Temperature Standard Deviation Research Articles

Thermal Analysis of Jet-In-Crossflow Technique for Hotspot Treatment in Electronics Cooling

Abstract Artificial intelligence and machine learning systems, faster processors, miniaturized computational components, and supercomputer centers are accompanied by larger heat dissipation and the need for innovative cooling methods. In this work, a combined jet-in-crossflow cooling system is introduced and numerically investigated with an application in localized hotspot treatment. A validation study, a grid independence study, and an uncertainty analysis are conducted to ensure the accuracy of the obtained results. Both vertical and angled jet impingement at different jet locations are studied indicating the advantage of using a 45° angled jet placed upstream of the hotspot. In addition, the advantage of jet-in-crossflow in comparison with pure crossflow and pure jet impingement are studied. The results show that the angled jet-in-crossflow setup, in comparison with pure crossflow at the same overall mass flow rate, considerably reduces the temperature values at the heated surface, decreases the temperature standard deviation by 65%, while lowering the required pumping power by 35%. In comparison with pure jet impingement at the same overall mass flow rate, the angled jet-in-crossflow method reduces the required pumping power by 87%, while local temperature and temperature standard deviation values are very comparable. Furthermore, the advantage of structured rib channels in cooling effectiveness is investigated for the jet-in-crossflow setup. Although the addition of a rib slightly increases the pressure drop, the employment of a proper rib size minimizes the increased pressure drop while considerably improves the cooling effectiveness and temperature uniformity.

Lithium-ion battery pack thermal management under high ambient temperature and cyclic charging-discharging strategy design

To ensure the stable operation of lithium-ion battery under high ambient temperature with high discharge rate and long operating cycles, the phase change material (PCM) cooling with advantage in latent heat absorption and liquid cooling with advantage in heat removal are utilized and coupling optimized in this work. Based on the preferred hybrid cooling scheme, the two layers cold plates and fins are arranged, and the cold plate structure is redesigned to optimize cooling system. The coupling effects of composite PCM and water flow rate, as well as charging and discharging strategy, are numerically studied. The results show that the hybrid cooling is more suitable to high discharge rate of 5C and long-term cyclic operation at 40 °C. The two layers cold plate and fins arranged in hybrid cooling system can mitigate the temperature non-uniformity of batteries along the axis, and the maximum temperature Tmax and temperature difference ΔTmax are reduced by 4.44 °C and 4.17 °C, respectively. Also, the optimized cold plate can mitigate the temperature non-uniformity caused by battery dispersion, and the standard deviation of temperature of batteries is reduced from 0.48 to 0.37. Then, the composite PCM added with expanded graphite can further decrease the Tmax and ΔTmax by 2.18 °C and 1.79 °C, respectively. Lower charging rate offers more reliable cooling performance during continuous cyclic operations. In general, the designed fin-enhanced hybrid cooling system with composite PCM and two layers cold plate can control the Tmax and ΔTmax within 45.85 °C and 3.39 °C at 40 °C ambient temperature and 5C discharge respectively, and offers a reliable and desired cooling performance during continuous charging and discharging of 1C, 2C and 3C. During cyclic operation with 3C discharging and 1C charging, the Tmax and ΔTmax can be controlled below 44.39 °C and 2.64 °C, respectively.

Microchannel cooling plates with non-uniform airfoil fin arrangement for large-capacity marine battery: An experimental study

In the process of charging and discharging, the heat generation of the battery is uneven, which is more obvious for large-capacity batteries. To maintain the performance of the battery, the thermal management system based on the cooling plate is of critical importance. In this paper, the non-uniform airfoil fins arrangement of microchannel cooling plates for marine large capacity battery thermal management are designed and tested. The cooling performances of the uniform airfoil fins arrangement (UAFA), non-uniform airfoil fins arrangement 1 (N-UAFA 1) and non-uniform airfoil fins arrangement 2 (N-UAFA 2) are experimentally investigated. The maximum temperature (Tmax) and temperature standard deviation (SD) of battery module during charge and discharge process are compared with the variation of the volume flow rate (qv), the cooling water inlet temperature (Tin) and the charge–discharge rate (CR). The experimental results demonstrate that increasing qv and decreasing Tin would contribute to lower Tmax but higher SD. Both Tmax and SD increase with the CR increasing. The cooling effectiveness of the non-uniform airfoil fins arrangement is validated by the reduced Tmax and the robustness in SD control. In particular, the newly designed N-UAFA 2 microchannel could relief the contradiction between cooling capacity and the temperature uniformity. For all the working conditions, the N-UAFA 2 exhibited the best performance. Especially at the CR of 0.5C, the N-UAFA 2 could manage the Tmax and the SD below 36.8 °C and 1.5 °C, respectively.

