The integration of a phase change material (PCM) with a metal hydride (MH) reactor has received considerable attention recently. In such a system, the exothermic and endothermic processes of the MH ...reactor can be utilized effectively by enhancing the thermal exchange between the MH reactor and the PCM bed. In this study, a novel design that integrates the MH reactor with cascaded PCM beds is proposed. Magnesium nickel (Mg2Ni) alloy is used as the hydride reactor. Two different types of PCMs with different melting temperatures and enthalpies are arranged in series. A parametric study is carried out to identify the optimum distribution of the different PCMs. The results indicate that the proposed cascaded MH-PCM sandwich design improves the heat transfer rate which consequently shortens the time duration of the hydrogenation and dehydrogenation processes by 26% and 51%, respectively, compared to an MH-PCM sandwich design that includes only a single PCM.
Display omitted
•A new design of a metal hydride reactor equipped with cascaded PCMs was proposed.•Cyclic behaviors of the new design were investigated.•The effect of the PCMs' storage capacity distribution in the new design was studied.•The hydrogenation/dehydrogenation times were reduced by 26% and 51%, respectively.
Display omitted
•CNC was employed as Pickering emulsifier due to excellent emulsifying ability.•PCM microcapsule with MF shell was prepared via Pickering emulsion polymerization.•The core material ...content of PW microcapsules is as high as 87%.•PCM microcapsules possess a retention rate of 99.7% after 200 heating–cooling scans.•PCM microcapsules with MF shell are self-extinguishing and flame-retardant.
Thermal energy storage technology based on phase change materials (PCMs) is promising for temperature regulation and thermal energy storage. However, the applications of organic PCMs are hindered from their leakage issue. Encapsulating PCMs in microcapsules with polymer shell could effectively prevent the leakage of PCMs and enhance heat conduction. Herein, PCM microcapsules with melamine–formaldehyde resin (MF) as shell were prepared via cellulose nanocrystal (CNC) stabilized Pickering emulsion in-situ polymerization. CNCs were chosen as emulsifiers of Pickering emulsion and reinforcing nanofillers of MF shell due to their outstanding emulsifying ability, mechanical strength, and sustainability. Paraffin wax (PW) and n-octadecane (C18) were employed as PCMs, respectively. The prepared PCM microcapsules are in diameter of 4 μm with a tunable thickness of MF shell. The phase change enthalpy of PW and C18 microcapsules are as high as 164.8 and 185.1 J/g, corresponding to PCM core material content of 87.0 and 84.3%, respectively. PCM microcapsules are stable below 200 ℃ and display a retention rate of the phase change enthalpy reach up to 99.7% after 200 cycles of heating–cooling. Moreover, the PCM microcapsules are self-extinguishing due to the flame-retardant properties of MF shell. The promising applications of PCM microcapsules in the field of temperature regulation were also demonstrated.
Display omitted
•Locally enhanced heat transfer for power battery module was presented.•A novel CPCM was prepared by loading graphene, carbon tube and expanded graphite into paraffin.•The locally ...enhanced heat transfer effect of the CPCM was almost the same as copper foam/PCM.•Temperature of the battery module was more uniform when the enhanced region was narrowed.
The rapid development of new energy vehicles urgently requires lightweight power battery modules with excellent thermal performance. To achieve this goal, a high thermal conductivity composite phase change materials (CPCM) was prepared and its locally enhanced heat transfer characteristics of power battery module were experimentally studied. The results showed that CPCM had almost the same localized heat transfer effect as copper foam/PCM under different thermal environment. Furthermore, locally enhanced heat transfer characteristics have been comparatively studied for center regions with different sizes in the power battery module using the CPCM as cooling media. The results showed that when 4 batteries were enhanced using CPCM, the maximum temperature in a 36-battery module during the 3C discharge was limited to 44.6 °C while the maximum temperature difference was limited to 0.8 °C. Interestingly, the results revealed that the maximum temperature of battery module was slightly increased (less than 1%) but the temperature difference was reduced by 46.7% compared with enhancement for 16 batteries, which was helpful to improve the temperature consistency of the battery module.
•A spherical PCM capsule with circular pin-fins is proposed and investigated.•The cold charging time is reduced by more than 50% with six pin-fins.•The influence of fin length and diameter is studied ...and the optimal value is presented.•The fin effectiveness exceeds 2.0 at the cost of approximately 1% of PCM filling ratio.
