Petar Sabev Varbanov
6603469420
Publications - 35
Dynamic modelling of vapour compression cycles based on an all-mode switchable moving boundary model
Publication Name: Applied Thermal Engineering
Publication Date: 2025-11-15
Volume: 279
Issue: Unknown
Page Range: Unknown
Description:
With the increasing demand for energy and growing environmental concerns, research on the performance and dynamic control strategies of chillers is vital for energy conservation and emission reduction. This work presents a seventh-order nonlinear moving boundary model with an all-mode switchable scheme for evaporators and condensers of vapour compression cycles. The proposed model, encompassing six modes, introduces a robust switching scheme that supports adjacent-mode and cross-mode transitions. Key advancements include a refined void fraction derivative model, addressing prior simplifications, and heat transfer coefficient modelling for louvred tube-fin and microchannel heat exchangers, extending applicability beyond round-tube designs. A dynamic simulation of a chiller system, validated against integral calculations, demonstrated high accuracy with simulation errors below 0.9 % and mass and energy variations of 0.15 % and 0.27 % over 24 h. A refrigerant charge model identified 0.02995 kg as optimal for maximising COP and cooling capacity under varying conditions. Steady-state and dynamic analyses showed that increased compressor speed enhances cooling performance by boosting flow rates and temperature differentials, while air velocity improves condenser efficiency and system COP. The dynamic response exhibited rapid pressure fluctuations with slower temperature changes due to external variations or heat exchanger efficiency. These findings underline the model's reliability and practical relevance.
Open Access: Yes
Equation-oriented thermodynamic optimisation of heat pump integration in industrial heat recovery systems: A system-level pathway to cost and emission reduction
Publication Name: Energy
Publication Date: 2025-10-30
Volume: 335
Issue: Unknown
Page Range: Unknown
Description:
Integrating heat pumps into large-scale electricity-to-heat industrial processes has proven highly successful in enhancing the utilisation of renewable energy and contributing to carbon emission reductions. However, most studies focus on overall system performance, overlooking the detailed thermal behaviour of the heat pump itself. This limits the adaptability of heat pumps in dynamic industrial settings. This work proposes an equation-oriented framework that enables flexible integration of thermodynamically detailed heat pump models into industrial heat recovery systems. A superstructure-based optimisation model is developed to minimise energy costs and enhance efficiency, considering process constraints, network layout, and heat pump performance. The model dynamically optimises heat pump operation and placement to enhance waste heat recovery and overall system integration. Moreover, the approach supports the integration of low-grade utilities to further improve the energy efficiency. The proposed framework is validated through an industrial-scale case study of a crude oil distillation process. Life cycle assessment is conducted to quantify potential environmental and economic benefits. Results show that integrating heat pumps into the system recovered 50.52 % of low-pressure steam, reducing the total operating cost and annual cost by 12.88 % and 12.42 %. Additionally, total net carbon emissions decreased by 28.70 %. Lower electricity prices increase heat pump use and economic benefits but also amplify rebound effects. Furthermore, although high-temperature heat pumps operating above 150 °C tend to increase capital expenditures, they unlock greater energy efficiency, thereby accelerating the industrial decarbonisation process.
Open Access: Yes
Integrated multi objective mixed integer nonlinear programming approach for emission and energy minimization in industrial boiler-turbine networks
Publication Name: Energy
Publication Date: 2025-10-30
Volume: 335
Issue: Unknown
Page Range: Unknown
Description:
This study investigates the optimization of a co-generation system involving multiple steam boilers and turbines, aiming to minimize CO2 emissions and energy consumption while maintaining reliable energy delivery. A hybrid Genetic Algorithm (GA) and Sequential Quadratic Programming (SQP) method is implemented within a Multi-Objective Mixed-Integer Nonlinear Programming (MOO-MINLP) framework. The approach effectively captures the nonlinear behavior of efficiency and operational constraints. The results show a reduction of up to 10 % in CO2 emissions and over 35 % in energy savings compared to GA-only approaches. Maximizing biomass usage at Extreme Point A achieves the lowest emissions (554.29 kg) and an energy cost of 4253.69 GJ, while minimizing energy consumption at Extreme Point C leads to 3532.67 GJ but higher emissions (708.86 tons). This study demonstrates the hybrid GA-SQP method's potential to optimize both CO2 emissions and energy consumption, offering decision-makers a balanced approach between cost and environmental impact. The results underscore the significance of fuel allocation, especially biomass, in reducing emissions despite lower efficiency, presenting a cost-effective and sustainable solution for co-generation system optimization.
Open Access: Yes
Dynamic regulation strategy of the SCO2 Brayton cycle system based on PCM and its instability evaluation model
Publication Name: Energy
Publication Date: 2025-10-15
Volume: 334
Issue: Unknown
Page Range: Unknown
Description:
The dynamic study of the Supercritical Carbon Dioxide (SCO2 ) Brayton cycle has received extensive attention from the industry in recent years. While various dynamic operating conditions occur intermittently within the system, some commonly used control methods are unable to adapt effectively to those situations. In this study, a dynamic model of the SCO2 Brayton cycle coupled with a printed circuit heat exchanger with embedded PCM, a storage tank, and a proportional-integral-derivative (PID) controller was developed and validated with the model, and then the control effects of the various control models were compared in terms of their control effectiveness under three typical variable operating conditions (periodic temperature fluctuation, load reduction and recovery, and reduced flow rate). In addition, the stability assessment of the SCO2 Brayton cycle was modeled. Compared to the basic SCO2 Brayton cycle, the PCM-PCHE reduces the amplitude of the total efficiency fluctuations by 44.8 %, and the integrated layout covering the printed circuit heat exchanger with embedded PCM, storage tank, and PID controller shows the best stability. Controlling the extraction ratio with a PID controller contributes more to the stability of the SCO2 Brayton cycle than controlling the condensate flow rate with a PID controller. In contrast, the printed circuit heat exchanger with an embedded PCM contributes more to the stability of the SCO2 Brayton cycle concerning the storage tank. Overall, the total control layout reduced the instability by about 40 % compared to the initial recompression layout, indicating that the PCM, storage tank, and PID controller greatly improved the stability of the SCO2 Brayton cycle.
