查看更多>>摘要：The mist cooling system presents the ability of thermal management and hazard control for li-ion batteries， which can be developed into a compatible system with appropriate optimization。 However， to have deeper insight into the mist cooling system， its effectiveness on thermal runaway (TR) hazard control still needs further experimental investigation。 In this study， experiments have been conducted with the fine water mist (FWM) under TR conditions， and the influence of air velocity on hazard control has been discussed。 Compared with air cooling， the FWM cooling system presents the maximum improvement of 46 %。 The local evaporation cooling of the FWM droplets has been significantly weakened once the net droplets content reaches below 6。2 gm?3。 Based on the heat generation during cooling， the comprehensive total temperature increase has been proposed to characterize the hazard control effect。 Accordingly， the TR cooling control has been divided into three levels， and a conservative temperature of 240 °C is identified to guide the hazard control。 This work confirms the TR control capacity of the FWM cooling system， and the influence of air velocity and droplets content on cooling capacity has been demonstrated， indicating the possibility of practical utilization in real cases。
查看更多>>摘要：Swirl cooling with air/mist mixture coolant is a promising heat transfer method， for which the combined influence of swirl and mist should be clearly understood。 In this work， numerical simulations on the swirl cooling performance of the leading edge of a turbine vane using mist/air mixture and air are implemented for comparative study。 The Eulerian-Lagrangian particle tracking method is adopted to investigate the two phase cooling。 The coolant air impacts tangentially the inner surface of the circular swirl chamber through two rectangular nozzles， and the mists with different concentrations (5%， 10%， and 20%) and droplet diameters (1 μm， 2。5 μm， 5 μm， 7。5 μm， and 10 μm) are included to explore their effects on the cooling performance。 The results demonstrate that the circumferentially-averaged Nusselt number， Nucir， increases with the increase of mist concentration， and this effect becomes prominent when the droplet diameter increases。 For droplet diameter of 10 μm and mist concentration of 20%， Nucir can increase by 12。6% to 309。7% as compared to pure air。 In addition， the empirical correlations of the global-averaged Nusselt number， and friction coefficient to the mist diameter and mist concentration are given for the first time。 It is concluded that the thermal performance factor， which can be used to evaluate comprehensively the cooling characteristics， increases with the increase of mist concentration and droplet diameter。 The empirical correlations and thermal performance evaluation provide the basis for further theoretical analysis of the cooling performance using air/mist mixture。
查看更多>>摘要：As a key component in contact with the battery pack in the liquid-cooled system of electrical vehicle， cooling plate needs to achieve effective heat transfer while maintaining the temperature distribution uniformity of the battery pack。 In this paper， numerical analysis of the cooling plate structure adopted in an actual battery module is undertaken and verified by comparison with the experiment。 Three structural design schemes for the cooling plate are proposed and analyzed based on the thermal characteristics of the battery pack。 The results indicate that the temperature distribution of the battery pack is actually the result of the two-way coupling of the battery heating and liquid cooling process。 The temperature distribution uniformity of the battery pack can be effectively improved after the structural optimization of the cooling plate。 Compared to the original design， the maximum field synergy angle is reduced by 7。25%， while the cooling efficiency factor is increased by 10。82% for the uneven heating condition of the battery pack。 In addition， the temperature uniformity of the battery pack deteriorates as the discharge rate increases。 The overall optimization method for the uneven distribution of heat sources can be used as a reference for the structural design of the cooling plate。
查看更多>>摘要：A comparative study between two techniques of solar integration in Integrated Solar Combined Cycle system power plant in terms of thermal performances and economic assessment is carried out in this work。 The first system power plant is based on parabolic trough collector technology where solar heat is introduced in the steam power block as a latent heat and the second system runs with a solar power tower technology。 The latter integrates solar thermal energy as a sensible heat to heat up the flue gases from the gas turbine till the fired temperature before entering the heat recovery steam generator。 Thermodynamic investigations show high thermal performance for both thermal power plants， but the system plant with solar tower exhibits the best annual performances efficiency value of about 57。2%。 Furthermore， in terms of solar conversion to electricity， the plant based on solar tower reveals noticeable enhancements; almost constant values during the year of about 20。8% have been registered。 In terms of economic analysis， both power plants show approximately the same Levelized cost of energy of 0。0395 $/kWh and 0。0355 $/kWh for the plant based solar tower and that based parabolic collector respectively。
