Heat Sink System Research Articles

Enhancing Long-Term Viability of Energy Pile with Heat Sink Systems in Tropical Monsoon Climates: Implementation Strategies and Performance Analysis

Energy piles, a form of ground-source heat pump system integrated into building foundations, show great potential for reducing building energy consumption associated with fossil fuels. While it excels in climates where cooling demand matches heating, its effectiveness faces challenges in tropical monsoon regions characterized by hot summers and cool winters. In such climates, cooling demand dominates, leading to significant thermal accumulation over time, which diminishes the long-term viability of energy pile systems. This study focuses on the long-term thermal behavior analysis of an energy pile system installed in a representative office building. Our approach begins with an examination of short-term behavior, followed by the creation of a simplified model. Using this model, we analyze the long-term behavior of different systems, including the standard energy pile and combinations with various solutions: natural groundwater flow and synthetic heat sink systems. Key outcomes are evaluated based on entering water temperature (EWT), soil temperature, and energy efficiency ratio (EER), while also comparing energy savings with conventional air conditioning systems. Major findings include: (1) Standard energy pile systems without any mitigation measures achieve only a 15.3% energy savings initially and may cease functioning after approximately 10 years, (2) Energy pile systems using specific solutions can achieve a maximum saving ratio of 50%, typically ranging from 30% to 45%, while maintaining stability over the designated lifespan, (3) Higher EER and saving ratios correlate with increased groundwater flow and larger heat sink systems, however, the relationship is nonlinear, emphasizing the need for tailored design under varying geology and climate conditions. This study provides essential insights into energy pile systems design and practical guidance, along with expected energy savings in tropical monsoon climates for future application.

Design of a thermoelectric cooler to control the temperature of telecom outdoor cabinet

This paper discusses the design of a thermoelectric cooler (TEC) system for controlling the temperature of telecom outdoor cabins. Traditional cooling methods, such as refrigerants, have potential negative impacts on the environment, making thermoelectric cooling systems a promising alternative due to their efficiency, environmental friendliness, and versatility. The paper reviews the current state of the art in designing thermoelectric cooler systems for absorbing heat generated from telecom electronic devices. The literature review highlights studies that have evaluated the cooling performance, energy efficiency, and cost-effectiveness of thermoelectric cooling systems for telecom electronic devices. The objective of this project is to design a TEC system that can absorb the heat generated from telecommunication cabinets. The design is generated analytically using the TE ideal equation with a heat sink or heat exchanger system. The design aims to investigate the optimum current and geometric ratio that can improve the cooling capacity of the TEC system. The paper also presents a modeling approach for thermoelectric coolers with two heat sinks. The study concludes that thermoelectric cooling systems have the potential to provide efficient and environmentally friendly cooling solutions for telecom electronic devices, and future studies should continue to investigate and optimize the design of thermoelectric cooling systems for various types of telecom electronic devices.

Ab-initio insights into the mechanical, phonon, bonding, electronic, optical and thermal properties of hexagonal W2N3 for prospective applications

We thoroughly investigated the structural, mechanical, electronic, vibrational, optical, thermodynamic, and a number of thermophysical properties of W2N3 compound through first-principles calculations using the DFT based formalism. The calculated structural parameters show very good agreement with the available theoretical and experimental results. The mechanical and dynamical stabilities of this compound have been investigated theoretically from the elastic constants and phonon dispersion curves. The Pugh's and Poisson's ratios of W2N3 are located quite close to the brittle/ductile borderline. W2N3 is elastically anisotropic. The calculated electronic band structure and density of states reveal that W2N3 is conducting in nature. The Fermi surface topology has also been explored. The analysis of charge density distribution map shows that W atoms have comparatively high electron density around compared to the N atoms. Presence of covalent bondings between W–N, W–W, and N–N atoms are anticipated. High melting temperature and high phonon thermal conductivity of W2N3 imply that the compound has potential to be used as a heat sink system. The optical characteristics show anisotropy. The compound can be used in optoelectronic devices due to its high absorption coefficient and low reflectivity in the visible to ultraviolet spectrum. Furthermore, the quasi-harmonic Debye model is used to examine temperature and pressure dependent thermal characteristics of W2N3 for the first time.

