Direct Heating Research Articles

Highly Anisotropic Thermally Conductive Dielectric Polymer/Boron Nitride Nanotube Composites for Directional Heat Dissipation.

An ideal dielectric material for microelectronic devices requires a combination of high anisotropic thermal conductivity and low dielectric constant (ɛ') and loss (tan δ). Polymer composites of boron nitride nanotubes (BNNTs), which offer excellent thermal and dielectric properties, show promise for developing these dielectric polymer composites. Herein, a simple method for fabricating polymer/BNNT composites with high directional thermal conductivity and excellent dielectric properties is presented. The nanocomposites with directionally aligned BNNTs are fabricated through melt-compounding and in situ fibrillation, followed by sintering the fibrous nanocomposites. The fabricated nanocomposites show a significant enhancement in thermal properties, with an in-plane thermal conductivity (K‖) of 1.8 Wm-1K-1-a 450% increase-yielding a high anisotropy ratio (K‖/K⊥) of 36, a 1700% improvement over isotropic samples containing only 7.2 vol% BNNT. These samples exhibit a 120% faster in-plane heat dissipation compared to the through-plane within 2 s. Additionally, they display low ɛ'of ≈3.2 and extremely low tan δ of ≈0.014 at 1kHz. These results indicate that this method provides a new avenue for designing and creating polymer composites with enhanced directional heat dissipation properties along with high K‖, suitable for thermal management applications in electronic packaging, thermal interface materials, and passive cooling systems.

Platinum-Ruthenium Bimetallic Nanoparticle Catalysts Synthesized Via Direct Joule Heating for Methanol Fuel Cells.

Platinum-Ruthenium (PtRu) bimetallic nanoparticles are promising catalysts for methanol oxidation reaction (MOR) required by direct methanol fuel cells. However, existing catalyst synthesis methods have difficulty controlling their composition and structures. Here, a direct Joule heating method to yield highly active and stable PtRu catalysts for MOR is shown. The optimized Joule heating condition at 1000°C over 50 microseconds produces uniform PtRu nanoparticles (6.32wt.% Pt and 2.97 wt% Ru) with an average size of 2.0 ± 0.5 nanometers supported on carbon black substrates. They have a large electrochemically active surface area (ECSA) of 239 m2 g-1 and a high ECSA normalized specific activity of 0.295mA cm-2. They demonstrate a peak mass activity of 705.9mA mgPt -1 for MOR, 2.8 times that of commercial 20 wt.% platinum/carbon catalysts, and much superior to PtRu catalysts obtained by standard hydrothermal synthesis. Theoretical calculation results indicate that the superior catalytic activity can be attributed to modified Pt sites in PtRu nanoparticles, enabling strong methanol adsorption and weak carbon monoxide binding. Further, the PtRu catalyst demonstrates excellent stability in two-electrode methanol fuel cell tests with 85.3% current density retention and minimum Pt surface oxidation after 24 h.

6E analysis and particle swarm optimization of a novel ultra-high temperature solar cogeneration system fusing thermochemical energy storage and multistage direct heat transfer

The reshaping of the energy development model depends on the penetration of renewable energy on the input side and the substitution of electrical energy on the supply side. Therefore, this research proposes a novel solar cogeneration system in which the Brayton cycle possesses triple pressure and can be flexibly coupled directly to each subsystem under supercriticality without intermediate exchangers. Firstly, a series of research tasks are executed sequentially, including model establishment, cycle potential comparison, operating parameter analysis, and multi-objective particle swarm optimization. Secondly, the exergy flow rate, consumption rate, and 6E (energy, exergy, exergoeconomic, exergoenvironmental, emergoeconomic, and emergoenvironmental) performances of each subsystem and subcomponent are thoroughly discussed. Lastly, the operating performance, economic benefits, and regional characteristics of each subsystem and the cogeneration system are explored. After optimization, the exergy efficiency, average advanced exergy-emergy factor, and advanced exergy-emergy impact difference of the system are 22.72 %, 56.17 %, and 23.97 %. Compared with similar research, the energy efficiency of the system is improved by 8.2 %, which can repay the capital cost in 8.83 years, and the economic benefit reaches $5,503,086 for the entire service year. The system embodies excellent 6E performance, aligns with the goals of reshaping the energy development model, and provides guidelines for the development of ultra-high temperature solar cogeneration.

