Search

In the work, a composite cooling system coupled with PCM (phase change material) and liquid cooling was designed. The influence of parameters such as spacing, EG (expanded graphite) content, battery direction, coolant flow rate and pipe diameter on the cooling performance was analyzed. The results revealed that: (1) The increase of spacing makes the temperature of the pack decrease, but the effect degree of increasing the spacing on temperature performance decreases when the spacing exceeds 14 mm. At the same time, CPCM formed by the added high thermal conductivity material expanded graphite and paraffin can effectively improve the temperature control performance of the pack, which can control the temperature at 313.15K under the condition of an ambient temperature of 308.15K (2) By comparing the maximum temperature and the temperature difference of the pack under different discharge methods, it is concluded that the poles facing inward can reduce the accumulation of the interior heat. (3) The convective heat transfer coefficient and Nu number of the pack are increasing as the flow rate increases, but the slope of the temperature versus flow rate decreasing slowly. After increasing the inlet size, the inner wall surface area of the pipe increases and the average convective heat transfer coefficient of the pack reduces. However, the Nu number increases with the increase of the pipe diameter, indicating that the growth of the pipe diameter can enhance the heat transfer rate. (4) Orthogonal experiment and fuzzy correlation analysis were combined to analyze the parameters that affect the thermal performance of the BTMS. It was determined that using a proper coolant flow rate can maximize the thermal performance of the pack. • A composite cooling system coupled with PCM and liquid cooling is designed. • Influences of the key parameters on the cooling performance are analyzed. • Orthogonal experiment and fuzzy correlation analysis are used to analyze affecting parameters. • Some results for enhancing cooling performance are obtained. [ABSTRACT FROM AUTHOR]

Improper battery temperature will lead to reduced battery discharge efficiency and electric vehicle driving range. Endeavors to find an efficient and precise battery temperature control method for the transcritical CO 2 thermal management system of electric vehicles, two evaporation temperature control methods for battery cooling were proposed. First, the effects of the control methods on battery temperature, optimal discharge pressure and coefficient of performance (COP) were simulated under typical operating conditions. Subsequently, a comparative simulation was conducted on the battery temperatures and COP of the two control methods under full cooling conditions. The results revealed that equal evaporation temperature control induced a reduction in battery temperature to 11 °C (suboptimal levels) under conditions of low ambient temperature and vehicle speed. Conversely, while unequal evaporation temperature control could maintain the battery temperature within the optimal range of 20–45 °C, it would result in a maximum COP drop of more than 20% under certain conditions. Furthermore, the effects of the two control methods on driving range under different ambient temperatures and vehicle speeds were studied. The reasults indicated that the ultimate influence of uneuqal evaporation temperature control on the quarterly average driving range was virtually negligible, peaking at 1.35%. Given the dual-objective constraints pertaining to the driving range and the battery cooling performance, it was concluded that uneuqal evaporation temperature control was the optimal choice for direct battery cooling. • A transcritical CO 2 battery direct cooling thermal management cycle is studied. • The effects of battery temperature controls on driving range of EVs are evaluated. • Coupling effects of operation conditions and controls on driving range of EVs is revealed. • The optimal option for battery temperature control is recommended. [ABSTRACT FROM AUTHOR]

The temperature has a significant effect on the lifespan and the safety of the batteries which are one of the core components of electric vehicles. A well-designed battery thermal management system is required to adjust the temperature of the batteries within an appropriate range for thermal safety, and further minimize the energy consumption for energy savings. However, these two goals form a tradeoff. Typically, increased energy consumption for cooling results in safer batteries thermally. To examine this tradeoff, firstly, a linear electro-thermal model is built to evaluate the thermal dynamics of the operating battery-cooling module. The linear model accounts for the heat generation based on internal resistance, and the heat transfer based on a resistance–capacitance model. Such linear model reduces the computation of the model simulation to dynamically catch up with the change of temperatures and to implement control strategies on the cooling system in a short time. Based on this model, a model predictive control (MPC) framework is proposed to design thermal control methods, which considers both thermal safety and energy saving. The weight of these two goals can be adjusted to explore the tradeoff between them. Finally, we investigate the performance of the MPC framework by applying the Urban Dynamometer Driving Schedule (UDDS) to the battery module. The simulation results show that the electro-thermal model is effective for battery thermal dynamics evaluation. Additionally, the tradeoff between the two goals is demonstrated by the simulation. • A fast temperature prediction and closed-loop thermal control framework is proposed. • An electro-thermal model of an active-liquid-cooling battery module is developed. • A thermal prevention control strategy is proposed. [ABSTRACT FROM AUTHOR]

