Tingpu He , Jianqin Fu , Yaorui Shen , Boquan Qin , Changhe Wei
{"title":"Effect of injection strategies and EGR on combustion characteristics of GDI Atkinson cycle engine","authors":"Tingpu He , Jianqin Fu , Yaorui Shen , Boquan Qin , Changhe Wei","doi":"10.1016/j.tsep.2025.103544","DOIUrl":"10.1016/j.tsep.2025.103544","url":null,"abstract":"<div><div>The sweeping tests for exhaust gas recirculation (EGR) rates and different injection strategies (injection ratio and injection timing) were conducted on a gasoline direct injection (GDI) Atkinson cycle engine (ACE). The influences of above factors on thermodynamic, combustion and emission features of ACE were investigated. The results showed that larger EGR rate may not obtain better performance and the optimal condition occurs at the EGR rate of 7 %. At the EGR rate of 0 % and 7 %, the brake specific fuel consumption (BSFC) is respectively decreased by 4.18 g/(kW·h) and 3.64 g/(kW·h) by replacing single injection with double injection. As the second injection ratio (SIR) increases, the ignition delay is inevitably prolonged and heat release process is slowed down, leading both NOx and HC to decline but CO to ascend. The effect of second injection timing (SIT) on operating parameters enlarges significantly at the larger SIR. The later SIT deteriorates combustion and harms the fuel economy of ACE consequently, resulting in sharp drop in NOx emission (up to 44.9 %) but rise in other emissions. In general, the overall performance of ACE with double injection is superior to that with single injection, especially at the SIR of 0.2 at target condition.</div></div>","PeriodicalId":23062,"journal":{"name":"Thermal Science and Engineering Progress","volume":"61 ","pages":"Article 103544"},"PeriodicalIF":5.1,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Pyrolysis of Acacia nilotica bark: estimation of kinetic and thermodynamic parameters using model-free isoconversional methods","authors":"Alok Kumar Singh, Pujan Chirag Parikh, Jyoti Prasad Chakraborty","doi":"10.1016/j.tsep.2025.103525","DOIUrl":"10.1016/j.tsep.2025.103525","url":null,"abstract":"<div><div>Pyrolysis of Acacia nilotica Bark (ANB) was investigated using KAS (Kissinger–Akahira–Sunose), FWO (Flynn-Wall-Ozawa), and Starink methods to study the kinetics and thermodynamics. Thermogravimetric analysis was carried out at four heating rate 5, 10, 20, and 30 °C/min in nitrogen atmosphere. DTG curves indicating weight-loss peaks move to higher temperatures at higher heating rates. More biochar was produced at higher heating rates as the rate of weight loss slowed down at higher heating rates. The average activation energy obtained by KAS, FWO, and Starink methods were 100.30, 107.59, and 100.22 kJ/mol, respectively. The pre-exponential factors ranged from 2.75*10<sup>-2</sup> – 1.37*10<sup>15</sup> for KAS, 1.11 – 1.20*10<sup>15</sup> for FWO, and 3.27*10<sup>-2</sup> – 1.44*10<sup>15</sup> s<sup>−1</sup> for Starink. Thermodynamic characteristics of ANB indicated that it contains potential energy for bioenergy generation and could produce higher yields of biochar. Criado’s Z-master plots were constructed which depict that biomass degradation follows a multistep reaction mechanism. In the lower conversion range, it was observed that ANB decomposed using the (R2), (R3), and D2; and in the middle conversion range it followed (F2), (A4), (D4), and (D2) models and in the high conversion range it followed diffusion (R2) and (R3) model.</div></div>","PeriodicalId":23062,"journal":{"name":"Thermal Science and Engineering Progress","volume":"61 ","pages":"Article 103525"},"PeriodicalIF":5.1,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143714255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Experimental and numerical investigation of the impact of turbulence on a small-scale double-stage Savonius vertical axis wind turbine in an open environment application","authors":"Yashwant Kumar Singh , Subrata Kumar Ghosh , Tanmoy Maity","doi":"10.1016/j.tsep.2025.103540","DOIUrl":"10.1016/j.tsep.2025.103540","url":null,"abstract":"<div><div>This paper presents an experimental and numerical investigation of the impact of turbulence on a small-scale double-stage modified