Thermal Performance Characteristics Research Articles

Thermal Performance Characterization of Battery Insulation on ATL1 Picosatellite Mission

Thermal Performance Characterization of Battery Insulation on ATL1 Picosatellite Mission

Experimental studies of thermal behavior, engine performance and emission characteristics of biodiesel / diesel / 1 pentanol blend in diesel engine

The present study investigates the significance of the utilization of biodiesel derived from waste cooking oil in diesel engines and its impact on engine output and environmental pollution after blending with diesel and 1-pentanol. The higher values of the ignition index and comprehensive performance index of 4.34 ×10−4mass/min°C2 and 13.71×10−6 mass2/min2 °C3, respectively, for D70B20P10 (70 % diesel, 20 % biodiesel & 10 % 1-pentanol by volume) indicate superior combustion performance. At full load, carbon monoxide and unburned hydrocarbon emissions from 1-pentanol blended fuels decrease significantly, ranging from 40 % to 52 % and 30.76–46.15 % compared to diesel. The D70B20P10 also showed an improved thermal efficiency of 28.68 % among all tested fuels at full load but slightly lower than diesel (29.56 %). Diesel demonstrated superior in-cylinder pressure (ICP) of 77 bar and heat release rate (HRR) of 41.1 J/ºCA owing to its excellent combustion characteristics. Introducing 5–10 % 1-pentanol in blend improved combustion, elevating ICP and HRR, attributed to enhanced fuel atomization and oxygen content. The sustainable process index value obtained for a global index per person is 0.002×10−4cap Litre-1, which lies between 0 and 1, indicates sustainability and compatibility of biodiesel production demonstration by universal biofuels (Andhra Pradesh).

Analysis of thermal performance characteristics of rotating packed beds using response surface methodology

Cooling towers play a crucial role in various industries to dissipate the heat of circulating water. This process involves the direct contact of atmospheric air and hot water from the condenser within a porous packed bed. The cooling towers suffers from their large size which results in escalating construction and maintenance expenses. In the present work, a rotating packed bed has been investigated experimentally for its evaporative heat transfer performance and is proposed as an alternative to cooling towers. In the chemical and processing sectors, rotating packed beds are being explored as a potential alternative to conventional distillation towers due to their process intensification capabilities. The principal reason behind this adaptation is the enhanced mass transfer rates achievable by rotating packed beds in a compact size. The aim of this study is to lay the foundation for rotating packed beds to achieve similar process intensification in various heat transfer applications. For this purpose, the parameters that describe the performance of a cooling tower such as air pressure drop, cooling range, heat rejection rate from water, cooling effectiveness, and Merkel number were selected to assess the performance of the rotating packed bed. The effect of various factors such as mass flow rate of air, mass flow rate of water, water inlet temperature, and rotational speed on the performance parameters was observed. Response surface methodology was used for the design of experiments, development of the regression equations, and optimization of the performance parameters of rotating packed bed. The cooling effectiveness value of up to 0.59 and the Merkel number of up to 1.88 were achieved in the rotating packed bed.

Bayesian inversion for in-situ thermal characterisation of walls in the presence of thermal anomalies

This paper develops a Bayesian inverse modelling framework for the in-situ characterisation of walls' thermal performance in the presence of thermal anomalies subject to uncertainty. For any given wall, the proposed framework uses in-situ contact measurements of temperature and heat flux in order to approximate the (posterior) distribution of a set of parameters which are inputs of a 3D heat transfer model of the wall that accounts for the presence of unknown anomalies. The set of inputs that we infer include (i) the geometry of the thermal anomaly as well was its material properties, (ii) the as-built thermophysical properties of the clear part (i.e. without anomaly) of the wall (iii) surface resistances and (iv) modelling errors that arise from unaccounted sources of uncertainty in the boundary conditions. The geometry of the unknown thermal anomaly is parameterised with a level-set function that is inferred within the proposed Bayesian approach. In order to incorporate prior statistical information of the thermal anomaly, a Gaussian process conditioned on measurements from thermal images is employed to build a prior on the level-set function. The posterior distribution of inferred inputs is approximated via the implementation of an Ensemble Kalman Inversion algorithm that provides stable and accurate approximations of the posterior. This paper also proposes a methodology that uses the inferred 3D model to derive a thermally equivalent 1D model of the wall that is suitable for its integration with existing building energy performance software. The proposed inverse modelling technique is experimentally validated by characterising the thermal performance of an insulation panel in the presence of a thermal anomaly. Our computations show that the proposed approach produces a 3D model that accurately describes thermal performance, and a derived equivalent 1D model that effectively reproduces the dynamic thermal performance of the insulation panel in the presence of the thermal anomaly.