It is seen from this figure that the maximum temperature rise of the cell module decreases as the increasing rate of fluid flow. The maximum temperature rise of the cell module is under 40 °C and 36 °C respectively since the flow rate is 0.40 × 10−3 L·s−1 and 1.20 × 10−3 L·s−1, indicating that increasing flow rate increases the cooling capability of the LCP. • A new cooling plate is developed for controlling undesirable cell temperature field. • Inlet and outlet of cooling plate have big impact on cell temperature distribution. • Increasing flow rate decreases cell temperature rise markedly. • Cooling plate channel width has weak impact on cell temperature distribution. • Channel width has great effect on ratio of power consumption of cooling plate. The thermal management for a lithium ion battery cell plays a pivotal role in enhancing the cell performance and reliability for electric vehicles. In this work, a novel serpentine-channel liquid cooling plate with double inlets and outlets is developed for better managing an undesirable temperature distribution of a cell module. With a simplified model for the cell module, numerical analyses are implemented using the software of FloEFD to study effects of flow directions, flow rates and channel widths of the cooling plate on cell temperature distribution under different operating conditions; Likewise, a ratio of power consumption as a non-dimensional number is defined to analyze the hydraulic performance of the developed cooling plate. Results show that locations of the inlet and the outlet as well as flow directions have great impacts on the cell temperature distribution and the ratio of power consumption of the cooling plate. Increasing fluid flow rate substantially decreases the maximum temperature rise of the cell module while it has little effect on the temperature distribution. Moreover, the channel width of the cooling plate has a strong influence on its ratio of power consumption as well as the cell temperature distribution but it has a weak influence on the cell maximum temperature rise. Interestingly, the developed serpentine-channel cooling plate offers one a new method to design a lithium ion battery thermal management system for controlling temperature distribution of a cell module. [ABSTRACT FROM AUTHOR]

This paper provides a methodology to assess the average surface temperature of battery cells under realistic transient scenarios. Computational fluid dynamics modelling of battery cooling is conducted for the cases exposed to the ramps of internal heat generation inferred from the standard driving cycles. The results are then post-processed to determine the effectiveness of air and water as the coolant fluids. A quantitative measure of the maximum overshoot, dimensionless settling (DST), heating (DHT), and cooling (DCT) time is subsequently presented. It is shown that, compared to water, air produces a considerably delayed response to temporal changes in the internal heat generation and is slower at reaching the new steady state condition. Cooling battery cells by using water almost always ensures remaining within the safe operating range. Nonetheless, regardless of the coolant type, the long period ramps tend to produce smaller values of DST. The primary origin of the delay is the slow heat conduction within the battery cells. In addition, it is shown that water responds to changes in the internal heat generation far quicker during the heating and the cooling phases. The study highlights the importance of transient analyses for characterising the thermal behaviour of battery packs. • A novel measure of battery heat release due to internal heat generation is presented. • Transient cases with sharp gradients cause large delays in system response. • Air cases always produce an overshoot and are far slower at reaching steady state. • Battery cells remain within the safe operating range in almost all water cases. • Water cases react far quicker to changes in the internal heat generation. [ABSTRACT FROM AUTHOR]