Optimization of iron nanoparticle sizethrough green synthesis using leaf extract from selective members of citrus family

Nanoparticles (NPs) are known for their unique attributes due to their small size that lies in atomic domain. The unique properties of NPs have prompted researchers to explore ways to make these materials with controlled size and morphology. The green synthesis of NPs is the most promising way of preparing NPs due to its convenience, environmentally friendly nature and cost effectiveness. This research work was mainly concerned with the green synthesis of iron nanoparticles (INPs) using three members of the citrus family (i.e., grapefruit, lemon, orange) under direct heating and ultrasound mediated conditions. The prepared NPs were investigated by different characterization techniques including Particle Size Analyzer (PSA), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The results revealed and demonstrated that the NPs thus formed differed not only in their sizes but also in the number of phases in PSA. The NPs prepared from extract of grapefruit leaves showed uniformity when lower concentration of extract was used; however, when higher volume were used formation of two phases was observed. In the case of ultrasound mediated synthesis, the formation of two phases was observed even at lower volume of grapefruit leave extract. In the case of nanoparticles (NPs) prepared using lemon leaf extract, both heating and ultrasound-mediated conditions resulted in the formation of multiple phases. Conversely, for NPs prepared with orange leaf extract, ultrasound-mediated conditions consistently led to the formation of a single phase, regardless of the volume of plant extract used. However, the size of these phases varied, showing an irregular trend with the volume of the plant extract. The FTIR spectra, DLS results, and SEM images reflected quite drastic differences in NPs before and after calcination. All synthesized NPs exhibited the same surface plasmon resonance of 700 nm.

Recent advancements in solar collector-evaporator for direct expansion solar heat pump

The direct expansion solar heat pump (DX-SHP) is a competent and sustainable option for domestic heating and drying applications. The solar collector-evaporator is a vital component of DX-SHP, which operates on solar energy and low-temperature ambient energy. The heat collection capacity, coefficient of performance, and evaporation temperature are used to quantify its performance. In this context, a systematic literature review on recent advancements in the collector-evaporator of DX-SHP is presented. This paper highlights and discusses the various configurations of solar collector-evaporators, theoretical and experimental investigations, and the selection method of eco-friendly refrigerants. The impact of different performance factors, such as ambient conditions, structural parameters, and types of refrigerants, on solar collector-evaporators is also reviewed. The optimal range for solar radiation, wind speed, and temperature is found to be 350 W/m2-700 W/m2, 0.5 m/s -2.5m/s, and 5°C to 35°C. The DX-SHP system produces hot water from 15°C to 60°C, with an average COP of 1.5 to 4.5. The finned solar collector-evaporator with R290 refrigerant performs optimally in various climatic conditions. Integrating solar collector-evaporators with innovative technologies such as microchannel, heat pipe, thermoelectric generators, photovoltaic thermal collectors with compound parabolic and Fresnel lenses can improve the system's performance. In this review, researchers can find scope for performance enhancement of the collector-evaporator used in DX-SHP.

Effect of induced electric field parameters on physiochemical characteristics and microorganism of orange juice

AbstractThe induced electric field (IEF) was produced via an oscillating magnetic field, for direct heating of orange juice within a winding coil. During the process, the applied magnetic field was at the range from 0.07 to 1.43 T with 50 kHz. Then, the numerical relationships between excitation voltage, magnetic field, IEF, induced current density, magnetomotive force and energy efficiency were investigated. Since a rectangular wave of excitation voltage was applied, the sawtooth waveform of induced voltage or IEF loaded on the juice was observed. As the magnetic field increased, outlet temperature and induced current density in the juice was improved, the maximum values were 99.5°C and 0.50 A/cm2, respectively, at a conductivity 4.53 mS/cm for the residence time of 4.5 min. However, the efficiency of the process exhibited a negative correlation with the escalation of excitation voltage. At initial colony count about 4.50 log colony‐forming units/mL, the IEF pasteurization reduced all the aerobic microorganisms, molds, and yeasts in the juice, which were evaluated at detectable limits below 1 log colony‐forming units/mL. Moreover, all treatments had no significant effects on pH, total soluble solids and titratable acidity of the juice (p > 0.05). In particular, there was also no significant change in color parameters after IEF pasteurization (p > 0.05). It indicated a significant decrease in vitamin C and total phenolic content of the control groups (p > 0.05), but no significant change in carotenoid content was observed in all treated juice (p > 0.05). heating technology using IEF has the potential to the pasteurization of fruit juice.Practical applicationsInduction electric field technology has progressed rapidly in the past 2 years, it can use oscillating alternating magnetic field to realize the direct heating of liquid food. The process has thermal and non‐thermal effects, at 65–70°C, within 15–30 s to achieve the commercial asepsis of acidic liquid food. After the pasteurization, it can better maintain the color and flavor of the juice. We have assembled a laboratory prototype for testing in the early stage, the processing capacity is at the range of 0–10 L/h. Currently, the system has been able to reach the pilot production scale with the processing capacity of 100–500 L/h. Through the use of highly permeable magnetic materials, the energy consumption per ton of juice processing is controlled at 120 k·Wh level for the pasteurization and is expected to achieve a larger processing capacity in the future.

