Innovative Heat Research Articles

Thermal management of honeycomb heat sink filled with phase change material for smart lighting applications

Recently, thermal management of LEDs lamps has become increasingly essential due to the widespread integration of LEDs in smart lighting applications. In this work, we focus on the thermal analysis of convective heat transfer using a honeycomb heat sink designed for LEDs lamp cooling. Three different heat sink geometries were examined: an aluminum-filled honeycomb radiator, a hollow honeycomb radiator, and a hollow honeycomb radiator incorporating a phase change material (PCM) layer. The results obtained from numerical simulations using COMSOL Multiphysics® showed that the third heat sink geometry, when employed in short-duration lighting applications, led to a 25% reduction in temperature for a 20W power lamp. We also determined the optimal operational time, during which the temperature drop is maximum. Moreover, we observed that the integration of a PCM-filled honeycomb radiator in cyclic lighting applications (involving on/off cycles and high/low power settings) significantly mitigates temperature rise in the lamp by leveraging the PCM's heat storage capacity. This approach effectively prevents thermal shocks, ensures prolonged LEDs performance, and contributes to energy savings in the lighting sector. By addressing the thermal management challenges associated with LEDs lamps through innovative heat sink designs and the utilization of PCM, our research offers valuable insights for enhancing the overall performance and efficiency of LED lighting systems.

Efficiency Enhancement in Ocean Thermal Energy Conversion: A Comparative Study of Heat Exchanger Designs for Bi2Te3-Based Thermoelectric Generators.

This research focuses on enhancing the efficiency of Bi2Te3-based thermoelectric generators (TEGs) in ocean thermal energy conversion (OTEC) systems through innovative heat exchanger designs. Our comparative study uses computer simulations to evaluate three types of heat exchangers: cavity, plate-fins, and longitudinal vortex generators (LVGs). We analyze their impact on thermoelectric conversion performance, considering the thermal energy transfer from warm surface seawater to TEGs. The results demonstrate that heat exchangers with plate-fins and LVGs significantly outperform the cavity heat exchanger regarding thermal energy transfer efficiency. Specifically, plate-fins increase TEG output power by approximately 22.92% and enhance thermoelectric conversion efficiency by 38.20%. Similarly, LVGs lead to a 13.02% increase in output power and a 16.83% improvement in conversion efficiency. These advancements are contingent upon specific conditions such as seawater flow rates, fin heights, LVG tilt angles, and locations. The study underscores the importance of optimizing heat exchanger designs in OTEC systems, balancing enhanced heat transfer against the required pump power. Our findings contribute to a broader understanding of materials science in sustainable energy technologies.

Research on Optimization Design Based on Heliostat Field

This study aims to deeply explore the mathematical modeling and performance optimization of solar heliostat fields, in order to improve their energy output efficiency. The solar heliostat field is an innovative solar heating system that focuses solar radiation on the absorption tower through a reflector, thereby generating high-temperature heat energy. This article mainly discusses the performance analysis and parameter optimization of the heliostat field to achieve optimal performance while meeting the rated power requirements. A simulated solar model was established using a three-dimensional Cartesian coordinate system, taking into account the effects of solar altitude angle and direct normal irradiance (DNI). The model in this paper comprehensively considers the effects of shadow occlusion loss, cosine efficiency, atmospheric transmittance, collector truncation efficiency, and mirror reflectance on the mirror field. The specific values of each parameter were calculated using model algorithms such as the HFLCAL model, To provide a basis for accurate performance analysis and solve the problem of parameter optimization, this article defines an objective function aimed at improving the energy utilization efficiency of the heliostat field by adjusting the parameters of the reflector, in order to achieve optimal performance. The above parameters are determined by establishing a genetic algorithm to define constants and initial parameters, and initializing the overall layout of the heliostat field to calculate the optical efficiency of the heliostat. In each iteration, the optimal heliostat field layout can be recorded. The final optimal solution includes parameters such as the position coordinates of the absorption tower, heliostat size, installation height, number of heliostats, and heliostat position.

Thermoelectrocatalysis: an emerging strategy for converting waste heat into chemical energy.

This perspective defines and explores an innovative waste heat harvesting strategy, thermoelectrocatalysis (TECatal), emphasizing materials design and potential applications in clean energy, environmental, and biomedical technologies.