Savonius vertical axis wind turbine (VAWT) operating in an open environment. The study utilized wind tunnel experiments with free stream velocities of 4 ms<sup>−1</sup>, 6 ms<sup>−1</sup>, 7 ms<sup>−1</sup>, 8 ms<sup>−1</sup>, and 11 ms<sup>−1</sup>. The power and torque coefficients were measured for various wind speeds, with significant observations noted at 7 ms<sup>−1</sup>. Specifically, the maximum power coefficient (<em>Cp</em>) of 23 % was achieved for the modified Savonius turbine was at 7 ms<sup>−1</sup>, which was found to be higher compared other wind speeds, demonstrating optimal aerodynamic performance. Controlled turbulence was introduced using a turbulence-generating mechanism, with turbulence intensities ranging from 10 % to 14 %. Numerical simulations were performed to validate the experimental results, and the findings revealed that turbulence intensity influenced the aerodynamic efficiency of the turbine blades, enhancing their performance in certain conditions. Notably, under turbulent conditions at lower wind speeds 4 ms<sup>-1</sup>to 7 ms<sup>−1</sup>, the torque coefficient increased from 0.24 and 0.15 under uniform flow to 0.40 and 0.44, respectively. At higher wind speeds 8 ms<sup>-1</sup>and 11 ms<sup>−1</sup>, a slight decrease in torque coefficient was observed due to the onset of turbulent flow effects. The study advances the understanding of the turbine’s performance in turbulent environments, particularly highlighting the importance of turbulence intensity for optimizing turbine design and efficiency in urban and complex wind conditions. These results provide valuable insights for designing wind turbines capable of operating efficiently in varied and dynamic wind environments.</div></div>","PeriodicalId":23062,"journal":{"name":"Thermal Science and Engineering Progress","volume":"61 ","pages":"Article 103540"},"PeriodicalIF":5.1,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143714256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Navid Mahdavi, Animesh Dutta, Syeda Humaira Tasnim, Shohel Mahmud
{"title":"An innovative method for pinch point analysis of heat exchangers utilizing binary mixtures","authors":"Navid Mahdavi, Animesh Dutta, Syeda Humaira Tasnim, Shohel Mahmud","doi":"10.1016/j.tsep.2025.103536","DOIUrl":"10.1016/j.tsep.2025.103536","url":null,"abstract":"<div><div>Pinch point (PP) analysis is critical for integrating, designing, and improving the thermal performance of counter-flow heat exchangers (HEXs) in energy systems, particularly those utilizing binary mixtures such as ammonia-water. Traditional PP analysis methods struggle with the complexities of non-isothermal phase change behaviors, leading to inaccuracies and computational inefficiencies. This study proposes a novel and systematic approach for PP analysis that integrates mathematical and numerical techniques to determine the unknown outlet state of a target stream based on the known states and a predefined PP temperature difference that constrains the streams. The methodology employs polynomial functions of temperature-specific enthalpy relationships, transformed into dimensionless enthalpy-based expressions, enabling an iterative process to precisely identify the minimum temperature difference between streams. Verification against existing analytical and numerical methods demonstrates the superior accuracy and computational efficiency of the proposed approach. A comprehensive parametric study further reveals the impact of mass fraction, working pressure, polynomial degree, and numerical tolerance on PP characteristics. The method applies to a wide range of thermodynamic and industrial processes, such as the Kalina cycle, absorption refrigeration systems, and binary distillation, facilitating heat integration and energy recovery.