Optimising design and operation of sewage source heat pump: techno-economic and environmental assessment

ABSTRACT Heat pump can be used to recover abundant thermal energy contained in the discharge of municipal wastewater treatment plants. While there are some design standards for common heat pump systems, the design of a sewage source heat pump (SSHP) system is still often based on a fixed heat load and neglects the interdependencies between the equipment sizing and operating parameters. To address the issue that previous design methods have not balanced investment and operational costs well from a global optimisation perspective, this work formulates the simultaneous optimisation of SSHP design and operation as a non-linear programming problem. The proposed model features the consideration of multiple working conditions caused by the impact of ambient temperature variation on the heat load of the SSHP system. The feasibility and potential benefits of the optimised SSHP system are also evaluated by incorporating techno-economic performances and environmental impact analyses into the mathematical framework. A case study is carried out to demonstrate the effectiveness of the proposed methodology. The results show that the total annual cost of the optimally designed and operated SSHP in Harbin could be 9% lower than in Beijing and 39% lower than in Shanghai, suggesting that constructing and running the SSHP system in severe cold regions with great heating demands might be more economical than in less cold regions. The CO2, SO2, and NOx emissions of the SSHP could be approximately 50% less than that of coal-fired boiler heating, and 80% less than that of direct electric heating with coal-fired electricity.

Insight into phase stability and thermoelectric properties of semiconducting iron silicides with manganese substitution: β-Fe1−xMnxSi2 (0≤x≤0.05)

Metal-doped iron silicides (β-FeSi2) are promising thermoelectric materials for high-temperature applications. However, the addition of metal dopants usually causes the formation of secondary metallic phases, resulting in the degradation of thermopower. Here we report the stability of semiconducting β-phase (higher than 95 %) of Mn-doped β-FeSi2 obtained at Mn concentration from 1 % to 5 %, where the samples were prepared through direct arc melting and heat treatment process. The carrier density remarkably increases with Mn content, but the mobility decreases. The electrical resistivity significantly decreases with Mn content. The Seebeck coefficient of Mn-doped samples is improved and stable at high-temperature regions because of the reduction of the bipolar effect and β-phase stability. The thermal conductivity slightly increases with Mn. As a result, the maximum thermoelectric power factor PF = 970 μWm−1K−2 and dimensionless figure of merit ZT = 0.12 at 800 K are obtained in a 3 % Mn-doped sample. The stability of β-phase and the improved carrier density are the origins of enhanced thermoelectric properties, where the Seebeck coefficient is improved, and the electrical resistivity is reduced. Our study provides insight into the importance of phase stability for enhancing thermoelectric transport in Mn-doped β-FeSi2.

Effects of Direct Aging Heat Treatments on the Superelasticity of Nitinol Produced via Laser Powder Bed Fusion

This work investigates the effects of short-time direct aging heat treatments on the mechanical properties and microstructure of additively manufactured Nitinol (NiTi) alloy. Cylindrical samples were produced through laser powder bed fusion (L-PBF), directly aged at different temperatures and compared to the solution annealed and aged conditions. Compression tests were carried out at room temperature both in cyclic mode at constant strain and incremental cyclic mode, to provide a comprehensive analysis on the superelastic features of NiTi after direct aging heat treatments. Furthermore, cyclic compression tests were performed at 37 °C to evaluate the superelastic effect at the body temperature and, therefore, the possibility to use these treatments for biomedical components. The effects of direct aging on the microstructure were characterized using transmission electron microscopy (TEM). High cyclic stability and superelastic recovery up to 10 pct of deformation emerged for the direct aged alloys. The comparable results obtained with and without the solution treatment points out that this step was not necessary in reaching superelasticity, proving the effectiveness of direct aging.

