Applied Thermal Engineering最新文献

Waste heat utilization of low-temperature proton exchange membrane fuel cell refrigerated vehicle with integrated absorption-compression refrigeration system

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2025-02-28 DOI: 10.1016/j.applthermaleng.2025.126103

Yufan Yang , Chunhuan Luo , Chunting Zhou , Muran He

To enhance the performance of low-temperature proton exchange membrane fuel cells (LT-PEMFC) and meet cooling demands, this study proposes an absorption-compression cycle using R1336mzz(Z)/TEGDME as the working pair, coupled with LT-PEMFC. The thermal properties of this working pair, including saturation vapor pressure and specific heat capacity, were measured and regressed, while the mixing enthalpy and specific enthalpy were calculated using the NRTL model. Based on the obtained thermal properties, MATLAB simulations were performed to evaluate the performance of the coupled system under varying operating conditions representative of both winter and summer environments. The results indicate that this coupled system can effectively utilize the low-temperature waste heat generated by LT-PEMFC to provide cooling at −20 °C. When LT-PEMFC produces 60 kW of usable electric power, the cooling capacity can reach 32.5 kW in winter and 60.1 kW in summer. Under typical winter and summer operating conditions, the coefficient of performance of the coupled system is approximately 0.73, representing a 9 % improvement over the compression cycle and a 65.5 % increase compared to the standalone LT-PEMFC, which is significant for enhancing vehicle performance.

{"title":"Waste heat utilization of low-temperature proton exchange membrane fuel cell refrigerated vehicle with integrated absorption-compression refrigeration system","authors":"Yufan Yang , Chunhuan Luo , Chunting Zhou , Muran He","doi":"10.1016/j.applthermaleng.2025.126103","DOIUrl":"10.1016/j.applthermaleng.2025.126103","url":null,"abstract":"<div><div>To enhance the performance of low-temperature proton exchange membrane fuel cells (LT-PEMFC) and meet cooling demands, this study proposes an absorption-compression cycle using R1336mzz(Z)/TEGDME as the working pair, coupled with LT-PEMFC. The thermal properties of this working pair, including saturation vapor pressure and specific heat capacity, were measured and regressed, while the mixing enthalpy and specific enthalpy were calculated using the NRTL model. Based on the obtained thermal properties, MATLAB simulations were performed to evaluate the performance of the coupled system under varying operating conditions representative of both winter and summer environments. The results indicate that this coupled system can effectively utilize the low-temperature waste heat generated by LT-PEMFC to provide cooling at −20 °C. When LT-PEMFC produces 60 kW of usable electric power, the cooling capacity can reach 32.5 kW in winter and 60.1 kW in summer. Under typical winter and summer operating conditions, the coefficient of performance of the coupled system is approximately 0.73, representing a 9 % improvement over the compression cycle and a 65.5 % increase compared to the standalone LT-PEMFC, which is significant for enhancing vehicle performance.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"269 ","pages":"Article 126103"},"PeriodicalIF":6.1,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Time series analysis of field data for soft faults detection and degradation assessment in residential air conditioning systems

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2025-02-28 DOI: 10.1016/j.applthermaleng.2025.126104

