Heat Transfer Area Research Articles

Development and optimization of dual-objective PVT modules for a smart residential building using inclined fins

According to the sustainable development strategy, air-based photovoltaic-thermal (PVT) modules integrated with smart buildings are an effective and environmentally safe option for producing electricity and heating purposes to overcome the problem of scarcity and environmental pollution resulting from fossil fuels. Despite the importance of PVT modules, this technology has not achieved the required diffusion rates compared to other solar energy technologies due to its low overall efficiency. Therefore, the present study aims to develop the design of a heat transfer system integrated with PVT modules. To achieve this goal, the design of a heat transfer system was developed by adding 45° inclined fins integrated with the cooling channel to generate swirling movement near the back surface of PVT modules and increase the heat transfer area. To illustrate the best location for installing 45° inclined fins that achieve the highest performance improvement of PVT modules, we suggested two positions for installing 45° inclined fins and compared them with the dual-objective classical PVT modules (DO-CPVT) without fins. The first case is dual-objective PVT modules with top-inclined fins (DO-PVT&TIF). The second case is the dual-objective PVT modules with bottom-inclined fins (DO-PVT&BIF). The results presented that, dual-objective PVT modules with top-inclined fins (DO-PVT&TIF) represent a good design that achieves the highest performance. The improvement in thermal efficiency, electricity generation, overall energy efficiency, total exergy efficiency, and sustainability index for using DO-PVT&TIF modules reached 231 %, 11.5 %, 133.8 %, 19.3 %, and 4.3 %, respectively compared to classical DO-CPVT.

Simulation of continuous thermally regenerative electrochemical flow cycle and coupled with photovoltaic/thermal system

Thermally regenerative electrochemical cycle (TREC) is an efficient, clean and feasible low-temperature thermoelectric conversion technology. Coupling it with flow battery (FB) can not only achieve continuous operation, but also can be used to realize the heat energy recovery of the photovoltaic/thermal (PV/T) system. In this paper, a continuous TREC-FB system including two charging-free cells is proposed for outputting power at both high and low temperatures. An electrochemical-thermodynamic coupling algebraic model is established to explore the effects of electrolyte flow rate, temperature difference and design parameters of heat exchanger on the power density (PTREC) and thermoelectric efficiency (ηele,TREC) of the TREC-FB. Experimental study on TREC-FB is carried out for model validation. The results show that PTREC is determined by the temperature difference and the electrolyte flow rate, which contribute to enhanced voltage and mass transfer, respectively. For specific heat source scenarios, the ηele,TREC is mainly affected by the flow rate, followed by the heat transfer area AH, and finally is the flow channel height and the thermal conductivity of the heat exchanger. Moreover, for the continuous TREC-FB-PV/T coupled system, the energy conversion efficiency reaches an average of 11 % within one day by optimizing the designed temperature difference.

Effect of charcoal balls on distillation productivity in hemispherical solar stills: Experimental investigation and performance analysis

This study investigates the enhanced performance of hemispherical solar stills by integrating charcoal balls. The method showcases improved efficiency by augmenting heat transfer mechanisms and enhancing solar radiation absorption. Reducing the surface tension of basin water is a solution to increase its heating, enhancing the softwater yield of solar stills. The novelty of the research lies in the innovative integration of charcoal balls to improve the performance of hemispherical solar stills. This method presents a unique approach to enhancing heat transfer and evaporation dynamics, potentially revolutionizing the efficiency of solar desalination systems. Therefore, the impact of charcoal balls at a diameter of 1 cm on the performance of distillation productivity was studied. A hemispherical solar still containing charcoal balls (HSS-CB) was compared with a simple hemispherical solar still (SHSS) in the same conditions. Experiments were conducted at El-Oued-Algeria in June 2024. The method employed in this research offers distinct advantages, primarily in its ability to enhance solar still efficiency by incorporating charcoal balls. These advantages stem from the increased surface area for heat transfer, improved solar radiation absorption, and potential enhancement of evaporation and condensation processes. Cumulative return results for SHSS and HSS-CB are 4.80 and 6.20 L/m2/day, respectively. The rate of improvement in the cumulative return was 29.16 % for SHSS using the quantity of coal powder. It is recommended that charcoal balls be used to boost solar stills productivity.