Thermal performances and invisible thermal barrier formation mechanism of arc-shaped metal-fin-enhanced thermally activated building envelopes with directional heat charging feature

Thermal performances and invisible thermal barrier formation mechanism of arc-shaped metal-fin-enhanced thermally activated building envelopes with directional heat charging feature

More Accurate Quantification of Direct Aerosol Radiative Effects Using Vertical Profiles of Single‐Scattering Albedo Derived From Tethered Balloon Observations

AbstractAerosol single‐scattering albedo (SSA) is the most critical factor for the accurately calculating of aerosol radiative effects, however, the observation of vertical profiles of SSA is difficult to realize. Current assessments of aerosol radiative effects remain uncertain because of the lack of long‐term, high‐resolution vertical profiles of SSA observations. High‐resolution SSA vertical profiles were observed in a semi‐arid region of Northwest China during winter using a tethered balloon. The observed SSA vertical profiles were used to calculate the aerosol direct radiative forcing and radiative heating rates. Significant differences in the calculated radiative forcing were found (e.g., a 48.3% relative difference for the heating effect in the atmosphere at 14:00) between the observed SSA profiles and the constant assumption with SSA = 0.90. Diurnal variations in the vertical distribution of SSA decisively influenced direct radiative forcing of aerosols. Furthermore, high‐resolution vertical profiles of absorbing aerosols and meteorological parameters provide robust observational evidence of the heating effect of an elevated absorbing aerosol layer. This study provides a more accurate calculation of aerosol radiative forcing using observed aerosol SSA profiles.

A novel preheating system in pressure reduction stations—natural gas directly flowing inside deep borehole heat exchangers

To prevent hydrates from forming during the pressure reduction process in natural gas pressure reduction stations (i.e., city gate stations, CGS), fuel-intensive preheating methods are normally adopted, leading to high fuel consumption and carbon emissions. In this study, an innovative preheating system for natural gas is proposed, which is called the “Direct Geothermal Heating System” (DGHS). The main idea is to inject high-pressure natural gas into geothermal wells before the throttling valve; thus, natural gas is directly heated by the surrounding strata when it flows through the geothermal well. A proper temperature for natural gas should be ensured, as natural gas goes back to the ground for pressure regulation. The idea is performed based on the preheating configuration using coaxial deep borehole heat exchangers (DBHE). A mathematical model describing the flow and heat transfer processes of DGHS through DBHE is established to study its heat transfer characteristics. Additionally, the environmental and economic benefits of the proposed configuration are also investigated. Through the CGS case in this paper, the findings indicate that, over the fifteen years of preheating with a DBHE depth of 2000 m and inlet flow rate of 4.39 × 107 Nm³/year, the outlet temperature of the throttling valve remains within the range of 17 °C–37 °C, meeting the heating requirement of CGS. Among fifteen preheating cycles, the average peak heating power of the DBHE reaches 105.78 kW. In addition, in the 15th year, the proposed system has a 1/3 cost of a traditional line heater, along with a reduction of 46.43 × 105 kg in CO2 emission. The DGHS for natural gas is easy to establish and operate; once it is promoted on a large scale, it will produce huge economic and environmental benefits.

Smoldering ignition and transition to flaming in wooden mulch beds exposed to firebrands under wind

Spotting ignition by firebrands is a significant fire spread pathway at the wildland-urban interface (WUI), where mulch products are commonly used as landscaping materials. Mulch is typically organic in nature, thus it may be easily ignited into a smoldering mode by firebrands and subsequently transition to flaming, leading to direct flame contact and radiant heat exposure to siding materials of adjacent structures. This work quantified the thresholds of smoldering ignition of four common types of commercially available mulch (black mulch (BM), forest floor (FF), redwood (RW), and fir bark (FB)) exposed to heating by smoldering firebrand piles, and their propensity for smoldering-to-flaming transition under external winds (up to 1.4 m/s). We found that there was a minimum mass of firebrand pile to achieve smoldering ignition of mulch (e.g., ∼0.1 g for FF). Beyond this minimum mass, the required wind speed to trigger smoldering ignition generally decreased as the mass of the firebrand pile increased, agreeing well with theoretical analysis. After smoldering ignition, smoldering-to-flaming transition could be observed when the wind speed exceeded a critical value (e.g., ∼1 m/s for FF), which was not affected by the initial spotting process. To achieve smoldering-to-flaming transition, the glowing mulch had to reach a critical temperature of around 850 °C. Mulch samples with larger particle sizes were more likely to smolder and transition to flaming, due to increased oxygen supply through larger inter-particle pores and channels and better firebrand accumulation due to a more crevice-like geometry on the fuel surface. This work advances the fundamental understanding of the ignition and burning behavior of landscaping mulches, and thus contributes to the prevention of extreme WUI fire events.