</div></div>","PeriodicalId":23062,"journal":{"name":"Thermal Science and Engineering Progress","volume":"61 ","pages":"Article 103536"},"PeriodicalIF":5.1,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143747414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Experimental investigation of enhanced hydrogen production from atomised water-methanol mixture in a modified plasma reformer","authors":"Neeraj Budhraja, Amit Pal, R.S. Mishra","doi":"10.1016/j.tsep.2025.103535","DOIUrl":"10.1016/j.tsep.2025.103535","url":null,"abstract":"<div><div>Hydrogen is a clean energy carrier with a very high energy content by mass. However, about 97–98 % of H<sub>2</sub> production is through steam reforming, which lowers the benefits of cleaner fuel. In current work, a modified plasma reformer was used to enhance hydrogen production, and the performance parameters like feed flow rate (0.5 to 4.5 LPM), methanol concentration (0 to 35 %) and voltage (4 to 8 V) were analyzed at three different ultrasonic transducer frequencies (0.3, 1.7 and 2.4 MHz). The results showed that the higher frequency (2.4 MHz) transducer had about 8–10 % higher tendency of H<sub>2</sub> production rate against the other two transducers of frequencies 1.7 MHz and 0.3 MHz, respectively. The process parameters that influenced the H<sub>2</sub> production rate include input voltage, which showed a 14–25 % increase in the H<sub>2</sub> production rate from 4 kV to 7.5 kV, and beyond 7.5 kV, it declined. Similarly, the highest H<sub>2</sub> production rate was observed at the higher methanol concentration of 35 % and feed flow rate of 3.5 LPM. The hydrogen selectivity (HS) and methanol conversion (MCP) also calculated and found both positive and negative impacts as per the variations in influencing parameters. The highest raise in HS and MCP were observed about 30–45 % for input voltage whereas the reduction was about 30–40 % for methanol concentration. The feed flow rate showed mixed response.</div></div>","PeriodicalId":23062,"journal":{"name":"Thermal Science and Engineering Progress","volume":"61 ","pages":"Article 103535"},"PeriodicalIF":5.1,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143703883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Experimental study on the operating performance of a novel flat loop heat pipe with liquid channels under terrestrial and accelerated conditions","authors":"Zhen Fang , Yongqi Xie , Jinpeng Wei , Hongwei Wu , Hongxing Zhang , Guoguang Li","doi":"10.1016/j.tsep.2025.103532","DOIUrl":"10.1016/j.tsep.2025.103532","url":null,"abstract":"<div><div>To address the cooling challenges of future advanced airborne electronic equipment, in this article, a dual compensation chamber stainless steel-ammonia flat loop heat pipe (FLHP) with liquid channels was designed and fabricated. A test rig was set up to evaluate the startup and operating performance under two typical acceleration directions and terrestrial conditions. In the current study, acceleration is defined as direction Ⅰ when it is directed from CC2 to CC1, and as direction Ⅱ is when it oriented from the evaporator to the condenser. Experimental results indicated that: (i) under terrestrial conditions, the FLHP can successfully start at 10 W and quickly reach steady state under varying heat loads (10 ∼ 500 W). (ii) the FLHP successfully started and reached a steady state under 6 <em>g</em> acceleration in both directions, but the time required to reach steady state is longer than that under terrestrial conditions. (iii) the steady-state operating temperature versus heat load shows a “V” shaped curve under both terrestrial and acceleration conditions. The transitions from the variable to the constant conductance model occur at heat loads of 200 W, 400 W, and 300 W for terrestrial condition, acceleration direction Ⅰ, and acceleration direction Ⅱ, respectively. (iv) accelerations in both directions increase the FLHP operating temperature. In direction Ⅰ, acceleration mainly affects the fluid distribution between the CCs, altering heat leakage from the evaporator. In direction II, it primarily increases the flow resistance in the external loop. The findings of this study provide strong support for the thermal management of electronic devices, especially offering broad application prospects in complex and variable airborne acceleration environments.</div></div>","PeriodicalId":23062,"journal":{"name":"Thermal Science and Engineering Progress","volume":"61 ","pages":"Article 103532"},"PeriodicalIF":5.1,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143703885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ali Hassan , Mohammad U.H Joardder , Azharul Karim