查看更多>>摘要：A novel design and an efficient operation of solar volumetric receivers remain critical for successfully integrating such receivers into solar energy harvesting devices。 The performance of the solar volumetric receiver is highly dependent on the geometric connectivity of the actual pore-sites in the SiC open-cell foams。 Although the performance of SiC foam receivers has been investigated previously considering the homogeneous foam structure， further studies are needed to explore the influence of the actual path of the pores and their connectivity on the flow and thermal performance of the receiver。 Hence， the present study considers the novel design of a solar volumetric absorber incorporating the actual SiC foam receiver geometric features。 Accordingly， the thermal and flow behavior of the working fluid within the receiver is examined considering the 3D connectivity of the pore sites。 Moreover， the performance of the solar volumetric receiver is evaluated for different Reynolds numbers， solar concentrations， and foam porosities。 A 3D-dimensional numerical investigation is carried out incorporating the interactions between convection， conduction， and radiation heat transfer for which the discrete ordinate radiation model is used。 Porous SiC foam is placed in a channel having an optically transparent wall at the top and air is used as the working fluid extracting heat from foam。 The overall heat transfer coefficient， normalized Nusselt number， and thermal effectiveness are evaluated for various operating conditions。 Findings revealed that the receiver thermal performance improves at high Reynolds numbers。 The convection heat transfer is found to be the apparent heat transfer mode within the porous SiC foam。 In addition， the pumping power to overcome the flow resistance in the channel is considerably less than that of the rate of heat transfer gain。
查看更多>>摘要：A two-layered control strategy is proposed for the air conditioning (AC) systems of electric vehicles。 Unlike traditional rule-based controllers such as the on–off controller and proportion-integral-derivative (PID) controller， this strategy includes a decision layer and a control strategy。 The core algorithm in the decision layer is the dynamic programming (DP)， which integrates information from the thermal habit predictor of the passenger， vehicle velocity planner， and weather information receiver。 The DP optimises the development of the cabin temperature to minimise the energy consumption of the AC system and sends the planned temperature to the control layer。 The control layer uses a fuzzy PID algorithm to adjust the compressor speed based on the planned temperature profile， such that the real-world cabin temperature approaches the planned temperature。 This two-layered control strategy is applied to a car whose AC-cabin system was verified by test data， and the results are compared with those obtained by the on–off controller and PID。 When the target cabin temperature is not manually adjusted， the energy cost of the proposed strategy is 28。2% and 5。4% lower than those of the on–off controller and PID， respectively， at the ambient temperature profile of Environment 1 (described herein)， and its maximum fluctuation of the cabin temperature is 92。8% and 68。2% smaller than those of the on–off controller and PID， respectively。 At the ambient temperature of Environment 2 (described herein， lower than that of Environment 1)， the energy cost of the proposed strategy is 37。1% and 5。9% lower， and the maximum fluctuation of the cabin temperature is 96。8% and 86。4% smaller， compared to the on–off controller and PID， respectively。 When the target temperature is repeatedly set for the on–off controller and PID (first to 20 °C， then to 24。3 °C)， the AC system consumes extra energy， leading to poor thermal comfort。 Because the proposed strategy automatically sets the cabin temperature to the temperature preferred by the passenger， there is no extra adjustment of the target and the thermal environment inside the cabin is optimal for the passenger。 Under this condition， the developed strategy can produce energy savings of 30。2% and 12。4%， compared to the on–off strategy and PID， respectively。 Thus， the two-layered strategy can control the cabin temperature precisely， provide the passenger with a good thermal environment， and produce energy savings for the AC system。