Experimental investigation of effect of different configurations of semi-circular or half-round ribs on heat transfer enhancement in a rectangular duct

This research study investigated the impact of various configurations of semi-circular or half-round ribs on the thermal performance and frictional factor characteristics of a rectangular duct. During this research study, the ribs were provided on the inner surface of the test section’s bottom wall. Six distinct configurations of semi-circular ribs varying from continuous to hybrid arrangement were used. The range of Reynolds number was varied from 13,500 to 34,800; while the ratio of rib pitch to rib height (P/e ratio) was kept constant at 8. The ratio of the height of rib to hydraulic diameter of duct (also known as blockage ratio) was kept at 0.114. The results of experimental investigation showed that the Nusselt number ratio obtained was ranging from 1.36 to 2.74, while the friction factor ratio ranges from 1.70 to 4.51. The overall enhancement ratio for all configurations obtained was in the range of 1.06–1.80 times to that of plain duct. Among all rib configurations, the hybrid rib configuration showed superior ratio of Nusselt number and intermediate increase in ratio of friction factor as compared to all the other rib configurations. Hybrid rib configuration showed overall enhancement ratio values ranging from 1.45 to 1.80 times as compared to that of plain duct (duct without ribs) within the specified range of Reynolds number. The results of study showed that the hybrid configuration of semi-circular ribs exhibited superior overall thermal enhancement as compared to that of remaining tested rib configurations.

Experimental Investigation on Thermal Performance of Solar Air Heater using Nano-PCM

Herein, the performance of a solar air heater (SAH) is experimentally investigated, utilising an array of tubes as the absorbent part. The study evaluates the impact of incorporating Al2O3-paraffin wax as a non-PCM storage medium in comparison to a traditional flat-plate solar air heater, specifically under Najaf-Iraq climate conditions. The SAH is positioned at an inclination of 32.1 degrees with respect to the horizon, allowing it to align optimally with the solar direction. The results reveal notable differences in thermal performance characteristics among the various models. The highest thermal efficiency values are observed for distinct configurations: the proposed model achieves about 55.2%, the wax-supported model reaches 55.9%, and the nano-PCM-reinforced model attains 57.7%, while the traditional model lags at 48.2%. Furthermore, an analysis of different air mass flow rates highlights a crucial finding. Specifically, an air mass flow rate of 0.01 kg/s results in a higher temperature exiting from the system compared to a flow rate of 0.02 kg/s. This is attributed to the extended interaction time between the passing air and the absorbing surface, facilitating enhanced heat exchange. Consequently, the system's thermal efficiency experiences an increase. The study underscores the superior thermal performance and efficiency of the tube array nano-PCM collector type under Najaf city-Iraq climate conditions.

Ultra-Low Thermal Conductivity and Improved Thermoelectric Performance in Tungsten-Doped GeTe.

Compared to SnTe and PbTe base materials, the GeTe matrix exhibits a relatively high Seebeck coefficient and power factor but has garnered significant attention due to its poor thermal transport performance and environmental characteristics. As a typical p-type IV-VI group thermoelectric material, W-doped GeTe material can bring additional enhancement to thermoelectric performance. In this study, the introduction of W, Ge1-xWxTe (x = 0, 0.002, 0.005, 0.007, 0.01, 0.03) resulted in the presence of high-valence state atoms, providing additional charge carriers, thereby elevating the material's power factor to a maximum PFpeak of approximately 43 μW cm-1 K-2, while slightly optimizing the Seebeck coefficient of the solid solution. Moreover, W doping can induce defects and promote slight rhombohedral distortion in the crystal structure of GeTe, further reducing the lattice thermal conductivity κlat to as low as approximately 0.14 W m-1 K-1 (x = 0.002 at 673 K), optimizing it to approximately 85% compared to the GeTe matrix. This led to the formation of a p-type multicomponent composite thermoelectric material with ultra-low thermal conductivity. Ultimately, W doping achieves the comprehensive enhancement of the thermoelectric performance of GeTe base materials, with the peak ZT value of sample Ge0.995W0.005Te reaching approximately 0.99 at 673 K, and the average ZT optimized to 0.76 in the high-temperature range of 573-723 K, representing an increase of approximately 17% compared to pristine GeTe within the same temperature range.

