Yiding Cao

Florida International University | FIU · Department of Mechanical and Materials Engineering (MME)

This paper introduces the concept of onboard hot-water-storage-based power systems for green vehicles. The hot water at a moderately high temperature is stored onboard vehicles and its thermal energy is used to produce wheelwork through a heat engine to drive vehicles without combustion. The hot water’s wheelwork storage density matches or exceeds...

This paper describes an innovative renewable-energy approach aimed at minimizing fossil fuel reliance for power generation and heat supply. This strategy encompasses renewable energy storage, power production, and heat supply. By harnessing solar and other renewable energies, hot water is produced and preserved underground with minimal heat loss ov...

In industrial processes involving both heat and mass transfer, the enthalpy or total energy difference, not the temperature difference, is a more comprehensive driving-force potential for the design of heat exchanger systems, such as cooling towers. However, current enthalpy methods based on the Merkel integral require numerical integration with im...

In industrial processes involving both heat and mass transfer, the enthalpy or total energy difference, not the temperature difference, is a more comprehensive driving-force potential for the design of heat exchanger systems, such as cooling towers. However, current enthalpy methods based on the Merkel integral require numerical integration with im...

Direct-contact heat and mass transfer packing (or its alternative term, direct-contact heat and mass exchangers) are integral components in the cooling towers of thermal power plants and dryers. In cooling tower applications, such packings enable the efficient evaporation of water into an air stream using a counterflow configuration, thereby coolin...

This paper introduces utility-scale underground hot water storage (USUHWS) systems and evaluates their performance to enable renewable energy sources to produce dispatchable utility-scale power or supply heat with minimized interruption and impact by weather conditions. The USUHWS systems could retain the thermal energy content of the stored hot wa...

This paper introduces a novel air-water thermal power plant working at low temperatures and employing hot water as a heat-supply fluid to produce utility-scale power with high second-law efficiency. The air-water power plant uses both air and water as working fluids and employs a direct-contact mass and heat transfer packing to facilitate latent he...

The reciprocating-airfoil (RA) driven vertical take-off and landing (VTOL) aircraft is a new aircraft concept that utilizes the reciprocating motion of the wings to provide lift for take-off and landing. The RA wings are shaped like the wings of a fixed-wing airplane and work as fixed wings while cruising. The wing undergoes substantial linear moti...

The thermal management of electronics is essential, since their lifetime and reliability are highly dependent on their operating temperature and temperature uniformity. Regarding that, Reciprocating-Mechanism Driven Heat Loop (RMDHL) technology has been invented and shows potentiality to become an effective high heat flux cooling system. In this pa...

Structural analyses are commonly employed to test the integrity of aircraft component systems in the design stage to demonstrate the capability of the structural components to withstand what it was designed for, as well as to predict potential failure of the components. The analyses are also essential for weight minimization and selecting the most...

New modes of transportation systems are under intensive development because traditional systems fail to become mass transportation means due to their technological limitations. To meet the growing demand for VTOL vehicles, a novel VTOL technology, reciprocating-airfoil (RA) driven VTOL aircraft, had been introduced. The objective of this study is t...

In the design stage of an aircraft, structural analyses are commonly employed to test the integrity of the aircraft components to demonstrate the capability of the structural elements to withstand what they are designed for, as well as predict potential failure of the components. This research focused on the structural design and analysis of a high...

The significant increase in the heat dissipation associated with the increased throughput in computing, renewable energy, and electric vehicles has become a limitation to the evolution of these technologies. The needs for more effective thermal-management methods for higher heat fluxes and more uniform temperature have resulted in the development o...

Increasing the power density and heat dissipation in electronic equipment and their need for an efficient thermal management system have made the liquid cooling techniques inevitable in recent years. In most applications, liquid cooling systems work in conjunction with more traditional cooling methods, such as conduction and convection heat transfe...

reciprocating flow of the working fluid inside a heat transfer device while maintaining substantial temperature uniformity over its evaporator section. The objective of this paper is to numerically simulate a bellows-type RMDHL to predict its operational performance under different working conditions as well as a conventional dynamic pump-driven he...

A literature review related to miniature and micro heat pipes is given. It is found that longitudinal groove designs are crucial to increase the heat transport capacity of miniature heat pipes. In addition to the operational limitations of conventional heat pipes, micro heat pipes may be subject to the vapor continuum limitation, which may prevent...

