Transfer Devices Research Articles

Heat transfer and pressure drop characteristics of the silicone-based plate heat exchanger

The paper presents an experimental investigation of a silicone based heat exchanger, with passive heat transfer intensification by means of surface enhancement. The main objective of this paper was to experimentally investigate the performance of a heat exchanger module with the enhanced surface. Heat transfer in the test section has been examined and described with precise measurements of thermal and flow conditions. Reported tests were conducted under steady-state conditions for single-phase liquid cooling. Proposed surface modification increases heat flux by over 60%. Gathered data presented, along with analytical solutions and numerical simulation allow the rational design of heat transfer devices.

Accelerating flow for engine oil base fluid with graphene oxide and molybdenum disulfide nanoparticles: modified fractional simulations

Thermal assessment of hybrid nanofluid presents novel applications in enhancing heat transfer devices, solar energy production, extrusion systems, chemical processes, nuclear reactors, cooling processes, etc. Owing to such conveying applications of hybrid nanomaterials, the aim of current research is to justify the impressive thermal mechanism engine oil with the utilization of hybrid nanoparticles. The molybdenum disulfide and graphene oxide nanoparticles are used to reflect the improvement in engine oil thermal performances. The motivations for considering such hybrid nanofluid model are to improve the thermal aspect of engine oil which play a key contribution in the vehicle systems and automobile industry. The problem is further improved with mixed convection and Newtonian heating applications. The oscillating surface is used to endorse the flow. The fractional simulations with the implementation of Caputo–Fabrizio (CF) technique are performed. In contrast to traditional attempts, the modern -Laplace transform is used to compute the integration task.

Characterization of education, technical practices and attitudes of Portuguese pharmacy technicians towards manipulation of cytotoxic drugs.

Pharmacy professionals that manipulate cytotoxic drugs need to undergo educational programs, adopt the most convenient practices, and use appropriate equipment to avoid, as far as possible, occupational exposure to cytotoxic drugs. The main goal of this work is to characterize the education, technical practices, and attitudes towards cytotoxic drugs, of Portuguese pharmacy technicians. A questionnaire comprising eleven questions deemed pertinent was elaborated and subsequently validated by a pilot test. The anonymous, web-based survey was conducted between December 2022 and January 2023, by graduated pharmacy technicians that had manipulated cytotoxic drugs between 2017 and 2022. A total of 77 pharmacy technicians responded to the survey. Although sixty-six pharmacy technicians (86%) had been trained before beginning to manipulate cytotoxic drugs, the promotion of regular post-admission training by the institutions is sparse - only assumed by 53% of the pharmacy technicians (n = 41). All participants reported using gloves and gown during manipulation and the use of double gloves was common (99%; n = 76). Compliances with the recommended limit time for uninterrupted manipulation activity (82%; n = 63) and systematic double-checking (86%; n = 66) were high, but the regular use of sterile gauze around syringe connection sites 58% (n = 45), was less frequent. None of the surveyed pharmacy technicians used closed-system transfer devices (CSTD) and 41 (53%) of those who used spikes did not thoughtfully use these devices. The implementation of regular training programs in manipulating cytotoxic drugs should be fostered, to promote the more judicious use of engineering controls and transversal adoption of the safest technical practices.

Experimental and Theoretical Study on Operation Characteristics of an Oscillating Heat Pipe

An oscillating heat pipe (OHP) is an effective heat transfer device for the thermal management of electronic devices. However, the heat transfer mechanism of the OHP was not fully understood due to its complicated operation characteristics. In this paper, the thermal performance of an OHP was experimentally studied. The condensation and evaporation temperature variations were monitored under different heat inputs and were then used to evaluate the OHP system operating characteristics. Thermal resistance was used as a key parameter to evaluate the thermal performance of the OHP system. The results indicated that as the heat input increased from 25 to 100 W, the average thermal resistance decreased while the stable evaporating and condensing temperatures increased. The equivalent heat transfer coefficient was derived theoretically. It showed that the reciprocal of the radial heat transfer coefficient increased with increasing liquid film thickness. Based on this result, an empirical correlation was proposed to evaluate the thermal resistance of an OHP system. This correlation was validated using both the experimental data provided in this study and the data collected from the open literature. The comparison results indicated that the proposed empirical correlation could reasonably predict the thermal resistance under different filling ratios and heat inputs.

