Applied Thermal Engineering最新文献

{"title":"Experimental study of a novel guided sequential immersion cooling system for battery thermal management","authors":"","doi":"10.1016/j.applthermaleng.2024.124337","DOIUrl":"10.1016/j.applthermaleng.2024.124337","url":null,"abstract":"<div><p>Immersion cooling exhibits superior cooling performance compared to traditional battery thermal management systems (BTMS). However, a significant challenge of immersion cooling is the spatial variation of temperature within both the coolant and lithium-ion batteries (LIBs). This research proposes a guided sequential immersion cooling (GSIC) BTMS to address this issue. Experimental studies were conducted to evaluate the heat dissipation performance of the GSIC structure under various conditions, including extreme loads. The results indicate that under the static flow immersion cooling (SFIC) scheme, cooling the tabs significantly influences the overall performance. Immersing the tabs can reduce the maximum battery temperature by 10.403 °C, although the spatial variation of temperature persists. Under forced flow immersion cooling (FFIC) conditions, increasing the coolant flow rate dissipates the heat generated by LIBs more effectively. Even at an extreme discharge rate of 5C, the maximum temperature remains below 45 °C. The average temperature reduction at the tabs is greater than the battery body, and with increased flow rates, the temperature difference between the two can be maintained within 1 °C under all conditions. As the flow rate keeps increasing, the average temperature at the tabs gets even lower than the battery body at low loads. This demonstrates that the GSIC BTMS can suppress the temperature rise at the tabs, which is a critical heat risk. Moreover, the temperature uniformity of the LIBs module is improved. As the flow rate increases, the temperature difference within the LIBs module decreases when the discharge rates is between 1C and 5C. Theoretical analysis confirms that increasing flow rates for low loads can suppress temperature rise, albeit with increased power consumption and reduced cooling efficiency. High flow rates are more suitable for high load conditions of the LIBs. These results validate the feasibility of the GSIC BTMS and provide new insights for the development of immersion cooling BTMS.</p></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142229394","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}

{"title":"Impact of cylinder deactivation on fuel efficiency in off-road heavy-duty diesel engines during high engine speed operation","authors":"","doi":"10.1016/j.applthermaleng.2024.124333","DOIUrl":"10.1016/j.applthermaleng.2024.124333","url":null,"abstract":"<div><p>Off-road heavy-duty diesel engines are equipped with complex aftertreatment systems to meet the stringent EPA Tier 4 emission standards. Traditionally, the thermal management of the aftertreatment system, aimed at efficiently reducing tailpipe emissions, involves controlling engine exhaust flow and temperature. However, this approach often leads to inefficient engine operation, especially in the low to mid-load regions, resulting in higher fuel consumption. Prior studies have highlighted the potential of cylinder deactivation (CDA) in reducing fuel consumption and increasing the exhaust temperature for thermal management in on-road applications. As the significance of controlling greenhouse gas (GHG) emissions from off-road machinery comes into focus, this study aims to experimentally demonstrate the fuel efficiency benefits and efficient aftertreatment thermal management achieved through CDA during high-speed operation on a Tier 4 level off-road heavy-duty diesel engine. In a typical off-road duty cycle, such as Non-Road Transient Cycle (NRTC), about 82.5% of cycle’s energy is produced in the engine speed range of 1750–2200 rpm, prompting investigation into the impact of CDA during high-speed operations. CDA results in airflow reductions and increased exhaust gas temperatures due to lower air–fuel ratio (AFR). The reduced airflow operation minimizes pumping work, allowing for higher open cycle efficiency, and thereby translating into lower fuel consumption. The study reveals a new finding: fuel benefits from CDA extend over a larger load range (up to 8.3 bar BMEP) during high-speed operation in off-road heavy-duty engines compared to findings in on-road heavy-duty engines. This phenomenon can be attributed to sufficient oxygen inducted during CDA operation, resulting from similar turbocharger speeds compared to all-cylinder firing operation, especially at high-loads, thereby maintaining particulate matter (PM) concentration within prescribed constraints. Steady-state test results demonstrate a reduction in fuel consumption from 33.7% at 0.4 bar to 1.4% at 8.3 bar BMEP, at 2100 rpm engine speed.</p></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142229398","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}