Heat pipe technology offers a possible cooling technique for structures exposed to high heat fluxes, as in turbomachinery such as compressors and turbines. However, in its current configuration as single heat pipes, implementation of the technology is limited due to the difficulties in manufacturability and costs. Hence, a study to develop a new ra...

A bellows-type Reciprocating-Mechanism Driven Heat Loops (RMDHL) is a novel heat transfer device that could attain a high heat transfer rate through a reciprocating flow of the working fluid inside the heat transfer device. Although the device has been tested and validated experimentally, analytical or numerical study has not been undertaken to und...

A bellows-type Reciprocating-Mechanism Driven Heat Loops (RMDHL) is a novel heat transfer device that could attain a high heat transfer rate through a reciprocating flow of the working fluid inside the heat transfer device. Although the device has been tested and validated experimentally, analytical or numerical study have not been undertaken to un...

An effective design option for a cooling system is to use a two-phase pumped cooling loop to simultaneously satisfy the temperature uniformity and high heat flux requirements. A reciprocating-mechanism driven heat loop (RMDHL) is a novel heat transfer device that could attain a high heat transfer rate through a reciprocating flow of the twophase wo...

A systematic thermodynamic analysis is presented for a recompression S-CO2 Brayton cycle incorporating a flow split between the main and recompressing compressors, a high-Temperature recuperator (HTR), and a low-Temperature recuperator (LTR). It is found that the efficiency of the Brayton cycle can reach 44.9% with a moderate reactor core outlet te...

In this study, the performance of a SBC (supercritical gas Brayton cycle) using CO2-based binary mixtures as the working fluids have been studied. Based on the thermodynamic analyses, an in-house code has been developed to determine the cycle efficiency and the amounts of heat transfer in the HTR (high temperature recuperator) and the LTR (low temp...

The most significant hindrances to the technological advances in high power electronics (HPE) and digital computational devices (DCD) has always been the issue of effective thermal management. Energy losses during operation cause heat to build up in these components, resulting in temperature rise. Finding effective thermal solutions will become a m...

This paper introduces separate-type heat pipe (STHP) based solar receiver systems that enable more efficient operation of concentrated solar power plants without relying on a heat transfer fluid. The solar receiver system may consist of a number of STHP modules that receive concentrated solar flux from a solar collector system, spread the high conc...

Heat losses to the environment may significantly affect engine performance. To accurately account for the heat-loss effect, engine performance simulation should be carried out based on a complete model which includes all four strokes of an engine cycle. In this paper, a mathematical model that includes the intake stroke, compression stroke, combust...

In order to take full advantage of the heat from high temperature gas cooled reactor, thermodynamic analysis of high-temperature helium heated methane, ethanol and methanol steam reforming for hydrogen production based on the Gibbs principle of minimum free energy has been carried out using the software of Aspen Plus. Effects of the reaction temper...

The objectives of this paper are to introduce a new heat engine and evaluate its performance. The new heat engine uses a gas, such as air, nitrogen, or argon, as the working fluid and extracts thermal energy from a heat source as the energy input. The new heat engine may find extensive applications in renewable energy industries, such as concentrat...

In this study, three copper water rotating heat pipes having inner diameters of 1.5, 2, and 3 mm, respectively, are fabricated and tested. The effectiveness of the copper water heat pipe is first validated by comparing its performance with that of a copper cylinder having the same outer diameter. The heat pipes are then tested to prove their reliab...

This paper introduces separate-type heat pipe (STHP) based solar receiver systems that enable more efficient operation of concentrated solar power plants without relying on a heat transfer fluid. The solar receiver system may consist of a number of STHP modules that receive concentrated solar flux from a solar collector system, spread the high conc...

The reciprocating-mechanism driven heat loop (RMDHL) is a novel two-phase heat transfer device that could find many important applications in energy systems and electronic cooling. However, the previous RMDHL is based on a solenoid driver that may have difficulty in handling a large amount of heat transfer rate over a long distance due to the drive...

A radially rotating high-temperature heat pipe is an effective heat transfer device that employs the centrifugal force to return the condensate in the condenser section to the evaporator section of the heat pipe. Combining the traditional air cooling technique with the rotating heat pipe for gas turbine blade cooling represents a new cooling method...