Heat transfer investigation on the thermal energy storage using phase change material in low-carbon building

The use of high-conductivity porous medium is an effective method to enhance the heat transfer rate of phase change material (PCM) in thermal energy storage (TES), reducing the energy consumption of low-carbon buildings. This paper establishes a solid-liquid phase change lattice Boltzmann model of a TES unit and investigates the effects of Rayleigh number, inclination angle, porous array, and porosity. The findings indicate that inserting the porous medium enhances conductive heat transfer and weakens convective heat transfer. When the Rayleigh number is increased from 103 to 104, the liquid fraction increases by 3.0%, while an increase from 104 to 105 only results in a 1.6% increase, suggesting a diminishing effect of increasing the Rayleigh number. Results also show that the inclination angle can be disregarded in this study. Furthermore, increasing the specific surface area enhances conductive heat transfer. However, when the array n is changed to 7, the fastest variation of liquid fraction is obtained among the range from 5 to 9. Increasing the porosity will delay the moment that temperature standard deviation reaches to the maximum, getting the temperature distribution more nonuniform. The findings from this paper are valuable for the design of TES systems in low-carbon buildings. Practical application The porous medium can enhance heat transfer in the phase change process. In the field of low-carbon buildings, porous medium is applied to strengthen the energy storage rate. By investigating the parameters of the Rayleigh numbers, inclination angles, porosities and arrangement of porous medium arrays of the composed energy storage unit, the regularity of the effects on the energy characteristics are obtained, which would provide some valuable practice references for designing these parameters of the energy storage units in the future energy-efficient building sector.

Comparative study of combustion and thermal performance of a meso-scale combustor under co- and counter-rotating fuel and oxidizer swirling flows for micro power generators

Direct energy conversion systems, such as thermophotovoltaic and thermoelectric generators, have received increasing attention in micro power generation. Micro and meso-scale combustors are one of the most core components in these systems. So, developing combustion stabilization technologies for micro or meso-scale combustors is of great importance. In these systems, a hydrocarbon fuel with high energy density is burned in a micro or meso-scale combustor. Many studies have been conducted to explore various combustion stabilization techniques, but as a novelty, in this work, we study the combustion and thermal performance of a meso-scale micro power generator powered by a swirling fuel jet discharging into a co- or counter-rotating air coflow. To do so, we used 3D-printed axial swirlers with double annulus to form the swirling co- and counter-rotating fuel (methane) jet-air coflow configurations at various air and fuel flow rates. Blow-out limit, flame characteristics, combustor mean outer wall temperature, pollutant emissions, emitter efficiency, and normalized temperature standard deviation are investigated in this study. The results show that swirl addition enhances the blow-out limit significantly and co-rotating swirling flows generally enhances the flame blow-out limit when compared with the counter-rotating swirling flows mode at high fuel flow rates. Moreover, the combustor with co-rotating swirling flows has shorter lift-off height and longer flame length. The sensitivity of the flame lift-off height to an increment of the fuel mass flow rate is smaller in co-rotating than in counter-rotating swirling flows (more than 40%). Furthermore, it is observed that under the same operating conditions, co-rotating swirling flows exhibit lower values of CO and NOx in the flue gas and higher values of mean outer wall temperature, combustion efficiency, emitter efficiency, and normalized temperature standard deviation. The enhancement of the emitter efficiency by implementing co-swirl configuration is about 35%, 26%, and 8% for the methane flow rates of 0.050, 0.100, and 0.150slpm, respectively when compared with the counter-swirl mode. The results of this work can provide useful information to choose between co- and counter-rotating flows for combustors of combustion-based micro power generators.

