Shorter Start-up Time Research Articles

Polyaniline@N-doped macroporous carbon foam as self-supporting anodes for microbial fuel cells

The inefficient extracellular electron transfer (EET) is detrimental to power generation and waste degradation in microbial fuel cells (MFCs). Herein, we report a self-supporting anode for MFCs prepared by graphitization of steamed bread slices followed by in-situ polymerization to fabricate polyaniline@N-doped macroporous carbon foam (PANI@NMCF). The natural nitrogen-containing wheat flour was fermented and carbonized to form NMCF with a high specific surface area of 818.1 m2 g−1. After the NMCF surface modified by PANI, the enhanced hydrophilicity and conductivity of the PANI@NMCF anode would facilitate microbial adhesion, biofilm formation, and electron transfer. The surface improvements enhance the EET process for high-performance MFCs, including a short startup time of 21.7 h, high maximum output power density of 1160 ± 17 mW m−2, and decolourisation efficiency of 88.6 ± 1.2% for 36 h. The chemical oxygen demand removal efficiency was about 84.6 ± 1.1% at end of the operating cycles. This work provides a good foundation for our future development of carbon-based electrode materials for energy conversion and storage devices.

Influence of electrode surface charge on current production by Geobacter sulfurreducens microbial anodes

Positively charged electrode surfaces are thought to enhance electrostatic interaction with mostly negatively charged bacteria cell surface, thereby improving microbial fuel cell performance. In this work, electrostatic self-assembly of charged polymers was used to systematically modify the surface of indium tin coated electrodes. Evaluation was based on start-up time, maximum current, biofilm thickness and coulombic efficiency of microbial Geobacter sulfurreducens anodes. Coated electrodes were polarized to +0.1 V vs. SHE as biological duplicates. The thickest biofilms and in turn highest current density and shortest start-up time was achieved for negatively charged electrode surfaces like non-coated ITO or polystyrol sulfonate coated electrodes, while positively charged chitosan, negatively charged alginate and positively charged polyethylene imine, in the particular order, produced thinner biofilms, with less current and longer start-up time. This finding contradicted the initial hypothesis. Most experiments on electrode surface modifications are accompanied by an increase in available electrode surface which makes it difficult to extract solely the effect caused by the surface modification. Our study showed the importance of considering also factors other than the surface charge, e.g. potential interactions of the surface modification with the conditioning film and the medium, namely the attraction of cations by a negatively charged surface.

Effects of impeller geometry modification on performance of pump as turbine in the urban water distribution network

Nowadays, by increasing energy consumption, micro-scale energy production has received a lot of attention worldwide. Pressure control and electricity generation using existing hydraulic energy are possible by substituting the Soft Pressure Regulation System (SPRS) for a pressure reducing valves (PRV) in urban water distribution network (WDN) pipelines. The economical benefit and short start-up time are unique features of the SPRS that uses a pump as turbine (PAT). In this study, the numerical and experimental results of a single-stage centrifugal pump in direct and reverse working modes were compared and validated. The effect of passage width increasing, adding splitter blades and simultaneous modification of these parameters on improving the hydraulic performance of the PAT in the working range are investigated. Geometric modifications do not have the same effect on hydraulic parameters and efficiency in all operating ranges due to the significant range of flow rate variations in the WDN. Therefore, the statistical analysis was performed to identify the optimum modifications based on the PAT's working time in the specified flow rate ranges. The results show that simultaneous modification of parameters in the range of part-load condition (0.8QBEP) to over-load condition (1.2QBEP) reduces losses while increasing efficiency and power generation.

MnO2@MXene/Carbon Cloth as an Anode for Microbial Fuel Cells

AbstractHydrophobicity of carbon‐based anodes hinders bacterial adhesion and biofilm formation. Herein, MnO2@MXene coated carbon cloth (CC) was designed as an anode for microbial fuel cells (MFCs). The anode integrated the hydrophilicity and conductivity of MXene with the biocompatibility of MnO2. This unique structure promoted bacterial colonisation and biofilm formation on the anode surface. MnO2@MXene enhanced electricity generation performance and wastewater degradation efficiency owing to the synergistic effect of MXene and MnO2. The MFC achieved a short startup time and an effective extracellular electron transfer process. The MnO2@MXene/CC anode ensured a higher power density and efficient decolourisation in MFCs. The MFC device achieved a high maximum power density of 746.3 mW/m2 and a Congo red decolourisation efficiency of 87.6 % at 48 h. This work offers a potential strategy for the effective degradation of wastewater and recovery of electrical energy.