Effect of Flow Resistance of Floating-Type Check Valves on Heat Transfer Characteristics of an Oscillating Heat Pipe

Abstract An oscillating heat pipe with check valves (CVOHP) is an attractive heat transfer device for future spacecraft with considerable heat dissipation and ground applications. This study aims to clarify the effect of the flow resistance of floating-type check valves on the heat transfer characteristics of the CVOHP using a one-dimensional slug flow model, which simulates the five-turn CVOHP used in the on-orbit experiment by the authors. The numerical simulations were conducted for different flow resistances, positions, and numbers of check valves. The results showed that the thermal resistance of the CVOHP increases with the flow resistance of the check valves, while there is no significant effect on the startup characteristics. The thermal resistance increased by more than 100% in the worst case, and the recommended flow resistance coefficient of the check valve was below 100 in this study for high thermal performance. The thermal resistance increases with an increasing number of high-resistance check valves but is less affected by the position of the valve. Additionally, the higher the heat input, the greater the effect of the flow resistance of the check valves. According to the findings in this study, it is necessary to control the flow resistance of the floating-type check valves at a low level for the high thermal performance of a CVOHP.

Redesign of a Failed Hoisting Shaft of a Vertical Transfer Device

The redesign of a failed hoisting shaft belonging to a 10 m stroke vertical transfer device (VTD) is presented. Firstly, the operation of the VTD is thoroughly analysed, the variation of loads and moments along the operating cycle is characterised, and transients such as emergency stop loads are calculated. The selection of safety factors and duty cycle factors was followed by the shaft sizing. After an initial rough sizing, the high-cycle fatigue (HCF) design for cyclic bending moments was performed, first considering constant torque and then considering cyclic torque. The number of bending and torsion cycles performed by the hoisting shaft over 10 years was shown to exceed 106, and an infinite life design is mandatory. The analyses showed that the initial shaft diameter was insufficient, thus justifying the failures observed before the present redesign. A classical fatigue model combining torsional shear stresses with bending stresses was used to take into account reversed torsional loading and ensure infinite fatigue life. This work highlights the need to thoroughly understand a machine’s operating cycle so that the wrong premises for fatigue design calculations are not assumed.

Biomimetic Copper Forest Structural Modification Enhances the Capillary Flow Characteristics of the Copper Mesh Wick

In a two-phase heat transfer device, achieving a high capillarity of the wick while reducing flow resistance within a limited space becomes the key to improving the heat dissipation performance. As a commonly used wick structure, mesh is widely employed because of its high permeability. However, achieving the desired capillary performance often requires multiple layers to be superimposed to ensure an adequate capillary, resulting in an increased thickness of the wick. In this study, an ultra-thin biomimetic copper forest structural modification of copper mesh was performed using an electrochemical deposition to solve the contradiction between the permeability and the capillary. The experiments were conducted on a copper mesh to investigate the effects of various conditions on their morphology and capillary performance. The results indicate that the capillary performance of the modified copper mesh improves with a longer deposition time. The capillary pressure drops can reach up to 1400 Pa when using ethanol as the working fluid. Furthermore, the modified copper mesh demonstrates a capillary performance value (ΔPc·K) of 8.44 × 10−8 N, which is 1.7 times higher than that of the unmodified samples. Notably, this enhanced performance is achieved with a thickness of only 142 μm. The capillary limit can reach up to 45 W when the modified copper mesh is only 180 μm. Microscopic flow analysis reveals that the copper forest modified structure maintains the original high permeability of the copper mesh while providing a greater capillary force, thereby enhancing the overall flow characteristics.

Critical Point Drying of Graphene Field-Effect Transistors Improves Their Electric Transport Characteristics.

A critical point drying (CPD) technique is reported with supercritical CO2 as a cleaning step for graphene field-effect transistors (GFETs) microfabricated on oxidized Si wafers, which results in an increase of the field-effect mobility and a decrease of the impurity doping. It is shown that the polymeric residues remaining on graphene after the transfer process and device microfabrication are significantly reduced after the CPD treatment. Moreover, the CPD effectively removes ambient adsorbates such as water therewith reducing the undesirable p-type doping of the GFETs. It is proposed that CPD of electronic, optoelectronic, and photonic devices based on 2D materials as a promising technique to recover their intrinsic properties after the microfabrication in a cleanroom and after storage at ambient conditions.

Polymeric Materials Selection for Flexible Pulsating Heat Pipe Manufacturing Using a Comparative Hybrid MCDM Approach.