Numerical identifications of T-shaped rod effect on thermal performance and exergy efficiency in methane/air combustion

To maximize the power output of micro-thermophotovoltaic systems, achieving a high and uniform wall temperature is desirable. Towards this goal, this work proposes a novel combustor with inserting a T-shaped rod and assesses the effectiveness of such a strategy in determining the thermal and exergy performances with a validated computational model. Results indicate that introducing such strategy results in a 50.4 K wall temperature elevation and a 30.5 % decrease in the temperature standard deviation at the inlet velocity of 0.6 m/s. The effectiveness of applying a T-shaped rod on wall temperature is also found to be dependent on the inlet velocity. In addition, the optimal equivalence ratio associated with the highest wall temperature is shown to be stoichiometric caused by the relatively larger volumetric thermal power density. Further analysis of the pressure loss and exergy energy is performed. While the presence of a T-shaped rod can lead to an increase in the pressure loss, these are negligible relative to the ambient pressure. Furthermore, in addition to the temperature enhancement, the T-shaped rod combustor is associated with a higher exergy and exergy efficiency, which is beneficial to improving the energy efficiency of combustion devices. This work provides valuable insight into enhancing the wall temperature and energy conversion efficiency for micro-power systems.

A multi-laser hybrid absorption sensor for simultaneous measurement of NH3, NO, and temperature in denitrification flue gas

The real-time monitoring of NH3, NO, and flue gas temperatures is critical to controlling NOx emissions from coal-fired power plants, reducing ammonia slip, and realizing accurate ammonia injection. However, few previous studies have utilized laser absorption sensors to measure these three indicators simultaneously. In this paper, a multi-laser hybrid sensor is designed based on tunable diode laser absorption spectroscopy (TDLAS) for simultaneous measurement of NH3, NO, and flue gas temperature. The sensor uses a distributed feedback (DFB) laser to target the NH3 and the H2O lines, and a quantum cascade laser (QCL) is used to target the NO line. In the measurements of NH3 and NO using calibration-free wavelength-modulated spectroscopy (CF-WMS), we employ a method to obtain the laser wavelength response by fitting the demodulated signal of a standard gas. Additionally, temperature measurements are obtained using the time-division multiplexing (TDM) strategy and direct absorption spectroscopy (DAS) techniques with the help of the absorption spectrum of H2O. Under static conditions, the relative accuracy of NH3 and NO detected by the sensor is 4.2% and 2%, respectively, and the maximum relative standard deviation of temperature is 1.3%. When tested under flowing conditions, the sensor can accurately capture NH3, NO, and temperature changes. The relative accuracy of NH3 and NO is 4.7% and 2.2%, and the relative standard deviation of temperature is 0.9%. The sensor has great potential in optimizing denitrification processes in thermal power plants.

Similar temporal patterns in insect richness, abundance and biomass across major habitat types

Abstract While many studies on insect diversity report declines, others show stable, fluctuating or increasing trends. For a thorough understanding of insect trends and their effects on ecosystem functioning, it is important to simultaneously assess insect richness, abundance and biomass, and to report trends for multiple taxa. We analysed insect richness, abundance and biomass data for all insects and for eight insect taxa (Buprestidae, Cerambycidae, Carabidae, other Coleoptera, Aculeata, other Hymenoptera, Heteroptera and Lepidoptera) from 42 sites across Switzerland from 2000 to 2007, representing three major habitat types in Switzerland (agricultural, unmanaged [open and forested] and managed forest habitats). As potential drivers of temporal patterns, we evaluated weather‐ and land‐use‐related factors. As predictors, we included temperature and precipitation as well as the vegetation index and the habitat type, respectively. We found a consistent pattern of stable or increasing trends for richness, abundance and biomass of insects in total and the eight taxa over 8 years. Both overall patterns and six out of eight taxa (except for Cerambycidae and Lepidotpera) showed the highest values in agricultural habitats. However, when accounting for elevation, there was no difference in open habitats regardless of whether they were used agriculturally. Habitat types were the most important predictors, followed by weather‐ and vegetation‐related factors. Modelled responses to mean temperature were unimodal, whereas the standard deviation of temperature showed positive and precipitation negative effects. Longer time series are needed to draw robust inferences and to investigate potential negative effects of future warming.