查看更多>>摘要：The application of hydrogen is considered to be an effectiveg way for decarbonising the iron and steel industry。 This research aims to quantifying the energy saving potential and environmental benefit of two hydrogen-based steelmaking processes through exergy analysis and life cycle assessment: hydrogen-enriched shaft furnace-electric furnace (HESE) process based on coal gasification and hydrogen shaft furnace-electric furnace (HSE) process based on water electrolysis。 It is estimated that the energy consumption and CO2 emission of the HESE process are 11。82 GJ/t and 1121。28 kg/t， achieving a 39。79% of energy-saving and a 45。42% of CO2 emission-reduction when compared with the blast furnace-basic oxygen furnace (BF-BOF) process。 The research goes further to evaluate the future HSE process of its energy saving potential and environmental benefit。 When renewable electricity is applied， the HSE process will have relatively low carbon emission (i。e。 120。92 kg)。 However， the energy consumption reaches 13。42 GJ with an exergy efficiency of 33。91%。 A key feature of the process lies in the power consumption， which can be balanced through the share of scrap used， and its future links with the prosperity of hydrogen economy。 The present work should do helpful effort to the carbon neutral goal of iron and steel industry。
查看更多>>摘要：This work aims to validate the hypothesis that refrigerant blends could allow energy savings in real refrigeration systems。 For that purpose， five selected blends have been evaluated as drop-in substitutes in a domestic fridge for fresh food designed for R-600a under laboratory conditions。 Mixtures， selected from an initial theoretical work， were subjected to a charge optimization process following the standard EN 62552-2:2020。 At their optimum refrigerant charge， three offered energy savings: 2。15% is obtained with the mixture R-600a/R-1234yf [92。5/7。5%]; 3。84% with R-1234ze(E)/R-600 [10。5/89。5%] and 1。31% with R-600/R-290 [89。0/11。0%]。 This work discusses the experimental procedure and the operating parameters of the selected mixtures in relation to R-600a。 Thus， it has been verified that energy savings could be obtained with refrigerant blends。 However， understanding the operation of the mixtures requires further investigation not covered in this work。
查看更多>>摘要：The liquid turbine can replace throttling valves during the depressurization process of high-pressure liquid or supercritical fluid and improve the system efficiency of many industrial systems。 However， there is no research about studying the internal flow and total pressure loss of liquid turbines， which can affect the turbine performance significantly。 In this paper， performance and flow characteristics in a liquid turbine were analyzed for supercritical compressed air energy storage (SC-CAES) systems in the first time。 Three typical topology models (C1， C2 and C3) of the tested liquid turbine were simulated and their performances were compared with experimental results。 The deviation of the turbine efficiency between C3 and the experiment was less than 2%， while C1 had a constant increment of the turbine efficiency about 15。8% with the experiment。 The total pressure loss in each part was evaluated and the flow characteristics in the nozzle and the rotor were analyzed。 Nonuniform flow affected the nozzle's total pressure loss significantly， while the rotor's total pressure loss was related to the development of low energy regions。 The results obtained in this paper provides guidance for optimizing liquid turbines and improving the turbine performance for various industrial systems with throttling valves installed。
查看更多>>摘要：In this article， a novel drying system incorporated with energy storage has been developed to operate on 24-hours basis and utilize renewable energy- solar and biomass as heat source。 Study of literature revealed that such a system has not been considered by past researchers。 There was also lack of experimental studies on heat and mass transfer in potato during intermittent drying; while the drying behaviour of chayote under intermittent conditions was entirely missing。 Therefore， impact of four heating/drying methods- constant hot air drying (CHAD)， constant vacuum drying (CVAD)， intermittent hot air drying (IHAD) and intermittent vacuum drying (IVAD) on heat and mass transfer， drying kinetics and physical attributes like shrinkage， porosity， bulk density and particle density were evaluated for two bio-products-chayote (Sechium edule) and potato (Solanum tuberosum)。 Results showed that the developed system was capable of operating without interruption of the drying process between day and night。 Intermittent drying had 16。7% lesser effective heating time but produced similar final moisture levels in the products。 The average drying rate for CHAD and IHAD were respectively 0。4935 and 0。4889 kg/kg-hr for potato and 1。25 and 1。11 kg/kg-hr for chayote showing a greater positive impact on potato as compared to chayote。
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Elsevier