Open Access: Yes
Short-period supply reliability evaluation of a gas pipeline network based on transient operation optimization and support vector regression
Publication Name: Energy
Publication Date: 2025-09-15
Volume: 331
Issue: Unknown
Page Range: Unknown
Description:
The gas pipeline network is a critical infrastructure connecting downstream customers and upstream sources, and the gas supply condition of the gas network directly impacts people's lives. In this paper, a novel methodology is proposed to evaluate the short-period supply reliability of a gas pipeline system based on transient operation optimization and support vector regression. Firstly, supply and demand uncertainty characteristics are analyzed, and representative scenarios are selected through the improved Latin Hypercube Sampling method. Secondly, the transient peak-shaving characteristics are studied, and the physical transient peak-shaving operation optimization model is established to evaluate the satisfaction rate of gas customers and the system under representative scenarios. Then the Support Vector Regression model based on the improved Particle Swarm Optimization is established to predict the satisfaction rate of the customer or system under each random scenario, and the probabilities under different satisfaction degrees of the customer and system are given to reflect the supply reliability of a gas network. The proposed integrated methodology is verified by a specific gas pipeline system, and the results show that the maximum and the mean absolute error of the predicted satisfaction rate of the system's demand quantity can be reduced to 0.0070 and 0.0009, and the time consumed for the evaluation process can be reduced by 95 % compared to the traditional pure physical model. The proposed methodology can lay a solid foundation for the grasp of the short-period supply reliability of gas networks.
Open Access: Yes
Future of Agrivoltaic projects: A review from the technological forecasting perspective
Publication Name: Cleaner Engineering and Technology
Publication Date: 2025-09-01
Volume: 28
Issue: Unknown
Page Range: Unknown
Description:
Agrivoltaic systems integrate photovoltaic (PV) energy generation with agricultural production, creating synergies that enhance land-use efficiency and environmental sustainability. This article reviews agrivoltaic technologies to identify key trends and the most promising future research and development directions. The method applied involves selecting and analysing relevant literature sources and filtering them with regard to the essential questions that need to be answered for the climates of Central Europe and China. These include global development, current applications, and technological progress. The analysis reveals growing attention to system design, performance optimisation, and crop compatibility. Innovations such as bifacial and spectrally selective PV modules boost energy yields while maintaining suitable conditions for shade-tolerant crops like leafy greens and berries. The analysis confirmed the high potential of sustainability benefits (societal, economic, and environmental) and revealed the need for systematic investigations of significant performance factors, including location and system design. A relatively underinvestigated factor is the protection of crops from excessive sunlight, which has become increasingly important. The modelling and optimisation of system operation is also necessary to provide decision-makers with robust tools for project assessment. A roadmap is proposed to guide future research and development.
Open Access: Yes
Heat transfer intensification in compact heat exchangers with channels of various geometries and size
Publication Name: International Communications in Heat and Mass Transfer
Publication Date: 2025-09-01
Volume: 167
Issue: Unknown
Page Range: Unknown
Description:
The need to decrease the sizes and masses of heat exchangers while preserving their performance has stipulated the development in compact heat exchangers (CHEs). It is supported by the additional push from process industries for increased recuperation of heat energy, facilitating better energy efficiency in process plants with strict limitations for space, material and cost. The adequate substitution of conventional heat exchangers by CHE in the same process conditions requires maintaining the same heat load not exceeding the allowable pressure losses. The different ways to increase the compactness of CHE are analysed, including the change of hydraulic diameter of heat exchanger channels, and the use of various methods of heat transfer intensification by changing channel geometry and flow structure. The Nusselt numbers and friction factors correlations for plane tubes, enhanced tubes and channels of plate heat exchangers are compared based on available literature data. A newer form of the core velocity equation is developed, which allows a comparison of the performance of CHE heating surfaces with different enhancement techniques and varying scales in specific process conditions. The results of the calculations illustrate the influence of the channel's hydraulic diameter and length on CHE thermal and hydraulic performance for channels with heat transfer intensification. The recommendations on choosing the best channel geometry and size, depending on specified process conditions and stream nature, are formulated.
Open Access: Yes
Investigation of the synthesis and thermal insulation properties of K2Ti6O13 whisker-reinforced SiO2 micro powder composite coating fabrics
Publication Name: Energy
Publication Date: 2025-08-01
Volume: 328
Issue: Unknown
Page Range: Unknown
Description:
Developing functional textiles with thermal insulation and hydrophobic properties is of significant interest. This study successfully synthesizes K2 Ti6 O13 (potassium titanate, KTO) whiskers via the hydrothermal method and prepares KTO composite silica polyester fabric (KSP) through impregnation technology, exhibiting excellent thermal insulation and hydrophobic qualities. X-ray diffraction (XRD) analysis verifies the high purity and excellent crystallinity of KTO whiskers and SiO2 micro-powder. Scanning electron microscopy (SEM) images reveal that the KTO whiskers retain their original morphology and exhibit uniform size distribution, with an average length of around 1 μm and an aspect ratio of 40. Transmission electron microscopy (TEM) images further validate the planar growth properties of the whiskers. Raman spectroscopy research elucidates the vibrational modes of various chemical bonds in the KTO whiskers. The ultraviolet–visible–near-infrared spectrophotometer test results demonstrate that the KSP fabric reflects 43.5 % more light than standard polyester fabric and substantially lowers the temperature in the covered chamber under simulated sunlight exposure, achieving a maximum reduction of 7.4 °C. The KSP fabric has exceptional hydrophobic properties, completing a contact angle of 153.2° and maintaining reflectance stability, with a mere 5.92 % reduction after 20 days of outside exposure. This work offers substantial reference value for the advancement of practical textiles.
