Heat Utilization Research Articles

Life Cycle Assessment of Primary Aluminum Production

Life cycle assessment (LCA) is used to quantitatively analyze the energy consumption and environmental impact of primary aluminum production in China, the United States, and Europe, as well as global average. The results indicate that electricity and fuel contribute more than 60% of the environmental impact of bauxite mining; steam is the greatest contributor to the environmental impact of alumina production by the Bayer process, with a result exceeding 35%; and electricity contributes >50% of the environmental impact of aluminum electrolysis. The environmental impact of primary aluminum production in China is 1.2 times the global average. The contributions of the three stages of primary aluminum production to the total environmental impact of the process in China are, in descending order, aluminum electrolysis (64.33%), alumina production (33.09%), and bauxite mining (2.58%). If the proportion of thermal power in the electricity source structure is reduced from 60% to 0%, the contribution of electricity to the environmental impact of primary aluminum production will decrease from 38% to 2%, and the total environmental impact will decrease by 73%. Therefore, energy conservation and emissions reduction can be realized through the optimization of the power generation structure, adoption of clean energy production, and improvement of the heat utilization rate in production processes.

Research on power generation and waste heat utilization performance of a novel gas-CO2 combined cycle

Research on power generation and waste heat utilization performance of a novel gas-CO2 combined cycle

Biomass Gasification as a Viable Alternative for Small-scaled Combined Heat and Power Technologies in Remote Communities in Canada

The use of forest biomass could drastically reduce the environmental impacts of fossil fuel usage for heat and power in remote communities and can provide new opportunities for employment, retaining money inside communities. Here, we present the techno-economic feasibility of alternative gasification technologies for CHP uses in three remote off-grid communities in Canada. The analysis includes different scenarios of fuel price and operation costs, as well as two different feedstocks, wood pellets and wood chips. The results show potential for successful implementation, subject to planning on the specific conditions and location of the community. Power generation costs vary widely depending on the available biomass price, utilization of heat as well the power output of the system, ranging from about 0.25 CAD/kWh to over 1.20 CAD/kW. Economic support for biomass or removal of diesel subsidies would have a significant impact on biomass CHP implementations. The feasibility of the investigated systems is not dependent on the economics or technology itself but (i) availability of quality feedstock, (ii) utilization of heat for additional revenue generation, (iii) the utilization of the systems, (iv) community-driven bioeconomy alternatives and (v) carbon credit opportunities.

Targeted Minimum Quantity Fluid Application in Machining

The surface integrity of a machined component is crucial for its service life part. One of the main final specifications that a machined part is inspected for is the surface integrity metrics, including surface residual stresses, surface microhardness, surface roughness, and microstructure. In this paper, the cutting fluid is strategically targeted to utilize heat energy effectively in the primary, secondary, and tertiary shear zones to positively affect the surface integrity metrics and machining mechanics. In this study, a lower quantity of the cutting fluids is targeted at the high-temperature zones to reduce the machining temperatures, thereby effectively simulating the effect of a ‘flood coolant’. The cutting fluid is applied simultaneously as a targeted Minimum Quantity Fluid (MQF) on the cutting tool’s flank and rake faces to improve the surface integrity metrics and chip formation. Also, this study analyzes the effect of the cutting fluid composition, the type of cutting fluid, and the amount of fluid quantities. The machining-induced surface integrity metrics are analyzed to understand the effects of targeted minimum quantity fluid application. The impact of the targeted application of cutting fluid on machining mechanics metrics, such as cutting forces and chip formation, is analyzed. Applying a targeted MQF application at the flank face of the cutting tool leads to higher compressive subsurface principal residual stresses. The results indicate that using MQF on both the flank and rake faces simultaneously enhances the surface integrity. The effect of a cutting fluid jet on the flank face is modeled to highlight the thermophysical properties that are crucial for selecting the appropriate cutting fluid to lower the machining-induced temperatures. With targeted MQF application, the fluid jet acts as a dynamic and external chip control mechanism. Overall, effectively managing temperatures in machining could enhance subsurface residual stresses and surface roughness using various cutting fluid combinations. Also, this paper presents a targeted cutting fluid application that improves the microstructural formation, enhancing chip control and producing machined surfaces and components with better surface integrity.