Progress in Fast Modular Reactor Conceptual Design

The Fast Modular Reactor (FMR) is a 100-MW(thermal) gas-cooled fast reactor being developed by General Atomics Electromagnetic System with the goal of developing a FMR for flexible and dispatchable power to the U.S. electricity market in the mid-2030s. The conceptual design aims to develop and verify simplified design features. These include an inert helium gas coolant, pellet-loaded fuel rods, installations with air cooling as ultimate heat sink, and small and passive heat removal systems. The goal is to ensure the development of a safe, maintainable, cost-effective, and distributed nuclear energy-generating station. The baseline technologies selected to achieve this goal are a helium coolant that is an inert gas with no chemical reaction with structural components, not activated, single phase, enabling high-temperature operation and a high thermal efficiency Brayton cycle; conventional uranium dioxide (UO2) fuel, which is the most widely used and well-known fuel material, capable of high burnup (100 MWd/kg) and a long fuel life; and silicon carbide composite (SiGA®) cladding and internal structures that are chemically inert in the helium environment, exceptionally radiation tolerant, and being derisked by accident tolerant fuel technology development. The reactor was specifically designed with passive safety features, including high-temperature in-core materials and a reactor vessel cooling system consisting of cooling panels of naturally circulating water. The passive safety of the core was confirmed for the depressurized loss-of–forced cooling accident, which showed the peak cladding temperature at ~1600°C during the transient, which is below the current design limit of 1800°C. The conceptual design of the FMR has been conducted for the reactor system, vessel system, generator and turbomachine, instrumentation and control, residual heat removal system, plant service system, and containment, as well as pre-application licensing documents.

Experimental study on the bionic microchannel heat sink integrated with a piezoelectric pump

The increased integration of electronic chips and the miniaturization of electronic products significantly raise the heat generated by electronic devices. To meet the cooling requirements of highly integrated electronic devices and enhance the cooling performance of the piezo-driven cooling system, a piezo-driven microchannel liquid-cooling system for CPU chip cooling was developed. The system integrated a bionic microchannel heat sink and a piezoelectric pump with umbrella valves (PP-UV). The piezoelectric pump was used as the driving source to propel the coolant flow, and the output of the piezoelectric pump pulsated, contributing to the convective heat transfer of the fluid in the microchannel. The spider web microchannel heat sink (SWM-HS) was designed and compared with the tandem Y-shaped microchannel heat sink (T-YMHS). The performance of the piezo-driven microchannel heat sink system with different structured microchannel heat sinks was studied by combining experimentation and simulation. The results indicated that the SWM-HS cooling system exhibited better fluid transmission and cooling characteristics, along with lower input power (3.32 mW). When the drive voltage was 100 V, the output flow of the SWM-HS cooling system was 56.4 mL/min. With a thermal power consumption of 30 W, the CPU temperature remained stable at approximately 55 °C, while the total thermal resistance measured 0.183 °C/W. In comparison with T-YMHS, the internal pressure drop of the SWM-HS decreased by 20.7 %, the Nusselt number increased by 13.7 %, and it achieved a cooling efficiency of 64.48 %. The experimental results aligned well with the simulation results. This work contributes to advancing the application of piezoelectric devices in electronic cooling and enhancing the cooling efficiency of miniature cooling systems.

HEAT TRANSFER ANALYSIS OF A COMBINED PIEZOELECTRIC FAN–TRANSLATIONAL AGITATOR COOLING SYSTEM

This paper investigates the heat transfer characteristics of a channel system consisting of a finned heat sink and two piezoelectric devices, the piezoelectric fan (PF) and the piezoelectric translational agitator (PTA), both experimentally and computationally. In the proposed system, the mean flow is generated by a cantilevered PF, and the flow between the fins is agitated using a PTA. A single-channel system consisting of a PTA, the PF, and two fins is analyzed numerically using ANSYS Fluent software after validating numerical predictions against experimental measurements. The effect of design variables such as frequency ratio, phase difference, PF's tip distance from PTA, and squeezing fraction is explored. A PTA increases the heat transfer from the heated surfaces without incrementally aiding in the mass-flow rate. Velocity and temperature fields are plotted to understand the physics of the system for one complete cycle of a PTA blade. The concept of total Reynolds number that incorporates the effect of both axial and transverse fluid flow is used in this study. The Nusselt number increases with an increment in the total Reynolds number. It is noted that the integration of the PF and the PTA with the finned heat sink system has enhanced the heat transfer coefficient by 76.88% compared to the system with PTA and by 30.92% as compared to the system with the PF only.