Open Access: Yes
Mechanism of environmental regulation on energy productivity, energy structure, and carbon emissions: The role of directed technological progress
Publication Name: Energy
Publication Date: 2025-08-01
Volume: 328
Issue: Unknown
Page Range: Unknown
Description:
The mechanism of environmental regulation on energy conservation and carbon reduction in the petrochemical industry through directed technological progress remains uncertain due to the directional characteristics of technology. This paper develops a mechanism framework and employs a panel two-way fixed-effects model to clarify the impact of environmental regulation on directed technological progress and energy conservation, while uncovering its underlying mechanisms. Subsequently, a dynamic Kaya model is constructed, using the Monte Carlo method to determine the required intensity of environmental regulation for China's petrochemical industry to actualize the SSP1-CHN, SSP1, and SSP2 scenarios. The model also simulates the future bias of technological progress, energy utilization, and potential carbon emissions under each scenario. The findings indicate that increasing the intensity of environmental regulation drives technological progress toward energy conservation, thereby enhancing energy-saving biased technological progress, improving energy productivity, and optimizing the energy structure. Furthermore, to actualize the carbon peak by 2030 and carbon neutrality by 2060 under the SSP1-CHN scenario, the annual growth rate of environmental regulation intensity in China's petrochemical industry should be no less than 8 % before 2030 and should be strengthened to 20 % after 2030.This study not only extends the application of directed technological progress theory in the energy field but also provides innovative and practical environmental policy recommendations for the low-carbon development of the global petrochemical industry.
Open Access: Yes
Optimisation of island integrated energy system based on marine renewable energy
Publication Name: Fundamental Research
Publication Date: 2025-09-01
Volume: 5
Issue: 5
Page Range: 2161-2179
Description:
Integrating marine renewable energy (MRE) with conventional energy sources and logically constructing island energy systems is crucial for alleviating island energy supply challenges and helping coastal energy systems achieve a sustainable, low-carbon transition. In this study, the status of marine energy utilisation technologies is reviewed, with a focus on advancements in energy conversion equipment, grid integration, and energy storage. The economic feasibility and environmental sustainability of marine energy systems are comparatively analysed to enhance the development and utilisation of marine energy technology while reducing the economic cost of power generation. Suitable equipment is highlighted for islands, with efficient energy generation strategies proposed to achieve cleaner, localised, and cost-effective island integrated energy system (IIES) design. Island energy facilities vary, and integrated development is crucial for building new energy systems. Based on the types and resources of island energy, IIESs are constructed for hierarchical energy utilisation and multi-energy coupling, coordinating resources to achieve source–grid–load–storage integration. The optimisation of IIESs is reviewed, with a focus on modelling methods, intelligent algorithm development, and system simulation. This study differs from previous research as it considers the integration of marine energy into existing systems to achieve comprehensive integration of multiple energy sources. Additionally, optimisation and solution methods for IIES models are summarised. To integrate complex, multivariable energy systems and create stable and predictable outputs, marine energy and load forecasting methods are explored. Overall, this study supports the advancement of marine energy utilisation, focusing on its progressive integration into island energy systems as the efficiency of marine energy improves. This work aims to inspire the development of new functions and modules based on existing system optimisation and forecasting techniques.
Open Access: Yes
Assessing the effectiveness of RS, GIS, and AI data integration in analysing agriculture performance to enable sustainable land management
Publication Name: Discover Sustainability
Publication Date: 2024-12-01
Volume: 5
Issue: 1
Page Range: Unknown
Description:
The integration of Earth Remote Sensing (ERS) data with advancements in artificial intelligence has revolutionised sustainable land management. Current research in this field focuses on analysing remotely sensed data. This paper presents the results of effectively using spectral reflectance values of soil samples from several climatic zones in Kazakhstan to classify the content of macronutrients in soil, including nitrogen, phosphorus, potassium, and humus. The analysis of macronutrient content in the soil, combined with spectral data from Sentinel-2 L2A satellite imagery, has been integrated with geoinformation systems and mathematical modelling. The results of the macronutrient classification have been visualised in the form of cartograms. The classification analysis involved mathematical modelling of statistical data arrays on the content of phosphorus, potassium, humus, and nitrogen in the soil using the BN-BPNN neural network model, compared with data obtained from agrochemical soil sampling. The model tests demonstrate high efficiency for two soil types. For chernozem soil, the accuracy of nitrogen determination was 90.55%, phosphorus 98.1%, potassium 57.06%, and humus 90.54%. For chestnut soil, the accuracy was nitrogen 98.19%, phosphorus 42.16%, potassium 89.81%, and humus 98.88%. These results highlight the significant potential of this methodology for adaptation to various soil and climatic conditions. The “smart” technique developed for remote determination of macronutrient content, with automated express construction of cartograms, provides real-time information on soil nutrient levels. This research significantly enhances the integration efficiency of RS (remote sensing), GIS (geographical information systems), and AI (artificial intelligence) data in agriculture, contributing to sustainable land management.
Open Access: Yes
Mechanism of directed technological investment on energy productivity and energy structure: A unified theoretical framework
Publication Name: Energy Economics
Publication Date: 2024-12-01
Volume: 140
Issue: Unknown
Page Range: Unknown
Description:
The mechanisms and effects of technological investment on energy productivity and energy structure in the petrochemical industry remain unclear due to the directional nature of technological progress. This study proposes a unified theoretical framework for the impact of directed technological investment on energy productivity and energy structure by incorporating energy factors into the theory of technological progress bias. The aim is to elucidate the impact of technological progress on energy productivity and energy structure, and to unravel the underlying effect mechanisms. A fixed effects model that includes moderating effects is also developed to support the assessment. The study found that the petrochemical industry's technological investment in China was initially biased towards enhancing labour-augmenting technological progress. The mechanism analysis revealed that technological investment, under the moderating effects of price and environmental governance, preferred a capital-energy bias, leading to insignificant improvements in energy productivity but a substantial increase in labour productivity. In addition, the technological investment, influenced by the moderating effect of environmental governance, led to some improvement in the energy structure during the sample period. This study integrates the mechanisms of directed technological investment on energy productivity and energy structure into a unified analytical framework, systematically investigating the reasons, effect mechanisms, and consequences of bias, while providing empirical evidence that supports low-carbon development in the petrochemical industry.