CFD simulation study of flow equalisation plate model in single-phase immersion liquid cooling for servers

Immersion liquid cooling is progressively being adopted for server cooling applications within data centers. Uneven coolant distribution in liquid-cooled cabinets may cause large temperature difference between servers under some extreme conditions, prompted this study on a flow equalization plate structure. Firstly, the servers, the cabinet and the flow equalisation plate were modelled using Ansys Icepak software, and then the effects of holes radii, inlet layout configurations, and the number of holes on the flow distribution of the FC-40 coolant and the temperature control across servers was investigated. The results indicate that the smaller radii is beneficial in balancing the flowrate within the holes of the flow equalization plate by increasing the flow resistance, yielding a maximum temperature difference and a maximum temperature standard deviation of 2.1 °C and 0.8 °C at r = 7.5 mm. However, excessively small radii can lead to higher internal pressures and flow resistance. With larger hole radii, temperature control is significantly influenced by the inlet flowrate. As the flowrate increases, ΔT and Tsd also increase, reaching up to 3.8 °C and 1.3 °C at r = 12.5 mm, respectively. Larger hole radii result in smaller coolant flowrate, leading to lower convective heat transfer coefficient and higher server temperature. Locating inlets on one side creates large low-velocity vortex areas, disrupting server cooling, while center placement enhances thermal performance. When the number of holes is 18, the hole spacing increases, which leads to an increase in the flowrate in the holes and an increase in the convective heat transfer coefficient, which improves the thermal performance factor ε to 1.04.

A comprehensive numerical study based on topology optimization for cooling plates thermal design of battery packs

This article focuses on the problem of fluctuating cooling system flow caused by different working states such as acceleration and braking during the actual operation of electric vehicles, which prevents the system from effectively dissipating heat from the battery for a long time. In the past, liquid cooling heat dissipation schemes designed based on structural parameters often relied on the experience of CFD engineers. There is no in-depth study of the heat propagation characteristics. At present, research on the application of topology optimization method in cooling plate design mainly focuses on the relative positions of single inlet and outlet, objective functions, and constraint conditions. There are very few studies evaluating the adaptability of different cooling plate structures at different flow rates. In this perspective, this work proposes a two-dimensional topology optimization method for obtaining the cooling plates with different topological structures such as the series of cooling plate structures with dual entrances and exits. The method comprises of a comprehensive study on variations of the inlet flow rate under different average fluid volume fraction, outlet width, and temperature weight conditions. The results indicate that setting an excessive inlet flow rate can actually lead to an increase in the average temperature of the optimized cooling plate. Subsequently, the cooling plate structure obtained through topology optimization at inlet flow rates of 0.015 m/s, 0.02 m/s, and 0.025 m/s was selected, and a three-dimensional electrothermal fluid coupling model was established based on its two-dimensional channel structure. Its cooling performance, flow characteristics, and heat transfer characteristics were analyzed, and compared with two straight channel reference models. The results indicate that the optimized cooling plate structure under low flow conditions has better heat dissipation performance. At a flow rate of 0.56 × At 10-6m3/s, compared to traditional cooling plates(CASE D, CASE E), the highest temperature of the battery using topology optimized cooling plates (CASE A) decreased by 3.5 K and 1.79 K, respectively, and the standard deviation of temperature decreased by 48% and 14%, respectively. Under the same inlet flow velocity, the area of the fluid region increases with the increase of the mean fluid volume fraction, and the width of the flow channel increases gradually and the branches increase significantly, from the concentrated solid region to the dispersed isolated region. At a low flow rate, the normalized temperature of the cooling plate increases with the increase of the flow rate of the coolant inlet, and when the flow rate reaches a certain value, in order to reduce the power loss of the cooling plate, the flow path is gradually concentrated on both sides of the cooling plate. This leads to the decline of the normalized temperature of the cooling plate.