Experimental study of mechanical-capillary driven phase-change loop for heat dissipation of electronic devices and batteries

To solve the disadvantages of traditional phase-change heat dissipation technologies, such as instability in two-phase flow and difficulty in active temperature control, a mechanical-capillary driven hybrid phase-change loop (HPCL) is designed and tested. The experiment results show that the heating power and liquid-vapor pressure difference have a decisive influence on the transformation of heat transfer modes. With the increase of heating power while maintaining the liquid-vapor pressure difference unchanged, the baseplate of evaporator undergoes four heat transfer modes, i.e. flooded, partially flooded, thin film evaporation and overheating. Among them, thin film evaporation has the significant advantages of short start-up time and high heat transfer efficiency. Meanwhile, when the baseplate temperature is maintained below 85 ℃, the heat dissipation power is enhanced by about 6.5 times if the liquid-vapor pressure difference is increased from 0 kPa to 15 kPa. Therefore, increasing the liquid-vapor pressure difference is an active means in heat transfer enhancement. The heat transfer modes distribution diagram is drawn by taking into account of power and liquid-vapor pressure difference. Transition criterions between different heat transfer modes are given. The diagram suggests that the thin film evaporation region is in the shape of “horn”. In engineering application, liquid-vapor pressure difference can be regulated adaptively according to the actual operating characteristics of heat dissipation target to achieve the optimal heat dissipation effect. Furthermore, the accurate and rapid control over baseplate temperature can be realized by controlling liquid-vapor pressure difference. In such way, the accuracy of temperature control is within ±0.5 ℃. Therefore, controlling liquid-vapor pressure difference is a simple and effective means of active temperature control.

Design of new heat pump dryer system: A case study in drying characteristics of kelp knots

The heat pump dryer system (HPDS) attracts much attention for its high energy saving and excellent environmental performance. In this paper, a new set of double evaporator and normally closed loop HPDS (DENC-HPDS) with dehumidifying capacity of 3500 g/h and condensation temperature of 60 °C was designed. Drying experiments of kelp knots with DENC-HPDS under the conditions of drying temperature of 35, 40, 45 and 50 °C, wind speed of 0.5, 1.0, 1.5 and 2.0 m/s, loading density of 8.29, 12.29, 22.29 and 32.29 kg/m 3 , tray spacing of 50, 100, 150 and 200 mm were carried out, and the drying characteristics and mathematical drying models of the DENC-HPDS were investigated and analyzed. The designed DENC-HPDS solves the problem of heat and moisture imbalance and pollution of traditional HPDS effectively with short start-up time compared with traditional HPDS. The drying experiments shows that drying time generally decreases with the increase of drying temperature, wind speed and tray spacing. The optimal drying conditions are drying temperature of 45 °C, wind speed of 1.5 m/s, loading density of 22.29 kg/m 3 and tray spacing of 150 mm with the highest mean specific moisture extraction rate of 1.63kg/kWh. In ten drying models, the Verma et al. model has the best fitness to the experimental data and is more suitable to describe the heat pump drying process of kelp knots in this paper. Under the experimental conditions, the calculated effective moisture diffusion coefficients are in the range of 3.4687 × 10 −9 –11.3189 × 10 −9 m 2 /s and the average drying activation energy is 21.02 kJ/mol.

Thermal Management of a 48 V Lithium-Ion Battery Pack by Semiconductor Refrigeration

At present, 48 V mild hybrid battery systems are widely used in hybrid electric vehicles to reduce fuel consumption and emissions. The battery pack often operates at high discharge/charge rates and requires an efficient and compact battery thermal management system (BTMS) to control its temperature, improve its electrical performance and extend its life. Due to their short start-up times and simple structures, semiconductors can provide rapid refrigeration and cool a battery quickly in response to sudden high current rates. Therefore, semiconductors were applied to the BTMS of a 48 V battery. The performance of the semiconductor-based BTMS was studied by simulation and experiment at high discharge rates (up to 9.375 C). Firstly, a thermal model of the BTMS was developed that integrates a resistance-based battery thermal model, a semiconductor thermal model and a three-dimensional fluid-solid coupled heat transfer model. Unlike a traditional thermal model, the proposed model considers the joint influences of SOC, temperature and current on battery resistance and improves the predictive precision of the battery’s thermal behaviour. The thermal model was verified by an experiment, with the results showing that it could precisely describe the temperature increase in the battery (maximum average absolute error within 0.9°C). Finally, the BTMS thermal model was applied to predict the cooling performance of the semiconductor BTMS at an ambient temperature of 37°C and high current rates (up to 9.375 C), which was compared with that of an air-cooled BTMS. The results demonstrate that the semiconductor-based BTMS achieves lower battery temperature than the air-cooled BTMS and ensures a temperature difference within the 48 V pack of <1.6°C.