Achieving high-thermal-conductivity brazed joint between carbon-based composites and Mo-Cu alloys by increasing the heat transfer area

Carbon-fiber-reinforced carbon matrix (Cf/C)-Mo30Cu brazed joints play an important role in the cooling systems of thermonuclear reactors. However, the limited contact area of heterogeneous interfaces severely limits the heat transfer efficiency. To overcome this drawback, we prepare three-dimensional porous interfaces by pre-oxidizing the Cf/C composite. Results show that circular gaps are formed between the carbon fibers and the pyrolyzed carbon after pre-oxidization at 600 °C in air. Fster braze penetration in the Cf/C composite is achieved, and the heat-transfer area across the interface is dramatically increased. The room-temperature thermal conductivity of the joints reaches a maximum value of 146 W·m−1·K−1 at a pre-oxidation time of 2 min; this value is 30 % higher than that obtained without treatment. The enhancement in thermal conductivity is mainly attributed to the increased contact area at the interface between the brazing seam and the Cf/C matrix, which provides more channels for heat transfer. This method of significantly improving the thermal conductivity is an important guide for the thermal management of thermonuclear reactors.

SiO2 aerogel modified aggregates: Preparation, heat resistance and improvement mechanism

Modification of natural aggregates using SiO2 aerogel solution can not only radically reduce the rutting disease of asphalt pavement, but also avoid the problems of poor heat-resistant performance, mechanical strength and durability of ordinary heat-resistant aggregates. The effects of SiO2 aerogel solution type, modification method and SiO2 aerogel solution dosage on the thermal resistance and adhesion properties of SiO2 aerogel-modified aggregates (SM-Agg) were explored by orthogonal tests. Based on scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and infrared thermography, the surface micromorphology, elemental composition and dynamic thermal resistance properties of natural aggregate and SM-Agg were analyzed, respectively. The results showed that Both SiO2 aerogel solution type and dosage significantly affect the evaluation indexes and the modification of natural aggregates by soaking method using ZN-S type SiO2 aerogel solution with 15 % of the aggregate mass could obtain SM-Agg with good heat resistance and adhesion properties. The surface of SM-Agg was covered with a “gel layer” containing uniform and densely distributed SiO2 aerogel particles. The temperature of the top surface of the 18.3-mm-thick SM-Agg specimen gradually changed from 2.2°C higher than that of the natural aggregate to about 1.8°C lower than that of the natural aggregate within 60 min of heating at 55°C. The “gel layer” containing SiO2 aerogel particles forms one or more layers of three-dimensional heat-blocking mesh on the aggregate surface, which dramatically reduces the heat transfer area, prolongs the heat transfer path within the specimen, and increases the heat-reflecting capacity of the aggregate surface.

Performance Analysis and Rapid Optimization of Vehicle ORC Systems Based on Numerical Simulation and Machine Learning

The organic Rankine cycle (ORC) system is an important technology for recovering energy from the waste heat of internal combustion engines, which is of significant importance for the improvement of fuel utilization. This study analyses the performance of vehicle ORC systems and proposes a rapid optimization method for enhancing vehicle ORC performance. This study constructed a numerical simulation model of an internal combustion engine-ORC waste heat recovery system based on GT-Suite software v2016. The impact of key operating parameters on the performance of two organic Rankine cycles: the simple organic Rankine cycle (SORC) and the recuperative organic Rankine cycle (RORC) was investigated. In order to facilitate real-time prediction and optimization of system performance, a data-driven rapid prediction model of the performance of the waste heat recovery system was constructed based on an artificial neural network. Meanwhile, the NSGA-II multi-objective algorithm was used to investigate the competitive relationship between different performance objective functions. Furthermore, the optimal operating parameters of the system were determined by utilizing the TOPSIS method. The results demonstrate that the highest thermal efficiencies of the SORC and RORC are 6.21% and 8.61%, respectively, the highest power outputs per unit heat transfer area (POPAs) are 6.98 kW/m2 and 8.99 kW/m2, respectively, the lowest unit electricity production costs (EPC) are 7.22 × 10−2 USD/kWh and 3.15 × 10−2 USD/kWh, respectively, and the lowest CO2 emissions are 2.85 ton CO2,eq and 3.11 ton CO2,eq, respectively. The optimization results show that the RORC exhibits superior thermodynamic and economic performance in comparison to the SORC, yet inferior environmental performance.