Influence of Cassava Peels Biosolid Addition on the Technological Properties, Thermal Performance, and Microstructural Characteristics of Fired Clay Bricks

Influence of Cassava Peels Biosolid Addition on the Technological Properties, Thermal Performance, and Microstructural Characteristics of Fired Clay Bricks

Study of the thermal performance characteristics of shell and semi-circular tube heat exchanger using both baffles and nanofluid

Study of the thermal performance characteristics of shell and semi-circular tube heat exchanger using both baffles and nanofluid

Preliminary thermal performance characterization of a flexible separate heat pipe used for the tracking-type photovoltaic/thermal system

In the solar heating field, the separate heat pipe-based photovoltaic/thermal technology can improve the comprehensive utilization efficiency of solar energy and reduce the maintenance difficulty in long-term outdoor operation by preventing freezing and scaling problems. Its promotion and application are of great significance for reducing fossil energy consumption and carbon emissions, and thus have attracted much attention. However, the performance of conventional photovoltaic/thermal modules is limited by their frame shadow due to the insulation demand, which leaves plenty of room for overall efficiency gains. To solve this problem, a novel separate heat pipe-based photovoltaic/thermal system is proposed by introducing a dual-axis tracking method through a flexible separate heat pipe and side-altitude inclination. To preliminarily characterize the thermal performance of the flexible separate heat pipe in dual-axis tracking conditions, an indoor experimental platform of the flexible separate heat pipe using the solar collector and finned-tube heat exchanger in the water tank as the evaporator and condenser was set up. The effects of side inclination angle, altitude angle of the solar collector and solar irradiance on the thermal efficiency, mass flow rate, and thermal resistance of the system are investigated in detail. The experimental results show the system can generally maintain effective heat transfer in side inclination states, with thermal efficiency mostly ranging from 44.68% to 86.12%. The proposed flexible separate heat pipe is qualified for the dual-axis tracking of photovoltaic/thermal system and shows great potential in improving the utilization of solar energy.

Numerical investigation on the exhaust gas combustion of an SOFC in a catalytic multichannel burner

The utilization of the exhaust gas of a solid oxide fuel cell is important to improve the energy efficiency and control pollutant emission. In this work, the combustion of solid oxide fuel cell exhaust gas (H2/CO) in a honeycomb ceramic catalytic burner is investigated numerically. A 2D numerical combustion model with 17 channels is built to analyze the influence of channel position on thermal performance and combustion characteristics. The high burnout of H2 and CO is obtained as 96.75% and 97.75%, respectively. The channels can be divided into three groups from the inside to the outside as follows: part 1, from the 9th channel to the 13th channel; part 2, from the 14th channel to the 16th channel; and part 3, the 17th channel. The channels in the same group presented the same results of flow, temperature, and combustion. Compared with the other channels, the outermost channel shows notable differences in depressing the temperature of the whole channel, moving the maximum temperature downstream, enlarging the temperature bias of the lower and upper walls, and enlarging the combustion zone. H2 and CO perform different combustion processes in the honeycomb ceramic catalytic burner. Compared with H2, the initial position of CO conversion is more affected by channel distribution. In the 17th channel, the CO oxidation rate is controlled mostly by the slower oxygen adsorption and the resulting low O(s) coverage. In the 9th channel, the CO oxidation rate is controlled mostly by the wall temperature and fuel-limited. The burnout rate of H2 changes from 95% to 99.9% with the channel position, but the burnout of CO varies little. The closer the channel to the outer wall, the higher the proportion of heterogeneous reaction and the more the generated heat. The generated heat by the channel can present a diversity of 4%.