Belén Llopis-Mengual , David P. Yuill , Emilio Navarro-Peris

Residential Air Conditioning units are significant contributors to energy consumption. Soft faults in these units, such as refrigerant leakage and inadequate condenser airflow, can lead to reduced equipment life, decreased cooling capacity, and increased energy consumption. While extensive research has been conducted on Fault Detection and Diagnosis (FDD) in AC systems, most studies rely on laboratory-imposed faults or simulations, which may not reflect real-world conditions. Thus, long-term field data analyses remain scarce. This study develops and validates a time-series analysis-based methodology for detecting and diagnosing these faults in residential air conditioning units. Virtual refrigerant charge is used to detect refrigerant leakage, while the difference between condensing and ambient temperatures is used to detect inadequate condenser airflow. The methodology is tested on a dataset of 81 units across the US and Canada, monitored over a full cooling season (2–7 months). Results show that 2 units exhibited degraded condenser airflow and 5 had refrigerant leakage. Refrigerant leakage resulted in a monthly Coefficient of Performance (COP) reduction of 4–10% and an increase in daily energy consumption by 4–26% over a faulty period of 6.5 to 15 weeks. Similarly, units with degraded condenser airflow experienced a COP reduction of 4–7% per month, and daily electricity consumption increased by 15–17% over a faulty period of 8–8.5 weeks. This study quantifies fault performance degradation under residential conditions by analyzing real-world operational data, offering a field-tested approach for identifying and assessing soft faults. This work highlights the importance of timely fault detection and maintenance in residential Air Conditioning units to ensure efficiency, minimize energy waste, and prevent system damage.

{"title":"Time series analysis of field data for soft faults detection and degradation assessment in residential air conditioning systems","authors":"Belén Llopis-Mengual , David P. Yuill , Emilio Navarro-Peris","doi":"10.1016/j.applthermaleng.2025.126104","DOIUrl":"10.1016/j.applthermaleng.2025.126104","url":null,"abstract":"<div><div>Residential Air Conditioning units are significant contributors to energy consumption. Soft faults in these units, such as refrigerant leakage and inadequate condenser airflow, can lead to reduced equipment life, decreased cooling capacity, and increased energy consumption. While extensive research has been conducted on Fault Detection and Diagnosis (FDD) in AC systems, most studies rely on laboratory-imposed faults or simulations, which may not reflect real-world conditions. Thus, long-term field data analyses remain scarce. This study develops and validates a time-series analysis-based methodology for detecting and diagnosing these faults in residential air conditioning units. Virtual refrigerant charge is used to detect refrigerant leakage, while the difference between condensing and ambient temperatures is used to detect inadequate condenser airflow. The methodology is tested on a dataset of 81 units across the US and Canada, monitored over a full cooling season (2–7 months). Results show that 2 units exhibited degraded condenser airflow and 5 had refrigerant leakage. Refrigerant leakage resulted in a monthly Coefficient of Performance (COP) reduction of 4–10% and an increase in daily energy consumption by 4–26% over a faulty period of 6.5 to 15 weeks. Similarly, units with degraded condenser airflow experienced a COP reduction of 4–7% per month, and daily electricity consumption increased by 15–17% over a faulty period of 8–8.5 weeks. This study quantifies fault performance degradation under residential conditions by analyzing real-world operational data, offering a field-tested approach for identifying and assessing soft faults. This work highlights the importance of timely fault detection and maintenance in residential Air Conditioning units to ensure efficiency, minimize energy waste, and prevent system damage.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"269 ","pages":"Article 126104"},"PeriodicalIF":6.1,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Local heat transfer measurement in a volumetrically heated TPMS lattice using distributed optical fiber thermal sensing

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2025-02-28 DOI: 10.1016/j.applthermaleng.2025.126101

Brett Prussack , Ian Jentz , Tiago A. Moreira , Erik Pagenkopf , Nicolas Woolstenhulme , Greg Nellis , Mark Anderson

As additive manufacturing continues to reduce design constraints on heat exchange geometries, methods for high-fidelity local heat transfer measurements in nonconventional channel geometries are critical to their continued development. This study presents a novel method for measuring local heat transfer performance in volumetrically heated lattices using a distributed optical fiber temperature sensor. A diamond-type triply periodic minimal surface (TPMS) lattice, 3D-printed from a conductive polymer, was Joule heated while it was convectively cooled with air. Temperature measurements were taken at the solid–fluid interface across 14 internal locations using a single optical fiber over the Reynolds number range 800–2750. The TPMS lattice achieved up to 312% higher heat transfer coefficients compared to developing flow in a straight tube. A Nusselt number correlation was developed for the diamond TPMS, which showed good agreement with data collected for comparable geometries available in literature. This study presents a robust and new method for experimental measurement of the heat transfer coefficient in complex geometries and helps to understand and quantify the exceptional performance of TPMS heat transfer geometries.