Experimental study of the optimal design and performance of a mixed-flow dew-point indirect evaporative cooler

Evaporative cooling technologies represent a promising alternative to face the emerging cooling energy poverty, owing to their low production and operative costs. High performance can be achieved through more complex designs, such as dew point indirect evaporative cooling (DIEC) systems. Recent literature explores improvements on these systems, like flow configuration, materials, and water distribution. This study proposes a compact mixed-flow DIEC system made of polycarbonate plates covered with two possible wicking materials. Three water distribution systems are also studied. The prototypes are experimentally characterised by varying the inlet air temperature, humidity, volume flow, and working-to-intake air ratio. The best performing design is evaluated in terms of temperature drop, dew-point effectiveness, wet-bulb effectiveness, and cooling capacity. Results are consistent with those in the literature for equivalent heat transfer areas. The use of a wicking material improves the cooling capacity by up to 1.45. The type of material is less relevant, which enables to select the most economic and accessible option. External nozzles for water distribution offers temperature drops of more than 1 °C and better cooling capacities of approximately 100 W than inlet water distributors.

Design optimization of shell and tube type heat exchanger of G.A Siwabessy multi-purpose reactor cooling system

G.A Siwabessy multi-purpose reactor is a nuclear reactor that utilizes a controlled fission reaction (a chain reaction of atomic fission). The heat exchanger in the reactor cooling system plays a vital role in transfering heat from the primary coolant side to the secondary coolant side. Heat transfer coefficient (U) and heat transfer area (Ao) are two variables that have a huge influence on the success of heat transfer in a heat exchanger. The aim of this research is to compare the U and A values in two different ways, namely the full factorial method and the use of Heat Transfer Research Inc. (HTRI) software. The novelty of this research is the use of two different methods to check the U and A0 values of heat exchangers in nuclear reactors. In the calculation using the full factorial method, 4 independent variables with 3 levels were made, so 81 calculations were obtained. The most optimal calculation results are then validated with HTRI software. From the calculation results, it is known that the largest overall heat transfer coefficient (U) is 6531.60 W/m2 °C with a heat transfer area (Ao) of 584.47 m2 . The results of the validation with the HTRI software obtained an overall heat transfer coefficient (U) of 5045.10 W/m2 °C with a heat transfer area (Ao) of 574.19 m2 . There is a difference in value between the results of manual calculations and the results of the validations of the HTRI software which is made possible by a decrease in the performance of the heat exchanger.

Unsteady-state modeling and analysis of a spray-assisted low-temperature desalination system

The spray-assisted low-temperature desalination (SLTD) technology driven by low-grade heat sources has demonstrated excellent thermodynamic and economic performances. However, existing studies are based on steady-state analyses and cannot describe dynamic system performance under fluctuations of the operating conditions. This work presents an unsteady-state analysis of the SLTD system driven by low-grade waste-heat sources. A dynamic model is developed and validated against experimental data. The model is observed to predict dynamic temperature profiles accurately with a maximum absolute error of ±0.3 °C. Then, the model is applied to analyze the responses of the SLTD system to different disturbances. Results show that the first evaporator is the most sensitive to the heat source temperature fluctuation, while locations farther away from the disturbance have longer response times and smaller fluctuations. When the heat source temperature for a 4-effect system fluctuates by 10 %, the response time and temperature fluctuation amplitude of the 1st effect are 579 s and 8 %, respectively, while those of the 4th effect are 1007 s and 3 %, respectively. Besides, the systems with smaller heat transfer areas, fewer numbers of effect, and higher heat source temperatures have faster response speeds. The results provide useful information for system operation and control strategy exploitation.

Large eddy simulation of turbulent transport and thermal enhancement in a steam-cooled ribbed channel

Pulsating flow, as an active heat transfer enhancement technique, is expected to further improve thermal performance. To demonstrate the potential value of pulsating flow in blade cooling, a numerical investigation is conducted on the flow and heat transfer in a steam-cooled ribbed channel under steady and pulsating inflow at Re = 12000. LES, based on OpenFOAM-8, is employed and precursor simulation method is used to generate fully developed turbulent inflow. Three operating conditions, steady inflow (StF = 0), low frequency pulsation (StF = 0.02) and medium frequency pulsation (StF = 0.08), are studied. The features under steady inflow condition (StF = 0) are firstly discussed, indicating that, due to the entry effect, the ribbed channel can be divided into two regions with different vortex motion behaviors. The ejections induced by vortex evolution enhance turbulent and energy transport between the sidewall and mainstream. Two cases of pulsating inflow are then carried out, finding that stronger ejections appear and low heat transfer area is significantly improved. Corresponding to low frequency pulsation (StF = 0.02) and medium frequency pulsation (StF = 0.08), the Nusselt number has an increase of 3.511 % and 14.242 %, respectively, and friction factor has a rise of 3.934 % and 8.253 %, compared with steady inflow. The thermal performance factor is increased by 11.262 % at StF = 0.08, indicating better cooling performance than the rise of 2.188 % at StF = 0.02. It is suggested that pulsating flow with medium frequency pulsation has positive performance in a steam-cooled ribbed channel.