Carbon-based conductive materials enhance biomethane recovery from organic wastes: A review of the impacts on anaerobic treatment

Amongst the most important sustainable waste management strategies, anaerobic biotechnology has had a central role over the past century in the management of high-pollution load sources, such as food, agricultural and municipal wastes. During anaerobic digestion (AD), valuable by-products such as digestate and biogas are produced. Biogas (mainly composed of methane) is generated through a series of reactions between bacteria and archaea. Enhancement of AD process with higher methane yield, accelerated methane production rate, and shorter start-up time is possible via tapping into a novel methanogenic pathway discovered a decade ago. This fundamentally new concept that is a substitute to interspecies hydrogen transfer is called direct interspecies electron transfer (DIET). DIET, a thermodynamically more feasible way of electron transfer, has been proven to occur between bacteria and methanogens. It is well-documented that amendment of carbon-based conductive materials (CCMs) can stimulate DIET via serving as an electrical conduit between microorganisms. Therefore, different types of CCMs such as biochar and activated carbon have been amended to a variety of AD reactors and enhancement of process performance was reported. In this review, a comparative analysis is presented for enhancement of AD performance in relation to major CCM related factors; electrical conductivity, redox properties, particle size and dosage. Additionally, the impacts of AD operational conditions such as organic loading rate and temperature on CCM amended reactors were discussed. Further, the changes in microbial communities of CCM amended reactors were reviewed and future perspectives along with challenges for CCM application in AD have been provided.

Plasma steam methane reforming (PSMR) using a microwave torch for commercial-scale distributed hydrogen production

Although large-scale hydrogen production through conventional steam methane reforming (SMR) is available at an affordable cost, there is a shortage of hydrogen pipeline infrastructure between production plants and fueling stations in most places where hydrogen is needed. Due to the difficulties of transporting and storing hydrogen, onsite hydrogen production plants are desirable. Microwave plasma torch-based methods are among the most promising approaches to achieving this goal.The plasma steam methane reforming (PSMR) method discussed here has many benefits, including a high energy yield, a small carbon footprint, real-time fueling because of the short start-up time (<10 min), and the absence of expensive metal-based catalysts. Methane reforming and water gas shift reaction (WGSR) co-occur in the method advanced without a separate WGSR to achieve a high H2 yield.This study examines an experimental investigation of commercial-scale hydrogen production through PSMR utilizing a microwave torch system. The optimum results obtained showed that the hydrogen production rate was 2247 [g(H2)/h], and energy yield was 70 [g(H2)/kWh] of the absorbed microwave power. An assessment of the results indicated a similar trend to that of simulated data (ASPEN Plus). The experimental results presented in this paper demonstrate the potential of a catalyst-free PSMR for commercial-scale hydrogen production.

Three practical workflow schedulers for easy maximum parallelism

AbstractRuntime scheduling and workflow systems are an increasingly popular algorithmic component in HPC because they allow full system utilization with relaxed synchronization requirements. There are so many special‐purpose tools for task scheduling, one might wonder why more are needed. Use cases seen on the Summit supercomputer needed better integration with MPI and greater flexibility in job launch configurations. Preparation, execution, and analysis of computational chemistry simulations at the scale of tens of thousands of processors revealed three distinct workflow patterns. A separate job scheduler was implemented for each one using extremely simple and robust designs: file‐based, task‐list based, and bulk‐synchronous. Comparing to existing methods shows unique benefits of this work, including simplicity of design, suitability for HPC centers, short startup time, and well‐understood per‐task overhead. All three new tools have been shown to scale to full utilization of Summit, and have been made publicly available with tests and documentation. This work presents a complete characterization of the minimum effective task granularity for efficient scheduler usage scenarios. These schedulers have the same bottlenecks, and hence similar task granularities as those reported for existing tools following comparable paradigms.