High Temperature Biomass Fired Stirling Engine (HTBS)

Biomass is an important resource for the utilisation of renewable energy not only in Germany, but in many other countries. Being sufficient to provide base load it is capable to stabilise electricity grids besides contributing to climate change precaution. Additionally it is essential that the applications for heat, power and fuel feature high conversion efficiencies. There fore the on-site generation of electricity is a crucial contribution to renewable energy supply, especially in real small-scale applications. The project “HTBioStir” - development of a high temperature heat exchanger for the coupling of biomass boiler and Stirling engine - is designed and realized as a fundamental research project focusing on important mechanisms of heat transfer. The basic approach to generate electricity and heat implies the transfer of enthalpy on high temperature levels from the flue gases of a wood chip operated fire tube boiler to the working fluid helium through the heater head of a Stirling engine generator set. Using an indirect heat transfer mechanism, air as the carrier, an innovative heat exchanger with surface structured industrial power tube bundle and upstream a similar recuperative air-preheater by which an α-type SOLO 2V is operated to gene rate electricity. The leaving air at a much lower temperature level serves then as preheated oxidant in the furnace, while the flue gases produce hot water in the boiler. At present measure ment campaigns were carried out to establish energy and mass balances of the fire tube boiler as well as the Stirling engine.

Power generation analysis of super-long gravity heat pipe geothermal systems

Highly-efficient and environment-benign heat extraction and utilization technologies are key to large-scale geothermal energy deployment. In recent developments, the innovative super-long gravity heat pipe (SLGHP) geothermal power plant has revolutionized deep geothermal power generation by obviating the need of flash devices or heat exchangers in vapor generation for turbine propulsion. This advancement promises substantial structural simplification, a marked reduction in exergy losses, and significant cost savings. Nevertheless, a comprehensive understanding of the performance of SLGHP power generation systems is still lacking in published research. For a single-well geothermal system, the geothermal gradient assumes critical importance as it serves as a key indicator of resource intrinsic conditions, and the depth of the well emerges as an essential controllable variable in manual drilling. The present investigation seeks to elucidate the impact of these two key parameters on the performance of SLGHP power generation systems. For this purpose, a semi-empirical formula is analytically derived to describe the heat extraction process within the SLGHP system. This formula is integrated with a thermo-economic model to evaluate the performance of the SLGHP power generation system. It is found that adjusting the two parameters can yield simultaneous increases in the heat extraction rate and the energy efficiency, thereby resulting in a significant boost in power generation of SLGHP. Specially, the SLGHP system of a 4000 m deep well and with a 0.045 K/m geothermal gradient can output 35.95 kW electricity, while that of a 5000 m deep well and with a 0.05 K/m geothermal gradient achieves 86.39 kW electricity output. In practical terms, it is found that the optimal strategy for an SLGHP power plant involves drilling multiple wells in a reservoir with a higher geothermal gradient. However, when repurposing abandoned oil/gas wells for power generation, the preference is for deep wells.

Thermally enhanced nanocomposite phase change material slurry for solar-thermal energy storage

This paper investigates the photothermal conversion performance of an innovative heat transfer fluid containing nano-encapsulated phase change material (PCM) with metallic shell materials in a solar thermal energy storage system. The influences of shell thickness, core size, shell material type, PCM mass and shell volume concentrations on the thermal performance of the heat storage medium are investigated and compared. The results show that the heat transfer rates of water-based Ag, Au, Cu and Al nanofluids are 6.89, 5.86, 7.05 and 6.99 W, respectively, while slurries formed by adding paraffin@Ag, Au, Cu and Al nano capsules to pure water enhance heat transfer by 6.18, 13.38, 10.8 and 11.33 %, respectively. The metallic nanoparticle-based shell materials further augment the temperature and energy storage gains by enhancing the solar radiation capture capability of the heat storage medium. Specifically, depending on the mass concentration of PCM, the storage capacity of paraffin@Cu slurry is augmented by up to 290 %. As the shell thickness of the Ag particles also decreases from 8 to 2 nm, it augments the slurry's storage ability for thermal energy by 7 %. The enhancement in the dimensions of the nano capsules, however, causes the surface area-to-volume ratio (SA:V) to reduce the photothermal conversion of the slurry by clustering. Therefore, the thermal energy storage behaviour of the Paraffin@Cu slurry is diminished by 5 % as the core size enhances from 10 to 40 nm. Further, the augmentation in the volume concentration of Al particles in the shell surprisingly reduces the thermal energy storage by 5 %. Finally, paraffin-based solid PCM is also experimentally tested for validation of the specific heat capacity model at various wind speeds and solar radiation.