Open Access: Yes
Review of best practices for global cogeneration policy: Benchmarking and recommendations for Malaysia
Publication Name: Energy
Publication Date: 2024-11-30
Volume: 310
Issue: Unknown
Page Range: Unknown
Description:
Despite the Malaysian government's efforts to promote cogeneration technology, it constitutes a mere 4.2 % of the country's total electricity generation. To address this issue, this review article aims to identify and benchmark global best practices for bolstering cogeneration implementation in Malaysia. While previous studies in this domain have centered on examining government policies within the specific regions, this paper underscores the imperative for an updated and comprehensive literature review to systematically collect and categorise best practices from around the world. This work examines the adoption of cogeneration energy systems within nations characterised by a substantial presence in their energy composition, simultaneously exploring the roles of regulatory frameworks in promoting their uptake. The scope of the literature review includes statistical data, reports, and other relevant scholarly works on cogeneration policies. Based on the findings, the review paper concludes that well-crafted policies are instrumental in encouraging rapid technology advocacy. The legislative landscape pertaining to cogeneration implementation in Malaysia is scrutinised, followed by a comparative analysis against global best practices to identify opportunities for improvement. Three crucial elements emerge as paramount to expediting the adoption: (i) administrative recognition, (ii) financial initiatives, and (iii) regulatory improvements. Several recommendations for the Malaysian cogeneration roadmap are presented. Overall, this paper offers insights into the chronological evolution of cogeneration policy development and provides actionable guidelines for developing effective policies in Malaysia and other South-East Asian countries.
Open Access: Yes
Corrigendum to ‘Graphical pinch analysis-based method for heat exchanger networks retrofit of a residuum hydrogenation process’ [Energy volume 299 (2024) 131538] (Energy (2024) 299, (S0360544224013112), (10.1016/j.energy.2024.131538))
Publication Name: Energy
Publication Date: 2024-11-30
Volume: 310
Issue: Unknown
Page Range: Unknown
Description:
The contribution of Pawel Oclon has been funded by the EU project “Renewable energy system for residential building heating and electricity production–RESHeat”, Grant Agreement #956255. The work of Petar Varbanov has been funded by the Széchenyi István University in Hungary. The authors would like to apologise for any inconvenience caused.
Open Access: Yes
Strategic integration of residential electricity: An optimisation model for solar energy utilisation and carbon reduction
Publication Name: Energy
Publication Date: 2024-11-30
Volume: 310
Issue: Unknown
Page Range: Unknown
Description:
The Solar Combined Cooling, Heating, and Power (S-CCHP) system, distinct from traditional centralised generation, provides clean energy solutions by installing user-side renewable energy capture facilities like solar panels to address the energy crisis and mitigate global warming. Previous research on the design of S-CCHP for buildings has often emphasised self-sufficiency, with less focus on the role of these systems as energy suppliers on the market. However, it is feasible to install scaled-up solar facilities that generate enough power to export to the grid, reducing grid pressure and enhancing the renewable energy mix. This study analyses the optimal design deployment for electricity within the S-CCHP system, based on the Renewable Energy System for Residential Building Heating and Electricity Production (RESHeat) system installed in Limanowa. It aims to optimise owner energy deployment by strategically integrating electricity generation, hybrid storage, and the electricity market to maximise owner benefits. A Life Cycle Assessment is also conducted to explore greenhouse gas emissions across scenarios with different storage facilities and reuse rates. Results show that the optimal deployment of 264 PV panels, each with a rated power of 440 W, generates 105 MWh annually, resulting in the surplus of 90.18 MWh with a selling price of 115 EUR/MWh. Vanadium redox flow batteries offer the highest revenue (4922.01 EUR) with the lowest storage costs, while lithium-ion batteries have the lowest carbon emissions (1.22 t CO2 eq/y). Sensitivity analysis and revenue break-even analysis are further conducted to assess the robustness and financial viability.
Open Access: Yes
Spatiotemporal prediction of greenhouse gas emissions from rubber wood industry, taking Hainan as the case
Publication Name: Journal of Cleaner Production
Publication Date: 2024-11-15
Volume: 480
Issue: Unknown
Page Range: Unknown
Description:
The rubber wood furniture industry chain, including planting and manufacturing subsystems, emits significant greenhouse gases (GHGs), meanwhile, has huge carbon emission reduction potential. However, quite few studies have taken the whole industry chain GHGs into consideration, especially assessing and predicting those from rubber tree planting to furniture manufacturing. We took the rubber wood furniture of Hainan province as the case, explored its whole life cycle GHGs from cradle-to-gate and predicted the potential GHGs from 2031 to 2062. This study is fully based on field survey and sampling data, including that of the rubber tree planting (40-year cycle) and furniture manufacturing. The results reveal: (1) Whole industry chain of rubber wood furniture emits 3.27 × 106 kgCO2 -eq GHGs per 20,000 t rubber logs consuming, where the planting accounts the most (88.20%). Transport and electricity consumption are the main GHGs sources of planting and manufacturing subsystems respectively; (2) The whole life-cycle GHGs of rubber wood furniture in 2023 of Hainan is 2.07 × 107 kgCO2 -eq, which mainly come from Danzhou (24.74%), Haikou (19.55%), and Qiongzhong (15.79%); (3) The total GHGs from the rubber wood furniture industry in Hainan from 2031 to 2062 are 210 MtCO2 -eq and 129 MtCO2 -eq respectively, without or with felling restriction. The changes of GHGs from 2051 to 2062 are caused by the regional center shift of planting gravity; (4) Improving energy use efficiency and optimizing the location of furniture factories would reduce GHGs. This study can provide empirical support for the low carbon sustainable transformation of the rubber wood furniture industry worldwide.