Numerical study on the heat transfer performance evaluation, flow characteristics, exergy efficiency, and entropy generation analysis of a novel coaxial geothermal heat exchanger

In order to improve the geothermal heating capacity of buildings, this paper proposes a coaxial geothermal heat exchanger (CGHE) with an inner tube assembled with continuous spiral fins (CSF). The thermal performance and flow characteristics of a CGHE with inner tubes assembled with different widths of CSF were numerically investigated at different rotational directions and rotational speeds (rpm = −30, −60, −90, −120, 30, 60, 90 and 120). The heat transfer mechanism in different rotational directions and rotational speeds was revealed and the heat transfer performance 、exergy efficiency and entropy generation were analyzed. The results of the study showed that the assembly of different width CSF on the inner tube of the CGHE exhibited completely different thermal performance and flow characteristics in the case of clockwise and counterclockwise rotation. Nu decreases in clockwise rotation and increases in counterclockwise rotation, but with small changes. The f of each H is always greater than the static f when rotating clockwise, and each width f increases as the clockwise rotation speed increases. And the f of each H in counterclockwise rotation is opposite to that in clockwise rotation. The PEC of each H decreases as the clockwise rotation speed increases and increases as the counterclockwise rotation speed increases, with a maximum PEC = 1.813 for H = 11 mm and rpm = 120. And counterclockwise rotation can improve the exergy efficiency of CGHE. The entropy generation rate is significantly higher than that of smooth tubes when Re exceeds 12,639.

Surface modification for improving interfacial, mechanical and thermal performance characteristics in epoxy composites: Electroless nickel enhancement of dendritic copper particle-reinforced epoxy

While studies on the incorporation of metal particles into the epoxy matrix are quite common, this research introduces a novel approach by incorporating electroless Ni-coated Cu particles with functional features into the epoxy matrix. Thus, it presents an innovative investigation of epoxy composites with enhanced both thermal and mechanical properties. Therefore, three samples of pure epoxy, dendritic Cu particle reinforced (20 wt%), and electroless Ni-coated dendritic Cu particle reinforced (20 wt%) epoxy composites were fabricated by mixing followed by casting into the mold. The epoxy and composite specimens underwent phase analysis through XRD, and morphological examinations were conducted using SEM equipped with an EDS analyzer, respectively. The hardness, tensile, and bending tests were conducted for mechanical characterization. To evaluate the thermal properties, DSC and TGA tests were employed to assess the impact of the Cu and the electroless Ni-coated Cu particles on the thermal stability of the composites. The mechanical analysis results showed that the pure epoxy sample had tensile and flexural strengths of 23.2 MPa and 43 MPa, respectively. These values increased significantly by 90 % and 311 % in the presence of Ni-coated dendritic Cu particles, reaching 54 MPa and 177 MPa, respectively. Thermal analysis results indicated that the Tg increased with the incorporation of dendritic Cu particles and Ni-coated dendritic Cu particles. Furthermore, the highest thermal conductivity was observed in the Cu-reinforced composites.

EXPERIMENTAL STUDIES ON Li-ION BATTERY PACK FOR TEMPERATURE DISTRIBUTION ANALYSIS DURING FAST DISCHARGING AND VARIOUS AMBIENT TEMPERATURE CONDITIONS

Lithium-ion batteries are the primary energy source for electric vehicles (EVs), which were developed to address environmental issues and the lack of energy resources. The temperature is a key factor in Li-ion batteries which affects their degradation and life span. In this study, the thermal performance characteristics of a 4S2P Li-ion battery pack are analyzed according to the change in the environmental temperatures of 25°C, 40°C, and 60°C and the discharge rates of 0.5C, 1C, 2C, and 3C of the battery. In the experiment, the maximum temperature rises in the battery pack at 0.5C discharge rate is within the optimum operation range with respect to all tested ambient temperature conditions. Meanwhile, it is higher at an ambient temperature of 25°C than at ambient temperatures of 40°C and 60°C during high-current discharge (1C, 2C, and 3C) operations. The results prove that the environmental temperature of 40°C provides better thermal performance than 25°C and 60°C operating levels. Also, the temperature distribution between neighboring cells in the pack increases as the C-rate increases from 0.5C to 3C, and this nonuniformity causing high heat generation can lead to a performance reduction of the module. This article primarily proposed a correlation between heat transfer and ambient temperatures in terms of discharge rate. The correlation is significant when designing thermal management systems for battery-powered devices.