{"title":"A CFD integrated drying model for improving drying conditions in industry Scale dryers","authors":"Ali Hassan , Mohammad U.H Joardder , Azharul Karim","doi":"10.1016/j.tsep.2025.103533","DOIUrl":"10.1016/j.tsep.2025.103533","url":null,"abstract":"<div><div>Drying is a complex process involving simultaneous momentum, heat and mass transfer driven by gradients in pressure, temperature, moisture concentration, and velocity. While recent efforts have integrated drying models with computational fluid dynamics (CFD) to improve process understanding, most existing models focus on convective drying of single samples. There remains a critical need for further studies to optimize drying conditions using CFD-integrated models for multiple samples under diverse inlet air velocities. In this study, a CFD-integrated drying model was developed to investigate drying uniformity for multiple samples under various conditions. This includes investigating whether a meshed inlet can enhance airflow distribution, thereby improving both drying uniformity and drying rates. Moreover, the study examined the uniformity of air velocity, moisture content, and sample temperature for different sample arrangements and positions within the drying chamber. Results indicated that higher air velocities significantly enhance moisture removal and temperature uniformity among samples, while sample placement notably affects drying rates. Moreover, the inclusion of meshed inlet can reduce the low energy spots within the drying chamber for optimizing the drying efficiency of the system. However, higher uniformities in air velocity and sample temperature, and moisture content were achieved from the non-perforated air inlet. This research highlights the critical role of meshed inlet and sample orientations in optimizing airflow and drying conditions, providing insights to improve energy efficiency, achieve consistent drying performance, and reduce quality degradation during the drying process.</div></div>","PeriodicalId":23062,"journal":{"name":"Thermal Science and Engineering Progress","volume":"61 ","pages":"Article 103533"},"PeriodicalIF":5.1,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143685952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Injamamul Haque , Naushad Ali , Tabish Alam , Tauseef Uddin Siddiqui , Mushtaq Ahmad Ansari , Jagmohan Yadav , Shivam Srivastava
{"title":"Optimization of semi-pendeloque grooved in micro-channel heat sinks for thermal management under optimal pumping power","authors":"Injamamul Haque , Naushad Ali , Tabish Alam , Tauseef Uddin Siddiqui , Mushtaq Ahmad Ansari , Jagmohan Yadav , Shivam Srivastava","doi":"10.1016/j.tsep.2025.103531","DOIUrl":"10.1016/j.tsep.2025.103531","url":null,"abstract":"<div><div>In the relentless pursuit of efficient thermal management for high-power electronic devices, microchannel heat sinks (MCHS) have emerged as a pivotal solution due to their superior heat dissipation capabilities. This study focuses on optimizing MCHS by incorporating semi-pendeloque grooves on the sidewalls, arranged alternately and designed with varying angles from 10° to 30°. Using numerical technique, the thermal and hydrodynamic performance of these modified MCHSs were quantitatively analyzed. The results reveal that the inclusion of semi-pendeloque grooves significantly enhances the heat transfer rate. At Reynolds number (Re) of 900 and a groove angle of 10°, the Nusselt number increased to 14.17, up from 12.49 at a groove angle of 30°. Additionally, the maximum temperature at the base of the microchannel dropped from 319.82 K at Re = 500 to 313.27 K at Re = 900 with a fixed groove angle of 10°. However, results are also demonstrated that larger groove angle also leads to a marginal higher pressure drop, which means slightly high pumping power is needed. The study suggests that fine-tuning the groove angle and arrangement in microchannel heat sinks can significantly enhance thermal performance, which makes it a promising approach for advanced cooling in electronic devices.</div></div>","PeriodicalId":23062,"journal":{"name":"Thermal Science and Engineering Progress","volume":"61 ","pages":"Article 103531"},"PeriodicalIF":5.1,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143714262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Johannes Losacker, Alex M. Garcia, Nico Schmitz, Christian Wuppermann