Open Access: Yes
Blockchain-based concept for total site heat integration: A pinch-based smart contract energy management in industrial symbiosis
Publication Name: Energy
Publication Date: 2024-10-01
Volume: 305
Issue: Unknown
Page Range: Unknown
Description:
Industrial symbiosis has gained prominence in pursuing sustainable industrial practices, aiming to optimise resource utilisation and reduce environmental impacts. A critical aspect of this endeavour is the efficient management of energy resources within an industrial ecosystem. This paper presents a novel approach to enhance Total Site Heat Integration (TSHI) implementations by employing Blockchain as a facilitator for decentralised energy management. TSHI is an efficient and widely applied method for industrial symbiosis concerning energy flows, which employs the steam mains in site utility systems as the platform for exchanging heat between industrial processes at various temperature levels. It is shown that the synergy of Pinch Analysis and Smart Contract technologies is capable of facilitating energy integration of processes belonging to independent market actors, compared with the currently dominant integration inside a single company. The proposed framework leverages Blockchain as a distributed ledger to enable secure, transparent, and automated energy management across multiple industrial entities in an industrial symbiotic network. The integration of Pinch Analysis principles ensures that the Heat Integration process is optimised to improve the overall energy efficiency. Smart contracts enable automatic negotiation and execution of energy transactions based on predefined rules, minimising the time lag for concluding deals on energy resource exchange and conservation. This paper examines several scenarios to illustrate the implementation of the proposed Blockchain-based TSHI concept within an industrial symbiosis network. It is demonstrated that up to 16 % cost savings are possible by simply enabling transparency via Blockchain. The results could drive innovative development to revolutionise decentralised energy management in a complex industrial ecosystem, especially by synchronising energy exchanges in time.
Open Access: Yes
Operational optimisation of integrated solar combined cooling, heating, and power systems in buildings considering demand response and carbon trading
Publication Name: Energy Conversion and Management
Publication Date: 2024-09-01
Volume: 315
Issue: Unknown
Page Range: Unknown
Description:
The Solar Combined Cooling, Heat, and Power (S-CCHP) system offers a promising solution to the energy crisis and environmental concerns. Its operation optimisation is essential due to intermittent solar irradiation. However, previous studies have concentrated on the “electricity-heating” subsystem and economic costs, with less emphasis on the integrated system's broader benefits and environmental impact. This study introduces an operational optimisation approach across “electricity-heating-cooling-gas” subsystems based on the design extension of the Residential Building Heating and Electricity Production (RESHeat) system. Specifically, the approach optimises operation from both the demand and supply sides, incorporating the demand response (DR) and Ladder Carbon Trading (LCT) on the demonstration in Limanowa, Poland, to balance economic and environmental impacts. The results show that the optimised electricity is reduced by 0.71 % per day while heating and cooling demands rise by 0.57% and 0.91%. PV/T panels provide 87.11% of electricity, with excess sold back to the grid in summer. DR combined with LCT in the extension design contributed to cutting costs by 16.15 % and CO2 by 57.79% compared with the initial design, underscoring the efficacy of collaborative operational in enhancing both economic and environmental performance.
Open Access: Yes
Graphical pinch analysis-based method for heat exchanger networks retrofit of a residuum hydrogenation process
Publication Name: Energy
Publication Date: 2024-07-15
Volume: 299
Issue: Unknown
Page Range: Unknown
Description:
Sustainable energy systems are crucial for reducing carbon emissions because renewable energy sources leave a footprint. The petrochemical industry often suffers from inefficient heat exchange network (HEN) systems, leading to substantial energy wastage. In the current work, a real case study of the residue hydrogenation process was analyzed to identify potential energy savings. A new method combining Pinch Analysis and Thot –Tcold diagram analysis methods was proposed. This graphical analysis method plots the cold-flow temperature of each heat exchanger unit on the x-axis and the hot-flow temperature on the y-axis. By applying the Thot –Tcold diagram to a practical case of residue hydrogenation in Zhejiang, the existing process energy state was evaluated, and HEN was retrofitted to achieve energy savings and carbon emission reduction. Following optimization, the energy recovery amounted to 202.71 GJ/h with an energy recovery rate of 14.3 %. The proposed method saves approximately 4.058 × 105 GJ/y compared to current operations, resulting in an annual cost saving of approximately $ 2.76 M/y, with an investment payback period of less than 0.36 y. This study offers a solution to the energy challenges of industrial residue hydrogenation by enhancing the economic and environmental sustainability of existing process flows.
Open Access: Yes
Dynamic simulation of particle deposition on the blade leading edge with film cooling in gas turbines
Publication Name: Thermal Science and Engineering Progress
Publication Date: 2024-06-01
Volume: 51
Issue: Unknown
Page Range: Unknown
Description:
Particle deposition on the leading edge was investigated in gas turbines numerically. The research investigated the effects of the inclination angle and blowing ratio on the deposition thickness, and cooling effectiveness of the leading edge. Particles were released from the main inlet of the computational domain. The deposition on the leading edge was judged using the double deposition model. The results show that the deposition thickness is inversely proportional to the blowing ratio. The deposition thicknesses for 0°, 20°, 40°, and 60° inclination angles decrease by 7.82 %, 6.84 %, 7.44 %, and 5.34 %, with the increase in the blowing ratio from 0.5 to 2.0 at 30 s. The deposition thicknesses with four inclination angles decrease by 6.79 %, 7.24 %, 6.79 %, and 5.34 % by increasing the blowing ratio from 0.5 to 2.0 at 60 s. A region with a deposition thickness coefficient below 0.3 is located on the side of the leading edge. The area of the region increases with the increases of the inclination angle and blowing ratio. Compared with the deposition thickness of 0°, 20°, and 40° inclination angles, the deposition thickness of 60° inclination angle is the least with the blowing ratios of 0.5,1.0 and 1.5. The difference in deposition thickness at 60° and 20° inclination angles is 0.3 % with the blowing ratio 2.0. The inclination angle has little effect on the deposition thickness under the blowing ratio of 2.0. The cooling effectiveness decreases with the increases in the blowing ratio and inclination angle. The deposition thickness at a 60° inclination angle is lower than that at a 40° inclination angle. The best combination of inclination angle and the blowing ratio is 60° and 2.0 compared with others.