Investigation of the thermal performance and heat transfer characteristics of the lithium-ion battery module based on an oil-immersed cooling structure

Based on the concept of direct contact liquid cooling, a compact oil-immersed battery thermal management system is designed in this work. In the experiment, methyl silicone oil, white oil, and transformer oil are used as coolants to study the cooling effect and the heat transfer characteristics of the system. It is found that three oils show good cooling effects and temperature uniformity in general at three discharge rates. The maximum average temperatures of the battery module immersed in silicon oil, white oil, and transformer oil reach 53 °C, 47.3 °C, and 45.6 °C, respectively, under the maximum discharge condition (2 C). It decreases by about 25 %, 33 %, and 35 % compared with the maximum temperature of the battery module under natural convection cooling (70.5 °C). In addition, the theoretical analysis verifies that the battery heat production and the ratio of heat absorbed by three oils to the total heat production increases with the discharge rate. At the end of 2 C discharge, the ratio of heat absorbed by silicone oil, white oil, and transformer oil to the total heat production reaches 38.9 %, 46.3 %, and 49.5 %, respectively. Theoretical calculations show that all three oils can effectively absorb the heat generated by the battery, and especially transformer oil can achieve an excellent cooling effect. The results further confirm the effectiveness of the oil-immersed battery thermal management system, which provides additional new insights for the future development of battery thermal management systems based on immersion cooling.

Experimental study on the quantitative evaluation of the thermal stability performance and heat insulation characteristics of fire‐fighting foam

AbstractFoam extinguishing agents are crucial for the suppression of flammable liquid fires. Their thermal stability performance and heat insulation characteristics are critical indicators to evaluate the efficiency of the fire‐fighting foam. There have been some studies focused on exploring the behavior of fire‐fighting foams exposed to radiant heating. However, the decay mechanisms and heat transfer behaviors of the foam at the micro‐scale are still unclear and require further clarification. Therefore, in this study, the volume reduction coefficient, falling time of foam column height, and the temperature profiles of the foam layer under the thermal radiation environment of different conditions are discussed. The results indicate that the high temperature generated by the radiative heat flux will accelerate the collapse rate of the foam layer. The stability of the foam structure will be seriously damaged. There is a relationship between heat radiation intensity and foam attenuation coefficient. The empirical model for reflecting the fire‐fighting foam collapse process under the fire environment with high heat radiation flux is modified. Moreover, the average collapse rate and temperature difference gradient are used to characterize the thermal stability performance and heat insulation characteristics of the foam. Analysis of the micro‐scale foam structure parameters from the foam scans has revealed that the thermal stability performance and heat insulation characteristics of the foam are stronger when the surface tension of the foam is within the range of 17.4–20.4 mN/m.

Synergetic effect of hydrogen supplementation with waste cooking oil biodiesel – An assessment of the emission, combustion and performance parameters of a compression ignition engine

This investigation aims at examine the effects of hydrogen gas at different flow rates in combination with biodiesel made from used cooking oil on the combustion, emissions, and performance parameters of an engine. In order to improve the thermal performance and combustion characteristics of the stationary engine and lower its emissions, hydrogen is injected through the main manifold at varying flow rates ranging from 3 to 9 LPM, and waste cooking oil biodiesel (WCO B20) is injected through the injector as the main fuel. Both of these fuels are used in conjunction with each other. Results of combustion characteristics revealed that the cylinder pressure enhanced by about 7.32 % using 9 LPM hydrogen flow through the main manifold compared to diesel fuel. Similarly, the HRR from the engine using 9 LPM hydrogen flow enhanced by about 9.43 and 13.76 % compared to diesel and WCO B20, respectively. A comparison is made between diesel fuel and with the proposed modified fuel on the engine's performance, which is assessed in terms of BTE and BSFC. For a range of different engine loads, several emission parameters including HC, NOx, CO, CO2, and smoke opacity are monitored and analyzed for the fuel that has been produced. The results showed that the BTE of the engine is higher in the case of WCO B20 with hydrogen fuel in the flow rate of 9 LPM by about 35.38 % at various engine loads in comparison with the other flow rates of hydrogen fuel, WCO B20 blend, and diesel fuel. Similarly, there is a significant decrease in the SFC by about 17.85 % of the fuel using hydrogen fuel at higher flow rates. The CO emissions with WCO B20 biodiesel blend and diesel fuel are higher, whereas there is a substantial reduction in the CO emission about 22.58 % using a higher concentration of hydrogen fuel along with the WCO B20 biodiesel blends. Similarly, the other emissions such as CO2, smoke and HC decrease about 5.38 %, 10.41 % and 5.38 % whereas the NOx formation increases about 7.67 % at peak loads due to a higher rate of combustion.