A spherical phase change material (PCM) capsule with circular pin-fins for latent cold thermal energy storage is proposed and studied in this paper. Experiments were conducted to monitor the PCM temperature variation in each capsule during solidification in order to validate the simulated results calculated based on the enthalpy method. Good agreement was found between the simulated values and experimental data and the deviations were lesser than 6.9%. Thermal performances, including the temperature variation, liquid fraction distribution as well as cold charging rate, of the capsules with various pin-fin configurations were numerically compared. Results demonstrate that the cold charging rate is improved dramatically due to the insertion of fins, and the cold charging time is decreased by more than 50% in the capsule with six fins (approximately 3600 s) compared to that without fins (approximately 7700 s). In addition, the increasing extent is positively related to the pin-fin number, despite the slight reduction of PCM filling ratio. Furthermore, it is indicated that the thermal performance can also be improved by means of optimizing geometric parameters of pin-fins, such as their length L and diameter D. As for the spherical capsule with an inner radius of R = 20 mm, the optimal parameter is regarded to be L/R = 75% and D = 2 mm.
Display omitted
•A pipeless shape-stabled phase change material (SSPCM) channel was proposed.•Cooling system of SSPCM and metal channel were compared.•Phase change emulsion (PCE) was innovatively ...integrated with SSPCM channel.•Cooling system of PCE/SSPCM channel and water/SSPCM channel were compared.•Key factors were analyzed based on orthogonal simulation.
With the improvement of electric vehicle technology and requirements, power battery thermal management systems should not only have excellent temperature control ability but also meet the development requirements of compactness and lightweight. To achieve this goal, a pipeless cooling system coupled with shape-stabilized phase change material (SSPCM) channel and phase change emulsion (PCE) was proposed. In this study, the thermal performance of cooling systems based on metal channel and SSPCM channel were compared, and the thermal properties of the PCE/SSPCM channel system and the Water/SSPCM channel system were compared. Based on the above, the key factors affecting the PCE/SSPCM channel battery thermal management system were analyzed. Finally, the effects of these factors were studied together by an orthogonal simulation. The results show that the maximum temperature and the maximum temperature difference of the SSPCM channel system were 16.8 °C and 3.3 °C lower than the metal channel system, respectively. And the PCE/SSPCM channel system surpasses the Water/SSPCM channel system when the PCE undergoes phase change at low inlet velocity. The orthogonal simulation results show that under the optimal parameters, the battery thermal management system can maintain the temperature and temperature difference of the battery module below 54.8 °C and 4.8 °C in 7 C charge–discharge cycles, which can meet the thermal management requirement of power battery under high-rate charge and discharge.
Display omitted
•Experiments conducted on a simple heat sink and heat sink with PCM and nano-PCM.•The system performance is investigated under active, passive, and intermittent usage.•Image ...processing is performed to study the PCM melting/solidification process.•Nano-PCM showed better performance compare to PCM in the case of free convection.•Adding nanoparticles enhanced the solidification rate of PCM.
This paper presents experimental investigation for the effects of a phase change material (PCM) and a nano/phase change material (nano-PCM) on the thermal performance of an electronic chipset. A thermal storage system using Paraffin wax as a PCM is integrated with a heat sink. Additionally, the PCM is modified as nano-PCM by mixing it with multiwall carbon nanotubes (MWCNTs). The effects of various quantities of the PCM, concentrations of the MWCNTs in the PCM, and different power levels on three different modules of heat sinks (without PCM, filled with PCM, and filled with nano-PCM) are studied in passive and active operating modes. Experiments are also performed when the heat flux is applied intermittently, which commonly encountered in the thermal management of portable electronic devices. The phase front propagation is captured and analyzed by an image processing technique. It is found that the PCM can significantly increase the usage time of the system and the nano-PCM as compared to the PCM can extend this time under passive cooling condition. Under active cooling condition, the usage of PCM and nano-PCM may increase the steady-state temperature; however, it reduces the operating temperature of the chipset at the beginning period of the operating time. The nano-PCM module can enhance thermal management of the system by reducing the cooling time up to 6% as compared to the PCM. Under intermittent heating, using more on-and-off cycles lead to decreasing the chipset peak temperature. Using PCM and nano-PCM increases the operating time and reduces the peak temperature of the chipset under intermittent use.
Power efficiency of Photovoltaic (PV) cell reduce due to the warm up under solar irradiation. Several passive and active cooling experimental investigations are implemented on a PV cell in this study ...to find out their impacts on the electrical and thermal performance of a PVT system. All experiments are performed in a solar simulator under a wide range (regular-concentrated) of solar radiation power (800–1700 W m−2). PCM is used as passive coolant system, whereas to overcome the malfunction of PCM, due its low thermal conductivity, PCM is infiltered in a special heat conductive foam (PS-CNT foam). Results revealed that PCM-composite can diminish the PV-cell temperature up to 6.8% and increase electrical effciciency up to 14.%. Separately, active cooling are examined by passing water with the range of 0.3–1 lit.min−1 through a cooling block mounted undre the PVT system. In the active cooling system, due to the efficient electrical power generation as well as harvesting thermal energy, the system performance is much higher than passive PVT systems. The best PVT system examined in this study is the PV-PCM-composite system which its energy efficiencies in the active cooling is 66.8–82.6%.