Sub-minute carbonization of polymer/carbon nanotube films by microwave induction heating for ultrafast preparation of hard carbon anodes for sodium-ion batteries

Hard carbons (HCs) are excellent anode materials for sodium-ion batteries (SIBs). However, the carbonization and granulation of HC powders involve complex processes and require considerable energy. Here, we developed a facile method for manufacturing HC anodes for SIBs via a novel microwave induction heating (MIH) process for polymer/single-walled carbon nanotube (SWCNT) films. Numerical simulations solving electromagnetic field and heat transfer problems revealed the MIH mechanism; the electric current induced by the applied microwave enables direct Joule heating of the SWCNT networks in the composite film. Consequently, the composite films could be heated to the target temperatures (800–1400 °C) and free-standing HC/SWCNT anodes could be prepared by applying MIH for only 30 s. Comparative analyses confirmed that ultrafast MIH is a reliable technique for producing HC anodes and can replace conventional carbonization processes which require a high-temperature furnace. Moreover, the HC/SWCNT anodes prepared by the ultrafast MIH were successfully applied to the SIB full cells. Finally, the feasibility of MIH for scalable roll-to-roll production of HC anodes was verified through local heating tests using a circular sheet larger than a resonator.

Role of power-to-heat and thermal energy storage in decarbonization of district heating

The sector integration of the heat and electricity sectors promotes the flexibility of the energy system. This, together with the already almost carbon dioxide-free electricity supply in Finland, facilitates the environmental transition to a carbon-neutral heating system. In this study, pathways to decarbonize the district heating system in Åland (an autonomous region of Finland) are explored. Especially, the roles of different power-to-heat technologies, e.g., heat pumps and direct electric heating, and thermal energy storage are investigated in the decarbonization of the district heating system. The focus is on studying the impact of varying prices in electricity markets on the operation of climate-neutral district heating systems. For this, three scenarios were modeled over the five years of 2018–2022 with varying demand and electricity market prices by using the modeling software PLEXOS. The study showed that electricity prices, but also reserve market prices, have a very significant impact on the operation cost and profit of a district heating system. Overall, electrification has the strong potential to reduce emissions cost-effectively in a district heating system, but it also makes the system vulnerable to electricity price volatility. It can be concluded that thermal energy storage and reserve market participation are crucial for protecting against cost increases and reducing investment risk.

DEVELOPMENT OF AN EXFOLIATING DERMOCOSMETIC FORMULATION WITH BABASSU FIBERS TO HELP ON THE TREATMENT OF ANDROGENETIC ALOPECIA

Androgenetic alopecia is a condition characterized by hair loss associated with exposure to androgens, occurring in genetically predisposed individuals. It causes terminal hair to be replaced by vellus hair, miniaturizing the hair shaft and decreasing hair density. The removal of the stratum corneum of skin due to mechanical exfoliation facilitates the penetration of active ingredients into the scalp by stimulating blood circulation, which can help hair growth. Society's consumption patterns are constantly changing, being the search for sustainability and ESG (Environment, Social and Governance) trends a very popular topic. The aim of this study was to develop an exfoliating dermocosmetic formulation with babassu fibers to help on the treatment of androgenetic alopecia, using the part of the babassu coconut that was originally discarded by the industry. An oil-in-water emulsion was developed with the surfactants lauryl glucoside and cocoamidopropyl betaine, and the emulsifiers cetostearyl alcohol and glyceryl monostearate. The formulation was then analyzed for organoleptic parameters (color, smell and appearance), density, pH and centrifugation. The formulation showed instability in the presence of direct sunlight and heat, indicating possible impasses for its commercialization, since storage in the bathroom may trigger instability. In this way, it can be assumed that storing the product in a refrigerator or even at room temperature (<25°C) will maintain its stability. Based on the results, future studies are needed to assess the stability of the scrub, and the optimization of the formulation will make it possible to obtain an innovative product.

Evaluation of Life Cycle CO2 Emissions for the LDR-50 Nuclear District Heating Reactor

The LDR-50 low-temperature nuclear reactor is designed for the Finnish and European district heating markets, as an environmentally sustainable heating option for the 2030s. While the carbon footprint of conventional electricity-producing reactors is known to be small, there have been no comprehensive studies on the emission reduction potential when the technology is applied to the heating sector. This paper aims to fill this knowledge gap by means of life cycle assessment (LCA) analysis. The carbon footprint of the LDR-50 heating plant is evaluated, and compared to conventional heating fuels, direct electric heating, and heat pumps. The results of the analysis show that the life cycle CO2 emissions are low, although there are still significant uncertainties related to the construction phase, due to missing data. In addition to carbon footprint, the analysis is also extended to other adverse environmental impacts. It is concluded that significant reductions in CO2 emissions can be achieved by replacing fossil heating fuels with nuclear energy. The technology is considered a viable option alongside biofuels and heat pumps. The overall environmental impacts are low, and the production does not compete for low-carbon electricity or scarce natural resources.

