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Batteries, particularly lithium‐ion batteries, are sensitive to temperature changes. Battery thermal management systems (BTMS) are essential in various battery‐powered applications, especially electric vehicles (EVs) and portable electronic devices. This study examines the importance of phase change material (PCM) in battery packs using numerical analysis. An examination is conducted on a battery pack consisting of 18 650 battery cells arranged in a 5 × 5 configuration. A comparative analysis is performed to evaluate the thermal efficiency of the battery pack with and without PCM. The study examines the influence of ambient conditions and charging rates on the selection of PCM for battery packs. A hybrid cooling solution utilizing PCM and a water tube has also been investigated against conventional passive PCM‐based BTMS. Additionally, two types of fins, namely circular and spiral fins, are introduced to improve the heat transfer rate. PCM‐based cooling systems are most effective when the ambient temperature is below the melting temperature of the PCM. However, when the ambient temperature exceeds the melting temperature of the PCM, this cooling system outperforms conventional PCM‐based cooling. The maximum temperature is found as 319, 316.9, and 315.3 K using without fin, circular fin and spriral fina, respectively. The spiral fins are found more effective than circular fins under high ambient temperature. In conclusion, The PCM‐with spiral‐fin system demonstrates notable benefits in high‐temperature environments. [ABSTRACT FROM AUTHOR]

The charging and discharging rates of a phase change material (PCM) in a horizontal latent heat storage unit (LHSU) is largely influenced by the lower thermal conductivity of the PCM. In the present research, four different configurations of longitudinal fins are proposed to augment the heat transfer in horizontal shell and tube type LHSUs. Numerical investigations are reported to establish the thermal performance augmentation with rectangular, triangular, and Y‐shaped (bifurcated) fins. From the results, it has been inferred that all fin configurations provide a faster charging and discharging rate. In the present set of geometric dimensions of LHSU considered, a reduction in charging time of 68.71% is evaluated for case III (three rectangular fins with one fin positioned in the area of the heat transfer fluid [HTF] surface) and case V (two bifurcated fins with one fin positioned in the area of the HTF surface). Moreover, overall cycle (charging + discharging) time is reduced by 58.3% for case III. Employment of fins results in a faster rate of absorption and extraction of energy from the PCM. [ABSTRACT FROM AUTHOR]

• Performance of sinusoidal wavy and elliptical curved rectangular winglet vortex generators (RWVGs) are established. • The temperature and flow fields were presented and analyzed. • The effect of up and down configuration of VGs was evaluated. • The best performance can be achieved with the curved down type RWVGs. Vortex generation has emerged as a promising passive method for enhancing air-side heat transfer. In the present work, two-dimensional numerical analysis is carried out to examine the thermo-fluid analysis of fin-and-tube compact heat exchangers with sinusoidal wavy and elliptical curved type rectangular winglet vortex generator (RWVG) having varying Reynolds number ranges from 400 to 1000. The wavy and curved VGs are also placed as up and down configurations with respect to flow direction. Thus the effect of the different common flow down (CFD) configurations of wavy-up, wavy-down, curved-up, curved-down and flat rectangular winglet is compared with baseline configuration (non-winglet case) for flow structure, temperature distribution and pressure distribution for fin-and-tube compact heat exchanger with seven inline circular tube arrangement. They are also compared with thermo-hydraulic performance criterions which include Nusselt number (Nu), Pressure drop (ΔP), friction factor (f), London area goodness factor (j / f). Appreciable improvement in heat transfer characteristics is observed with wavy and curved rectangular winglet with a moderate loss in pressure. Compared with the non-winglet baseline and flat RWVG case, the heat transfer performance of the fin-and-tube heat exchanger is significantly improved with wavy-up and down and curved-up and down configurations. Further, it is also noted that up-wavy RWVG showed the best heat transfer improvement compared to any other RWVG configuration considered. However, Wavy-up configuration has the lowest values of j / f than others and curved-down has higher values of j / f than others. Thus, curved-down RWVG found suitable than other cases of RWVG as far as London goodness factor strategy. [ABSTRACT FROM AUTHOR]