{"title":"Local heat transfer measurement in a volumetrically heated TPMS lattice using distributed optical fiber thermal sensing","authors":"Brett Prussack , Ian Jentz , Tiago A. Moreira , Erik Pagenkopf , Nicolas Woolstenhulme , Greg Nellis , Mark Anderson","doi":"10.1016/j.applthermaleng.2025.126101","DOIUrl":"10.1016/j.applthermaleng.2025.126101","url":null,"abstract":"<div><div>As additive manufacturing continues to reduce design constraints on heat exchange geometries, methods for high-fidelity local heat transfer measurements in nonconventional channel geometries are critical to their continued development. This study presents a novel method for measuring local heat transfer performance in volumetrically heated lattices using a distributed optical fiber temperature sensor. A diamond-type triply periodic minimal surface (TPMS) lattice, 3D-printed from a conductive polymer, was Joule heated while it was convectively cooled with air. Temperature measurements were taken at the solid–fluid interface across 14 internal locations using a single optical fiber over the Reynolds number range 800–2750. The TPMS lattice achieved up to 312% higher heat transfer coefficients compared to developing flow in a straight tube. A Nusselt number correlation was developed for the diamond TPMS, which showed good agreement with data collected for comparable geometries available in literature. This study presents a robust and new method for experimental measurement of the heat transfer coefficient in complex geometries and helps to understand and quantify the exceptional performance of TPMS heat transfer geometries.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"269 ","pages":"Article 126101"},"PeriodicalIF":6.1,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Analytical model for characterizing mass transfer of volatile organic compounds in internally-cooled liquid desiccant dehumidifiers

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2025-02-28 DOI: 10.1016/j.applthermaleng.2025.126109

Zhihang Liu, Huangxi Fu, Shunyi Huang

Volatile organic compounds (VOCs) in indoor air pose a significant hazard to human health, owing to their potential associated chronic and acute health risks. Liquid dehumidification has emerged as a promising technology for eliminating indoor VOCs. However, the studies on the mass transfer behavior of VOCs in dehumidifiers are mainly confined to experimental and numerical methods, which are both time-consuming and labor-intensive. In contrast, analytical methods are more attractive and advantageous in solving these problems. Therefore, in the present study, we propose an analytical model to quantify the mass transfer behavior of VOCs in an internally-cooled dehumidifier. To confirm the broad applicability of the proposed model, both the hydrophilic and hydrophobic properties of VOCs were considered. Formaldehyde and benzene were selected as two typical representatives. The reliability of the proposed model was demonstrated by investigating the VOC transfer characteristics and removal performance as the key factors varied. It was found that the analytical results agree well with the published numerical results. With variation of the key parameters, the trends of the VOC removal performance obtained by the analytical and numerical methods are basically in agreement. The analytical model can not only effectively describe the mass transfer characteristics of VOCs, but also adequately determine the VOCs removal performance. Moreover, the analytical model shows a wide-range response to different VOCs, with the order of Henry’s law constant ranging from 10⁻⁵ to 10⁻³. For both hydrophilic formaldehyde and hydrophobic benzene, the deviations do not exceed ± 10 %. This study provides an intuitive and labor-saving method to evaluate VOC removal using internally-cooled dehumidifiers.