The right choice of polymeric materials plays a vital role in the successful design and manufacture of flexible fluidic systems, as well as heat transfer devices such as pulsating heat pipes. The decision to choose an acceptable polymeric material entails a variety of evaluation criteria because there are numerous competing materials available today, each with its own properties, applications, benefits, and drawbacks. In this study, a comparative hybrid multi-criteria decision-making (MCDM) model is proposed for evaluating suitable polymeric materials for the fabrication of flexible pulsating heat pipes. The decision model consists of fourteen evaluation criteria and twelve alternative materials. For this purpose, three different hybrid MCDM methods were applied to solve the material selection problems (i.e., AHP-GRA, AHP-CoCoSo, and AHP-VIKOR). According to the results obtained, PTFE, PE, and PP showed promising properties. In addition, Spearman's rank correlation analysis was performed, and the hybrid methods used produced consistent rankings with each other. By applying MCDM methods, it was concluded that PTFE is the most suitable material to be preferred for manufacturing flexible pulsating heat pipes. In addition to this result, PE and PP are among the best alternatives that can be recommended after PTFE. The study supports the use of MCDM techniques to rank material choices and enhance the selection procedure. The research will greatly assist industrial managers and academics involved in the selection process of polymeric materials.

Thermal and phase change process analysis in a porous vented circular cavity under the impacts of inner rotating surface and inclined magnetic field during nanoliquid convection

In this study, thermal and phase change process in a circular porous vented cavity (P-VC) are numerically analyzed with finite element method considering magnetic field and inner surface rotation during nanofluid convection. The control of convective heat transfer and thermal management in porous cavities are crucial in applications for electronic cooling, heat exchangers, convective drying, and many other heat transfer devices. The numerical analysis is carried out for various values of the relevant parameters (Reynolds number—Re, rotational Reynolds number—Rew, Hartmann number—Ha, opening ratio—Ri) as follows: 500≤Re≤2000, −5000≤Rew≤5000, 0≤Ha≤80, 1≤Ri≤3. The phase change process often accelerates with higher Re when rotations are active. The rotations cause the full phase transition time (TR) to decrease by roughly 15% at the highest Re. The phase change process speeds up when both CW and CCW rotations are used at their highest values. The impacts of Ha on the TR variation is found as 33%. The thermal performances are slightly influenced by the variation of inner surface rotations and magnetic field strength. However, highest impact on thermal process and phase change is obtained when varying the inlet port size. The TR variation becomes 57% while heat transfer enhancement factor is obtained as 3.5. The optimal parameter combination to provide the highest thermal performance is (Ha, Rew, Ri) = (30.85, −4145, 2.98).

Investigation into the operation of an autothermal two-section subbituminous coal fluidized bed gasifier

Using a newly developed experimental setup, the features and advantages of an autothermal single-casing atmospheric subbituminous coal fluidized bed air-blown gasifier, combining a combustion and gasification section, and mixing the dispersed phase (inert material, char) and heat exchange between them through an annular transfer device, have been revealed. To increase the efficiency of the gasifier, an experimental-computational method was developed find the conditions for optimal operation, combining changing the annular flow’s geometry and regulating the primary air for gasification. A simple and reliable multizone thermodynamic calculation model makes it possible to predict the composition of char and syngas in the gasification section with acceptable accuracy. This method confirmed that a two-section fluidized bed gasifier can provide efficient gasification of solid fuels and is suitable for use in small-scale cogeneration plants. Syngas with a heating value of 3.6–4.5 MJ/m3 and CGE of 38.2%–42.3% was obtained in the experimental setup without optimizing the primary air flow rate. With optimization, the indicators increased to the heating value of syngas of 5.20–5.34 MJ/m3 and CGE of 42.5%–50.0%. With heat regeneration of 0.8, CGE increases to 70%.

Entropy optimized flow of Sutterby nanomaterial subject to porous medium: Buongiorno nanofluid model

Owing to enhanced thermal impact of nanomaterials, different applications are suggested in engineering and industrial systems like heat transfer devices, energy generation, extrusion processes, engine cooling, thermal systems, heat exchanger, chemical processes, manufacturing systems, hybrid-powered plants etc. The current communication concerns the optimized flow of Sutterby nanofluid due to stretched surface in view of different thermal sources. The investigation is supported with the applications of external heat source, magnetic force and radiative phenomenon. The irreversibility investigation is deliberated with implementation of thermodynamics second law. The thermophoresis and random movement characteristics are also studied. Additionally, first order binary reaction is also examined. The nonlinear system of the governing problem is obtained which are numerically computed by s method. The physical aspects of prominent flow parameters are attributed graphically. Further, the analysis for entropy generation and Bejan number is focused. It is observed that the velocity profile increases due to Reynolds number and Deborah number. Larger Schmidt number reduces the concentration distribution. Further, the entropy generation is improved against Reynolds number and Brinkman parameter.