{"title":"Full-spectrum k-distribution weighted sum of gray gases model for air and oxyfuel combustion of hydrogen-hydrocarbon blends at atmospheric pressure","authors":"Johannes Losacker, Alex M. Garcia, Nico Schmitz, Christian Wuppermann","doi":"10.1016/j.tsep.2025.103514","DOIUrl":"10.1016/j.tsep.2025.103514","url":null,"abstract":"<div><div>In the context of decarbonization of heating processes, alternative fuels as hydrogen, ammonia, or biogas are explored to substitute conventional fuels as natural gas. The altered flue gas compositions from such flames demand flexible modeling of radiative properties of the participating gases H<sub>2</sub>O and CO<sub>2</sub>. Various Weighted Sum of Gray Gases (WSGG) model formulations and coefficients have been proposed in the literature, but few cover all conditions that result from the combustion of any blend of the aforementioned fuels. In this work, two sets of coefficients for a WSGG model with 5 gray gases are calibrated for air and oxyfuel combustion conditions at atmospheric pressure, to improve on the accuracy and flexibility of existing models. Weights and absorption coefficients are derived from <em>k</em>-distributions based on line-by-line integrations using the HITEMP 2010 spectroscopic database. Base functions are fitted to continuously recover the weights and absorption coefficients within the range of calibration. The new model covers H<sub>2</sub>O to CO<sub>2</sub> molar ratios of <span><math><mrow><mn>1</mn><mo>≤</mo><mi>M</mi><mi>r</mi><mo>≤</mo><mi>∞</mi></mrow></math></span>, and temperatures in the range of <span><math><mrow><mn>300</mn><mspace></mspace><mi>K</mi><mo>≤</mo><mi>T</mi><mo>≤</mo><mn>2700</mn><mspace></mspace><mi>K</mi></mrow></math></span> for air combustion, and <span><math><mrow><mn>300</mn><mspace></mspace><mi>K</mi><mo>≤</mo><mi>T</mi><mo>≤</mo><mn>3000</mn><mspace></mspace><mi>K</mi></mrow></math></span> for oxyfuel combustion. The models are assessed by predictions of total emissivity as well as radiative heat flux and source term in a 1D slab. Benchmark solutions are obtained from line-by-line integrations covering the compositions of the calibration database. The new model shows significantly improved predictions in comparison to recent WSGG models.</div></div>","PeriodicalId":23062,"journal":{"name":"Thermal Science and Engineering Progress","volume":"61 ","pages":"Article 103514"},"PeriodicalIF":5.1,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143685886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Thermodynamic analysis of a sustainable solar-biomass hybrid dryer with thermal energy storage systems","authors":"Dhananjay Kumar , Pavitra Singh , Pankaj Kalita , Pinakeswar Mahanta","doi":"10.1016/j.tsep.2025.103527","DOIUrl":"10.1016/j.tsep.2025.103527","url":null,"abstract":"<div><div>An efficient continuous-type solar-biomass powered grain-dryer coupled with thermal storage mediums (sensible and latent) has been developed for small-scale farmers. Thermodynamic analysis of the developed dryer has been performed for performance optimization. This investigation comprises the energy and exergy examination of paddy drying of 12 kg capacity for the moisture content reduction of 20.4 % (34.2 % to 13.8 %). Thermal storage mediums, such as pebbles and paraffin wax, are used to maintain stable temperature during the drying process in the chamber of a biomass-based dryer. In this analysis, two batches of paddy (12 kg/batch) were successfully dried in each drying mode (solar and biomass operating mode). Solar energy was used in paddy drying during the daytime and biomass energy during the night. The improvement potential and sustainability index of dryer under solar drying have also been evaluated. The environmental impact analysis of the dryer has also been conducted.</div></div>","PeriodicalId":23062,"journal":{"name":"Thermal Science and Engineering Progress","volume":"61 ","pages":"Article 103527"},"PeriodicalIF":5.1,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}