Investigation on the thermal control and performance of PCM–porous media-integrated heat sink systems: Deep neural network modelling employing experimental correlations

Phase change material (PCM)-based heat sinks can offer reliable and effective thermal management (TM) solutions for increasingly sophisticated applications. A critical aspect of such heat sinks is determining how long it takes them to reach a set-point temperature. However, no generalised method exists in the literature that can predict and interpret the thermal performance of a wide range of PCM–porous media-integrated heat sinks. In this regard, this study examines the heat transfer characteristics of PCM-based heat sinks integrated with various metallic foams through experimental and deep learning (DL) techniques. The experiments are performed for transient TM analysis of various PCM-based heat sinks. Diverse variables, including foam porosity (0.95–0.97), PCM fraction (0.6–0.8), heat flux (0.8–2.4 kW/m2), foam materials (Fe–Ni alloy, Ni and copper) and PCM type (RT-35HC, RT-44HC, RT-54HC and paraffin wax), are investigated in this study. The experimental data are fed to the optimal DL model using the Bayesian surrogate model-tuned hyperparameters. Utilising a correlation analysis, as exemplified by the heat map and correlation plot, in conjunction with explainable artificial intelligence, it has been deduced that the thermal performance of the heat sink is principally influenced by factors such as PCM type, PCM fraction, foam material, foam porosity, and heat flux. Comparing the model's predicted data with the empirical findings, a good agreement was observed. Specifically, the mean absolute error (MAE) for the anticipated temperature and gradient registered at 0.0438 and 0.0054, whilst the mean square error (MSE) manifested values of 0.0579 and 0.0087, respectively. The proposed model can accurately assess the heat sink's thermal performance (correlation coefficient, R2 = 0.99) for various PCM types, fractions, foam materials, applied heat flux and foam porosity.

Multi-objective inverse design of finned heat sink system with physics-informed neural networks

This study proposes a new inverse design method that utilizes a physics-informed neural network (PINN) to parameterize the geometric and operating inputs, enabling the identification of optimal heat sink designs by starting with the desired objectives and working backward. A specialized hybrid PINN is designed to accurately approximate the governing equations of the conjugate heat transfer processes. On this basis, a surrogate model derived from the hybrid PINN is constructed and integrated with multi-objective optimization and decision-making algorithms. The results of an example finned heat sink system are presented, showcasing the accelerated search for Pareto-optimal designs. The proposed method nearly halved the search time to approximately 113.9 h in comparison with the traditional methods. Moreover, three representative scenarios—high-performance design, equilibrium design, and low-cost design —were compared to visualize the real-time changes in the multiphysics field, facilitating improved physical inspection and understanding of the optimal designs.

Autonomous Thermosiphon System of Passive Residual Heat Removal from the Primary Circuit of the Reactor Plant: Features of Operation, Characteristics and Basic Advantages