Selective laser melting of 316L–CuCrZr bimetallic structure via IN718 transition layer

Steel/copper bimetallic structural materials combine the good strength and corrosion resistance of steel with the high thermal and wear resistance of copper and have been widely used in fusion reactors, conformal cooling channels, and heat transfer devices. Due to the large difference in thermal and physical properties of steel and copper, and the immiscibility of steel and copper, the bonding interface usually produces a large residual stress during the forming process, which leads to the formation of interface cracks. In order to combine CuCrZr with 316L stainless steel by using selective laser melting technology, IN718 was deposited on 316L stainless steel as a transition layer. The effects of the IN718 alloy transition layer on the microstructure, phase composition, and mechanical properties of the interface of 316L–CuCrZr were studied. IN718–316L had no defects such as pores and cracks at the interface and achieved good metallurgical bonding. The IN718–CuCrZr interface area and copper side had round key holes and relatively small pores. In the solidification process, IN718 preferentially solidified in the shape of fine particles, providing a nucleation point for the copper grain, thus forming equiaxed grains because of the high cooling rate of the interface. No macroscopic defects were observed at the bonding position of the 316L–IN718–CuCrZr samples, and the elements at the interface were fully diffused by each other. The tensile strength of the 316L–IN718–CuCrZr samples reached 403 MPa, and the interface strength was significantly improved upon the addition of the transition layer.

Design and optimization of novel transceiver device for one-way single-wire power transfer

Design and optimization of novel transceiver device for one-way single-wire power transfer

Urine transfer devices may impact urinary particle results: a pre-analytical study.

Well-standardized procedures in the pre-analytical phase of urine diagnostics is of utmost importance to obtain reliable results. We investigated the effect of different urine collection methods and the associated urine transfer tubes on urine test strip and particle results. In total, 146 selected urine samples were subdivided into three different collection containers and subsequently transferred into its accompanying transfer tube (BD, Greiner, Sarstedt vacuum and Sarstedt aspiration). As reference, the original urine sample was directly measured on the analyser. Both chemical test strip analysis (Sysmex UC-3500) and fluorescence flow cytometry particle analysis (Sysmex UF-5000) were performed on all samples. No statistically significant differences in test strip results were found between the studied transfer methods. On the contrary, transfer of urine samples to the secondary tubes affected their particle counts. Clinically significant reductions in counts of renal tubular epithelial cells and hyaline casts were observed using the BD and Greiner transfer tubes and in counts of pathological casts using the BD, Greiner and Sarstedt vacuum tubes. The results of this study indicate that the use of urine transfer tubes may impact counts of fragile urine particles. Clinical laboratories need to be aware about the variation that urine collection methods can induce on urine particle counts.

Heat generation and transfer simulation of a high temperature heat pipe under induction heating based on a coupled model

High temperature heat pipes are highly efficient heat transfer devices, and induction heating is often utilized in their performance tests. However, issues exist in evaluating the equivalence between induction heating and surface heating encountered in typical application scenarios, and in quantifying the accurate input heat flux of induction heating. In order to identify the key influencing factors and investigate their effects on heat generation and transfer within high temperature heat pipes under induction heating, a finite element thermal-electrical coupled model is developed based on the pseudo wick thermal conductivity model and electromagnetic theory. The effects of frequency (10 kHz, 100 kHz, 300 kHz), loaded current (10 ∼ 890A), cooling coefficient (10 ∼ 250Wm-2K−1) and temperature (300 ∼ 1000 K) are investigated. Over 98% of the induction heat is found to be generated in the evaporator section, with a considerable proportion generated in the annular channel (38 ∼ 52%) and the capillary wick (23 ∼ 26%) at low frequency (10 kHz). The wall temperature of the evaporator section is slightly lower than the temperature of the annular flow channel or even the capillary wick at weak cooling boundary conditions (<130Wm-2K−1@10 kHz, <50Wm-2K−1@100 kHz, <30Wm-2K−1@300 kHz). Quantitative calibration formulas of induction heat are established in relation to frequency, current, and temperature via two sets of quadratic polynomial fitting. The results can be used as reference for design and evaluation of transient and steady-state tests of heat pipes under induction heating.