Forced convection analysis of Williamson-based magnetized hybrid nanofluid flow through a porous medium: Nonsimilar modeling

The purpose of this work is to analyze the convective horizontal flow of Williamson-based magnetized hybrid nanofluid. The flow of Williamson fluid with heat transfer is stimulated in a porous media over a stretching surface. Two different type of nanoparticles such as, molybdenum disulfide ( Mo S 2 ) and copper (Cu) with engine oil (Eo) as base fluid are considered in this work. The convective flow of Williamson fluid is inspected based on Khanefer model. The governing system is transformed into nondimensionalized partial differential equations (PDE’s) by utilizing nonsimilar transformation. The transformed system is analytically approximated using local nonsimilarity (LNS) and perturbation approach which approximate the nondimensional PDE’s by nondimensional ordinary differential equations (ODEs). The LNS and perturbation ODEs are simulated utilizing finite difference-based algorithm bvp4c. The outcomes of simulation for heat transfer and convective flow over stretching surface incorporating the evolvement with local Nusselt number (Nu) for distinct values of prandtl number are compared with previous published numerical results. The appropriate range of governing nondimensionalized parameters is evaluated to detect the variance of physical quantities namely, velocity ( f ′ ( η ) ) of the fluid, temperature ( θ ′ ( η ) ) of the fluid, co-efficient of local Nusselt number (Nu) and co-efficient of local skin friction (Cf). The percentage difference between single nano-fluid and hybrid nano-fluids is made which are given in tabular form. To the best of author knowledge, nonosimilar study of hybrid-based magnetized Williamson nanofluid is not yet investigated. This work is anticipated to offer crucial information for the implementation of innovative heat transfer devices in the future and serve as an invaluable resource for researchers looking at the flow of nanofluids under various assumptions.

Advancing thermal management in electronics: a review of innovative heat sink designs and optimization techniques.

The ongoing trend towards miniaturizing electronic devices and increasing their power densities has created substantial challenges in managing the heat they produce. Traditional heat sink designs often fall short of meeting modern electronics' rigorous thermal management needs. As a result, researchers and engineers are turning to innovative heat sink designs and optimization methods to improve thermal performance. This review article offers an overview of the latest advancements in designing and optimising advanced heat sinks for electronic cooling. It explores various techniques to enhance heat transfer, including advanced surface geometries and microchannels. Additionally, the review covers computational fluid dynamics (CFD) modelling and experimental validation methods used to refine heat sink designs. Further insight into fouling and its prevention has been discussed. The insights provided in this article are intended to serve as a valuable resource for thermal engineers, and researchers focused on managing the heat in high-power electronic systems.

Sensitivity analysis of the thermal performance of a parabolic trough concentrator using Al2O3 and SiO2/Vegetable oil as heat transfer fluid

This paper aims to highlight the use of different heat transfer fluid (HTF) configurations based on vegetable oils in Parabolic Trough Solar Concentrator (PTSC). Rapeseed and jatropha oils as innovative heat transfer materials combined with SiO2 and Al2O3 to obtain six (6) HTF configurations are used in a 1-dimensional PTSC model. The thermophysical properties of the nanofluids are determined from correlations derived from the literature, using Gauss-Seidel method from a numerical code developed in Matlab software. Model validation is obtained. Thermal sensitivity analysis shows that the use of rapeseed increases the thermal efficiency of the PTSC by around 4.21 % compared with jatropha. The use of nanofluids reduces thermal losses within the system due to thermal gradients. For a fixed irradiance and each 1 %–4 % increase in volume fraction, thermal efficiency increases by around 1.96 % when Al2O3/rapeseed is used and by 0.47 % when SiO2/rapeseed is used compared with rapeseed. Similarly, thermal efficiency increases by around 1.98 % when Al2O3/jatropha is used and decreases by around 0.20 % when SiO2/jatropha is used compared with jatropha. However, the positive effects of nanoparticles on thermal conductivity alone are not always sufficient to improve thermal efficiency, and thermal effects on heat capacity should also be considered.