An autonomous system of passive removal of residual heat (PRRHS) of a reactor installation with VVER designed to ensure the safety of nuclear power plants in an accident with complete long-term blackout is considered. The system provides for the removal of heat directly from the first circuit of the reactor plant (PRRHS R). In order to increase the reliability and safety of the emergency heat sink, heat exchange equipment based on closed-type evaporation and condensation devices – two-phase thermosyphons – has been used in the system. The main feature of such heat exchangers is that their thermosiphon assemblies structurally separate the primary circuit and the auxiliary circuit of the PRRHS, which is removed outside the reactor compartment, and provide safe and efficient heat removal, reduce the risk of radioactive contamination spreading beyond safety barriers. Such autonomous passive systems will provide effective heat removal directly from the primary circuit by changing the chain of successive heat transfer sites from nuclear fuel to the final absorber and excluding from it such elements, as for example steam generators, the condition and operability of which in the emergency process of heat removal have a major impact on the safety of the reactor core. The article presents a diagram of an autonomous heat sink system; also, a description of its operation is given. The main characteristics of the course of the emergency process of removal of residual heat by the autonomous thermosiphon PRRHS R obtained by computational modeling have been considered. The advantages of an autonomous thermosiphon passive system in comparison with a passive heat removal system of a reactor installation with VVER through the second circuit are analyzed. The obtained results are proposed to solve the problems of diversification of passive safety systems of evolutionary reactor plants of nuclear power plants with VVER type reactors.

Assembly Device for Supermodules of Silicon Tracking System of the BM@N Experiment

The silicon tracking system of the BM@N experiment consists of four stations based on double-sided microstrip silicon sensors. The sensors make it possible to obtain a spatial resolution for tracks of secondary charged particles up to 17 μm. Two ASIC boards, the input channels of which are connected to the strips with ultralight (0.23% X0) aluminum flex cables, are used to readout and process signals from both sides of the sensor. Such an assembly is called a module. Silicon sensors are mounted on lightweight carbon-fiber support trusses in a way that the dead zones at the edges are overlapped due to the tiled layout. The frontend electronics are housed in metal containers with a heat sink system located at the rare ends of the carbon-fiber support truss. A set of modules attached to the carbon-fiber support truss with two containers with readout electronics at the ends is called a supermodule. The accuracy of the sensor positioning in the station plane plays a crucial role in limiting the degrees of freedom of the parameters determined by the software during the final alignment of the tracking system elements. A special device that allows mounting sensors on a carbon fiber truss with an accuracy of up to 15 µm on a 1200 mm base is developed to assemble supermodules. The results of testing the device are given.

Novel design of thermo-electric air conditioning system integrated with PV panel for electric vehicles: Performance evaluation

Traditional air conditioning may be inappropriate for electric vehicles due to its moving parts noise besides using chlorofluorocarbons that harm the environment. In addition, it consumes a significant portion of the stored energy in batteries, reducing the vehicle's driving range. So, in this paper, a novel design of thermo-electric cooling (TEC) system coupled with a photovoltaic (PV) panel replacing the vehicle roof is studied. This system consists of a sandwich of PV panel outside the vehicle and TEC inside with a heat sink system integrated between them. The air temperature variation in the cabin during the daytime is predicted by solving a complete mathematical transient thermal model of the whole system before and after mounting the cooling system. The air streams through the vehicle moving are exploited to improve the TEC and PV system performance. The system performance is investigated for different cases during the day with and without including the PV output power and for the vehicle parks inside or outside. The results indicate that, for each scenario, the number of used TEC modules influences the system performance where the best number varies between 128 and 98. Coupling the PV panel with the TEC system reduces the daily required energy from batteries by about 19%. Running the TEC system during parking from 8 to 10 am decreases the cabin air temperature from 47.5 to 34°C while the input power declines by about 45%, which reduces the interior temperature to 25°C in 10 min (transition time). The contribution of the PV panel based on the studied conditions can increase the range of the vehicle by 10.4 km/day and about 160kWh/year energy saving. The reduction in the input power during transition time reaches 27.8% when the vehicle speed increases from 30 to 60 km/h, while this ratio declines to 10.8% as the vehicle speed rises from 60 to 90 km/h. During vehicle moving, powering the TEC system by the PV panel only can prevent the cabin temperature from rising over 40°C, whereas during parking, there is an optimum fan air velocity that gives the maximum reduction of the cabin temperature.