{"title":"Analytical model for characterizing mass transfer of volatile organic compounds in internally-cooled liquid desiccant dehumidifiers","authors":"Zhihang Liu, Huangxi Fu, Shunyi Huang","doi":"10.1016/j.applthermaleng.2025.126109","DOIUrl":"10.1016/j.applthermaleng.2025.126109","url":null,"abstract":"<div><div>Volatile organic compounds (VOCs) in indoor air pose a significant hazard to human health, owing to their potential associated chronic and acute health risks. Liquid dehumidification has emerged as a promising technology for eliminating indoor VOCs. However, the studies on the mass transfer behavior of VOCs in dehumidifiers are mainly confined to experimental and numerical methods, which are both time-consuming and labor-intensive. In contrast, analytical methods are more attractive and advantageous in solving these problems. Therefore, in the present study, we propose an analytical model to quantify the mass transfer behavior of VOCs in an internally-cooled dehumidifier. To confirm the broad applicability of the proposed model, both the hydrophilic and hydrophobic properties of VOCs were considered. Formaldehyde and benzene were selected as two typical representatives. The reliability of the proposed model was demonstrated by investigating the VOC transfer characteristics and removal performance as the key factors varied. It was found that the analytical results agree well with the published numerical results. With variation of the key parameters, the trends of the VOC removal performance obtained by the analytical and numerical methods are basically in agreement. The analytical model can not only effectively describe the mass transfer characteristics of VOCs, but also adequately determine the VOCs removal performance. Moreover, the analytical model shows a wide-range response to different VOCs, with the order of Henry’s law constant ranging from 10<sup>−5</sup> to 10<sup>−3</sup>. For both hydrophilic formaldehyde and hydrophobic benzene, the deviations do not exceed ± 10 %. This study provides an intuitive and labor-saving method to evaluate VOC removal using internally-cooled dehumidifiers.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"269 ","pages":"Article 126109"},"PeriodicalIF":6.1,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Performance study of ultra-low temperature district heating system based on double-loop booster heat pump control strategy

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2025-02-27 DOI: 10.1016/j.applthermaleng.2025.126084

Yuexuan Gong, Guoyuan Ma, Yu Song, Lei Wang, Junrui Nie, Lu Wang

In recent years, the ultra-low-temperature district heating (ULTDH) systems has been developed to further reduce the heat loss in the district heating network. In this paper, on the basis of the ULTDH system, a double-loop booster heat pump (DLBHP) system used for terminal heating is proposed to improve the uniformity of temperature difference and heat transfer efficiency. The building heat load in Beijing was simulated using DEST software, and then the heating simulation model of the DLBHP was established through the TRNSYS software simulation platform. By changing the various control strategies on the heat source side and the heat sink side, the optimization of the operation and control strategies and the system performance were analyzed. The simulation results indicate that compared with the traditional operation modes, the system average COP with optimized control strategy can be increased by up to 9.24 %, and the power saving during the heating season can be up to 1389 kW·h. It can satisfy the real-time heat load demand of users, and has a large energy-saving potential as well as a broad market application prospect.

{"title":"Performance study of ultra-low temperature district heating system based on double-loop booster heat pump control strategy","authors":"Yuexuan Gong, Guoyuan Ma, Yu Song, Lei Wang, Junrui Nie, Lu Wang","doi":"10.1016/j.applthermaleng.2025.126084","DOIUrl":"10.1016/j.applthermaleng.2025.126084","url":null,"abstract":"<div><div>In recent years, the ultra-low-temperature district heating (ULTDH) systems has been developed to further reduce the heat loss in the district heating network. In this paper, on the basis of the ULTDH system, a double-loop booster heat pump (DLBHP) system used for terminal heating is proposed to improve the uniformity of temperature difference and heat transfer efficiency. The building heat load in Beijing was simulated using DEST software, and then the heating simulation model of the DLBHP was established through the TRNSYS software simulation platform. By changing the various control strategies on the heat source side and the heat sink side, the optimization of the operation and control strategies and the system performance were analyzed. The simulation results indicate that compared with the traditional operation modes, the system average COP with optimized control strategy can be increased by up to 9.24 %, and the power saving during the heating season can be up to 1389 kW·h. It can satisfy the real-time heat load demand of users, and has a large energy-saving potential as well as a broad market application prospect.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"269 ","pages":"Article 126084"},"PeriodicalIF":6.1,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143520329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Modeling thermal inertia effects using the thermal resistance network approach on a small-scale high-temperature ORC system

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2025-02-27 DOI: 10.1016/j.applthermaleng.2025.126018

