Enhancement of the Thermal Energy Storage Using Heat-Pipe-Assisted Phase Change Material

Usage of phase change materials' (PCMs) latent heat has been investigated as a promising method for thermal energy storage applications. However, one of the most common disadvantages of using latent heat thermal energy storage (LHTES) is the low thermal conductivity of PCMs. This issue affects the rate of energy storage (charging/discharging) in PCMs. Many researchers have proposed different methods to cope with this problem in thermal energy storage. In this paper, a tubular heat pipe as a super heat conductor to increase the charging/discharging rate was investigated. The temperature of PCM, liquid fraction observations, and charging and discharging rates are reported. Heat pipe effectiveness was defined and used to quantify the relative performance of heat pipe-assisted PCM storage systems. Both experimental and numerical investigations were performed to determine the efficiency of the system in thermal storage enhancement. The proposed system in the charging/discharging process significantly improved the energy transfer between a water bath and the PCM in the working temperature range of 50 & DEG;C to 70 & DEG;C

Experimental and Numerical Study on Heat Pipe Assisted PCM Storage System

In this study, thermal performance, energy storage and cooling capacity of a heat pipe assisted Phase Change Material (PCM) storage system have been investigated experimentally andnumerically. The heat pipe assisted PCM storage system can store and release energy efficiently.Heat pipe as a two-phase heat transfer device with very high thermal conductivity can beemployed to transfer heat at a high rate and very low-temperature difference. The core ideareferred to this system is to improve the capability of storing and releasing energy at PCMstorage system by using heat pipe. In order to study the effect of using heat pipe on energy storage system performance andminiature cooling applications, two different test rigs were built to investigate melting andsolidification processes. In addition, a numerical analysis of a heat pipe assisted PCM storagesystem has been performed. The two systems were modeled using Gambit and Fluent softwareand validated by experimental results. Results of case I indicate that it is beneficial for the energy storage system to use heat pipe toincrease the heat transfer rate significantly. In other words, the charging and discharging (heat absorption/release) of the storage system can happen faster with a higher power. Considering the case II, which is designed for the miniature cooling applications, it is found thatthe system can contribute to cooling process up to 86.7%. Keywords: heat pipe; phase change materials; heat transfer; melting and solidificatio

A New Concept of Air Cooling and Heat Pipe for Electric Vehicles in Fast Discharging

This paper presents the concept of a hybrid thermal management system (TMS) including natural convection, heat pipe, and air cooling assisted heat pipe (ACAH) for electric vehicles. Experimental and numerical tests are described to predict the thermal behavior of a lithium titanate oxide (LTO) battery cell in a fast discharging process (8C rate). Specifications of different cooling techniques are deliberated and compared. The mathematical models are solved by COMSOL Multiphysics® (Stockholm, Sweden), the commercial computational fluid dynamics (CFD) software. The simulation results are validated against experimental data with an acceptable error range. The results specify that the maximum cell temperatures for the cooling systems of natural convection, heat pipe, and ACAH reach 56, 46.3, and 38.3 °C, respectively. We found that the maximum cell temperature experiences a 17.3% and 31% reduction with the heat pipe and ACAH, respectively, compared with natural convection

Experimental and Numerical Study on Heat Pipe Assisted PCM Storage System

In this study, thermal performance, energy storage and cooling capacity of a heat pipe assisted Phase Change Material (PCM) storage system have been investigated experimentally andnumerically. The heat pipe assisted PCM storage system can store and release energy efficiently.Heat pipe as a two-phase heat transfer device with very high thermal conductivity can beemployed to transfer heat at a high rate and very low-temperature difference. The core ideareferred to this system is to improve the capability of storing and releasing energy at PCMstorage system by using heat pipe. In order to study the effect of using heat pipe on energy storage system performance andminiature cooling applications, two different test rigs were built to investigate melting andsolidification processes. In addition, a numerical analysis of a heat pipe assisted PCM storagesystem has been performed. The two systems were modeled using Gambit and Fluent softwareand validated by experimental results. Results of case I indicate that it is beneficial for the energy storage system to use heat pipe toincrease the heat transfer rate significantly. In other words, the charging and discharging (heat absorption/release) of the storage system can happen faster with a higher power. Considering the case II, which is designed for the miniature cooling applications, it is found thatthe system can contribute to cooling process up to 86.7%. Keywords: heat pipe; phase change materials; heat transfer; melting and solidificatio

