale to meet the requirement of industry development.

Numerical Investigation of the Long-Term Load Shifting Behaviors within the Borehole Heat Exchanger Array System

In the process of development and utilization of a large-scale borehole heat exchanger (BHE) array system, the phenomenon of load shifting within BHE array can be observed. In this paper, OpenGeoSys software coupled with TESPy toolkit is used to establish a comprehensive numerical model of BHE system (without depicting the heat pump part), and the behaviors of load shifting between BHEs with different design parameters are studied. The results show that the outlet temperature of single BHE and BHE array is generally rising, and the soil temperature around the BHE has accumulated unbalanced heat. The soil temperature near the BHEs array fluctuates more obviously than the single BHE system, and the distribution is uneven. At the end of the 15th year, the soil temperature near the center BHE increased by 2 °C compared with the initial soil temperature, which was more favorable in winter, but was not conducive to the performance improvement in summer. Further analysis by changing the inter-borehole spacing shows that with the increase of the inter-borehole spacing, the load shifting behaviors are gradually weakened, and the maximum shifted load of the central BHE is linear with the change of the inter-borehole spacing. After changing the layout methods, we observe that the more intensive the layout is, the more load shifting behavior is, and the unbalanced rate of soil temperature distribution around the linear layout is lower than other layouts. With the increase in the number of BHEs, the load shifting behaviors are further enhanced. By analyzing the proportion of shifted load amount relative to the average value, it is found that the system will take a longer time to reach heat balance with the increase of BHEs’ number. A shutdown of part of BHEs for a certain period of time will help to improve the long-term operational efficiency of the large-scale shallow ground source heat pump (GSHP) system.

EFFECTS OF NANOPARTICLE SIZE ON PROPERTIES OF NANOFLUID AND HEAT TRANSFER ENHANCEMENT IN SPIRAL EXCHANGER USING TURBULATORS

In energy systems that use nanofluids as heat transfer fluid, the physical properties of nanofluids are important parameters in the efficiency of various heat exchangers, including small-scale micro channels or large-scale heat exchangers. In the present work, a comprehensive study is conducted to evaluate the thermal performance of a spiral heat exchanger with ball-type turbulators using nanofluid Al<sub>2</sub>O<sub>3</sub>/water. To investigate the effect of particle dimensions on nanofluid properties, nanoparticles with sizes of 20 nm and 50 nm at a volume concentration of 2% were examined. Heat transfer rate in the heat exchanger, performance evaluation criteria, heat transfer coefficient value, pressure drop, friction factor, Reynolds-Nusselt numbers relationship and pump power for fluid circulation have been calculated. ANSYS Fluent software as a computational fluid dynamic method was utilized to analyze the spiral heat exchanger under different working conditions. It was observed that both thermal conductivity and viscosity values increased as the nanoparticle size decreased. Heat transfer coefficient analyses showed that nanofluids with 20 and 50 nm particles exhibited a maximum improvement of 30.59% and 21.53%, respectively, when compared to pure water at an inlet velocity of 0.1 m/s. Additionally, the heat exchanger with turbulator showed a maximum increase of 24.87% at an inlet velocity of 0.5 m/s compared to the heat exchanger without turbulator. Moreover, maximum heat transfer rate enhancement was found to be 14.07% when the exchanger was equipped with turbulators.

Study on the random walk classification algorithm of polyant colony

Abstract With the sustained and healthy development of economy, saving energy and reducing consumption and improving energy utilization rate is a major task that enterprises need to solve. With the complex and large-scale chemical process, the heat exchange network has become complex and diverse. For more and more complex and large-scale industrial heat exchange networks, there are many different kinds of heat exchangers, the flow is complex, so the heat exchange network presents a high degree of complexity, a node status change; its disturbance transfer will influence the stability of other nodes associated with it, because of the system coupling, thus affecting the controllability and reliability of the whole heat exchanger network. Process optimization design of heat exchange network is one of the main methods of energy saving in the industrial field. As a typical simulated evolutionary algorithm in swarm intelligence algorithm, ant colony algorithm combined with random walk classification algorithm, this article proposes an optimized heat transfer network based on multi-ant colony random walk classification algorithm. The heat exchanger was abstracted as a node, and the heat exchanger pipeline was abstracted as a side. According to the maximum geometric multiplicity of the eigenvalue of the adjacency matrix and the linear correlation row vector of the matrix, and combining the importance of the edge of the heat exchange network with the controllable range of the driving edge, the optimal control driving edge of the heat exchange network is identified. The results show that compared with the traditional heat exchanger, the size of the enhanced heat transfer equipment and the influence of pressure drop change. Compared with the results of the size of the heat exchanger strengthening heat transfer equipment and the stepwise optimization of the heat exchange network in this study, the cost of public engineering is reduced by 5.98% and the total cost is reduced by 8.83%.