Climate change linked to vampire bat expansion and rabies virus spillover

Bat‐borne pathogens are a threat to global health and in recent history have had major impacts on human morbidity and mortality. Examples include diseases such as rabies, Nipah virus encephalitis, and severe acute respiratory syndrome (SARS). Climate change may exacerbate the emergence of bat‐borne pathogens by affecting the ecology of bats in tropical ecosystems. Here, we report the impacts of climate change on the distributional ecology of the common vampire bat Desmodus rotundus across the last century. Our retrospective analysis revealed a positive relationship between changes in climate and the northern expansion of the distribution of D. rotundus in North America. Furthermore, we also found a reduction in the standard deviation of temperatures at D. rotundus capture locations during the last century, expressed as more consistent, less‐seasonal climate in recent years. These results elucidate an association between D. rotundus range expansion and a continental‐level rise in rabies virus spillover transmission from D. rotundus to cattle in the last 50 years of the 120‐year study period. This correlative study, based on field observations, offers empirical evidence supporting previous statistical and mathematical simulation‐based studies reporting a likely increase of bat‐borne diseases in response to climate change. We conclude that the D. rotundus rabies system exemplifies the consequences of climate change augmentation at the wildlife–livestock–human interface, demonstrating how global change acts upon these complex and interconnected systems to drive increased disease emergence.

Numerical investigation of a novel cold plate design with uniform circular hollow fins for battery thermal management systems

Cooling plate design plays an important role in an efficient battery thermal management system (BTMS). An effective cooling plate should have a low cost, lightweight, and dissipate heat with minimal pressure drop. Therefore, in this study a new lightweight cold plate design with circular hollow fins is proposed and heat generation is validated by experiment. A 3D numerical model is developed and the performance of the cold plate is evaluated by maximum temperature, temperature standard deviation, mass and power consumption. Firstly, the effects of structural parameters like fins diameter, the distance between hollow fins, cold plate thickness, and flow rate on the battery maximum temperature, temperature standard deviation, and pressure drop are studied. The results indicate that increasing the size of the hollow fins reduces the cold plate mass and leads to lower battery temperature, whereas the pressure drop increases. When the distance between hollow fins decreases more heat is taken away by the coolant. Furthermore, the performance of the optimized cooling structure is compared in terms of maximum temperature, temperature difference, mass of cooling plate, and power consumption with conventional liquid cooling structures under the same operating conditions. The results indicate that the optimized cooling structure can reduce the maximum temperature, temperature difference, mass of the cooling plate and power consumption by 6%, 29%, 55.2%, and 85.9%, respectively.

CFD-DEM investigation of flow and heat transfer characteristics in a directly irradiated fluidized bed

The directly irradiated fluidized bed reactor has gained widespread attention due to its strong heat and mass transfer performance. However, there is still a lack of in-depth understanding of the gas–solid flow characteristics, heat transfer mechanisms, and flow pattern evolution in the fluidized bed. To address this, the computational fluid dynamics-discrete element method (CFD-DEM) was employed in this study to investigate the correlation between the flow pattern and the heat transfer path. The simulation results show that increasing the superficial gas velocity from the minimum fluidization velocity (umf) to 1.4umf induces a circulation pattern that significantly reduces the overheating phenomenon, resulting in a 40.52% decrease in the maximum particle temperature and a 74.59% decrease in the temperature standard deviation. The particle temperature increases in the top heat-collecting region, followed by thermal conduction and convection transferring the energy to low-temperature particles and fluid in the near-wall and bottom regions. As the superficial gas velocity increases, the proportion and frequency of particles entering the heat-collecting region increase, resulting in a more uniform temperature distribution within the bed. Taking into account factors such as heat transfer characteristics and fluidization energy consumption, a fluidization velocity of 1.6umf is recommended as the optimum operating condition for particles in this work, as it ensures a uniform temperature distribution within the bed and minimizes convective and radiative losses.

An inverse methodology to estimate the thermal properties and heat generation of a Li-ion battery