Open Access: Yes
The Integration of Building Information Modelling and Life Cycle Assessment: Progress, Challenges, Future Directions
Publication Name: Chemical Engineering Transactions
Publication Date: 2024-01-01
Volume: 114
Issue: Unknown
Page Range: 409-414
Description:
Building Information Modelling (BIM) plays a key role in the digitisation of the building sector, facilitating the design and construction of buildings. Environmental impacts have become an important factor to consider in building design and construction, often analysed through Life Cycle Assessment (LCA). The integration of BIM and LCA is crucial for supporting sustainable building design and construction. However, there is a lack of up-to-date reviews that consider the role of artificial intelligence (AI) in the integration of BIM and LCA. This paper addresses this gap by examining the recent progress, challenges, and future directions in building carbon emission accounting for buildings. The integration of the BIM-LCA for environmental impact accounting is explored, including goal and scope definition, life cycle inventory, impact assessment, interpretation, interoperability, and integration AI. The results identify gaps in BIM-LCA integration, including transparency issues and reliance on non-local databases. Future directions emphasise enhancing data quality, refining models, and developing AI methods for carbon emission predictions to explore decarbonisation strategy in the building sector. The review contributes to early-stage analysis, facilitating informed decision-making in sustainable building design and construction.
Open Access: Yes
DOI: 10.3303/CET24114069
Getting the priorities straight: resource use, emissions, impacts, avoidable/unavoidable waste
Publication Name: Clean Technologies and Environmental Policy
Publication Date: 2023-12-01
Volume: 25
Issue: 10
Page Range: 3129-3130
Description:
No description provided
Open Access: Yes
Process synthesis considering sustainability for both normal and non-normal operations: P-graph approach
Publication Name: Journal of Cleaner Production
Publication Date: 2023-08-15
Volume: 414
Issue: Unknown
Page Range: Unknown
Description:
Process synthesis usually determines the normal operation of the process. In addition to the cost, recently, sustainability has also become essential in selecting the process. In case of failures of some redundant operating units of the process, it may still be operational as a non-normal operation. This work shows that the sustainability performance of a process in non-normal operation can be much worse than that of the normal case. Consequently, during process synthesis, it is essential to consider the sustainability of a process for both normal and non-normal operations. The current work is the first in offering synthesis of a process network taking into account a pre-specified limit of the process sustainability indicator for both normal and non-normal modes. This synthesis procedure is formulated in a general way, to interface with any sustainability indicator, expressed as a scalar, here Sustainable Process Index has been used in the case studies. The presented method is illustrated on two case studies to showcase the capability of synthesizing processes for multiple operation. The obtained results indicate that it is possible to simultaneously reduce environmental impact and process cost by more than 20%, by appropriate modification of the operating modes.
Open Access: Yes
Reducing resource use and emissions by integrating technology and policy solutions
Publication Name: Clean Technologies and Environmental Policy
Publication Date: 2022-01-01
Volume: 24
Issue: 1
Page Range: Unknown
Description:
No description provided
Open Access: Yes
Multi-period natural gas pipeline scheduling optimisation integrated with LNG cold energy cascade utilisation
Publication Name: Sustainable Energy Technologies and Assessments
Publication Date: 2025-11-01
Volume: 83
Issue: Unknown
Page Range: Unknown
Description:
Liquefied Natural Gas (LNG), as a vital form of natural gas resources, has exhibited a steadily increasing trend in global production and trade volumes. LNG terminals are facing the challenge of how to recover and utilise cold energy in a safe and efficient regasification process, while coordinating with the natural gas pipeline network transport scheduling. This study proposes an integrated regulation and collaborative optimisation approach for natural gas pipeline networks and LNG cold energy cascade utilisation systems. For natural gas pipeline network systems, P-Graph develops multi-period gas-electric interconnected supply chain network to optimise resource allocation. For the LNG cold energy cascade utilisation system, a dual Organic Rankine Cycle (ORC) framework for both power generation and refrigeration is developed, as well as thermodynamic analysis and heat integration techniques are applied to optimise system efficiency. Using a coastal LNG terminal in Zhejiang, China, as a case study, when the LNG regasification flow rate is 62.46 t/h, cold energy generates electricity of 2,335.94 kW and air-conditioning cooling load of 1,651.5 kW, system efficiency reaches 44.75 %. The peak regulation and gas storage effect of LNG is significant, which helps to alleviate that energy shortage in the region, and the coupled system of LNG and natural gas pipeline network improves energy utilisation efficiency and economic benefits for LNG industry chain.
Open Access: Yes
Prediction of biochar physicochemical properties based on biomass initial conditions and pyrolysis process supported by data-driven multiple linear regression model
Publication Name: Energy
Publication Date: 2025-12-15
Volume: 340
Issue: Unknown
Page Range: Unknown
Description:
Biochar has gained attention for its role in soil improvement and environmental remediation. Predicting its physicochemical properties from various biomass sources is essential for optimising its applications. Existing linear regression models have investigated the effects of biomass type and pyrolysis conditions on biochar physicochemical properties and soil quality. The models are highly specific and lack predictive accuracy with limited biomass classifications. This study develops a multiple linear regression model, integrating Principal Component Analysis (PCA) to reduce dependent variables and enhance predictions of key biochar properties: pH, Cation Exchange Capacity (CEC), and Electrical Conductivity (EC). Three classification approaches—uncategorised (Combination UC), lignocellulosic analysis (Combination LA), and elemental analysis (Combination EA)—were compared. Classification significantly improved prediction accuracy, with Combination EA outperforming Combination LA. Applying PCA to Combination EA (EAPCA) further enhanced model efficiency, achieving high adjusted R2 values for pH, EC, and CEC in woody (0.817, 0.537, 0.875), herbaceous (0.795, 0.759, 0.732), and wet biomass (0.76, 0.787, 0.607) categories. The woody biomass case exhibited the strongest predictive performance for CEC. Key parameters identified through PCA included residence time, heating rate, nitrogen, hydrogen, and H/C ratio. The model's RMSE (15.4778) and R2 (0.875) indicate strong predictive capability, explaining 87.5 % of the variance in CEC. This study highlights the effectiveness of classification and PCA in improving biochar property predictions.