Multi-Objective Optimization of a Hybrid Fossil/Renewable Carbon Methanol Cluster.

Replacing fossil carbon- with renewable carbon-based technologies is imperative for transitioning to sustainable chemical production. However, most production pathways based on renewable carbon are currently economically unappealing. Here, we show that hybrid clusters exploiting synergies between different fossil and renewable carbon-based processes in terms of heat, mass, and power integration could make defossilized chemical technologies more competitive. We consider an integrated carbon cluster based on fossil and renewable carbon feedstocks for methanol production, including a novel oxy-combustion cycle for purge gas treatment and power generation. Using multiobjective optimization considering economic and environmental criteria (i.e., unitary production cost and global warming potential (GWP) impact, respectively), we find that integrated clusters could reduce the cost of carbon-neutral methanol by up to 30%, while leading to reductions in GWP impact from 21 to 142% for a given unitary production cost target, and heating utility savings between 80 and 100%. We conclude that hybridization of fossil and renewable technologies could become instrumental in enabling a gradual shift toward sustainable chemical production pathways.

Comparison of Molten Salts and Thermal Oil in Parabolic Trough Power Plants for Different Sites and Different Storage Capacities

This study compares the levelized cost of energy (LCOE) of parabolic trough solar power plants using thermal oil or two different molten salt mixtures located at three different sites and with different thermal storage capacities. The necessity of using appropriate model approaches for the temperatures along a loop of the solar field is discussed, as well as the utilization of heat from thermal storage for freeze protection of the molten salt plants. The ternary salt mixture with a lower temperature limit of 170 °C and an upper temperature limit of 500 °C shows the lowest LCOE for all sites and almost all investigated storage capacities. Molten salts as heat transfer fluids are particularly favorable for sites with high irradiation and plants with large storage capacities of more than six full load hours.

A Two-Stage Robust Optimization Strategy for Long-Term Energy Storage and Cascaded Utilization of Cold and Heat Energy in Peer-to-Peer Electricity Energy Trading

This study addresses the optimization of urban integrated energy systems (UIESs) under uncertainty in peer-to-peer (P2P) electricity trading by introducing a two-stage robust optimization strategy. The strategy includes a UIES model with a photovoltaic (PV)–green roof, hydrogen storage, and cascading cold/heat energy subsystems. The first stage optimizes energy trading volume to maximize social welfare, while the second stage maximizes operational profit, considering uncertainties in PV generation and power prices. The Nested Column and Constraint Generation (NC&CG) algorithm enhances privacy and solution precision. Case studies with three UIESs show that the model improves economic performance, energy efficiency, and sustainability, increasing profits by 1.5% over non-P2P scenarios. Adjusting the robustness and deviation factors significantly impacts P2P transaction volumes and profits, allowing system operators to optimize profits and make risk-aligned decisions.

Improving yield and heat use efficiency of broccoli (Brassica oleracea L. var italica) grown under abiotic stresses in the mid-hill of Himachal Pradesh

A field experiment was conducted in the mid-hill zone of Himachal Pradesh representing the sub-humid zone to study the phenological behaviour and heat use efficiency of broccoli crop under abiotic stresses. The broccoli variety, Sakata was evaluated under three thermal environments (T1- 8th October, T2 -28th October and T3- 18th November). To expose the crop to different thermal environments, two mulching levels (M1-with black mulch and M2- without mulch) and two irrigation levels (I1- Irrigation at different phenological stages I2- rainfed conditions), during rabi season of 2021-22. The experiment was laid out in a factorial randomized complete block design with three replications. Different agroclimatic indices were computed viz., accumulated growing degree days, helio-thermal units, photothermal units and heat use efficiency. The regression models were developed between the agroclimatic indices, yield and dry matter accumulation of crop. It was found that the broccoli crop sown on 28th October (the normal date of transplanting) took maximum (132) days to reach maturity. The number of days required to attain different phenological stages decreased with delayed sowing. The accumulated growing degree days requirement at the harvesting stage (921.4 ºC day) was observed maximum in timely transplanted (28th October) crop resulting in a higher yield per plot (10.4 kg) and decreased with late transplanted (18th November) crop. The crop utilized heat more efficiently under a timely sown crop. The highest heat use efficiency (HUE) was observed in the crop sown on 28th October and 8th October (27.37 and 25.35 kg/ha/°C/day), respectively. The regression models were developed between curd yield, dry matter accumulation and thermal units of the crop. The model explained 0.50, 0.44 and 0.47 variations in curd yield whereas 0.69, 0.58 and 0.63 variations in dry matter accumulation with different agroclimatic indices under different transplanted dates, mulching and irrigation levels respectively. Broccoli cultivation yielded a profit of ?5.17 lakhs/ha, demonstrating its profitability for farmers. The study highlighted that timely sowing, black mulch, and optimal irrigation significantly improved heat utilization efficiency in mid-hill sub-humid regions. Black mulch improved soil moisture and temperature, creating ideal conditions for broccoli, a thermo-sensitive crop.