A novel Ground Source heat exchanger in an underground metro tunnel

Using Ground Coupled Heat Pump (GCHP) systems in urban areas can be particularly difficult due to space or legislative constraints, other than excessive costs due to drilling. To overcome these problems, the authors proposed to use Artificial Ground Freezing (AGF) probes, used for tunnel excavation, as Ground Heat Exchangers (GHE). It is a widespread practice to seal the probes in the tunnel after the completion. The conversion of existing AGF probes into GHE for GCHP allows us to avoid additional drilling costs, and other space or legislative constraints associated with the use of GCHP systems in urban areas. Such systems could be developed to use underground urban transportation tunnels for heating and cooling in smart cities. These systems were tested after the construction of two tunnels, as part of the GeoGRID project, in Piazza Municipio, Naples, Italy. The data obtained from the experimental setup have been analysed and used for validation of a finite element model developed by the authors to simulate heat transfer between the probes and the surrounding ground. A simplified pipe flow model was introduced, in combination with a 3D model of the ground, to reduce the complexity and computational effort to solve the discretized equations. The simulation results have been compared with experimental data, showing a good agreement, and observing differences in the range of 2 – 5 %. The model can therefore be used as a predictive tool for the development of this type of innovative heat exchanger.

Willingness to pay for innovative heating/cooling systems: A comprehensive appraisal of drivers and barriers to adoption in Ireland and Italy

This paper investigates drivers or hindrances to households' adoption of behavioural changes concerning energy efficiency at home. A Choice Experiment survey has been conducted to elicit households’ preferences regarding adoption of innovative heating/cooling systems in Ireland and Italy. The choice data is analysed through a Latent Class model, and posterior analysis is used for class profiling, aimed to detect the emergence of factors identified in the literature. In both country samples respondents could be grouped in three classes according to their preferences and willingness to pay for adoption of innovative heat pump systems. Early adopters, younger and with higher education, exhibit strong pro-innovation attitudes. Conversely, Laggards, typically older and less educated, display hesitancy, and may require substantial subsidies for adoption. Late adopters value trialability and rely less on social networks. Information processing varies according to individual capabilities and social contexts. Hence, we recommend targeted information to enhance awareness of benefits and on feasibility of installation in different types of dwelling. Technical information and support, possibly complemented by demonstration activities, is suggested to foster innovation, especially among less advantaged households.

Investigation of novel pulse preheating strategies for lithium-ion batteries at subzero temperature based on a multi-level CFD platform

Warming up lithium-ion batteries from cold environments to room temperature rapidly and safely is the key to popularizing battery electric vehicles in cold regions. Pulse preheating technology is an effective internal heating method while facing challenges such as low heating rate, high energy consumption, and risk of over-charging or discharging. Here, for the first time, a multi-level electrochemical-thermal coupling model is developed on an open-source CFD platform. Based on this model, we perform comprehensive simulations for the pulse heating process with various parameters and strategies from plate level to cell level to module level. In addition, two innovative heating strategies, namely varied rate pulse and hybrid pulse, are proposed, where the latter integrates the pulse heating and electric heating. Our main results show that the proposed hybrid pulse strategy can provide cells with an over 2.5 times faster heating rate from −20 °C to 0 °C and save nearly 60 % energy consumption compared to the single pulse heating at 6 C-rate, exhibiting a great prospect in circumventing the low-temperature effect. Besides, the internal temperature difference can be controlled. A high pulse frequency is suggested to achieve better temperature consistency within cells and avoid noticeable changes in the cell internal physical fields.

Technological Improvement of the Panela Packaging Process Using a Heat Recovery and Heat Sealing System

In the context of panela processing and its technological improvement, this article addresses the implementation of technological enhancements in the packaging process by incorporating a heat recovery system and developing a heat sealing tunnel. The study aims not only to enhance the efficiency of the packaging process but also to reduce energy consumption and improve the quality of the end product. Regarding the methods, a detailed analysis of heat loss during panela production was conducted, and a heat recovery system was designed to harness this energy. Furthermore, an energy analysis of the panela production plant was initially carried out to determine the appropriate point for implementing the recovery system. Based on this information, an innovative heat sealing tunnel was developed to ensure the packaging quality of the product, working from the mechatronic design perspective.In terms of results, the energy efficiency of the plant was identified, along with a notable improvement in energy efficiency in heat recovery, directing it towards the heat sealing system. This, in turn, had a positive influence on the quality of the packaged panela, thanks to the proper sealing provided by the new heat sealing tunnel. In conclusion, this study demonstrates that the combination of heat recovery and heat sealing technologies has a significant impact on the efficiency and quality of the panela packaging process in terms of sustainability and process improvement.