Effect of partition arrangement of metal hydrides and phase change materials on hydrogen absorption performance in the metal hydride reactor

Metal hydride (MH) suffers from strong thermal effects during hydrogen absorption. To fully utilize the reaction heat during hydrogen absorption, phase change material (PCM) can be used to achieve efficient thermal management in the reactor. A novel MH-PCM reactor with the partition arrangement of MH and PCM was proposed in this paper. Then, the two-dimensional multiphysics coupled model of the reactor was developed, and the effects of the number of partitions n, the mass of PCM and the hydrogen absorption pressure Pa on the hydrogen absorption performance were discussed detailedly. The results indicated that the novel MH-PCM reactor not only increases the heat transfer area and boots the hydrogen absorption rate, but also improves the uniformity of temperature distribution. As the n increases from 2 to 5, the hydrogen absorption time gradually shortens. Compared to the conventional MH-PCM reactor, the time for 90% hydrogen absorption shortens by 67.13%. Furthermore, the hydrogen absorption rate can be enhanced with the increasing mass of PCM and Pa. However, the larger these values are, the weaker the enhancement effect becomes. The results of this paper may provide a new direction for the optimized design and engineering application of MH-PCM reactors.

Parametric analysis of working fluid selection for closed-cycle turbo-refrigerators for deep freezing applications

Working fluid selection for closed-cycle turbo-refrigerators (CCTRs) for deep freezing, as a more fundamental topic, has not yet received careful consideration, leading to limitations in attempts to optimizing CCTR design in the early stages of cycle design. This paper proposed the working fluid selection criteria that to select the one leading to the lowest system weight and volume without compromising the system energy efficiency. Design criteria, such as specific speed and Reynolds number, and their dependence on fluid properties are introduced to ensure uncompromising-efficiency design of turbomachinery. Normalized heat transfer area of recuperator correlated with fluid properties is derived as the evaluation criterion for system weight and volume. Applying the proposed criteria, the comparison between potential pure gases shows the normalized heat transfer areas required for nitrogen, neon, and argon are 1, 1.54 and 2.18, respectively. Therefore, nitrogen among all pure gases has the greatest potential to reduce system weight and volume. The comparison among potential binary mixtures highlights the methane-nitrogen mixture with the molar mass of 24.1 g/mol which reduces the required heat transfer area by approximately 20 % compared to pure-nitrogen-based system and may reduce it by nearly up to 30 % for systems with larger cooling capacity levels.

Numerical investigation on heat transfer and pressure drop characteristics of Micro-Pillar array surface

The array surface structure can improve heat transfer efficiency and achieve large heat transfer area per unit of volume. In this study, a numerical simulation using CFD method was carried out to construct a dual-channel three-dimensional mathematical model with micro-pillar array surface. The characteristic of heat transfer and flow resistance for the arrayed surface structure have been studied. In addition, four different array configurations, including cylindrical, elliptical, quadrangular and herringbone, were considered to compare the thermal performance and flow behavior. The configuration with the best overall performance was obtained as cylindrical by comparison. The effects of different heights, arrangement methods and pitches on the system performance were analyzed. The velocity distribution on the array surface was also obtained. It is found that the cylindrical array structure has obvious advantages in overall performance, with more uniform surface velocity distribution and better overall performance at lower Re conditions.

Experimental and numerical investigation of heat sinks constructed by anisotropic 3-D Turing patterns