• Composite PCM is designed by in-situ constructing phase changeable framework in PEG. • The novel composite PCM possesses dual phase change temperature regions (PCTRs). • The two PCTRs are precisely tailored at 31.7–42.1 ℃ and 42.1–51.2 ℃, respectively. • The lower PCTR ensures suitable working temperature for battery at normal operation. • The higher PCTR prevents thermal hazards of battery under high ambient temperature. The phase change material (PCM)-based battery thermal management technology still remains a contradiction of guaranteeing a suitable operating temperature (20–40 ℃) of the batteries under regular working conditions, while avoiding the malfunction of the PCM under high ambient temperature (>40 ℃). Therefore, a novel composite PCM (CPCM) possessing dual phase change temperature regions (PCTRs) is designed herein by in-situ constructing a phase-changeable polymer (PCP) framework in the polyethylene glycol (PEG)/expanded graphite (EG) slurry. As prepared, the lower PCTR at 31.7–42.1 ℃ from the PCP framework provides a latent heat of 35.0 J g−1, while the higher PCTR at 42.1–51.2 ℃ from the PEG offers a latent heat of 68.3 J g−1. Additionally, the nanoscaled PCP framework strongly adsorbs the PEG, preventing the leakage phenomenon (mass loss < 1%), and the uniformly dispersed EG endows the CPCM with a high thermal conductivity of 1.98 W m−1 K−1. In consequence, under the normal ambient temperature of 25 ℃, the lower PCTR effectively keeps the battery module operating within the suitable temperature range of 25.9–34.9 ℃ and with a low temperature difference (ΔT) of 2.4 ℃ at the discharge rate of 1C. For comparison, the battery module adopting classical CPCM with a single PCTR at 40.9–55.1 ℃ demonstrates a much higher temperature range and maximum ΔT at 28.0–40.9 ℃ and 4.8 ℃, respectively. Under the high ambient temperature of 40 ℃, the higher PCTR starts to work like the single PCTR of traditional CPCMs, and controls the T max and ΔT of the module below 49.2 and 2.2 ℃ at the discharge rate of 1C, respectively, preventing thermal hazards. [ABSTRACT FROM AUTHOR]

Battery thermal management (BTM) plays a significant role in the safety and reliability of autonomous underwater vehicles (AUV) at higher speeds. In this study, a nanoparticle/phase change material (nano-PCM) composite is proposed for the BTM of an AUV. The effects of nanoparticle loading percentage (φ = 5, 10, and 15%) and nanoparticle filling range (α = 30, 60, 90, and 120°) on the battery temperature and PCM melting were investigated numerically. Two criteria for the dimensionless temperature control performance (TCP) factor and dimensionless heat storage performance (HSP) factor were used to evaluate the influence of various variables on the BTM performance. The results show that increasing the nanoparticle loading percentage improves the effective thermal conductivity of the PCM but reduces the overall effective latent heat. An optimal nanoparticle filling range of α = 60° is recommended to accelerate the overall melting rate of the PCM. Compared with those of the pure PCM-based BTM, the TCP rate and TCP density are enhanced by 14.56% and 26.75%, respectively, at α = 60°. The HSP rate increases by 2.84% but the HSP density reduces by 11.85% at α = 60°. These findings can provide a reference for the accurate design of nano-PCM composites for the BTM of AUVs. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) are extremely sensitive to their temperature and therefore, require a battery thermal management system (BTMS). BTMS is commonly employed to prevent thermal runaway of the LIB pack by controlling their operating temperature. This review paper provides various cooling strategies, including active and passive approaches, utilized in BTMSs. Air-cooled, liquid-based, and PCM-cooled techniques are first reviewed. This article presents an assessment of the application of nanofluids and nano-phase change materials (nano-PCMs) in BTMSs to improve heat dissipation from the LIB pack. This work emphasizes the utilization of these materials to intensify their thermal conductivity and suggests further investigations on their application in BTMSs. • Lithium-ion batteries are extremely sensitive to their temperature. • BTMS is employed to prevent battery thermal runaway by controlling its temperature. • Providing various cooling strategies for BTMS: active and passive approaches. • Presenting an assessment of the application of nanofluids and nano-PCMs) in BTMSs. [ABSTRACT FROM AUTHOR]