In the present study, experimental and analytical thermal performance of automobile radiator using nanofluids is investigated and compared with performance obtained with conventional coolants. Effect of operating parameters and nanoparticle concentration on heat transfer rate are studied for water as well as CuO/EG‐water based nanofluid analytically. The results are presented in the form of graphs showing variations of net heat transfer rate for various coolant flow rate, air velocity, and source temperature for various CuO/EG‐water based nanofluids. Experimental results indicate that with the increase in coolant flow rate and air velocity, heat transfer rate increases, reaches maximum and then decreases. Experimental investigation of a radiator is carried out using CuO/EG‐water based nanofluids. Results obtained by experimental work and analytical MATLAB code are almost the same. Maximum absolute error in water and air side is within 12% for all flow condition and coolant fluids. Nusselt number of nanofluid is calculated using equation number 33[9]. The results obtained from experimental work using 0.2% volume CuO/EG‐water based nanofluids are compared with the results obtained from MATLAB code. The results show that the maximum error in the outlet temperature of the coolant and air is 12% in each case. Thus MATLAB code can be used for different concentration of nanofluids to study the effect of operating parameters on heat transfer rate. Thus MATLAB code developed is valid for given heat exchanger applications. From the results obtained by already validated MATLAB code, it is concluded that increase in coolant flow rate, air velocity, and source temperature increases the heat transfer rate. Addition of nanoparticles in the base fluid increases the heat transfer rate for all kind of base fluids. Among all the nanofluid analyzed in this study, water‐based nanofluid gives highest value of heat transfer rate and is recommended for the heat exchanger applications under normal operating conditions. Maximum enhancement is observed for ethylene glycol‐water (4:6) mixture for 1% volume concentration of CuO is almost equal to 20%. As heat transfer rate increases with the use of nanofluids, the heat transfer area of the radiator can be minimized. [ABSTRACT FROM AUTHOR]

Employment of latent heat storage unit (LHSU) utilizing phase change material (PCM) in a substantial scale is constrained by the poor thermal conductivity of PCMs. Future utilization of LHSU will therefore to a great extent rely on the heat transfer intensification techniques. Present research is on enhancement techniques in which heat transfer mechanism is altered without altering the mass of PCM and heat transfer surface area. The intensification mechanisms considered in the present research include imparting eccentricity to heat transfer fluid (HTF) pipe, imparting rotation to the LHSU and providing multi HTF tube. Numerical investigations are reported here towards comparative evaluation of the thermal characteristics associated with such intensification mechanisms for horizontal LHSU. In the present study stearic acid (melting point 55.7–56.6 °C) is used as PCM and water is used as HTF. Results infer that all the three mechanisms offer quicker melting rate. For the geometric configuration of LHSU considered in the present research, a reduction in melting time of 47.75% is evaluated for rotating LHSU. The rate of energy storage is higher for both eccentric and rotating LHSU. Solidification process is however not accelerated by such techniques. On the contrary, eccentric and multi HTF tube LHSU takes more time for solidification. [ABSTRACT FROM AUTHOR]

An experimental analysis is presented to establish the thermal performance of a latent heat thermal storage ( LHTS) unit. Paraffin is used as the phase change material ( PCM) on the shell side of the shell and tube-type LHTS unit while water is used as the heat transfer fluid ( HTF) flowing through the inner tube. The fluid inlet temperature and the mass flow rate of HTF are varied and the temperature distribution of paraffin in the shell side is measured along the radial and axial direction during melting and solidification process. The total melting time is established for different mass flow rates and fluid inlet temperature of HTF. The motion of the solid-liquid interface of the PCM with time along axial and radial direction of the test unit is critically evaluated. The experimental results indicate that the melting front moves from top to bottom along the axial direction while the solidification front moves only in the radial direction. The total melting time of PCM increases as the mass flow rate and inlet temperature of HTF decreases. A correlation is proposed for the dimensionless melting time in terms of Reynolds number and Stefan number of HTF. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (). DOI 10.1002/htj.21120 [ABSTRACT FROM AUTHOR]

• Thermo-hydraulic performance of an FTHE system with and without modified RWVGs was investigated experimentally • RWVGs with and without a circular punched hole were compared critically. • RWVG with punched hole offers low thermal flow resistance than RWVG-Flat. • RWVG with punched hole performs better than RWVG-Flat cases in terms of thermal performance factor. • Correlations were established and proposed to predict Nusselt number (Nu) and friction factor (f). The presence of vortices in a flow field significantly impacts heat transmission. The effect of a modified rectangular winglet vortex generator on heat transfer and pressure drop performance for a fin-tube heat exchanger (FTHE) is experimentally explored in this work. Design and fabrication of full-scale prototype of an FTHE are carried out. Two types of rectangular winglet vortex generators (RWVGs), i.e., Flat RWVG and RWVG with a circular punched hole are installed into the FTHE for experimentation purposes. The experimental studies are conducted with Reynolds numbers ranging from 8000 to 25,000. The experimental results show that the use of RWVG in FTHE provided a much greater heat transfer coefficient than FTHE without RWVGs with an increase in pressure loss penalty. For better wake management, the RWVG are installed behind the circular tubes in a common flow down (CFD) arrangement. The comparative study is carried out to explore thermo-fluid performance of fin-and-tube heat exchanger with two inline circular tube arrangements for all considered cases of RWVGs. By varying the tube wall temperature (i.e., 65, 75, and 85 °C), thermo-hydraulic performance criteria such as Nusselt number (Nu), friction factor (f), and thermal performance factor (η) are compared. Lower tube surface temperature gave the highest enhancement in heat transfer performance with a lower friction factor. However, the thermal performance factor (η) for the RWVG with a circular punched hole is about 1.04–3.2%, 1.3–5.4% and 2.3–10.52% higher than RWVG-Flat for the tube wall temperature 65 °C, 75 °C, and 85 °C, respectively. [ABSTRACT FROM AUTHOR]