Analysis of carbon reduction potential from typical municipal solid waste incineration plants under MSW classification.

The disposal of municipal solid waste (MSW) is a significant source of greenhouse gas (GHG) emissions. As incineration becomes the primary method of MSW disposal in China, MSW incineration (MSWI) plants are expected to play a crucial role in mitigating GHG emissions in the waste sector. This study estimated the quarterly GHG emissions from two representative MSWI plants in Qingdao using a life-cycle assessment (LCA) approach. Additionally, the potential for GHG emissions reduction in MSWI was explored. The findings indicated that, in 2022, the GHG emission intensity for plants A and B were 56.55 and 96.73kg CO2-eq/t MSW, respectively. The fluctuating composition of MSW, particularly the proportions of recyclables and food waste, could significantly impact GHG emissions from MSWI. Surprisingly, a negative correlation was observed between net GHG emissions and the recycling efficiency of recyclables, suggesting that improving the sorting efficiency of recyclables may not yield substantial carbon reduction advantages for the final incineration of MSW. The utilization of waste heat for heating presented a higher potential for carbon reduction compared to incineration for power generation. Consequently, the reuse of residual steam heat, the application of carbon flue gas capture technology, and proper co-combustion with industrial solid waste or municipal sludge are viable strategies for mitigating GHG emissions from MSWI plants.

Investigation on the Application of Carbon Dioxide Power Generation Cycles in Solar Energy Heating Utilization

Investigation on the Application of Carbon Dioxide Power Generation Cycles in Solar Energy Heating Utilization

A novel one-way oscillating flow cycle engine with characteristic of large temperature glide heat addition for low-grade heat utilization

A novel one-way oscillating flow cycle engine with characteristic of large temperature glide heat addition for low-grade heat utilization

The modelling of a multi-tubular packed-bed reactor for ammonia cracking and SOFC waste heat utilization

The modelling of a multi-tubular packed-bed reactor for ammonia cracking and SOFC waste heat utilization

Utilizing biomass-derived activated carbon hybrids for enhanced thermal conductivity and latent heat storage in form-stabilized composite PCMs

ABSTRACT In this study, the focus was on developing multifunctional organic form-stabilized composite phase change materials (PCMs) to efficiently manage thermal energy and promote sustainable energy utilization. The novel composite PCMs were designed and synthesized by incorporating Methyl stearate (MtS) as the PCM with pristine activated carbon derived from coconut shells (CAC) and thermally enhanced CAC@Graphene nanoplatelets (GnP) hybrid matrices. Particularly, the combination of CAC90@GnP10/MtS allowed the composite PCM to exhibit excellent thermophysical responses, capitalizing on the unique properties and synergistic effects of each component. The resulting composite PCM from this combination demonstrated remarkable performance, with a high loading ratio of 70% and a latent heat of 160.87 J/g, which is 27.52% higher than that of the pristine CAC-supported PCM. The test results indicated that the chemical and crystal structure of MtS remained unaffected after the composite formation. The thermal conductivity of CAC90@GnP10/MtS was found to be 102.85% higher than CAC/MtS and 195.83% higher than MtS alone. The enhancement in thermal conductivity was further validated through observed reductions in melting and solidification times, as well as analysis using infrared thermal imaging. In conclusion, the development of these intelligent, multifunctional composite PCMs, which utilize CAC@GnP hybrids as supporter scaffolds and thermal conductivity enhancers for MtS, holds great promise for effective sustainable energy usage and thermal energy management systems in various fields like waste heat utilization, energy-saving buildings, constant temperature protection, thermal management of electronic devices, aerospace industry, textiles, automotive, and renewable energy systems.