Advanced Thermal Management Systems for High-Power Lithium-Ion Capacitors: A Comprehensive Review

The acceleration demand from the driver in electric vehicles (EVs) should be supported by high-power energy storage systems (ESSs). In order to satisfy the driver’s request, the employed ESS should have high power densities. On the other hand, high energy densities are required at the same time for EVs’ traction to minimize the range anxiety. In this context, a novel ESS has emerged that can provide high power and energy densities at the same time. Such technology is called lithium-ion capacitor (LiC), which employs Li-doped carbon as negative electrode and activated carbon as positive electrode. However, high heat generation in high current applications is an issue that should be managed to extend the LiCs life span. Hence, a proper thermal management system (TMS) is mandatory for such a hybrid technology. Since this ESS is novel, there are only several TMSs addressed for LiCs. In this review article, a literature study regarding the developed TMSs for LiCs is presented. Since LiCs use Li-doped carbon in their negative electrodes, lithium-titanate oxide (LTO) batteries are the most similar lithium-ion batteries (LiBs) to LiCs. Therefore, the proposed TMSs for lithium-ion batteries, especially LTO batteries, have been explained as well. The investigated TMSs are active, passive, and hybrid cooling methods The proposed TMSs have been classified in three different sections, including active methods, passive methods, and hybrid methods

An Experimental Study on Thermal Performance of Graphite-Based Phase-Change Materials for High-Power Batteries

High-power lithium-ion capacitors (LiC) are hybrid energy storage systems (EES) with the combined benefits of lithium-ion batteries (LiB) and supercapacitors, such as high specific energy, high specific power, and a long lifetime. Such advanced technology can be used in high-power applications when high charging and discharging are demanded. Nevertheless, their performance and lifetime highly depend on temperature. In this context, this paper presents an optimal passive thermal management system (TMS) employing phase-change materials (PCM) combined with graphite to maintain the LiC maximum temperature. To evaluate the thermal response of the PCM and the PCM/G, experimental tests have been performed. The results exhibit that when the cell is under natural convection, the maximum temperature exceeds 55 °C, which is very harmful for the cell’s lifetime. Using the pure paraffin PCM, the maximum temperature of the LiC was reduced from 55.3 °C to 40.2 °C, which shows a 27.3% temperature reduction compared to natural convection. Using the PCM/G composite, the maximum temperature was reduced from 55.3 °C (natural convection) to 38.5 °C, a 30.4% temperature reduction compared to natural convection. The main reason for this temperature reduction is the PCM’s high latent heat fusion, as well as the graphite thermal conductivity. Moreover, different PCM/G thicknesses were investigated for which the maximum temperature of the LiC reached 38.02 °C, 38.57 °C, 41.18 °C, 43.61 °C, and 46.98 °C for the thicknesses of 15 mm, 10 mm, 7 mm, 5 mm, and 2 mm, respectively. In this context, a thickness of 10 mm is the optimum thickness to reduce the cost, weight, volume, and temperature

Equivalent Circuit Model for High-Power Lithium-Ion Batteries under High Current Rates, Wide Temperature Range, and Various State of Charges