• Lithium-ion battery module and thermal management interactions were simulated. • The system was thermally managed using fuel. • A comparative analysis was performed for verification and assessment. • N-heptane fuel was found as a feasible coolant in hybrid electric vehicle batteries. Battery thermal management system (BTMS) design is crucial for its performance, which can be associated with extra costs and system complexity. Most of the current studies are focused on the BTMS design but with a little focus on the improvement of coolants. In this work, the feasibility of using combustion engine fuel for the LIB thermal management of hybrid electric vehicles is investigated. N-heptane is used as a dielectric hydrocarbon coolant in the introduced system. The thermal performance of the proposed system is investigated numerically using the CFD software ANSYS-Fluent. To benchmark and validate the system performance, a comparative study is made among other common approaches, including the use of air and 3M-Novec 7200. A variety of input parameters are accounted for, including inlet velocities and discharge rates. The results show that air cooling is the least effective method to control the battery module temperature uniformity and the Li-ion battery safety limit. At the same time, n-heptane and 3M-Novec 7200 have shown good control of the module temperature range (20 °C–40 °C) at various discharge rates and different inlet velocities. However, using n-heptane is a considerable improvement to the cost of the system and reduction in its weight and maximum temperature, compared to that using 3M-Novec 7200 coolant. For instance, at 0.1 m · s - 1 , n-heptane has reduced the Li-ion battery maximum temperature at 1 C and 2 C discharge rates by more than 7.9 °C (2.6%) and 17.9 °C (5.65%), respectively, compared to those predicted using the same battery module without cooling. [ABSTRACT FROM AUTHOR]

Serious performance loss of lithium-ion batteries at subzero temperatures is the major obstacle to promoting battery system in cold regions. This paper proposes a novel heating strategy to heat battery from extremely cold temperatures based on a battery-powered external heating structure. The strategy contains two stages: preheating process for battery cold-start, and temperature holding process for battery temperature control after preheating. The strategy switches from the preheating to the temperature holding according to the power capability of battery pack. Both the electrical and thermal behaviors of battery pack are described based on equivalent circuit models, and the state-of-charge and state-of-power of battery pack are co-estimated online to support the implementation of the strategy. Systematic battery-in-the-loop tests are conducted for a series-connected battery pack to verify the effectiveness of the strategy at – 40 °C. Experimental results show that the battery pack can not only be heated from −41.4 °C to −14.0 °C in 371 s by consuming 6.1% of nominal capacity without being over-discharged, but also output 64.81% and 66.59% of nominal energy for loading the modified dynamic stress test cycles and the modified federal urban driving schedule cycles respectively after preheating. [ABSTRACT FROM AUTHOR]

The optimal performance of a Li-ion battery is directly impacted by temperature. In order to control the temperature rise and provide even temperature distributions in the battery pack, a thermal management scheme comprises thin heat sinks with multiple phase change materials (PCMs) and air channels is investigated in this paper. The cooling performance and temperature homogenization of the battery thermal management (BTM) system are carefully studied under various configurations of PCMs. The results show that increasing the air inlet velocity has less effect in suppressing the temperature rise at early discharge stage, but ameliorates as the discharge prolonged to 3600 s. The standard deviation of the temperature (STDV) and maximum temperature of the batteries can be decreased by arranging PCMs with a lower melting temperature at the midsection and a higher melting temperature at the air outlet region of the heat sinks. In addition, for volume fraction of PCMs, Case IV, having a PCM with a higher melting point adjacent to the air outlet region and occupying one-half the height of the heat sink, illustrates a lower temperature rise and decreases the maximum temperature in the battery module by 1.024 K, 2.186 K, and 2.553 K, compared to Case I, II, and III, respectively. • Multiple PCMs incorporated thin heat sinks for battery thermal management is proposed. • The thermal performance of the battery based on maximum temperature upsurge is investigated. • The distributions of PCMs based on melting point and latent heat were carefully explored. • The optimal design for the distribution of PCMs is obtained for the proposed battery. [ABSTRACT FROM AUTHOR]

It is becoming increasingly apparent that wide application of electric vehicles (EVs) are subject to significant improvements in battery technology. Temperature sensitivity is a major issue adversely affecting battery performance and requiring a robust thermal control. Yet, this is challenged by the large variety of temporal scenarios though which heat is generated in a battery pack, demanding dynamic tools to predict the thermal evolution of batteries. Classical transfer functions provide a low-cost and effective predictive tool. However, they are limited to linear systems, while nonlinear predictive tools can become impractical for EV applications. Therefore, this study provides a methodology to assess the dynamics of battery cooling. This is achieved through conduction of high fidelity modelling of battery cooling exposed to different temporal disturbances on the internal heat generation. The results are then post-processed to evaluate the extent of linearity. A quantitative measure of non-linearity is further applied to clearly determine the degree of nonlinearity in the heat transfer response. It is shown that battery cooling system can be approximated as a linear dynamical system as long as the disturbances are of short duration and relatively low amplitude. Conversely, long and large amplitude temporal disturbances can render strongly nonlinear thermal responses. • A novel measure of nonlinearity of battery cooling process is introduced. • Cooling process remains nearly linear at low load modulation amplitudes (10%). • Long duration temporal disturbances of the battery load generate strong nonlinearity. • For linear conditions, transfer function of Nu is like a low-pass filter. [ABSTRACT FROM AUTHOR]