Open Access: Yes
Successive Mechanical Recycling of Poly(lactic Acid) by Injection Molding: Evolution of Molecular, Thermal, and Mechanical Properties
Publication Name: Macromolecular Materials and Engineering
Publication Date: 2026-03-01
Volume: 311
Issue: 3
Page Range: Unknown
Description:
This study evaluated the changes in the molecular structure, as well as the thermal and mechanical properties of poly-lactic-acid (PLA), during successive closed-loop mechanical recycling through injection molding. Gel permeation chromatographic (GPC) analyses revealed a gradual decrease in molar mass (MM); after ten recycling steps, the MM of PLA was reduced to one-third of its initial value. According to differential scanning calorimetric (DSC) measurements, both the glass transition temperature and the cold crystallization temperature of PLA decreased, while the crystallization was facilitated by the successive recycling steps. This was ascribed to the improved chain mobility resulting from the reduced MM. Quasi-static mechanical properties were evaluated using tensile tests, while impact toughness was assessed through Charpy tests. The tensile strength of PLA was not significantly affected by recycling until the fifth recycling step, where it suffered a slight (∼5%) reduction. Meanwhile, Young's modulus, elongation at yield, and impact strength remained approximately the same as the freshly injected sample at that point. However, after ten recycling steps, all analyzed properties declined significantly: Young's modulus by 11%, tensile strength by 68%, elongation at yield by 63%, and impact strength by 30%.
Open Access: Yes
Selection of Heat Transfer Enhancement Technique for Compact Mini and Micro Heat Exchangers Design
Publication Name: Chemical Engineering Transactions
Publication Date: 2025-01-01
Volume: 120
Issue: Unknown
Page Range: 475-480
Description:
The need to decrease the sizes and masses of heat exchangers while preserving their performance has stipulated the development of compact heat exchangers with mini and micro channels (MCHE). It is supported by the need for increased recuperation of heat energy, facilitating better energy efficiency with strict limitations for space, material and cost. The adequate substitution of conventional heat exchangers with MCHE requires maintaining the same heat load, not exceeding the allowable pressure losses. The different ways to increase the compactness are analysed, including the change of hydraulic diameter, and the use of various methods of heat transfer intensification by changing the channel geometry and flow structure. The Nusselt numbers and friction factors correlations for plane tubes and criss-cross flow channels of plate heat exchangers are compared. A newer form of the core velocity equation has been developed, which allows comparison of the performance of MCHE heating surfaces with different enhancement techniques in specific process conditions. The results of the calculations illustrate the influence of the channel's hydraulic diameter and length on the MCHE performance for channels with the considered methods of heat transfer intensification. The ways to decrease channel size to mini and micro scales are determined. The recommendations on choosing the best channel geometry and size, depending on specified process conditions and stream nature, are formulated.
Open Access: Yes
DOI: 10.3303/CET25120080
Comparative Life Cycle Assessment of Alternative Fuels for Transport Sector Decarbonisation
Publication Name: Journal of Sustainable Development of Energy Water and Environment Systems
Publication Date: 2025-12-01
Volume: 13
Issue: 4
Page Range: Unknown
Description:
Decarbonising the transport sector is crucial, yet selecting the most suitable alternative fuels remains challenging. This study applies life cycle assessment to evaluate six alternative fuels, such as hydrogen, compressed natural gas, methanol, ethanol, Fischer-Tropsch gasoline, and diesel, against conventional gasoline, diesel, and grid electricity, focusing on global warming potential and acidification potential. Emissions were analysed using the Greenhouse gases, Regulated Emissions, and Energy use in Technologies model under two scenarios: current technologies (2025) and projected advancements (2050). The results indicate that, compared to gasoline, compressed natural gas reduces global warming potential and acidification potential by 27% and 23% in the short term, while gaseous hydrogen achieves reductions of 63% and 46% in the long term, respectively. These findings reinforce the theoretical foundation for transport sector decarbonisation and contribute to its sustainable development. Future research will broaden the assessment framework by incorporating complete vehicle life cycle analysis, evaluating additional alternative fuels, and integrating a wider set of indicators.
Open Access: Yes
Creation of Slag-Containing Composite Material Prototypes Using Powder Metallurgy Methods
Publication Name: Engineering Technology and Applied Science Research
Publication Date: 2025-10-06
Volume: 15
Issue: 5
Page Range: 26555-26563
Description:
This study explores the powder metallurgy methods for obtaining slag-containing composite materials that can be utilized in the ceramic industry, and especially in catalysis, as raw materials for the production of building materials, and also as refractories. The main components of the synthesized samples of composite materials are natural aluminosilicates from the east of Kazakhstan and metallurgical slag of lead production. Varying the content of components in the range: slag 10-30 wt.%, bentonite clay 30-40 wt.%, and natural zeolite 40-60 wt.%, a pilot batch of composite materials was obtained. The results show that the samples had high mechanical strength, ranging from 20.7 to 50.53 MPa, after sintering at a temperature of 1000 °C.
Open Access: Yes
DOI: 10.48084/etasr.11991
A Systematic Review of Life Cycle Assessment Reporting Practices and Transparency for Mono-Crystalline Silicon Photovoltaic Systems
Publication Name: Chemical Engineering Transactions
Publication Date: 2025-01-01
Volume: 122
Issue: Unknown
Page Range: 97-102
Description:
Mono-crystalline silicon (mono-Si) PV modules account for around 70 % of global c-Si production, making robust environmental assessments essential. Life Cycle Assessment (LCA) is widely used for this purpose, yet inconsistent data reporting limits transparency and comparability. While prior reviews have explored environmental impacts and parameter trends, none have systematically evaluated reporting quality in mono-Si PV LCAs. To address this, the current review conducted a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-guided review of 32 mono-Si PV LCA studies published from 2019 to 2024. Each was assessed using the ISO 14040/14044 framework and IEA guidelines, with a focus on key elements such as functional unit, system boundary, data sources, software, characterization models, and data quality analysis. The review applied both a descriptive summary of common practices and a grading rubric to evaluate reporting transparency. Results reveal major inconsistencies, with fewer than half of the studies meeting international standards. This underscores the urgent need for harmonized reporting protocols in mono-Si PV LCA literature.
