Horizontal Heat Research Articles

Condensation heat transfer and pressure drop characteristics of Isobutane in horizontal channels with twisted tape inserts

• Using twisted tapes augmented the heat transfer and pressure drops. • The heat transfer rate enhanced by giving rise to vapor quality and mass flux. • The pressure losses increased by giving rise to vapor quality and mass flux. • The performance factor varied between 0.39 to 1.05 using inserts. The enhancement of heat transfer rate in heat exchangers has been considered a major concern. In this research, the impacts of inserting twisted tapes in horizontal two-phase flow heat exchangers are discussed, and different values of vapor qualities (in the range of 0.1 to 0.7) and mass velocities (in the range of 119 to 367 kgm −2 s −1 ) are considered during forced convective condensation of R600a (Isobutane). The test case is a pipe made from copper with an inner diameter of 8.1 mm and a length of 1000 mm. Furthermore, three twisted tape inserts with various twist ratios (defined as the ratio of the twisted tape pitch to the test pipe inner diameter) of 4, 10, and 15 are used. The results illustrated that installing twisted tapes results in the increment of pressure drops and the rate of heat transfer in comparison to the smooth case. Furthermore, the pressure drops and heat transfer rates augment as the refrigerant mass velocity and vapor quality increase. Depending on the inserts type and operating conditions, the performance factor (a criterion to assess the performance modification compared to the primary test case) between 0.39 to 1.05 was obtained. It was also observed that there exists an optimum amount of the refrigerant mass velocity at which the performance factor is higher. Results showed that generally using twisted tapes in heat exchangers is not instrumental unless when the main concern is to improve the heat transfer rate or when the augmented power consumed by pump can be justified.

Numerical investigation of the integration of heat transfer devices into wind towers

The purpose of this study is to incorporate heat transfer devices inside the passive terminal of a wind tower unit, highlighting the potential to achieve minimal restriction in the external air flow stream while ensuring maximum contact time, thus optimising the cooling duty of the device. Computational Fluid Dynamics (CFD) was used to develop a numerical model of a wind tower system and simulate the air flow pattern around and through the device to the test room. Results have indicated that the average internal airflow rate was reduced following the integration of the vertical and horizontal heat transfer device configuration, reductions of 4.11 % and 8.21 % was obtained respectively. Furthermore, the proposed cooling system was capable of reducing the air temperatures by up to 15 K. The technology presented here is subject to IP protection under the QNRF funding guidelines.

Dataset of an in-use tertiary building collected from a detailed 3D mobile monitoring system and building automation system for indoor and outdoor air temperature analysis.

A Mobile Monitoring System (MMS) has been designed taking into account the use of technology with high sensor accuracy and the ability to be installed easily and quickly in different cardinal locations, distribution spaces, volumes and at different heights of a tertiary in-use building located in Leioa (Bilbao). Two types of MMS have been designed with the objective of carrying out two types of analysis; one intended to do a global indoor air temperature uncertainty analysis and the other focused on doing a global outdoor air temperature uncertainty analysis.Eight tripods make up the interior MMS with twenty sensors at different heights, which have been installed in different offices in the building to collect indoor air temperature measurements at different heights and locations. In addition, eight sensors make up the exterior MMS to collect data from outdoor air temperature measurements around the building envelope. Both MMS have been integrated into the existing Building Automation System (BAS) of the tertiary building; some other data collected by the BAS has also been taken into account for the uncertainty analysis of indoor and outdoor air temperature.The interior and exterior MMS datasets have been compiled based on a rigorous data collection process, with the potential to use the data to study the spatial air temperature behavior, taking into account the impact of solar radiation, the heating system and the electrical energy consumption. Furthermore, it enables the global uncertainty of indoor and outdoor air temperature measurements on an in-use building to be estimated and to break it down into the different uncertainty sources, such as the sensor accuracy, vertical and horizontal temperature variability, solar radiation, occupancy and heating system effects. Finally, it enables the optimization of monitoring and control systems for BAS, heating and HVAC systems, as well as any monitoring system implemented in research tests using indoor and/or outdoor temperature measurements as key variables.

МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ ТЕПЛОПЕРЕДАЧИ В ГОРИЗОНТАЛЬНОЙ ТЕПЛООБМЕННОЙ ТРУБЕ

It has been experimentally established that the ideal displacement model adequately describes the heat transfer process in a horizontal heat exchange pipe cooled by atmospheric air

Analogue experiments on morphological transition from colonnade to entablature of columnar joints

We conduct analogue experiments using starch and water mixture to understand the key factors controlling morphological transitions from colonnade to entablature of columnar joints. Columnar joints are formed by volume contraction during cooling. The isotherms are assumed to be perpendicular to the direction of the columns. However, observations of the morphological transition between colonnade and entablature and morphology in the entablature part are complex; it is expected that their formations are caused by a change in the distribution of the isotherms. Analogue experiments using starch and water mixtures have been conducted to reproduce the formation of colonnade (straight columns) but not for curved structures. We conduct experiments to reproduce the curved structures and investigate the process of crack propagation from two non-parallel drying surfaces and the relationship between the water distribution and crack development in the starch and water mixture by observing X-ray computed tomography (CT) images over time. In addition, the numbers of columns and cross-sectional areas are measured to interpret the column nucleation, which causes a decrease in the average column width. Based on analytical and numerical solutions of a simple diffusion equation, we examine the effect of critical temperature for crack initiation on curved structures, with a discussion comparing experimental results. The results and discussions suggest that 1) the curvature in crack development is likely controlled not only by the isotherm but also by the temperature at crack initiation and 2) an instantaneous increase in the cooling rate induces the column nucleation at the crack front. Finally, we propose a scenario of morphological transition from colonnade to entablature at Shakushiiwa, Aso-4 welded tuff, in Japan, which shows a threefold structure (upper colonnade – entablature – lower colonnade) based on our experimental results. We introduce two modes of heat transfers: vertical heat transfer Qd within intact rocks by thermal diffusion toward the upper cooling surface and horizontal heat transfer Qv through the cracks. The transition between the modes induces a drastic change in the shape of the isotherm at the crack front, resulting in the morphological transition from colonnade to entablature.

Reducing energy consumption for electrical gas preheating processes

Gas preheating is a key process to prevent the formation of hydrates in gas stations. In order to ensure safe operation of nearly 900 pressure reduction stations in Poland, it is necessary to provide a significant amount of energy, estimated up to 700 TJ per year. Gas can be preheated by means of gas and electrical technologies, both of which have their advantages and disadvantages. This paper focuses on electrical technologies based on renewable energy sources (RES): air source electric heat pump and ground source heat pump, ground air heat exchangers, horizontal and vertical heat exchangers. The calculation methodology of natural gas parameters for the proposed preheating systems, based on the composition and basic properties of chemical compounds of the fuel, was presented. The analyses were performed for three climate types (cold, average and warm) and for the two assumed modes of operation of pressure reduction station (PRS). The results showed that the electrical preheating solution by RES can save more than half of the primary energy in an environmentally friendly way and reduce the harmful gas emissions. The high coefficient of performance (COP) from 2.1 to 5.7 enables the energy demand to be reduced from 45 kW to 8.1–14.9 kW.

Enhancement of heat transfer performance in pipe flow using graphene-oxide-nanofluid and its application

This paper aims to introduce heat transfer performance of aqueous suspensions in horizontal tube and heat pipe cooling device under constant heat flux condition. Here, pure water and graphene oxide (GO) nanofluid are employed as a working fluid. Consideration is given to the effects of particle concentration on heat transfer enhancement. It is found for pipe flow case that (i) heat transfer enhancement is caused by suspending nanoparticles, (ii) viscosity of GO nanofluid developed here is decreased with an increase in temperature, (iii) but the pressure drop for GO nanofluid, at 293 K, is almost the same as that of pure water, because volume fraction of particles is substantially low. When GO nanofluid is used in a Cu heat pipe cooling device, one observes that (i) thermal performance of heat pipe increases with increasing the concentration of GO nanoparticles in the base fluid, (ii) GO/water nanofluid shows lower thermal resistance compared to pure water, and (iii) heat transfer coefficient of the GO nanofluid in Cu heat pipe significantly increases with an increase in heat flux and GO nanoparticles concentration. This is explained as due to formation of rough inner surface in Cu heat pipe which supports higher heat transfer in GO nanofluid as compared to pure water.