Air-cooled battery thermal management system (BTMS) is universally adopted in electric vehicles for temperature control of battery packs. In the present study, we develop an efficient transient model for accurately predicting the battery cell temperature in different types of parallel air-cooled BTMSs. A flow resistance network model for BTMS with I-type flow is established according to law of momentum conservation. Based on energy equations, a transient heat transfer model is derived to calculate the temperature distribution of battery pack in the BTMSs. The model results are in good agreement with experimental data, verifying the effectiveness and efficiency of this model. The deviations of T max and Δ T max between the models and experiment are less than 1.5 K. Furthermore, by using the developed transient models, the deviations of T max and Δ T max respectively decrease by 70% and 26%, in comparison with previous study. Finally, based on the developed models, the widths of parallel channels and divergence/convergence ducts in the BTMSs are designed, leading to remarkably enhanced cooling performance. The present study provides an efficient transient heat transfer model for parallel cooling systems, which can provide a deeper insight into the system performance and be applied to structural optimization of the systems. • A flow resistance network model for BTMS with I-type flow is developed.. • A transient heat transfer model for parallel BTMSs is derived mathematically. • Experiments are conducted to verify the developed transient heat transfer model. • The optimized BTMSs based on the developed models achieve good performance. [ABSTRACT FROM AUTHOR]

• The heat generation and transfer modeling approaches of LIB are introduced. • The advantages and disadvantages on various multi-physical BTMS are summarized. • The emerging techniques in emergency battery thermal barrier are examined. • A novel BTMS framework is proposed based on CHAIN. New energy vehicles have significant prospects in reducing greenhouse gas emission and environmental pollution. Lithium-ion batteries are the favored power source in electric vehicles because of their high energy density and long service life. The battery performance depends noticeably on the temperature. Battery thermal management system, which can keep the battery pack working in a proper temperature range, not only affects significantly the battery pack system performance but is also vital for the safety and stability. This article mainly summarizes the thermal management models in the literature which can predict heat generation, heat transfer and the temperature distribution within the battery cell, module and pack. The multi-physical battery thermal management systems are divided into three categories based on different methods of cooling the phase change materials such as air-cooled system, liquid-cooled system, and heat-pipe-cooled system. The emergency battery thermal battier methods are also summarized in multi-scale included material scale, battery management system and supplementary system. Finally, we propose a novel digital solution for full-lifespan thermal management control of EV power system based on CHAIN framework that helps improve the power battery temperature control strategy applying multiple working conditions. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The temperature control technology based on phase change material (PCM) demonstrates excellent performance in the field of battery thermal management. However, the compact and bulky structure of the traditional composite PCM (CPCM) module reduces the energy density of the battery pack greatly, and is unfavorable to the secondary heat dissipation. In this work, we develop a novel PCM cooling structure by substituting the common block-shaped CPCM (B-CPCM) module with serpentine CPCM (S-CPCM) plates. The S-CPCM plates with high shape stability provide a much larger surface area and many air flow channels in comparison to the B-CPCM module, thus endowing the module with outstanding secondary heat dissipation capability. For example, under the same fan power of forced air convection (5.2 W), the S-CPCM module delivers a much lower maximum temperature than the B-CPCM module (51.9 vs. 54.2 °C) during the repeated charge-discharge process. As highlighted here, on the basis of guaranteeing the cooling performance, the S-CPCM cooling structure also saves ~70% of the CPCM amount, and thereby the energy density of the battery module is increased by 13.8 Wh kg−1. Image 1 • Novel serpentine composite phase change material (S-CPCM) plates are designed. • The S-CPCM cooling structure saves 70% of the CPCM amount in the battery module. • The energy density of the module with S-CPCM cooling is increased by 13.8 Wh kg−1 • S-CPCM plates provide air flow channels and large surface area for heat dissipation. • The S-CPCM cooling structure shows much enhanced heat dissipation performance. [ABSTRACT FROM AUTHOR]