Radheesh Dhanasegaran, Antti Uusitalo, Juha Honkatukia, Teemu Turunen-Saaresti

Organic Rankine Cycle technology is an effective way to convert low to medium-grade waste heat into electricity. Understanding the dynamic behavior of Organic Rankine Cycle systems is vital because they often operate under fluctuating operating conditions. Consequently, dynamic simulations are essential for system design and optimization; they can also predict real-time operational behavior and ensure system safety. This study used a thermal resistance network modeling method to simulate the dynamic behavior of heat exchangers in a high-temperature micro-organic Rankine cycle. The focus was on the transient effects caused by wall thermal inertia. The study examined three transient simulations in detail and validated their results against experimental data. The thermal resistance network method accurately predicted the cycle’s transient effects, offering a straightforward predictive tool for transient operations in waste heat recovery systems. Moreover, the study emphasized the critical impact of non-condensable gases on condenser performance, especially in systems with low condensing pressures.

{"title":"Modeling thermal inertia effects using the thermal resistance network approach on a small-scale high-temperature ORC system","authors":"Radheesh Dhanasegaran, Antti Uusitalo, Juha Honkatukia, Teemu Turunen-Saaresti","doi":"10.1016/j.applthermaleng.2025.126018","DOIUrl":"10.1016/j.applthermaleng.2025.126018","url":null,"abstract":"<div><div>Organic Rankine Cycle technology is an effective way to convert low to medium-grade waste heat into electricity. Understanding the dynamic behavior of Organic Rankine Cycle systems is vital because they often operate under fluctuating operating conditions. Consequently, dynamic simulations are essential for system design and optimization; they can also predict real-time operational behavior and ensure system safety. This study used a thermal resistance network modeling method to simulate the dynamic behavior of heat exchangers in a high-temperature micro-organic Rankine cycle. The focus was on the transient effects caused by wall thermal inertia. The study examined three transient simulations in detail and validated their results against experimental data. The thermal resistance network method accurately predicted the cycle’s transient effects, offering a straightforward predictive tool for transient operations in waste heat recovery systems. Moreover, the study emphasized the critical impact of non-condensable gases on condenser performance, especially in systems with low condensing pressures.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"269 ","pages":"Article 126018"},"PeriodicalIF":6.1,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Thermoelectric cooling systems for eVTOL batteries operating on hot days

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2025-02-27 DOI: 10.1016/j.applthermaleng.2025.125999

Chunrong Zhao , Seeta Ratnam Gunti , Hagen Kellermann , Andrew Gong , Simon Coburn , Andrew Moore , Dries Verstraete

Fast advancements in high-energy and -power density batteries, have recently enabled fully battery-powered advanced air mobility (AAM) aircraft development. Given the thermal-sensitive characteristics of lithium-ion batteries (LiB), those electric aircraft require a lightweight and highly-efficient battery thermal management system (BTMS) to dissipate waste heat, particularly for power-hungry flight phases or at high ambient temperature. To date, the relevant investigations, specifically for electric aircraft, are missing; therefore, as the first attempt, we introduce a thermoelectric heat exchanger into a previously developed liquid-cooling-based BTMS for a tilt-wing electric vertical take-off and landing (eVTOL) aircraft to mitigate aforementioned aerothermal concerns. We first compare a BTMS with and without the thermoelectric cooler (TEC) based on a hover-free flight mission to demonstrate its effectiveness and weight-and-power penalty. We then simulate and compare BTMS performance for four different hover durations (1, 3, 5, and 7 min). Our results show that, as the hover duration increases, the TEC-based BTMS works well for ambient temperature up to 45 °C at the expense of a reduced number of flights and additional weight. On the contrary, a TEC-free BTMS can only manage battery temperatures and health for ambient temperatures below 20 °C.