Implicit Finite Difference Simulation of Hybrid Nanofluid along a Vertical Thin Cylinder with Sinusoidal Wall Heat Flux under the Effects of Magnetic Field

A numerical analysis of magnetohydrodynamic natural convection along a thin vertical cylinder with a sinusoidal heat flux at the wall immersed in copper (Cu) and aluminum-oxide (Al2O3) hybrid nanofluids has been studied. A 2D vertical thin cylinder shape geometry has been considered with a radius of R. The fluid flow is considered laminar and incompressible with the Prandtl number of Pr = 6.2 and 10% concentration of hybrid nanoparticles. The nondimensional governing equations have been solved numerically by using the implicit finite difference method. An in-house FORTRAN 90 code is used for solving this problem and the code is validated with the available benchmark results. Numerical simulations have been performed for a wide range of governing parameters, Hartmann number from Ha = 0 to Ha = 4, nanoparticles volume fractions ϕ = 0.0 to ϕ = 0.1, and the amplitude of the wall heat flux ε = 0.0–0.3. The findings have been illustrated in terms of streamlines, isotherms, local skin friction coefficients, local Nusselt numbers, velocity, and temperature distributions. The flow field and temperature distribution within the boundary layer are deceased by the effects of the wall heat flux amplitudes. It is also noted that the rate of heat transfer increases with particle volume fraction and the amplitude of the wall heat flux. According to the findings, Nu increases by 24.72% as ϕ increases from 0 to 0.1 while ε = 0.3, and 27.66% while ε increases from 0.0 to 0.3 at 5% hybrid nanoparticles. The local skin frictions and Nusselt number diminish with the increment of the Hartman number due to the effects of the Lorenz force. The findings of this study can lead to a better understanding of the fundamental principles regarding the behavior of hybrid nanofluids under complex conditions, such as a vertical thin cylinder with a sinusoidal wall heat flux. Understanding the behavior of hybrid nanofluids in the presence of a magnetic field and a nonuniform wall heat flow can also lead to the development of innovative heat transfer enhancement strategies.

ELSMOR European Project: Experimental Results on an Innovative Decay Heat Removal System Based on a Plate-Type Heat Exchanger

This paper summarises the results of an experimental campaign carried out at SIET on the ELSMOR facility built in 2022 to validate a decay heat removal system for the E-SMR. Based on the passive mechanisms of natural circulation, the system aims to dissipate the reactor decay heat to a water pool, using two heat exchangers: a plate-type one coupling the primary side to the secondary side, and a vertical tube one coupling the secondary side to the water pool. Such a system is considered to be the most effective passive system, capable of safely managing the SMR accident and accidental situations, and achieving long-term decay heat removal without the need for electricity or external inputs. A description of the primary and secondary loops of the plant is given, together with the installed instrumentation and data acquisition system. In addition, the paper summarises the tests performed in terms of test procedures, test type and associated objectives, test matrix, test results, achievements, and open issues.

Performance investigation of a novel low-carbon solar-assisted multi-source heat pump heating system demonstrated in a public building in Hull

Global climate change has raised great attention from governments and prompted a wave of application of low-carbon heating technologies. However, solar-assisted heat pump, as an attractive technology, has challenges of unstable performance and complex structure and control strategy in practical application. Following the carbon-neutral strategy, a novel low-carbon solar-assisted multi-source heat pump heating system (LSMHS) is therefore proposed to improve the application potential of SAHP, which is demonstrated in Hull Central Library by replacing the library's original gas boiler heating system (GBHS). The LSMHS integrates eight novel multi-throughout-flowing solar collector arrays with an innovative two-stage heat recovery heat pump which can automatically switch different operation modes according to weather conditions. The practical operation results revealed that the LSMHS maximized the advantages of each component and achieved a high monthly average system COPsys ranging from 2.12 to 2.68 in the three-month demonstration. Eventually, the LSMHS provided a bill saving of 0.73 % with a significant carbon reduction of 63.69 % when compared to the GBHS in practice, achieving an equivalent bill saving of £6.7 for every tone of carbon reduction. The remarkable demonstration results showcased the application potential of the novel LSMHS and gave valuable guidance for low-carbon building heating.