Utilization of Heat from The Reactor's Outlet Stream in Formaldehyde Production to Reduce Energy Usage in The Heat Exchanger

Global production of formaldehyde has consistently risen over the past ten years, highlighting its extensive industrial applications and high demand across various sectors worldwide. However, its production continues to consume a significant amount of energy. The aim of this paper is to investigate and propose strategies for enhancing energy efficiency in formaldehyde production processes. Specifically, the study focuses on harnessing heat from the reactor's outlet stream to minimize the energy consumption associated with heat exchangers. By analyzing and optimizing the utilization of this heat source, the paper aims to contribute to sustainable manufacturing practices by reducing overall energy requirements and operational costs in formaldehyde production facilities. The process modification was simulated using Aspen HYSYS and the comparison of net-energy between the basic and the modified process is calculated using the net-energy formula. The results obtained that the Net-Energy (NE) value for both basic and modified process is 316,286,815.4 kJ/h and 125,757,792.9 kJ/h. This shows that the modified process has better energy efficiency compared to the basic process as the net-energy value zero. Therefore, this modification enhances the energy efficiency of the formaldehyde production process through methanol oxidation. Copyright © 2024 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Description and Optimization of Gas Turbine Generator Sets

Form this article, the author mainly interprets the principle and composition of gas turbine generator set, as well as discusses how to improve efficiency and treat exhaust gases, which including compressor interstage waste heat utilization for power generation, auxiliary catalytic technology and gas-steam turbine combined cycle. Taking the Rankine cycle based on compressor interstage waste heat as an example, it discusses how to recover and utilize the compressor interstage waste heat; through the analysis of the waste heat recovery system, it is concluded that the auxiliary catalytic technology plays an vital role in the operation of internal combustion engines; the analysis of the principle of the gas turbine combined cycle and the comparison of two kinds of combined cycles result in the conclusion that the gas-steam turbine combined cycle is a highly efficient and feasible means of optimizing the efficiency of the system. After exploring the three aspects, the author of this essay has finally come up with three reliable paths for optimizing gas turbine generator sets.

Investigation of Combine Cycle Power Plants with Low-Grade Heat Utilization Working Methane-Hydrogen Mixtures

The Russian energy sector remains heavily reliant on thermal power plants, with gas generation accounting for approximately 66% of the installed capacity. However, the industry faces challenges such as depletion of reserves, rising prices for hydrocarbons, and increasing concentrations of carbon dioxide in the atmosphere. This study focuses on developing new scientific and technical solutions to increase the efficiency and environmental safety of combined cycle power units. The research involves structural and parametric optimization of trinary cycle power plants operating on a methane-hydrogen mixture, as well as the development and optimization of turbine and heat exchange equipment for low-temperature power plants. The results show that the transition to trinary CCGT (Combine Cycle Gas Turbine) units with deep utilization and the use of hydrogen fuel can significantly reduce specific CO2 emissions and increase energy efficiency up to 0.21% with also increases in capacity of turbine of approximately 17 MW. The aim of this research is to calculate the efficiency, cost effectiveness and environmental-friendly solution for power generation using mixture of hydrogen- methane as fuel in combine cycle power plant that includes ORC. Additionally, the efficiency of the organic Rankine Cycle (ORC) benefits from the increased moisture, with capacity improvements of 1-2 MW observed when the hydrogen proportion rises from 25% to 50%. Moreover, the potential for zero emissions, coupled with significant increases in power output and efficiency, underscores hydrogen's role as a pivotal component in the future of energy production.