{"title":"Numerical study on comprehensive performances of pipe-embedded building envelope integrated with arc-finned heat charging system","authors":"","doi":"10.1016/j.applthermaleng.2024.124362","DOIUrl":"10.1016/j.applthermaleng.2024.124362","url":null,"abstract":"<div><p>In the context of accelerating toward carbon neutrality, building envelopes are gradually regarded as multifunctional units with structural and energy attributes. To address the capacity mismatch between heat injection and thermal diffusion processes that hinder performance improvement of pipe-embedded energy walls, the arc-finned pipe-embedded energy walls (i.e., Arc-finPEWs) with directional heat-charging capacity are put forward. Subsequently, a validated mathematical model is established to explore the transient thermal behaviors of Arc-finPEWs as well as the impacts of 7 key parameters on its energy-saving potentials. Results showed that the directional heat-charging measures could improve the heat-charging capacity in specified directions, and the enhancement effect was more obvious as pipe spacing increased. Besides, the fin number (FN), shank length (SL), and fin angle (FA) were the top three influencing parameters in auxiliary-heating mode, whereas impacts of FA, FN, and arc angle (AA) ranked the top three in load-reduction mode. Furthermore, a larger FN and SL contributed to reducing total primary energy consumption and creating more robust invisible thermal barriers in auxiliary-heating mode, while left-facing fins or SL settings that are too high or too low were unfavorable in load-reduction mode. Meanwhile, the arc-fin designs with SL=0.6, FA=150° and AA=30° in auxiliary-heating mode and FA=30°, SL≤0.4 and AA≤15° in load-reduction mode are suggested. Compared to conventional energy-saving walls, the proposed arc-finned heat-charging system could reduce physical thermal insulation material usage with high embodied carbon features by over 60 %.</p></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167239","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}

{"title":"Performance study of the rapid heating drying system based on the reverse Brayton air cycle for agricultural application","authors":"","doi":"10.1016/j.applthermaleng.2024.124363","DOIUrl":"10.1016/j.applthermaleng.2024.124363","url":null,"abstract":"<div><p>Air temperature and humidity control are important for crop storage. Current drying methods in agriculture include solar heating and air source heat pumps, whereas solar heating may lead to poor quality of the dried product and air source heat pumps may not reach the desired temperature when the environment is harsh. In this paper, a rapid heating and drying system based on reverse Brayton air circulation is proposed to obtain high temperature and low humidity air quickly by adjusting the pressure ratio to achieve an adjustable crop drying process. An improved rapid heating and drying system with a water cooler is also proposed to increase the drying efficiency of the system. The results show that the total dehumidification rate of the improved system can reach 11.51 g/s, which is 1.48 g/s higher than that of the rapid heating and drying system without a water cooler, and the dehumidification energy efficiency of the improved system can reach 1.26 kg/(kW^.h), which is 0.11 kg/(kW^.h) higher than that of the rapid heating and drying system without a water-cooling device.</p></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167236","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}

{"title":"Thermal analysis and optimization of data center building envelope insulation in different climate zones","authors":"","doi":"10.1016/j.applthermaleng.2024.124366","DOIUrl":"10.1016/j.applthermaleng.2024.124366","url":null,"abstract":"<div><p>The discrepancy in occupancy between ordinary buildings and data centers requires a unique methodology to achieve more effective cooling load reduction. This paper proposes using net heat flow through the building envelope as a control metric, considering the unique requirements of data centers. A corresponding optimization approach is developed to adjust the insulation thickness accordingly. Using the proposed method, five representative cities from different climate zones are analyzed and compared with the current standards. The orientation of roof insulation design for data centers should be contrary to that of ordinary buildings in all five climate zones. In addition to regions with extremely cold and cold climates, the insulation design orientation of the walls surrounding the data center should also be opposite that of ordinary buildings. Lower cooling load is observed at least 50% of time in a year when using the proposed method among climate zones. This article provides an alternative to using natural cooling sources through a building envelope designed specifically for data centers that have greater climate adaptability.</p></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167238","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}

{"title":"Numerical method research and characteristics analysis on frozen start-up process of high-temperature heat pipe","authors":"","doi":"10.1016/j.applthermaleng.2024.124358","DOIUrl":"10.1016/j.applthermaleng.2024.124358","url":null,"abstract":"<div><p>Future space exploration technology requires a long-life and reliable power source that is not reliant on solar energy. Space micro-reactors are able to meet this need, with Heat Pipe Cooled Reactors (HPR) emerging as a notable type of space micro-reactor that has attracted widespread attention in recent years. The HPR utilizes high-temperature alkali metal heat pipes for heat transfer, which presents certain complexities due to the solid state of the alkali metals working medium at room temperature. This results in a three-phase transition during the high-temperature heat pipes start-up process, which significantly impacts the heat transfer characteristics and dynamic behavior of the HPR start-up process. Consequently, thorough research is necessary in this area. Numerical simulation is a crucial tool that can effectively analyze, predict, and guide experiments. This article utilizes the Finite Volume Method (FVM) to develop a simulation code for high-temperature heat pipe frozen start-up. Various physical models are integrated to describe different components of the heat pipe: the container is represented by a two-dimensional axisymmetric heat conduction equation, the wick region utilizes a Fixed Grid Method (FGM) to depict the melting process of the medium, and the vapor channel is described through a two-dimensional axisymmetric compressible laminar flow. The wick region and vapor channel are coupled through the evaporation and condensation of the medium. For the vapor channel, numerical methods such as SIMPLE and PISO are used for solving. Adaptive time step and OpenMP acceleration are employed in the code to enhance computational efficiency. Finally, by comparing the calculated results with experimental data, the feasibility and accuracy of the code are assessed, highlighting special phenomena during the start-up process. The findings confirm that the developed code accurately predicts parameter changes during start-up, and can serve as a heat pipe analysis module for multi-physics coupling analysis of HPR.</p></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167235","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}