Improvement of startup performance of the drag-type hydrokinetic rotor through two-stage configuration

The present study aims to reveal startup characteristics of a two-stage drag-type hydrokinetic rotor. Numerical simulation was performed to capture instantaneous flow characteristics and to develop a relationship between flow and rotor performance. The dependence of the rotational speed on hydraulic loads was modeled and solved using the six degree of freedom (SDOF) solver. The effect of the load coefficient on startup performance was investigated. A comparison between the two-stage rotor and a single-stage rotor was implemented. The results show that the two-stage rotor is superior to the single-stage rotor in terms of the startup performance. During the startup process, fluctuations of the angular velocity and the torque coefficient are mitigated with the introduction of the two-stage configuration. Relative to the single-stage rotor, the two-stage rotor starts up with high power coefficient but short startup time. At certain azimuthal position, the effect of the load coefficient on near-rotor flow patterns is insignificant. In the wake of the two-stage rotor, considerably different flow patterns are evidenced adjacent to the upper and the lower sub-rotors. The wake vortex structures are smooth but underdeveloped.

Improving Current Collection of Tubular Solid Oxide Fuel Cells

Solid Oxide Fuel Cells (SOFCs) are electrochemical devices with solid electrolyte materials that convert chemical energy in fuels into electrical energy. Tubular SOFCs (T-SOFCs) is one of the major SOFC configurations which has the advantages of good thermal conductivity, easy to seal and shorter start-up time. However, challenges remain in effectively collecting the current inside the tubular cells. Developing an efficient, easily applicable and cost-effective collector is imperative. The properties of a desired current collector are to: reflect the fuel cell performance, be able to withstand the fuel cell’s high working temperature environment, protect the fuel cell from damage, simplify the current collector application procedure, expand the contact surface between the tube and the current collector, and save cost.We have designed a current collector and identified the materials for inside tube current collection with desired characteristics such as high temperature tolerance, low electrical resistance, and low cost. The research focused on the effectiveness of the current collector and its durability at various fuel cell operation conditions. The design achieved a peak power density at 0.7V of 0.21W/cm2 at the temperature of 700oC for a conventional tubular SOFC with material set of Ni+8YSZ‖YSZ‖LSM. Comparing to the general metal (nickel, silver) current collectors, the studied material can reduce the cost from hundreds of dollars per yard to $0.13/yard. The paper will discuss the design and the cost-effective material selection of the current collector which provides a potential path for the commercialization of tubular SOFC technology.

Improving Current Collection of Tubular Solid Oxide Fuel Cells

Solid Oxide Fuel Cells (SOFCs) are electrochemical devices with solid electrolyte materials that convert chemical energy in fuels into electrical energy. Tubular SOFC is one of the major SOFC configurations which has the advantages of good thermal conductivity, easy to seal and shorter start-up time. However, challenges remain in effectively collecting the current inside the tubular cells. Developing an efficient, easily applicable, and cost-effective collector is imperative. The properties of a desired current collector are to: reflect the fuel cell performance, be able to withstand the fuel cell’s high working temperature environment, protect the fuel cell from damage, simplify the current collector application procedure, expand the contact surface between the tube and the current collector, and save cost. We have designed a current collector and identified the materials for inside tube current collection with desired characteristics such as high temperature tolerance, low electrical resistance, and low cost. The research focused on the effectiveness of the current collector and its durability at various fuel cell operation conditions. The design achieved a peak power density of 0.21 W/cm2 at 0.7V and 700oC for a conventional tubular SOFC with material set of Ni+8YSZ‖YSZ‖LSM. Comparing to the general metal (nickel, silver) current collectors, the material which is provided in the paper can reduce the cost from hundreds of dollars per yard to $0.13/yard. The paper will discuss the design and the cost-effective material selection of the current collector which provides a potential path for the commercialization of tubular SOFC technology.

Dynamic system modeling of thermally-integrated concentrated PV-electrolysis

Understanding the dynamic response of a solar fuel processing system utilizing concentrated solar radiation and made of a thermally-integrated photovoltaic (PV) and water electrolyzer (EC) is important for the design, development and implementation of this technology. A detailed dynamic non-linear process model is introduced for the fundamental system components (i.e. PV, EC, pump etc.) in order to investigate the coupled system behavior and performance synergy notably arising from the thermal integration. The nominal hydrogen production power is ∼2 kW at a hydrogen system efficiency of 16–21% considering a high performance triple junction III-V PV module and a proton exchange membrane EC. The device operating point relative to the maximum power point of the PV was shown to have a differing influence on the system performance when subject to temperature changes. The non-linear coupled behavior was characterised in response to step changes in water flowrate and solar irradiance and hysteresis of the current-voltage operating point was demonstrated. Whilst the system responds thermally to changes in operating conditions in the range of 0.5–2 min which leads to advantageously short start-up times, a number of control challenges are identified such as the impact of pump failure, electrical PV-EC disconnection, and the potentially damaging accentuated temperature rise at lower water flowrates. Finally, the simulation of co-generation of heat and hydrogen for various operating conditions demonstrates the significant potential for system efficiency enhancements and the required development of control strategies for demand matching is discussed.