The most employed technique to mimic the behavior of lithium-ion cells to monitor and control them is the equivalent circuit model (ECM). This modeling tool should be precise enough to ensure the system’s reliability. Two significant parameters that affect the accuracy of the ECM are the applied current rate and operating temperature. Without a thorough understating of the influence of these parameters on the ECM, parameter estimation should be carried out manually within the calibration, which is not favorable. In this work, an enhanced ECM was developed for high-power lithium-ion capacitors (LiC) for a wide temperature range from the freezing temperature of −30 °C to the hot temperature of +60 °C with the applied rates from 10 A to 500 A. In this context, experimental tests were carried out to mimic the behavior of the LiC by modeling an ECM with two RC branches. In these branches, two resistance and capacitance (RC) are required to maintain the precision of the model. The validation results proved that the semi-empirical second-order ECM can estimate the electrical and thermal parameters of the LiC with high accuracy. In this context, when the current rate was less than 150 A, the error of the developed ECM was lower than 3%. Additionally, when the demanded power was high, in current rates above 150 A, the simulation error was lower than 5%

A Comprehensive Review of Lithium-Ion Capacitor Technology: Theory, Development, Modeling, Thermal Management Systems, and Applications

This review paper aims to provide the background and literature review of a hybrid energy storage system (ESS) called a lithium-ion capacitor (LiC). Since the LiC structure is formed based on the anode of lithium-ion batteries (LiB) and cathode of electric double-layer capacitors (EDLCs), a short overview of LiBs and EDLCs is presented following the motivation of hybrid ESSs. Then, the used materials in LiC technology are elaborated. Later, a discussion regarding the current knowledge and recent development related to electro-thermal and lifetime modeling for the LiCs is given. As the performance and lifetime of LiCs highly depends on the operating temperature, heat transfer modeling and heat generation mechanisms of the LiC technology have been introduced, and the published papers considering the thermal management of LiCs have been listed and discussed. In the last section, the applications of LiCs have been elaborated

An Enhanced Phase Change Material Composite for Electrical Vehicle Thermal Management

Lithium-ion (Li-ion) battery cells are influenced by high energy, reliability, and robustness. However, they produce a noticeable amount of heat during the charging and discharging process. This paper presents an optimal thermal management system (TMS) using a phase change material (PCM) and PCM-graphite for a cylindrical Li-ion battery module. The experimental results show that the maximum temperature of the module under natural convection, PCM, and PCM-graphite cooling methods reached 64.38, 40.4, and 39 °C, respectively. It was found that the temperature of the module using PCM and PCM-graphite reduced by 38% and 40%, respectively. The temperature uniformity increased by 60% and 96% using the PCM and PCM-graphite. Moreover, some numerical simulations were solved using COMSOL Multiphysics® for the battery module

A comprehensive review of novel cooling techniques and heat transfer coolant mediums investigated for battery thermal management systems in electric vehicles

In electric vehicles (EVs), battery thermal management system (BTMS) plays an essential role in keeping the battery working within the optimal operating temperature range and preventing thermal runaway. Many cooling mediums have been conducted into BTMS to transfer, absorb, or dissipate the heat generated from the batteries. Thermal conductivity, heat transfer coefficient, cooling performance, cost, poison, environment, system size, and equipment needed are critical factors in choosing the ideal heat transfer coolant for the BTMS. This review paper concentrates on the novel and echo-friendly heat transfer coolant mediums investigated for BTMS and has been rarely documented in the literature. In the scope of this review, traditional BTMS coolant mediums including air, water, phase change material (PCM), and hybrid coolants are considered, and their optimization techniques have been discussed. Additionally, a comprehensive review is provided on novel techniques and novel materials that have the possibility of enhancing the thermal performance of the battery pack on the one hand, as well as the potential of integration into BTMS with higher safety and less (weight, volume, cost, toxicity, and power consumption) compared to the classical heat transfer coolant mediums on the other hand. Finally, evaporative, mist, spray, and nanofluid techniques are found as promising cooling techniques. In terms of environmental, availability, and non-toxicity aspect, jute has the highest possibility of being integrated into BTMS. This study will give the opportunity to see the latest research investigating novel cooling mediums, which will lead to further improvement for BTMS