Thermal and aging performance characteristics of pouch-type lithium-ion battery using heat pipes under nonuniform heating conditions

Lithium-ion (Li-ion) batteries are excellent energy storage technologies for electric vehicles. However, the performance and life cycle of a battery can be degraded by extremely high temperatures under nonuniform heating conditions. This study aims to investigate the performance improvement of a battery thermal management system (BTMS) using heat pipes (HP) under various heat generation conditions. The cooling performances of the BTMS using aluminum plates (AP) and HP were compared by analyzing battery temperature and life cycle while varying the discharge rate (C-rate) from 1C to 5C and the ambient and liquid temperatures from 25 °C to 40 °C. Furthermore, the nonuniform heat ratio, defined as the heat ratio between the tab and bottom of the battery, was introduced to emulate the uneven temperature distribution, ranging from 1 to 3. The average temperature (Tavg) increases of AP and HP decreased by 22.7 % and 32 %, respectively, compared with that using natural convection (NC). HP showed a much lower maximum temperature (Tmax) and temperature difference (ΔT) of the battery than AP, owing to the effective heat transfer using the heat pipe. During cyclic operation, HP maintained stable Tmax and ΔT within 34.3 °C and 4 °C, respectively. As the nonuniform heat ratio increased, Tmax increased significantly, which was more severe in AP than in HP. HP exhibited up to a 41 % higher normalized performance index of Tmax than AP. Additionally, with the nonuniform heat ratio increasing from 1 to 3 at a C-rate of 5C, the ΔT of AP and HP increased by 7.6 °C and 4.4 °C, respectively. Finally, the normalized equivalent full cycles of AP and HP at a nonuniform heat ratio of 3 and a C-rate of 5C decreased by 4.3 % and 1.6 %, respectively, compared to their performance under uniform heat.

Investigation on unsteady thermal process of NEPE propellant based on an refined chemical kinetic model

This study presents a sophisticated investigation into the intricate heat and mass transfer mechanisms of NEPE composite propellant under realistic rocket motor conditions, with particular emphasis on the rapid depressurization effects. To accomplish this, we have developed an innovative particle packing algorithm coupled with a novel semi-global kinetics model. By integrating detailed chemical kinetics models for Ammonium perchlorate (AP) oxidizing powders, Cyclotetramethylene tetranitramine (HMX) oxidizing powders, and Nitroglycerin/1,2,4-Butane triol trinitrate (NG/BTTN) fuel-binder, we have constructed a meso-scale model of NEPE propellant based on comprehensive experimental data. Furthermore, a refined 9-step kinetic mechanism has been incorporated into the meso-scale model, along with a pressure drop model that accurately captures the intricate gas reaction domain. The predicted parameters of NEPE propellant have been meticulously compared with experimental results, demonstrating a remarkable level of agreement. Moreover, meticulous analyses have been carried out to investigate the complex thermal processes exhibited by this composite propellant under the challenging conditions of rapid depressurization combustion. These analyses primarily focus on unraveling the dynamic evolution of the gas-solid phase and the underlying thermal regression mechanism of the solid phase. Notably, our findings reveal intriguing temporal changes in local heat flux feedback spikes throughout the entire depressurization process, owing to the intricate topology structure of NEPE propellant, which comprises multiscale oxidizing micro-particles embedded within a fuel-binder matrix. This research significantly enhances our understanding of the thermal behavior and performance characteristics of NEPE composite propellant, thereby paving the way for future advancements in rocket propulsion technology.

Thermal performance improvement of a radial pulsating heat pipe with diverging channels by adopting Tesla valves at various heat fluxes

The thermal performance of a pulsating heat pipe (PHP) can be improved by increasing the flow circulation with the adoption of novel channel designs to minimize flow resistance. This study aimed to improve the thermal performance characteristics of a radial PHP with diverging channels by adopting Tesla valves. The effects of heat flux, condensation temperature, and heat transfer area ratio on the thermal resistance and heat transfer coefficient of the PHP with Tesla valves were measured under different heating and cooling conditions. In addition, the flow behaviors and pressure variations were analyzed for a short time frame. The PHP with Tesla valves exhibited a 17 %-lower thermal resistance than that without Tesla valves owing to the increased flow circulation with preferential movement in one direction. Furthermore, the heat transfer capability of the PHP with Tesla valves increased with increasing condensation temperature and heat transfer area ratio at the same heat flux. In addition, the optimal filling ratios were determined to be 70, 80, and 90 % for heat transfer area ratios of 0.13, 0.08, and 0.05, respectively. Finally, contour maps for the maximum temperature deviation were developed in terms of the heat flux, heat input, and heat transfer area ratio.