Heat dissipation is a critical issue for various engineering applications such as electronic devices, turbine blades and batteries. Existing heat sink structures contained inherent shortages in geometric flexibility which prevented further development of heat dissipation technologies. This study proposed a self-organized design method for heat sinks inspired by Turing Patterns (TP) in nature morphogenesis. The biomimetic structures were parametrically controlled with the aid of reaction-diffusion equations in terms of feature size, feature density, structural morphology and structural orientation. The metallic selective laser melting (SLM) technology was adopted to fabricate the three-dimensional (3-D) heat sinks. Experimental and numerical evaluations were conducted to compare TP structures with traditional pin-fin (PF) arrays baselines. Results showed substantial advantages of the TP structures in regulating flow field and enhancing height-wise fluid mixing. The thermal performance factor (TPF) of TP structures is approximately 45 % higher than traditional PF structures with similar feature sizes. The globally averaged magnitude of height-wise velocities of TP structure is around 2.4 times larger than that of PF structures due to the existence of the threshold-like and bridge-like structures. With the aid of three-dimensional structures, full utilization of the coolant was achieved to further increase the heat transfer intensity, while a high synergic level was formed within the flow field and temperature field to reduce the pressure drop. The design method proposed in this study demonstrated strong capability in tuning three-dimensional flow field and is expected to provide new insights to the heat transfer area that faces nonuniform thermal conditions and inhomogeneous flow conditions.

Optimizing thermal efficiency: Advancements in flat plate heat exchanger performance through baffle integration

Compact heat exchangers have been gaining popularity in many industrial applications. Various types of passive turbulising structures such as corrugations, protrusions and ribs are introduced in the flow path to increase the effective heat transfer area and the level of turbulence in the flow path. This study investigates the impact of introduction of baffles on the performance of PHEs in terms of flow characteristics, pressure drop, and heat transfer. Two distinct types of baffle structures, namely wedge and aerofoil configurations, were introduced at varying numbers - 1, 3, and 5. An extensive experimentation is conducted for a FPHE in a thermal power plant of 500 × 2 MW and various flow and thermal parameters are measured. Computational Fluid Dynamics is utilized in this study to find the optimum baffle configuration. A detailed validation study is executed to obtain the correct computational algorithm, that is the right mesh count, optimum turbulence model, and precise numerical algorithm by comparing the numerical results with the available experimental results. Wedge- type baffles create increased turbulence and pressure drop, while aerofoil-type baffles minimize stagnation and exhibit lower pressure drop. Both baffle configurations lead to a substantial increase in heat transfer, with the 5-wedge-baffle setup showing the highest up to a 55% enhancement of Nusselt number. The Performance Evaluation Criterion (PEC) of wedge and aerofoil type is about 1.24 to 1.3 and 1.22 to 1.24 to that of conventional one respectively.

Heat transfer augmentation in heat sink with fin-bars inserted in cooling channel

Adding obstacles and obstructing fluid flow in cooling channel to induce whirl velocity enhances thermal performance in heat sinks. An analysis is presented of conjugate heat transfer in a heat sink with transversely inserted bars in the flow channel. The numerical study seeks to maximise the dimensionless thermal conductance subject to constant total volume. The study contrasts a standard heat sink without a bar with cooling channel inserts with one, two, three, and 4 bars. To improve the surface area for heat transfer, the extended surfaces are placed longitudinally at various points in the cooling channel. A high-density heat flux is applied at the bottom wall of the heat sink and coolant with an inlet velocity vin between 4.26 and 7.26 m/s is pumped in a forced convective laminar condition to eliminate the heat. A computational fluid dynamic (CFD) code incorporated in Ansys fluent is used to solve the mathematical models. The numerical analysis indicates that the configuration featuring 3 bars inserted at the roof of the cooling channel exhibits the highest global thermal conductance, achieving a 53 % increase over other configurations. All configurations with 3 bars inserted up, down, left and right, maintain a constant pump power of 3.5 W across a Reynolds number range of 857–1461. Bars positioned at the roof of the cooling channel experience the lowest outlet and inner wall temperatures, whereas those at the floor exhibit the highest temperatures. The optimised design meets the highest porosity limit of 0.8.

CFD modeling of a mini-pilot scale CO2 hydrogenation to hydrocarbons reactor using both direct and indirect pathway-based kinetic model