Thermal and hydrodynamic management of a finned-microchannel heat sink applying artificial neural network

Thermal management of microelectronic circuits will be one of the most difficult challenges facing engineering processes in the near future. High operating temperatures in these devices can degrade the reliability of the components and reduce their life. Therefore, effective cooling technologies that can disperse the significant heat load from the surface of microelectronic equipment are required. An appropriate microchannel heat sink (MCHS) system with optimized geometry can be one of the reliable choices. In the current work, an artificial neural network (ANN) is exerted to optimize the geometry of a finned-MCHS. The distance of fins from the inlet in the second row (l), the distance of fins from the side walls in the first and third rows (t), and the angle of hexagons (θ) are the input parameters. According to the obtained results, the ANN model with a coefficient of determination of 0.999 performed well in predicting the Nusselt number (Nu) and pressure drop (ΔP). Among the investigated input parameters, the variations of the parameter of t affected the thermal and hydrodynamic properties of the device noticeably. Besides, the ANN model suggested that when the optimum values of input parameters (i.e., l = 7.636 mm, t = 4 mm, and θ = 140) are used for the hexagonal fins inside a microchannel, the maximum relative efficiency index of 1.491 can be acquired.

PV-TEG output: Comparison with heat sink and graphite sheet as heat dissipators

This paper finds that PV-TEG systems are well-researched. Different techniques are applied to regulate the heat (or dissipate the heat) in these systems. However, the research shows insufficient data regarding TEG as a heat-utilizing and heat-to-electrical energy-converting agent. So, this paper shows the usage of graphite sheets and heat sinks with PV-TEG systems and their comparison. The investigation demonstrates that at 823 W/m2 of solar irradiation, PV-TEG without heat dissipators transforms PV backside heat into TEG DC voltage of 0.727 V; PV-TEG with graphite sheet TEG voltage is 0.889 V; and PV-TEG with heat sink TEG voltage is 1.476 V. The PV-TEG with graphite sheet system improves TEG voltage up to 0.241 V and DC voltage gain up to 0.75 times for TEG alone. In addition, the temperature difference between the hot side and cold side is up to 3.92 C. PV-TEG with a heat sink system improves TEG voltage up to 0.749 V, provides a DC voltage gain of up to 1.78 times for TEG alone, and increases the temperature difference between the hot side and the cold side up to 5.96 °C.

Hybrid [formula omitted]-[formula omitted] nanoparticles-based eutectic phase change materials for enhancement of thermal efficiency of pin-fin heat sink arrangement

This work reports the synthesis and characterization of hybrid nanoparticles-based phase change material (HNbPCM) along with a practical approach in the pin-fin heat sink system. In particular, the hybrids of Nickel cobaltite (NiCO4O4) - Nickel ferrite (NiFe2O4) nanoparticles (NiCo−NiFe) were synthesized by traditional sol–gel method. The (HNbPCM) composites were then prepared by suspending the nanoparticles in paraffin wax (PW) and polyethylene glycol-6000 (PEG−6000) eutectic organic PCMs with various weight fractions (ϕ=1%–5%). The surface texture, physical and chemical interaction of hybrid nanoparticles and its dispersion in the HNbPCM composites were comprehensively analyzed. The cyclic thermal stability, thermal conductivity, and charging and discharging of characteristics of the developed nano-composites were also confirmed by transient hot-wire apparatus, thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC). A nanoparticles concentration of 3wt% in the HNbPCM shows a promising enhancement in the thermophysical properties. The thermal conductivity of HNbPCM was improved by 304.4% by adding hybrid NiCo-NiFe nanoparticles with ϕ=5%. In addition to thermal conductivity augmentation, nanoparticles enriched HNbPCM altered the phase transition process and eliminated super-cooling by maintaining the high latent heat capacity of 188.95J/g in the melting phase and 189.70J/g in crystallization phase. A systematic experimental framework of thermal performance characteristics for HNbPCM composite in rectangular pin-fin heat sink subjected to steady state heat transfer for effective and reliable cooling was also studied. The cooling of heat sinks was under testimony at different power inputs, volume fractions and modes of heat transfer in two distinct case studies with and without PCM. A volume fraction of 3wt% shown the best thermal performance with a heat transfer enhancement up to 3.2kW/m2 with 18°C temperature reduction in operational time, specific heat capacity, and thermal conducting ability. An improved thermal performance shows considerable thermal and chemical stability, which can expedite the transition process and makes it a desirable prospect for superior thermal energy storage (TES) applications.