Al–Ni alloy-based core-shell type microencapsulated phase change material for high temperature thermal energy utilization

Latent heat thermal energy storage (LHTES) using alloy-based phase-change materials (PCMs) is a promising technique for stabilizing the power supply of grid-connected renewable energies. In particular, recently developed alloy-based microencapsulated PCMs (MEPCMs) are attracting considerable attention owing to their ease of handling and ability to overcome the problems of corrosion and melting leakage experienced by alloy PCMs. To expand high-temperature LHTES, more MEPCMs need to be developed. In this study, an MEPCM was developed using Al-5 wt.%Ni alloy (melting point 640°C). Microencapsulation was performed in two steps: 1) Al hydroxide layer formation on the surface of PCM particles by boehmite treatment in boiling water for 1 h or 3 h and 2) Al 2 O 3 shell formation by heat oxidation treatment in an O 2 atmosphere. The prepared MEPCM consisted of an α-Al 2 O 3 shell and an Al–Ni alloy core. The sample after 1 h of boehmite treatment and heat oxidation treatment had melting and solidification latent heat capacities of 241 J g –1 and 251 J g –1 , respectively. The developed MEPCM maintained its original shape and high latent heat capacity, even after 100 cycles of melting and solidification. The developed Al–Ni alloy-based MEPCM is expected to be applied to next-generation LHTES, in which a large-scale and ultrafast heat exchange system is employed in a small space by cascade configuration with other MEPCMs with different melting points. In addition, the formation of the Al–Ni alloy core/α-Al 2 O 3 shell structure was investigated thermodynamically, providing insights that will promote the development of Al- X alloy-based MEPCMs in the future. • Al–Ni alloy based microencapsulated phase change materials (MEPCMs) were developed. • The prepared MEPCM consisted of an α-Al 2 O 3 shell and an Al–Ni alloy core. • The MEPCM exhibited high thermal storage capacity about 241 - 251 J g -1 . • The MEPCM had melting temperature of 640°C. • They are good candidates for high-temperature thermal energy storage application.

A global model for fast calculation of the thermal response factor of large-scale boreholes heat exchangers combining the FLS model, the 2D heat equation and a three-points method

In order to progress towards more energy efficient buildings, vertical ground coupled heat pumps are a promising solution. Optimisation of both the design and operation of boreholes heat exchangers is a key factor to reduce energy consumption of such systems. This requires a fast evaluation of the thermal response factor of the ground heat exchanger, particularly if it contains numerous boreholes and operates for multiple years. To overcome this challenge, this article reports a new global model combining the finite line source (FLS) model, the two-dimensional (2D) heat conduction equation, and a newly developed three-points method. The borehole field is sorted in increasing distance categories, each being simulated with varying timesteps. The 2D heat conduction equation is used to determine: 1) when the detailed calculation needs to be performed; and 2) the growth of the timestep. A three-points method avoiding double integration of the temperature profiles is proposed to evaluate the borehole wall temperature. The global model calculation time and accuracy were evaluated. The thermal response factor calculation for a square field of 26×26 boreholes for one simulated year took 4s, showing a calculation time reduction factor of around 1,000,000, and relative errors smaller than 2 % compared to the original FLS model with superposition principle. For 20 simulated years, the proposed model took only 1min. It is appropriate for various boreholes configurations. Its features such as accuracy, speed and load-independency are essential for its integration into building energy simulation tools.

Experimental and Numerical Analysis of a Plate Heat Exchanger Using Variable Heat Transfer Coefficient

Thermal design and analysis of heat exchangers are predominantly conducted considering constant heat transfer coefficients. However, these vary along the length and affect the calculations of heat transfer rates and area allocations. The current paper investigates the variations in the heat transfer coefficients in plate heat exchangers (PHX), using different numerical approaches. The heat transfer coefficient is calculated at the inlet, outlet, and systematically selected intermediate points for each method. The analysis is conducted for two different systems, i.e., a laboratory-scale and an industrial scale PHX at different chevron angles. It is concluded that the effect of the variable heat transfer coefficient is more significant for the large-scale heat exchanger due to high flow rates, geometrical specifications, Reynolds number, and thermophysical properties. The deviation of the local heat transfer coefficient along the heat exchanger length is approximately 9–14% and 3–6% for industrial and laboratory scale PHX, while an area deviation of around 15% is observed.