This paper introduces a new heat engine using a gas, such as air or nitrogen, as the working fluid that extracts thermal energy from a heat source as the energy input. The heat engine is to mimic the performance of an air-standard Otto cycle. This is achieved by drastically increasing the time duration of heat acquisition from the heat source in co...

An internal-combustion engine platform, which may operate on a portfolio of cycles for an increased expansion ratio, combustion under constant volume, variable compression ratio, and cold start, is introduced. Through unique thermodynamic cycles, the engine may be able to operate on a much greater expansion ratio than the compression ratio for a si...

The pulsating/oscillating heat pipe (PHP/OHP) is a relatively new, efficient, two-phase heat-Transfer device, which has attracted considerable interest due to its unique features in comparison with other types of heat pipes. In this paper, the most recent experimental and theoretical research work on the PHP and its derivatives is discussed and sum...

A new cold-start approach for internal combustion engines is described, which may be particularly suitable for an engine using an alternative fuel, such as ethanol or methanol. One of the cylinders in the engine may be equipped with a holding chamber in the cylinder head for the cold-start purpose. The holding chamber may be opened or closed by a h...

This paper describes an emerging cooling technique of the miniature high-temperature rotating heat pipe (MHTRHP) and its applications in gas turbine engines. The working principle of the MHTRHP and its disposition in the turbine blade and disk are first elaborated, followed by experimental and numerical studies of the subject. The study in the past...

The convection heat loss from cavity receiver in parabolic dish solar thermal power system can significantly reduce the efficiency and consequently the cost effectiveness of the system. It is important to assess this heat loss and subsequently improve the thermal performance of the receiver. This paper aims to present a comprehensive review and sys...

Three working-liquid charging methods for miniature heat pipes are introduced, and their advantages and disadvantages are described. The methods are referred to as the micro-syringe method, thermodynamic equilibrium method, and capillary-tubing method. Using these methods, two types of ceramic heat pipes were charged and tested. The ceramic heat pi...

This paper proposes a parabolic dish/AMTEC solar thermal power system and evaluates its overall thermal–electric conversion performance. The system is a combined system in which a parabolic dish solar collector is cascaded with an alkali metal thermal to electric converter (AMTEC) through a coupling heat exchanger. A separate type heat-pipe receive...

The alkali metal thermal to electric converter (AMTEC) is one of the most promising technologies for direct conversion of thermal energy to electricity and has been receiving attention in the field of energy conversion and utilization in the past several decades. This paper aims to present a comprehensive review of the state of the art in the resea...

With a substantially increased gas inlet temperature in modern gas turbine engines, the cooling of turbine disks is becoming a challenging task. In order to reduce the temperature at the disk rim, a new turbine disk incorporating radially rotating heat pipes has been proposed. The objective of this paper is to conduct a numerical investigation for...

This paper conducts experimental and analytical studies of a novel heat-transfer device, reciprocating-mechanism driven heat loop (RMDHL) that facilitates two-phase heat transfer while eliminating the so-called cavitation problem commonly encountered by a conventional pump. A RMDHL normally includes a hollow loop having an interior flow passage, an...

A liquid cooler module (LCM) employing a high thermal-conductivity, pitch-based carbon foam is studied. The newly developed carbon foam has an effective conductivity up to 150 W/m-K and porosity up to 90%. It is believed that this high-conductivity carbon foam could significantly enhance the heat transfer due to the thermal dispersion effect. To pr...

In this study, three copper-water rotating heat pipes having inner diameters of 1.5, 2, and 3 mm, respectively, are fabricated and tested. The effectiveness of the copper-water heat pipe is first validated by comparing its performance with that of a copper bar having the same inner and outer diameters. The heat pipes are then tested to prove their...

This technical note describes the spontaneous liquid uplift in biliquid capillary siphons. It was found that, in general, liquids that have a low surface tension to wet the wick material and a low viscosity (methanol, etc.) could be spontaneously uplifted to liquids with a high surface tension (water, etc.) or high viscosity (glycerin, etc.) throug...