Optimization of the Drying Process for Gamma-Irradiated Mushroom Slices Using Mathematical Models and Machine Learning Algorithms

Concerns over dried product quality and energy consumption have prompted researchers to explore integrated techniques for improving quality and reducing energy use. This study investigates the effect of gamma irradiation pretreatment (0, 1.2, 2.4, and 3.6 kGy) on button mushroom slices, followed by thin-layer drying at 50, 60, and 70 °C. The results indicated that increasing irradiation dose and drying temperature significantly reduced drying time. The Midilli model provided the best fıt to the drying data (R2 = 0.9969–0.9998). Artificial neural networks (ANN) accurately predicted moisture variations, achieving R2 = 0.9975 and RMSE = 0.0220. The Support Vector Machine (SVM) algorithm, employing the Pearson universal kernel in normalized mode, also performed well, with R2 = 0.9939 and RMSE = 0.0344. Similarly, in the k-nearest neighbors (kNN) algorithm with three neighbors (k = 3), the R2 and RMSE values were 0.9888 and 0.0458, respectively. Gamma irradiation enhanced the effective diffusion coefficient (Deff) to 10.796 × 10−8 m2/s, and reduced activation energy (Ea) to 11.09 kJ/mol. The highest heat utilization efficiency (41.1%) was observed at 3.6 kGy and 50 °C. These findings highlight the potential of integrating gamma irradiation pretreatment and advanced drying techniques to optimize energy use and improve the quality of dried mushroom slices.

Thermodynamic Analysis and Optimization of Power Cycles for Waste Heat Recovery

Improvement of energy efficiency in technological processes at industrial enterprises is one of the key areas of energy saving. Reduction of energy costs required for the production of energy-intensive products can be achieved through the utilization of waste heat produced by high-temperature thermal furnace units. Generation of electric power based on the waste heat using power cycles with working fluids that are not conventional for large power engineering, may become a promising energy saving trend. In this paper, thermodynamic analysis and optimization of power cycles for the purposes of waste heat recovery are performed. The efficiency of combining several power cycles was also evaluated. It has been established that the combination of the Brayton recompression cycle on supercritical carbon dioxide with the organic Rankine cycle using R124 allows for greater electrical power than steam-power cycles with three pressure circuits under conditions where the gas temperature is in the range of 300–550 °C and the cooling temperature of is up to 80 °C. Additionally, when cooling gases with a high sulfur and moisture content to 150 °C, the combined cycle has greater electrical power at gas temperatures of 330 °C and above. At enterprises where the coolant has a high content of sulfur compounds or moisture and deep cooling of gases will lead to condensation, for example, at petrochemical and non-ferrous metallurgy enterprises, the use of combined cycles can ensure a utilization efficiency of up to 45%.

Economic Analysis of a Hybrid Solar-Biogas Refrigeration System for Dairy Applications

This study investigates the performance and economic feasibility of a hybrid solar-biogas-powered vapour absorption refrigeration system tailored for dairy applications. Refrigeration is essential for preserving dairy products, and the integration of renewable energy sources offers a sustainable alternative to conventional methods. A 50-liter capacity hybrid refrigeration system was designed, utilizing heat energy derived from solar radiation and biogas combustion. The system's performance was assessed through experimental tests under varying conditions, and its coefficient of performance (COP) was evaluated for full-load scenarios. The economic analysis focused on parameters such as net present value (NPV), benefit-cost ratio (BCR), internal rate of return (IRR), and payback period. Results indicate that the hybrid system offers substantial energy savings and environmental benefits. Among the approaches analyzed, the solar water heater and biogas combination demonstrated the highest economic returns, although the biogas-only system proved more practical in maintaining the required generator temperatures. This study underscores the potential of hybrid energy systems in advancing sustainable refrigeration solutions.

Enhancing the efficiency of solar-powered water distillation units by utilization of waste heat

ABSTRACT Thermal water desalination is based on the evaporation and condensation of water, and such a process consumes a lot of energy, which lowers the economy of the process for commercial water desalination. The objective of this research is to improve the desalination energy efficiency of a novel domestic water desalination unit, which is based on thermal desalination, and this is done via utilization of the waste heat in the generated steam and reducing the operating costs. The distillation process begins with solar-powered evaporation of the salty water in the evaporator, followed by condensation of the generated water vapor coming from the evaporator over the cross-flow heat exchangers located in the condenser, which preheats the incoming saline water from the saltwater tank before it enters the evaporator. To assess the system's performance, comprehensive measurements are taken, including the electrical energy output from the PV panels and the volume of the output distilled water. Notably, the energy efficiency of the distillation is defined as the ratio of the heat energy gained by the distilled water, i.e. collected at the end of the day, to the electrical energy input to the electric heater, and it is found to be, on average, 82%.