A High-Efficiency Dual-Antenna RF Energy Harvesting System Using Full-Energy Extraction With Improved Input Power Response

This paper presents a dual-antenna energy harvesting (EH) system using full-energy extraction (FEE) to reduce the buffer capacitor requirement and improve the input power response speed. Instead of using large buffer capacitors (in the order of μF) at the rectifier output, the proposed FEE technique can efficiently harvest the incoming 915MHz radio-frequency (RF) energy using only a 1-nF capacitor per channel, while reducing the operating frequency of the subsequent DC-DC converter for power loss minimization. The two most popular RF rectifiers are investigated to relax the energy extraction degradation due to impedance mismatch. The boost DC-DC converter combines the harvested energy from the dual-inputs through the FEE controller. Fabricated in standard 0.18-μm CMOS and wire-bonded on an FR4 PCB, the dual-antenna EH system with the DC-DC converter operating typically at 6.25kHz demonstrates a measured peak system efficiency of 75.2% at an output power of 22.6 μW using only two 1-nF buffer capacitors at 1-μF load. With a significant buffer size reduction than prior art at similar efficiency/power level, a short startup time of ~45ms is achieved when the output rises from 0 to 1 V at 15.5 μW total rectifier output power, corresponding to 90% startup time reduction over the conventional approach.

Measurement of the gas flow stagnation temperature by the method of two identical thermocouples in the short-duration aerodynamic facilities

Investigations of the temperature and heat flux distributions over the external surface of flying vehicles are important for the development of hypersonic planes. For obtaining correct results, experiments are performed in short-duration high-enthalpy wind tunnels. Determination of the stagnation temperature of the flow in such facilities is a challenging task due to short start-up times and high flow temperature. In this paper a new method is proposed for determining the stagnation temperature of a gas flow in the short-duration aerodynamic wind tunnels with stepwise changes in its parameters. The method is based on using two identical thermocouples with different initial temperatures. It is shown that in the case of jump-like changes in flow parameters the instrument function of the difference of the thermocouple readings coincides with the instrument function of each thermocouple, and the instrument function itself is actually the normalized temperature difference. The instrument function obtained in the study allows temperature retrieval by the method of deconvolution. This approach is highly sensitive to random noise of experimental data; therefore, regularization methods are applied for high-frequency noise suppression. A procedure for choosing the regularization parameter for temperature reconstruction is proposed. The research novelty of the article is that the proposed method allows exact reproduction of the stepwise function and instrument function without any additional assumptions, while the measurements and dynamic calibration are performed in one experiment. Applicability of the method for obtaining the stagnation temperature in the short-duration high-enthrall wind tunnel IT-302 M ITAM SB RUS is demonstrated.

Coordinated operation of electricity and natural gas systems from day-ahead to real-time markets

Power systems worldwide are becoming more reliant on energy from natural gas, wind, and solar, posing potential reliability and coordination challenges from the tighter coupling of these infrastructure systems. This paper proposes a framework for the market-based coordination of electricity and natural gas system operations. The proposed framework includes a power system model that accounts for flexibility in the commitment of power plants with short start-up and shut-down times, coupled with a dynamic gas model that simulates when gas cannot be delivered to generators. The capabilities of the framework are illustrated using real-world electric power and gas systems, including scenarios around wind and solar penetrations and the analysis of time-variant, “shaped flow” gas nominations. Our results indicate that coordination between power and gas systems improves total gas delivery and reduces out-of-merit order dispatch in the electricity system, and that shaped flows may reduce unserved gas in systems with high penetrations of wind and solar energy sources. Coordination can have mixed effects on carbon-dioxide emissions, with emissions increasing with coordination for current systems during high load weeks but decreasing for systems with high renewable penetrations, particularly during periods of high variability.