Accurate estimation of temperature-dependent orthotropic thermal properties and volumetric heat generation of a Li-ion battery is crucial for thermal modeling, thermal safety, and the design of thermal management systems for electric vehicles. Though various studies are available on estimating thermophysical properties and heat generation, simple and easily applicable methods are rare. Moreover, these studies failed to report temperature sensitivity and standard deviation of the estimates. In this study, the temperature-dependent orthotropic thermal conductivities (kr,kθ,kz), specific heat (cp), and volumetric heat generation (qv) of Panasonic NCR18650BD cylindrical battery are estimated using an inverse approach (Metropolis Hastings-Markov Chain Monte Carlo algorithm based Bayesian method) with the help of experimentally obtained surface temperatures measured at convenient locations on the battery. From the estimation, the average values of kr,kθ,kz and cv are observed to be 3.18 ± 0.19, 20.34 ± 1.26, 19.89 ± 1.29 (W/mK), and 3180 ± 202 (J/kgK), respectively. The average heat generation rates from the same battery obtained using the same methodology are 0.1 ± 0.005, 0.34 ± 0.012, and 1.51 ± 0.026 W for 0.5, 1, and 2C discharge rates, respectively. The estimated thermophysical properties and heat generation rates are in good agreement with the results obtained from both in-house experiments and literature. In addition to the estimation of thermophysical properties and heat generation, the proposed methodology opens vistas to predict the strength and location of hotspots in the battery domain, which helps in designing appropriate and effective thermal management systems for battery packs.

Effect analysis on combustion performance enhancement of the hydrogen-fueled micro-cylindrical combustors with twisted tapes for micro-thermophotovoltaic applications

The main part of a micro-thermophotovoltaic (MTPV) system is the micro combustor (MC). In this work, the performance of the traditional micro combustor (TMC) and the micro combustor with twisted tape (MCTT) is investigated numerically under various inlet velocities (9 m/s-12 m/s), H2/air equivalence ratios (0.7–1.0), lengths of the twisted tape (4 mm–16mm), and pitches (4 mm, 5.33 mm and 8 mm). The results show that compared with the TMC, the MCTT with a 16 mm long twisted tape has a 114.7 K, 12.2 W and 15.0% increase in the mean outer wall temperature T¯w, radiation power Pemitter and emitter efficiency ηmc, respectively, at vin = 9 m/s. The outer wall temperature Tow is more uniform when the length of the twisted tape is 4 mm or 8 mm, the maximum drop in temperature standard deviation is 38.9 K when vin = 9 m/s. When the equivalence ratio φha is less than 0.9, the ηmc is not significantly improved with the increase of the length of the twisted tape. Overall, the MCTT offers better promise for applications in MTPV systems than the TMC.

Multi-objective optimization of a combined heat sink with triangular protrusion and corrugated surface impinged by a nanofluid slit-confined jet

Improving temperature uniformity and heat transfer capacity is crucial for the application of a jet-impingement heat sink in dissipating heat from high-power electronic devices. Therefore, a combined heat sink with a triangular protrusion in the stagnation zone, a corrugated surface in the wall-jet zone, and an oblique angle of the upper plate impinged by a nanofluid jet is proposed. A two-dimensional model is established, using Al2O3-H2O nanofluid as coolant. The effects of the structural parameters of the heat sink, the volume fraction of the nanofluid on the temperature uniformity of the heat sink and the jet-impingement heat transfer were studied numerically. Meanwhile, the structure of the heat sink is optimized by the NSGA-II genetic algorithm. The results indicate that the three structures can enhance both the temperature uniformity and the heat-transfer capacity. Using nanofluids with a 3%volume fraction and a Reynolds number of 8,000, the average Nusselt number of the optimal structure is 26 % greater than that of a jet impingement flat heat sink, the temperature standard deviation is 67 % less, and the friction coefficient and thermal-hydraulic performance factor are greater by 55 % and 9 %, respectively. Meanwhile, the optimized structure exhibits excellent heat dissipation and temperature uniformity at higher heat flux. The allowable maximum heat flux reaches 341 W/cm2 when the junction temperature of the hot spot does not exceed 348 K, and the temperature standard deviation is 2.926, which are increase by 83 % and decrease by 36 % compared with that of jet-impingement plate heat sink, respectively.

Optimization design of the forced air-cooled battery thermal management system with a stepped divergence plenum