The Building Blocks of Northern Hemisphere Wintertime Stationary Waves

AbstractAn intermediate-complexity moist general circulation model is used to investigate the forcing of stationary waves in the Northern Hemisphere boreal winter by land–sea contrast, horizontal heat fluxes in the ocean, and topography. The additivity of the response to these building blocks is investigated. In the Pacific sector, the stationary wave pattern is not simply the linear additive sum of the response to each forcing. In fact, over the northeast Pacific and western North America, the sum of the responses to each forcing is actually opposite to that when all three are imposed simultaneously due to nonlinear interactions among the forcings. The source of the nonlinearity is diagnosed using the zonally anomalous steady-state thermodynamic balance, and it is shown that the background-state temperature field set up by each forcing dictates the stationary wave response to the other forcings. As all three forcings considered here strongly impact the temperature field and its zonal gradients, the nonlinearity and nonadditivity in our experiments can be explained, but only in a diagnostic sense. This nonadditivity extends up to the stratosphere, and also to surface temperature, where the sum of the responses to each forcing differs from the response if all forcings are included simultaneously. Only over western Eurasia is additivity a reasonable (though not perfect) assumption; in this sector land–sea contrast is most important over Europe, while topography is most important over western Asia. In other regions, where nonadditivity is pronounced, the question of which forcing is most important is ill-posed.

PERFORMANCE ANALYSIS OF COOLING SYSTEM WITH HORIZONTAL TYPE GROUND SOURCE HEAT PUMP FOR DIYARBAKIR CONDITIONS

In this study, the performance of the horizontal type ground source heat pump cooling system in the summer was analyzed for cooling the testing area with a size of 9x8x2.8m in Diyarbakir province with a warm climate. Energy and exergy analysis was applied to the system and system units by examining the results obtained in the summer in the evaluated system. The monthly and seasonal mean values of the data in the summer (01.06.2018 / 30.08.2018 ) were taken for 11 node points determined in the installed system. In the energy analysis performed with the results obtained, it was calculated that the energy loss in the system was 2.499kW and the energy efficiency 76.86%. For the system units, the unit operating with the lowest energy efficiency was determined as the compressor. According to exergy analysis applied to the system, it was calculated that the exergy loss of the system was 2.150 kW and the second law efficiency was 20.70%. The compressor was also determined as the unit with the highest exergy loss in the system. Compressor should be prioritized for improvement studies to be planned according to both energy and exergy analysis results. The COP value of the system was found to be 4.05, and it was determined that the system, the use of which was examined in the summer, could be used for Diyarbakir province.

Impact of Roughness Length on WRF Simulated Land‐Atmosphere Interactions Over a Hyper‐Arid Region

AbstractThe aerodynamic roughness length is a crucial parameter that controls surface variables including the horizontal wind, surface temperature, and heat fluxes. Despite its importance, in the Weather Research and Forecasting (WRF) model, this parameter is typically assigned a predefined value, mostly based on the dominant land‐use type. In this work, the roughness length is first estimated from eddy‐covariance measurements at Al Ain in the United Arab Emirates (UAE), a hyper‐arid region, and then ingested into WRF. The estimated roughness length is in the range 1.3–2.2 mm, one order smaller than the default value used in WRF. In line with previous studies, and from WRF model simulations during the warm and cold seasons, it is concluded that, when the roughness length is decreased by an order of magnitude, the horizontal wind speed increases by up to 1 m s−1, the surface temperature rises by up to 2.5°C, and the sensible heat flux decreases by as much as 10 W m−2. In comparison with in situ station and eddy covariance data, and when forced with the updated roughness length, WRF gives more accurate 2‐m air temperature and sensible heat flux predictions. For prevailing wind speeds >6 m s−1, the model underestimates the strength of the near‐surface wind, a tendency that can be partially corrected, typically by 1–3 m s−1, when the updated roughness length is considered. For low wind speeds (<4 m s−1), however, WRF generally overestimates the strength of the wind.