The aim of this study is to augment thermal transport in phase change materials (PCM) by an optimum installation of the fins. The study emphasizes to obtain best size and location of the fins to minimize the total melting time for the given fins to PCM volume ratio. Thus, the fins are resized and re-positioned according to the constructal theory. The fundamental principle of the theory is to configure limited numbers of fins at optimal position, where thermal transport potential is maximum. A numerical code based on conjugate heat transfer coupled enthalpy porosity approached is developed. The numerical results show that the reduction in size of fins at low temperature gradient and re-positioning them at high temperature gradient are found to be advantageous. In the present study, the fin to PCM volume is reduced by half based on the constructal theory. The proposed constructal fin design augments thermal performance by 4.38% than conventional configuration. The reduction in fins volume by half has not only increased thermal energy storage, but also decreased fins solid mass that can help to reduce the overall weight of thermal energy storage systems. It is also concluded that the fins should not be placed much near to the bottom surface to gain uniform thermal penetration throughout the enclosure. • A numerical code using conjugate heat transfer coupled enthalpy porosity approach is developed. • The fins size and location is augmented to enhance the conduction transfer. • The fin design using constructal theory addressed the deficiency of slow melting at the bottom of the enclosure. • The reduction in fins volume by half can increase thermal energy storage capacity. [ABSTRACT FROM AUTHOR]

A comprehensive experimental analysis is reported to estimate the heat transfer enhancement in concentric tube type Latent Heat Storage Unit (LHSU) using spiral fins. An angle adjuster is provided in the experimental test facility to facilitate orienting the LHSU at different angles i.e. vertical (θ = 90°), horizontal (θ = 0°) and inclined (θ = 45°). Total 45 temperature probes are installed in the annulus of the concentric tubes for accurate measurement of temperature in radial, axial and angular direction. Provision of fins expedites melting rate, which results in reduction in time required for energy storage. With the installation of the spiral fins, a maximum reduction in the charging time of 51.61% is observed when the test section is aligned in vertical (θ = 90°) orientation. Inclined (θ = 45°) and horizontal (θ = 0°) test section offer 40.97% and 34.1% reduction in the melting time respectively. LHSU integrated with the spiral fins may enable its application to large scale solar thermal applications. [Display omitted] • Heat transfer enhancement in LHSU with spiral fins during charging process. • Comparative assessment with fins for vertical, horizontal and inclined (θ = 45°) orientations. • Maximum reduction in melting time with fins is 51.61% for vertical LHSU. • 40.97% and 34.1% reduction in melting time for inclined and horizontal LHSU. • Vertical LHSU integrated with spiral fins potential for large scale solar thermal storage. [ABSTRACT FROM AUTHOR]

• Numerical investigations to evaluate thermo-hydraulic performance of FTHEs equipped with RWVGs with circular punched holes (1, 2, 4, and 6 holes) are carried out. • Critical comparison is presented between rectangular winglet vortex generator with and without circular punched hole. • RWVG with 6 holes shows up to 45.95% and 57.37% augmentation to Nusselt number for Reynolds number 400 and 2000, respectively with 13.81% reduction in friction factor. • The best performance can be achieved with RWVG with 6 circular punched holes. In fin-and-tube heat exchangers (FTHEs), vortex generation is found as one of the promising emerging passive technique for augmenting the rate of heat transfer on air-side. In the present study, three dimensional numerical study is performed to evaluate thermo-hydraulic performance of FTHEs equipped with rectangular winglet vortex generators (RWVGs) with circular punched holes for Reynolds number varying from 400 to 2000. Various cases of RWVGs without and with circular punched holes (1, 2, 4, and 6 holes) are considered. The pairs of RWVG are placed in common flow down (CFD) orientation behind the circular tubes to improve wake management. The effect of number of punched holes is compared with non-VG baseline case and RWVG without hole for flow structure and thermo-hydraulic performance of FTHE with four inline circular tube arrangement. Comparison is also carried out with thermo-hydraulic performance criterions which include Nusselt number (Nu), Pressure drop (ΔP), friction factor (f), colburn factor (j), London area goodness factor (j/f). Effects of number of punched hole on the performance of RWVGs is also evaluated using dimensionless number (j/j 0)/(f/f 0) as performance evaluation criteria (PEC). It is observed that RWVGs with circular punched holes remarkably improve the thermo-hydraulic performance of FTHE. The punched holes exhibit reduction in the flow resistance for all cases with slight reduction in Nusselt number. RWVG with 6 holes shows better performance as compared to other cases. Nusselt number for RWVG with 6 holes increases about 45.95% and 57.37% at Reynolds number 400 and 2000, respectively. However, friction factor is decreased by about 13.81%. Thus, from the point of view of London area goodness factor, RWVG with 6 holes found better than other considered cases of RWVG. [ABSTRACT FROM AUTHOR]