In order to improve heat dissipation performance of battery pack with air-cooled structure, a novel stepped divergence plenum in Z-type air-cooled structure is proposed in a prismatic battery pack. Then the accuracy and effectiveness of computational fluid dynamics (CFD) model are verified by comparison with experimental results. Subsequently, the effects of the total height of all steps and the height of every step on the maximum temperature, temperature difference and temperature standard deviation of battery pack with air-cooled structure are explored, respectively. Finally, the stepped divergence plenum at different inlet airflow velocity is further optimized to achieve better cooling performance. Numerical results indicate that 1) For the larger total height of the steps, the stepped divergence plenum is suitable for Z-type air-cooled structure, and the stepped divergence plenum is better than the slanted one in the aspect of cooling efficiency while the latter is superior to the former for the smaller total height of the steps 2) Compared with the slanted divergence plenum, a stepped divergence plenum improves the heat dissipation performance of the battery for Z-type air-cooled structure. 3) The height of every step and inlet airflow velocity plays an important role in the cooling performance of the battery. The optimization results are h = 0.125 (i.e, Hopt = [1.39, 2.51, 2.51, 2.02, 2.02, 1.89, 1.76, 1.39, 1.51]) and 3 m/s, and the corresponding maximum temperature, temperature difference and temperature standard deviation of the battery pack are respectively reduced about 34.65 %, 77.51 % and 99.04 % in comparison with those for Z-type model. The optimization scheme proposed in this work provides a design guideline to improve the cooling performance of the air-cooled structure.

Design and experimental study on wave-type microchannel cooling plates for marine large-capacity battery thermal management

In this paper, the wave-type microchannel cooling plates for marine large capacity battery thermal management are designed and tested. The cooling performances of the straight microchannel cooling plate (SMCP), the single-periodic wave microchannel cooling plate (SWMCP) and the double-periodic wave microchannel cooling plate (DWMCP) are experimentally investigated. The maximum temperature (Tmax) and temperature standard deviation (SD) of battery module during charge and discharge process are compared with the variation of the coolant inlet temperature (Tin), volume flow rate (qV) and the environmental relative humidity (RH). The experimental results demonstrate that decreasing Tin, increasing qV and decreasing RH would contribute to lower Tmax but higher SD. The cooling effectiveness of the wave-type microchannel cooling plates are validated by the reduced Tmax and the robustness in SD control. In particular, the newly designed DWMCP with the non-linear wave-type microchannel could relief the contradiction between cooling capacity and the temperature uniformity. For all the working conditions, the DWMCP could manage the Tmax and the SD below 41.5 °C and 0.96 °C, respectively.

Numerical study and performance analyses of counter flow minichannel heat sink with slots on ribs

Various minichannel heat sinks are developed to cope with the increasing demand for thermal dissipation of electronic equipment. However, with the rapid development of microelectronics technology, temperature uniformity has gradually become a thorny problem needing more attention. Counter flow minichannel heat sinks with slots on ribs (CSF) were designed to enhance heat transfer and improve temperature uniformity. A 3D conjugated heat transfer model was developed in laminar flow regime, water has been selected as the working fluid, the constant heat flux was applied on the bottom surface of minichannel heat sinks. The counter flow minichannel heat sinks with slots on ribs not only possess higher heat transfer capacity, but also have better temperature uniformity. The average Nusselt number maximum increases to 2.01 times and the maximum temperature of bottom surface reduces 14.6 K for counter flow minichannel heat sink with five slots on ribs (CSF5) compared with parallel flow minichannel heat sink at Reynolds numberRe = 904. The temperature standard deviation of bottom surface maximum reduces 4.3 K for CSF3 minichannel heat sink atRe = 904. The effect mechanism of setting slots on ribs on the performance of counter flow minichannel heat sink was analyzed, it can be attributed to (i) interrupting and re-developing thermal boundary layer, and (ii) heat transfer between adjacent channels in which working fluid flows in opposite directions. Due to more uniform temperature of bottom surface and better heat transfer performance, the novel minichannel heat sink has potential application for thermal dissipation of electronic equipment.

Heat Release Simulation Research Based on Solid Heat Storage and Release Materials

To promote the actual investment of solid electric heat storage heating devices, three different heat storage and heat release materials are used to simulate and analyze the heat release. The results show that “magnesia brick has the best heat storage and release capacity in 10 hours”. In terms of average temperature performance, silica brick is the best, and the standard deviation of temperature reaches the maximum value at 8 h, which is 75.13 k. It is less than the maximum value of 99.70 k for magnesia brick and 114.93 k for solid waste ceramic brick. However, the manufacturing cost of silica brick is the highest, and the cost of solid waste ceramic brick is the lowest. Solid waste ceramic bricks can be preferentially selected under the condition of meeting the requirements of heat storage and release.