{"title":"Performance simulation and energy efficiency analysis of multi-energy complementary HVAC system based on TRNSYS","authors":"","doi":"10.1016/j.applthermaleng.2024.124378","DOIUrl":"10.1016/j.applthermaleng.2024.124378","url":null,"abstract":"<div><p>The failure rate and operating cost of the C-B (chiller-gas boiler) system, which has been in use for a long time, are increasing year by year, but there is a lack of reasonable programs and effective measures on how to retrofit the C-B system. In order to explore the prospect of ground-source heat pumps applied to the retrofit of C-B systems in HSCW (hot summer and cold winter) zone, this study designed a G-C-B (GSHP-Chiller-Boiler) system in a partial retrofit context and constructed a TRNSYS numerical simulation model of the retrofit system. Secondly, the performance and energy efficiency of the system is analyzed as well as different control strategies for the ground source heat pump cooling tower are discussed. Finally, the energy conversion efficiency of the chiller is compared based on the energy flow of the system. Studies have shown that the G-C-B system can achieve a seasonal performance factor of 5.3 during the cooling season and 4.1 during the heating season. Compared to the existing C-B system, year-round electricity consumption was reduced by 21 %, gas consumption by 92 %, and combined energy demand by 49.6 %. With the addition of GSHP, the energy conversion efficiency of the chiller has also increased by 21 %. The soil temperature of the G-C-B system increased by less than 0.5 °C after ten years of continuous operation. This paper can provide a valuable theoretical basis for the energy form modification of the C-B system in the HSCW zone.</p></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142164036","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}

{"title":"A simplified method of calculating heat flow through a heat exchanger with a significantly temperature-dependent specific heat of heat transfer fluids","authors":"","doi":"10.1016/j.applthermaleng.2024.124349","DOIUrl":"10.1016/j.applthermaleng.2024.124349","url":null,"abstract":"<div><p>A simplified method of calculating the heat flow through a heat exchanger in which one or both heat-carrying media have a specific heat that varies significantly with temperature is proposed. The proposed method allows for the calculation of the maximum heat flow rate provided that the thermodynamic properties of both heat carriers are known. It is intended for the simplification of heat exchanger modeling at the pre-design power plant simulations, which are used for the assessment of efficiency and the selection of schematic solutions. This is particularly relevant when the parameters of the heat exchangers are not known. The proposed method may prove useful for the simulation of binary cycle geothermal power plants, as well as for the modeling of gas turbine power plants utilizing carbon dioxide as the working medium for their cycles.</p></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167265","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}

{"title":"Scaling the turbulent jet by active pre-chamber","authors":"","doi":"10.1016/j.applthermaleng.2024.124359","DOIUrl":"10.1016/j.applthermaleng.2024.124359","url":null,"abstract":"<div><p>Recently, pre-chamber turbulent jet ignition technology has attracted many attentions as a means of improving combustion efficiency in alternative fuel engines. Pre-chamber engines span a wide range of bore diameters and power outputs, and scaled model experiments based on similarity theory can promote the intensification of research and development for pre-chamber engines with different sizes. While the similarity of turbulent jet development plays the most important role in the entire scaled model experiments, relevant research in this area is scarce. In this paper, for the first time, the theoretical analysis of pre-chamber turbulent jet similarity is carried out based on the similarity theory and gas jet theory. Then, the constant-volume combustion chamber and the high-speed double-pass schlieren imaging are implemented to study the similarity of turbulent jets from two pre-chambers with the orifice diameters of 2.12 mm and 1.50 mm. The results show that controlling the spark timing is an effective method to ensure the same jet ejection timing and pressure building processes during the development of the turbulent jet. Finally, it is found that the jet penetration, jet angle and projection area can be well scaled using the proposed similarity law. These results agree well with the theoretical analysis.</p></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163425","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}

{"title":"Unsteady flow and thermal dynamic performance of pre-compression characteristics in variable-speed scroll compressors","authors":"","doi":"10.1016/j.applthermaleng.2024.124327","DOIUrl":"10.1016/j.applthermaleng.2024.124327","url":null,"abstract":"<div><p>In the suction process of scroll compressors, a special thermodynamic phenomenon occurs, known as pre-compression, which significantly affects the inhalation capacity, volumetric efficiency, and thermal characteristics of scroll compressors. To explore its generation and impact, unsteady flow field distributions of the pre-compression phenomenon were obtained by numerical simulations. The pressure variation of the pre-compression phenomenon in air was analyzed, and the power consumption caused by pre-compression during the working process was investigated. Study results indicated that the pre-compression phenomenon is mainly produced by the geometric structure and operating features of the scroll compressor. The initial angle of the pre-compression phenomenon decreases by 31° as the rotational speed ranges from 3000 to 7000 r/min. The generation of the pre-compression phenomenon induces eddies in the suction chamber. Additionally, it was demonstrated that during the suction process, mass flow rate increases owing to the pre-compression phenomenon. The study is helpful for analyzing the suction process and improving operating efficiency of scroll compressors.</p></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142172893","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}