This paper introduces a bio-inspired fuel cell stack that has a substantially increased specific reactive surface area. The fuel cell stack is based on micro fuel-cell units that generally has a circular shape and an effective diameter on the order of 1 mm. A number of fuel cell units are arranged to form a fuel cell module, and then these modules...

The capillary siphon is a device capable of transporting a liquid from a higher level to a lower level by capillary action under gravity. The device is usually configured in an inverted U-shape with an intake end and a discharge end. However, to the authors’ knowledge, the prior arts have not disclosed a process or apparatus that utilizes the capil...

A comprehensive analysis on a novel energy recovery system for reformate-based proton exchange membrane (PEM) fuel cell systems is presented. The energy recovery system includes a throttling valve, a heat exchanger, a compressor, and is coupled with a coolant loop for the fuel cell stack. The feed stock of the fuel reformer, which is primarily a mi...

A passive device is utilized for transferring methanol into water through a wick material. The wick material preferentially has a higher wicking capability with respect to methanol than water, and operates in a siphon fashion with the intake end in contact with methanol and the discharge end in contact with water. Due to the difference of wicking c...

To achieve a high heat-flux level and reduce manufacturing costs associated with conventional heat pipes, the concept of network heat spreaders employing a boiling heat-transfer mechanism in a narrow space had been proposed, and several flat-plate wickless heat spreaders had been designed and fabricated. The heat spreaders had been tested under dif...

This paper introduces a novel heat transfer mechanism that facilitates two-phase heat transfer while eliminating the so-called cavitation problem commonly encountered by a conventional pump. The heat transfer device is coined as the reciprocating-mechanism driven heat loop (RMDHL), which includes a hollow loop having an interior flow passage, an am...

Material temperature limitations impose an upper limit on the amount of work able to be extracted from a turbine. Cooling technologies allow turbine material to remain below upper temperature limitations while allowing for hotter combustor exit temperatures. Increased cooling effectiveness can also decrease cost by decreasing material temperature r...

This paper describes an energy recovery system that recovers waste thermal energy from a fuel cell stack and uses it for fuel reforming purposes. The energy recovery system includes a throttling valve, a heat exchanger, and a compressor, and is coupled with a coolant loop of the fuel cell stack. The feed stock of a fuel reformer, which is primarily...

The concept of the network heat pipe employing the boiling heat-transfer mechanism in a narrow space is described. Two flat-plate wickless network heat-pipes (or thermal spreaders) are designed, fabricated, and tested based on this concept. The fabricated thermal spreaders, which are made of copper or aluminum, are wickless, cross-grooved heat tran...

A radially rotating miniature high-temperature heat pipe employs centrifugal force to return the condensate in the condenser section to the evaporator section. The heat pipe has a simple structure, very high effective thermal conductance and heat transfer capacity, and can work in hostile high-temperature environments. In this research, a high-spee...

An isothermal journal bearing has been developed by incorporating heat-pipe-cooling technology. The research work reported in this paper is an experimental investigation that was conducted to study the thermal-tribological performance of the isothermal journal bearing subject to frictional heating. A stainless-steel journal bearing that incorporate...

Three working-liquid charging methods for miniature heat pipes are introduced, and their advantages and disadvantages are described. Using these methods, two types of ceramic heat pipes were charged and tested. The ceramic heat pipes were made of alumina and have overall dimensions of 89 mm × 12 mm × 2.9 mm and a designed vapor space of 82.5 mm × 4...

Radially rotating heat pipes have been proposed for cooling gas turbine disks working at high temperatures. A disk incorporating the heat pipe would have an enhanced thermal dissipation capacity and a much lower temperature at the disk rim and dovetail surface. In this paper, extensive numerical simulations have been made for heat-pipe-cooled disks...

The radially rotating miniature high-temperature heat pipe is a wickless heat pipe, which has a simple structure and low manufacturing cost, and can withstand strong vibrations in a high-temperature environment. In this paper, the radially rotating miniature high-temperature heat pipe having a diameter in the range of 1.5–2 mm is analyzed by employ...

Radially rotating miniature heat pipes for turbine blade cooling are studied by employing appropriate flow and heat transfer modeling as well as experimental tests. Extensive experimental tests on the heat pipes with different influential parameters are undertaken under a constructed high-speed rotating apparatus, and various effects of these param...