Investigation of Heat Transfer in a Large-Scale External Heat Exchanger with Horizontal Smooth Tube Bundle

In the research work, energy transport between a dense fluidized bed and submerged horizontal tube bundle is analyzed in the commercial external heat exchanger (EHE). In order to investigate the heat transfer behavior, the authors carried out eight performance tests in a fluidized bed heat exchange chamber with a cross-section of 2.7 × 2.3 m in depth and width and a height of 1.3 m. The authors have been developing a mechanistic model for the prediction of the average heat transfer coefficient, which includes the effect of the geometric structure of the tube bundle and the location of the heat transfer surface on the heat transfer rate. The computational results depict that the average heat transfer coefficient is essentially affected by superficial gas velocity and suspension density rather than bed particle size. The empirical correlations have been proposed for predicting heat transfer data since the existing literature data is not sufficient for industrial fluidized bed heat exchangers. On the basis of the evaluated operating conditions of an external heat exchanger, the optimal conditions where heat transfer occurs could be deduced. The developed mechanistic heat transfer model is validated by experimental data under the examined conditions.

Node dynamic adaptive non-structural model for efficient synthesis of heat exchanger networks

Balancing the trade-off between structural diversity (solution space) and optimization efficiency is an urgent challenge in the modeling and global optimization of heat exchanger network synthesis problems. This paper presents a node dynamic adaptive non-structural model without stream splitting to enhance optimization efficiency under the premise of ensuring an adequate solution space. The node-based non-structural stream matching mechanism can be used to make the solution space scalable and achieve the efficacy of multi-stage stage-wise superstructure with a finite number of nodes. Two node dynamic adaptive strategies (uniformly distributed and random) are established to periodically adjust the number of nodes in process streams and the node distribution of existing heat exchanger units, thereby preventing a decrease in computational efficiency due to an excess number of preset nodes while still satisfying the solution space requirements. The node dynamic adaptive non-structural model is optimized using the random walk algorithm with compulsive evolution. The proposed method was applied to four well-known heat exchanger network case studies. High-quality solutions were obtained, and they are more economical than most of the optimal results previously reported in the literature. These results demonstrate the enhanced computational efficiency and applicability of the proposed synthesis method based on a node dynamic adaptive non-structural model for efficiently solving large-scale heat exchanger network synthesis problems.

A successive flux estimation method for rapid g-function construction of small to large-scale ground heat exchanger

This paper presents a modification of the successive flux estimation algorithm of Pasquier and Marcotte (2013) [1] for computation of the so-called g-functions of small to large-scale ground heat exchanger fields. Fast calculation times are obtained by spectral convolution of the incremental flux signal and the borehole transfer function in an iterative scheme. An initial guess that is close to the solution and easily computable is also suggested for fast convergence. Further gains are obtained through the preprocessing of the transfer functions and the sub-sampling of the g-function. The proposed method was compared against the original successive flux estimation method, as well as two other rapid methods in the literature. Results show that the algorithm proposed in this work is by far the fastest and can generate a 40 year g-function of a large ground heat exchanger field composed of 400 randomly positioned boreholes in less than 4 s. The proposed approach is general and can manage fields composed of different number of boreholes and configurations.

A novel two-step synthesis method with weakening strategy for solving large-scale heat exchanger networks

Efficiently solving large-scale heat exchanger network (HEN) synthesis problems remains a challenging task mainly due to the presence of discontinuity caused by integer variables as well as nonlinearity of the objective cost function. This paper focuses on efficiently solving large-scale HEN synthesis problems based on a chessboard presentation with no splits, and aims to achieve globally near-optimal solutions by using a two-step synthesis method along with a weakening strategy for fixed investment costs that is conducive to bypass the discontinuity. The first step is to generate the most promising network structure by using an improved cuckoo search algorithm to optimize integer and continuous variables simultaneously. In the second step, a cuckoo search algorithm is utilized to directly optimize the heat exchanger area of the optimal structure obtained in the first step. Meanwhile, fixed-cost weakening strategies are applied in the above two steps for improving the optimization efficiency. The proposed method has been tested on several HEN cases, and two of which, namely the 20- and 39-stream problems, are presented in this paper. For these two cases, although the solutions obtained do not contain stream splits, their total annual costs are close to best solutions with stream splits and lower than those best solutions with no-splits reported in the literature, and their chessboard network configurations are clear and simple. Based on these results, the developed method demonstrates the applicability to handle large-scale HEN problems, and is also useful for guiding the grassroots or retrofit design of large-scale HENs or other engineering process syntheses with less cost and less pollution.