Heat Transfer Enhancement of Horizontal Oscillating Heat Pipes With Micro-/Nanostructured Surface

Abstract For oscillating heat pipes (OHPs) with low turn number (<9) positioned in the horizontal direction, the working fluid could not easily flow back to the evaporator due to the absence of gravity. Based on this, copper OHP with superhydrophilic micro-/nanostructured surface was investigated to enhance the heat transfer performance by introducing additional capillary force. OHPs with six turns were fabricated with bare copper and micro-/nanostructured inner surfaces for comparison. Pure water was used as the working fluid. Contact angles of water on the copper and superhydrophilic surfaces were 36.7 and 0 deg, respectively. The filling ratios of water were 50%, 65%, and 80%, respectively. Thermal resistance and liquid slug oscillations of OHPs were investigated at the heat input ranging from 100 to 380 W. Experimental results showed that OHPs with the superhydrophilic micro-/nanostructured surface showed an enhanced heat transfer performance due to the micro-/nanostructure-induced capillary flow in the horizontal direction. The optimum filling ratio was 65% in this work. The superhydrophilic micro-/nanostructured surface could significantly facilitate the backflow of the working fluid to the evaporator section and accelerate oscillating motions of liquid slugs. With the increasing of 0–70% in slug oscillating amplitude and 0–100% in slug oscillating velocity, micro-/nanostructured OHPs improved the heat transfer performance by up to 10% compared with the copper OHPs due to the wicking effect.

What did determine the warming trend in the Indonesian sea?

The Indonesian sea is the only low-latitude pathway connecting two tropical oceans, which plays an important role in the coupled ocean-atmosphere mode in the Indo-Pacific sector. A small change in the sea surface temperature (SST) in the Indonesian sea has a significant influence on the precipitation and air-sea heat flux. During the past 33 years, the SST in the Indonesian sea has indicated a warming trend on the average of 0.19 ± 0.04 decade−1, which is larger than global SST warming trend. Moreover, the warming trend indicates seasonal variations, in which maximum trend occurred during boreal summer season. Investigation on the potential driver for this warming trend, namely, the net surface heat flux, resulted in an opposite trend (cooling trend), while the Ekman pumping and the wind mixing only play a minor role on the SST warming. Here, we proposed the upper layer process associated with an increasing trend in precipitation and decreasing trend in mixed layer depth (MLD) for the SST warming within the Indonesian seas. Shoaling of MLD gives a favorable condition for the surface heat flux to warm the surface ocean. However, shoaling of MLD could not solely explain the total SST warming within the Indonesian seas. The seasonal dependence in the warming trend, highest during boreal summer, was significantly related to the Indo-Pacific climate modes, namely the negative Indian Ocean Dipole (IOD) and La Niña events. Higher warming trend observed in the south of Makassar Strait and in the eastern Indonesian seas, in the vicinity of the Maluku Sea and the northeastern part of the Banda Sea, was significantly associated with the La Niña event. Meanwhile, strong warming trend observed in the Karimata Strait and Java Sea, and in the Flores Sea south of Sulawesi Island seems to be enhanced by the negative IOD event. Our rough quantitative estimate of the possible mechanism leading to the SST warming suggests that other mechanism might be at work in warming the SST within the Indonesian seas. Horizontal heat advection associated with an increasing trend of the heat transport from the Pacific into the Indian Ocean by the Indonesian Throughflow (ITF) might play a role in causing the warming trend within the Indonesian seas. However, to what extend this heat advection could modulate the SST warming is still unresolved in the present study. Further study based on realistic model output as well as long-term observational records is necessary to describe the dynamics underlying the warming trend within the Indonesian seas.