Designing pistons with effective cooling is crucial to preventing piston failure and improving engine service life. A piston design that incorporates the heat-pipe cooling technology may provide a new approach that could improve the thermal-tribological performance of heavy-duty diesel engine pistons. A simplified piston crown with an annular recip...

Optimization of flat miniature heat pipes was carried out based on the existing and newly obtained experimental results and the quasi-Newton algorithms employing the BFGS (Broyden, Flether, Golfarb, Shanno) method. The heat pipe contains capillary axial grooves that were cut using the method of electric-discharge-machining (EDM). The general multiv...

Radially rotating heat pipes have been proposed for cooling gas turbine disks working at high temperatures. A disk incorporating the heat pipe would have an enhanced thermal dissipation capacity and a much lower temperature at the disk rim and dovetail surface. In this paper, extensive numerical simulations have been made for heat-pipe-cooled disks...

An isothermal journal bearing that incorporates heat-pipe cooling technology has been developed. The heat pipe can spread frictional heat rapidly along the bearing circumference, resulting in a uniform temperature distribution in the bearing with a low peak temperature and stable transient thermal performance. A numerical model has been developed f...

This paper reports the development of an isothermal journal bearing by employing heat-pipe cooling technology for improved thermal-tribological performance. A stainless-steel bearing with a number of heat-pipe grooves which use methanol as the working fluid was designed and constructed to verify the heat-transfer mechanism in the isothermal journal...

A set of closed-form solutions for the liquid film distributions in the condenser section of a radially rotating miniature heat pipe and for the vapor temperature drop along the heat pipe length are derived. The heat transfer limitations of the heat pipe are analyzed under turbine blade cooling conditions. Analytical results indicate that the conde...

The surface temperature of contact elements is one of the most important factors that influences the performance and life of tribological systems. Heat-pipe cooling seems to be a promising means for enhanced heat transfer. The heat input at the surface and the heat pipe as a heat sink represent a system of heat source/heat sink (HSHS). In this pape...

In modern aero-engines, a turbine disk is normally cooled by compressed air bled from the engine compressor. A literature survey regarding the turbine disk cooling reveals that although the average air-cooling heat transfer coefficient is generally high, the local heat-transfer coefficient at the disk rim is low. Impinging jet cooling could be used...

Piston design that incorporates the heat pipe cooling technology may provide a new approach for piston-temperature control. A simulated piston crown that contains an annular reciprocating heat pipe is developed to investigate the effect of heat pipe cooling on the piston crown temperature distribution. For this purpose, a reciprocating engine testi...

The first part of this series of papers reports the development of a simulated piston crown with an annular reciprocating heat pipe and the investigation on the effect of heat-pipe cooling on the piston-crown temperature distribution. This paper presents the modeling of the simulated piston crown with the finite-element method and the analysis of i...

The reciprocating heat-transfer device or reciprocating heat pipe has a high effective thermal conductance, and applications can be found in various reciprocating mechanisms, including offset cam mechanisms, Scotch yoke mechanisms, and piston assemblies of internal combustion engines. The liquid return mechanism presents the most important operatin...

Bearing vibrations in turbogenerators are common failure modes. Identification of vibration failure during the operation of turbogenerators and the subsequent quick failure elimination in a short shut down period are very important to turbine engineers. In this paper, a brief theoretical analysis of the characteristics of the frequency spectrum and...

Heat transfer limitations of radially rotating heat pipes for turbomachinery applications are evaluated analytically. It was found that the condenser limitation normally encountered in low-temperatu re rotating heat pipes no longer exists for the high-temperature heat pipes studied in this paper. When the rotating speed is very high, however, the v...

The concept of the network heat pipe employing the boiling heat-transfer mechanism in a narrow space is described. Two flat-plate wickless network heat-pipes (or thermal spreaders) are designed, fabricated, and tested based on this concept. The fabricated thermal spreaders, which are made of copper and aluminum, are wickless, cross-grooved heat-tra...

Working fluid filling is one of the most difficult problems normally encountered in micro/miniature heat pipe manufacturing and processing. Three methods for proper heat pipe filling are introduced and evaluated in this paper. These methods are referred to as the screw-piston valve/vacuum bypass, screw-piston valve/sealed reservoir, and micro-syrin...