{"title":"Thermoelectric cooling systems for eVTOL batteries operating on hot days","authors":"Chunrong Zhao , Seeta Ratnam Gunti , Hagen Kellermann , Andrew Gong , Simon Coburn , Andrew Moore , Dries Verstraete","doi":"10.1016/j.applthermaleng.2025.125999","DOIUrl":"10.1016/j.applthermaleng.2025.125999","url":null,"abstract":"<div><div>Fast advancements in high-energy and -power density batteries, have recently enabled fully battery-powered advanced air mobility (AAM) aircraft development. Given the thermal-sensitive characteristics of lithium-ion batteries (LiB), those electric aircraft require a lightweight and highly-efficient battery thermal management system (BTMS) to dissipate waste heat, particularly for power-hungry flight phases or at high ambient temperature. To date, the relevant investigations, specifically for electric aircraft, are missing; therefore, as the first attempt, we introduce a thermoelectric heat exchanger into a previously developed liquid-cooling-based BTMS for a tilt-wing electric vertical take-off and landing (eVTOL) aircraft to mitigate aforementioned aerothermal concerns. We first compare a BTMS with and without the thermoelectric cooler (TEC) based on a hover-free flight mission to demonstrate its effectiveness and weight-and-power penalty. We then simulate and compare BTMS performance for four different hover durations (1, 3, 5, and 7 min). Our results show that, as the hover duration increases, the TEC-based BTMS works well for ambient temperature up to 45 °C at the expense of a reduced number of flights and additional weight. On the contrary, a TEC-free BTMS can only manage battery temperatures and health for ambient temperatures below 20 °C.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"269 ","pages":"Article 125999"},"PeriodicalIF":6.1,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143511273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Generalized engineering equations of heat-transfer performance for twisted heat exchanger with slurries from biogas plants by using Machine learning driven by mechanism and data

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2025-02-26 DOI: 10.1016/j.applthermaleng.2025.126046

Yan Liu , Shanshan Wang , Liwen Mu , Mikael Risberg , Urban Jansson , Jiahua Zhu , Xiaohua Lu , Xiaoyan Ji , Jingjing Chen

The development of generalized engineering equations of the heat-transfer performance in enhanced geometries for different slurries is crucial for practical applications but difficult owing to the complex rheological properties. In the present study, a method of computational-fluid-dynamics-data-driven machine learning was proposed to establish generalized engineering equations in a novel twisted geometry for multiple slurries with a single substrate. The applicability of the equations for a mixed slurry was determined by comparing the predictions and computational fluid dynamics simulations. It was found that the established equations considering the key parameter–effective shear rate show a high accuracy with an average relative deviation of 17.3 % for single-substrate slurries with the scope of viscosities and flow behavior index ranging from 0.057-93.96 Pa·s and 0.257–0.579, respectively. Moreover, the generalized engineering equations show an average relative deviation of 12.4 % in prediction for the mixed slurry possessing the temperature- and shearing-sensitive rheological behavior. The generalized engineering equations quantitatively reveal the positive effect of non-Newtonian behavior on the heat-transfer enhancement of THT for different slurries. Based on this mechanism, a mixed slurry is recommend with energy-conservation of 60.00 GW·h/year for a full-scale biogas plant.

{"title":"Generalized engineering equations of heat-transfer performance for twisted heat exchanger with slurries from biogas plants by using Machine learning driven by mechanism and data","authors":"Yan Liu , Shanshan Wang , Liwen Mu , Mikael Risberg , Urban Jansson , Jiahua Zhu , Xiaohua Lu , Xiaoyan Ji , Jingjing Chen","doi":"10.1016/j.applthermaleng.2025.126046","DOIUrl":"10.1016/j.applthermaleng.2025.126046","url":null,"abstract":"<div><div>The development of generalized engineering equations of the heat-transfer performance in enhanced geometries for different slurries is crucial for practical applications but difficult owing to the complex rheological properties. In the present study, a method of computational-fluid-dynamics-data-driven machine learning was proposed to establish generalized engineering equations in a novel twisted geometry for multiple slurries with a single substrate. The applicability of the equations for a mixed slurry was determined by comparing the predictions and computational fluid dynamics simulations. It was found that the established equations considering the key parameter–effective shear rate show a high accuracy with an average relative deviation of 17.3 % for single-substrate slurries with the scope of viscosities and flow behavior index ranging from 0.057-93.96 Pa·s and 0.257–0.579, respectively. Moreover, the generalized engineering equations show an average relative deviation of 12.4 % in prediction for the mixed slurry possessing the temperature- and shearing-sensitive rheological behavior. The generalized engineering equations quantitatively reveal the positive effect of non-Newtonian behavior on the heat-transfer enhancement of THT for different slurries. Based on this mechanism, a mixed slurry is recommend with energy-conservation of 60.00 GW·h/year for a full-scale biogas plant.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"269 ","pages":"Article 126046"},"PeriodicalIF":6.1,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Modeling and optimization of an endoreversible non-isothermal chemical pump cycle via Onsager equations