Both indirect CO2 hydrogenation (reverse water gas shift (RWGS) followed by CO-based Fischer-Tropsch synthesis (FTS)) and direct CO2-based FTS were considered for CO2 hydrogenation, and a kinetic model for the chain-length distribution of hydrocarbon products was developed. For independent estimation, the kinetic parameters were estimated by fitting the experimental data using powder catalysts under various conditions, mainly including CO/CO2 ratios. The contribution of indirect CO2 hydrogenation (RWGS followed by CO-FTS) was more favorable than that of direct CO2-FTS, and CO2 conversion and product selectivity were significantly dependent on the temperature and hydrogen fraction. The effectiveness factor was estimated for the pellet-type catalysts, and values less than one validated the existence of mass-transfer resistance. Computational fluid dynamics (CFD) modeling was used to simulate the three-dimensional thermal behaviors of a mini-pilot-scale reactor with a substantially large diameter loaded with a pellet-type catalyst and inert materials. Both a low catalyst loading in the early stage of the reactor and the use of an additional inner cooling tube showed a stable temperature profile, with the peak temperature maintained below 350 °C (the critical temperature to prevent the thermal decomposition of chemicals) and fast heating of cold feed in the early stage. The CFD results with no inner tube showed thermal runaway in the second reactor, and the simulation with arbitrarily reduced heat of the reaction (70 % of the actual value) resulted in a peak temperature higher than 410 °C. Further quantitative analysis indicated that the no-inner-tube case's reduced heat transfer area per unit volume was responsible for its thermally unstable behavior.

Effect of Chevron Angles on the Thermal Performance of Corrugated Plate Heat Exchanger (CPHEs)

Corrugated plate heat exchangers (CPHEs) possess a greater surface area for heat transfer and a heightened level of turbulence as a result of the corrugations. This study presents an experimental analysis comparing the thermal performance of a flat plate heat exchanger and a corrugated plate heat exchanger (CPHE) with varied corrugation angles. The analysis was conducted using water as the test fluid. The comprehensive testing has been carried out on CPHEs with different chevron angles (β) of 30°/30°, 45°/45°, and 60°/60°. Experimental data is collected under steady- state conditions, with a single phase (water-water) system, covering Reynolds numbers (Re) ranging from 900 to 1250. The test fluid's mass flow rate, ranging from 0.05 to 0.16 kilograms per second, is measured together with the accompanying steady state temperatures. Each plate was equipped with four thermocouple sensors to detect the bulk temperature of the cold and hot fluids at the intake and output. The performance was evaluated using both parallel and counterflow configurations. Experimental observations are utilized to estimate the temperature difference (∆T) between the inlet and output streams, the logarithmic mean temperature difference (LMTD), and the exergy (E). The measured ∆T and E values for corrugation angles (30°, 45°, and 60°) of CPHE were compared to those of flat plate heat exchangers. For corrugation angles of 30°, 45°, and 60°, the values of ∆T and E (efficiency) increase as the mass flow rate of the fluid increases. An increase in the corrugation angle leads to an increase in turbulence in the flow, which in turn enhances heat transmission. In addition, the thermal effectiveness (ε) was calculated using the NTU method and compared for all of the plates. Key Words: Corrugated plate heat exchanger, Thermal performance, Chevron angle, heat transfer coefficient.

Effect of gadolinium particle size on the performance of a magnetic refrigeration system

This study investigates the influence of gadolinium particle size on Magnetic Refrigeration (MR) system performance. Understanding how particle size of Magnetocaloric Materials (MCMs) within a fixed Active Magnetic Regenerator (AMR) volume affects cooling capacity and Coefficient of Performance (COP) is crucial for MR system design. However, research on this influence, especially using an experimental approach, has been surprisingly rare. This is despite the importance of considering various factors like total MCM mass, porosity, and pressure drop. The particles were categorized into five cases based on their sizes, which ranged from 0.50 to 2.00 mm opening sizes of the meshes. The magnetic field source produced the maximum 0.815 and 0.069 T for magnetization and demagnetization, respectively. A total four of AMRs were installed in the MR system for each case study. First, the porosity of the AMRs mostly increased as finer particles were filled up. This led to a tendency of lower mass of the MCMs in the same volume of the AMRs with smaller particles. Second, the temperature span showed the most outstanding value of 11.1 K in the 0.20 utilization factor using the finest particles (0.50–0.85 mm) in a no-load test. It also achieved a wider 8.3 K temperature span under 3.8 W of thermal load, outperforming the other sizes despite the least total mass of the MCMs. The major contribution to these results was the larger heat transfer area between the MCMs and heat transfer fluid inside the AMRs with the smaller particles. Nevertheless, the case with the second-finest particles (0.80–1.18 mm) exhibited the highest COP of 2.6, due to their favorable combination of moderately significant cooling capacity, reasonably small particle size, and elevated porosity that reduced pumping power demand and magnetic force.

A Study on the Production System of Chevron Plate for High Temperature and High Pressure with High Heat Transfer Area

A Study on the Production System of Chevron Plate for High Temperature and High Pressure with High Heat Transfer Area