Effect of fluid distribution on the cooling performance of hybrid microchannel and slot-jet impingement system

Hybrid microchannel heat sink and slot-jet impingement system (MCSJ) is favored by researchers for its advantages in the cooling of high-heat-flux electronic device. In this study, the effect of fluid distribution on the hydraulic and thermal performance of MCSJ is numerically investigated with a realizable k-ε turbulence model. Firstly, the influence of the cooling water entrance position on the turbulent flow and heat transfer characteristics of MCSJ was studied. It is found that the MCSJ-2 exhibits the best cooling performance. Compared with the conventional design (MCSJ-5), when the inlet water velocity was set as v = 6 m/s, 8 m/s, and 12 m/s respectively, the total thermal resistance of MCSJ-2 decreased by 2.43 %, 2.07 % and 0.71 %, correspondingly; and the temperature difference of the bottom surface in MCSJ-2 decreased by 11.08 % (v = 6 m/s), 6.86 % (v = 8 m/s), and 4.99 % (v = 12 m/s), respectively. Measures to improve the uniformity of fluid distribution among the microchannels in MCSJ-2 were then analyzed. The results show that inserting fin-ribs in the distribution chamber of MCSJ-2 can effectively decrease the pressure drop and improve the thermal uniformity performance of the hybrid system. The fin-ribs’ height and length have different effects on the hydraulic and thermal performance of MCSJ-2.

The role of clinical engineers in the coronavirus disease 2019 pandemic.

The duties of a clinical engineer (CE) during the coronavirus infection 2019 (COVID-19) pandemic were diverse. The original duties of a CE included operation and maintenance of life support equipment used for respiratory therapy, hemodialysis, and extracorporeal membrane oxygenation. The management of life support equipment is critical. The PB-840 ventilator is equipped with a heat sink system that dissipates internal heat through thermal conduction. Therefore, internal contamination is less likely to occur. The exhalation filter used in the PB- 840 can be used for up to 15 days. It can be used for long periods of time without maintenance, reducing the risk of infection. The PB-840 is a suitable device for patients with COVID-19. Its use in critically ill patients was determined to be a priority. Thus, use of an appropriate device for infection control requires a proper understanding of and familiarity with the device in question.

Thermal Performance of the Thin Heat Pipe for Cooling of Solid-State Drives

With the rapid development of information science and technology, the demand for computer data processing is increasing, resulting in the rapid growth of the demand for high-power and high-performance solid-state drives (SSDs). The stable operation of SSDs plays an important role in ensuring the reliable working conditions and appropriate temperature of information technology equipment, rack servers, and related facilities. However, SSDs usually have significant heat emissions, putting forward higher requirements for temperature and humidity control, and consequently the heat sink system for cooling is essential to maintain the proper working state of SSDs. In this paper, a new type of thin heat pipe (THP) heat sink is proposed, and the heat transfer performance and cooling effect are experimentally and numerically studied. The numerical results are compared with experimental results, which showed an error within 5%. Single and double heat pipes were investigated under different input powers (from 5 W to 50 W) and different placement angles between 0° and 90°. The heat transfer performance of the new heat sink is analyzed by the startup performance, the evaporator temperature, and the total thermal resistance. The results show that the new double THPs with a 90° angle have a great advantage in the heat transfer performance of SSDs. The research is of great significance for the design and optimization of the SSDs’ cooling system in practical applications.