System efficiency of pvt collector-driven heat pumps

Abstract The use of standard heat pump (HP) systems offers an efficient option to replace conventional heating systems (e.g. oil and gas boilers) for space heating and domestic hot water. Due to the higher noise emissions and the lower overall energy efficiency of air-to-water heat pumps, the use of ground-coupled heat pump systems is increasingly in demand. The cost-efficient dimensioning of horizontal ground heat exchanger (HGHE) systems, considering possible solar waste heat potentials to improve regeneration behaviour, is particularly challenging. The reason for this is the complex system and control engineering optimisation possibilities resulting from the dynamic heat transport behaviour of the horizontal ground heat exchanger. Essential influencing variables such as the water content of the soil due to the groundwater level, rainwater infiltration and surface evaporation can only be described with massive effort using the model equations of the unsaturated zones. However, these variables are necessary to obtain a better fundamental understanding of the usable storage potential of solar-coupled systems and to be able to derive targeted optimisations at the system level. Therefore, the waste heat utilisation potential of PVT collectors for the regeneration of heat pump coupled horizontal ground heat exchanger systems are analysed employing simulations. For this purpose, a PVT-collector model and a HGHE model based on a single-family were developed and validated by experimental investigations. Based on this, a system simulation model consisting of the components PVT-collector, heat pump, heat delivery system, HGHE and the corresponding control units were built using TRNSYS. With the help of the simulation model, parameter studies were carried out, and the main factors influencing the overall energy efficiency (COP) of the system and the seasonal performance factors (SPF) were identified. Furthermore, the solar waste heat utilisation potential of the PVT collectors was analysed to increase the efficiency of the heat pump system.

Heat and mass transfer modeling of R-245fa and R1233zd(E) with concurrent boiling and convective evaporation in falling film applications

Abstract Design of some thermal industrial equipment like Heating Ventilation and Air Conditioning falling film evaporators and desalination units requires knowing discrete portion of convective evaporation and boiling. While most models are based on sole dominant evaporation, one small variation in design parameters can increase boiling part and threaten the model. Heat transfer simulation of such equipment is dependent on mass transfer modeling. Therefore, this study uses different mass transfer models and numerically investigates two laminar falling film flows around a horizontal tube heating insomuch that leads to sole evaporation and evaporation with boiling. The multi-phase volume of fluid model is used and the performance of mass transfer models is investigated for heat transfer coefficient, film thickness, bubble generation and liquid superheating. Results show that for 240 mL*min−1 of R-245fa at saturation pressure of 123.8 kPa at wall and saturation temperature difference of below 7 K, main contribution of heat transfer is due to evaporation which is accurately modeled by Tanasawa and Lee phase change models. With increasing wall heat flux, boiling portion signifies. Accordingly, Tanasawa model is not able to simulate boiling part but Lee model predicts total heat transfer coefficient with 7% error. After validating the numerical model, the model has been used for R1233zd(E) as a low Global Warming Potential refrigerant and transition to boiling presence of the falling flow is investigated. Comparison of the results represents governing evaporation up to 7 K of wall and saturation temperature difference of R1233zd(E) at similar saturation temperature of R-245fa.

The Interannual Cycle Features of the Tropical Pacific-Indian Ocean Associated Mode and Its Mechanisms

Li, X.; Xia, F.; Chen, X.; Shu, X.; Yang, M.; Li, L., and Wang, D., 2020. The interannual cycle features of the tropical Pacific-Indian Ocean associated mode and its mechanisms. In: Zheng, C.W.; Wang, Q.; Zhan, C., and Yang, S.B. (eds.), Air-Sea Interaction and Coastal Environments of the Maritime and Polar Silk Roads. Journal of Coastal Research, Special Issue No. 99, pp. 364–372. Coconut Creek (Florida), ISSN 0749-0208.Based on the SODA ocean analysis data, the interannual cycle features of the tropical Pacific-Indian Ocean associated mode (PIOAM) are studied by means of wavelet analysis and synthetic analysis. It is pointed out that PIOAM has a quasi-biennial cycle and a 3-4-year cycle. Furthermore, the dynamic and thermal mechanisms of the PIOAM interannual cycle are analyzed. The results show that the anomaly of Walker circulation over the two oceans is the key factor which forms the PIOAM. The propagation and reflection of ocean waves and the horizontal and vertical heat transfer of ocean circulation also play an important role in the cycle of PIOAM.

Reflective insulation assemblies for above-ceiling applications

Previously published hot-box data have been used to construct equations for the thermal resistance of enclosed reflective air spaces (reflective insulation assemblies) for a wide range of temperatures, air gap dimensions, thermal emittances, and heat flow directions. The thermal resistances or R-values (RSI) calculated with the equations compare favorably with previously published thermal resistances. Significant differences from RSI values (m2 K/W) calculated using ISO 6946 were observed. Equations for calculating heat transfer coefficients for conduction–convection with constants for the heat flow directions up, 45° up, horizontal, 45° down, and down are contained in this article. The conduction–convection coefficient for planar air spaces oriented at any angle and heated above can be obtained by interpolation between heat flow down and heat flow at a downward angle of 45° or heat flow down at an angle of 45° and horizontal heat flow. The overall heat transfer coefficient is obtained by adding the thermal radiation contribution to the conduction–convection contribution. The RSI of enclosed reflective air spaces is the reciprocal of the overall heat transfer coefficient for the air space. This air space RSI is especially useful as input for the calculation of U-values for ceiling–roof assemblies located in hot climates.