Open Access: Yes
DOI: 10.3303/CET25122017
Thermal-hydraulic performance of heat exchanger mini- and micro-channels with single-phase flows. A comprehensive review and a comparative study
Publication Name: Renewable and Sustainable Energy Reviews
Publication Date: 2026-04-01
Volume: 230
Issue: Unknown
Page Range: Unknown
Description:
The efficient use of energy is a prerequisite for the sustainable development of modern society. It requires increasing heat recuperation in various energy-reliant systems, which is possible with heat transfer devices of intensive action, operating in conditions of limited space for installation and material availability for their production. This is achieved by heat exchangers with mini- and micro-channels, regarded as the next generation of heat transfer equipment. A survey of publications on heat transfer and pressure losses in mini- and microchannels is presented, with focus on their thermal-hydraulic performance. It includes straight channels of various cross-sectional forms, channels with enhanced heat transfer for electronic cooling, additively manufactured microchannels, crisscross flow channels of microturbine recuperators, and plate heat exchangers. A novel Micro Heat Factor for the comparison of mini- and microchannels thermal-hydraulic performance is derived. For the detailed estimation of channel performance in specified process conditions, accounting for the differences in hydraulic diameters, the equation for optimal fluid velocity is proposed. The comparison of thermal-hydraulic performance for different types of mini- and micro channels is performed, and the possibilities of their use in heat exchangers at specific applications are discussed, followed by directions of future studies.
Open Access: Yes
Systematic generation of flexible heat exchanger networks with minimum utility consumption
Publication Name: Thermal Science and Engineering Progress
Publication Date: 2026-02-01
Volume: 70
Issue: Unknown
Page Range: Unknown
Description:
Heat exchanger network (HEN) synthesis is a topic of high importance, encompassing several solution approaches and problem aspects. One such aspect crucial to industrial applications is flexibility, since real systems often experience variations of certain parameters, e.g., inlet temperatures or flowrates. Decades of research have revealed numerous methods for analyzing the flexibility of a given heat exchanger network. Meanwhile, the synthesis of flexible HENs continued to prove to be a severely difficult task, especially since handling the parameter deviations should not compromise the high level of heat integration. This work introduces a novel direction for synthesizing flexible HENs by combining flexibility analysis methods with P-graph-based, exhaustive, combinatorial network generation. The method generates all feasible networks that satisfy both the structural criteria and the maximum energy recovery over the entire variation region, and presents them ordered by capital cost. This first iteration of the work focuses on variations in inlet stream temperatures. This allows proving the validity of the underlying concepts by generating HENs that achieve minimum utility consumption for the entire range of temperature variations. The capability to generate multiple suitable networks is demonstrated through a case study, where 429 feasible networks were generated, which are all capable of achieving maximum heat integration within the parameter variation region. For the best generated design options, a 4–6% increase in capital cost compared to the base case is sufficient to satisfy the flexibility requirements.
Open Access: Yes
Optimal Planning of Routes, Schedules, and Charging Times of Automated Guided Electric Vehicles
Publication Name: Energies
Publication Date: 2026-02-01
Volume: 19
Issue: 3
Page Range: Unknown
Description:
In traditional industry setups, Automated Guided Vehicles (AGVs) follow trajectories planned together with the layout of the storage or production facility and supported by fixed markers on the floor or on the walls. Traffic rules manage the avoidance of multiple vehicles, while fleet management gets movement and transportation commands completed as soon as possible. In contrast, recent developments in navigation and advanced computing, sensor, and communication capabilities make their free movement safe and manageable. Detailed route planning and scheduling can guarantee that the vehicles keep a safe distance in time and space. A recent challenge of electric AGVs is that their charging may take several hours, which must be factored into their schedule. This has made minimal energy demand a key objective alongside earliest delivery and strictly meeting the deadlines. This paper presents a method for detailed routing and scheduling of AGV fleets to minimize energy consumption while considering battery levels and charging times. The optimization method is illustrated by a case study where multiple delivery tasks are performed by synchronized movement of vehicles on a complex warehouse layout. In the optimal solution, the scheduled waiting times for collision avoidance are utilized by the vehicles to pre-charge their batteries.
Open Access: Yes
DOI: 10.3390/en19030813
Pinch analysis for sustainable development: A cross-disciplinary review of developments from 2018 to 2025
Publication Name: Renewable and Sustainable Energy Reviews
Publication Date: 2026-07-01
Volume: 235
Issue: Unknown
Page Range: Unknown
Description:
Since the 1970s oil crisis, Pinch Analysis (PA) has been employed as a heat recovery guidance tool to address the need for energy conservation. With the continuous improvement of the theoretical system and the ongoing innovation of the methodology, PA has not only been deepened and developed within the energy domain but has also been extended to other important problem domains, enabling optimal resource utilisation and becoming an indispensable analytical methodology for the integration of process industries. This review builds upon a critical review published in 2018 and summarises the recent advancements (2018 to the present) of PA in the domains of process modelling and energy optimisation, energy system process integration, resource network optimisation, freshwater integration, carbon emissions integration, plastics management networks, and energy-water-carbon nexus. It also summarises the tools used by PA methods and looks at the future development of PA in various fields. The main findings of this review are: 1) PA has evolved in recent years towards multi-methodology, multi-dimensionality and multi-objectives, as well as a greater focus on dynamic adaptability when dealing with complex application scenarios; and 2) according to the reported data of works reviewed in this paper, a diversified and effective tool chain and specialised tool (e.g. Aspen, Water Pinch, CEPA) can achieve up to 75% savings in energy consumption and resources in specific industrial cases.
Open Access: Yes