Performance evaluation and multi-objective optimization of an innovative double-stage thermoelectric heat storage system for electricity generation

As the need for renewable energy continues to grow, there is an increasing requirement to utilize systems that offer enhanced performance and efficiency. Consequently, a comprehensive investigation is conducted on a two-stage thermoelectric heat pump. The primary objective is to assess the impact of various influential factors on the overall effectiveness of the system. This exhaustive parametric study aims to provide valuable insights into the system's performance and efficiency. Subsequently, the multi-objective optimization approach considers both technical and economic goal functions. By incorporating these two aspects, the optimization process seeks to achieve the most favorable balance between technical performance and economic feasibility. This allows for a holistic assessment that takes into consideration not only the system's efficiency and effectiveness but also its economic viability in real-world applications. The best optimal solution is discovered using a variety of methods for multi-objective optimization. The optimized system is examined from both an exergy and an exergoeconomic vantage point after the best optimal solution has been identified by comparing the results of various methodologies. The outcomes demonstrate that for the multidimensional analysis of Linmap, the combination of multi-objective particle swarm optimization (MOPSO) and the linear programming technique yields the best optimal solution. The objective functions for this final optimal solution are unit cost of heating power and exergy efficiency, which are defined as 1.91 and 51.28 USD/(kWh), respectively. The results showed that the optimal current for temperature changes of 10, 20, and 30 K is 2.84, 5.53, and 8.1 respectively. Also, the optimal length and number of thermocouples were 0.0055 m, 30, and 15 m respectively in all techniques. The optimal current changes from 23.30 to 27.60 A, which indicates that the optimization technique prefers to adjust the current over other effective parameters. When the thermocouples in the first and second stages are 30 and 15 pairs, respectively, according to the design parameters of the ideal point, the system will work at its peak efficiency.

Environmental sustainability by an integrated system based on municipal solid waste fluidized bed gasification using energy, exergy, and environmental analyses

As an eco-friendly method of waste disposal, municipal solid waste (MSW)-to-multi-generation energy systems based on gasification reduces the amount of waste sent to landfills, generates clean energy that can be used to power homes and businesses, reduces our reliance on fossil fuels, and helps to reduce greenhouse gas emissions. In this study, a novel system is developed based on MSW gasification by combining a fluidized bed gasifier, a solid oxide fuel cell (SOFC), and a heat recovery to produce heat and power. In-depth research is done on the power output, heating capacity, energy and exergy efficiencies, and emissions of this innovative combined heating and power system. Electrical and exergy efficiencies of the system are improved with the steam to MSW ratio from 40.6 % to 41.4 % and from 36.4 % to 37.0 %, respectively, and the emission is reduced. Increasing utilization factor enhances electrical (from 37.2 % to 44.4 %) and exergy (from 33.4 % to 39.6 %) efficiencies and declines the emission (from 955.2 to 800.7 kg/MW.s). Decreasing current density and increasing SOFC temperature boost the system performance from energy, exergy, and environmental viewpoints. The future of multi-generation energy systems based on MSW gasification looks bright, as they offer a sustainable way to manage waste while meeting the growing demand for clean energy.

Heat pump supply chain environmental impact reduction to improve the UK energy sustainability, resiliency and security

Various heat pump technologies are examined from an environmental perspective using a life cycle assessment approach. The investigated heat pump systems utilize air, ground, and water as their energy sources. Additionally, an innovative heat pump powered by green hydrogen is investigated in this study, to evaluate its environmental impacts and potential to commercialise on a large scale. A range of supply chain scenarios is explored, considering the main suppliers of the UK market. The reshoring heat pump industry and supply chain are evaluated to enhance energy resilience and security within the UK. The findings indicate that the hydrogen-based heat pump presents a promising option for the UK market, offering the advantages of reducing stress on the national grid network and minimizing the environmental impacts associated with the supply chain. Furthermore, a forecasting analysis is conducted based on the UK's net-zero emission plan to provide insight into future developments.