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2025-02-26 DOI: 10.1016/j.applthermaleng.2025.126089

Shuangshuang Shi, Lingen Chen, Yanlin Ge, Huijun Feng

Assuming that the heat-and-mass-transfer process obeys the Onsager equations in linear irreversible thermodynamics, a model for an endoreversible non-isothermal-chemical-pump cycle is built, and its performance is optimized. The analytical results of rate of energy-pumping and vector coefficient of performances (See Eq. (20) in this paper for its definition) are obtained. Effects of cycle design parameters on the cycle optimal performances are analyzed. The findings show that: With the increase of energy flux, the rate of energy-pumping increases, and vector coefficient of performances decrease. With the increase of mass-transfer flux, the rate of energy-pumping is unchanged. The surfaces of rate of energy-pumping versus vector coefficient of performances are monotonically decreasing ones, and with increase of cross-phenomenological coefficient of heat-and-mass-transfer, the vector coefficient of performances increase. Research results involve two special cases: the optimal performance for an endoreversible Carnot heat-pump cycle with linear phenomenological heat-transfer law and the optimal performance for an endoreversible isothermal chemical pump with linear mass-transfer law.

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引用次数: 0

Optimizing a ternary hybrid ferrofluid slip flow with magnetic dipole and viscous dissipation by Response Surface Methodology (RSM)

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2025-02-26 DOI: 10.1016/j.applthermaleng.2025.126087

Shahirah Abu Bakar , Ioan Pop , Lit Ken Tan , Norihan Md Arifin

In electromagnetism, a magnetic dipole is a tiny loop of electric current or a pair of magnetic poles. As the loop size decreases to zero while maintaining a constant magnetic moment, it forms a magnetic dipole. Composed by the magnetic particles, ferromagnetic fluids align with magnetic fields and when a magnetic dipole interacts with such fluids, the particles magnetize the fluid and influence the dipole’s field. Hence, this study investigates the magnetic dipole and velocity slip on ternary hybrid ferrofluid flow past a shrinking surface. The model considers three magnetic nanoparticles – iron oxide (Fe₃O₄), cobalt ferrite (CoFe₂O₄), and copper (Cu) – dispersed in a base fluid. The similarity transformation technique is applied to derive mathematical models, which were solved numerically using bvp4c program in MATLAB. The analysis reveals that ferrohydrodynamic interaction reduces the skin friction coefficient and heat transfer rate but enhances velocity and temperature profiles. Additionally, the ternary hybrid ferrofluid is also shown to outperform both conventional ferrofluid and hybrid ferrofluid in fluid flow characteristics. Response Surface Methodology (RSM) is employed to identify the optimal combination of parameters, suggesting that the highest ferrohydrodynamic parameter and viscous dissipation, along with minimal Cu-nanoparticle concentration, maximize the heat transfer rate. Contour and surface plots illustrate these optimal conditions. This study highlights an innovative application of ternary ferrofluid with a magnetic dipole and employs RSM to optimize parameters for enhanced heat transfer performance, addressing a gap in existing literature and providing the way for further advancements in this field.

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引用次数: 0