Film boiling heat transfer prediction of liquid nitrogen from different geometry heaters

In the present paper, available experimental data and predictive correlations on cryogenic film boiling heat transfer are summarized and analyzed. A unified correlation formation, which could standardize the most of the existing heat transfer correlations, is used to perform comparison studies, and a series of validated correlations focusing on predicting cryogenic boiling events are reached. It demonstrates that Merte & Clark correlation and Bromley correlation are recommended to predict cryogenic film boiling heat flux at spherical and horizontal tube heaters respectively, and the deviations are within ±15% and ±8%. A preliminary data analysis indicates that Laplace reference length could be regarded as a critical diameter to distinguish tube and wire conditions. Moreover, a unified correlation without considering surface orientation effect is proposed to account for the plate heater boiling issue in the view of engineering application, and the deviations are within ±40%. Generally, the present study could provide researchers with reliable research tools to conduct cryogenic heat transfer analysis.

Evaluation and optimization of melting performance of latent thermal s

In the present work, the phase change materials (PCMs) melting characteristics with partial metal foam filled in horizontal concentric tube heat accumulator are numerically investigated. The thermal response of PCMs is improved by using porous media. By comparing the properties of different porous configurations, the position of porous inserts is optimized. According to the thermal reservoir rate density, the optimal arrangement of porous embeds is determined. The results show that this method can effectively investigate the melting performance of materials, such as complete melting time, thermal storage capacity and total materials mass. The results indicate that the best melting performance of PCMs structure is 18 radial porous fins and the optimal length of radial porous fins is the ring width. Comparing with the no porous media case, the thermal storage rate density has increased over 2.6 times obviously. It's worth noting that compared with the full porous media case, the comprehensive performance is reduced by 46.7%, while the porous material is reduced by 80%. The optimized scheme has better heat storage performance and lower cost.

How far poleward can the seasonal precipitation maxima over land extend under high obliquity?

The seasonal response of the poleward extent of continental precipitation maxima to high obliquity and its controlling mechanisms are examined using the NCAR-CESM and Budyko-Sellers energy balance model. In CESM, the latitude of the poleward-most continental precipitation maximum (denoted as $${\phi }_{mp})$$ migrates poleward with increased obliquity, but is limited to equatorward of the latitude of maximum daily insolation. Some insight is gained on the controlling mechanism of the migration of $${\phi }_{mp}$$ in the Budyko–Sellers model, assuming $${\phi }_{mp}$$ coinciding with the position of maximum surface moist static energy (denoted as $${\Theta }_{mp}$$) as in the present-day observation and CESM pre-industrial simulation. Heat capacity exerts a primary control on $${\phi }_{mp}$$ such that $${\phi }_{mp}$$ is determined by the position of maxima of accumulated insolation over the radiative relaxation time and therefore lies equatorward of the maximum daily insolation. Variations of surface albedo and horizontal heat transport, as secondary effects, further shift the $${\phi }_{mp}$$. This understanding from the Budyko-Sellers model, however, fails in CESM in the case of high obliquity of 40°, with $${\phi }_{mp}$$ now lying equatorward of $${\Theta }_{mp}$$. This separation between $${\phi }_{mp}$$ and $${\Theta }_{mp}$$ is explained by the constraint of rotation on the latitudinal range of weak temperature gradients, which is the prerequisite for the prediction of $${\phi }_{mp}$$ from $${\Theta }_{mp}$$. When the rotation rate is reduced, the latitudinal range of weak temperature gradients expands poleward roughly following the change of the equatorial Rossby radius, allowing $${\phi }_{mp}$$ moving close to $${\Theta }_{mp}$$.

Enrichment of heat transfer in a latent heat storage unit using longitudinal fins

AbstractThe 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.