Reduced graphene oxide@polydopamine decorated carbon cloth as an anode for a high-performance microbial fuel cell in Congo red/saline wastewater removal

A polydopamine decorated reduced oxide graphene (rGO@PDA) on carbon cloth (CC) as microbial fuel cell (MFC) anode was prepared by using dopamine polymerized reduction of oxide graphene. The anodes provided superhydrophilicity, high conductivity, good biocompatibility and long-term stability due to the combination of inorganic/organic components. These components and the resulting structure promoted enhancement of bacteria growth and enrichment, accelerated extracellular electron transfer between bacteria and anode surface, gained a high-performance rGO@PDA/CC MFC. The device achieved a short startup time of 18 h, maximum power density of 988.1 ± 5.2 mW·m−2 and Congo red decolorization efficiency of 89.7 ± 2.4% within 24 h. When Congo red and sodium acetate were continuously degraded, removal efficiency of chemical oxygen demand increased 77.8 ± 3.5% and 88.5 ± 5.8%, respectively. Thus, the synergistic effect of rGO and PDA effectively enhanced startup speed, power generation and pollutant degradation. The degradation products of Congo red were analyzed by mass spectrometry. Congo red was degraded to small organic molecules without azo bonds.

Smart catalyst deposition by 3D printing for Polymer Electrolyte Membrane Fuel Cell manufacturing

Polymer Electrolyte Membrane Fuel Cells (PEMFC) are arguably the most employed fuel-cell types in various industry sectors, as they operate at low temperature and exhibit short start-up time and high durability. PEMFC manufacturing is currently transitioning from low-volume to mass production. Within this effort, efficient catalyst deposition to produce MEA (Membrane Electrode Assembly) electrodes has become instrumental, since very expensive raw materials are involved. This work focuses on an Additive Manufacturing (AM) technique – a modified 3D printing approach – used to release catalytic inks onto PEMFC electrodes. Some catalyst-free suspensions were designed to resemble a catalytic ink and characterized to assess their printability by microextrusion. Mixtures of distilled water, ethanol and graphite were prepared and tested. Granulometric and rheometric analyses were conducted to optimize the composition towards low viscosity values and short drying time. Repeatability of the released amount and its homogeneousness onto the target surface were evaluated. The most suitable ink formulation was loaded with platinum, a perfluorosulfonic ionomer, a pore former (NH4CO3) and deposited onto Gas Diffusion Layers (GDL). Scanning Electron Microscopy (SEM) measurements were performed on the 3D-printed electrodes to characterize it. Preliminary electrochemical fuel-cell tests were carried out towards a comparison with conventional electrodes: the proposed deposition technique appears able to produce electrodes that align with state-of-the-art performance level.

Experimental investigation of the characteristics of thermosyphon with flat evaporator and micro-pillar arrays

This study experimentally investigated the cascaded start-up performance of thermosyphon with a flat evaporating surface combined with different sizes of micro-pillars. The thermosyphon was composed of a condenser section and an evaporator section. Different sizes of micro-pillar were processed on the surface of the evaporator bottom plate to enhance the heat transfer. A smooth flat surface was used as the standard reference for comparison with the micro-pillar surfaces. Deionized water was used as the working fluid to cool the condenser section of the thermosyphon. The operating pressure of thermosyphon was measured using a pressure sensor. Additionally, the evaporator section wall temperature and the temperature and flow rate of the cooling water were measured at nine different heat fluxes. The start-up performances of the thermosyphon with a smooth evaporator bottom plate (THSE) and thermosyphon with a micro-pillar in the evaporator bottom plate (THMPE) were compared. The THSE had a longer start-up time and a higher start-up temperature than the THMPE. When the heat flux was 68.6 W/cm2, the start-up time of the THMPE with a micro-pillar width of 0.2 mm and a height of 0.8 mm was reduced by 57.1% compared to THSE, and the start-up temperature was reduced by 28%. Thermosyphons with different micro-pillar widths showed various start-up performances for different heat fluxes. For a narrow micro-pillar width, THMPEs with larger micro-pillar heights had a lower start-up temperature and a shorter start-up time. As the micro-pillar width increased, the micro-pillar height had a different and more complex effect on the start-up performance of the thermosyphon. When the micro-pillar heights were 0.2 mm and 0.4 mm, the thermosyphon with wider micro-pillars had a longer start-up time with a lower heat flux but a shorter start-up time with a higher heat flux. When the micro-pillar heights were 0.6 mm and 0.8 mm, varying the micro-pillar width had a smaller influence on the start-up performance of the thermosyphon, but was dependent on the heat flux.