Changes in Total and Available K Contents in Feldspar and Mica Co-pyrolyzed with Poultry Litter at Different Temperatures

Plant available potassium (K) content is very low in K-bearing mineral ores present in Sri Lanka and that restrict their use in crop production as K fertilizer sources. Heating of minerals can increase their plant available forms of nutrients. The objective of this experiment was to study the effect of direct heating of K-bearing minerals at different temperatures and co-pyrolyis with poultry litter (PL) at different rates on their total and available K contents. Poultry litter was co-pyrolyzed with 0, 1 and 5% (w/w) of feldspar and mica at 350, 500, 650 and 900 ℃. K-bearing minerals were also directly heated at these temperatures. With direct heating the mineral, total K contents of feldspar (6.2%) and mica (4.5%) were significantly (p<0.001) increased by 10% and 18%, respectively at 500 ℃ and then decreased by 33 and 65%, respectively at 900 ℃. Available K contents in feldspar (0.05%) and in mica (0.03%) either decreased significantly (feldspar) or did not change (mica) upon direct heating. Increasing pyrolysis temperature up to 650 ℃ increased both total (4.2 to 6.4%), and available K (3.2 to 6.1%) contents in poultry litter biochar (PLB). Co-pyrolysis of PL with feldspar or mica at 1 or 5% rates did not improve the total or available K contents in PLB at these temperatures. We concluded that heat treatment of locally available feldspar and mica or co-pyrolyzing them with PL are not effective technologies to increase their utilization in agriculture.

Investigation of mixing and heat transfer characteristics of long-hole SK direct contact heat exchanger

In this study, in order to improve the efficiency of direct contact heat exchanger (DCHE), SK static mixers with different perforation index (PI) were applied. Numerical simulation (volume of fluid model) were used to investigate the performance of the static mixer, which shape was designed as long-holes, under fixed aspect and helical ratios. The feasibility and accuracy of numerical simulation results were verified by self-established direct contact heat transfer (DCHT) experimental platform. Under six different PI values (0 %, 10 %, 18 %, 26 %, 32 %, and 38 %), the heat transfer performance of DCHE was evaluated by applying two heat transfer mediums (THERMINOL62 and R141b). The results indicated that the gaseous working medium outlet temperature, turbulence intensity, turbulence kinetic energy, and volumetric heat transfer coefficient (VHTC) of the system showed an increasing trend as PI increased from 0 % to 32 %, then a decreasing trend can be observed from 32 % to 38 %. The maximum turbulence intensity and turbulence kinetic energy of 17.56 % and 0.015 m2/s2 can be found in PI = 32 %, as well as a maximum enhancement ratio of 49 % in VHTC compared to PI = 0 % can be achieved. In addition, only a small pressure drop increase is observed in PI = 32 % compared to PI = 0 %.

Hyperthermia on colorectal cancer: gold nanoshells-mediated photothermal therapy

Colon cancer or colorectal cancer is one of the most common malignant neoplasms in the world, characterized by uncontrolled cell growth on the colon mucosa. Treatment approaches depend primarily on the characteristics of the tumor´s localization, size, metastasis, and the health status of the patient. Nanomedicine shows itself as a novelty strategy to overcome the limitations of the therapies used in the clinic due to the disregard of the mechanisms associated with multidrug resistance because of the nanometric size of the particles utilized. Gold nanoshells are spheric structures of an approximate size of 30 nm, coated with an ultrathin gold layer that can absorb near-infrared light and convert it to thermal energy to produce hyperthermia on in vivo models of cancer tumors. Nanoparticles-assisted hyperthermia consists of control, direct, and specific heating against the tumor cells by nanoparticle irradiation with an external power source capable of increasing temperature to 39°C - 45°C without damaging surrounding healthy tissue. Compared with other nanomaterials, gold nanoshells show high biocompatibility and low cytotoxicity, which is why adjuvant chemotherapy and hyperthermia on gold nanoshells is a novel and promising approach for the treatment of colorectal cancer.