Display omitted
•Various passive and active cooling PVT systems are investigated, experimentally.•Wide range (regular-concentrated) of solar radiation power (800–1700 W m−2) on PVT is implemented.•PCM is infilterd in a special heat conductive foam (PS-CNT foam), as PCM-composite.•PCM-composite can diminish the PV-cell temperature up to 6.8% and increase electrical effciciency up to 14.%.•Energy efficiencies of the best PVT examined in this investigation in passive and active cooling are 13–14.2% and 66.8–82.6%.
•Myristic acid–palmitic acid eutectic was microencapsulated with silica shell.•Structure, morphology of microencapsulated phase change material were investigated.•Thermal capacity, stability of ...microencapsulated phase change material were analyzed.•Silica shell improved thermal stability of microencapsulated phase change material.
In this work microencapsulation of myristic acid–palmitic acid (MA–PA) eutectic mixture with silica shell using sol−gel method has been attempted. The core phase change material (PCM) for thermal energy storage was myristic acid−palmitic acid eutectic mixture and the shell material to prevent the PCM core from leakage was silica prepared from methyl triethoxysilane (MTES). Thermal properties of the microcapsules were measured by differential scanning calorimeter (DSC). The morphology and particle size of the microcapsules were examined by scanning electronic microscope (SEM). Fourier transformation infrared spectrophotometer (FT–IR) and X–ray diffractometer (XRD) were used to investigate the chemical structure and crystalloid phase of the microcapsules respectively. The DSC results indicated that microencapsulated phase change material (MPCM) melts at 46.08°C with a latent heat of 169.69kJkg−1 and solidifies at 44.35°C with a latent heat of 159.59kJkg−1. The thermal stability of the microcapsules was analyzed by a thermogravimeter (TGA). The results indicated that the MPCM has good thermal stability and is suitable for thermal energy storage application.
Display omitted
•The single battery model is representative of the battery module at large flow rate.•Characteristic melting stages are identified for novel conjugated cooling of battery ...module.•Conjugated cooling can significantly reduce the battery temperature and ramp-up rate.•Increasing thermal column size or heat spreading plate thickness improves heat dissipation significantly.•Good agreement is found between numerical analysis and experimental test.
A novel conjugated cooling configuration using phase change material (PCM) and liquid cooling techniques is proposed, and its thermal performance is investigated for a battery module. 106 cylindrical batteries are connected to the cold plate at the bottom through a heat spreading plate and the adjacent thermal columns, with PCM filled in between the gaps, which forms the cooling configuration. Three-dimensional numerical models are established for the cooling of the representative battery and battery module, which includes the battery connected to a liquid cooled mini-channel cold plate through the heat spreading plate and thermal column structures. The thermal characteristics of the battery incorporating the PCM melting and liquid cooling are examined at large flow rate. The geometrical parameters such as the size of the thermal column, the thickness of the heat spreading plate and the spacing of the batteries are investigated for the present conjugated cooling configuration. Both the battery temperature ramp-up rate and the steady-state battery temperature are significantly reduced by the conjugated cooling, in comparison with single PCM or liquid cooling conditions. The effects of various structure parameters on the thermal performance can be visualized by plotting the working time t50 vs the heat density based on the PCM volume. A comparison of the numerical simulation with the preliminary experiment work shows good agreement. This work can be useful in the design of conjugated configurations for the battery thermal management.
•PCM with heat sink extends the maximum operation time resulting a lower base temperature.•A 3mm thick pin-fin heat sink ensures the elongation in latent heat phase (LHP).•Maximum completion of LHP ...duration was found 141min at 2.0kW/m2 for 3mm pin-fin heat sink.•The enhancement ratio of 4.78 against 2.0kW/m2 heat density waw found for 3mm pin-fin heat sink.
Efficient thermal management (TM) based on phase change material (PCM) is adopted for the cooling of portable electronic devices. PCM namely n-eicosane is employed to absorb thermal energy released by such electronics. Four different configurations of circular pin-fin heat sinks with fin thickness of 2mm, 3mm and 4mm including a no fin heat sink (used as a reference heat sink) were adopted. Pin-fins were made of aluminum due to light weight and good thermal conductivity to act as a thermal conductivity enhancers (TCEs). Pin-fin heat sinks of constant (9%) volume fraction of TCE are filled with four volumetric fractions of PCM to explore the best amount of PCM volume. A wide range of heat flux is provided at the heat sink base and the effect of fin configuration, PCM volume, latent heat phase, power densities, thermal capacity and thermal conductance are reported in this study. Three different critical set point temperatures (SPTs) are selected for this investigation. Enhancement ratios are reported against various PCM fractions to illustrate the thermal performance for passive cooling. The results show that 3mm fin thickness heat sink has best enhancement in operation for TM module controlling temperature of electronic devices.