Interplay of wettability and confinement enhancing the performance of heat sinks

• Tapered Double layer heat sink performance is enhanced by modifying surfaces (slip). • Value of slip length has been obtained using Molecular Dynamics simulation. • Analysis has been done based on both the first law and the second law of thermodynamics. • Entropy generation rate due to changes in kinetic energy has been introduced. • The optimal design of a double-layer microchannel heat sink has been obtained. Engineering microchannel heat sinks can help to develop compact and highly efficient cooling systems for electronic devices. In the present study, we demonstrate the coupled effect of surface modification and confinement on the performance of Double Layered Microchannel Heat Sink (DL-MCHS). The effect of wettability is incorporated using interfacial slip obtained from Molecular Dynamics (MD) simulations performed for various wettabilities, and the effect of confinement, through varying tapering degrees, is directly embodied in the geometry. The coupled transport equations are solved using the Finite Element Method (FEM) to depict the thermo-hydraulic characteristics of DL-MCHS. We quantified the enhancement in hydraulic performance and thermal performance of DL-MCHS with varying degrees of surface modification and varying tapering. For the first time, we demonstrate a regime where thermal and hydraulic performances can be enhanced simultaneously in tapered DL-MCHS thereby, making the configuration a viable heat sink system. Also, for the first time, we perform an entropy generation rate analysis in tapered DL-MCHS and demonstrated ways to reduce irreversibility making it a thermodynamically advantageous system, and following that perform an all parameter optimization study. We show that by tuning the tapering factor and interfacial characteristics, the performance of the heat sink can be adjusted for the best performance. The present study will provide helpful guidelines in designing viable heat sinks or exchangers with smart surfaces for electronics cooling and associated applications.

Evaluation of entropy generation characteristics of boehmite-alumina nanofluid with different shapes of nanoparticles in a helical heat sink

Entropy generation characteristics of different nanoparticle shapes are explored considering a nanofluid-cooled helical heat sink system for both laminar and turbulent flow regimes. For each flow regime, four different Reynolds numbers are considered, ranging from Re=500 to 20,000. Five different particle shapes (spherical, bricks, blades, cylindrical and platelets) are included for this comparative study, and their thermal, frictional, and total entropy generation characteristics are evaluated for four different nanoparticle volume concentrations (ϕ=0.5, 1.0, 1.5, and 2.0%), and the outcomes are compared to the base fluid case (ϕ=0%) as well as a comparison is considered among the investigated nanoparticles. Obtained results revealed that in the turbulent flow regime, the thermal entropy generation tends to decrease with increasing particle volume fraction, and the highest decrements are obtained for platelet shape (43%). The frictional entropy generation shows an opposite trend, and the platelet nanoparticles yield the highest increment, around 6.32 folds in both laminar and turbulent flow. In both flow regimes, the spherical particles have the smallest impact on the entropy generation among the examined ones. In addition to that, increment in Re results in a decrement in the thermal entropy generation, while it causes a remarkable increase in the frictional entropy generation.

Performance comparative study of a concentrating photovoltaic/thermal phase change system with different heatsinks

• Performance of concentrating PV/T-PCM system with different heatsinks was compared. • Non-uniformity of PV module temperature dropped by 47%∼82% when PCM melted. • Primary energy-saving efficiency of S-type system was 8% higher than H-type. • Concentrating PV/T-PCM owned superior performance than PV-CPC and PT-CPC system. In this study, a compound parabolic concentrating photovoltaic/thermal phase change system with different heatsinks (S-type and H-type) are constructed in an open-air environment to experimentally analyze the influence on photothermal, photovoltaic and heat-electricity cogeneration performance. The non-uniform irradiance distribution at different moments is simulated with the Monte Carlo rays tracing method, and it is demonstrated to be the main cause of non-uniform temperature distribution on photovoltaic module surface. The H-type heatsink system integrating phase change material (PCM) owns better temperature regulation performance, as its photovoltaic modules temperature and non-uniformity factor are about 0.8 ℃ and 0.05 lower than those of S-type respectively when PCM begins to melt. The instantaneous electrical and thermal efficiency with H-type heatsink are 0.6% higher and 10.0% lower than those with S-type, respectively. Considering that the pump power consumption of S-type heatsink is over 3 times of H-type, the instantaneous priamry energy-saving efficiency of S-type system is 8.0% higher. Simultaneously, the maximum primary energy-saving efficiency of concentrating photovoltaic/thermal phase change system with H-type/S-type heatsink is about 7.9%/14.6% and 10.7%/17.4% higher than that of concentrating photovoltaic and solar collector system respectively, showing great potential of photovoltaic/thermal phase change system in heat-electricity cogeneration performance especially utilizing S-type heatsink. Results present advantages of the system utilizing S-type heatsink and help promote the application of heatsinks in photovoltaic/thermal phase change system.