Capillary limit of a sodium screen-wick heat pipe

High-temperature alkali-metal heat pipes are passive heat transfer devices, where the capillary pressure created by the menisci in the wick pumps the condensed fluid back to the evaporator. Thus, the heat pipe heat transfer capacity is limited by the maximum capillary pressure at high heat fluxes. This work presents a two-dimensional heat and mass transfer model for alkali metal heat pipes. In addition to the traditional wall heat conduction model, the model also incorporates gas–liquid flow heat transfer and capillary structure models, enabling the model to simulate both steady-state operation and transient capillary limit processes. The predictions of the model agreed well with experimental data. The predicted critical heat flux temperature has an error of less than 20℃ and a relative error of 6%. The predicted transient sequences are consistent with the measurements. The model shows that capillary limit is affected by inclination angle, heat flux, and wick structure. For inclinations, the critical heat flux at the capillary limit is linearly related to the inclination angle with the predicted temperature rising 2–10℃/s during the early stage of the capillary limit critical heat flux condition. The evaporator temperature oscillates before the capillary limit with positive inclinations. For heat fluxes, increasing the heat flux by 17% increases the temperature increase rate 10 fold with a longer dryout length. The evaporator exhibits hysteresis after the capillary limit due to partial dryout of evaporator. For wick structures, reducing the mesh screen pitch from 80 μm to 15 μm reduces the critical heat flux to 10% of the CHF at 80 μm. This model can accurately predict the heat pipe temperature variations at the capillary limit and can explain the physical mechanisms for the dryout oscillations and recovery hysteresis at the capillary limit. Thus, the measurements and model provide analytical guidelines for designing heat pipe cooling systems.

GSM Based Fall Alert Monitoring System Using Keypad Device

The International Classification of Diseases 11 (2018), published by the World Health Organization, divides vision impairment into two categories: distance and near-presenting vision impairment. The system prototype is necessary. It is a control order from the operator. It is the main form of communication for mute, visually impaired, and hearing persons. The goal of this initiative is to improve the quality of life for people with disabilities. By making things more accessible, it will be easier to meet their requirements and offer them challenges that will keep them motivated. The improvement of speech, hearing, and vision impairments is the main goal of this initiative. Here, organizing and categorizing the portable key- board device for information transfer from one location to another is the major objective.

Thermal performance and flow analysis in a brazed plate heat exchanger using MWCNT@water/EG nanofluid

In recent years, the growth of energy consumption and the need to optimize it have drawn the attention of researchers to technologies that can increase the performance of heat transfer devices such as plate heat exchangers. One of these solutions is the use of nanoparticles in common fluids. Despite the many advantages of MWCNT, not enough attention has been paid to its application in plate heat exchangers. The purpose of this study is to investigate the thermal performance and flow of a brazed plate heat exchanger using MWCNT nanoparticles in the cooling fluid of water/Ethylene glycol. The results of the UV spectrum showed that the concentration of 0.05 wt% nanofluid has the most stability. Therefore, the tests required for the two factors of the volume flow rate of cold fluid and temperature of hot fluid were performed at three levels using the response surface method. The results show that at 55 ̊C temperature of hot fluid and volume flow rate of 23.4 l/min of cold fluid, the convection heat transfer coefficient and the heat transfer rate are increased by 20.97% and 34.3% compared with the base fluid. Also, The Nusselt number, pressure drop, friction factor, and pumping power increased by enhancement of the hot fluid temperature and volume flow rate of cold fluid. These parameters of nanofluid at 23.4 l/min and 55 ̊C compared to base fluid increased by 94.45%, 11.25%, 12.87%, and 11.36%, respectively. This study shows better performance at high temperatures compared to similar studies.

Utilizing fly ash from a power plant company for CO2 capture in a microchannel

The separation of carbon dioxide by mineral waste with alkaline properties is an innovative technology for storing carbon dioxide. This experiment utilized an aqueous solution containing seawater and fly ash in a microchannel to investigate CO2 absorption. In all experiments, the concentration of CO2 in feed gas was 10.5% at atmospheric pressure. A number of variables were examined, including temperature (10–50 °C), inlet solvent flow rate (50–300 ml/h), inlet gas flow rate (50–250 ml/min), as well as fly ash to seawater ratios (1:25, 1:50, 1:75, 1:100, 1:125,1:150, 1:175 and 1:200 gr/ml). The study found that an increase in the concentration of fly ash in the solution and a higher flow rate of the solvent led to a noteworthy improvement in both the absorption percentage and volume transfer coefficient of gas-based gas. The increase in gas flow rate led to a decrease in the percentage of CO2 removal and an increase in the gas-based volumetric mass transfer coefficient. Under optimal operating conditions, absorption percentages were 96.25% and gas-based volumetric mass transfer coefficients were 63.21 (kmol h −1m−3 kPa−1) were achieved even though the temperature in the range of (10–50 °C) has a negative impact on the absorption rate. According to the overall gas-based volumetric mass transfer coefficient, microchannel reactors provide higher absorption efficiency than other mass transfer devices.